Crashed and Lost.

A minor note, the pressure is the same going upwind as downwind. The aircraft does not know the difference. Only the ground speed changes.

If the vertical stabilizer actually came off, I'd think you or the instructor could see it wobbling around. If it did, then you lose a lot of roll stability at the tail. However: for the plane to roll inverted and then not be able to "resume normal flight", I'd guess it stalled. Dr.1 Driver "There's a Hun in the sun!"

I have had weird effects flying in wind too.
On reflcetion these boild down to 3 or 4 basic categories
(i) Turbulence. Never had a plane flip upside down, but have had one go over to more than 90 degrees on many occasions.
(ii) gusting. A sudeden decrease in wind going upwind will cause a stall - pretty obvious. A sudden increase in wind going downwind is not so obvious - the plane is flying at the same apparent high speed, but just falls and flops and loses all control authority. This may be what happened to you.
(iii) wind shear. More normal IME at dawn or dusk, where laminar flow is likley and windspeed near teh ground is low. Basically an upwind approach may suddenly result in total loss of airspeed as you cross through moving air into still air. Tip stall and a pile in is the usual result if teh approach isn't fast enough.
(iv) severe up or down draught - basically like turblence, but more veertical. Your plane can lft 50 feet in seconds, or drop just as fast.
Flying is steady wind, is not teh problems. Groundspeed varuies but airspeed is constant and control is available. But varying wind speeds are very very hard to cope with - I am at best an 'intermediate' or 'advanced beginner' pilot. But I fly a lot on varying conditions, because thats what we have mostly, and around trees, and hedges, and I have had many many crashes due to wind conditions that at first sight looked like loss of control, but on reflection were to do with being tortally unable to judge the actual sirpseed under wildly fluctuating wind conditios, and even in one 'interesting' flight being almost unable from ground level to apprecaite how strong teh winds were 'up aloft'
Like finding my 'bad weather' plane - a Picojet that stalls at 18mph, and flies around 30 normally, hovering at 100 feet up...yet coming like an express train at ground level.
Like attempting a downwind roll in similar speed plane, and finding it took several seconds to complete, whereas coming back the other way it seemed normally fast. I conjecture a gust overtook it and it rolled at practically stall (air)speed only, because the next time I tried it it was fine...
Like having a rudder only parkflyer on its side at 20 feet, and being totally unable to get any roll authority via the rudder as it was basically stalled due to a gust from the rear side that flipped it...
Like having a plane snap its wings in calm conditions doing no manoeuvers at all. Bump? Ok the wing wasn't GREAT, but it had flown OK with it before.
I am not saying that you didn't have some other failure - but wind - especially turbulent wind - is bloody funny stuff.

Hmm... I hadn't thought of that. Would a possible scenario be that while flying slowly with the wind, a gust could've come behind it and caused it to flip and lose all stability?
-Nick

Yes, see my post.

This theory makes the most sense of all the scenarios we came up with. If the wind caught up behind it and neutralized the relative wind, there was nothing to hold the plane up and it just flopped out. Everything seems to be making sense now.
I didn't think the rudder actually came off and as DR1 said we'd probably see if flopping around. The plane was behaving so erratically that I couldn't imagine what airfoil or control surface malfunction could've caused something like that.
The worst part of all this is we were about to pack up and I was like c'mon, just one more flight.....DOH!
Thanks a lot guys!
-Nick

We had a guy who lost a plane a couple of weeks ago in an orchard that borders our field. It was during a giant scale fly in and there was another guy there who was demonstrating powered parachutes. He flew over the orchard and found the plane. It was out considerably farther than all of the people who watched it go on thought. Good Luck Bill

I did see it, and it made a lot of sense. Sorry about the poor timing. I post and view groups at work so sometimes I'll type something up, then get interrupted, then a couple hours later proofread and send....
-Nick

I have an LT-40 and thought when reading the assembly instructions the vertical tail feather wouldn't have much support so I added a thick bead of epoxy between it's sides and the fuselage.
Maybe your's came part-way loose and the pushrod held it at a cocked angle hence the roll. Anyway it should still be floating around out there in the marsh somewhere. Maybe somebody has a camera ship.
Prop Flipper

I've actually got a wireless color video cam that boasts 1000ft LOS. I'm thinking if I can get someone willing to mount it on a big slow flying aircraft, and find some magical and inexpensive way to get a tv with a video input out in the field, I can probably find it. It's just when you're in those weeds it's damn near impossible to see 5 feet from you. My next plane (if I don't find this one) will have a recovery system.
-Nick

Absolutely. If your ground speed is 30 mph, and the wind speed (also measured over ground) in the same direction is 20 mph, then your plane is only seeing 10 mph over the wing; possibly too slow to generate enough lift. Dr.1 Driver "There's a Hun in the sun!"

In a stall; the ailerons go first, closely followed by the elevator, and lastly, the rudder. Another indication of an empending stall is the tail "wagging." Dr.1 Driver "There's a Hun in the sun!"

Yea word. I noticed it was coming a bit loose and actually had some materials I was going to use to reinforce it. But I didn't have a chance to do it and it didn't seem unusably weak, just like it would get worse if I let it go without doing anything.
I'm really leaning towards the possibility of this being caused by winds though, I don't think I could've gotten that trainer to flip that fast if I tried!
-Nick

Nick:
If at all possible find a way to search for your plane that lt-40 is a tough bird and you will probably find it pretty much intact going by your discretion of the crash. I had one that took 9 crashes to kill (not all by myself) and at least 3 were near to straight in. The one that killed it was when the elevator decided it no longer desired to be a part of the group effort and with the failure of 4 ca hinges went its own way. Managed to get it into some resemblance of a flat spin to slow it down, but the rough ground broke the fuse in half. Oh no complaint on the hinges two broke dead center the other two took wood with them. Oh my vote sounds like a stall to me. Been there done that.
Happy hunting if the balsa gods stole it build another just like it, have fun
tomb

Lost the vertical fin on a Super Stunts 60 while coming out of a power dive. Ripped that sucker clean off the fuse. Plane immediately rolled over on its back and headed behind the flight line. I managed to direct it back in front of the flightline but it ended up hitting the ground. Guess my answer would be yes, I believe losing the fin can cause the plane to roll overe and die. Mine was repairable tho!

Yes... :(
Dave

Kno the feeling...:(
My crashes/accidents/dings/breaks/thumps/smashes have ALL been on the "last flight of the day"
Hmmm... I think there is a pattern here...
Dave

It always is. It might hve been a failing receiver battery too? Flying in wind, those servos keep on working nearly all the time..

I've lost a plane, too, where I couldn't figure out what happened.
My big mistake, I think, was letting the wind blow it too far away from me and then taking my eyes off of it to watch a helicopter buzz the flight line. I was loafing around at half-throttle. When I looked back, the plane was in a spiral dive. :o(
I carry a compass in my field box to help with searches. I used it to march in a grid pattern through some very difficult woods and find a friend's plane that had been lost for three days.
The compass made me go into a thicket that I otherwise would have skirted. That's where the plane was, nose down. I didn't see it until I was about four feet away from it, ready to walk past it.
In Syracuse, the STARS have a magnificent system to guide searches in the swamp. The searchers get a tall flag and a walkie-talkie. The guide tells them where to search. We found a Zagi in the swamp following their directions.
It takes practice to learn the relationship between seeing an airplane go down and knowing how far to walk to reach that point. Go farther away than you think you should. You may yet find your plane with re-usable parts intact.
Sorry to hear about the loss in any case.
Marty