P-51 and Tip Stalls

Let me start by asking exactly what is a tip stall and how do you handle them?
OK, I am going to build a P-51 ARF and am looking for a way to eliminate so
called tip stalls if thats possible. I have "heard" that if you glue a triangle shaped lenth of balsa on the upper trailing edge of each aileron, this will solve the problem. The balsa piece is triangle stock from a quarter inch square stock. Does this make sense?
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Hi,
Stalling is loss of lift. It can happens when airspeed is too low and/or attak angle is too high. When it happens at wing tips before roots you loose also aileron control. At safe altitude you can usualy recover. Not so at 2' over track. If you add (ugly) triangle balsa pieces as you describe or slightly raise both ailerons than tip stalls is retarded but not eliminated. If you scratch build you can add some tip washout (less angle at tip than root). For an ARF check if that washout is not readily present.
Happy landings, Daniel
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Watchur6 wrote:

handle
eliminate so

a
aileron,
Doesn't really make sense, and it's ugly, too. Washout helps prevent tip stalls. This is angling the tip of the wing down at the leading edge. This keeps the tip flying when the root stalls. Keeping the plane above stall speed also helps. :) If you fly too slowly, and/or at too high of a AOA, ANY plane will stall. Keep the weight low, too. A lighter plane has less wing loading, and will fly more slowly before stalling that a heavier plane will.
I've never heard that the P-51 is prone to tip stalling. What makes you think you'll have a problem?
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Tip stalling is when the wing tips stall before the root. Usually one side stalls first and the plane flips over...crash. This usually happens on landing approach where the AOA is too great or airspeed too small. I happens more frequently with higher wing loading.
That said, a P-51 is nore prone to tip stalling than any other model. A heavily loaded Extra or Sukhoi will do exactly the same thing.
Which ARF are you assembling? I have flown several of the EZ 40 size and they are a dream to fly with no bad habits. Some of the others which are near clones are the same.
--
Paul McIntosh
http://www.rc-bearings.com
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"I'm going to build a ARF plane" ????!!! Have we come that far????
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Build = construct, put up, erect, make, put together, manufacture, fabricate, (and the one I think you prefer) assemble. So yes, he is going to build an ARF. CH

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Just about any 'plane will tip stall if conditions are right. I don't know about this particular one but most generally a heavily loaded warbird is seen to tip stall on takeoff. This is a result of using aileron to steer instead of rudder when speed is low and the nose is high. The trick of adding triangular strips to a wing is to allow the inboard section to stall before the outboard. However, the strips are applied to the inboard L/E not the ailerons. Even with them on, it will do little or nothing for bad flying. It strikes me that putting something on the ailerons would cause some serious stall problems on the outbd end of the wing. In actual practise, next time you are near a Cessna 150, take a look at the L/E near the cockpit and you will likely see some stall strips. Do an "image search" on google using "stall strips" as the search argument. The first couple of hits show you and tell you a great deal about this method. Gord Schindler MAAC6694

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Gord Schindler wrote:

don't know

is
steer
The other way around. Aileron without rudder will cause a slip, which is relatively safe. Rudder only causes a skid, which is asking for a wing drop at low speed. Flight should be coordinated to avoid slip or skid. Of course, using aileron to pick up a wing when it's dropping in a stall can often deepen the stall and make it drop faster. Depends on the airplane.
Dan
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Ummmm... I respectfully disagree...
    Gord's post was correct IMHO...
    At too low airspeed, the AOA is necessarily high to compensate.
    Applying aileron (only) in this situation, (usually recovering from the turn to final) causes an adverse yaw. This down going aileron on the wing that is already travelling slower on the inside of the turn is slowed even more by the adverse yaw, - the down aileron increases the (effective) AOA of this wing tip even more, and the inside wing tip stalls, rolling the aircraft OPPOSITE to the applied aileron command.
    Soooo... the "I got hit" call is heard, - after all, it DID roll OPPOSITE to the stick movement ... right?
    I believe what Gord is saying is correct. Applying aileron ONLY in this situation is a recipe for disaster, and is too often the result. Add this mishandling to a clean P-51 with tapered wings,or the eliptical wing of a Spit, and a (usually) higher wing loading of a warbird, and many end up in a pile because the pilots were never trained to fly properly.
    LOTS of rudder is required in this situation, and if it skids the aircraft out of the turn, speeding up the inside wing tip (good) the aileron can be used (a bit to help) with greater safety.
    One should LEAD (apply first)recovery rudder, BEFORE the aileron is moved.
    Watch others fly, and observe how many fly around with their left thumb on the box, reaching the left stick only to adjust the throttle....
    If this is you, please learn to use the rudder properly before you fly a critical aircraft.
    Try a Cub/Citabria with barn door ailerons, you WILL learn about the rudder! :)
    We played with an Aeronca Champ one day, (full size) whatta HOOT!
    Shoving the stick hard to one side merely allowed you to view the direction ahead out the side window!
    You have to LEAD rudder then aileron into the turn, and LEAD rudder to recover..... (with the Champ)
    I was demonstrating slow flight to a friend in our 172 last week, 20 deg flap, airspeed (what we could read) was less than 40 knots, stall warning horn blaring, and doing gentle figure eights WITH THE RUDDER ONLY. Touching the ailerons would have dropped a wing instantly!
    I observe 3 of 4 modellers not using the aileron and elevator correctly while taxing the aircraft in a wind.
    If you are unfamiliar with the terms "dive away" or "climb into" , (the wind, while taxing) then find a pilot who does and have them show you , it can save an aircraft.
    OK... rant off! :)
    Gord, did I follow your thoughts correctly?
    Cheers!
    Dave
On 22 Feb 2005 17:01:30 -0800, Dan_Thomas snipped-for-privacy@yahoo.com wrote:

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Dave wrote:

I agree 100%, Dave. When I flew my first Dr. 1, I had trouble keeping it straight on landings. It weathervanes terribly. I bought and installed a gyro on the rudder. It never would respond fast enough or with enough movement. After about 2 weeks, I took it off and learned to fly the rudder. To those of you who don't know how to do this, try it sometime. There's nothing prettier than a multi-wing plane sideslipping against a crosswind on final.
Dr1
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Absolutely keerect DR. Nothing gets their attention more than a beautifully executed slip to a perfect three pointer. Perfect way to put the bird on the numbers when you are too high on a dead stick.
--
Tally Ho!
Ed
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Coordination is the key. Whatever rudder is required to keep the airplane from skidding or slipping. Incidentally, using lots of rudder to speed up the inside wing is a SLIP, not a SKID.
> I was demonstrating slow flight to a friend in >our 172 last

That's strange. I'm an full-scale instructor, been flying 172s and 182s and 185 and Champs and Citabrias and homebuilts for years, and we teach coordinated turns in slow flight to avoid initiating a skid with rudder only and asking for that spin. Right out of the official Flight Training Manuals. We show students what happens in slow flight in a Citabria when you skid it with rudder: it spins. And a 172 is so forgiving you can pick up a dropping wing while in the stall.
>Try a Cub/Citabria with barn door ailerons, you >WILL learn

I just landed a few minutes ago from a brief check flight in one of our Citabrias. Taildragger training is my specialty.
Dan
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I must be missing quite a few replies/etc. Two newsgroups and neither is doing a proper job. Oh well.
I never had a problem flying Citabria/Decathlons because I always treated them as though they were very short coupled beasties that could be nasty if you let your guard down. Once that was taken into consideration, they were no more difficult to fly than anything else.
The trick to flying short coupled, conventional geared planes successfully is to anticipate the needed input before it is needed and apply a little by leading it just a little. Everything looks beautiful, proper and straight to the casual observer, which leads them to believe that it did not require a correction at all. Then when they try it - snap!
Ed Cregger
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By George Dan, I think you nailed it ;) Too much rudder = skid, too little = slip. A *little* over simplified cuz sometime you don't "step on the ball" you just release some/all rudder pressure. More of us RC types should learn that solo doesn't mean you are a pilot - it just means that the instructor thinks you know enough to get out of trouble. At least that's how it should be <s>. Solo is the beginning of a new learning process that should last until they pry your hands off the stick <VBG>.
--
Tally Ho!
Ed
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Hehe...
Conversation just after my 1st solo flight..... (full size)....
Instructor.. "How do you feel?
Me... "Great"
Instructor..... 'You should, 'cause you just earned the right to learn how to fly"
I never forgot that!
Dave
On Wed, 23 Feb 2005 17:48:43 -0500, "Ed Forsythe"

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Agreed!

Ummm.... it becomes a slip if you HOLD the rudder and not allow (or help) the low wing rise to level....initially it is a yawing rotation around the vertical axis that "speeds up" the low wing in this example.If one holds the rudder and completes a "flat" turn, (wings held leve)l, are you "skidding " around the turn? - or "slipping" around the turn? ....I gotta think about it... :)

we

Correct...Co-ordinated flight is the most important skill here... In my example, the use of the ailerons is avoided because it will drop a wing, and the rudder is gently used to turn. I was almost into the "reversed control" region of the flight envelope, WAY below what would be normal "slow flight". My instructor taught to use the rudder to keep wings level when approaching a stall, the ailerons don't work very well anyway at that speed... except to drop a wing tip.... Our 172 is the "M" model, with the larger leading edge radius..VERY difficult to spin, but will!
My friends Citabria will do as you describe, but seems to take a lot of rudder to spin from level.. takes a HARD shove of the rudder to drop a wing, but it has to be well below normal "slow flight" before the spin can be started this way.
Been a while, will try it next time up with him...

I have limited time in full size draggers, but most of my models are taildraggers....
What fun!
    Dave
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rotation
Watch the ball next time you recover from a turn using just rudder. It will swing toward the low wing, and therefore you have a slip. Sloppy flying. At really low airspeeds you could cause the outside wing to drop and roll over into a spin. Been there, demonstrated that. If you can't use the ailerons to recover from a turn, you are WAY too slow. Approach speed should be around 1.3 times stall speed, and on the base leg it should be about 10 knots higher. Nowhere near aileron-reversal speeds.

Nope. Get it into a 60 MPH glide, and start skidding it around a turn using rudder and opposite aileron to keep the wing up. Keep the nose up to keep the speed down. Tighten the turn some more and the wing will flick down and there you have it. Better have lots of altitude. This is the killer turn: base-to-final, a bit low, pilot has overshot runway centerline and wants to tighten the turn but he know steep turns near the ground are bad, so he holds the wing up with aileron and tries to get it around with just rudder, holding the nose up to stretch the glide, and one more Citabria and pilot are written off.
Dan
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All of this points out why I try to land a bit hot.
Why? Because try as we might to assess the airspeed of the model, there are vortices constantly parading around on the airfield. This is not the exception, it is the rule.
Get the models nose into the wrong side of a vortice (wind rotating toward the nose of the aircraft) and you have just decreased your airspeed by the airspeed of the wind in the vortice. Generally, you cannot see its effect until it is too late, if you are a bit too slow. Keep the airspeed a bit above what is necessary and you will fly right through it before you can become aware of its existence.
Ever see those little burbles that your model displays on approach? Whoot - there it is...
I try to teach my student pilots to learn how to fly their models at speed near the ground. I then teach them to do low, flat approaches, field permitting, while carrying a bit of throttle. Yes, it makes them nervous at first, that is normal. But after a while they become used to flying with full control authority and they do not fear landing as much as they did when they were attempting to land with the throttle all the way back and the nose pointed downward, praying and hoping that the wind would not upset their approach. You make your own luck in this hobby.
Ed Cregger
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OK...
On 24 Feb 2005 07:25:18 -0800, Dan_Thomas snipped-for-privacy@yahoo.com wrote:

Correct..but my suggestion is only to use rudder momentarily to avoid a yaw into the turn due to adverse yaw produced by heavy application of aileron to roll out of the turn...
If

Exactly..
Yikes!
You did not mention anything about OPPOSITE AILERON! OR keeping the wing up! (until now)..
Agreed.. this would be a killer!
I understood your example to be rudder application only....
This is

Agreed...
I never feared steep turns at any altitude. Co-ordinated, and at adequate speed, they work just fine..
Dave

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The most effective way to eliminate tip stalls (I hate that term) with any aircraft is to land at the proper airspeed.
TAS

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