2slow2matter

My Feedback: (1)

OK guys, help me figure this one out. First, as stated before, this was my first warbird. I have flown my dad's .40 sized Corsair, and it was a handful to take off and land, but I was able to do it. The landing of it would have been flawless, except that it rolled off the end of the runway, and onto the rough grass and nosed over. So, I felt comfortable flying this big T-6 that I had built. Well, after warming up on a big stick, I was set and ready to go. Everything was balanced per the manual, and looked trimmed on the ground. I lined up, and starting forward with the throttle. It was tracking straight down the grass runway. I kept increasing power. The tail came up--pretty. Rolling on the mains, and gaining speed, it lifted off on it's own--no elevator input from me. Once airborne, it started to drift a little to the right. By this point, I believe I was at full power (saito 100 swinging a 14 X 8 prop). I began to give a little elevator. I tried to be careful of elevator input early in flight because I know these things can snap. Well, with what seemed to be little elevator at all, the left wing dropped, the tail came up over the top, and the thing went into the ground at full throttle, nose first, from about 10 feet or less). It happened so fast. Things went from so pretty, to so ugly so fast that I was numb. I'm thinking that it may have snapped, but why? It had enough airspeed to lift off on it's own, and I didnt' think I gave it that much elevator. What did I do wrong? Hopefully someone can shed some light because I'm going to rebuild this thing (only the nose was hurt--nothing else) and try it again. I would like better results next time. The build was good. I feel comfortable in the build process. I'm pretty sure this was pilot error, but what error? I wasn't using flaps.
Help, please. Thanks..

captjack

My Feedback: (3)

sounds like the plane stalled and snap rolled on you.unless there is a trim problem,which there could be on a new plane.the drobbing of a wing tip is the first sign of a plane stalling.I would check the wing and stab incidenes to see if they are the same,also i usually balance new scale planes at the forward cg limit so it is a bit nose heavy.If this plane lifted on it's own does not mean that it had attained flying speed.should have leveled off first to let the speed build before starting your climb,I know hindsight is 20/20 but a stall can happen at any attitude and at any speed.high speed stall is just what it sound like.a stall at high speed caused by a large surface deflection very quickly causing a sudden change of airplane attitude resulting in a high speed stall and snap.

Sturtz

My Feedback: (20)

Not that you made this mistake,,, but the last time I saw a warbird maiden death the way you discribed ...... the guy was of course,,, nervous and excited. Long hours of detailed work . Ailerons were reversed.

the-plumber

The bit about

is a little bothersome.

If it had been a stall you would normally have seen the left wing droop and the tail tuck under, after which the model would normally flop over on it's back, and you know the rest.

Your description sounds more like the elevator servo was reversed.

Everyone knows CATS : controls, antenna, trims, switches.

It's the 'controls' part that sometimes bites ankles on flight tests.

For 'controls', use a mantra :

Roll right, raise right not left,
Right turn, right side,
Pull up, pop up,
Push for noise.

Pretty self-explanatory.

I've seen big name "flyers" launch finely built scale models at Scale Masters Qualifiers with ailerons reversed because they were in a hurry and didn't take time to do the "C" in CATS.

grbaker

My Feedback: (29)

That's the first thing I thought of also.

2slow2matter

My Feedback: (1)

Thanks for the tips. I just checked the elevator servo, and it was not reversed. Pulling back on the stick causes the elevator to deflect upward. I know it's weird that the tail came up and over. That's what has me so perplexed. I was hoping that someone had seen this before and could enlighten me. maybe it wasn't ready to fly yet (speed wise), but as mentioned before, usually snaps end up with a wing dropping followed by the tail. This plane should be fairly gentle to fly. My plane weighed in the neighborhood of 10 pounds. Between 9 and 10. It was 9.5 before I added 6 oz of weight to the nose. The saito 100 shouldn't have a problem flying it, and that is a lot of wing surface (70 inches). However, it does taper, and I'm not used to a polyhedral wing yet. Keep em rolling. I need to figure out what went wrong so I don't have a repeat performance! I know there will be a lot of growing pains in learning to fly warbirds, and I can handle it. This one was a tough pill to swallow (mainly pride, since the plane is relatively easy to fix). One good thing about it--now I know I can beef up the front end quite a bit and still be within the balance points!

the-plumber

Hhhmmm . . .

Presuming the CG didn't shift and the other controls are as they should be, I'd look at the firewall and engine mount. Might be the firewall pulled loose or the motor came loose from the mount, allowing the thrust line to shift down.

OTOH rebuild the thing and try again. Do make sure the control throws are per the book and that you don't have excessive travel volume. Also do a thorough range check with the engine at full tilt.

2slow2matter

My Feedback: (1)

Plumber, thanks

I wondered if some of the stick on weights that I added to the nose might have come loose on me, and cause the CG to shift. However, even without those weights it was still within the recommended. Who knows... I had only added the stick ons for temp, and was going to epoxy them in when I found the CG that I really wanted. I wondered about the firewall coming loose as well, but I didn't hear any pop or other noises before the incident. Still could have happened, I suppose! I did a range check, but not with the engine running. I should have, but I didn't have anyone else to help hold the model while I walked away. I didn't have any teather, either. Well, it will be rebuilt. I just looked at it. Looks like a new firewall, rebuild the forward crutch some, a little work to the forward wing saddle, and a new F-1 ring which can all be rebuilt with the plans. Just sucks that after all of this time, I'm not flying it RIGHT NOW! I really didn't like how the firewall was held on by those stringers anyway. That could have been a cause of defect. I had beefed it up by adding epoxy and balsa around the firewall, but that only secured it to the sheeting. On the rebuild, I think I'll use a little larger stringer, and then glass the firewall in after I'm done. And, the firewall will probably be about double the thickness

Blue_Moon_

build........rebuild........build........rebuild.. .....build......rebuild----will the insanity ever end?

rifraff

My Feedback: (1)

sorry to hear about your plane

It sounds like it stalled.. wich way was the wind coming from .did you take off towards or away from the wind
if you want a nice warbird that handles like a trainer get the modeltech p47 or the great planes JU-87 Stuka,they both handle very nice and can use that saito 100 you have
good luck and happy flying

E Henry

I maidened my top flight Texan about a month ago. I am still new to warbirds and trying to figure them out. I am using a ST .75 and I kept the plane light (no retracts, etc.) I just wanted a Sunday flier the would give me no problems. On the first flight I applied throttle slowley and did my best to keep it going striaght. At about 1/2 throttle the plane start to lift off the ground and I knew I did not have enough air speed. I gave it full throttle and was able to pull it thru. After flying it I noticed the trim was pretty close but was unsure why it lifted so quickley. Since I have gotten the hang of taking this plane off I apply just a small amount of down pressure on the stick and it keeps the plane on the ground until I I am sure there is enough speed. This is a very fun plane to fly and landing could not be any easier. good luck with your rebuild Erik

captjack

My Feedback: (3)

Ehenry,
have you checked the incidence of the wing and stab?if so what were they.if the wing has more incidence than the stab it will want to lift off before it should.

E Henry

CaptJack, No I have not checked the incedence. The plane flies very good. If the incedence were off enough to make the plane lift off early, wouldn't it need a fair amount of down trim for level flight? The plane only required minor trim adjustment for level flight. Like I said I am new to warbirds and still learing. If the incedence is off, what changes can be made to correct? Thanks for your addvice

Cyclic Hardover

My Feedback: (3)

I have a fw warbirds and manyof my buddies also from the little ones up to the big ones. Warbirds are not forgiving. With those short noses and moments its easy to get one tail heavy and thats all she wrote. Your theory on the weight coming loose could have happened on take off and immediately going tail heavy after lifting off is very possible. I saw a guy once try and land a giant scale P 51 that was tail heavy he was all over the place and finally pancaked it on the runway just to get it over with.

From everything I have ever done or seen, warbirds need speed and a shallow liftoff. If you just pull it up off the ground , it can flip on you.
You know how you see guys landing with some stick or something and they have these high bounces, then decide to rap on the throttle and go around and try again? Can't do that on a warbird or again , it will flip.

2slow2matter

My Feedback: (1)

E-Henry,
It is quite possible that my pre-flight ground trimming set the elvator too much on the positive side. This would have made it lift off too early. who knows. I'm sure of two things--it crashed, and it will be rebuilt in 10-15 hours worth or work. When I try it again, I will most likely make it nose heavy by at least 1/4 inch or so, and set a little down elevator in the trim before takeoff. That way it won't lift off until I'm sure it has enough airspeed. I did not check the incidences on my bird either. All of that was set by the die cut ply pieces, and should have been right. Maybe I shouldn't have taken it for granted. I have a meter at my disposal, and I'll check it before it flies again.

paladin

My Feedback: (9)

2slow, I’m sorry to hear about your problems. It sure sounds like a snap. My first concern is that you pulled E. If it lifted off by its self, off grass I would think you would be pushing E. My reasoning is this, when you hold elevator the plane should loop But you say you were adding elevator. That tells me that when your angle of attack should have been increasing, because the extra trim that made it lift off out of grass with out you rotating it is still there, the angle of attack was decreasing. So I’d bet that at takeoff the wing reached a angle of attack that with that power setting could not sustain air speed and began to slow down, that is why the plane started to loose angle of attack. Making you think it needed elevator. As it lost speed it dropped a wing panel changing its angle of attack That was your warning, you needed to poke the nose down. When you fed in up E you completed the stall.

For takeoff next time you want to add enough down elevator trim so that you have to rotate it yourself ( I’d go with six clicks of down E). On the next takeoff role once you rotate keep the plane as shallow as possible. That means you will have to let up on the E after rotation, once the wheels clear the grass. The shallower the climb out the faster the plans will gain speed.

Now while you are rebuilding the front move the throttle servo and Rx pack under the cowl and you can remove that nose wt and reduce your total flying wt. If you want to know how I can tell you.

Joe

DiscoWings

My Feedback: (76)

well ya.. thats pretty much right.. buildings kits is hella pain...specially when they get smoked.
stick to arfs, won't hurt as much.[:'(]

2slow2matter

My Feedback: (1)

Joe, I will definitely trim the elevator down for the next flight, so that I have to rotate it myself! I'd really like to see some pics of how you put the servos and batterypack up front. that would defintely help my situation out! All of this happened within 5 feet of altitude, so I didn't have a chance to correct. Rudder might have helped my situation some, but I didn't think that fast. Pilot error for sure. I'll rebuild it within the next couple of weeks and give it another go. Thanks for all of your help!
One thing that really surprised me in the short ordeal was the fact that the plane tracked straight down the runway, with no rudder input. I gradually fed in throttle, and it was like the thing was on rails! And, not even a hint of nose over. I was more worried about nosing over than anything. Once the wheels left the grass, I thought I had it made. Especially since it flew for a second or so before I began to add E. Then, all hell broke loose--and that fast!

paladin

My Feedback: (9)

2slow, I have a very good friend here that decided after watching me do this for many years he would give it a try (warbirds that is). He bought a H9 P-51D and we added flaps. At first he could not understand why I said to replace the factory retracts. Then one day Prior to landing with flaps he found out why. He was on a landing approach and I was taping it and about when He had it timed to hit the runway he yanked the E to unload the gear for the landing (other wise they would bend back and he would nose in. Well the plane climbed off my video screen then landed inverted. He was real lucky the plane was not damaged at all. My point is I always here that Warbirds are hard to fly, It has been my experience they have improved my flying! By that I mean prior to flying Warbirds I did not know the limits of flying a wing because everything I had was overpowered. I’d have been much happier if your T-6 was closer in wt to mine (8.5#), that extra 1.5# makes a big difference in how the plane handles. It forces more reliance on flying the wing when most new modelers only know the point and shoot of being over powered.

Rule number one for you now DO NOT USE THE RUDDER CLOSE TO THE GROUND!!! I know you here people all the time talk about using rudder on Warbird takeoffs and landings. I don’t know what you’ve flown before but I do know that most warbirds add a bit of down elevator and if you are not used to it the ensuing up E is much more dangerous. Get to know the plane and how the rudder affects it before attempting rudder correction after lift off.

I told you the ground handling was good. The only thing you may see is it going on to one wheel once it gets close to flying speed. For that the answer is to rotate because the plane wants to yaw.

Don’t worry about pilot error. Every crash I’ve had has been pilot error or maintenance error, and both guys are me and I reserve the right to be wrong ant any time with out warning. Although I am amazed by the guys that claim radio interference when they really stalled the plane. I belong to the Binghamton aero’s and they have a maneuver I like to call the popsicle takeoff (and landing). In short the plane rotates and climbs out with ever increasing angle of attack and at some point snaps and augers in. While spinning in the pilot yells “I’m being hit!� Once landed (being generous) The pilot turns insisting to check every radio at the site immediately! There is also a variation called the dead battery dive, no explanation needed.

To put the throttle servo on the engine mount there are two ways. Dig around the shop for one of those Aileron boxes:
http://www2.towerhobbies.com/cgi-bin...?&I=LX0869&P=7
http://www2.towerhobbies.com/cgi-bin...?&I=LXH380&P=7
Screw it directly to the engine mount then install the servo in the box.

The second method requires that you buy some PFM:
http://groups.msn.com/impscale/artic...to&PhotoID=206
The last time I bought this stuff (2003) it was 9.99 with 10.00 shipping but it is worth its weight in gold. It is a glue that is nitro proof and protects against vibration damage. To attach the servo with this stuff put some on the servo then press it in place on the engine mount holding it there with a “C� clamp over night. In the morning nothing short of a #29 x-acto knife blade will remove it. I have picks of servos mounted this way here:
http://www.rcuniverse.com/forum/m_21..._5/key_/tm.htm

A number of craft stores sell an adhesive called R6000 which is very similar out of the tube but does not hold up.

When you put the firewall in put a box on it to hold the batteries made of 1/8 LT PLY. You probably have a flat pack and that may not fit under the cowl. When I needed mine under the cowl it was a square pack, it you need help making a flat into a square let me know it’s a peace of cake. This box will require removing some of the false firewall with a dremel. Once the box fits in place on the firewall between the balsa fuse skin and engine mount put a hole in the firewall in one corner of the box big enough to fit the connector through. Then glue the box to the firewall, my box was open towards the prop.. The hatch can simply screwed in place.

If you need any more detail let me know.

Joe

Gremlin Castle

My Feedback: (14)

There is a lot of good advice in your post but not using the rudder close to the ground is advice that most heavy iron warbird flyers would not agree with.
Using just the ailerons as the sole directional control device during and just after takeoff has put many plane in the dirt.
One of the most common mistakes is using the ailerons to bank away from the direction the nose heads when the airplane breaks ground in a cross wind. The variation on the theme is horsing the airplane into the air green because directional control is being lost on the ground. The airplane pops up off of the ground effect and either digs in a wing tip or gets completely over on its back.
People are always surprised to see the wing suddenly rotate against the up aileron and roll over in the direction they were attempting to turn away from.
I fly a number of heavy warbirds that go right to the 55# limit and rudder is an essential part of the roll and directional control on both the climb out and the landing approach.
I also fly giant scale aerobatic ships and even though they are pretty much decoupled on the yaw and pitch axis, the rudder is still the only reliable and safe control for pointing the nose during takeoff.

As for down elevator that is situational to the particular plane and the surface that it is flying from.

I have a 55# Bearcat that requires no elevator input for takeoff while thy Y/A P-47 requires up at the beginning of the roll followed by down to raise the tail and neutral for the climb out. The Siewert KI-84 will raise its tail with no down elevator but takes a slight amount of up to rotate it for takeoff.

[quote]ORIGINAL: paladi

Rule number one for you now DO NOT USE THE RUDDER CLOSE TO THE GROUND!!! I know you here people all the time talk about using rudder on Warbird takeoffs and landings. I don’t know what you’ve flown before but I do know that most warbirds add a bit of down elevator and if you are not used to it the ensuing up E is much more dangerous. Get to know the plane and how the rudder affects it before attempting rudder correction after lift off.

paladin

My Feedback: (9)

Gremlin, Using rudder to keep the plane tracking straight on the runway is fine. As he adds rudder the E coupling will keep it on the ground and have to be overcome by the E at rotation. I prefer to us lift vectoring over rudder for directional control once air born. Now the way I was taught to lift vector you hold aileron into the wind and use the rudder for directional control on the ground. If done correctly the down wind wheel will lift before the up wind one as the plane lifts off banked into the wind.

Now he is flying a plane for the second time that will not be trimmed. It has already shown the stability I’ve experienced with mine. He’s just trying to get it trimmed. I’m sure he’s not going to be flying in winds over 15mph and trying to get it down the runway for the initial flight. So with this knowledge I feel the amount of rudder he will need after takeoff will be minimal compared to the risk which the E management posses. I’ld want him concentrating on a smooth rotation and shallow climb out to allow the plane to gain speed. The added E coupling when rudder is used after lift off will only complicate his E management on the takeoff.

For those who are wondering fly your War bird straight and level down the center of the runway add lots of rudder and hold it. Notice what the plane does. In addition to the intended yaw, it will bank, and the nose will drop. This tendency is called control coupling when you add rudder you also get unintended aileron and elevator coupling, specially in warbirds.

Joe

SpitfireMKI

My Feedback: (2)

Any warbird pilot who says not to use the rudder to correct yaw at anytime should hang up his helmet and goggles now. Arrrrrrrgggghhhh !


Flying an aircraft especially a model warbird, requires use of all controls (Throttle,rudder, elevator, aileron) - period

This T-6 take off is a classic example of taking off too soon-a result of an inexperienced pilot - period.

You must fly the airplane at all times not the other way around - period.

The tail going up and over was just part of the tip stall.

I will join those above and reiterate the correct advice already provided:

You must ' fly ' the tail off the ground, this is a balancing act of the elevator to keep it from pitching nose down as well as pitching nose up.

In addition, you are managing throttle and RUDDER to maintain your heading. The pitch coupling that comes from the rudder will hardly be noticed due to a) there is not much airspeed yet and b) if you are flying the tail properly you will be taking it out without really noticing it. Once heading is set, tail is up and flying, you should be able to accelerate the plane to get to airborne. Once you break ground, you should maintain a realtivley shallow angle of climb as airspeed increases. Watch those ailerons, never ever use the ailerons to correct yaw, especially on a warbird. You only correct roll with them. There is a fantastic video of a huge T-6 in Paris crashing after a landing bounce, the pilot lost airspeed and tried to power up and then correct the yaw to the left with aileron. You can see the aileron inputs to the right and she tip stalls hard left. The down going aileron (Left side in a right roll input) increase that wings angle of attack and the wing stalls to that side first.

I sat helpless as an inexperienced self proclaimed ' warbird ' pilot trashed a big T-6 at our field doing exactly what happened here.

My advice, (Even if you don't want it) is this:

Since you are already flying, get a 40-60 size Cub. The cub will teach you how to use all the controls. A cub is very easy to fly but very, very difficult to fly properly. Fly it till you can do take-off and landings in your sleep, that's using ALL CONTROLS and maintaining a straight line, shallow climb outs, and no big bouncers on touch down, then get the AT-6 out.

The AT-6 is really a lousy first warbird (IMO) especially one like a TF that has more scale lines, it swings hard on take-off, has a nasty tendency to tip stall (wing design no doubt) and landings will bounce more often then not, this will result in a classic tip stall if you bounce to high and kill the airspeed. I have always heard that if a cadet pilot could handle the full size AT-6 then a Mustang was cake. That is absoutely true in models. For an experienced r/c warbird pilot, the T-6 will be a delightful challenge to handle, but as in this case, for a novice, a busted airplane.

I too, flew a corsair before an AT-6, that corsair was a breeze compared to the t-6. The T-6 (mine was a Harvard) was wonderful to fly once I got use to it's traits. Still, a challenge getting off and on the tarmac.

Sorry to be harsh.

S1

Ruudje

I also build and flew the TF AT6 some years ago. I sold it because it was a pain in the ass during landings and take off.... I had the CG and throws according to plans. After I sold it I spoke a guy that build and flew most of the TF kits. He told me that he shifted the CG of all of the TF kits about 1/2" forward because they all flew very tailheavy. Your story sounds like a tailheavy plain.

After the AT6 I build the TF P51D. I have the CG 1/2" forward to that reccomended on the plans and it flys great!

I wish you luck!

SCALECRAFT

My Feedback: (13)

I don't know if this was asked ,but what did the model weigh, CG'ed.

paladin

My Feedback: (9)

2slow, I’ll pm you this has degraded into name calling and I’m not going to play that game. If you are interested PM me back and we can swop e-mail addresses.