MetallicaJunkie

http://www.youtube.com/watch?v=HXoFb...eature=related forward to about 1:10...... i never thought a light electric AT6 could stall so violently

scale only 4 me

My Feedback: (158)

Wingloading kills, doesn't matter if it's nitro or E-power,, that's pretty typical behavior for a T-6 weather it be 25 size or 1/4 scale,, gotta keep the speed up all the way to the ground

ccostant

My Feedback: (38)

Oh yea, classic tip stall. I had a Midwest AT6 do the same thing. Was there any washout in the wing?

MetallicaJunkie

http://models-b.ch/magasin/catalog/i...FL4500-450.jpg it has wash-in

exeter_acres

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classic.. "Blame it on the radio... a tip stall will never happen to me" scenario...

cfircav8r

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That or the always deadly "downwind turn."

Hossfly

Sad thing, however there is more to FLYING the machine than meets the eye. TWO things that one can do to assist himself to get used to any airplane with "Barn-Door" ailerons are very simple. Not only are they SIMPLE but they WORK.

While I use it for the first few flights on any barn-door aileron RC model, the relatively low wing area of the so-called WarBird type models really show this technique to be a good one.

#1. REGARDLESS of whatever the plans/directions tell you, NEVER, NEVER have your Center of Gravity (CG) behind 25% of the Mean Aerodynamic Chord (MAC). Later on you may ease it back for showing off, however my bet is you probably will not once you get things going your way. Many kits call for 30-35%. That is only to sell kits. [:@] 25% is the magic number for RC models using sub-sonic convergent airflow. For models with straight or staright taper wings, the average chord of the wing is close anough for MAC purposes.

#2. Especially on those wings with the "barn-door" ailerons, simply crank the ailerons up about 4-6 degrees. This is a very effective "washout" for the wing and makes most everything easier and smoother. Once you get fairly well trained on the machine you just might start taking some out until things get a little squirrely again. I have witnessed many a scale warbird become trash-can material because the pilot's ego just would not allow such a thing. So be it, not my airplane!

Not too long ago I had two experiences. #1 The pilot had a .90 or so Corsair. He was having a can of worms trying to take-off and land. I made my suggestion. He was ready to try anything. We set the ailerons at about a 1/4" high at the inside. WOW, a smooth straight out take-off, performed some rolls and loops after a bit, then a greaser landing, off again and had a nice day. It worked.

Another recent experience I arrived at the field. An "instructor" had a bi-plane of some type, and was having a heck-of-a-time trying to get it flying for a relatively newbie. He had made a couple bad "arrivals" and was replacing some broken spots.
I looked at the model, checked CG, suggested some nose weight, and looked at the ailerons. They were rolled down about 15*. When I asked why, he said that was to give more lift because it was underpowered. I offered my suggestion, he laughed, then I explained the reasons, and he gave it a shot. They flew that airplane for a number of flights and it did very well. That "instructor" doesn't care to converse with me even to this day.

Some years ago, I did Scale Warbird Pylon Racing for a number of years. I had a very neat Scale Spitfire, minimum wing area for the rules, and largest engine for that wing area. It was heavy but fast for that time period. At first I had the same problems. Take-offs were a bear. I finally got the ailerons up to 8* and it became a ***** cat. Then one day as I was passing over a Mustang, he pulled up and whacked my fuselage off right behind the wing. I had no rules for that one but Mother Nature did. Only broke his prop. The field was dry and sandy under the course. The dust really flew up as the Spit went in inverted at about a 30* angle. Very realistic just like a real crash.

Now watching the subject video, I saw a model that had too much aileron throw, was tail heavy, and when it went astray, the pilot was about 10 control movements BEHIND the machine. This can happen to anyone. Prevention is the best cure.

John Casey

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AT6 models are famous for being incorrectly cged.....
the cg is most of the time is way too far aft on the plans , instructions, etc.
You can see the tail try to slide around in the video once when the plane slowed down, the first time
the second time was fatal..but only to the aircraft.

cfircav8r

My Feedback: (1)

Definitely stall spin due to aft CG. I had a Corsair act exactly the same, especially the way it spun while trying to pull out of the dive. It should have had enough airspeed in the dive but during the pull up the C/L kept pulling the nose up past the critical AOA even with very little elevator input.

scale only 4 me

My Feedback: (158)

It does jump some on take off so it may have an aft CG, But it didn't look to pitch sensitive in normal flight to me,, He just let it get too slow,,, then yanked elevator into the second snap.

Pilot Error 100% I say

"Dude I had nothing",,, LOL then why did it pull up & snap the second time??? I wish I had a nickel for every time I've heard that

MikeL

My Feedback: (3)

Yup. Too much elevator throw and not enough experience to know what was happening.

Pretty poor judgment on where to fly, too.

cfircav8r

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Looking at it again I think your right, just a standard stall spin. He slowed way down and tried to pull out of the spin without reducing AOA. The problem is sometimes people don't realize that even though the nose is down the AOA can still be too high.

Rodney

Horace Cain, your assessment of putting in some up trim in both ailerons is a good one, mirrors my experience exactly. I have used that technique on several planes to tone them down and make them more pleasant flyers. I also make all my first flights with a slightly nose heavy or forward CG and then move it back as experience dictates.

scale only 4 me

My Feedback: (158)

If you have to "tone down" an airframe, why not pick an airframe that matches you skills and desire for a gentler flying plane. Why build a Warbird if you want a plane the flies like a polyhedral glider.

RC_Air

Scale only 4 me, you were exactly right about flying too slow and a stall - I flew my Ultimate last weekend for the first time this year and being rusty I forgot how much it needs speed. The Ultimate dropped the opposite wing on a turn to final - a clue that gets your attention lol. Yikes.

The airplane survived, just gave it full throttle and recovered, but the important thing, Hoss had a great point. I've built experimental airplanes with relatively small wing areas and the slight up aileron trick to both airerons definitely works.

I think it's appropriate to accept the technique for scale aircraft because of the fact the physics of 1:1 don't necesarily translate to 1:3 or etc. Anyway, the aileron trick does work

Hossfly

First to Rodney and RC_Air, Thank You Very much for your kind Kudos to the aileron trick.

To "Scale only 4 me" Regardless of the method, trimming an airplane is just that, trimming. Using your trim buttons or making adjustments of the aerodynamic truths all simply results in "trimming".
May I suggest that you try something with one of your skiful picks. Move all the weight such as batteries, fuel tank. etc., aft and get the model to balance at, say, on the 1/2 point of the wing chord at the wing root. Then please advise me if even you would have preferred a more gentler flying airplane.

I have no clue of your real 1:1 SCALE experience. I do have some, not what I really wanted but it included R-2800s, jets, 1, 2, 3, 4, and 6 jet machines, and one with afterburners.
Washing out a wing is standard for airliners. All raising the ailerons on a RC model is just that, adding washout. No, the 3-d or pattern folks don't want or need such, but a heavy wing-loaded aircraft can use it. Some 1:1 scale use a thicker wing section, generally symmetrical at the end of the wing rather than washout with a lifting airfoil at the root. In reality when the pilot puts flaps down for T.O. and landing, that accomplishes adding considerable washout at the wing so extended past the flap area.
Some airplanes such as the DC-10 which really had the washout, could easily be observed when standing some distance behind the airplane The twist was really big time.

Now here are a couple pictures. Both have barndoor ailerons and the mono has considerable up-aileron. It is balanced at 25% MAC and the plans called for 32%. The Bi-plane resulted in my crossing some fabric on the top wing and is teribbly warped. It flies very well, so much trim tabs it doesn't know it is not supposed to fly. It only proves that trim and adjustments can make a poor model fly OK.

All this because I really hate to see new entrants into aeromodling lose airplanes because it seems no one likes to teach basic aerodynamics and transfer that to the newbies in their training stage.

scale only 4 me

My Feedback: (158)

I'm truly unsure of your point,, why would I trim to compensate a ridiculously tail heavy condition, what does this have to do with the price of Tea in China?

In another forum I participate in (Off-road Motorcycles subject matter) there is a guy who always drops the "I'm a Rocket Scientist and you're not so I know what I'm talking about" bomb,, that always cracks me up. My experience is I've been building and Flying "Models" for 38 years. I think over that time frame I've developed a good understanding of aeromodelling

I'd prefer to see Friends, Forum posters and hobby shop sales-persons advise and caution less experienced fliers to pick airframes that match there ability instead of encouraging them to fly something far outside here skill set just because it looks Cool. But the reality is that happens all the time,, Guys jump into demanding Warbird or other scale airframes and tip stall the on landing. The AT-6/SNJ is notorious for this, I've had many over the years and all of them had wash out designed/built into them., If someone had a true love for flying like most of us who stay inthe hobby crash after crash year after year, it's no big deal. But True, some do give up after a few crashes.

I had a good friend that after his 5th crash on his street motocycle I told him,, "Dude, some guys are just meant to drive cars"

Hossfly

Just a method to possibly satisfy your apparent appetite to fly a machine that is extremely difficult to fly. You suggest we lesser persons fly more tame. Personally I can tame the tiger, but to each his own.


So nice of you. I'm sure your friend appreciates your advice. In this aeromodeling business, I rather provide assistance to those that have not yet developed their knowledge of basic aerodynamics. Again, to each his own.