Mystery of the ill-fated Texan solved  
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All Forums >> RC Airplanes >> RC Warbirds and Warplanes >> Mystery of the ill-fated Texan solved
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Mystery of the ill-fated Texan solved - 6/25/2005 4:29:09 AM   
2slow2matter


 

Posts: 2399
Joined: 8/25/2004
From: Springtown, TX, USA
Status: offline 		While building an arf today, I decided to use some servos from the Texan that didn't make it through the maiden (you guys might remember the thread). Anyway, I had pulled the servos out of the Texan Fuse to make rebuilding easier, so these servos were handy. I put the servo off of the Texan rudder on the throttle of the new arf, and noticed that it wasn't working properly. Upon further inspection, I noticed it was stripped. This would explain why the plane did what it did. While lifting off, it started to veer ever so slightly to the right, and I applied just a touch of elevator, and maybe a touch of rudder to correct course. The plane at that time dipped the left wing and the tail came up and over, and it went straight in. A stripped rudder servo could account for all of this. I'm still very inexperienced at warbirds, but I now feel like I have an answer to my problem (doesn't help much, except mentally!) Before it goes up again, it will have hight torque, metal gear servos for the elevator and rudder!!!

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RE: Mystery of the ill-fated Texan solved - 6/25/2005 6:39:21 AM   
BobH


 

Posts: 4420
Joined: 4/1/2003
From: Springfield, VA,
Status: online 		Not to dash your discovery but the servo could have been stripped as a result of the crash. This is a not to uncommon thing.

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BobH.

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RE: Mystery of the ill-fated Texan solved - 6/25/2005 6:50:47 AM   
mugenkidd



Posts: 1498
Joined: 11/28/2002
From: Oklahoma City, OK, USA
Status: offline 		I have to agree with bobh, with stripped rudder servo I don't see how you could have gotten the Texan off of the ground, unless it broke on take off. But even then if the servo was stripped then it would be stuck in one position and it seem like at lift off you had the rudder nuetral then added imput. To me it just sounds like the classic stall-snap-and crash which warbirds are notorious for.

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RE: Mystery of the ill-fated Texan solved - 6/25/2005 2:25:18 PM   
Mustang Man-RCU



Posts: 179
Joined: 4/7/2003
From: Moore, OK, USA
Status: offline 		Yep. I gotta agree with BobH and Mugenkidd 100%. Applying up elevator before sufficient ground speed is attained is one of the best ways I know of to initiate a stall/snap on take-off,particularly with a warbird.

Steve

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RE: Mystery of the ill-fated Texan solved - 6/25/2005 3:57:23 PM   
270win


 

Posts: 858
Joined: 1/12/2005
From: Lawrenceville, GA, USA
Status: offline 		I've had servos fail just like 2 slow describes... It happened this week as a matter of fact. It was a retract servo that was working flawlessly. Then all of the sudden it would move to retract the gear, but not to extend it... This is on an air system so there's very little torque needed in either direction. Some of the gears were stripped....

At low speed and high angle of attack (i.e. just after takeoff) the rudder going full deflection getting stuck could cause a wing to drop..... the problem is that it sounds like the tail stalled... that would explain the way the nose tucked in.... The question is why, usually the wing stalls before the tail does.... I don't know. It's not impossible that a servo failure was a major contributor to the crash... JMHO

270

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RE: Mystery of the ill-fated Texan solved - 6/25/2005 5:28:24 PM   
scalebldr


 

Posts: 541
Joined: 11/8/2002
From: allenstown, NH, USA
Status: offline 		while the stripped servo,which could have happened on the takeoff run,could have started the model to veer off course at liftoff,the cause of the stall and crash was the result of adding the up elevator at too slow a speed should have been down elevator to stop the climp build airspeed the try to level the wings or adjust course.

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RE: Mystery of the ill-fated Texan solved - 6/25/2005 5:40:08 PM   
Mustang Man-RCU



Posts: 179
Joined: 4/7/2003
From: Moore, OK, USA
Status: offline 		I think thats what I said

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RE: Mystery of the ill-fated Texan solved - 6/25/2005 9:55:57 PM   
paladin


 

Posts: 1658
Joined: 2/13/2002
From: Vestal, NY, USA
Status: offline 		2slow, You need to check the rest of the servo's for stripped gears also. Slowly move the servo through its TX movement while holding the output arm between you finger lightly resisting the servo movement. If you have a stripped servo at somepoint the motor will start to spin.

Joe

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RE: Mystery of the ill-fated Texan solved - 6/25/2005 10:30:09 PM   
2slow2matter


 

Posts: 2399
Joined: 8/25/2004
From: Springtown, TX, USA
Status: offline 		Joe,
thanks.
I checked all of them very thoroughly. In fact, the rest of them flew today on maiden of a 40 sized stick. No problems. I replaced the gear set in that servo, and it's now destined to be on a throttle somewhere. It is likely that the rudder servo stripped while taxiing, and on the take off roll, or it could have stripped on the crash--it sure explains why the tail came up and over, though--wouldn't you think? Almost like a low (very low) altitude stall turn. Anyway, Never the less, I still have repair work to do.
I just purchased a 90 inch PT 19 ready to fly with 42 CC gasser. It hasn't been flown in a while, so I'm going through it right now--replacing pushrods, servo extensions, battery, stuff like that. Checking all of the joints. Then, I have a guy lined up to help me learn how to fly it. I figure it will be a good transition from sport to scale, maybe. Plus, I like the looks of it, and I practically stole it.

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RE: Mystery of the ill-fated Texan solved - 6/27/2005 1:29:09 PM   
SpitfireMKI



Posts: 1463
Joined: 7/6/2002
From: RAF Turnhouse 603 Squadron, MD, USA
Status: offline 		The description of your crash is still a picture perfect example of stalling a plane on takeoff. As you described, it looked like a stall turn close to the ground. As I stated before, I watched a guy cream a byron T-6 in the exact same manner. The T-6 is a tricky plane to fly especially for a beginner.

Forget about that servo theory, if the plane cartwheeled that would kill the gears.

I myself had a good wake up call this weekend, I got the chance to fly a Bates Dewotine D520 with a ZDZ 80 and a three blade prop. As careful as I am and as gently as I could advance the throttle, I still had trouble flying the tail as it wanted to nose over, then add in the torque swing from the gobs of power and I was rewarded with a shaky take off. Don't get me wrong, I was not all over the field or in any danger of destroying the plane, it just did not handle as I expected. I think much of it had to do with the three blade prop and the very sensitive throttle. I'm not use to that kind of set up.

The flight was no good as the gear would not stay retracted.

The landing was pretty crappy too, dealing with a hot gusty crosswind at our field is tough, we get some real turbulence at the threshold. Add in the very sensitive throttle and a idle that jumped up on me during the flight and the landing was not smooth.

From these mistakes I learn from.......

a) I needed to slow down, I broke my own rule of proceeding too fast. There is no hurry to do anything.
b) More taxi time and a few dry runs would have gotten me use to the handling characteristics.
c) As I have learned previously, with the wind conditions present, I should come in a little higher and hotter, flatten out and let theflaps slow her down.
d) If the idle is too high, go around.
e) Always trust your own intuition.

So lessons learned. If this hobby did not teach me something new everyday, I'd go play golf. (I hate golf)

Did you get a cub ?

S1

< Message edited by SpitfireMKI -- 6/27/2005 1:40:25 PM >

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RE: Mystery of the ill-fated Texan solved - 6/27/2005 3:24:37 PM   
ccostant



Posts: 163
Joined: 1/3/2004
From: Hopkinton, MA, USA
Status: offline 		SpitfireMKI is absolutely right on with regards to the T-6. I have a Midwest AT-6 that's on the heavy side and it is a handfull on takeoff. It exhibits all of the bad behavior described. Without enough ground speed and a shallow climb out, it will stall every time. I consider myself a very experienced flyer and this plane still presents a major challenge on every take off. The good news is it handles well in normal flight and landings.

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       Post #: 11

RE: Mystery of the ill-fated Texan solved - 6/27/2005 8:39:51 PM   
paladin


 

Posts: 1658
Joined: 2/13/2002
From: Vestal, NY, USA
Status: offline 		2slow, does your PT-19 have flaps?

With a gasser you will need to carry throttle right to the ground because the gasser can idle much lower than the alcohol engines so it presents more disk. Disk refers to the disk the prop spins in but the real important thing to remember is a slowly spinning prop causes tones of drag and will slow you down fast. I fly mostly glow or ZDZ because they are light. I do have a Dynaflite PT-19 with a Zenoah G38 in it. Fly’s great. But every time I fly gas I have to remember to carry throttle. Looks with a heavy gasser are quit different than you will be used to mine look more like figure D’s if I kill the throttle where I expect to with a modeling engine.

Joe


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RE: Mystery of the ill-fated Texan solved - 6/28/2005 2:15:55 PM   
SpitfireMKI



Posts: 1463
Joined: 7/6/2002
From: RAF Turnhouse 603 Squadron, MD, USA
Status: offline 		2slow, the PT will be great, kind of a low wing cub. You will still need to fly it off and back on.

Though Paladin has a point with the idle on a gasser, first you must always fly the plane for what it wants to do, not what it's supposed to do. An example is my TF Mustang, it likes power cut to idle as it crosses the threshold, my P-47 and P-40 want a click of power held till the flair, all are gas. Prop size and pitch will also add variables.

S1

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All failure, We learn from.... Discovery"

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RE: Mystery of the ill-fated Texan solved - 6/28/2005 2:24:53 PM   
2slow2matter


 

Posts: 2399
Joined: 8/25/2004
From: Springtown, TX, USA
Status: offline 		Spit, and Paladin
Well, as I said before, the Texan never cartwheeled, just nosed in. Very possibly my fault--I'm going to have plenty of lessons before I fly it again.
No, I did not get a cub. I had an opportunity to buy this dynoflite PT 19 already built and ready to go for a steal of a price, so I jumped on it. I got it for about 3/4 of what it would have cost me to buy a cub ARF, engine, and radio gear. I thoutht it would be a good warbird trainer for me, and I absolutely love the way it looks. It worked out really good, because the guy who sold it to me (for a friend's estate) has actually flown the plane before, and has years and years of experience (decades) behind the stick, so he's training me on it. We flew it twice Sunday. He took off, and I flew it in the air, and he landed it. It'll be this way for a few more trips, then I'll ease into takeoffs and eventually land it. It's like I'm learning all over again. Kind of funny to see someone hand off the transmitter on one plane, then go get a sport model out of the trailer and tear up the skies. However, it was nice to bring the big bird back home in one piece, so that's how it will be until I'm comfortable that I can fly it by myself!
It doesn't have flaps. I wish it did, and this winter I may retrofit some split flaps, I haven't decided yet. My instructor hasn't flown it in quite a while, and the sink rate on it really surprised him at first. You are absolutely correct about the landing issue, Joe! The second time around he landed it at right around 20% or so throttle, and it was much nicer looking!
This plane is huge, and beautiful on the ground and in the air. So graceful. I just love it. I probably won't even touch my Texan now until this winter!

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From a pile of sticks they are born, to a pile of sticks shall they return.

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RE: Mystery of the ill-fated Texan solved - 6/28/2005 4:31:46 PM   
SpitfireMKI



Posts: 1463
Joined: 7/6/2002
From: RAF Turnhouse 603 Squadron, MD, USA
Status: offline 		You're on the right path, good luck and have fun..............

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"What madness ? What secrets ? We Plunder,
All failure, We learn from.... Discovery"

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