Where to add Stall strip
06-09-2007 | 09:12 PM
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From: Boynton Beach,
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Where to add Stall strip
Hello all,
I'm getting ready to fly my new CMP chipmunk 40 next week. My understanding is due to its design, it has a tendency to tip stall unless you come in much faster that a regular chipmunk that is offered by other manufactures.
Therefore in order to prevent from tip installing, I'm planning to add "Stall strip" until I get use to it flying characteristic
My question is where I should attach the stall strip, and how thick it should be and what length?
Here is the specification of the wing
Wing span: 57.5" tapered wing
The wing root:10.5" wide
The wing tip: 6" wide
Also the wing seems to be much ticker at the root and getting thinner toward tip.
Thanks
Borna
I'm getting ready to fly my new CMP chipmunk 40 next week. My understanding is due to its design, it has a tendency to tip stall unless you come in much faster that a regular chipmunk that is offered by other manufactures.
Therefore in order to prevent from tip installing, I'm planning to add "Stall strip" until I get use to it flying characteristic
My question is where I should attach the stall strip, and how thick it should be and what length?
Here is the specification of the wing
Wing span: 57.5" tapered wing
The wing root:10.5" wide
The wing tip: 6" wide
Also the wing seems to be much ticker at the root and getting thinner toward tip.
Thanks
Borna
06-09-2007 | 10:14 PM
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From: Riverton,
WY
RE: Where to add Stall strip
A simple stall strip is a piece of triangle balsa attached to the leading edge of the wing. Usually about 1/3 of the wing. It starts inboard at the fuse.
06-09-2007 | 10:49 PM
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From: Keller, TX
RE: Where to add Stall strip
You understand that adding stall strips makes the wing stall sooner, not later, just that the inboard part of the wing stalls before the tip (hopefully) and the stall will be more "manageable". It sounds as though you are trying to fix something that ain't broke. Why not fly the plane first, check out its slow flight manners at altitude get to know how it stalls, then if you think the stall is not manageable, look for remedies, maybe stall strips, maybe just moving the balance point forward. 
06-10-2007 | 06:43 AM
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From: USA
RE: Where to add Stall strip
I got to tell you, I think I've been around this long enough but never heard of a stall strip. Guess I never needed it which is a good sign. When i read this, I'm thinking , here we go again with the gallon jug of "propwash." I still think a chain is being yanked here somewhere.
To follow up here, if it indeed makes the plane stall sooner, why would you want this?
To follow up here, if it indeed makes the plane stall sooner, why would you want this?
06-10-2007 | 07:26 AM
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From: Boynton Beach,
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RE: Where to add Stall strip
Here is the reason I want to add stall strip. First I have this beautiful Chipmunk plane from CMP which is not designed well and it tip stall even under normal landing (I hear that at least from 5 people who owned this plane). So one tip stall means my plane is gone, so why not tame that wing and add some stall strips.
To answer your question as why I want to stall the plane sooner is
I rather stall the plane at the root while the tips are still flying
So as you know, if the stall begins out at the wingtips, we'll see a wing drop (often violently and no way to control that during landing). But if the stall begins at the wing root, all we get is a nose drop, with the plane still under some control.
Adding stall strips will cause the plane to stall at root instead of tips on this particular bad design plane.
So my question to those who are expert is where I should add the stall strip, and how long should be the stall strip.
Thanks
Borna
To answer your question as why I want to stall the plane sooner is
I rather stall the plane at the root while the tips are still flying
So as you know, if the stall begins out at the wingtips, we'll see a wing drop (often violently and no way to control that during landing). But if the stall begins at the wing root, all we get is a nose drop, with the plane still under some control.
Adding stall strips will cause the plane to stall at root instead of tips on this particular bad design plane.
So my question to those who are expert is where I should add the stall strip, and how long should be the stall strip.
Thanks
Borna
06-10-2007 | 07:58 AM
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From: USA
RE: Where to add Stall strip
I'm just curious here, can this be built in as part of the leading edge and covered so that it does not look like something stuck on by some "Elmers."
06-10-2007 | 08:10 AM
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RE: Where to add Stall strip
ORIGINAL: borna
So as you know, if the stall begins out at the wingtips, we'll see a wing drop (often violently and no way to control that during landing). But if the stall begins at the wing root, all we get is a nose drop, with the plane still under some control.
Adding stall strips will cause the plane to stall at root instead of tips on this particular bad design plane.
So as you know, if the stall begins out at the wingtips, we'll see a wing drop (often violently and no way to control that during landing). But if the stall begins at the wing root, all we get is a nose drop, with the plane still under some control.
Adding stall strips will cause the plane to stall at root instead of tips on this particular bad design plane.
A stall that begins at the root or at the tip will cause one wing to drop if only one wing stalls. It doesn't matter where the stall starts, the nose isn't going to droop unless both wings stall at the same time. And when the stall is instigated by the usual newbie practice of steering the takeoff or landing with the ailerons, most probably only one wing is going to stall.
So my question to those who are expert is where I should add the stall strip, and how long should be the stall strip.
Thanks
Borna
Thanks
Borna
But since you're insistent and think stall strips are going to make the airplane stay under control in a stall, the Corsair used a stall strip on some aircraft. It was probably about 5" or 6" long on the full scale Corsairs. They had a wing span of roughly 41feet. It was placed just outboard the guns on the starboard wing only so it was roughly 1/3 the halfspan outboard. It was also not installed on some of the later aircraft as it's effectiveness was questioned.
Steer your landings and takeoffs with the rudder and land with just a touch more throttle.
06-10-2007 | 08:15 AM
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RE: Where to add Stall strip
ORIGINAL: Trollmaster
I'm just curious here, can this be built in as part of the leading edge and covered so that it does not look like something stuck on by some "Elmers."
I'm just curious here, can this be built in as part of the leading edge and covered so that it does not look like something stuck on by some "Elmers."
It will be most effective if it has a sharp leading edge. And most of them do not blend into the Wing LE at the ends of the device.
06-10-2007 | 09:12 AM
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From: USA
RE: Where to add Stall strip
ORIGINAL: da Rock
What you want to happen and the way you describe it working isn't what's going to happen or the way it's going to work. A number of people tried to expain that in the other thread you started.
A stall that begins at the root or at the tip will cause one wing to drop if only one wing stalls. It doesn't matter where the stall starts, the nose isn't going to droop unless both wings stall at the same time. And when the stall is instigated by the usual newbie practice of steering the takeoff or landing with the ailerons, most probably only one wing is going to stall.
And the answer from some of the experts is not to bother with the stall strip. Fly the airplane with a couple of clicks more throttle on landing. Take it off without SLAMMING the throttle to full. Ease the throttle and by steer with the rudder.
But since you're insistent and think stall strips are going to make the airplane stay under control in a stall, the Corsair used a stall strip on some aircraft. It was probably about 5" or 6" long on the full scale Corsairs. They had a wing span of roughly 41feet. It was placed just outboard the guns on the starboard wing only so it was roughly 1/3 the halfspan outboard. It was also not installed on some of the later aircraft as it's effectiveness was questioned.
Steer your landings and takeoffs with the rudder and land with just a touch more throttle.
ORIGINAL: borna
So as you know, if the stall begins out at the wingtips, we'll see a wing drop (often violently and no way to control that during landing). But if the stall begins at the wing root, all we get is a nose drop, with the plane still under some control.
Adding stall strips will cause the plane to stall at root instead of tips on this particular bad design plane.
So as you know, if the stall begins out at the wingtips, we'll see a wing drop (often violently and no way to control that during landing). But if the stall begins at the wing root, all we get is a nose drop, with the plane still under some control.
Adding stall strips will cause the plane to stall at root instead of tips on this particular bad design plane.
A stall that begins at the root or at the tip will cause one wing to drop if only one wing stalls. It doesn't matter where the stall starts, the nose isn't going to droop unless both wings stall at the same time. And when the stall is instigated by the usual newbie practice of steering the takeoff or landing with the ailerons, most probably only one wing is going to stall.
So my question to those who are expert is where I should add the stall strip, and how long should be the stall strip. Of course I wuld think to eliminate stall is a skill level here.
Thanks
Borna
Thanks
Borna
But since you're insistent and think stall strips are going to make the airplane stay under control in a stall, the Corsair used a stall strip on some aircraft. It was probably about 5" or 6" long on the full scale Corsairs. They had a wing span of roughly 41feet. It was placed just outboard the guns on the starboard wing only so it was roughly 1/3 the halfspan outboard. It was also not installed on some of the later aircraft as it's effectiveness was questioned.
Steer your landings and takeoffs with the rudder and land with just a touch more throttle.
So all this boils down to why the Chipmunk is not the most popular in the nest eh? I see the planes from time to time but nothing serious.
06-10-2007 | 11:29 AM
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From: portland, OR
RE: Where to add Stall strip
Just because you've been around a long time and have never heard of a stall strip, doesn't mean it doesn't exist Check out photos of the Military Chipmunks and you will see a small triangle strip on the leading edge of the wing near the fuselage... "Stall Strip" Not just a lot of propwash.... which too really exsists.......
Check out photos of the Military Chipmunks and you will see a small triangle strip on the leading edge of the wing near the fuselage... "Stall Strip" Not just a lot of propwash.... which too really exsists.......
06-10-2007 | 11:43 AM
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RE: Where to add Stall strip
Borna:
Nothing you can do to ease the tip-stall will be pretty. A stall strip can be as simple as a popsicle stick, cut in half lengthwise and glued to the front of the leading edge sticking straight forward. It should have the inboard end at the side of the fuselage.
The problem with stall strips is that you need to experiment to find the right size to do what you want to do. And while you are experimenting, you are probably crashing.
Call Horizon Hobbies and order a set of leading edge droops from their P-51 or F-22 trainers, and make them fit your airplane. They will be ugly, but that's the only way you have any real chance of eliminating the tip-stall on the first try. The other benefits of the droops are that they add to the wing area (reduced wing loading) and they make it stall later, not sooner like the stall strips.
Have you considered donating the Chipmunk to a school or charity as a static model and writing it off on your taxes?
Jim
Nothing you can do to ease the tip-stall will be pretty. A stall strip can be as simple as a popsicle stick, cut in half lengthwise and glued to the front of the leading edge sticking straight forward. It should have the inboard end at the side of the fuselage.
The problem with stall strips is that you need to experiment to find the right size to do what you want to do. And while you are experimenting, you are probably crashing.
Call Horizon Hobbies and order a set of leading edge droops from their P-51 or F-22 trainers, and make them fit your airplane. They will be ugly, but that's the only way you have any real chance of eliminating the tip-stall on the first try. The other benefits of the droops are that they add to the wing area (reduced wing loading) and they make it stall later, not sooner like the stall strips.
Have you considered donating the Chipmunk to a school or charity as a static model and writing it off on your taxes?
Jim
06-10-2007 | 02:53 PM
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From: surrey,
BC, CANADA
RE: Where to add Stall strip
By letting the root stall first you will probably have a tip stall immediately after that event.Fly in with a shallow approach,avoiding sudden throttle blips,maybe keep some power until you are in ground effect,a glide at idle will be a problem.Check for lateral balance too.
Good luck with the maiden
Good luck with the maiden
06-10-2007 | 03:25 PM
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From: Boynton Beach,
FL
RE: Where to add Stall strip
Ok guys thanks for all the advice. I can tell you that I learned a lot in the last 2 days about tip stall, characteristic of tapered wing, stall strip, and land with rudder.
From what I been hearing stall strip is not a good idea, so you guys convinced me not to use it since is not going to make the plane land any better. .
However what I don’t understand is then what is the benefit of stall strip if is not going to improve the stall characteristic of the plane??
I have read it that it is used in a real plane and here is a picture of the military chipmunk with stall strip.
Thanks
Borna
From what I been hearing stall strip is not a good idea, so you guys convinced me not to use it since is not going to make the plane land any better. .
However what I don’t understand is then what is the benefit of stall strip if is not going to improve the stall characteristic of the plane??
I have read it that it is used in a real plane and here is a picture of the military chipmunk with stall strip.
Thanks
Borna
06-10-2007 | 03:46 PM
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From: surrey,
BC, CANADA
RE: Where to add Stall strip
In a model this small,full size functions may not necessarily scale down to your benefit.
Fly it and maybe add the strip later,then you will know for sure if its to your advantage.
Fly it and maybe add the strip later,then you will know for sure if its to your advantage.
06-10-2007 | 04:31 PM
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RE: Where to add Stall strip
Full scale aerodynamics do not translate to models. That little stall strip in the photo might help make the stall start at the root of the full scale, but it wouldn't do a thing for a model.
Think about it. A tip stall is caused when the tip stalls before the root. The purpose of a stall strip is to make the root stall sooner, so that it stalls before the tip does. That means the stall starts sooner (at a faster airspeed) with the strips than with out them.
Jim
Think about it. A tip stall is caused when the tip stalls before the root. The purpose of a stall strip is to make the root stall sooner, so that it stalls before the tip does. That means the stall starts sooner (at a faster airspeed) with the strips than with out them.
Jim
06-10-2007 | 04:31 PM
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From: Riverton,
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RE: Where to add Stall strip
A wing with a sharp leading edge will stall sooner than a wong with a rounded leading edge. The stall strip is not bullet proff but it works by stalling the inboard part of the wing first. Tis caused the nose to drop and airspeed come up and you keep flying. Even if one wing still stalls a little sooner than the other, the ailerons are still working so you can keep the plane level.
Washout in the wing tip will do the same thing.
On full size planes they often stalled one wing first, so they all a stall strip to the other wing to make both wings stall at the same time. In the old days this was done by cut and try.
Washout in the wing tip will do the same thing.
On full size planes they often stalled one wing first, so they all a stall strip to the other wing to make both wings stall at the same time. In the old days this was done by cut and try.
06-10-2007 | 06:23 PM
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From: USA
RE: Where to add Stall strip
ORIGINAL: anonymouse
Just because you've been around a long time and have never heard of a stall strip, doesn't mean it doesn't exist Check out photos of the Military Chipmunks and you will see a small triangle strip on the leading edge of the wing near the fuselage... "Stall Strip" Not just a lot of propwash.... which too really exsists.......
Just because you've been around a long time and have never heard of a stall strip, doesn't mean it doesn't exist
Check out photos of the Military Chipmunks and you will see a small triangle strip on the leading edge of the wing near the fuselage... "Stall Strip" Not just a lot of propwash.... which too really exsists.......
Follow along genius, were already past that. This is good information here, no need for the smart cracks
06-10-2007 | 06:49 PM
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RE: Where to add Stall strip
Hey Borna;
I just had an idea. Your objective is to stop the CMP Chipmunks tip-stall tendency. You can do that with washout, raised barn door ailerons, stall strips or leading edge droops. Leading edge droops are ugly, stall strips increase the stall speed and may not eliminate the tip stall until you try a lot of different configurations, washout would require a complete rebuild of the wings, and you don't have barn door ailerons.
OK try this; Cut the ailerons about 60% of the way out from the fuselage, raise the outer portion 1/8 inch (at the trailing edge) and glue it back onto the inner portion. (Reinforce the joint with a piece of music wire bent to shape and inset into the trailing edges if you think you need to.) This will create washout and be the same as raising barn door ailerons.
Easy, not bad looking and it will probably work.
Jim
I just had an idea. Your objective is to stop the CMP Chipmunks tip-stall tendency. You can do that with washout, raised barn door ailerons, stall strips or leading edge droops. Leading edge droops are ugly, stall strips increase the stall speed and may not eliminate the tip stall until you try a lot of different configurations, washout would require a complete rebuild of the wings, and you don't have barn door ailerons.
OK try this; Cut the ailerons about 60% of the way out from the fuselage, raise the outer portion 1/8 inch (at the trailing edge) and glue it back onto the inner portion. (Reinforce the joint with a piece of music wire bent to shape and inset into the trailing edges if you think you need to.) This will create washout and be the same as raising barn door ailerons.
Easy, not bad looking and it will probably work.
Jim
06-10-2007 | 07:13 PM
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RE: Where to add Stall strip
One more point you might want to consider if you plan on doing any aerobatics:
Stall strips are the only solution that will work the same upside down. Washout, raised barn door ailerons and leading edge droops will all make the airplane more likely to tip stall when it is inverted.
About now you are probably wondering why most of the Caps, Extras, Edges, Yaks, pattern planes, and sport planes with tapered wings don't have this problem. The answer is careful selection of root and tip airfoils (They are not the same.) to calibrate the stall characteristics at the root and the tip. A good sport aerobat will have the tip stall first, but gently, and the root later but more abruptly. The result is a wing that will stall flat if the stall is approached slowly and will snap roll either way if the pull up is more radical. The pilot can then control the stall characteristics by the speed and magnitude of his elevator inputs, and control the direction of the snap with the rudder.
The CMP Chipmunk, unfortunately, seems to have been designed by someone who doesn't understand that.
Jim
Stall strips are the only solution that will work the same upside down. Washout, raised barn door ailerons and leading edge droops will all make the airplane more likely to tip stall when it is inverted.
About now you are probably wondering why most of the Caps, Extras, Edges, Yaks, pattern planes, and sport planes with tapered wings don't have this problem. The answer is careful selection of root and tip airfoils (They are not the same.) to calibrate the stall characteristics at the root and the tip. A good sport aerobat will have the tip stall first, but gently, and the root later but more abruptly. The result is a wing that will stall flat if the stall is approached slowly and will snap roll either way if the pull up is more radical. The pilot can then control the stall characteristics by the speed and magnitude of his elevator inputs, and control the direction of the snap with the rudder.
The CMP Chipmunk, unfortunately, seems to have been designed by someone who doesn't understand that.
Jim
06-10-2007 | 08:50 PM
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From: portland, OR
RE: Where to add Stall strip
Well!!!! Excuse me!!!!!... I didn't think you would be so touchy, but you seemd to doubt a fact that any good scale modeler would know......I was just trying to give you confirmation that such an item existed........Won't step on YOUR toes again, PAX.....[:-]
06-10-2007 | 10:05 PM
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From: surrey,
BC, CANADA
RE: Where to add Stall strip
I really think its in the hands of the pilot that can get a stall or avoid one,no need for gimmicks sometimes. This is a CMP product,a low end manufacturer,some aircraft maybe misaligned,and some may fly quite well,check your incidences and wing panels for warping,maybe a cleaned up one will need no mods and fly nicely.I would never modify an airframe without going for a test run first and making sure things are as good as you can get them before flight.
06-10-2007 | 10:08 PM
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From: Poolesville, MD
RE: Where to add Stall strip
ORIGINAL: borna
Here is the reason I want to add stall strip. First I have this beautiful Chipmunk plane from CMP which is not designed well and it tip stall even under normal landing (I hear that at least from 5 people who owned this plane). So one tip stall means my plane is gone, so why not tame that wing and add some stall strips.
Here is the reason I want to add stall strip. First I have this beautiful Chipmunk plane from CMP which is not designed well and it tip stall even under normal landing (I hear that at least from 5 people who owned this plane). So one tip stall means my plane is gone, so why not tame that wing and add some stall strips.
As Da Rock and Trollmaster have pointed out, just keep on the throttle a bit or set the idle to a higher rate using the trims, and only bring it down once the wheels are on the ground.
I have a couple of planes that are supposed to weigh 8lbs and have come in at over 12+ lbs. These WILL tip stall with ease. I've never had a problem coming in just a little "hot" like with most tail draggers with the idle trim set all the way up.
Remember tips stalls mean that you are flying your plane too slowly for the situation.
When you maiden the plane spend most of the time after you have it initially trimmed, to practice approaches, then stalls at higher altitudes to get yourself set up for your new "normal" landings.
06-10-2007 | 10:13 PM
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From: Boynton Beach,
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RE: Where to add Stall strip
Thanks all, these are all great information.
Jim, I like the idea of cutting the ailerons about 60% of the way out from the fuselage. I will do some research on that to see how it works.
Thanks
Borna
Jim, I like the idea of cutting the ailerons about 60% of the way out from the fuselage. I will do some research on that to see how it works.
Thanks
Borna
06-11-2007 | 12:01 PM
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From: Sinking Spring,
PA
RE: Where to add Stall strip
why not have a more experienced pilot maiden it and see what he/she thinks about it's stall characteristics? I had a plane that tip stalled constantly when new and I hated it, but kept flying it. Not long after I can to like the plane and just avoided tipstall situations i.e. flew the plane how it was supposed to be flown! For me I came from flying a fun fly airfoil with no bad habits. IT just took some adustment time.
Mike
Mike
06-11-2007 | 04:15 PM
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From: Lake Ronkonkoma,
NY
RE: Where to add Stall strip
Just to add to the fun, one design benefit of stall strips on a full size aircraft is to cause only a small inboard section of the wing to stall at a lower angle-of-attack so that the turbulent airflow created by the stall will be felt on the elevator warning the pilot of an impending stall condition. A stall starting at the tip will not be felt by the pilot until it has progressed sufficiently inboard to lose the aerodynamic effectiveness of the ailerons for lateral control. Then a-rolling you will go. I suspect, based on the small size of the pictured Chipmunk strip, stall warning, not stalling, is the objective.
