Series 5 Tailplane stall

[n85ae]

I posted this on the other list, here's a heads up to something that happened
to me.

My plane is a Series 5, with IO-240B and with Trim Assist spring.

I was out of 8500 feet descending through a hole in the clouds, steep
nose down with 11 degrees of flaperons, and trimmed. Speed started to build
so I tugged in 22 degrees at about 80+ mph (something I normally do
not do, but I wanted to see if they'd slow the plane). What happened next
was with absolutely no warning.

Few seconds later I was holding a bit of stick pressure to keep the same
nose down attitude. Then with no warning stick control went away and
the nose dropped violently down, and everything in the plane hit the ceiling
or inside of the windshield. I hit my legs into the bottom of the instrument
panel and slammed up in my straps.

I'm pretty sure it went past vertical, and I grabbed the flaperon handle and
pushed it back out of 22, and got the stick forward a bit. Somehow I ended
in a nose down vertical dive and got it back under control. By the time I
pulled out I'd lost well over a thousand feet.

Pretty sure my flaperons blanked the tail, and it tailplane stalled. But I can't
say for sure. Anyway had it been in the pattern I'd have been dead. Which
very well could happen, as I've often thought to tug in 22 degrees
on a fast descent to try to slow down. But luckily never did do it.

I'll let the list figure out what happen, or the test pilots in the lot. Anyway
my personal opinion is that the variable incidence tail, with heavy nose,
the spring assist and too much flaperons all at the wrong time can put you
tail over nose in a bad way, a lot faster than you can imagine.

Regards,
Jeff Hays

[SkyPirate]

Glad you had the altitude to correct it Jeff,..your analogy is probably right on,..as long as the main wing has plenty lift,..the vorticies follow the trailing edge out to the tip then seperate,..when you decend to the point the wing is making some nasty air especially with flap, that can hit the tail surfaces,..I'm sure at your rapid decent the tail flew down into it ,.. an example if you do a loop and you fly back into the wash the wing made at the bottom when you first pulled back on the stick for the loop ..you hit a good bump ,..even though you didnt do a loop ..your decent was from the sounds of it at the same speed down as forward,.so it's basically the same result except you didnt just fly through it ..your tail was in it,..if that makes sense :)

[jtpitkin06]

I'm sure this all happened in a flash and it may be difficult to remember. I'll need some more info before making an analysis.

When holding the stick pressure to keep the same nose down attitude, which way? Forward pressure or back pressure?

Next, did you lose the roll control too, or just pitch control?

When you moved the flaperons out of 22 you state "got the stick forward a bit:." Why? Was the nose coming up or was this just instinct to lower the nose when the airplane stalls?

[n85ae]

I've replayed it in my mind a thousand times, and what I did was not that
dramatic, but what happened was. Maybe it was a fluke, and nobody else
will ever have it happen. Anyway, the moment it tossed over like that, I
really had no time to think at all. I don't know how I even reached the
flaperon handle as everything including me was trying to go out the roof.

Regards,
Jeff

[n85ae]

Here's my recollection:

With all that flaperon, even trimmed my plane pitches nose down, so
I was holding some back pressure, When it pitched over the stick
pressure slackened.

It pitched over straight ahead. No bank, or yaw.

I grabbed for the flaperon handle, and all I could manage was to just get
it release from 22 and it snapped forward into 11 degrees position. It was
hard to grab the handle as I was up by the overhead tubing since my seat
belt was not super tight

I pushed forward on the stick out of instinct, but it was so nose over that
I really felt like pulling. This just seemed at the moment the thing to do.
I really did not think about it.

Pretty soon after that the controls stiffened back up, and I started pulling
out around this point I started consciously thinking not to overstress the
plane. However before this, I really didn't think about much



I'm sure this all happened in a flash and it may be difficult to remember. I'll need some more info before making an analysis.

When holding the stick pressure to keep the same nose down attitude, which way? Forward pressure or back pressure?

Next, did you lose the roll control too, or just pitch control?

When you moved the flaperons out of 22 you state "got the stick forward a bit:." Why? Was the nose coming up or was this just instinct to lower the nose when the airplane stalls?

[jrevens]

I had a similiar experience in an entirely different airplane. It occured with a forward CG situation (almost at the limit) test flight, while doing full-flap power-on stalls. The down force created by the elevator to maintain a very high nose angle was evidently considerable, and when disturbed air from the flaps destroyed that force (a classic elevator stall), it stayed that way even after the the pitch-over, which was dramatic & violent - I would describe it as similiar to an "English Bunt" maneuver. It felt like the elevator control had broken. The wing was flying. I was going straight nose down, & if I hadn't retracted the flaps I would have ridden it right into the ground. If I had had electric flaps instead of that good old flap handle staring at me, I'm not sure I would have done the right thing in time. Beware of forward CG, high AOA, and potential air-disturbing devices such as flaps.

I don't know if this is at all helpful on this forum, but Jeff's experience sure brought back memories.

[n85ae]

Hi -

That sounds very similar to what I had happen. Not the kind of thing you
expect. Just one second your flying along, and the next it's "Whoa, what
heck ..."

Where do you fly from? I learned to fly out at KBJC and get out there a
couple times a year.

Regards,
Jeff

[rogerh12]

Is this Flap induced Elevator Stall caused mostly by the inboard section of the flaps?

[jtpitkin06]

Thank you for sharing your incident with us. I hope others can learn from your experience.

I believe you experienced flap overspeed.

All airfoils have a maximum speed limit. The reason for the limit can be structural, where flutter can destroy the airframe in seconds; or, aerodynamic, where controlability becomes an issue. The aircraft might become super sensitive or non-responsive.

Let’s see if we can clear up what probably happened to you.

Extending flaps or flaperons dramatically increases the camber and extends the chord. Both changes move the center of lift aft. The center of lift shifting aft pitches the aircraft forward.

The pilot normally corrects for the forward pitch by trimming nose up. Some aircraft are unable to put in sufficient nose up trim requiring the pilot to hold a small amount of back pressure. Because the aircraft is not in trim it is easy for the speed to increase when the pilot’s attention is diverted.

When a wing produces lift, some air is deflected downward in the form of a wake. The wake or downwash aids the down force normally required by the stab/elevator to maintain pitch.

At higher speeds, with flaps/flaperons extended, pitch control becomes very sensitive. The amount of downwash can change very quickly, up or down, with small inputs from the elevator. The pilot can get into pilot induced oscillations with almost imperceptible inputs.

Elevator stick pressure may become very light due to rapid changes in downwash forces. It is possible for the aircraft to pitch up rapidly when exceeding the maximum flap speed resulting in excessive G forces. The aircraft may also pitch down rapidly leading a pilot to think the elevator has stalled. A rapid pitch down lowers the amount of downwash on the elevator. The pitch control may suddenly feel “mushy” even though it is still functional.

This phenomenon is not a blanking of the tail or a stalling of the stab. It is a case of flap overspeed where pitch control becomes extremely sensitive. It is not something peculiar to the Kitfox. It can happen in any aircraft equipped with flaps or flaperons.

To recover from flap overspeed the pilot must slow the aircraft or reduce the flap extension. Immediate speed reduction with steep negative pitch is almost impossible, so flap reduction is the action of choice.

You were very sharp to dump the flaps. Doing so put the aircraft back into a controllable state with partial flaps. Atta Boy!!!

The rapid pitch down slammed you upward with negative G’s. The sensation was the same as you might get from an accelerated stall. Your instinctive reaction from all your previous flight training was to lower the nose. I can’t fault you for that as you were in your own corner of uncharted territory.

I suspect your aircraft accelerated beyond the maximum flap speed with just a moment of inattention while you were looking at your descent path. It can occur very easily when near the maximum if you are out of trim. If your target speed was 80 you could easily pop up to 90, 100 or more in a blink.
We tend to think of the red line as the only maximum speed limit. We see that the maximum speed for flaps at the top of the white arc is just as important as the ultimate red line.

I ‘m pretty confident a flap overspeed is what happened to you. We’re happy you are here to share your story.

Regards,
John Pitkin

[n85ae]

That makes sense. I initially thought I'd done some kind of high speed stall,
then I started thinking tailplane stall. I'm still not sure, it was not particularly
pitch sensitive. I'd say it felt positive in control until the moment there was
no control.

I was very aware of the flaperons as I had dumped them in intentionally, so
it wasn't requiring much thought when it happened that they had caused it.

John at Kitfox said he was going to see if he could reproduce it based on my
description, if he does I'm sure he'll let me know. If so I'll post what he finds.

Regards, Jeff Hays

[SkyPirate]

well put JP,..we might need to check your lineage lol there might be some bernelli back there somewhere :)

[n85ae]

Less than the speed at which I extended them. I'm not saying I did the right
thing, I'm simply saying what I did and what happened.

Regards,
Jeff

[Dorsal]

Or perhaps some Bernoulli (sorry Chase, just busting your chops)

Jeff, Let me also say thanks for posting this, I rarely use the 2nd notch of flaps but I will be paying closer attention now.

[kmach]

Is there no placarded speeds for flap extension in a V?

Hi,

in my series 5 the maximum flap extension speed is listed and marked as 80 mph, I usually only apply flaps on final and below 80 mph.

I am very glad to hear that this story has a live ending

[n85ae]

I don't recall the exact speed, BUT it was definetly less than 100 I'd
say in the 80-90 range. I didn't just yank the handle at cruise speed,
this I can say for sure.

I honestly did not think I was going that fast, as I had already pulled
in 11 degrees, and trimmed the plane. I pushed over steeper, speed
started to build so I pulled in 22 held some back pressure with the
stick I honestly don't remember if I continued trimming, but I do recall
the stick went slack, and all hell broke lose at the same time.

Regards,
Jeff

[SkyPirate]

What matters Jeff ,..is that you knew how to fix it :) and your hear to tell us about it

[n85ae]

Thanks, I'm glad to still be here too. :)

Regards,
Jeff

[SkyPirate]

that was one of those sphyncter checks that when you get on the ground ..the sky looks bluer ..the flower smell better,..ugly women look cuter ..ok I'll retract that one ugly women are still ..ugly women lol

[n85ae]

I distinctly remember thinking that this is what people feel in that last fatal
stall spin. Then yes when I was sitting in the plane under control again
feeling really glad to be alive. :)

Regards,
Jeff

[szicree]

Not claiming any fancy expertise here, but from reading your account I don't think the problem was specifically due to being too fast, but rather from stumbling onto the exact combination of speed, descent angle and attitude to send the h.stab right through the extremely turbulent wake of your flaps. Once that happened, the normal downforce on the tail was lost and the pitching moment of the flapped wings took over. I suspect that the tail would have found clean air again once you were heading for the dirt even if you had done nothing. Good thing you had plenty of sky underneath you. Glad it worked out and I look forward to some factory testing on this phenomenon.

[n85ae]

I landed it without any flaperons on a long straight in landing like the wings
were just about to fall off. This weekend will be a very thorough exam.

I'm also removing the trim assist spring, and putting a mechanical block
on the flaperon lever. Some may argue this, but I suspect that without the
spring, or having 22 degrees available it would never have happened.

[jrevens]

I am based at KBJC... been there for 21 years with the first airplane I built. I also learned to fly there in the early 1970's. It's a small world.

A further comment about my experience... my elevator was not just partially ineffective - it was, as I said, as if there was a total disconnect. The stick was floppy-loose fore & aft. The strange thing was that the condition continued, going straight down & close to exceeding red-line, until the flaps were retracted. No other control inputs nor throttle changes had any effect. It evidently stabilized in an attitude/AOA where the tail remained in a stalled condition.

Again, I apologize, as this is not Kitfox specific, but I hope it might be useful in some way.



Hi -

That sounds very similar to what I had happen. Not the kind of thing you
expect. Just one second your flying along, and the next it's "Whoa, what
heck ..."

Where do you fly from? I learned to fly out at KBJC and get out there a
couple times a year.

Regards,
Jeff

[Dorsal]

Not sure how the spring assist could have effected this though I can definitely appreciate preventing full flaps after that experience.

[n85ae]

In my opinion the Spring assist, tricks you into holding more pressure than
you should. That stick force when you pull in the flaperons is telling you
something, which maybe just pulling harder isn't the best solution to. The
spring mechanically pulls for you.

It did not cause what happened, but I think it helped assist me to get in a
place that caused what happened. If that make sense.

Jeff

[n85ae]

I have the variable incidence tail. It works well enough, but is a bit sensitive.
I'll give the plane a solid look over this weekend make some minor changes
as I mentioned and take it out and do some flying. It's always been a very
easy flying airplane with no bad habits until I used that 22 degrees flaperons.

I really never needed them before, so if not using them is all it take to prevent
another upset like that then that's my solution.

I will have to do some thinking about baggage stowage. Just tossing stuff in
the back is not good enough I can say now.

Regards,
Jeff

[rogerh12]

If going too fast with too much flaps is a issue, is there a kitfox "known safe" maximum flap position where one does not need to worry about going too fast with flaps extended? That is to say, the plane would reach Vne anyway before the flap down angle would present any additional elevator control issues due to speed. Sort of a , no-wories-mate flap angle.

Or maybe you have personal flight experience where you were technically going too fast for flaps, but had them deployed to some degree anyway, with any adverse flight effects.

Roger

[Dave Holl]

Hi all
A very scary moment:eek:
Here in the uk we have to limit the flap to the first position.
I would have a good look at the flaperon hangers to ensure no cracks or distortion.
I had an loss of pitch stability event a few years back in my Jodel aircraft where by missmanagement of the fuel, quater in front tank and full in rear with one rear seat pax on slowing up to join the circuit(patten) the stick went very slack in my hand and for a moment I thought the elevator control had become disconnected the aircraft slowley pitched down and eveything became normal! After on the ground I checked the weight and balance and it was right on the aft limit.
I must say I was glad to be on the ground
Dave:)

[av8rps]

After flying a multitude of Kitfoxes and Avids for over 25 years, and doing just about anything you can imagine with one, I believe that this situation was likely caused by a tail stall, and not the flaperons.

Unlike many that think our flaperons are useless, I use flaperons for every takeoff and landing (I've adjusted my flaps so I get nearly 30 degrees of throw). And yet, I've never experienced anything that I would say is unusual or scary.

Here's just one example of the extent I've tested my flaperons; I recently blew out (!) both back quarter windows on my Kitfox amphib while practicing SEVERE full flap slips in both directions in an effort to figure out how to land my speedy little amphib shorter. (I began the testing at high altitude to be safe. I didn't want to learn at low altitude that my severe fuselage angle combined with a slow airspeed, a huge sink rate, and totally uncoordinated flight would result in something like a snap roll). But even in that situation, the Kitfox was solid and stable.

Oh yeah, I have also mistakenly had my flaps on as high as 100 mph and never had an issue. Once the flaps actually took themselves off from the air pressure caused by the speed.

So I think you hit the nail on the head when talking about the tail stall.

Thank you for sharing this information Jeff. It is very good for all of to know. And if it happened to you, it can happen to others.

[CDE2FLY]

Jeff - really glad you were able to share your experiance....I'm sure we'll all be on heightened alert with regards to the use of high angle flap settings....especially at higher speeds!

Ironically, the night you posted, I had been out flying my Model 7 and although I rarely use the 22 degree flap setting, I had been experimenting by pulling 22 degrees on final (65-70 mph) to determine under what conditions the higher flap settings might be helpful. In the 7, the higher flap setting definitely adds drag allowing for a steeper approach without an increase in speed....helpful if the approach is a bit higher than optimal. What really stands out is how much higher the elevator stick force becomes to maintain the targeted rate of decent (no spring assist in my airplane).

It seems that your experiance is a rare occurance in the Kitfox (thankfully!) which make me wonder if there were several factors contributing in a rare combination such as:

1. Flap setting at 22 degrees above 80 mph...not recommended but if this were the only factor, I'm sure there would be many more similar reportings.

2. Forward CG...the IO 240 adds 100+ pounds to the nose of the airplane as compaired to the 900 series Rotax. Not sure where your CG is but if it's forward, it's not going to help the situation as the horizontal tail has to work that much harder to keep the nose up.

3. Forward wing sweep...the construction manual for the Series 7 (and I assume the 5) calls for a forward wing sweep with the heavier engines to move the center of lift slightly forward to help offset the extra weight in the nose. When I pull in 22 degrees of flaps, there is a pronounced shifting of the center of lift rearward requiring a significant increase in stick back pressure. Can you confirm if your airplane has the forward sweep?

Not sure if what you experianced was a tailplane stall or flap overspeed but based on the infrequent reporting of similar experiances in the Kitfox, I suspect yours may be the result of several combining factors including those listed above.

Thanks again for sharing your experiance with the rest of us and really glad it had a happy ending! :)

[n85ae]

A couple things:

I don't mind any comments that I exceeded the flap speed, I did BUT not
by a lot.

I have a fairly forward CG, but I also have a ballast box in the tail. I have
for an IO-240B Kitfox a decent CG, because I took the step to add ballast
in addition to the battery. Empty weight is 967

I have the forward wing sweep

My plane is a taildragger.

I almost always three point the plane, and have no issues with elevator
authority with 0-11 degrees flaperons. I don't have a gap seal on my tail
and I don't need it.

I never use 22 degrees for landing. I've only used 22 degree's when test
flying the plane, and normally do not like the feeling. Too much stick
force required, and the variable incidence tail is all the way at the end of
it's range which just makes me not comfortable.

This was the first time I ever used 22 degrees in a fairly steep fast descent

Just want to say one thing, so nobody gets the wrong idea. I was NOT
screaming down like a Stuka and pulling the dive Brake lever. I was just in
a "normal" steep descent. Which normally I'd pull the nose up and slip to
keep the speed from building too high. In this case I was "probably" just
past 80 mph indicated, and pulled in 22 degrees. I wasn't watching it that
closely.

I'm not a timid pilot, but I'm also not somebody who takes chances. I don't
do aerobatics in my Kitfox, or live on the edge trying to see just what I can
get away with in the plane. I've had spin training, but don't spin my plane,
etc. Just want to emphasize this was not during a Chuck Yeager moment
that it happened.

Even IF Chuck Yeager were in the plane, I seriously doubt he could have
reacted any faster than I did. He'd probably just have a lower heart rate
after recovery.

I feel that it's not likely what happened to me to reoccur with somebody
else, but IF it did and you were in the pattern. You would NOT recover
before you hit the ground. I would suggest that 22 degrees flaperon
position "might" be dangerous, and an unrecoverable upset may occur
with no warning.

So I'd say take this as a caution from me, as it did happen, AND in a
flight mode that could EASILY be recreated in the pattern. Like high
on final and a tad fast.

Regards,
Jeff

[t j]

I'v been wondering about this tumble since it was first posted. It seems to be the first, or first ever reported anyhow, so very rare. This airplane has balast in the tail to compensate for the extra weight in the nose. In other words, weight at the extreem ends of the longitudinal axis.

Weight at the extremes alters the moment of enertia. The moment for weight and balance purposes is calculated by multiplying arm times weight. Not readily apparant is that moment of enertia is arm squared times weight.

A small weight with a long arm can significantly alter the enertia.

When the flap handle is pulled up the nose pitches down which started the weights in the nose and the tail to swing around the center of gravity. Could the enertia been too much for the control surface...stab trim and elevator...to overcome?

The flap overspeed theory makes good sense to me. Maybe the extra weight at the extreme ends of the fuselage compounded the effect in this particular airplane???

[n85ae]

The IO-240B install already has the battery in the tail, I added 10 lb.s to
that. The plane did not pitch over when I applied the flaperons. It was
completely stable. It was shortly after I applied them (5+ seconds I'd
say).

So it wasn't that I applied flaperons and tumbled. I applied flaperons, and
was flying along stable and then wham it tumbled forward.

There was no warning, no wobbling, no twitchy stick, the nose just dropped
really suddenly.

Jeff

[SkyPirate]

Jeff,.. what took place ,..even if the plane is well balanced,..it would have still happened , flaperons,..ANY plane with flaperons,..kitfox..mini max..,, it doesnt matter,..( a full length control surface on the main wing)
because your pitch atitude and decent rate,..and I'll bet they were close to the same ,,..forward speed versus decent speed,..
you basically entered a downwind for a landing behind a larger plane ..the larger plane being your main wing the smaller plane the tail.
It's like I had said earlier if you fly back through an aerobatic manuevers wake ,..only you didnt fly through it,..your tail was flying in it,or not flying is a better example,.. until you cleaned up the disturbed air ,..which you did when you zero'd the flaperons,.. you had said you were worried about over stressing the plane when you pulled out ,.that indicated to me your decent speed was very close to your forward speed,..and when you lost the tail authority she actually went inverted ..( 2 G's inverted feels like a truck hit your butt pushing you up out of your seat)
As I mentioned before it's the same as doing a loop,..and you fly back through the wake,..with exception,.. with a loop you fly through the wake not with it,
with the flaperon at 22 degrees your main wing becomes the elevator if the tail is nulled,..you didnt stall the main wing ..you stalled the tail with your decent rate and disturbed air from the flaperons working together which hit the tail.
BUT ..you corrected it when you flattened the flaperons which cleaned up the disturbed air ,..which zeroed your elevator/main wing,..which gave control back to the tail,..so ..now ..what are we going to do for our next aerobatic manuever? ( and you said you didnt do aerobatics in your kitfox lol)

what was in your favor ,..altitude,..knowledge,.. and a spare pair of shorts ha ha

Chase

I'll add this ,..if you did the same thing in a conventional winged aircraft,..a cessna for example ,..and you gave any amount of aeleron during the tail stall,..the higher aeleron side will act like a brake,..the lowered aeleron side would give more authority to the flap on that side ,.the end result would be much worse,.

[BigJohn]

Jeff,

Excellent information on your part to possibly prevent someone else not coming out as fortunate as you. And the expert comments from others is very Valuable.

I don't believe that I read any where in the comments about your Elevator, i.e. the 5 which I fly and tail wheel has a smaller elevator than the 7 and by a significant amount, I early on noticed that I did not have what I thought was enough elevator authority is some situations expecially when I had possibly interupted or less air crossing the Horiz Stab. So Installed the Series 7 elevator on the 5 and it made a significant difference.

With you having more nose weight with your engine and your over all empty weight more than 150lbs heavier than my 5 and if you had the smaller elevator It is possible that with all the other factors just one more factor i.e. small elevator could have added to the issue. You may want to check on the larger elevator, like I said it made significant improvements on mine.

[n85ae]

I believe my Series 5 has the larger elevator, I think they switched over 1-2
years before mine was kitted.

However I'm not positive, I can measure it next time I go to the airport. What
are your dimensions?

[t j]

Okay, that makes my tail and nose weight enertia theory unlikely.

[SkyPirate]

thats a good find jlotty,. but with the cesnna's flaps being only part of the the control area,..not like the kitfox or any other flaperon plane. it being the complete control area,.. with the cessna,.. the flap vortices also make the nose pitch up due to the rotation of the vorticy,..right flap from the rear view counter clockwise ..left flap vorticy from the rear view clockwise,.. hitting the tail surface pushing it down,.. the larger vertical area helped with the adverse reaction of slipping/crossed controls at slower speeds ..at a higher speed the wash would engulf the whole tail nulling it out ,..hence the max speed for 30 degrees flap,..if exceeded which then makes the higher aeleron side work like a brake and the lower/down aeloron an added surface to the flap,.. what happens is now your plane will pull hard to the side the aeloron is up on until the tail swings out of the wash,..then it snaps back the other way violently,..the faster the forward speed the faster this reaction happens,..slower speeds can result in a flat spin
I'm no expert either ,..but aerodynamics are aerodynamics
it's a constant battle to have the favorable effect out weigh the negative even in life

Chase

[CDE2FLY]

Went flying tonight to explore the 22 degree flap dilemma:

Model 7, 914, CG middle of range, built in gap seals, fuel at 1/2 tank

Started at 10,000 feet and began a decent with 11 degrees of flaps. After I stabilized at 75 mph, pulled in 22 degrees and pushed the nose further down to build speed....80 mph....stabilized for 30 seconds....pushed nose further down....speed to 85 mph....stabilized for 30 seconds (1350 fpm decent) and recovered to level flight with 22 degrees of flaps still deployed. I had full control in pitch and roll although pitch forces through the stick were rather high.

I then tried forward slips in both directions with 22 degrees of flaps and 85 mph indicated. There was a slight buffeting through the stick but the slip was really extreme as was the rate of decent.

Although I wasn't sure what to expect, I do feel better knowing there doesn't appear to be any handling gremlins hiding in N725CE. :)

[n85ae]

I'm glad people are testing their planes, but be really carefull!

It might be related to my heavier motor, or the combination of that plus the
variable incidence tail. The 7 has the fixed tail I believe. Anyway I might just
have been lucky and hit the exact right combo.

My planes. getting a mechanical block for the 22 degree position this weekend
no matter what. I never needed the 22 degrees in 7-8 years flying the plane,
and one of the few times I ever used them this happened ...

Regards,
Jeff

[CDE2FLY]

Yes...I should have mentioned, mine is a fixed tail with manual trim. other Model 7s have the electronically adustible tail based on production date and/or selected options. As you indicate, the key will be to figure out what combination(s) result in what you experienced....I too would encourage a very careful approach to any flight testing. I stayed plenty high and had ahold of the flap handle the entire time just in case things started to go badly.

[Dorsal]

I have the variable tail and the spring and will very carefully repeat the tests CDE did.

[MotReklaw]

Thank you guys for posting your opinions and experiences. I'm sure there are many like me who are following your comments.