Re: [Flightgear-devel] b1900d logo
syd wrote: I see from user screenshots that my idea of a transparent logo for the B1900d was a bad idea . Don't worry, the B1900D is still several users all-time-favourite ;-) I wouldn't care that much for the logo. I consider performance numbers to be of higher priority: You need to reach at least 130 kts in order to rotate (at sea level without flaps) but I'd expect such an aircraft to rotate at significant lower speed. Martin. -- Unix _IS_ user friendly - it's just selective about who its friends are ! -- ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] b1900d logo
On Tue, 20 Dec 2005 09:59:36 + (UTC) Martin Spott [EMAIL PROTECTED] wrote: syd wrote: I see from user screenshots that my idea of a transparent logo for the B1900d was a bad idea . Don't worry, the B1900D is still several users all-time-favourite ;-) I wouldn't care that much for the logo. I consider performance numbers to be of higher priority: You need to reach at least 130 kts in order to rotate (at sea level without flaps) but I'd expect such an aircraft to rotate at significant lower speed. As far as I know, rotation speed with no flaps and a service payload is about 105/110 kts. I could lift it at that speed some weeks ago, but some changes in the yasim code and/or in the b1900d.xml file caused a regression. -- Jean-Yves Lefort [EMAIL PROTECTED] http://lefort.be.eu.org/ pgpiM3fmHe8iD.pgp Description: PGP signature ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] b1900d logo
Jean-Yves Lefort wrote: As far as I know, rotation speed with no flaps and a service payload is about 105/110 kts. I could lift it at that speed some weeks ago, but some changes in the yasim code and/or in the b1900d.xml file caused a regression. Looking back through CVS, I think the big change was that the fuel load got doubled. If you cut the fuel down to about 2000 lbs total I think the aircraft will return. I made a small change to the config file so the aircraft lift/drag solution is computed at 80% fuel capacity rather than 20% fuel capacity ... this makes a huge difference in bringing the numbers back closer to what I'd expect. This is a WAG though ... we need to find a POH and start double checking stall speed and climb performance numbers to make sure we are in the right ball park here. I hate to guess too much. Curt. -- Curtis Olsonhttp://www.flightgear.org/~curt HumanFIRST Program http://www.humanfirst.umn.edu/ FlightGear Project http://www.flightgear.org Unique text:2f585eeea02e2c79d7b1d8c4963bae2d ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] b1900d logo
syd wrote: I see from user screenshots that my idea of a transparent logo for the B1900d was a bad idea . I always assume that if it works on my computer it must work on everyone else's:) BTW, my screenshot overhead the Tempelhof building was done on Win32, the logo looks correct on XOrg with the OpenSource ATI r200 driver without shadows. I just don't own a computer (I don't own any PeeCee at all ) that is powerful to display shadows, so I have to eomploy some Windows machine if I want to profit from all those nice features. Cheers, Martin. -- Unix _IS_ user friendly - it's just selective about who its friends are ! -- ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
[Flightgear-devel] b1900d logo
I see from user screenshots that my idea of a transparent logo for the B1900d was a bad idea . I always assume that if it works on my computer it must work on everyone else's:).Im learning ! Syd ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] B1900d: Fuel consumption when engine has stopped.
On Sun, 2005-11-06 at 09:12 -0800, Andy Ross wrote: George Patterson wrote: /engines/engine/fuel-flow-gph[0] is shown as -0.232562 (fluctuates rapidly) /engines/engine/running[0] is shown as false. Good catch. The really primitive stop support in the turbine engine model didn't set the fuel flow value. This is fixed, such as it is. Real start/stop support is on my list, and will probably be done with some Nasal such that it can be hacked on a per-engine basis. Andy Andy, (or whoever is maintaining the b1900d), I hate to do this to you, but I think I have spotted another bug to do with fuel and engines. When you run out of fuel the engines continue to run, despite /engine/engine/out-of-fuel[0]='true' and /consumables/fuel/total-fuel-gals|lbs|norm[0]='0.00' But the both engines are still running. I hope this is clearer.. George Patterson ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
RE: [Flightgear-devel] B1900d: Fuel consumption when engine hasstopped.
George Patterson writes Oops, that was a typo. I meant the engines continues to consume fuel even with engines stopped. Thats ok I thought it might be something simple but it did add a bit of humor to my day. Sorry about the confusion. Currently amending the getting started and installation guide. Thats great there is a lot of outdated stuff in there and I dont have the skill or knowledge or enthusasm to do anything about it. George Cheers Innis ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
RE: [Flightgear-devel] B1900d: Fuel consumption when engine hasstopped.
On Sun, 2005-11-06 at 20:00 +0800, Innis Cunningham wrote: George Patterson writes Oops, that was a typo. I meant the engines continues to consume fuel even with engines stopped. Thats ok I thought it might be something simple but it did add a bit of humor to my day. Sorry about the confusion. Currently amending the getting started and installation guide. Thats great there is a lot of outdated stuff in there and I dont have the skill or knowledge or enthusasm to do anything about it. LOL... Hence I have been working with Martin Splott to get the getstart manual into some sort of shape. Say does anyone know how you escape an @ symbol in LaTex. The rest of it is straight forward, if tedious. But I'm happy to be making a difference. George ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] B1900d: Fuel consumption when engine has stopped.
George Patterson wrote: /engines/engine/fuel-flow-gph[0] is shown as -0.232562 (fluctuates rapidly) /engines/engine/running[0] is shown as false. Good catch. The really primitive stop support in the turbine engine model didn't set the fuel flow value. This is fixed, such as it is. Real start/stop support is on my list, and will probably be done with some Nasal such that it can be hacked on a per-engine basis. Andy ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] B1900d: Fuel consumption when engine
George Patterson wrote: Say does anyone know how you escape an @ symbol in LaTex. I believe it's not necessary to escape the @, Martin. -- Unix _IS_ user friendly - it's just selective about who its friends are ! -- ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
[Flightgear-devel] B1900d: Fuel consumption when engine has stopped.
I have download the latest CVS data and compiled binaries for FlightGear and noticed that the fuel consumption for the b1900d continues even with the engines killed (cutoff). /engines/engine/fuel-flow-gph[0] is shown as -0.232562 (fluctuates rapidly) /engines/engine/running[0] is shown as false. The C172 doesn't behave properly. (It does not consume fuel unless the engine is running) George Patterson ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
RE: [Flightgear-devel] B1900d: Fuel consumption when engine has stopped.
Hi George George Patterson writes The C172 doesn't behave properly. (It does not consume fuel unless the engine is running) Hmm that would seem normal to me maybe I missed some thing. George Patterson Cheers Innis ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
RE: [Flightgear-devel] B1900d: Fuel consumption when engine has stopped.
On Sun, 2005-11-06 at 14:37 +0800, Innis Cunningham wrote: Hi George George Patterson writes The C172 doesn't behave properly. (It does not consume fuel unless the engine is running) Hmm that would seem normal to me maybe I missed some thing. Oops, that was a typo. I meant the engines continues to consume fuel even with engines stopped. Sorry about the confusion. Currently amending the getting started and installation guide. George ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
[Flightgear-devel] b1900d model still broken
The b1900d's ac3d file is still broken. It contains only four materials, but referenced are 0-4. There is no material 4! The new Blender importer doesn't like that, and it is right. I don't like it either. ;-) m. ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] B1900D
On Wednesday 19 Jan 2005 02:24, Curtis L. Olson wrote: Yasim has a magic solver that is sometimes sensitive to specific inputs. In the back of my head I imagine a little robot trying to climb to the highest point on the map by always going up ... but then coming to the top of a smaller hill and getting stuck. The solver tunes the lift and drag coefficients to make the aircraft hit the numbers you specify ... so if you provide engines that are too weak, you will end up with a super slick model which an incredibly efficient wing ... thus it can still hit the numbers but has really slow acceleration and climb. On the other end of the spectrum, if you provide too much power, you end up with a high drag, low lift model (so you don't blow past the provide performance numbers.) This will give you great ground acceleration and probably great climb, but will still top out at whatever numbers you specify. So once you have your basic YAsim model flying, you can tune things like rate of climb by adjusting actual engine output. You can tune roll/pitch rates by adjusting the size or effectiveness of the control surfaces. I'm not convinced you could get a YASim model close enough in every area to get FAA level 3 certification or higher, but you can get a really fine flying model in most regimes with a bit of tweaking and understanding (at least at a simple level) how various configuration options relate to each other. The other thing that confused me early on was how YAsim handles weight. I don't remember the rules well enough off the top of my head to summarize them here, but the solver solves at 80% fuel load I believe. This means that unless you are very careful with your fuel load and the weight the solver uses, you won't hit your performance numbers exactly ... those number only are for one particular aircraft weight. Once you figure out how to control the weight the solver uses and figure out how to configure the aircraft at that exact same weight, you do hit the performance numbers dead on. For someone like me with zero aeroengineering background, YAsim is a *really* fun tool to play around with. After a few hours with it, I almost feel like I understand it enough to build pretty plausible numbers. When it comes to stability derivatives and aero coefficients, I'm still pretty much as clueless as the day I was born. Curt. Thanks for the advice; the B1900D FDM is really coming on now. I've got her flying the 'envelope' and I'm managing to balance out the flight characteristics nicely. Something I noticed early on is that the mass needed distributing for things like Engine+Gearbox sets and Maingear etc as Yasim just evenly places the dry mass otherwise. I do agree that Yasim is great fun to work with - feels like I'm learning a lot. A bit more flight testing and then I will show what I have got and you can all 'shoot me down' ;-) Dave Martin Footnote: It appears that the B1900D props *do not* counter-rotate after all. ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] B1900D
Dave Martin wrote: Something I noticed early on is that the mass needed distributing for things like Engine+Gearbox sets and Maingear etc as Yasim just evenly places the dry mass otherwise. Yeah. Evenly placing the mass is a great way to get the overall mass distribution (the inertia tensor, for those who like the jargon) correct. But it's basically *never* going to produce an acceptable result if that's all you use. Most of the aircraft I did would tip backwards on their gear with the default masses. The idea is to place point masses at locations where you know the heavy stuff is (engines payload), and then let the solver come up with something plausible for wing fuselage masses. I believe it weights them according to their surface area. And, of course, there is always a final tuning stage where you move ballast around madly trying to get the aircraft to sit stably on its gear and still be able to lift the nose for takeoff. :) Andy ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
[Flightgear-devel] B1900D FDM (Test pilots req'd)
I've been working up the FDM for the b1900d and I have it flying quite nicely now. The numbers are no longer 'book' but rather ones that allow the aircraft to perform within the parameters of the FDM. Changes of note: The ailerons are more effective; with the 'infinite human strength' effect, full deflection (hence drag) is no-longer neccesary. The props are less 'massive' The props on the B1900D are actually very lightweight composite units. The reduced mass has alleviated the horrendous torque-induced roll. (The b1900d does not have counter-rotating props). Mass distribution is now in place for the nosewheel, avionics, engines, gearboxes and maingear. This reduces the pitch instability and the nose lifting at the start of the takeoff roll. Wings are now 'twisted' 3deg camber at the root to -1deg camber at the tips. The flat-rate is now 1000bhp/engine rather than the book figure to fit the POH characteristics rather than numbers. Flying it: Full power to take-off, 2-stages of flap, rotate at around 95kts, unstick 105kts. contine to rotate to prevent speed building too fast. Once the flaps are in and the gear is up, the aircraft should climb at a bit over 2000fpm at 160kts. Stalling: Clean occurs around 100kts with a fairly sharp wing-drop. Dirty (gear flaps) occurs 85kts or less sometimes with a *nasty* wing-drop if still heavily loaded - be careful! ;-) Landing: Once inside the flap-arc, 2 stages flap, 130kts gear-down, full flap, establish 120kts. Fly it all the way down like this and flare very gently while bringing the throttles back. (The nose will only be up a little compared to many other aircraft). To compare the landings with the real-thing, check http://www.flightlevel350.com for videos. Also note that the ASI doesn't appear to read dead-on at all speeds (or perhaps the HUD is on ground-speed??) Let me know what you think :-) FDM: http://www.cyfinity.com/fgfs/b1900d.xml - copy to your Aircraft/b1900d/ directory after backing up the original. Cheers! Dave Martin ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] B1900D FDM (Test pilots req'd)
On Thu, 20 Jan 2005 00:16:07 + Dave Martin wrote: Let me know what you think :-) FDM: http://www.cyfinity.com/fgfs/b1900d.xml - copy to your Aircraft/b1900d/ directory after backing up the original. Hi Dave. It appears to be a lot more stable (and as a note to Syd -- the model itself is gorgeous, especially the cockpit). But I can't check your numbers because I'm running into the transparent gauge problem that also afflicted the dhc2F. Where the gauges should be, I see right through to the runway. -c -- Chris Metzler [EMAIL PROTECTED] (remove snip-me. to email) As a child I understood how to give; I have forgotten this grace since I have become civilized. - Chief Luther Standing Bear pgpR1PKhvBJPN.pgp Description: PGP signature ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] B1900D FDM (Test pilots req'd)
Chris Metzler wrote: On Thu, 20 Jan 2005 00:16:07 + Dave Martin wrote: Let me know what you think :-) FDM: http://www.cyfinity.com/fgfs/b1900d.xml - copy to your Aircraft/b1900d/ directory after backing up the original. Hi Dave. It appears to be a lot more stable (and as a note to Syd -- the model itself is gorgeous, especially the cockpit). But I can't check your numbers because I'm running into the transparent gauge problem that also afflicted the dhc2F. Where the gauges should be, I see right through to the runway. The model was updated to work with FlightGear-0.9.8 and plib-1.8.4. Regards, Curt. -- Curtis Olsonhttp://www.flightgear.org/~curt HumanFIRST Program http://www.humanfirst.umn.edu/ FlightGear Project http://www.flightgear.org Unique text:2f585eeea02e2c79d7b1d8c4963bae2d ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] B1900D FDM (Test pilots req'd)
On Wed, 19 Jan 2005 21:34:24 -0600 Curtis L. Olson wrote: The model was updated to work with FlightGear-0.9.8 and plib-1.8.4. Sigh . . .I should really subscribe to the CVS log mailing list. I thought I was current; but I wasn't 11 hours current. Thanks for the tip. -c -- Chris Metzler [EMAIL PROTECTED] (remove snip-me. to email) As a child I understood how to give; I have forgotten this grace since I have become civilized. - Chief Luther Standing Bear pgpyhdtUuI3Tk.pgp Description: PGP signature ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
[Flightgear-devel] b1900d FDM
Is anyone currently working on the b1900d FDM? The reason I ask is that while the model is gorgeous, the FDM is relatively broken. I've tried fixing the FDM before a couple of months ago but I didn't get anything acceptable. The aircraft accelerates at a hell of a rate on the ground but wont unstick until about 160kts with flap and when it does, the torque effect requires full right aileron to counteract until the airspeed reaches 200kts. (which takes a matter of seconds). Also, if you fight the aircraft level and then apply full-flap, cut the throttles and hold your altitude to the stall, you find that the stall occurs at 120kts and immediately causes a vicious spin. For the Torque, don't the b1900d's have counter-rotating props? As for the FDM's aerodynamics, I've yet to work out exactly what is wrong (the numbers look right but the result is rather like a dragster without wings). Any thoughts? Dave Martin ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] b1900d FDM
On Tue, 18 Jan 2005 16:47:04 + Dave Martin [EMAIL PROTECTED] wrote: Is anyone currently working on the b1900d FDM? The reason I ask is that while the model is gorgeous, the FDM is relatively broken. I know there is a YASim model, and I've wanted to work on a JSBSim model for some time, but as the coordinator for JSBSim, editor for the Houston AIAA chapter newsletter, trying to get somewhere on the 1st quarter JSBSim newsletter, being in the middle of a job transition, and being a father of four ... it's a near miracle that I've almost completed the code transition to support JSBSim config file v2.0. :-) If you are interested in doing a JSBSim version of the B1900, I can probably put together a data packet to support that work. Jon ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] b1900d FDM
Dave Martin wrote: Is anyone currently working on the b1900d FDM? The reason I ask is that while the model is gorgeous, the FDM is relatively broken. I've tried fixing the FDM before a couple of months ago but I didn't get anything acceptable. The aircraft accelerates at a hell of a rate on the ground but wont unstick until about 160kts with flap and when it does, the torque effect requires full right aileron to counteract until the airspeed reaches 200kts. (which takes a matter of seconds). Also, if you fight the aircraft level and then apply full-flap, cut the throttles and hold your altitude to the stall, you find that the stall occurs at 120kts and immediately causes a vicious spin. For the Torque, don't the b1900d's have counter-rotating props? As for the FDM's aerodynamics, I've yet to work out exactly what is wrong (the numbers look right but the result is rather like a dragster without wings). My guess is the approach speed is too high ... you have to be careful because as the file is setup, approach speed is 105 at 13 deg aoa, but full stall is 14 deg aoa. This is saying the aircraft approaches at 105 kts just above the edge of a stall. Add some additional weight (which is often the case) and this could put you right up near 120 for a stall point. I think that either the approach aoa should be dropped significantly, or the speed you can just barely fly without stalling needs to be decreased. Just a guess, but I bet you could fly it down into the range of 80-85 kts full flaps without stalling it (given a moderate load and reasonable temp conditions.) I don't have a b1900 POH, but I wouldn't be surprised if I ended up with one by the end of the year ... I'd agree that the propellors should probably be made counter rotating by negating the moment on one of the sides. The Beech99 is a similar airplane which actually flies pretty close to the POH numbers so you could probably yank data out of there and at least make the 1900 a bit more plausible. Yes, the 3d model and 3d cockpit is gorgeous. :-) Regards, Curt. -- Curtis Olsonhttp://www.flightgear.org/~curt HumanFIRST Program http://www.humanfirst.umn.edu/ FlightGear Project http://www.flightgear.org Unique text:2f585eeea02e2c79d7b1d8c4963bae2d ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
[Flightgear-devel] B1900D
Hi all ... I see someone else is having problems with the B1900D. It was my first attempt at a yasim aircraft ... and I still cant get it to fly right ! I dont know about the counter rotating props ... it was a LOT of guess work. So if someone can find a cure for it or give me specs , I'll be happy to attempt to fix it . ( It is a long way from being finished). I did read somewhere that it had a wing incidence of about +3.5 at the root and -1 at the tip , but it crashes the program every time I try to implement it . Im currently fixing the panel for plib 1.8.4 , should be able to send an update tonight. Im afraid Ive tweaked the FDm to the point where it crashes FGFS AND FGRUN :) ... so I'll leave that out .Cheers Syd ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] B1900D
On Wednesday 19 Jan 2005 01:14, Syd wrote: Hi all ... I see someone else is having problems with the B1900D. It was my first attempt at a yasim aircraft ... and I still cant get it to fly right ! I dont know about the counter rotating props ... it was a LOT of guess work. So if someone can find a cure for it or give me specs , I'll be happy to attempt to fix it . ( It is a long way from being finished). I did read somewhere that it had a wing incidence of about +3.5 at the root and -1 at the tip , but it crashes the program every time I try to implement it . Im currently fixing the panel for plib 1.8.4 , should be able to send an update tonight. Im afraid Ive tweaked the FDm to the point where it crashes FGFS AND FGRUN :) ... so I'll leave that out .Cheers Syd ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d Lovely model! Well, so far, I've counter-rotated the props for now till I can find out if they do in real life. I've got the thing flying reasonably and the stall normalised at about 80-85 dirty / 100ish clean. I've already experienced what you mention with the incidence at the tips (the twist of the wing). I'm trying to work out if I can make an average between the two that wont make Yasim throw the toys out of the pram. I've also managed to reduce the 'dragster' runway performance a bit but it needs more work to match up things like rate-of-climb etc to the real figures. Cheers Dave Martin ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] B1900D
Dave Martin wrote: Lovely model! Well, so far, I've counter-rotated the props for now till I can find out if they do in real life. I've got the thing flying reasonably and the stall normalised at about 80-85 dirty / 100ish clean. I've already experienced what you mention with the incidence at the tips (the twist of the wing). I'm trying to work out if I can make an average between the two that wont make Yasim throw the toys out of the pram. I've also managed to reduce the 'dragster' runway performance a bit but it needs more work to match up things like rate-of-climb etc to the real figures. Yasim has a magic solver that is sometimes sensitive to specific inputs. In the back of my head I imagine a little robot trying to climb to the highest point on the map by always going up ... but then coming to the top of a smaller hill and getting stuck. The solver tunes the lift and drag coefficients to make the aircraft hit the numbers you specify ... so if you provide engines that are too weak, you will end up with a super slick model which an incredibly efficient wing ... thus it can still hit the numbers but has really slow acceleration and climb. On the other end of the spectrum, if you provide too much power, you end up with a high drag, low lift model (so you don't blow past the provide performance numbers.) This will give you great ground acceleration and probably great climb, but will still top out at whatever numbers you specify. So once you have your basic YAsim model flying, you can tune things like rate of climb by adjusting actual engine output. You can tune roll/pitch rates by adjusting the size or effectiveness of the control surfaces. I'm not convinced you could get a YASim model close enough in every area to get FAA level 3 certification or higher, but you can get a really fine flying model in most regimes with a bit of tweaking and understanding (at least at a simple level) how various configuration options relate to each other. The other thing that confused me early on was how YAsim handles weight. I don't remember the rules well enough off the top of my head to summarize them here, but the solver solves at 80% fuel load I believe. This means that unless you are very careful with your fuel load and the weight the solver uses, you won't hit your performance numbers exactly ... those number only are for one particular aircraft weight. Once you figure out how to control the weight the solver uses and figure out how to configure the aircraft at that exact same weight, you do hit the performance numbers dead on. For someone like me with zero aeroengineering background, YAsim is a *really* fun tool to play around with. After a few hours with it, I almost feel like I understand it enough to build pretty plausible numbers. When it comes to stability derivatives and aero coefficients, I'm still pretty much as clueless as the day I was born. Curt. -- Curtis Olsonhttp://www.flightgear.org/~curt HumanFIRST Program http://www.humanfirst.umn.edu/ FlightGear Project http://www.flightgear.org Unique text:2f585eeea02e2c79d7b1d8c4963bae2d ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
