RE: [Flightgear-devel] Spitfire Hurricane manuals
On 4/19/04 at 11:12 PM Vivian Meazza wrote: All you ever wanted to know about a Merlin with 2 speed, 2 stage supercharging is here: http://www.unlimitedexcitement.com/Pride%20of%20Pay%20n%20Pak/Rolls-Royce%2 0 Merlin%20V-1650%20Engine.htm Except exactly how the boost contol valve worked :-) Nice link! I've found a reference describing the BCV mechanism (Thrust for Flight by W. Thomson), apparently it consisted of a stack of metal aneroids that contract under increased pressure. This makes perfect sense - it would measure absolute pressure, and I believe is similar to the mechanism used in many barometers. Cheers - Dave This message has been scanned but we cannot guarantee that it and any attachments are free from viruses or other damaging content: you are advised to perform your own checks. Email communications with the University of Nottingham may be monitored as permitted by UK legislation. ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Spitfire Hurricane manuals
On Wed, 28 Apr 2004 12:26:42 +0100, David wrote in message [EMAIL PROTECTED]: On 4/19/04 at 11:12 PM Vivian Meazza wrote: All you ever wanted to know about a Merlin with 2 speed, 2 stage supercharging is here: http://www.unlimitedexcitement.com/Pride%20of%20Pay%20n%20Pak/Rolls- Royce%2 0 Merlin%20V-1650%20Engine.htm Except exactly how the boost contol valve worked :-) Nice link! I've found a reference describing the BCV mechanism (Thrust for Flight by W. Thomson), apparently it consisted of a stack of metal aneroids that contract under increased pressure. This makes perfect sense - it would measure absolute pressure, and I believe is similar to the mechanism used in many barometers. ..search these for aneroid. http://naca.larc.nasa.gov/index.cgi?method=searchlimit=25offset=0mode=simpleorder=DESCkeywords=supercharger+stage http://www.cebudanderson.com/viewfromtheline.htm http://www.dallasjournal.com/articlesview.php?ID=295 http://www.aircadets.org/pdf/acp33vol3.pdf http://www.unlimitedexcitement.com/Griffon Budweiser/Rolls-Royce Griffon Engine.htm http://www.home.aone.net.au/shack_one/rolls.htm -- ..med vennlig hilsen = with Kind Regards from Arnt... ;-) ...with a number of polar bear hunters in his ancestry... Scenarios always come in sets of three: best case, worst case, and just in case. ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
RE: [Flightgear-devel] Spitfire Hurricane manuals
Andy wrote Vivian Meazza wrote: However, eng-power should be the un-supercharged max power, so I reduced eng-power value, No no, I was wrong. Use the superchared value, the eng-power gets corrected before solving to assume max sea level manifold density (i.e. with boost and wastegate applied). Is it possible that reduction gearing reduces engine revs for a given propeller rpm? I thought it was the other way around. You are correct. The gear-ratio value is multiplied by the engine RPM to get the propeller RPM. Typical PSRUs will have a value less than 1.0. Andy OK, I'll try again, this time with the supercharged power figures. Thank goodness - they are the only good power values available! Vivian ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
RE: [Flightgear-devel] Spitfire Hurricane manuals
Andy Ross Vivian Meazza wrote: However, eng-power should be the un-supercharged max power, so I reduced eng-power value, No no, I was wrong. Use the superchared value, the eng-power gets corrected before solving to assume max sea level manifold density (i.e. with boost and wastegate applied). Is it possible that reduction gearing reduces engine revs for a given propeller rpm? I thought it was the other way around. You are correct. The gear-ratio value is multiplied by the engine RPM to get the propeller RPM. Typical PSRUs will have a value less than 1.0. Andy This converges (1): eng-power=1140 eng-rpm=2850 turbo-mul=2 wastegate-mp=48 cruise-alt=17500 cruise-power=1140 cruise-speed=308 cruise-rpm=5975 takeoff-power=900 takeoff-rpm=5000 manual-pitch=true gear-ratio = 0.477 As does this (2): eng-power=1140 eng-rpm=2850 turbo-mul=2 wastegate-mp=48 cruise-alt=17500 cruise-power=1140 cruise-speed=308 cruise-rpm=2850 takeoff-power=900 takeoff-rpm=2000 manual-pitch=true gear-ratio = 0.477 This does not (3): eng-power=1140 eng-rpm=2850 turbo-mul=2 wastegate-mp=48 cruise-alt=17500 cruise-power=1140 cruise-speed=308 cruise-rpm=1360 takeoff-power=900 takeoff-rpm=1200 manual-pitch=true gear-ratio = 0.477 I ran FGFS using (2). From the property browser, at throttle = 1 engine rpm = 6779. I note that 6779 * 0.477 = 3233.6 This also converges nicely (4): eng-power=1140 eng-rpm=2850 turbo-mul=2 wastegate-mp=48 cruise-alt=17500 cruise-power=1140 cruise-speed=308 cruise-rpm=2850 takeoff-power=900 takeoff-rpm=2650 manual-pitch=true gear-ratio = 1 I now ran FGFS using (4). At throttle = 1 from property browser engine rpm = 3233.8 I conclude from the foregoing that the gear ratio is being applied incorrectly by YASim. I think that the correct input data is at (3) above. Sign wrong somewhere? Vivian ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Spitfire Hurricane manuals
Vivia Meazza wrote: As does this (2): cruise-speed=308 cruise-rpm=2850 This does not (3): cruise-speed=308 cruise-rpm=1360 Again, these are *wildly* different propoellers you are specifying. The second one is going to end up with four (!) times the force coefficient. In general, multiplying any number in the configuration file by a factor of two and expecting the aircraft to perform similarly just isn't going to work. Is there another typo? What are you trying to accomplish? Andy ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Spitfire Hurricane manuals
Vivian, Are you aware of this data I once sent to the list: http://baron.flightgear.org/pipermail/flightgear-flightmodel/2003-March/002130.html Erik ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
RE: [Flightgear-devel] Spitfire Hurricane manuals
Andy Ross tried again! Vivian Meazza wrote: As does this (2): cruise-speed=308 cruise-rpm=2850 This does not (3): cruise-speed=308 cruise-rpm=1360 Again, these are *wildly* different propoellers you are specifying. The second one is going to end up with four (!) times the force coefficient. In general, multiplying any number in the configuration file by a factor of two and expecting the aircraft to perform similarly just isn't going to work. Is there another typo? What are you trying to accomplish? Andy The engine I'm trying to specify developed 1140 HP at engine revolutions of 2850 rpm at a boost pressure of 9 psi. It was fitted with 1:0.477 reduction gearing, which I think means that the propeller turned at 1360 rpm. Thus, if I have understood all of the various emails correctly, leads to a specification file: eng-power=1140engine power output = 1140 HP eng-rpm=2850 @ 2850 rpm (supercharged) turbo-mul=2 Turbo multiplication factor = 2 wastegate-mp=48 Boost Control Valve = 48 in Hg absolute cruise-alt=17500 Cruise altitude = 17500 ft cruise-speed=308 cruise speed at cruise altitude = 308 kts cruise-power=1140 Power absorbed by propeller at cruise = 1140 HP cruise-rpm=1360 Propeller cruise rpm 2850 * 0.477 = 1360 rpm takeoff-power=900 take off numbers takeoff-rpm=1200 manual-pitch=true gear-ratio = 0.477reduction gear of 1:0.477 I'm reasonably confident that the numbers are in accordance with the published data for the engine. This results in a YASIM output; Iterations: 1 Drag Coefficient: 1000.00 Lift Ratio: 1.00 Cruise AoA: 0.00 Tail Incidence: -0.0 Approach Elevator: 0.00 CG: -2.528, 0.000, -0.270 FGFS locks up attempting to run with these settings, not unexpectedly. I made an alternative assumption as an experiment: that cruise-rpm was the engine rpm at cruise - 2850. They are also about the lowest values for which YASim converges. With these settings, YASim converges with these results: Iterations: 2320 Drag Coefficient: 6.279826 Lift Ratio: 360.380524 Cruise AoA: 0.770977 Tail Incidence: -0.8144328 Approach Elevator: 0.939014 CG: -2.523, 0.000, -0.276 FGFS runs with this input, but when throttle = 1 engine rpm = 6928, which is as expected for a propeller rpm of 2850 and a gear ratio of 0.477. I had hoped to see the engine rpm stay constant, and the propeller rpm to drop, but, as I say, I was just experimenting. Apart from the engine rpm the model performs well with these settings. I think we have to assume that either the published engine parameters are outside YASim's calculations in some way, or that I still have some fundamental misunderstanding of what goes where in the file. Sorry to be a nuisance with all these queries, and thank you for your patience and help. Regards Vivian ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
RE: [Flightgear-devel] Spitfire Hurricane manuals
Andy Ross wrote Vivian Meazza wrote: With these values eng-power=1140 eng-rpm=2850 cruise-power=2850 cruise-rpm=1359 takeoff-power=1100 takeoff-rpm=1359 YASim appears go into a loop and provides no output. These settings don't make much sense in combination. The eng setting is a maximum power (at standard sea level) for the engine without supercharging. In this case, the normally aspirated engine develops 1140 HP at max RPM. The cruise numbers are used to fix the propeller's maximum efficiency peak. The propeller you are using wants to sink 2850 HP (more than double max sea level power) at less than half (!) of the engine's max RPM. Even with 4x supercharging (which sounds kinda high to me, but I'm not an expert), that's just not going to work. Are you working from POH numbers for this engine that might be typoed or misinterpreted? The takeoff values correspond to the power and RPM developed by the aircraft at max throttle and zero airspeed. It's there because propellers have funny, non-linear behavior in the very low pitch regime (when the blades are partially stalled). The default model produces strange results here, so the FDM allows you specify a clamp to match real-world behavior. It's not important to the solver, or for in-flight performance. I'll look into the apparent infinite loop behavior. Andy The numbers are correct, it's how I've interpreted them and where I've put them that is the problem :-) The eng setting: the documentation that I am using (readme YASim) indicates that it is the brake horsepower at cruise I presumed that this was A. The supercharged output. The un-supercharged output is un-measured and would only be a rough guess. B. At the cruise altitude. The power output at any other altitude is somewhat different. Does the model understand variations of power with altitude? Now that I know that it is the un-supercharged number, I think I can adjust the number empirically to give a reasonable value. The cruise numbers - typo here I'm afraid: 1140 HP would be the right number. I've changed these so many times . 4x was just grabbed out of the air, but since the Boost Control Valve is open in the real aircraft up to 25000 ft or so, this didn't seem to matter. I was going to adjust this number in due course to try to model the proper boost curve. The takeoff values. Are these the power absorbed by the propeller at propeller rpm, or the engine output at engine rpm, super- or un-supercharged? Finally, I've had some difficulty understanding the concept of using absolute pressure for the Boost Control Valve (BCV). In the real world a BCV comprises, in principle, a plate exposed to manifold pressure on one side and to the local atmospheric pressure on the other and held closed by a spring which opens at the designed boost pressure (in this case 9 psi adjustable by the pilot to allow 12.5 psi for up to 5 mins), and is thus corrected for altitude. I've been scratching through the code, and can't confirm that YASim models this behaviour. Perhaps I don't need to bother? And I haven't even tackled the constant speed propeller! I suppose that we should update the documentation to reflect these misinterpretations. Thanks for your help. We'll have a Spitfire with a Merlin engine yet! Vivian Meazza ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
RE: [Flightgear-devel] Spitfire Hurricane manuals
On 4/19/04 at 9:24 AM Vivian Meazza wrote: Finally, I've had some difficulty understanding the concept of using absolute pressure for the Boost Control Valve (BCV). In the real world a BCV comprises, in principle, a plate exposed to manifold pressure on one side and to the local atmospheric pressure on the other and held closed by a spring which opens at the designed boost pressure (in this case 9 psi adjustable by the pilot to allow 12.5 psi for up to 5 mins), and is thus corrected for altitude. I've been scratching through the code, and can't confirm that YASim models this behaviour. Perhaps I don't need to bother? My understanding of it is that at rated throttle position, the boost control attempts to maintain sea-level-ambient-pressure + 9psi boost, approximately 42inHg manifold absolute pressure (MAP), regardless of altitude. This is well within the supercharger rating at sea-level, since its designed for altitude, and the BCV is controlling the pressure. As the plane climbs, the BCV maintains the 42 inHg MAP (if the rated-boost throttle position is maintained) until an altitude is reached at which the full supercharger output is being used to maintain 42in, and from then on MAP falls as height is gained. Thus the BCV is attempting to maintain an absolute pressure, not local-pressure + boost. I don't know how it works though - I had assumed it would have a sealed sea-level-ambient-pressure chamber at one side and MAP at the other, but that's just a guess. Can anyone clarify the function of the Boost cut-out EMERGENCY control mentioned in the manual. The name implies that it cuts the boost completely in an engine emergency. However, the text implies that it overrides the BCV for extra emergency boost: If it is desired in an emergency to override the automatic boost control, this control can be cut-out by pushing forward the small red-painted lever (14) at the forward end of the throttle quadrant. The lever is sealed as a check against inadvertant operation. Can anyone confirm either one or other of the possible functions of this? Cheers - Dave This message has been scanned but we cannot guarantee that it and any attachments are free from viruses or other damaging content: you are advised to perform your own checks. Email communications with the University of Nottingham may be monitored as permitted by UK legislation. ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Spitfire Hurricane manuals
Vivian Meazza wrote: The takeoff values. Are these the power absorbed by the propeller at propeller rpm, or the engine output at engine rpm, super- or un-supercharged? Un-supercharged. And the equations are solved such that both power values are the same. Basically, don't sweat this one; it affects performance only at the very start of the takeoff roll. Leave it out until you get things working, and then start fiddling with it to get the initial RPM right. Finally, I've had some difficulty understanding the concept of using absolute pressure for the Boost Control Valve (BCV). In the real world a BCV comprises [...] and is thus corrected for altitude. Actually, everything I've read indicates that wastegate designs are calibrated to absolute pressure, not relative pressure (which makes sense, obviously, because what you are trying to regulate is the force on the engine parts, not the overpressure in the manifold which is a non-critical structural part). Measuring absolute pressure is mechanically more difficult but not impossible. It doesn't have to be as simple as a single spring valve. I suppose that we should update the documentation to reflect these misinterpretations. Roger. See if what's there now makes more sense. Andy ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
RE: [Flightgear-devel] Spitfire Hurricane manuals
-Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of David Luff Sent: 19 April 2004 09:52 To: FlightGear developers discussions Subject: RE: [Flightgear-devel] Spitfire Hurricane manuals On 4/19/04 at 9:24 AM Vivian Meazza wrote: Finally, I've had some difficulty understanding the concept of using absolute pressure for the Boost Control Valve (BCV). In the real world a BCV comprises, in principle, a plate exposed to manifold pressure on one side and to the local atmospheric pressure on the other and held closed by a spring which opens at the designed boost pressure (in this case 9 psi adjustable by the pilot to allow 12.5 psi for up to 5 mins), and is thus corrected for altitude. I've been scratching through the code, and can't confirm that YASim models this behaviour. Perhaps I don't need to bother? My understanding of it is that at rated throttle position, the boost control attempts to maintain sea-level-ambient-pressure + 9psi boost, approximately 42inHg manifold absolute pressure (MAP), regardless of altitude. This is well within the supercharger rating at sea-level, since its designed for altitude, and the BCV is controlling the pressure. As the plane climbs, the BCV maintains the 42 inHg MAP (if the rated-boost throttle position is maintained) until an altitude is reached at which the full supercharger output is being used to maintain 42in, and from then on MAP falls as height is gained. Thus the BCV is attempting to maintain an absolute pressure, not local-pressure + boost. I don't know how it works though - I had assumed it would have a sealed sea-level-ambient-pressure chamber at one side and MAP at the other, but that's just a guess. This seems to be correct. This is from a contemporary test of a Spitfire MkIIa: http://www.fourthfightergroup.com/eagles/p7280speed.gif Can anyone clarify the function of the Boost cut-out EMERGENCY control mentioned in the manual. The name implies that it cuts the boost completely in an engine emergency. However, the text implies that it overrides the BCV for extra emergency boost: If it is desired in an emergency to override the automatic boost control, this control can be cut-out by pushing forward the small red-painted lever (14) at the forward end of the throttle quadrant. The lever is sealed as a check against inadvertant operation. I think it was also known as the Boost Control Cut-out. These documents explain that your latter interpretation is correct: http://www.fourthfightergroup.com/eagles/spit1-12lbs.jpg http://www.fourthfightergroup.com/eagles/ap1590b.jpg http://www.fourthfightergroup.com/eagles/dowding1.jpg http://www.fourthfightergroup.com/eagles/dowding2.jpg Can anyone confirm either one or other of the possible functions of this? Cheers - Dave Regards Vivian ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Spitfire Hurricane manuals
I wrote (incorrectly): The eng setting is a maximum power (at standard sea level) for the engine without supercharging. Never mind the last part. The code *does* correctly handle the boost setting, and assumes that it is at maximum (in most cases, the wastegate setting) at the specified power. Andy ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Spitfire Hurricane manuals
Andy Ross said: These settings don't make much sense in combination. The eng setting is a maximum power (at standard sea level) for the engine without supercharging. In this case, the normally aspirated engine develops 1140 HP at max RPM. That needs to be clarified in the docs (the part about without supercharging). I know it should be obvious, but the way the solver works with other values it is reasonable to assume the max power is max power, not max power w/o supercharger. Also IIRC the only specs available for the Merlin were with the supercharger. Possibly there are some older models that could be used, but I'm not sure if there was one that went into production w/o at least turbo. In any case this sheds some light on a few problems I had modeling the p51d. Best, Jim ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
RE: [Flightgear-devel] Spitfire Hurricane manuals
David Luff said: Can anyone clarify the function of the Boost cut-out EMERGENCY control mentioned in the manual. The name implies that it cuts the boost completely in an engine emergency. However, the text implies that it overrides the BCV for extra emergency boost: If it is desired in an emergency to override the automatic boost control, this control can be cut-out by pushing forward the small red-painted lever (14) at the forward end of the throttle quadrant. The lever is sealed as a check against inadvertant operation. Can anyone confirm either one or other of the possible functions of this? Cheers - Dave That quote actually makes sense to some degree. The term I've seen used is war emergency power which is basically just used to escape a bad under fire situation. You are given 7 minutes of it IIRC. But the automatic boost control I do not understand. The supercharger is described as two staged, but what you are suggesting is that each stage is automatically and continuously adjusted through some sort of relief to maintain sea level pressure. In contrast, my take was the second stage kicked in automatically at a particular altitude or ambient pressure (note this is manual in our p51d model). The purpose being to step up the pressure to make it possible to maintain normal sea level operating conditions (a gross adjustment that is). The p51d cockpit comes with a manifold/throttle lever, so I guess my questions is, if I am wrong, how does such an automatic control work? I have access to a real live p51d pilot via email so if we can get questions together I can probably forward them and get some answers. Note however I will be out of town for a few days starting tomorrow, so there could be a delay. Best, Jim ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Spitfire Hurricane manuals
Jim Wilson writes: David Luff said: Can anyone clarify the function of the Boost cut-out EMERGENCY control mentioned in the manual. The name implies that it cuts the boost completely in an engine emergency. However, the text implies that it overrides the BCV for extra emergency boost: If it is desired in an emergency to override the automatic boost control, this control can be cut-out by pushing forward the small red-painted lever (14) at the forward end of the throttle quadrant. The lever is sealed as a check against inadvertant operation. Can anyone confirm either one or other of the possible functions of this? Cheers - Dave That quote actually makes sense to some degree. The term I've seen used is war emergency power which is basically just used to escape a bad under fire situation. You are given 7 minutes of it IIRC. But the automatic boost control I do not understand. The supercharger is described as two staged, but what you are suggesting is that each stage is automatically and continuously adjusted through some sort of relief to maintain sea level pressure. To maintain sea-level-pressure *plus* a certain boost level mandated by the throttle position - eg 29.92 + ~13 = ~42inHg for the 9psi (~13inHg) rated boost (throttle position just before the take-off position gate) of the Merlin XII. In contrast, my take was the second stage kicked in automatically at a particular altitude or ambient pressure (note this is manual in our p51d model). The purpose being to step up the pressure to make it possible to maintain normal sea level operating conditions (a gross adjustment that is). The p51d cockpit comes with a manifold/throttle lever, so I guess my questions is, if I am wrong, how does such an automatic control work? I have access to a real live p51d pilot via email so if we can get questions together I can probably forward them and get some answers. Note however I will be out of town for a few days starting tomorrow, so there could be a delay. I think the engine described in the manuals (Merlin XII) was fitted with a single speed supercharger, whereas the engine in the p51d (Merlin 61 or Packard equivalent) had a two-speed supercharger. For each speed of the Merlin 61 the automatic boost control would try to maintain a given absolute pressure (I think). I've got a graph of power vs. altitude for a typical WWII 2 speed supercharger in a book somewhere. The power rises slightly from sea level to about 1 ft as the exhaust backpressure drops. It then starts to drop more steeply as the boost from the first speed reaches it's limit. The after a small drop the switch to the second speed is made, and the power rises slightly again with altitude until the second stage boost limit is reached, at which point it drops off steadily with altitude. Note that the switchover altitude is higher than that at which peak 1st speed power is made after the power has dropped off slightly - this is because the higher supercharger speed at speed 2 requires more engine power to drive it and the switch is made at the crossover of the two powers. Thus there are actually two local maxima in the power vs. altitude trace. I had wondered about your Ctrl-b to switch over - all the references I can find have it as automatic. Note also that the Merlin 61 is often described as having 2-speed, 2-stage supercharging. In this case the supercharger is phyically made of two separate stages. However, this is an engineering issue transparent to the pilot. It is the 2 supercharger drive speeds that are switched by the switchover valve, and within each of those discreet speeds the automatic boost control attempts to maintain constant MAP. I *think* - I'm quite open to correction on all these points! You can take it from this that supercharging in JSBSim is fairly imminent BTW ;-) And I'll have to take my leave from this discussion shortly - I'm imminently off to the expo... Cheers - Dave ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
RE: [Flightgear-devel] Spitfire Hurricane manuals
David Luff said Jim Wilson writes: David Luff said: Can anyone clarify the function of the Boost cut-out EMERGENCY control mentioned in the manual. The name implies that it cuts the boost completely in an engine emergency. However, the text implies that it overrides the BCV for extra emergency boost: If it is desired in an emergency to override the automatic boost control, this control can be cut-out by pushing forward the small red-painted lever (14) at the forward end of the throttle quadrant. The lever is sealed as a check against inadvertant operation. Can anyone confirm either one or other of the possible functions of this? Cheers - Dave That quote actually makes sense to some degree. The term I've seen used is war emergency power which is basically just used to escape a bad under fire situation. You are given 7 minutes of it IIRC. But the automatic boost control I do not understand. The supercharger is described as two staged, but what you are suggesting is that each stage is automatically and continuously adjusted through some sort of relief to maintain sea level pressure. To maintain sea-level-pressure *plus* a certain boost level mandated by the throttle position - eg 29.92 + ~13 = ~42inHg for the 9psi (~13inHg) rated boost (throttle position just before the take-off position gate) of the Merlin XII. In contrast, my take was the second stage kicked in automatically at a particular altitude or ambient pressure (note this is manual in our p51d model). The purpose being to step up the pressure to make it possible to maintain normal sea level operating conditions (a gross adjustment that is). The p51d cockpit comes with a manifold/throttle lever, so I guess my questions is, if I am wrong, how does such an automatic control work? I have access to a real live p51d pilot via email so if we can get questions together I can probably forward them and get some answers. Note however I will be out of town for a few days starting tomorrow, so there could be a delay. I think the engine described in the manuals (Merlin XII) was fitted with a single speed supercharger, whereas the engine in the p51d (Merlin 61 or Packard equivalent) had a two-speed supercharger. For each speed of the Merlin 61 the automatic boost control would try to maintain a given absolute pressure (I think). I've got a graph of power vs. altitude for a typical WWII 2 speed supercharger in a book somewhere. The power rises slightly from sea level to about 1 ft as the exhaust backpressure drops. It then starts to drop more steeply as the boost from the first speed reaches it's limit. The after a small drop the switch to the second speed is made, and the power rises slightly again with altitude until the second stage boost limit is reached, at which point it drops off steadily with altitude. Note that the switchover altitude is higher than that at which peak 1st speed power is made after the power has dropped off slightly - this is because the higher supercharger speed a t speed 2 requires more engine power to drive it and the switch is made at the crossover of the two powers. Thus there are actually two local maxima in the power vs. altitude trace. I had wondered about your Ctrl-b to switch over - all the references I can find have it as automatic. Note also that the Merlin 61 is often described as having 2-speed, 2-stage supercharging. In this case the supercharger is phyically made of two separate stages. However, this is an engineering issue transparent to the pilot. It is the 2 supercharger drive speeds that are switched by the switchover valve, and within each of those discreet speeds the automatic boost control attempts to maintain constant MAP. I *think* - I'm quite open to correction on all these points! You can take it from this that supercharging in JSBSim is fairly imminent BTW ;-) And I'll have to take my leave from this discussion shortly - I'm imminently off to the expo... Cheers - Dave All you ever wanted to know about a Merlin with 2 speed, 2 stage supercharging is here: http://www.unlimitedexcitement.com/Pride%20of%20Pay%20n%20Pak/Rolls-Royce%20 Merlin%20V-1650%20Engine.htm Except exactly how the boost contol valve worked :-) Regards Vivian Meazza ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
RE: [Flightgear-devel] Spitfire Hurricane manuals
Andy Ross wrote Vivian Meazza wrote: The takeoff values. Are these the power absorbed by the propeller at propeller rpm, or the engine output at engine rpm, super- or un-supercharged? Un-supercharged. And the equations are solved such that both power values are the same. Basically, don't sweat this one; it affects performance only at the very start of the takeoff roll. Leave it out until you get things working, and then start fiddling with it to get the initial RPM right. Finally, I've had some difficulty understanding the concept of using absolute pressure for the Boost Control Valve (BCV). In the real world a BCV comprises [...] and is thus corrected for altitude. Actually, everything I've read indicates that wastegate designs are calibrated to absolute pressure, not relative pressure (which makes sense, obviously, because what you are trying to regulate is the force on the engine parts, not the overpressure in the manifold which is a non-critical structural part). Measuring absolute pressure is mechanically more difficult but not impossible. It doesn't have to be as simple as a single spring valve. I suppose that we should update the documentation to reflect these misinterpretations. Roger. See if what's there now makes more sense. Andy I think I might be getting somewhere. First I started with these values: eng-power=1140 eng-rpm=2850 turbo-mul=4 wastegate-mp=48 cruise-alt=17500 cruise-power=1140 cruise-speed=308 cruise-rpm=2850 takeoff-power=900 takeoff-rpm=2500 manual-pitch=true gear-ratio = 0.477 AS before, YASim converges nicely However, eng-power should be the un-supercharged max power, so I reduced eng-power value, while holding all others constant. YASim only converged with a eng-power = 1130. This cannot be the un-supercharged max power? I then set eng-pwr to 1140, and tried reducing turbo-mul. YASim only converged with turbo-mul =3.5 I next set turbo-mul to 4, and tried reducing cruise-rpm. YASim only converged with cruise-rpm 2820. I then tried increasing cruise-rpm. YASim only converges with cruise-rpm 6799. Is it possible that reduction gearing reduces engine revs for a given propeller rpm? I thought it was the other way around. So assuming this to be the case, I set cruise-rpm to 5975, and repeated the above sequence. YASim converges when: eng-power =575 turbo-mul =0.0001 In each case the other value is set with the initial value as above. Now, assuming a turbo-mul value of 2 as a reasonable guess, and 750 HP as the un-supercharged output, we get this: eng-power=750 eng-rpm=2850 turbo-mul=2 wastegate-mp=48 cruise-alt=17500 cruise-power=1140 cruise-speed=308 cruise-rpm=5975 takeoff-power=725 takeoff-rpm=5000 manual-pitch=true gear-ratio = 0.477 YASim converges nicely. Problem solved? Regards Vivian Meazza ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Spitfire Hurricane manuals
While I remember, if a YASim a/c only has one tank, the second tank - tank[1] - seems to be set with a 'nan' level. Doesn't stop the a/c engine from starting or running but it screws up the tot fuel figure. Setting the level for tank[1] to zero via the property browser sorts it ok. LeeE ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Spitfire Hurricane manuals
Lee Elliott wrote: While I remember, if a YASim a/c only has one tank, the second tank - tank[1] - seems to be set with a 'nan' level. Doesn't stop the a/c engine from starting or running but it screws up the tot fuel figure. Setting the level for tank[1] to zero via the property browser sorts it ok. Hrm... The initialization conditions for the first two tanks were a little touchy (there are still some hardwired assumptions about 2 tanks in the code), but I was pretty sure I got it all figured out. Which aircraft is showing this problem? Andy ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Spitfire Hurricane manuals
On Tuesday 20 April 2004 01:58, Andy Ross wrote: Lee Elliott wrote: While I remember, if a YASim a/c only has one tank, the second tank - tank[1] - seems to be set with a 'nan' level. Doesn't stop the a/c engine from starting or running but it screws up the tot fuel figure. Setting the level for tank[1] to zero via the property browser sorts it ok. Hrm... The initialization conditions for the first two tanks were a little touchy (there are still some hardwired assumptions about 2 tanks in the code), but I was pretty sure I got it all figured out. Which aircraft is showing this problem? Andy I'm getting it on the ComperSwift - afaik it only has a single 15 gal tank. It looks like a hardwired sort of issue but as I said it's easily fixed by specifying 0 for the level in the browser (don't need to set the tanks as un-selected now:) LeeE ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Spitfire Hurricane manuals
Vivian Meazza wrote: YASim crashes, or perhaps, fails to converge, just by attempting to run with takeoff-power=1100 takeoff-rpm=1360 Crashing and solution failure ought to be easily distinguished. :) Maybe the recent logging changes have hidden the failure message, I'll take a look. Try running the command line yasim program on your XML file. It will give you a solution (and print the report) result much faster than a full fgfs invocation. I'll take a look at the file as soon as I can. Andy ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
RE: [Flightgear-devel] Spitfire Hurricane manuals
Andy Ross wrote: Sent: 18 April 2004 19:04 To: FlightGear developers discussions Subject: Re: [Flightgear-devel] Spitfire Hurricane manuals Vivian Meazza wrote: YASim crashes, or perhaps, fails to converge, just by attempting to run with takeoff-power=1100 takeoff-rpm=1360 Crashing and solution failure ought to be easily distinguished. :) Maybe the recent logging changes have hidden the failure message, I'll take a look. Try running the command line YASim program on your XML file. It will give you a solution (and print the report) result much faster than a full fgfs invocation. I'll take a look at the file as soon as I can. Andy Thank you for drawing my attention to that utility. Using these values: propeller x=-1.10 y=0 z=0 radius=1.638 moment=37.15 mass=2000 eng-power=1140 eng-rpm=2850 turbo-mul=4.0 wastegate-mp=28 cruise-alt=17500 cruise-power=2850 cruise-speed=308 cruise-rpm=2850 takeoff-power=1100 takeoff-rpm=2850 manual-pitch=true gear-ratio = 0.477 YASim converges nicely. With these values propeller x=-1.10 y=0 z=0 radius=1.638 moment=37.15 mass=2000 eng-power=1140 eng-rpm=2850 turbo-mul=4.0 wastegate-mp=28 cruise-alt=17500 cruise-power=2850 cruise-speed=308 cruise-rpm=1359 takeoff-power=1100 takeoff-rpm=1359 manual-pitch=true gear-ratio = 0.477 YASim appears go into a loop and provides no output. The only way out is to shut down Cygwin. Vivian ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Spitfire Hurricane manuals
On Sunday 18 April 2004 22:46, Vivian Meazza wrote: Andy Ross wrote: Sent: 18 April 2004 19:04 To: FlightGear developers discussions Subject: Re: [Flightgear-devel] Spitfire Hurricane manuals Vivian Meazza wrote: YASim crashes, or perhaps, fails to converge, just by attempting to run with takeoff-power=1100 takeoff-rpm=1360 Crashing and solution failure ought to be easily distinguished. :) Maybe the recent logging changes have hidden the failure message, I'll take a look. Try running the command line YASim program on your XML file. It will give you a solution (and print the report) result much faster than a full fgfs invocation. I'll take a look at the file as soon as I can. Andy Thank you for drawing my attention to that utility. Using these values: propeller x=-1.10 y=0 z=0 radius=1.638 moment=37.15 mass=2000 eng-power=1140 eng-rpm=2850 turbo-mul=4.0 wastegate-mp=28 cruise-alt=17500 cruise-power=2850 cruise-speed=308 cruise-rpm=2850 takeoff-power=1100 takeoff-rpm=2850 manual-pitch=true gear-ratio = 0.477 YASim converges nicely. With these values propeller x=-1.10 y=0 z=0 radius=1.638 moment=37.15 mass=2000 eng-power=1140 eng-rpm=2850 turbo-mul=4.0 wastegate-mp=28 cruise-alt=17500 cruise-power=2850 cruise-speed=308 cruise-rpm=1359 takeoff-power=1100 takeoff-rpm=1359 manual-pitch=true gear-ratio = 0.477 YASim appears go into a loop and provides no output. The only way out is to shut down Cygwin. Vivian I've experienced similar 'looping' behaviour when trying to get propellers working properly. Don't know why though - never seems to happen with jet aircraft. Just taking a quick look at the propeller definitions above, it looks as though you're specifying the eng-rpm value for the cruise-power entry in both cases (2850) - what happens if you use 1100? (this being the same value you use for the takeoff-power - the takeoff-rpm and the cruise-rpm match in the definition) LeeE ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Spitfire Hurricane manuals
Vivian Meazza wrote: With these values eng-power=1140 eng-rpm=2850 cruise-power=2850 cruise-rpm=1359 takeoff-power=1100 takeoff-rpm=1359 YASim appears go into a loop and provides no output. These settings don't make much sense in combination. The eng setting is a maximum power (at standard sea level) for the engine without supercharging. In this case, the normally aspirated engine develops 1140 HP at max RPM. The cruise numbers are used to fix the propeller's maximum efficiency peak. The propeller you are using wants to sink 2850 HP (more than double max sea level power) at less than half (!) of the engine's max RPM. Even with 4x supercharging (which sounds kinda high to me, but I'm not an expert), that's just not going to work. Are you working from POH numbers for this engine that might be typoed or misinterpreted? The takeoff values correspond to the power and RPM developed by the aircraft at max throttle and zero airspeed. It's there because propellers have funny, non-linear behavior in the very low pitch regime (when the blades are partially stalled). The default model produces strange results here, so the FDM allows you specify a clamp to match real-world behavior. It's not important to the solver, or for in-flight performance. I'll look into the apparent infinite loop behavior. Andy ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
RE: [Flightgear-devel] Spitfire Hurricane manuals
Andy Ross wrote Vivian Meazza wrote: How do we set the reduction gearing ratio? Set the gear-ratio attribute of the propeller tag. This is the reduction ratio, so typical values will be less than 1.0. Can we do a constant speed propeller? The min-rpm and max-rpm attributes define the range of the blue lever. These are the speeds to which the propeller will seek; it may not be able to achieve them in practice. The documentation for these was, er, wrong. I'll fix that. And can we set the handedness of the propeller to RH? Sure thing. Use a negative moment value. :) No joke: that will have exactly the effect of a counter-rotating engine. The DC-3 uses this trick for the starboard engine, for example. I'll add some documentation for that as well. Andy I have almost finished the Spitfire model. Texturing, animation and a 3d cockpit remain to do. However, I am having some difficulty with the engine reduction gear ratio. I've used using the following numbers which give a reasonable solution in YASim. propeller x=-1.10 y=0 z=0 radius=1.638 moment=37.15 mass=2000 eng-power=1140 eng-rpm=2850 turbo-mul=4.0 wastegate-mp=18.32 cruise-alt=17500 cruise-power=1100 cruise-speed=308 cruise-rpm=2850 takeoff-power=1100 takeoff-rpm=2850 manual-pitch=true actionpt x=-0.75 y=0 z=0/ control-input axis=/controls/engines/engine[0]/propeller-pitch control=PROPPITCH src0=0 src1=1 dst0=0.1 dst1=0.6/ /propeller The model flies reasonably well, with the following output data when throttle = 1: max-hp = 1140.491452 mp-osi = 26.050 - does the wastegate work? - is this psi? power-pct = 105.863353 prop-thrust = 1314.603118 rpm = 3014.603118 I've kept to manual pitch control for now. I've tried this, although I would think, incorrectly: propeller x=-1.10 y=0 z=0 radius=1.638 moment=37.15 mass=2000 eng-power=1140 eng-rpm=2850 turbo-mul=4.0 wastegate-mp=18.32 cruise-alt=17500 cruise-power=1100 cruise-speed=308 cruise-rpm=2850 takeoff-power=1100 takeoff-rpm=2850 manual-pitch=true gear-ratio = 0.477 actionpt x=-0.75 y=0 z=0/ control-input axis=/controls/engines/engine[0]/propeller-pitch control=PROPPITCH src0=0 src1=1 dst0=0.1 dst1=0.6/ /propeller The model still flies reasonably well, with the following output data when throttle = 1: max-hp = 1140.491452 mp-osi = 29.729 - does the wastegate work? - is this psi? power-pct = 222.856 prop-thrust = 1375.645173 rpm = 6176.318088 - this is wrong Finally, I tried this: propeller x=-1.10 y=0 z=0 radius=1.638 moment=37.15 mass=2000 eng-power=1140 eng-rpm=2850 turbo-mul=4.0 wastegate-mp=18.32 cruise-alt=17500 cruise-power=1100 cruise-speed=308 cruise-rpm=1360 takeoff-power=1100 takeoff-rpm=2850 manual-pitch=true gear-ratio = 0.477 control-input axis=/controls/engines/engine[0]/propeller-pitch control=PROPPITCH src0=0 src1=1 dst0=0.1 dst1=0.6/ /propeller The model does not fly, failing to accelerate (insufficient prop thrust), with the following output data when throttle = 1: max-hp = 1140.491452 mp-osi = 29.729 power-pct = 225.856 - wrong prop-thrust = 659.082929 - wrong rpm = 6232.318088 - even more wrong I've tried increasing pitch, to no avail. I've tried takeoff-power=1100 takeoff-rpm=1360 - then YASim crashes What is the obvious mistake that I am making? Regards Vivian Meazza ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Spitfire Hurricane manuals
Vivian Meazza wrote: wastegate-mp=18.32 [...] mp-osi = 26.050 - does the wastegate work? - is this psi? The units are absolute pressure in inches of mercury (I honestly don't know what the -osi suffix means). The wastegate should indeed work. However, it is an overpressure release valve. It cannot suck a vacuum in the manifold if ambient pressure is already higher than its setting. :) Typical values for the wastegate are going to be significantly higher than one atmosphere (== ~28 Hg), but I'm sure that varies with supercharger design. Probably some aircraft don't have them at all. The model does not fly, failing to accelerate (insufficient prop thrust), with the following output data when throttle = 1: Outside the wastegate setting (which is a noop in this case) nothing looks clearly incorrect. Can you post the whole file so I can try it? I've tried increasing pitch, to no avail. I've tried takeoff-power=1100 takeoff-rpm=1360 - then YASim crashes That's clearly a bug; no configuration should be causing crashes*. Can you be more specific about how to reproduce it? Andy * Well, not quite: you can crash YASim by mapping a property to an incorrect object -- THROTTLE on a wing, for example. It should check for validity at parse time, but doesn't. ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
RE: [Flightgear-devel] Spitfire Hurricane manuals
Andy Ross replied Vivian Meazza wrote: wastegate-mp=18.32 [...] mp-osi = 26.050 - does the wastegate work? - is this psi? The units are absolute pressure in inches of mercury (I honestly don't know what the -osi suffix means). The wastegate should indeed work. However, it is an overpressure release valve. It cannot suck a vacuum in the manifold if ambient pressure is already higher than its setting. :) Typical values for the wastegate are going to be significantly higher than one atmosphere (== ~28 Hg), but I'm sure that varies with supercharger design. Probably some aircraft don't have them at all. The model does not fly, failing to accelerate (insufficient prop thrust), with the following output data when throttle = 1: Outside the wastegate setting (which is a noop in this case) nothing looks clearly incorrect. Can you post the whole file so I can try it? I've tried increasing pitch, to no avail. I've tried takeoff-power=1100 takeoff-rpm=1360 - then YASim crashes That's clearly a bug; no configuration should be causing crashes*. Can you be more specific about how to reproduce it? Andy * Well, not quite: you can crash YASim by mapping a property to an incorrect object -- THROTTLE on a wing, for example. It should check for validity at parse time, but doesn't. Osi - ounces per sq in :-) more likely a typo for psi. I'm just going to try the wastegate (or, more strictly, boost control valve) using absolute pressure. Slightly odd, that, manifold pressures are usually referred to as overpressure. YASim crashes, or perhaps, fails to converge, just by attempting to run with takeoff-power=1100 takeoff-rpm=1360 Thanks for the quick response. Vivian Meazza ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
RE: [Flightgear-devel] Spitfire Hurricane manuals
Andy Ross wrote Vivian Meazza wrote: wastegate-mp=18.32 [...] mp-osi = 26.050 - does the wastegate work? - is this psi? The units are absolute pressure in inches of mercury (I honestly don't know what the -osi suffix means). The wastegate should indeed work. However, it is an overpressure release valve. It cannot suck a vacuum in the manifold if ambient pressure is already higher than its setting. :) Typical values for the wastegate are going to be significantly higher than one atmosphere (== ~28 Hg), but I'm sure that varies with supercharger design. Probably some aircraft don't have them at all. The model does not fly, failing to accelerate (insufficient prop thrust), with the following output data when throttle = 1: Outside the wastegate setting (which is a noop in this case) nothing looks clearly incorrect. Can you post the whole file so I can try it? Here's the whole file as requested: ?xml version=1.0? !-- YASim aerodynamic model for a Spitfire IIa The reference datum for measurements is the nose. -- !-- Weight of everything but fuel (4873 empty) -- airplane mass=5200 !-- Approach configuration -- approach speed=75 aoa=13 control-setting axis=/controls/engines/engine[0]/throttle value=0.2/ control-setting axis=/controls/engines/engine[0]/mixture value=1.0/ control-setting axis=/controls/engines/engine[0]/propeller-pitch value=0.2/ control-setting axis=/controls/engines/engine[0]/boost value=0.25/ control-setting axis=/controls/flight/flaps value=1.0/ control-setting axis=/controls/gear/gear-down value=1/ /approach !-- Cruise configuration -- cruise speed=308 alt=17500 control-setting axis=/controls/engines/engine[0]/throttle value=0.90/ control-setting axis=/controls/engines/engine[0]/mixture value=1.00/ control-setting axis=/controls/engines/engine[0]/propeller-pitch value=1.0/ control-setting axis=/controls/engines/engine[0]/boost value=1/ control-setting axis=/controls/flight/flaps value=0.0/ control-setting axis=/controls/gear/gear-down value=0/ /cruise !-- pilot's eye point -- cockpit x=-3.86 y=0 z=0.55/ fuselage ax=0.0 ay=0.0 az=0.0 bx=-9.13 by=0.0 bz=0.0 width=0.94 taper=0.38 midpoint=0.4 / !-- stall aoa not available flap drag not available -- wing x=-2.99 y=0.77 z=-0.81 taper=0.3 incidence=2 twist=-2.0 length=4.576 chord=2.845 sweep=-3.5 dihedral=6 stall aoa=20 width=4 peak=1.5/ flap0 start=0.00 end=0.437 lift=1.3 drag=1.8/ flap1 start=0.437 end=0.90 lift=1.2 drag=1.2/ control-input axis=/controls/flight/flaps control=FLAP0/ control-output control=FLAP0 prop=/surface-positions/flap-pos-norm/ control-speed control=FLAP0 transition-time=5/ control-input axis=/controls/flight/aileron control=FLAP1 split=true/ control-input axis=/controls/flight/aileron-trim control=FLAP1 split=true/ /wing !-- tailplanee -- hstab x=-8.22 y=0.25 z=0.0 taper=0.639 effectiveness=2 length=1.215 chord=1.246 sweep=5 stall aoa=24 width=4 peak=1.5/ flap0 start=0.0 end=1 lift=1.65 drag=1.5/ control-input axis=/controls/flight/elevator control=FLAP0/ control-input axis=/controls/flight/elevator-trim control=FLAP0/ control-output control=FLAP0 prop=/surface-positions/elevator-pos-norm/ /hstab !-- tail -- vstab x=-8.52 y=0 z=-0.29 taper=0.386 effectiveness=2 length=1.598 chord=0.994 sweep=5 stall aoa=15 width=4 peak=1.5/ flap0 start=0 end=1 lift=1.65 drag=1.5/ control-input axis=/controls/flight/rudder square=true control=FLAP0 invert=true/ control-input axis=/controls/flight/rudder-trim control=FLAP0 invert=true/ control-output control=FLAP0 prop=/surface-positions/rudder-pos-norm min=1 max=-1/ /vstab !-- wastegate setting should not apply. set here so that calculations would approximate. YASim doesn't model gear supercharger. Have read various figures (turbo-mul) 4.0 to 5.8 for running the second stage blower. Fixing this would probably give more reasonable performance at lower altitude -- !-- moment = radius(m)* propeller mass(kg)/2 - equation provided by Andy Ross -- !-- cruise-rpm documented gear ratio of 0.479 min-rpm=600 max-rpm=3000-- propeller x=-1.10 y=0 z=0 radius=1.638 moment=37.15 mass=2000 eng-power=1140 eng-rpm=2850 turbo-mul=4.0 wastegate-mp=48.2454 cruise-alt=17500 cruise-power=1100 cruise-speed=308 cruise-rpm=2850 takeoff-power=1100 takeoff-rpm=2850 manual-pitch=true gear-ratio = 0.477 actionpt x=-0.75 y=0 z=0/ control-input axis=/controls/engines/engine[0]/throttle control=THROTTLE/ control-input
RE: [Flightgear-devel] Spitfire Hurricane manuals
Jonathan Richards On Wednesday 31 Mar 2004 11:09 am, Vivian Meazza wrote: snip I now have the Spitfire IIa model well underway. I have all the drawings and data I need (far too much probably). I've rather lost the bubble on the recent changes to the piston engine simulation in YASim: Vivian The pictures here http://www.raf.mod.uk/news/limage_bbmf.html appeared on our intranet and I thought you might find them useful. 'Desert Spitfire' clearly has a four-bladed propeller, while 'Spitfire Head-On' is equally clearly three-bladed. There's some good detailed views for modellers, though. Regards Jonathan Great pics. They're sure to come in useful. Not sure about the Desert Spitfire - I think it ought to have the sand filter under the nose. Thanks Vivian Meazza ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Spitfire Hurricane manuals
On Wednesday 31 Mar 2004 11:09 am, Vivian Meazza wrote: snip I now have the Spitfire IIa model well underway. I have all the drawings and data I need (far too much probably). I've rather lost the bubble on the recent changes to the piston engine simulation in YASim: Vivian The pictures here http://www.raf.mod.uk/news/limage_bbmf.html appeared on our intranet and I thought you might find them useful. 'Desert Spitfire' clearly has a four-bladed propeller, while 'Spitfire Head-On' is equally clearly three-bladed. There's some good detailed views for modellers, though. Regards Jonathan ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Spitfire Hurricane manuals
On Thu, 1 Apr 2004 08:47:15 +0100, Vivian wrote in message [EMAIL PROTECTED]: Arnt Karlsen wrote On Wed, 31 Mar 2004 13:32:39 -0800, Andy wrote in message [EMAIL PROTECTED]: Vivian Meazza wrote: Thanks for all that: all looks good - the documentation has got a bit astern of station. Could you explain a bit more about the turbo attribute when used for a supercharger? Actually, the existing turbo-mul implementation is *more* like a supercharger than a real turbo. YASim models the boost as a simply multiplication factor on the input manifold pressure. If it's set to 2.0, then the engine sees twice the static pressure, etc... Real turbochargers don't have linear boost-vs-RPM curves, and tend to lag ..you mean lead? On pouring gas, the first thing to happen is the extra fuel spins up _only_ the turbo, which then promptly feeds engine more air etc as soon as that turbo is spun up. I don't think so. Turbo-lag is well known. The throttle opens, more fuel goes to the engine, which produces more exhaust gas which then speeds up the turbo-charger which increases air flow to the engine, hence the increase in inlet pressure lags the increase in engine rpm. ..for automobiles, I can agree, you floor it, then it hops. For the geared supercharger, you need to move all the iron around first. ..another thing is the sizing policy, in the air, you want good cruise performance and good altitude performance, and you don't wanna fry a dump valve if you can design it away. In an automobile, you need that dump valve and a giant turbine to turn that wee compressor, to get that marketing butt kick, and you get away with it because you cruise town at 5% between burnouts. (With stickshift, you don't.) ..for WWII combat planes, I can see compromises coming here. ..a geardriven supercharger is geared to the entire engine, and moves with the entire engine, and that too has to move around faster, before it can feed any more air. Whilst that is technically true, the increase in engine rpm brings an instantaneous increase in supercharger rpm and an instantaneous increase in output pressure. The only lag is caused in the ducting, which is usually kept as short as possible. For a supercharger, any lag can be ignored for practical purposes. ..this lag could easily be evaluated graphing rpm and manifold pressure etc against time. (in time) engine power by a little bit. A gear-driven supercharger is going to be closer to that ideal. Andy Regards Vivian Meazza -- ..med vennlig hilsen = with Kind Regards from Arnt... ;-) ...with a number of polar bear hunters in his ancestry... Scenarios always come in sets of three: best case, worst case, and just in case. ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
RE: [Flightgear-devel] Spitfire Hurricane manuals
Erik Hofman Sent: 13 March 2004 15:12 To: FlightGear developers discussions Subject: Re: [Flightgear-devel] Spitfire Hurricane manuals Erik Hofman wrote: http://home.clara.net/wolverine/BOB/misc/Spit_Hurri_Manuals.zip To get back to the original subject, this site has an aweful lot of information on WWII warbirds, including performance charts: http://www.rdrop.com/users/hoofj/ I now have the Spitfire IIa model well underway. I have all the drawings and data I need (far too much probably). I've rather lost the bubble on the recent changes to the piston engine simulation in YASim: How do we set the reduction gearing ratio? Can we do a constant speed propeller? And can we set the handedness of the propeller to RH? Regards Vivian Meazza ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Spitfire Hurricane manuals
On Wednesday 31 March 2004 11:09, Vivian Meazza wrote: Erik Hofman Sent: 13 March 2004 15:12 To: FlightGear developers discussions Subject: Re: [Flightgear-devel] Spitfire Hurricane manuals Erik Hofman wrote: http://home.clara.net/wolverine/BOB/misc/Spit_Hurri_Manuals.zip To get back to the original subject, this site has an aweful lot of information on WWII warbirds, including performance charts: http://www.rdrop.com/users/hoofj/ I now have the Spitfire IIa model well underway. I have all the drawings and data I need (far too much probably). I've rather lost the bubble on the recent changes to the piston engine simulation in YASim: How do we set the reduction gearing ratio? Can we do a constant speed propeller? And can we set the handedness of the propeller to RH? Regards Vivian Meazza Hello Vivian, I've used a geared prop in the Comper Swift - it seems to work well except the fuel mixture and flow rates don't seem correct. Can't help you with the CS prop though. Changing the handedness of the prop is easy enough as far as the animation goes but I think there's an assumption that all props rotate the same way as far as prop effects are concerned. LeeE ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Spitfire Hurricane manuals
Vivian Meazza wrote: How do we set the reduction gearing ratio? Set the gear-ratio attribute of the propeller tag. This is the reduction ratio, so typical values will be less than 1.0. Can we do a constant speed propeller? The min-rpm and max-rpm attributes define the range of the blue lever. These are the speeds to which the propeller will seek; it may not be able to achieve them in practice. The documentation for these was, er, wrong. I'll fix that. And can we set the handedness of the propeller to RH? Sure thing. Use a negative moment value. :) No joke: that will have exactly the effect of a counter-rotating engine. The DC-3 uses this trick for the starboard engine, for example. I'll add some documentation for that as well. Andy ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
RE: [Flightgear-devel] Spitfire Hurricane manuals
Andy Ross replied Sent: 31 March 2004 20:43 To: FlightGear developers discussions Subject: Re: [Flightgear-devel] Spitfire Hurricane manuals Vivian Meazza wrote: How do we set the reduction gearing ratio? Set the gear-ratio attribute of the propeller tag. This is the reduction ratio, so typical values will be less than 1.0. Can we do a constant speed propeller? The min-rpm and max-rpm attributes define the range of the blue lever. These are the speeds to which the propeller will seek; it may not be able to achieve them in practice. The documentation for these was, er, wrong. I'll fix that. And can we set the handedness of the propeller to RH? Sure thing. Use a negative moment value. :) No joke: that will have exactly the effect of a counter-rotating engine. The DC-3 uses this trick for the starboard engine, for example. I'll add some documentation for that as well. Thanks for all that: all looks good - the documentation has got a bit astern of station. Could you explain a bit more about the turbo attribute when used for a supercharger? The P51d uses this to calculate the moment: MOI = # of Blades * (8.2*(10^-5))*(D^5), slug-ft^2 then converted to kg-m^2 and finally square root to kg-m for torque value Is this the most up-to-date we have? Thanks again Vivian Meazza ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Spitfire Hurricane manuals
Vivian Meazza wrote: Thanks for all that: all looks good - the documentation has got a bit astern of station. Could you explain a bit more about the turbo attribute when used for a supercharger? Actually, the existing turbo-mul implementation is *more* like a supercharger than a real turbo. YASim models the boost as a simply multiplication factor on the input manifold pressure. If it's set to 2.0, then the engine sees twice the static pressure, etc... Real turbochargers don't have linear boost-vs-RPM curves, and tend to lag (in time) engine power by a little bit. A gear-driven supercharger is going to be closer to that ideal. MOI = # of Blades * (8.2*(10^-5))*(D^5), slug-ft^2 then converted to kg-m^2 and finally square root to kg-m for torque value Is D diameter? That looks like the right relationship (linear dimension to the fifth power) for a moment as a function of size, but I'd be *really* suspicious of using that equation for anything else. The .82 constant is pure fabrication, and will change depending on the shape and density (wood? aluminum? composite?) of any given propeller. A Lockheed Constellation and a Piper Cub sure as hell aren't going to have the same constant. :) Here's (IMHO) a better framework: Think of a propeller blade as a stick, with a constant density along its length. That's not quite right, but for most propellers the non-stickness is concentrated in the thick middle, which makes very little contribution to the moment of inertia. So the MOI is the integral along the blade length (from zero to R -- the propeller radius) of rho*r*dr, where rho (the density) is just propeller-[M]ass / ([N]umber-of-blades * R). So we do the integral for each blade and multiply by N: R M N * INTEGRAL --- * r * dr 0 N * R M, N and R come out as constants (and the N drops out entirely), so we have just a trivial: MR --- * INTEGRAL r * dr R0 Which of course is just (M/R) * (R^2/2) == M*R/2 So multiply your propeller mass (which you might have to guess at) by its radius and divide by two. Much simpler, and no magic constants needed. And you can do it in native units, without looking up what a slug is. :) Andy ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Spitfire Hurricane manuals
On Wed, 31 Mar 2004 13:32:39 -0800, Andy wrote in message [EMAIL PROTECTED]: Vivian Meazza wrote: Thanks for all that: all looks good - the documentation has got a bit astern of station. Could you explain a bit more about the turbo attribute when used for a supercharger? Actually, the existing turbo-mul implementation is *more* like a supercharger than a real turbo. YASim models the boost as a simply multiplication factor on the input manifold pressure. If it's set to 2.0, then the engine sees twice the static pressure, etc... Real turbochargers don't have linear boost-vs-RPM curves, and tend to lag ..you mean lead? On pouring gas, the first thing to happen is the extra fuel spins up _only_ the turbo, which then promptly feeds engine more air etc as soon as that turbo is spun up. ..a geardriven supercharger is geared to the entire engine, and moves with the entire engine, and that too has to move around faster, before it can feed any more air. (in time) engine power by a little bit. A gear-driven supercharger is going to be closer to that ideal. MOI = # of Blades * (8.2*(10^-5))*(D^5), slug-ft^2 then converted to kg-m^2 and finally square root to kg-m for torque value Is D diameter? That looks like the right relationship (linear dimension to the fifth power) for a moment as a function of size, but I'd be *really* suspicious of using that equation for anything else. The .82 constant is pure fabrication, and will change depending on the shape and density (wood? aluminum? composite?) of any given propeller. A Lockheed Constellation and a Piper Cub sure as hell aren't going to have the same constant. :) Here's (IMHO) a better framework: Think of a propeller blade as a stick, with a constant density along its length. That's not quite right, but for most propellers the non-stickness is concentrated in the thick middle, which makes very little contribution to the moment of inertia. So the MOI is the integral along the blade length (from zero to R -- the propeller radius) of rho*r*dr, where rho (the density) is just propeller-[M]ass / ([N]umber-of-blades * R). So we do the integral for each blade and multiply by N: R M N * INTEGRAL --- * r * dr 0 N * R M, N and R come out as constants (and the N drops out entirely), so we have just a trivial: MR --- * INTEGRAL r * dr R0 Which of course is just (M/R) * (R^2/2) == M*R/2 So multiply your propeller mass (which you might have to guess at) by its radius and divide by two. Much simpler, and no magic constants needed. And you can do it in native units, without looking up what a slug is. :) Andy -- ..med vennlig hilsen = with Kind Regards from Arnt... ;-) ...with a number of polar bear hunters in his ancestry... Scenarios always come in sets of three: best case, worst case, and just in case. ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
RE: [Flightgear-devel] Spitfire Hurricane manuals
Andy Ross wrote Vivian Meazza wrote: Thanks for all that: all looks good - the documentation has got a bit astern of station. Could you explain a bit more about the turbo attribute when used for a supercharger? Actually, the existing turbo-mul implementation is *more* like a supercharger than a real turbo. YASim models the boost as a simply multiplication factor on the input manifold pressure. If it's set to 2.0, then the engine sees twice the static pressure, etc... Real turbochargers don't have linear boost-vs-RPM curves, and tend to lag (in time) engine power by a little bit. A gear-driven supercharger is going to be closer to that ideal. MOI = # of Blades * (8.2*(10^-5))*(D^5), slug-ft^2 then converted to kg-m^2 and finally square root to kg-m for torque value Is D diameter? That looks like the right relationship (linear dimension to the fifth power) for a moment as a function of size, but I'd be *really* suspicious of using that equation for anything else. The .82 constant is pure fabrication, and will change depending on the shape and density (wood? aluminum? composite?) of any given propeller. A Lockheed Constellation and a Piper Cub sure as hell aren't going to have the same constant. :) Here's (IMHO) a better framework: Think of a propeller blade as a stick, with a constant density along its length. That's not quite right, but for most propellers the non-stickness is concentrated in the thick middle, which makes very little contribution to the moment of inertia. So the MOI is the integral along the blade length (from zero to R -- the propeller radius) of rho*r*dr, where rho (the density) is just propeller-[M]ass / ([N]umber-of-blades * R). So we do the integral for each blade and multiply by N: R M N * INTEGRAL --- * r * dr 0 N * R M, N and R come out as constants (and the N drops out entirely), so we have just a trivial: MR --- * INTEGRAL r * dr R0 Which of course is just (M/R) * (R^2/2) == M*R/2 So multiply your propeller mass (which you might have to guess at) by its radius and divide by two. Much simpler, and no magic constants needed. And you can do it in native units, without looking up what a slug is. :) Andy Like the math - D was diameter btw. How about embedding it in YASim? I have an accurate figure for the mass of the propeller. Slug: Unit of mass that is equal to the mass that takes 1 lbf to accelerate at 1 ft/s2 - that's the easy bit. Now on with the model until the next question. Thanks Vivian Meazza ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
RE: [Flightgear-devel] Spitfire Hurricane manuals
Arnt Karlsen wrote On Wed, 31 Mar 2004 13:32:39 -0800, Andy wrote in message [EMAIL PROTECTED]: Vivian Meazza wrote: Thanks for all that: all looks good - the documentation has got a bit astern of station. Could you explain a bit more about the turbo attribute when used for a supercharger? Actually, the existing turbo-mul implementation is *more* like a supercharger than a real turbo. YASim models the boost as a simply multiplication factor on the input manifold pressure. If it's set to 2.0, then the engine sees twice the static pressure, etc... Real turbochargers don't have linear boost-vs-RPM curves, and tend to lag ..you mean lead? On pouring gas, the first thing to happen is the extra fuel spins up _only_ the turbo, which then promptly feeds engine more air etc as soon as that turbo is spun up. I don't think so. Turbo-lag is well known. The throttle opens, more fuel goes to the engine, which produces more exhaust gas which then speeds up the turbo-charger which increases air flow to the engine, hence the increase in inlet pressure lags the increase in engine rpm. ..a geardriven supercharger is geared to the entire engine, and moves with the entire engine, and that too has to move around faster, before it can feed any more air. Whilst that is technically true, the increase in engine rpm brings an instantaneous increase in supercharger rpm and an instantaneous increase in output pressure. The only lag is caused in the ducting, which is usually kept as short as possible. For a supercharger, any lag can be ignored for practical purposes. (in time) engine power by a little bit. A gear-driven supercharger is going to be closer to that ideal. Andy Regards Vivian Meazza ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Spitfire Hurricane manuals
Erik Hofman wrote: http://home.clara.net/wolverine/BOB/misc/Spit_Hurri_Manuals.zip To get back to the original subject, this site has an aweful lot of information on WWII warbirds, including performance charts: http://www.rdrop.com/users/hoofj/ Erik ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Spitfire Hurricane manuals
Sorry I've not had the opportunity to reply to this earlier (holiday away on business). I was responsible for the spitfire model. Unfortunately the commitments of work and trying to have a social life didn't agree with continuing it. I hope to at some stage get some very detailed pictures on a later model spitfire. The model is based on a mkXIV and I have collected many pictures of the spit whilst I modelled it. These wouldn't be of much use in it's current state as all the geometry that's really missing is some ducts. Under wing and centre fuse. I never got as far as putting it into flightgear... but it's GPL'd from my standpoint. I think Jon had some data for the flight model. It is a hope of mine to have a Concorde model. However I find blender a bit backwards compared to what's available at work, and I'm not getting anymore free time than I was before. At work we have a flying spitfire and typhoon. I'm trying to get access to these so I can provide more detailed information on them e.g. photos etc. We also have the last production Concorde (lucky eh..). From my point of view I think the spitfire is a spectacular plane to watch, and I find the rumours about the design origin most interesting. I'll probably see some of you at the expo...thought it'd be a nice break from work. Chris ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Spitfire Hurricane manuals
On Mon, 08 Mar 2004 21:52:04 -0500, David Megginson [EMAIL PROTECTED] wrote: And psychological warfare. From what I've read, the German flight crews were much more frightened of the Spitfires (and British RADAR guidance for interceptions made it look like there were many more planes than the British actually had). Also, I'm not certain about this, but I believe that often the Spits would concentrate on engaging the fighters so that the Hurricanes could get at the bombers. Obviously, the Spits would rack up many fewer kills themselves that way, but I'm not sure how well the BoB would have gone if Britain hadn't been able to deploy a fighter well-matched with the ME-109. From what I've seen on TV and read, the hurricanes usually fared better against cannon equipped aircraft because they have a lot of fabric on their airframe. The cannon rounds would pass straight through many parts of the airframe causing a minimal amount of damage (minimal seems the wrong word to use!). Whereas the spitfires monocoque conventional structure took cannon rounds quite badly in comparison... There was a series of TV documentaries here recently called 'Spitfire Ace' which I thought was very good. I think you can buy the accompanying book from Amazon.co.uk. One of the quotes from a German pilot was with refernce to the 8 browning machine guns on the spitfire...it was something like 'if he gets you at the right distance with all 8 guns you will be caput!'. Whichever way you look at it they were brilliant, brave pilots on both sides. All the best, Matt. ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
RE: [Flightgear-devel] Spitfire Hurricane manuals
Lee Elliott On Monday 08 March 2004 13:21, David Megginson wrote: Vivian Meazza wrote: That could be useful. Could you let me have a copy? I'll send it via private e-mail. Also, for anyone interested in the Hurricane (the Spitfire's weaker and lesser known sibling, but also the plane that did the real bulk of the fighting in the Battle of Britain), here is a link to John Deakin's AvWeb articles on flying one for the Commemorative Airforce: http://www.avweb.com/news/columns/185674-1.html http://www.avweb.com/news/columns/185849-1.html All the best, David It's one of the aeronautical curiosities of WW2 that the Spitfire ended up as one of the most 'famous' a/c of that time. Certainly, it was an excellent a/c but as you say, it's contribution in the BoB, where it was only present in very small numbers, was far out-weighed by the Hurricane. Infact, some of the most notable exploits by Spitfires were in the field of PR, both high and low-level. In the later stages of WW2 the Typhoon Tempest became more significant (even though they were pressed into service while still in development - hence the early deserved reputation for structural reliability problems) as the role switched from defense to offense - the Spitfire wasn't suited for ground attack and it wasn't fast enough to deal with the V1s either. Don't anyone get me wrong - as I said, it's an excellent a/c, but it's fame is out of proportion to it's contribution. An example of the power of propaganda, perhaps... LeeE That's a bit harsh. The BoB was virtually the end of the Hurricane's career as a fighter, while the Spitfire was at its beginning. By repute it was delightful to fly, and forgiving in combat manoeuvre. Unlike the Typhoon and the Tempest the engine didn't stop or the tail fall off, although if you really went mad you could break the wings. It was in production in various guises throughout WWII although it had at least 3 new airframes and 2 engines. It remained competitive throughout as a fighter, but I would readily concede that the Typhoon and Tempest were better ground attack aircraft. Production numbers alone would ensure that it would be more famous than any other British type (Spitfire 20,340 Seafire 2,594). It was is also a delight to look at and to hear. I think you could make a case for it being the most famous (not the best) fighter aircraft of all time. And yes, the propaganda machine made best use of all this. Regards Vivian ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
RE: [Flightgear-devel] Spitfire Hurricane manuals
On Tue, 9 Mar 2004, Vivian Meazza wrote: delightful to fly, and forgiving in combat manoeuvre. Unlike the Typhoon and the Tempest the engine didn't stop or the tail fall off, although if you really went mad you could break the wings. It was in production in various I remember a tv programme a while ago where a particularly proud hurricane pilot said It was a lovely aircraft... and you'll not pull the wings of a hurricane!. I wouldn't say the spitfire was over hyped, but I do think the hurricane requires a bit more credit. -- Jon Stockill [EMAIL PROTECTED] ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
RE: [Flightgear-devel] Spitfire Hurricane manuals
On Tue, 2004-03-09 at 21:35, Jon Stockill wrote: On Tue, 9 Mar 2004, Vivian Meazza wrote: delightful to fly, and forgiving in combat manoeuvre. Unlike the Typhoon and the Tempest the engine didn't stop or the tail fall off, although if you really went mad you could break the wings. It was in production in various I remember a tv programme a while ago where a particularly proud hurricane pilot said It was a lovely aircraft... and you'll not pull the wings of a hurricane!. I wouldn't say the spitfire was over hyped, but I do think the hurricane requires a bit more credit. And just to remind us what the hype was all about http://www.alexisparkinn.com/photogallery/Videos/ohmygodSpitfire%20pass.wmv ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
RE: [Flightgear-devel] Spitfire Hurricane manuals
On Tue, 2004-03-09 at 02:35, Jon Stockill wrote: On Tue, 9 Mar 2004, Vivian Meazza wrote: delightful to fly, and forgiving in combat manoeuvre. Unlike the Typhoon and the Tempest the engine didn't stop or the tail fall off, although if you really went mad you could break the wings. It was in production in various I remember a tv programme a while ago where a particularly proud hurricane pilot said It was a lovely aircraft... and you'll not pull the wings of a hurricane!. Read a memoir someplace on the web sometime ago, this particular pilot managed to hit the wing of his Hurricane onto a tree and the wing stayed attached and he managed to make a safe landing. He said that if it had been a Spitfire the wing would have been ripped off. A lot of Hurricane pilots did carry burn scars from the plane, used to take damage well, but if it caught fire it would not take long before most of the airplane was engulfed, hence they wouls say, Hurricane burns. But then quite a few lived...The Bf109 had its fuel tank right below the cockpit, if that went up then pilot had really no chance of getting out. (Onn the subject of bailing out, after a certain speed the canopy would become impossible to open...Thats unimaginable). I wouldn't say the spitfire was over hyped, but I do think the hurricane requires a bit more credit. Yes, but so do the radar operators, the pilots of quite a few other types of planes that never get mentioned much, but still played a role (Defiant's, Wellington's, Blenheim's etc). I'd love to see the night fighting aspect explored too. I do recommend getting The Battle of Britain by Matthew Parker though, does not deal with statistics but also tells the lives of these pilots and the civilians who were on the ground. Matt ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Spitfire Hurricane manuals
On Tue, 9 Mar 2004 10:35:23 + (GMT), Jon Stockill [EMAIL PROTECTED] wrote: On Tue, 9 Mar 2004, Vivian Meazza wrote: delightful to fly, and forgiving in combat manoeuvre. Unlike the Typhoon and the Tempest the engine didn't stop or the tail fall off, although if you really went mad you could break the wings. It was in production in various I remember a tv programme a while ago where a particularly proud hurricane pilot said It was a lovely aircraft... and you'll not pull the wings of a hurricane!. I wouldn't say the spitfire was over hyped, but I do think the hurricane requires a bit more credit. The Hurricane was a good design, produced in a hurry (Ouch!), at the right time. But it was 'old technology', at heart (Ouch! Ouch!) it was a monoplane version of the Fury. But it shot down 80% of the RAFs victims in the BoB, mainly because it was vectored against the bombers. It couldn't really fight on even terms against the Me109 of that time, however, so the Spitfire was vectored against them wherever possible. The Spitfire, IMHO, earns its place for three reasons: a) It was the first fighter that held its own against the Lufwaffes equivalents. During the BoB it was the aircraft Dowding wanted, he switched squadrons to Spitfires as fast as he could. b) It was a superb 'pilots aeroplane', by all accounts a delight to fly. It therefore won the hearts of those who flew it. In combat this meant that pilots could direct less attention to their aircraft and more to fighting the enemy. c) It was an excellent basic design with lots of development potential. This allowed it to be given upgraded engines and armament which allowed it to keep pace with German fighter developments. Joe Smith (a much under appreciated man) took it from the Mk I to the Mk 24 - twice the power, a ton and a half heavier and 100 mph faster. Thus it remained in production from the begriming of the war to beyond its end. German Ace Adolf Galland to Goering, upon being asked what he needed to win the BoB: 'Spitfires'. Rick -- Help the Waterway Recovery Group to help restore the Uks canal network Make a donation to the 'Right Tool' Appeal http://www.wrg.org.uk/cgi-bin/fmaker.pl?appeal.htm ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Spitfire Hurricane manuals
Erik Hofman wrote: There was a developer who had an almost finished 3d model of the Spitfire once. I have no idea why it never showed up. I have a copy of his unfinished model, if anyone wants it. All the best, David ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
RE: [Flightgear-devel] Spitfire Hurricane manuals
David Megginson Sent: 08 March 2004 12:04 To: FlightGear developers discussions Subject: Re: [Flightgear-devel] Spitfire Hurricane manuals Erik Hofman wrote: There was a developer who had an almost finished 3d model of the Spitfire once. I have no idea why it never showed up. I have a copy of his unfinished model, if anyone wants it. That could be useful. Could you let me have a copy? Regards Vivian Meazza ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Spitfire Hurricane manuals
Vivian Meazza wrote: That could be useful. Could you let me have a copy? I'll send it via private e-mail. Also, for anyone interested in the Hurricane (the Spitfire's weaker and lesser known sibling, but also the plane that did the real bulk of the fighting in the Battle of Britain), here is a link to John Deakin's AvWeb articles on flying one for the Commemorative Airforce: http://www.avweb.com/news/columns/185674-1.html http://www.avweb.com/news/columns/185849-1.html All the best, David ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Spitfire Hurricane manuals
On Monday 08 March 2004 13:21, David Megginson wrote: Vivian Meazza wrote: That could be useful. Could you let me have a copy? I'll send it via private e-mail. Also, for anyone interested in the Hurricane (the Spitfire's weaker and lesser known sibling, but also the plane that did the real bulk of the fighting in the Battle of Britain), here is a link to John Deakin's AvWeb articles on flying one for the Commemorative Airforce: http://www.avweb.com/news/columns/185674-1.html http://www.avweb.com/news/columns/185849-1.html All the best, David It's one of the aeronautical curiosities of WW2 that the Spitfire ended up as one of the most 'famous' a/c of that time. Certainly, it was an excellent a/c but as you say, it's contribution in the BoB, where it was only present in very small numbers, was far out-weighed by the Hurricane. Infact, some of the most notable exploits by Spitfires were in the field of PR, both high and low-level. In the later stages of WW2 the Typhoon Tempest became more significant (even though they were pressed into service while still in development - hence the early deserved reputation for structural reliability problems) as the role switched from defense to offense - the Spitfire wasn't suited for ground attack and it wasn't fast enough to deal with the V1s either. Don't anyone get me wrong - as I said, it's an excellent a/c, but it's fame is out of proportion to it's contribution. An example of the power of propaganda, perhaps... LeeE ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Spitfire Hurricane manuals
Lee Elliott wrote: Certainly, it was an excellent a/c but as you say, it's contribution in the BoB, where it was only present in very small numbers, was far out-weighed by the Hurricane. I wouldn't say very small numbers -- I think that the ratio was about 2:1 for Hurricanes to Spitfires. Infact, some of the most notable exploits by Spitfires were in the field of PR, both high and low-level. And psychological warfare. From what I've read, the German flight crews were much more frightened of the Spitfires (and British RADAR guidance for interceptions made it look like there were many more planes than the British actually had). Also, I'm not certain about this, but I believe that often the Spits would concentrate on engaging the fighters so that the Hurricanes could get at the bombers. Obviously, the Spits would rack up many fewer kills themselves that way, but I'm not sure how well the BoB would have gone if Britain hadn't been able to deploy a fighter well-matched with the ME-109. All the best, David ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
RE: [Flightgear-devel] Spitfire Hurricane manuals
Erik Hofman wrote http://home.clara.net/wolverine/BOB/misc/Spit_Hurri_Manuals.zip Is this a hint ;-)? Vivian Meazza ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Spitfire Hurricane manuals
Vivian Meazza wrote: Erik Hofman wrote http://home.clara.net/wolverine/BOB/misc/Spit_Hurri_Manuals.zip Is this a hint ;-)? Yes. Erik ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Spitfire Hurricane manuals
Vivian Meazza wrote: Oddly enough, last weekend I found a book in my local bookstore on the Spitfire MkIIb, containing line drawings. I'll see if it's still there. If it is, I could do a model especially with the info in the pilot's notes. Is there a demand for a Spitfire IIB? There was a developer who had an almost finished 3d model of the Spitfire once. I have no idea why it never showed up. But yes, there is enough demand for _any_ Spitfire :_) Erik ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
RE: [Flightgear-devel] Spitfire Hurricane manuals
Erik Hofman wrote Vivian Meazza wrote: Oddly enough, last weekend I found a book in my local bookstore on the Spitfire MkIIb, containing line drawings. I'll see if it's still there. If it is, I could do a model especially with the info in the pilot's notes. Is there a demand for a Spitfire IIB? There was a developer who had an almost finished 3d model of the Spitfire once. I have no idea why it never showed up. But yes, there is enough demand for _any_ Spitfire :_) Erik Perhaps your discovery of the handbooks on the web will reawaken interest (neat one that!). I don't want to reinvent the wheel, so I'll see if the book is available, and then await developments before I embark on any serious work. Vivian. ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Spitfire Hurricane manuals
On Sunday 07 March 2004 10:40, Erik Hofman wrote: Vivian Meazza wrote: Erik Hofman wrote http://home.clara.net/wolverine/BOB/misc/Spit_Hurri_Manuals.zip Is this a hint ;-)? Yes. Erik LOL :))) I'm still re-working the A-10 atm - I've got a new 'bare-metal' finish .ac model but I'd still like to do a little more modelling work on it, as well as texture it properly, and then I need to re-work/re-build the B-52. And then there's the un-finished SR45 seaplane... After those, I was going to try to do some civil aircraft (actually, those high-aspect-ratio wing Hurel-Dubois a/c look quite interesting) LeeE ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
