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  #1  
Old 02-28-2006, 11:10 AM
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audioflyer audioflyer is offline
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Default Flaps?

I was surprised to see there are no flaps on the Cozy. (And from what I can tell, the other Rutan canards). I think I read that this was in an effort to simplify the design, but I was just wondering:

If flaps were added to the Cozy, where would they go, aerodynamically speaking. I know the air brake is there for the slowing down effect, but it seems like one of the major disadvantages of the Cozy is its long takeoff roll. In the Katanas I fly, for example, we use half flaps on takeoff to generate more lift. Would it be possible to have flaps on the canard for this purpose, change the airfoil and generate lift at a slower speed? I'm sure this has been talked about ad nauseum, sorry!

Have there been any other good ideas about how to shorten the takeoff roll? What about a variable pitch canard?

Thanks.
  #2  
Old 02-28-2006, 11:20 AM
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No need to apologize for askin a question here - ask and answer away

on flaps, canards are a balancing act as both wings create lift. The benefit - stall/spin resistance when flown in CG.

anything you do to the canard, you would probably have to do to the main wing. the canard is designed to stall before the main wing so that the whole plane cannot stall. decrease the stall speed on the canard and ... and ... you could have the canard flyn before the main wings - not a good thing.

we do have a belly board, it is an air landing break, not a speed brake, ima thinkin the correct terms are. is slows you down for landing and i think it also decreases the nose high attitude for landing.

Ask what ever comes to mind - we don't mind and we all come away having learned a little more
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  #3  
Old 02-28-2006, 11:36 AM
JCP JCP is offline
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Default IBIS has flaps

Ther French Canard, IBIS, has flaps..

Question is do they mix the flap with the elevator on the canard ?

JCP
  #4  
Old 02-28-2006, 11:40 AM
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Quote:
The flight control system is the "rigid linkage" type with ball, bell-crank levers and rod connecting joints. The steering and rudder controls are the only system making use of cables. Flight control of the plane is performed through: flaperons (flaps/ailerons) running the whole length of the main wing span, elevator on the canard wing, rudders on stabilizers. The IBIS is flown in a totally classic way.
Wonder if it makes a dif as they are flaperons, think the grizly had some sort of flap arrangement?
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  #5  
Old 02-28-2006, 12:04 PM
Marc Zeitlin Marc Zeitlin is offline
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Default

Quote:
Originally Posted by audioflyer
IIf flaps were added to the Cozy, where would they go, aerodynamically speaking.
On the wing, just like the Starship had/has.

Quote:
Originally Posted by audioflyer
I know the air brake is there for the slowing down effect,
The LANDING BRAKE is there to increase drag and increase the flight path angle on final approach, NOT to slow down. The LB extension speed is approximately 100 kts, so you've already got to be slow to extend it.

Quote:
Originally Posted by audioflyer
Would it be possible to have flaps on the canard for this purpose, change the airfoil and generate lift at a slower speed?
Possible, yes, but you'd put the flaps on the main wing, and then have to have some sort of compensation on the canard to ensure the correct balance of lift at the correct incidence angles. The Starship used a pivoting canard to accomplish this, but it was extremely complex. Other aircraft have used linked flaps, but that is also extremely complex.

In a COZY, the extra complexity would be a killer, both figuratively and literally.

Quote:
Originally Posted by audioflyer
have there been any other good ideas about how to shorten the takeoff roll?
Sure. The simplest thing you can do is use a higher power engine, use a constant speed prop, and raise the ground incidence angle a couple of degrees by lengthening the nose strut an inch or two. Also ensure that the canard is at the top end of the incidence angle tolerance range when mounting it.

It'll never be an RV. But even at 5000 ft. density altitude, at a takeoff weight of about 2200 lb., with a 180 HP engine and a fixed pitch prop, I used about 3700 ft. to lift off the other day. Solo, at 1600 lb., I used about 1500 ft. Reduce those #'s with the changes indicated above.

Quote:
Originally Posted by audioflyer
What about a variable pitch canard?
Very bad idea, from a stability standpoint.
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  #6  
Old 02-28-2006, 12:09 PM
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Quote:
Originally Posted by audioflyer
Have there been any other good ideas about how to shorten the takeoff roll?

Thanks.

yes constant speed prop shortens the take off roll to about 700 to 900 feet (reports vary), also shorten the landing length.

Another way to shorten landing is to increase the rudder size - when both are deployed - they act as a brake
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  #7  
Old 02-28-2006, 12:16 PM
Don P-Factor Don P-Factor is offline
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Default Slats

LE slats on the main wing would be a better idea due to the reversed change in C/L. This would not push the canard load factor higher as the lift increasing devices are deployed.
  #8  
Old 02-28-2006, 12:54 PM
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Interesting, that's about what I figured.
So, technically, what's the difference between an air brake and a landing brake?
  #9  
Old 02-28-2006, 01:01 PM
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I believe it is the speed (IAS) that they can be deployed at
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  #10  
Old 02-28-2006, 01:08 PM
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DrewChaplin DrewChaplin is offline
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Default

Quote:
Originally Posted by Don P-Factor
LE slats on the main wing would be a better idea due to the reversed change in C/L. This would not push the canard load factor higher as the lift increasing devices are deployed.
From my understanding LE Slats allow a wings to continue flying at a Higher Angle of Attack. Pretty much the opposite of how flaps operate. That would mean the nose would be higher, and the propeller closer to the runway on touch down.

I've tried to think threw it once before. It seems too complicated for me, but I'm no engineer.
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  #11  
Old 02-28-2006, 01:58 PM
Don P-Factor Don P-Factor is offline
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LE slats will allow for increased AOA IF that is what is needed for the mission. They also increase lift and will allow a slower flying speed to be achieved at the same AOA. Of course taking into consideration the increased drag due to a seam near the leading edge will offset some value derived by the installation of LE slats. The other alternative is to add retractable lifting area to the Canard for the increased forward pitching moment caused by the deployment of Trailing Edge Flaps if that system is used. The important thing to account for is that when the original designs were created they were to be simple, easy to construct, and light weight.
  #12  
Old 02-28-2006, 02:01 PM
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Quote:
Originally Posted by Don P-Factor
the original designs were created they were to be ...... and light weight.
Near impossible to "improve" the design without increasing this.
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  #13  
Old 02-28-2006, 02:29 PM
ShaleDC ShaleDC is offline
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It's my understanding that flaps on the Beech Starship only lowered landing speeds by 3-5 knots, but added something like 300-500 lbs to the design. If they'd saved some weight, they could have had that 3-5 knots back easy.
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  #14  
Old 02-28-2006, 04:04 PM
Marc Zeitlin Marc Zeitlin is offline
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Quote:
Originally Posted by audioflyer
Interesting, that's about what I figured.
So, technically, what's the difference between an air brake and a landing brake?
Nothing. Two different words for the same thing. On the Rutan derivative canards, they're called landing brakes, and they're used to increase drag to lower the L/D ratio for landing purposes. They CAN be designed for high or low speed deployment - on the canards in question, they're only for use at about 100 Kts or below.

Sometimes the terms "air brakes" and "spoilers" are used interchangeably, although that's somewhat incorrect, because spoilers not only increase drag (like the brake) but also decrease lift (which brakes don't do).
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  #15  
Old 02-28-2006, 09:05 PM
Nathan Gifford Nathan Gifford is offline
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Quote:
Originally Posted by Don P-Factor
...LE slats on the main wing would be a better idea due to the reversed change in C/L...
Yeah, I'm not sure what you would gain from this. The canard, after all, is still going to stall before the wing so I would not think you would shorten your roll. Maybe you might gain some roll authority at low speeds (not a bad thing in my thinking).

Would it affect top end speed? Think of the complexity (construction time, cost, reliability)of self-deploying LEs. By the time you are through, would a CS prop be a better deal?

Thoughts?
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