realair lancair stall recovery

[yankeegolf3 52]

Hi,

 

I am a bit surprised at the lancair stall modelisation.  Here is my case:

11000 ft 120kt fuel 70%. I start a power off stall. I reduce power ,the speed decreases as I maintain my altitude with the stick. At 80 kt, I have the stall warning, the aircraft shudders. I gently push the stick forward, at 10000 ft, my speed reaches 125 kt, I pull the stick gently, apply power, to no avail, the aircraft sinks nose down and whatever I do with the controls the aircraft keeps diving nose down. I don't enter a spin, nor a secondary stall, it is only that the aircraft controls are ineffective.. I can replicate this behaviour at most of the power off stall that I make. I've never experienced this with any aircraft in FSX. It is as if I was in a deep stall but in a nose down attitude instead of a nose up attitude (for the deep stall).  What do you think?

THX

[Bert Pieke 7,594]

I think I would extend the speed brakes, gear, flaps, and start looking for the parachute handle...

[ryanbatc 13,098]

What happens if you push the nose down farther when the stall horn goes off?

[DeskPilot518 15]

Ok,

Just did a few stall test with the Lacair over the Flytampa Grenadines scenery.

(Now that I have a new computer I can finally enjoy theses types of scenery packs, and the Lancair!!!)

 

1st, replicated the OPs first test flight at 11,000 ft with 90 percent fuel, power off stall!

At around 80 knots, went into stall!

 

Tried to level out at 120 kts at 10,000 but couldn't as the plane plunged farther and farther down! Virtually it was scary, well, Atleast this was not a real flight, thank goodness!! Broke the stall at 4000 ft with gear and speed brake out! Yes, I plunged that far! Didn't see that coming : (

 

Then I got an idea : )

 

2nd test, 11,000 ft, 88 percent fuel, power off stall which occurred around 80 knots.

As plane plunged I nosed her down and let airspeed reach the white marked zone around 160 to 170 TA. With full power on she came out of stall at 8800 feet!

 

Conclusion:

Given RealAir's reputation the Lancair probably recovers from a stall as she should.

You probably need to speed up to Atleast 160kts to reform the airflow over her wing when flying clean. Atleast this is my guess, but whether I am right or wrong, you will need to speed her up past 120kts to break the stall when clean in the sim. It would be interesting to research the real Lancair's stall properties.

[BeechPapa 32]

Not sure if you guys have researched the real-life Lancair Legacy, but its known to be a bit of a handful, with a higher accident rate than other kit airplanes of the same category, Some people blame this on the fact that the plane is advertised for long range cruising and is IFR capable and yet can't handle weather or extreme turbulence and doesn't have pressurization to go above weather either... so it lulls pilots into bad situations. The other thing that makes this a dangerous plane is the stall behavior. It has an extremely fast  highly loaded wing with minimal drag, so its not the most-lift happy wing out there. According to many Lancair pilots I've seen comment on forums, or quoted in forums, the stalls happen very quickly and they are not mild nose-down stalls, a wing usually drops. Its at this point (according to what I read) you must not fight the controls, i.e. don't try to bring her wings level again or pitch up, just roll through the stall and keep it from spinning by applying opposite rudder to the spin. Once you are stabilized (nose down) bring the throttle back up and slowly bring the elevators up too. Just because you are above stall speed at 140kts or so doesn't mean the stall is over. You still aren't back in your flight envelope. What kills alot of RL Lancair pilots is the fact that sometimes they stall on approach and don't have the altitude to perform a split S (which is basically what is required to recover from these kinds of violent stalls). The airplane can bite really hard. I'm glad Real Air models this so accurately, this is what a proper flight modeling is all about, and why I keep buying their products.

[DeskPilot518 15]

Thank you for the information.

 

Now that I am getting some really good flying in with the Lancair, I can see that she can be a handful. Not that I did not expect this given the wing design as you mentioned.

She reminds me of some of the early WW2 fighters in this respect.

 

Not a plane I would take my family out in if even if I had a pilots license (or the money for the plane). But in the Sim I really like the speed and the view from the large canopy.

[yankeegolf3 52]

Not sure if you guys have researched the real-life Lancair Legacy, but its known to be a bit of a handful, with a higher accident rate than other kit airplanes of the same category, Some people blame this on the fact that the plane is advertised for long range cruising and is IFR capable and yet can't handle weather or extreme turbulence and doesn't have pressurization to go above weather either... so it lulls pilots into bad situations. The other thing that makes this a dangerous plane is the stall behavior. It has an extremely fast  highly loaded wing with minimal drag, so its not the most-lift happy wing out there. According to many Lancair pilots I've seen comment on forums, or quoted in forums, the stalls happen very quickly and they are not mild nose-down stalls, a wing usually drops. Its at this point (according to what I read) you must not fight the controls, i.e. don't try to bring her wings level again or pitch up, just roll through the stall and keep it from spinning by applying opposite rudder to the spin. Once you are stabilized (nose down) bring the throttle back up and slowly bring the elevators up too. Just because you are above stall speed at 140kts or so doesn't mean the stall is over. You still aren't back in your flight envelope. What kills alot of RL Lancair pilots is the fact that sometimes they stall on approach and don't have the altitude to perform a split S (which is basically what is required to recover from these kinds of violent stalls). The airplane can bite really hard. I'm glad Real Air models this so accurately, this is what a proper flight modeling is all about, and why I keep buying their products.

 

I've done some internet research about the lancair 's stall behaviour and what I 've read on 2 flight test reports is nowhere near what we experience with the realair lancair.

 

http://lancairlegacy.com/Gallery_images/CAFE_Legacy_report.pdf

 

http://lancairlegacy.com/Gallery_images/Legacy_article.pdf

 

I am puzzled because the modelisation seems to be incorrect. I may contact Rob in order to clear  that up.

 

THX

[DeskPilot518 15]

Interesting! From the first PDF

 

Stalls were explored at 9,000 ft using 8" MP to establish an approximately a 1 knot per second rate of deceleration. The clean configuration stalls occurred crisply after mild aft stick force b u i l d - u p a n d w i t h l i t t l e a d v a n c e d w a r n i n g . At the moment of stall the right wing dropped approximately 30 degrees but this became controllable using both rudder and aileron as the angle-of-attach was reduced. The resulting nose drop would cause only about 150 feet of altitude loss provided that the stall recovery input was commenced immediately.

[BeechPapa 32]

She reminds me of some of the early WW2 fighters in this respect.

 

Not a plane I would take my family out in if even if I had a pilots license (or the money for the plane). But in the Sim I really like the speed and the view from the large canopy.

I tend to think of her as a mini-WW2 fighter as well, just maybe a tad more forgiving. It's amazing fun in FSX but it would not be my choice in personal aircraft either. I've seen NTSB/ATSB reports of Lancair accidents with pilots that had military experience and thousands of hours being killed by stalls/spins during stall recovery practice as high as 6,000ft. When a pilot with that kind of experience gets into a situation he knew was coming, and still can't get out of it within 6,000ft, that says a lot about the airplane. As beautiful and fun as she is, I wouldn't put family members into one either. Just my 2 cents.

 

 

I've done some internet research about the lancair 's stall behaviour and what I 've read on 2 flight test reports is nowhere near what we experience with the realair lancair.

 

http://lancairlegacy.com/Gallery_images/CAFE_Legacy_report.pdf

 

http://lancairlegacy.com/Gallery_images/Legacy_article.pdf

 

I am puzzled because the modelisation seems to be incorrect. I may contact Rob in order to clear  that up.

 

THX

Very cool finds, thanks for posting these. I wouldn't say the Real Air version is completely off the CAFE report, but it seems to allow for more buffeting before the wing snaps. Your CAFE report mentions a 1kt/second rate of deceleration with 1kt of buffet warning, so the buffeting should only last 1 second before the stall happens and the nose and wing drop. It seems to me the real air version buffets a little longer before you lose stability. They already make some of the most unforgiving sim planes on the market (along with A2A) but if they can make the onset of the stall happen a little quicker that would be nice.  

[mgh 89]

The fact is that the FSX flight dynamics model is not capable of simulating a spin accurately. Some developers tweak the .air file to give the impression that the aircraft is spinning realistically.

[robert young 2,897]

Recovery will occur with a positive forward movement of the stick until the stall is fully recovered. This might mean a slightly more positive forward movement than on the real thing, until the stall buffet/buzzer ceases. It is not dependent on airspeed but angle of attack. The more up trim you have the more positive forward movement you need. The quicker you initiate the forward movement the quicker the stall will recover without speed building up. It is unrelated to power or airspeed but wing angle of attack. FSX is not perfect in this regard and up trim has an exaggerated influence where it shouldn't.

 

Hope you don't mind me repeating some of a recent post on a similar thread:

 

I think if people want to be ultra picky about this sort of thing, they might like to start with some basic flaws in default GA aircraft which we have worked tirelessly to overcome for years, like:

 

Almost completely locked yaw in the air, so no side slip at all

No buffeting at all at the stall

Very little wing drop at the stall, if any 

Inability to spin due to locked yaw

Almost no accelerated stall

Pitch control over sensitive and bouncing up and down like an elasticated yo-yo

No ability to provoke a reasonable approximation of a spin

Sudden ballooning off the runway at take off due to over-sensitive pitch control

...and many more

 

The price paid for some of the above is that you do need a positive forward movement to stop the stall, and there's a slightly bigger altitude loss on recovery. I think that is a small price for all the advantages we've developed over the years. But the biggest problem (for me) with FSX's flight modelling core is that trim does not properly work merely to relieve the need for back pressure on the stick. It actually creates more pitch/elevator moment and if you set high enough trim at the stall it then needs more positive forward movement to stop the stall and recover. In a real aircraft high trim at the stall just requires more forward pressure, but not much more forward movement as a whole.

 

Interesting to note that some accidents over the years have possibly been caused by the autopilot trim raising the nose more and more due to loss of airspeed on approach, resulting in a flat spin or stall which results in a nose up descent all the way to the ground, or the pilot refusing to push forward at the stall when flying manually (ATR approach in cold weather, Trident stall/crash near Heathrow, Recent San Francisco B777 episode, possibly Air France Airbus over the sea in a storm, and many more). In these cases a very positive forward movement (and in some case more power) would have saved the situation. The deeper the stall the more positive forward movement is required, and the Legacy attempts to emulate that. In an incipient or not fully developed stall just a little forward pressure stops the stalled state.

 

FSX is pretty good for a sub million dollar simulator despite some F/M flaws and one can't expect miracles. 

[BeechPapa 32]

Rob, despite our nitpicking, I’m sure myself and everyone who purchases your products values the efforts you and Sean have put into your planes. The list of problems you overcame in GA aircraft is the same list of features that drove me to start buying your products to begin with. They are some of the few on the market that provide the accelerated stalls, buffeting, and wing drops you mention, as well as adverse yaw, and AOA/airspeed penalty for skidded turns. These are advanced features and nobody is taking them for granted. Since the flight model is so advanced, comparisons to the real thing are to be expected, and the very fact that your Lancair Legacy can be compared so closely to real life Lancair Legacy testing says a ton in and of itself. There may be a few things all of us wish could be improved upon (including yourself) but that’s not to say we don’t appreciate Real Air products for the amazing things they accomplish in a limited FSX environment, or take those accomplishments for granted.

 

In regards to the airliner incidents you mentioned, while flying the PMDG777 I accidentally replicated the B777 SFO incident (a euphemism for saying I screwed up royally) coming into TNCM. The plane was set on an AP mode that forced the throttles into idle while simultaneously trimming for 0 degree pitch. It was completely my fault, but a critical oversight nonetheless. Though I realized the plane was stalling, it was too late for recovery, and the plane hit the water flat as a pancake. So I certainly do see the danger of AP trim, especially if the pilot isn’t paying enough attention (which I wasn't even close to doing).          

[robert young 2,897]

Rob, despite our nitpicking, I’m sure myself and everyone who purchases your products values the efforts you and Sean have put into your planes. The list of problems you overcame in GA aircraft is the same list of features that drove me to start buying your products to begin with. They are some of the few on the market that provide the accelerated stalls, buffeting, and wing drops you mention, as well as adverse yaw, and AOA/airspeed penalty for skidded turns. These are advanced features and nobody is taking them for granted. Since the flight model is so advanced, comparisons to the real thing are to be expected, and the very fact that your Lancair Legacy can be compared so closely to real life Lancair Legacy testing says a ton in and of itself. There may be a few things all of us wish could be improved upon (including yourself) but that’s not to say we don’t appreciate Real Air products for the amazing things they accomplish in a limited FSX environment, or take those accomplishments for granted.

 

In regards to the airliner incidents you mentioned, while flying the PMDG777 I accidentally replicated the B777 SFO incident (a euphemism for saying I screwed up royally) coming into TNCM. The plane was set on an AP mode that forced the throttles into idle while simultaneously trimming for 0 degree pitch. It was completely my fault, but a critical oversight nonetheless. Though I realized the plane was stalling, it was too late for recovery, and the plane hit the water flat as a pancake. So I certainly do see the danger of AP trim, especially if the pilot isn’t paying enough attention (which I wasn't even close to doing).          

 

 

I think nearly all of us at some point have done the same thing! More likely with larger jets as they tend to be on a/p more than GA aircraft. Thanks for your kind comments.

[yankeegolf3 52]

Recovery will occur with a positive forward movement of the stick until the stall is fully recovered. This might mean a slightly more positive forward movement than on the real thing, until the stall buffet/buzzer ceases. It is not dependent on airspeed but angle of attack. The more up trim you have the more positive forward movement you need. The quicker you initiate the forward movement the quicker the stall will recover without speed building up. It is unrelated to power or airspeed but wing angle of attack. FSX is not perfect in this regard and up trim has an exaggerated influence where it shouldn't.

 

 

Thank you Rob for replying.

 

I followed your advice regarding the positive forward movement of the stick and it worked. As soon as the AOA gauge pointer was in the yellow area, I gently pulled back the stick to regain lift. Starting the stall at 9500 ft/80 kt (70% of fuel), I succesfully recovered 5 times out of 5  at 8300 ft with a maximum IAS of 145 kt and a maximum VS of 4000 ft/mn. The key was to forget about the frightening nose down attitude and high vertical speed in order to maintain the AOA in the yellow area. Stall recovery in the Lancair is not as easy as with other aircraft. I am gald I am now able to survive stalls!!!

[robert young 2,897]

Thank you Rob for replying.

 

I followed your advice regarding the positive forward movement of the stick and it worked. As soon as the AOA gauge pointer was in the yellow area, I gently pulled back the stick to regain lift. Starting the stall at 9500 ft/80 kt (70% of fuel), I succesfully recovered 5 times out of 5  at 8300 ft with a maximum IAS of 145 kt and a maximum VS of 4000 ft/mn. The key was to forget about the frightening nose down attitude and high vertical speed in order to maintain the AOA in the yellow area. Stall recovery in the Lancair is not as easy as with other aircraft. I am gald I am now able to survive stalls!!!

 

Excellent news. Thanks for confirming.