Re: KR> Angle of attack
Interesting question about the "outside wing" The most common use where I've seem AOA demonstrated is on final. We're on 2000' grass. Landing to the west is over a road and the state of Oregon wants pilots to cross that at 20'+. So the 2000' becomes shorter. Approaching final with "reserve lift" or above the critical AOA can permit steeper glide path without increasing speed. Sort of like hearing the stall horn just before touchdown. My IFR instructor made me realize the C172 fresh air vents have a fluttering sound that comes on about 3 - 5 mph before the first stall warning horn. I'm hoping to get the same preliminary input from the AOA. Or maybe I'm just a gadget monkey! John Bouyea N5391M/ KR2 OR81/ Hillsboro, OR 2015 KR@MMV Gathering CoHost -Original Message- From: KRnet [mailto:krnet-boun...@list.krnet.org] On Behalf Of Tony King via KRnet ... Does an AOA probe fitted to one wing detect an impending stall situation equally for both wings? Or should it be fitted to the left wing on the basis that the turns in the circuit are usually left turns and it's the inside wing that's more likely to stall? ___ Search the KRnet Archives at https://www.mail-archive.com/krnet@list.krnet.org/. Please see LIST RULES and KRnet info at http://www.krnet.org/info.html. see http://list.krnet.org/mailman/listinfo/krnet_list.krnet.org to change options. To UNsubscribe from KRnet, send a message to krnet-le...@list.krnet.org
Re: KR> Angle of attack
OK, now I see what your getting at. I always carry more speed than I should while turning in the pattern, Trying to slow this thing down is like trying to catch a greased pig at the State Fair. Mike Sylvester kr2s builder Birmingham,AL. Cell no.205-966-3854 From: KRnet on behalf of Tony King via KRnet Sent: Monday, February 12, 2018 6:25 PM To: KRnet Cc: Tony King Subject: Re: KR> Angle of attack 'Knowing. During low speed manoeuvring (e.g. turning onto final) you might be a lot closer to the stall than you realise, Cheers, Tony ___ Search the KRnet Archives at https://www.mail-archive.com/krnet@list.krnet.org/. krnet - The Mail Archive<https://www.mail-archive.com/krnet@list.krnet.org/> www.mail-archive.com Messages by Thread Re: KR> finally a flight Brant Hollensbe via KRnet; KR> Mt. Vernon Motels Mike Stirewalt via KRnet. KR> progress Flesner via KRnet Please see LIST RULES and KRnet info at http://www.krnet.org/info.html. KRNet "Basic" Instructions<http://www.krnet.org/info.html> www.krnet.org Join the KRnet email list by sending an email to krnet-ow...@list.krnet.org. Please include your name, address, phone number, and a sentence or two on why you'd like ... see http://list.krnet.org/mailman/listinfo/krnet_list.krnet.org to change options. KRnet Info Page - list.krnet.org<http://list.krnet.org/mailman/listinfo/krnet_list.krnet.org> list.krnet.org KRnet is a mailinglist devoted to construction and flying the KR series of homebuilt experimental aircraft. To see the collection of prior postings to the list ... To UNsubscribe from KRnet, send a message to krnet-le...@list.krnet.org ___ Search the KRnet Archives at https://www.mail-archive.com/krnet@list.krnet.org/. Please see LIST RULES and KRnet info at http://www.krnet.org/info.html. see http://list.krnet.org/mailman/listinfo/krnet_list.krnet.org to change options. To UNsubscribe from KRnet, send a message to krnet-le...@list.krnet.org
Re: KR> Angle of attack
A friend built one exactly as drawn in the Airsoob "white paper" and mounted it on the left wing of his BD-4 for the very reason you describe. He figured slow turns in the pattern were when he most needed to know what was going re: AoA. Chris On 2/12/2018 5:25 PM, Tony King via KRnet wrote: Here's a question though. The AOA probe is fitted to one or other wing. But an inadvertent spin such as I've just described is caused by one wing stalling while the other is still flying. Does an AOA probe fitted to one wing detect an impending stall situation equally for both wings? Or should it be fitted to the left wing on the basis that the turns in the circuit are usually left turns and it's the inside wing that's more likely to stall? Cheers, Tony ___ ___ Search the KRnet Archives at https://www.mail-archive.com/krnet@list.krnet.org/. Please see LIST RULES and KRnet info at http://www.krnet.org/info.html. see http://list.krnet.org/mailman/listinfo/krnet_list.krnet.org to change options. To UNsubscribe from KRnet, send a message to krnet-le...@list.krnet.org
Re: KR> Angle of attack
'Knowing' that their aircraft stalls at a certain speed has killed many pilots. In fact it's possible to stall an aircraft at any speed because stall is about angle of attack, not airspeed. The quoted stall speed for an aircraft is usually calculated when the aircraft is straight and level and if you're lucky at max weight. Bank the aircraft and the stall speed goes up. During low speed manoeuvring (e.g. turning onto final) you might be a lot closer to the stall than you realise, even though you're well above the quoted stall speed. Get a little bit slower than usual and bank a little harder than usual (e.g. because you overshot the centreline) and you might find yourself spiralling into the ground. Here's a question though. The AOA probe is fitted to one or other wing. But an inadvertent spin such as I've just described is caused by one wing stalling while the other is still flying. Does an AOA probe fitted to one wing detect an impending stall situation equally for both wings? Or should it be fitted to the left wing on the basis that the turns in the circuit are usually left turns and it's the inside wing that's more likely to stall? Cheers, Tony ___ Search the KRnet Archives at https://www.mail-archive.com/krnet@list.krnet.org/. Please see LIST RULES and KRnet info at http://www.krnet.org/info.html. see http://list.krnet.org/mailman/listinfo/krnet_list.krnet.org to change options. To UNsubscribe from KRnet, send a message to krnet-le...@list.krnet.org
KR> Angle of attack
I have a friend that has one in his STOL airplane and absolutely loves it. So much so that he can't believe that I fly without one. I just don't see the point, If you know where stall is in MPH isn't that the same? Mike Sylvester kr2s builder Birmingham,AL. Cell no.205-966-3854 ___ Search the KRnet Archives at https://www.mail-archive.com/krnet@list.krnet.org/. Please see LIST RULES and KRnet info at http://www.krnet.org/info.html. see http://list.krnet.org/mailman/listinfo/krnet_list.krnet.org to change options. To UNsubscribe from KRnet, send a message to krnet-le...@list.krnet.org
KR> Angle of Attack sys
Here is how I made mine. http://kr2spacemodulator.blogspot.com.au/2008/06/kr-2ss-pitotstaticaoa-probe .html Paul, Brisbane, Australia. ++ At 11:53 AM 2/24/2016, you wrote: >Has anyone installed an AOA warning system in their KR-2S? I'm looking >for suggestions as to pressure port locations that anyone has used for >their installation.
KR> Angle of Attack sys
Thanks Larry. I have been reading up on the Skyview sys which I have for my panel. I wasn't aware of all the capabilities of the system. You mentioned that you had helped install a Skyview sys w/ AoA in a friend's RV-10. I haven't completely digested all the features of the Skyview sys. Does the AoA require an additional component or is it a built-in feature of the system? If it is part of the system, I may just purchase the static/AoA probe and sell the Advanced Flight AoA package. Decisions, decisions. Pete > Date: Wed, 24 Feb 2016 22:29:00 -0600 > To: pkengr at hotmail.com > From: flesner at frontier.com > Subject: RE: KR> Angle of Attack sys > > At 08:35 PM 2/24/2016, you wrote: > >I misspoke. The unit I have is the Sport not the Pro version where > >you have to install pressure ports in the bottom and top of the wing > >somewhere between 15 to 40% of the wing chord. > > > Pete, > > Looking at the 125 page document ( > http://www.advanced-flight-systems.com/Support/AOAsupport/aoasupport.html > ), they seem to imply that it is not that critical as long as you > follow the "don't place near tip, propeller arc, etc., as long as > the top and bottom are located at the same % of chord and offset by 2 > to 4 inches ( I think that's what I read). > > A mid wing location would have a chord of approx 42 inches. 25% > would be 10.5 inches and I think that would be just behind the > spar. I'm guessing at these measurements but that's where I think > I'd locate them. A small access panel for installation could be cut > BEHIND each port. Check the site in blue below. May be more info there. > > Larry > > > === > page 40 > > There are some places where pressure ports should > not be located on the wing such as in line with the > propeller wash, too close to the wing tip, and in areas > difficult to access. Generally 15% to 40% chord and > forward of the ailerons will work well. The upper and > lower ports should be located at the same % chord but > offset by 2" to 4" spanwise. > A. Pick the pressure port locations. For the best wing > port locations, check the Appendix I or better yet, > our web site at > www.angle-of-attack.com > for the > most recent information. >
KR> Angle of Attack sys
Larry I misspoke. The unit I have is the Sport not the Pro version where you have to install pressure ports in the bottom and top of the wing somewhere between 15 to 40% of the wing chord. My question was where along the wing, outside the prop wash area, is the best place. Is there a problem with being to close to the wingtip or a fuel cap, does surface with rivets pose an issue? Those are the questions I have. Pete > Date: Wed, 24 Feb 2016 15:21:40 -0600 > To: krnet at list.krnet.org > Subject: KR> Angle of Attack sys > From: krnet at list.krnet.org > CC: flesner at frontier.com > > At 11:53 AM 2/24/2016, you wrote: > >Has anyone installed an AOA warning system in their KR-2S? I'm > >looking for suggestions as to pressure port locations that anyone > >has used for their installation. > ++ > > Pete, > > I looked at the unit you have on line. Both pressure ports on > located on the single pitot assembly. You simply have to get the > pitot assembly located on the wing to be properly aligned for cruise > or as directed in the mounting instructions. As the angle of attack > increases at slower speeds, the difference in pressure between the > two fixed ports gives you a read on the panel. The pitot assembly > looks exactly like the one installed on a friends RV10. Once > installed, it was calibrated in flight with a simple procedure of > doing a 5 degree nose up and down from level flight and then doing a > stall. Yours will have its own specific instructions. If you don't > have the procedure for your assembly, contact the manufacturer. > > Larry Flesner > > > ___ > Search the KRnet Archives at http://tugantek.com/archmailv2-kr/search. > To UNsubscribe from KRnet, send a message to KRnet-leave at list.krnet.org > please see other KRnet info at http://www.krnet.org/info.html > see http://list.krnet.org/mailman/listinfo/krnet_list.krnet.org to change > options
KR> Angle of Attack sys
You want the probs in clean air as possible. However you will calibrate it to your airplane and that will take out all the variables.? Paul ViskBellevill Il.?618 406 4705 however Sent from my Sprint Samsung Galaxy S? 6. Original message From: Pete Klapp via KRnet Date: 2/24/2016 8:35 PM (GMT-06:00) To: krnet at list.krnet.org Cc: Pete Klapp Subject: Re: KR> Angle of Attack sys Larry I misspoke. The unit I have is the Sport not the Pro version where you have to install pressure ports in the bottom and top of the wing somewhere between 15 to 40% of the wing chord. My question was where along the wing, outside the prop wash area, is the best place. Is there a problem? with being to close to the wingtip or a fuel cap, does surface? with rivets pose an issue? Those are the questions I have. Pete > Date: Wed, 24 Feb 2016 15:21:40 -0600 > To: krnet at list.krnet.org > Subject: KR> Angle of Attack sys > From: krnet at list.krnet.org > CC: flesner at frontier.com > > At 11:53 AM 2/24/2016, you wrote: > >Has anyone installed an AOA warning system in their KR-2S? I'm > >looking for suggestions as to pressure port locations that anyone > >has used for their installation. > ++ > > Pete, > > I looked at the unit you have on line.? Both pressure ports on > located on the single pitot assembly.? You simply have to get the > pitot assembly located on the wing to be properly aligned for cruise > or as directed in the mounting instructions.? As the angle of attack > increases at slower speeds, the difference in pressure between the > two fixed ports gives you a read on the panel.? The pitot assembly > looks exactly like the one installed on a friends RV10.? Once > installed, it was calibrated in flight with a simple procedure of > doing a 5 degree nose up and down from level flight and then doing a > stall.? Yours will have its own specific instructions. If you don't > have the procedure for your assembly, contact the manufacturer. > > Larry Flesner > > > ___ > Search the KRnet Archives at http://tugantek.com/archmailv2-kr/search. > To UNsubscribe from KRnet, send a message to KRnet-leave at list.krnet.org > please see other KRnet info at http://www.krnet.org/info.html > see http://list.krnet.org/mailman/listinfo/krnet_list.krnet.org to change > options ?? ? ___ Search the KRnet Archives at http://tugantek.com/archmailv2-kr/search. To UNsubscribe from KRnet, send a message to KRnet-leave at list.krnet.org please see other KRnet info at http://www.krnet.org/info.html see http://list.krnet.org/mailman/listinfo/krnet_list.krnet.org to change options
KR> Angle of Attack sys
At 11:53 AM 2/24/2016, you wrote: >Has anyone installed an AOA warning system in their KR-2S? I'm >looking for suggestions as to pressure port locations that anyone >has used for their installation. ++ Pete, I looked at the unit you have on line. Both pressure ports on located on the single pitot assembly. You simply have to get the pitot assembly located on the wing to be properly aligned for cruise or as directed in the mounting instructions. As the angle of attack increases at slower speeds, the difference in pressure between the two fixed ports gives you a read on the panel. The pitot assembly looks exactly like the one installed on a friends RV10. Once installed, it was calibrated in flight with a simple procedure of doing a 5 degree nose up and down from level flight and then doing a stall. Yours will have its own specific instructions. If you don't have the procedure for your assembly, contact the manufacturer. Larry Flesner
KR> Angle of attack
At 11:11 AM 2/20/2014, you wrote: >The slower the better in an emergency. On the mains is not as slow >as three point. I know this is going to bring up a big debate. But >as Mark says when you need to get stop fast there's only one way to do it. +++ Nothing really here to debate. In an emergency, the slower the better and I'd probably even touch tail wheel first in an off airport landing in unfriendly terrain. But, in a non-emergency situation, I feel I have better control and better visibility doing a tail low wheel landing. We're not talking a big difference in speed here, maybe 5 mph or less at actual touchdown. If I were flying a Cessna 150, I wouldn't be dragging it in with power and full flaps, making a short or soft field landing on every approach, just in case I need to make that type of approach someday. In my KR, the three point attitude blocks all forward vision so I can't even judge my height above the runway. I get the feeling I'm just along for the ride the last few seconds before touchdown. In a tail low wheel landing I have visibility over the nose until I'm under flying speed and can quickly recognize and stop any drift in a crosswind. It really is no different than the approach and touchdown of a tri-gear airplane. The only difference is my tail goes down as I slow and their's goes up as they slow. If the three point touchdown were the only acceptable way to land a KR, the tri-gear pilots would be dragging their tails on touchdown. Just a thought. Each aircraft has it's own handling requirements and should be flown accordingly, given the variables of each flight. Personally, I can't recall ever seeing DC3's, B17's, and the like making three point landings. Go with what makes you feel good. Larry Flesner
KR> Angle of attack
At 10:26 AM 2/20/2014, you wrote: >Larry >has an O-200 in his plane and hasn't had the pleasure of very many >engine-out landings (none, I'm guessing), unlike me, and I hope he never >does. +++ Mark is correct. That's one of the reasons I went with the 0-200. It too may bite me someday but I'm guessing the odds are more in my favor. I do practice "engine at idle" landings but I'm guessing that is not the same as a wind milling or stopped prop by a good percentage. It does give me an idea of what a high sink rate looks like in my heavy KR with stock wings. Practice makes perfect and, in so doing, Mark has saved his bacon several times. Good luck is often the result of practice and planning and Mark does both. :-) Everyone's flying environment is a bit different. Fly within your comfort zone.. Larry Flesner
KR> Angle of attack
I probably have 2000 hours in tailwheel airplanes. Almost 800in a KR 2. I also own a bellanca cruiseair tailwheel have a lot of time in a Luscombe ,T craft and a couple of other tailwheel airplanes. I could probably count how many main wheel landings I have done on both hands. For those that do not know me I've been down six times in a KR 2 everyone of those I did a three point Landing to get it shut down. I can guarantee you if I'd had to land on the mains on two of those that I would not have gotten stopped in the time that I had. Everybody has their own ideas of how to land an airplane. The slower the better in an emergency. On the mains is not as slow as three point. I know this is going to bring up a big debate. But as Mark says when you need to get stop fast there's only one way to do it. Sent from my iPhone > On Feb 20, 2014, at 8:56 AM, Larry&Sallie Flesner > wrote: > > At 06:35 AM 2/20/2014, you wrote: >> Doran Jaffas wrote: >> >> >In the three point Landing configuration is anyone have any knowledge of >> the optimum angle of attack for the KR two standard? >> > > > I think Mark was in the ball park with the 12 degrees number. I recall mine > being right at 12 degrees. > > That brings up another point. The three point landing. Many call it a "full > stall" landing. Be advised, it is NOT a full stall landing. I suspect there > is not a tailwheel aircraft flying that has the wing at a stalled angle in > the three point attitude. If the pilot can touch the tailwheel before the > mains (as I did on my first landing) then the wing is not stalled. That > means that if you touch down in the three point attitude, the wing is still > flying and any slight gust of head wind can and probably will lift one or > both wings. > > My preferred landing technique is to land on the mains with the tail slightly > low with a slight forward stick at touchdown to decrease the angle of attack > and plant the mains firmly on the ground. I hold the tail up until the wing > is below flying speed, allow the tail to drop, at which point I can use > maximum braking. That's pretty much how Jim Faughn described it in his " how > to land a KR" article available on the net somewhere. > > Mark's home airport runway is 2700 feet in length. On the one occasion I had > to visit him I was at taxi speed approximately half way down the runway. I > must confess that the direction I was landing, the runway has a slight > upgrade. Never the less, at my home airport, I can be down and do a 180 in > 1500 feet, no wind, with mild braking, doing a wheel landing. > > Everyone has a technique they are comfortable with. To me, the tail low > wheel landing offers me the greatest control in most all wind conditions and > makes for nice soft touchdowns. Go with what makes you feel good. :-) > > Larry Flesner > > > > > ___ > Search the KRnet Archives at http://tugantek.com/archmailv2-kr/search. > To UNsubscribe from KRnet, send a message to KRnet-leave at list.krnet.org > please see other KRnet info at http://www.krnet.org/info.html > see http://list.krnet.org/mailman/listinfo/krnet_list.krnet.org to change > options
KR> Angle of attack
The three point picture you see sitting on the ground. Watch your speed or you will float down the runway, Virg On 2/20/2014 3:44 AM, Doran Jaffas wrote: > in the three point Landing configuration is anyone have any knowledge > of the optimum angle of attack for the KR two standard? >Doran > N186RC > ___ > Search the KRnet Archives at http://tugantek.com/archmailv2-kr/search. > To UNsubscribe from KRnet, send a message to KRnet-leave at list.krnet.org > please see other KRnet info at http://www.krnet.org/info.html > see http://list.krnet.org/mailman/listinfo/krnet_list.krnet.org to change > options >
KR> Angle of attack
Larry Flesner wrote: >>Mark's home airport runway is 2700 feet in length. On the one occasion I had to visit him I was at taxi speed approximately half way down the runway. I must confess that the direction I was landing, the runway has a slight upgrade. Never the less, at my home airport, I can be down and do a 180 in 1500 feet, no wind, with mild braking, doing a wheel landing.<< OK, here's the rest of my logic. I started landing this way when I first started flying out of M38, and after a while, I too can pull off a landing with no braking at all, although that's rare...there's usually some braking required. The driving thing behind all my landings is that they are simulated emergency landings. I want every landing to be as slow as possible, with minimal energy left in the plane, as well as my body. Larry has an O-200 in his plane and hasn't had the pleasure of very many engine-out landings (none, I'm guessing), unlike me, and I hope he never does. When I put mine down in a small terraced hay field with a broken crank two years ago, I'm glad it was a no-brainer to put it on the ground "as usual" without even thinking (or experimenting) at a time when it really mattered. I don't think a wheel landing would have been very satisfying for me. My mileage has definitely varied, so apparently it's a matter of opinion. Do what makes you comfortable... Mark Langford, Harvest, AL ML at N56ML.com www.N56ML.com
KR> Angle of attack
At 06:35 AM 2/20/2014, you wrote: >Doran Jaffas wrote: > > >In the three point Landing configuration is anyone have any knowledge of >the optimum angle of attack for the KR two standard? > I think Mark was in the ball park with the 12 degrees number. I recall mine being right at 12 degrees. That brings up another point. The three point landing. Many call it a "full stall" landing. Be advised, it is NOT a full stall landing. I suspect there is not a tailwheel aircraft flying that has the wing at a stalled angle in the three point attitude. If the pilot can touch the tailwheel before the mains (as I did on my first landing) then the wing is not stalled. That means that if you touch down in the three point attitude, the wing is still flying and any slight gust of head wind can and probably will lift one or both wings. My preferred landing technique is to land on the mains with the tail slightly low with a slight forward stick at touchdown to decrease the angle of attack and plant the mains firmly on the ground. I hold the tail up until the wing is below flying speed, allow the tail to drop, at which point I can use maximum braking. That's pretty much how Jim Faughn described it in his " how to land a KR" article available on the net somewhere. Mark's home airport runway is 2700 feet in length. On the one occasion I had to visit him I was at taxi speed approximately half way down the runway. I must confess that the direction I was landing, the runway has a slight upgrade. Never the less, at my home airport, I can be down and do a 180 in 1500 feet, no wind, with mild braking, doing a wheel landing. Everyone has a technique they are comfortable with. To me, the tail low wheel landing offers me the greatest control in most all wind conditions and makes for nice soft touchdowns. Go with what makes you feel good. :-) Larry Flesner
KR> Angle of attack
Doran Jaffas wrote: >In the three point Landing configuration is anyone have any knowledge of the optimum angle of attack for the KR two standard? That depends...on how much runway you have, where you're talking about in the landing process, and how hard you want to whack the runway with the tailwheel, among other things! If you mean at touchdown, I've perfected a landing in N56ML where about a 2/3 of the time the tailwheel hits after the mains, and the other 1/3 of the time it hits before the mains, which I think is about as quick and safe as you can land one, because it's done flying at that point. I'm sure there are other opinions though, but this is how I "three-point" one, with power at idle, so it's losing altitude, and the timing has to be just right. That's the only way I land it, as a rule, due to my short runway length. The airfoil is pretty much stalled at 16 degrees (see plot at http://www.krnet.org/as504x/ ), so it's somewhat less. If I remember correctly, N56ML's longeron is something like 12 degrees sitting on it's gear. Mark Langford, Harvest, AL ML at N56ML.com www.N56ML.com
KR> Angle of attack
in the three point Landing configuration is anyone have any knowledge of the optimum angle of attack for the KR two standard? Doran N186RC
KR> Angle of attack
Netters Lets make this really simple: Angle of attack is the angle created between the chord line and the relative wind. Period. The chord line is an imaginary line that we create for discussion of the characteristics of a wing and is from the center of the leading edge to the center of the trailing edge if viewed from the end of the wing tip looking towards the fuselage. The relative wind is NOT the direction of the wind blowing at the aircraft at a given time, nor is it the direction of travel of the aircraft. It is the direction of airflow just before it begins passing over the wing at the leading edge. It was correctly stated earlier that the aircraft stalls at the same angle of attack for a given wing no matter what the flight attitude, and that is true. This angle is known as the critical angle of attack, and this does not change for a particular wing. If we are in cruise climb, the angle of attack is small because we are using surplus power to provide more thrust thean we need for level flight and we have pointed the nose up in order for the wing to make more lift than is necessary for level flight, which is increasing the angle of attack. What must be understood is that when we test our KRs for the stall speed from straight & level flight, whether power on or off, we are not pulling any Gs to speak of, barely over 1G if that. However, lets say we are performing a steep turn and allow the angle of BANK to roll on over to 60 degrees. All aircraft regardless of make will experience 2Gs. This increases the wing loading AND RAISES the stall speed of the aircraft because the effective weight that the wing must now keep in flight is twice what it was in level flight. That changes the critical angle of attack for that wing loading, referred to as an accelerated maneuvering stall. Finding the correct location for a stall warning device is not just picking an arbitrary point on the wing, and as Dan stated, bad information is worse than no information. The Pilots Handbook of Aeronautical Knowledge is not the most exciting reading, but should be a must for all pilots who are thinking of flying their own aircraft, or flying period. It is also good to read the Airplane Flying Handbook. Both are in expensive, under $16 and full of a wealth of flying knowledge that will prevent you from falling prey to the "well that is what this pilot told me" syndrome. Many many accidents and incidents with aircraft would have been prevented if pilots had just read first about what they were doing instead of trying to learn OJT! Colin & Bev Rainey KR2(td) N96TA Sanford, FL crain...@cfl.rr.com http://kr-builder.org/Colin/index.html
KR> Angle of attack
So, does the critical angle of attack change or not? Which is it, "This angle is known as the critical angle of attack, and this does not change for a particular wing." or "That changes the critical angle of attack for that wing loading, referred to as an accelerated maneuvering stall. "? Ken Jones \ - Original Message - From: "Colin & Bev Rainey" To: "KRnet" Sent: Monday, July 05, 2004 10:56 PM Subject: KR> Angle of attack > Netters > > Lets make this really simple:
KR> Angle of attack
Ken I know this sounds like I am talking out of both sides of my mouth, but no the critical angle of attack does not change, but the speed at which you will reach that angle does change if the wing loading is increased due to excess weight or maneuvers etc... If you think about a turn, you are using some of your vertical component of lift to turn, so you have to add back pressure to increase the angle of attack to replace the lost vertical lift that you are turning with. As the bank angle increases this replacement angle of attack gets to be quite excessive, and the load increases on the wing causing you to increase the lift even more by pulling back. This continues until you reach the critical angle of attack, but it will happen at a higher speed than in level flight attitude say in slow flight. The same thing occurs if you fly solo and note the stall speed and then load past your gross weight. You will see the speed at which you stall higher because you will reach the critical angle of attack sooner since it is requiring more lift to handle the higher weight to start with. The danger is approach speeds are higher, and landing speeds are higher, and if you do not take the increased weight into account when making your appoach, you could end up coming up short Colin & Bev Rainey KR2(td) N96TA Sanford, FL crain...@cfl.rr.com http://kr-builder.org/Colin/index.html
KR> Angle of attack (long)
At 11:16 PM 7/5/04 -0400, you wrote: >So, does the critical angle of attack change or not? > >Which is it, "This angle is known as the critical angle of attack, and this >does not change for a particular wing." or "That changes the critical >angle of attack for that wing loading, referred to as an accelerated >maneuvering stall. "? (Colin Rainey) > >Ken Jones + There is a key phrase that is being left out of this discussion that will help all to understand better. That phrase is "while maintaining altitude". Let's start a square one. A wing will only produce lift at an angle 90 degrees to it's span or straight up when the wing is level. It will also produce a given amount of lift depending on the speed through air and it's angle of attack (cord line to oncoming air). The air traveling across the top of the wing will always separate at a given angle or as we say, stall. If we bank the aircraft we take some amount of our vertical lift and vector it in a horizontal plane. This causes the aircraft to turn. At some point we vector enough vertical lift to the horizontal that the aircraft starts to lose altitude. As a pilot we increase the pitch angle (angle of attack) to create more lift to hold altitude. The additional lift creates more drag and the airspeed drops. We add more power to overcome the increased drag. As the bank angle increases the forces of the turn keep adding additional down forces that the wing lift must offset. To keep adding lift we can only add speed or increase the angle of attack. They each have their limit. The "angle of attack" is limited by when the air will separate on the top surface. The "speed" is limited by the wing structure and when the air loads would cause it to fail. I can put my wing at a bank angle of 90 degrees and low airspeed and not stall the wing if I keep the A of A below the speed where the air separates on the top surface. I can't maintain altitude with that bank angle but the wing won't stall. I'm sure you've all seen an airplane do "knife edge" flight. The wing is not stalled because it's being kept at or near a "zero" lift angle and the aircraft is kept in the air by lift generated by the fuselage and engine thrust and stored energy of speed. The reason you see a higher indicated airspeed at stall in a high banked turn is because you started at an airspeed higher than the stall speed for that bank angle " while trying to maintain altitude". The A of A at which it stalls is still the same. You reached that angle at a higher airspeed because you were trying to "maintain altitude". If I roll in to that same bank angle at five miles per hour indicated above level stall speed "and try to maintain altitude" I would get a stall immediatly but at a much lower indicated airspeed. The wing still stalled at the same A of A. Thus the advantage of the A of A indicator. I can fly every approach at the same A of A. My airspeed may be higher or lower depending on the aircraft weight on that flight and I can adjust rate of decent with power. The key is I won't be flying my approach at a fixed airspeed so when I'm really heavy I increase the A of A to generate enough lift at that airspeed and put the wing at near the stall A of A. In that situation if I increase my bank angle "and try to maintain altitude" by increasing the A of A of the wing it stalls, the ground rushes up to grab your a** and someone is left to pick up the rubble. Bottom line: The wing always stalls at the same A of A. One of my favorite maneuvers in the KR is what I call a wingover. I do a low G pullup into a rather steep climb. As the airspeed slows to about 80 mph indicated I roll into a near 90 degree bank. I release all back pressure on the stick so I don't feel any weight on the seat and let the nose fall through. I do a low G pullup from the dive and I've done a 180 degree turn. Some call this a "cotton patch" or "duster" turn. That's basicly how they do those fast turn-arounds without stalling when they are low and slow. They use stored energy of speed to keep them in the air and unload the wing in the turn. Once back to straight and level they increase the A of A to generate the lift they need to check their decent rate and return to level flight. If they don't have sufficent speed in the dive that A of A will be greater then the stall angle and the ground will reach up and grab their a** too. THE END Larry Flesner
KR>Angle of attack indicator
Folks A friend of mine designed his own AoA indicator. Simply a 1/2" tube, sealed at the end with row of small holes drilled into it. The tube is mounted out of the fuselage wall on the extended chord line 8"or so ahead of the leading edge root and is parallel to it. He has the holes pointed down at right angles to the chord so that at zero AoA there is minimal pressure in the tube. As the wing/fuselage is rotated to provide an AoA so too does the tube, the holes present to the air flow and the pressure increases. A reading is obtained on some sort of sensitive pressure gauge (maybe just a low speed ASI) that has it's face recalibrated in arbitary units (he just uses numbers 1 to 5 and has the dial named " partner's pressure level"). The tube can be rotated to provide calibration (or desired absolute needle movement) and the readings noted as he approaches the stall. He flies this gauge on approach, more so than the ASI. John The Martindale Family 29 Jane Circuit TOORMINA NSW 2452 AUSTRALIA phone: 61 2 66584767 email: johnj...@chc.net.au - Original Message - From: "larry severson" To: "KRnet" Sent: Wednesday, March 10, 2004 3:12 AM Subject: Re: KR>Dynon clarification > > >The only function you will not be able to use without adding an option is > >the Angle of Attack. The unit will provide all other functions with the > >expenditure of $1995 using the standard power supply in your airplane and > >the existing pitot/static system. If you have no use for the AOA, just > >use whatcha got. > > Forgive me, but the AOA is the most important feature that they add in not > only my opinion but also in a number of books on stalls, spins, landing and > small a/c crashes. > > > Larry Severson > Fountain Valley, CA 92708 > (714) 968-9852 > lar...@socal.rr.com > > > ___ > to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > please see other KRnet info at http://www.krnet.org/info.html >
KR>Angle of Attack Indicator-Gauge Option
Just because this is something I'm familiar with I thought I'd add some input to John's description of his friends homemade AoA's. The use of a low speed ASI in the cockpit as a gauge is a good one. Another option that could be used is a mini magnahelic gauge. These gauges are very common in industry and are used for heating and ventilating pressure readouts, induced air pressure measurement, etc. The gauges come in a variety of 'high-low' capacitys and ranges. Go to your yellow pages and look under 'Industrial Supply' or 'Heating and Ventilating Design'. If the firms you call don't sell them directly, they can tell you who does. I would also like to say that of all the different homemade AoA's that I've looked at and designed myself, I like this one the best, especially for it's 'tuning' capability. Thanks for posting John. Hope this is of help to someone. Peter Johnson KR-2Sexy with a Corvair Kenora, Ontario Canada mailto:pjohn...@voyageur.ca - Original Message - From: "Martindale Family" To: "KRnet" Sent: Tuesday, March 09, 2004 2:09 PM Subject: Re: KR>Angle of attack indicator > Folks > > A friend of mine designed his own AoA indicator. Simply a 1/2" tube, sealed > at the end with row of small holes drilled into it. The tube is mounted out > of the fuselage wall on the extended chord line 8"or so ahead of the leading > edge root and is parallel to it. He has the holes pointed down at right > angles to the chord so that at zero AoA there is minimal pressure in the > tube. As the wing/fuselage is rotated to provide an AoA so too does the > tube, the holes present to the air flow and the pressure increases. A > reading is obtained on some sort of sensitive pressure gauge (maybe just a > low speed ASI) that has it's face recalibrated in arbitary units (he just > uses numbers 1 to 5 and has the dial named " partner's pressure level"). > The tube can be rotated to provide calibration (or desired absolute needle > movement) and the readings noted as he approaches the stall. He flies this > gauge on approach, more so than the ASI. > > John
KR>Angle of attack indicator
What a neat idea, Virg On Wed, 10 Mar 2004 09:09:05 +1100 "Martindale Family" writes: > Folks > > A friend of mine designed his own AoA indicator. Simply a 1/2" tube, > sealed > at the end with row of small holes drilled into it. The tube is > mounted out > of the fuselage wall on the extended chord line 8"or so ahead of the > leading > edge root and is parallel to it. He has the holes pointed down at > right > angles to the chord so that at zero AoA there is minimal pressure in > the > tube. As the wing/fuselage is rotated to provide an AoA so too does > the > tube, the holes present to the air flow and the pressure increases. > A > reading is obtained on some sort of sensitive pressure gauge (maybe > just a > low speed ASI) that has it's face recalibrated in arbitary units (he > just > uses numbers 1 to 5 and has the dial named " partner's pressure > level"). > The tube can be rotated to provide calibration (or desired absolute > needle > movement) and the readings noted as he approaches the stall. He > flies this > gauge on approach, more so than the ASI. > > John > The Martindale Family > 29 Jane Circuit > TOORMINA NSW 2452 > AUSTRALIA > > phone: 61 2 66584767 > > email: johnj...@chc.net.au > - Original Message - > From: "larry severson" > To: "KRnet" > Sent: Wednesday, March 10, 2004 3:12 AM > Subject: Re: KR>Dynon clarification > > > > > > >The only function you will not be able to use without adding an > option is > > >the Angle of Attack. The unit will provide all other functions > with the > > >expenditure of $1995 using the standard power supply in your > airplane and > > >the existing pitot/static system. If you have no use for the > AOA, just > > >use whatcha got. > > > > Forgive me, but the AOA is the most important feature that they > add in not > > only my opinion but also in a number of books on stalls, spins, > landing > and > > small a/c crashes. > > > > > > Larry Severson > > Fountain Valley, CA 92708 > > (714) 968-9852 > > lar...@socal.rr.com > > > > > > ___ > > to UNsubscribe from KRnet, send a message to > krnet-le...@mylist.net > > please see other KRnet info at http://www.krnet.org/info.html > > > > > ___ > to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > please see other KRnet info at http://www.krnet.org/info.html > > Virgil N. Salisbury - AMSOIL www.lubedealer.com/salisbury Miami ,Fl
KR>Angle of Attack Indicator-Gauge Option
It´s the Dwyer Minihelic II, serie 5000 from Dwyer Instruments Inc. e-mail i...@dwyer.inst.com http//www.dwyer-inst.com If you want I have a draw of the sensor. It has two holes guided forward and they has 90° between it, so that the differential pressure measured among them is shown in the instrument. Eduardo - Original Message - From: "Peter Johnson" To: "KRnet" Sent: Tuesday, March 09, 2004 9:58 PM Subject: Re: KR>Angle of Attack Indicator-Gauge Option > Just because this is something I'm familiar with I thought I'd add some > input to John's description of his friends homemade AoA's. > > The use of a low speed ASI in the cockpit as a gauge is a good one. Another > option that could be used is a mini magnahelic gauge. These gauges are very > common in industry and are used for heating and ventilating pressure > readouts, induced air pressure measurement, etc. > > The gauges come in a variety of 'high-low' capacitys and ranges. Go to your > yellow pages and look under 'Industrial Supply' or 'Heating and Ventilating > Design'. If the firms you call don't sell them directly, they can tell you > who does. > > I would also like to say that of all the different homemade AoA's that I've > looked at and designed myself, I like this one the best, especially for it's > 'tuning' capability. Thanks for posting John. > > Hope this is of help to someone. > > Peter Johnson > KR-2Sexy with a Corvair > Kenora, Ontario > Canada > > mailto:pjohn...@voyageur.ca > > > - Original Message - > From: "Martindale Family" > To: "KRnet" > Sent: Tuesday, March 09, 2004 2:09 PM > Subject: Re: KR>Angle of attack indicator > > > > Folks > > > > A friend of mine designed his own AoA indicator. Simply a 1/2" tube, > sealed > > at the end with row of small holes drilled into it. The tube is mounted > out > > of the fuselage wall on the extended chord line 8"or so ahead of the > leading > > edge root and is parallel to it. He has the holes pointed down at right > > angles to the chord so that at zero AoA there is minimal pressure in the > > tube. As the wing/fuselage is rotated to provide an AoA so too does the > > tube, the holes present to the air flow and the pressure increases. A > > reading is obtained on some sort of sensitive pressure gauge (maybe just a > > low speed ASI) that has it's face recalibrated in arbitary units (he just > > uses numbers 1 to 5 and has the dial named " partner's pressure level"). > > The tube can be rotated to provide calibration (or desired absolute needle > > movement) and the readings noted as he approaches the stall. He flies this > > gauge on approach, more so than the ASI. > > > > John > > > > ___ > to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > please see other KRnet info at http://www.krnet.org/info.html > --- > [This E-mail scanned for viruses by Declude Virus] > > > --- [This E-mail scanned for viruses by Declude Virus]
KR>Angle of Attack Indicator-One Problem
I must apolgise for not seeing this sooner. The AoA sensor that John described is a great idea, but it won't work (or is not accurate) in the location he described it to be. The AoA sensor must be out of the propwash flow! "Duh!" Such a tube could be easily mounted beneath the wing in a horizontal fashion, with one hole on the bottom and one on the side or front. Someone has already posted a sketch of this layout in the past, and it's the way the production models work. Do a google search for 'reserve lift indicators' and you will come to a site right away that has an image of their commercial sensor. Thanks for the info on the mini magnahelic Eduardo. PJ mailto:pjohn...@voyageur.ca - Original Message - From: "Eduardo M. Iglesias" To: "KRnet" Sent: Wednesday, March 10, 2004 6:26 AM Subject: Re: KR>Angle of Attack Indicator-Gauge Option > It´s the Dwyer Minihelic II, serie 5000 from Dwyer Instruments Inc. > e-mail i...@dwyer.inst.com http//www.dwyer-inst.com > If you want I have a draw of the sensor. It has two holes guided forward and > they has 90° between it, so that the differential pressure measured among > them is shown in the instrument. > Eduardo > > - Original Message - > From: "Peter Johnson" > To: "KRnet" > Sent: Tuesday, March 09, 2004 9:58 PM > Subject: Re: KR>Angle of Attack Indicator-Gauge Option > > > > Just because this is something I'm familiar with I thought I'd add some > > input to John's description of his friends homemade AoA's. > > > > The use of a low speed ASI in the cockpit as a gauge is a good one. > Another > > option that could be used is a mini magnahelic gauge. These gauges are > very > > common in industry and are used for heating and ventilating pressure > > readouts, induced air pressure measurement, etc. > > > > The gauges come in a variety of 'high-low' capacitys and ranges. Go to > your > > yellow pages and look under 'Industrial Supply' or 'Heating and > Ventilating > > Design'. If the firms you call don't sell them directly, they can tell > you > > who does. > > > > I would also like to say that of all the different homemade AoA's that > I've > > looked at and designed myself, I like this one the best, especially for > it's > > 'tuning' capability. Thanks for posting John. > > > > Hope this is of help to someone. > > > > Peter Johnson > > KR-2Sexy with a Corvair > > Kenora, Ontario > > Canada > > > > mailto:pjohn...@voyageur.ca > > > > > > - Original Message - > > From: "Martindale Family" > > To: "KRnet" > > Sent: Tuesday, March 09, 2004 2:09 PM > > Subject: Re: KR>Angle of attack indicator > > > > > > > Folks > > > > > > A friend of mine designed his own AoA indicator. Simply a 1/2" tube, > > sealed > > > at the end with row of small holes drilled into it. The tube is mounted > > out > > > of the fuselage wall on the extended chord line 8"or so ahead of the > > leading > > > edge root and is parallel to it. He has the holes pointed down at right > > > angles to the chord so that at zero AoA there is minimal pressure in the > > > tube. As the wing/fuselage is rotated to provide an AoA so too does the > > > tube, the holes present to the air flow and the pressure increases. A > > > reading is obtained on some sort of sensitive pressure gauge (maybe just > a > > > low speed ASI) that has it's face recalibrated in arbitary units (he > just > > > uses numbers 1 to 5 and has the dial named " partner's pressure level"). > > > The tube can be rotated to provide calibration (or desired absolute > needle > > > movement) and the readings noted as he approaches the stall. He flies > this > > > gauge on approach, more so than the ASI. > > > > > > John > > > > > > > > ___ > > to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > > please see other KRnet info at http://www.krnet.org/info.html > > --- > > [This E-mail scanned for viruses by Declude Virus] > > > > > > > > > --- > [This E-mail scanned for viruses by Declude Virus] > > > ___ > to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > please see other KRnet info at http://www.krnet.org/info.html
KR>Angle of attack indicator
Sport Aviation 1/79 described a working model of an angle of attack indicator with drawings. Perhaps someone with a scanner and a link facility could make both this and the older article available on the list. I will do the scanning, if it would help. Thanks. Norman Seel Brandon, FL norman.s...@verizon.net - Original Message - From: "Virgil Salisbury" To: Sent: Wednesday, March 10, 2004 10:59 AM Subject: Re: KR>Angle of attack indicator > What a neat idea, Virg > > On Wed, 10 Mar 2004 09:09:05 +1100 "Martindale Family" > writes: > > Folks > > > > A friend of mine designed his own AoA indicator. Simply a 1/2" tube, > > sealed--- > > The Martindale Family > > 29 Jane Circuit > > TOORMINA NSW 2452 > > AUSTRALIA > > > > phone: 61 2 66584767 > > > > email: johnj...@chc.net.au > > - Original Message - > > From: "larry severson" > > To: "KRnet" > > Sent: Wednesday, March 10, 2004 3:12 AM > > Subject: Re: KR>Dynon clarification > > > > add in not > > > only my opinion but also in a number of books on stalls, spins, > > landing > > Larry Severson > > > Fountain Valley, CA 92708 > > > (714) 968-9852 > > > lar...@socal.rr.com > > > > > > > > > ___ > > > to UNsubscribe from KRnet, send a message to > > krnet-le...@mylist.net > > > please see other KRnet info at http://www.krnet.org/info.html > > > > > > > > > ___ > > to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > > please see other KRnet info at http://www.krnet.org/info.html > > > > > > > Virgil N. Salisbury - AMSOIL > www.lubedealer.com/salisbury > Miami ,Fl > > ___ > to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > please see other KRnet info at http://www.krnet.org/info.html
