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Old Nov 04, 2013, 07:59 PM
222 km/hr Parkjet flyer
solentlife's Avatar
Latvia, Ventspils pilsēta, Ventspils
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Originally Posted by Druid_War View Post
What effect does stagger have on the aerodynamics of the wings? and does the stagger count into the chord of the wings?
With such aircraft as the Tiger Moth - the stagger and V of the top wing was for fwd cockpit access ...

BUT as long as distance vertically between wings is enough ... the stagger gives greater limits of CoG movement possible. The stagger comes into more effect as the pitch of the airframe alters ... particularly if angle of incidence is slightly different on each wing.

It is not as some would suggest just cosmetic. It is a development on from early days when Biplanes and Triplanes were needed to get sufficient wing area in as small a span as possible with low power but heavy engines .... but the early bipes had no stagger and when they started to carry loads like bombs etc. - the limitations of no stagger became apparent ... the change of CoG with change of load created a need ...
It must have been awful trying to fly the Gotha's and so on in WW1 without stagger !!

Nigel
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Old Nov 05, 2013, 06:25 AM
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Oklahoma City OK USA Where fakts still exist even if they are ignored
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You can get nearly zero down, max up aileron differential with a single servo and a simple mechanical set up.

Which brand of servo do you have to use?
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Old Nov 05, 2013, 07:23 AM
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Wouldn't this be the perfect application for a program like "FLZ vortex"?

If I were in your shoes I would certainly try to play around with it, trying out different wing arrangements. The visualisation of the air flow might help to achieve some nifty tandem wing design.

Also with a high wing load application: See if winglets make a big difference.
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Old Nov 05, 2013, 09:46 AM
222 km/hr Parkjet flyer
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Latvia, Ventspils pilsēta, Ventspils
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Quote:
Originally Posted by Majortomski View Post
You can get nearly zero down, max up aileron differential with a single servo and a simple mechanical set up.

Which brand of servo do you have to use?
Just move servo arm round a few clicks on the spline ... adjust control rod length. Done.
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Old Nov 05, 2013, 12:03 PM
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You can get differential ailerons off a single aileron servo by using the 4-arm servo output, (good), the 6-arm servo output (better) or if you're using Futaba servos the big blank wheel that comes with.

Principle is to move the UP arm as far away from the aileron as you can. So when the servo moves that connection point will be moving paralel to the aileron hinge line. At the same time the other arm is moving the maximum linear distance towards the aileron horn
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Last edited by Majortomski; Nov 05, 2013 at 06:53 PM.
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Old Nov 05, 2013, 12:46 PM
222 km/hr Parkjet flyer
solentlife's Avatar
Latvia, Ventspils pilsēta, Ventspils
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Quote:
Originally Posted by Majortomski View Post
You can get differential ailerons off a single aileron servo by using the 4-arm servo output, (good), the 6-arm servo output (better) or if you're using Futaba servos the big blank wheel that comes with.

Principle is to move the UP arm as far away from the aileron as you can. So when the servo moves that connection point will be moving paralel to the aileron hinge line. At the same time the other arm is moving the maximum linear distance towards the aileron horn

I have a pic but I can't seem to up load it from here.
Is this for me or OP ?

If for me - save your upload ... been doing it for over 45 yrs !!!

Its simple geometry ...

Nigel
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Old Nov 05, 2013, 06:58 PM
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Quote:
Originally Posted by solentlife View Post
Is this for me or OP ?

If for me - save your upload ... been doing it for over 45 yrs !!!

Its simple geometry ...

Nigel
Nigel, I'm sorry if it appears that I'm confronting everyone of your posts. I'm really not trying to do that.

Our OP has stated a few limitations. He didn't want to use an existing design he wants to design his own biplane.

He can only use 4 servos, my brain forgot he's got 2 for ailerons with the throttle a speed controller not another servo. So yes my single servo upload is no longer needed.

Sparky's pics speak a thousand words

And again I ask you to accept my apology, I'm just managing at being an on line klutz in this thread
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Old Nov 05, 2013, 07:34 PM
222 km/hr Parkjet flyer
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Quote:
Originally Posted by Majortomski View Post
Nigel, I'm sorry if it appears that I'm confronting everyone of your posts. I'm really not trying to do that.

Our OP has stated a few limitations. He didn't want to use an existing design he wants to design his own biplane.

He can only use 4 servos, my brain forgot he's got 2 for ailerons with the throttle a speed controller not another servo. So yes my single servo upload is no longer needed.

Sparky's pics speak a thousand words

And again I ask you to accept my apology, I'm just managing at being an on line klutz in this thread
No problem ...

Nigel
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Old Nov 05, 2013, 09:05 PM
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Joined Oct 2000
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The geometry... yours may vary depending on the total throw of the servo.
Splitting the direction to one side in half with the offset to the servo arm results in the most pushrod travel in one direction and the least in the other, for the full servo throw. when your transmitter doesn't permit programming the travel.
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Old Nov 06, 2013, 03:48 PM
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Anyone have good data on changes in the top wings incidence when compared to the bottom wing? I have read some conflicting data on how it effects the stall characteristics of the plane.
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Old Nov 06, 2013, 04:07 PM
222 km/hr Parkjet flyer
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Quote:
Originally Posted by Druid_War View Post
Anyone have good data on changes in the top wings incidence when compared to the bottom wing? I have read some conflicting data on how it effects the stall characteristics of the plane.
With things like this ... I tend to look through plans ... find one that is similar to what I am considering and compare ... that way I get info from a proven design AND a template to work to.

Nigel
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Old Nov 07, 2013, 07:47 AM
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Sorry double post with the one below
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Old Nov 07, 2013, 07:48 AM
dusty bible = dirty life
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Oklahoma City OK USA Where fakts still exist even if they are ignored
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Quote:
Originally Posted by Druid_War View Post
Anyone have good data on changes in the top wings incidence when compared to the bottom wing? I have read some conflicting data on how it effects the stall characteristics of the plane.
For your one event bird just set them the same.

General concept was at the stalling AOA whichever wings' center of lift was the farthest ahead of the CG stalls first so that the remaining lift contibuted less of a pitching moment until that wing stalled.

The ultimate version of this was the Staggerwing, the front lower wing went first and the rear upper wiing acutally pushed the nose down easing the stall considerably.

And not all model plans get it right. The BUSA Fokker D-VII flys much better if you buld it with angles that are different from what's called out on the plans.
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Old Nov 08, 2013, 01:49 AM
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I have been trying to find information on the distribution of weight between the wings but have been unsuccessful. Do any of you have a good publication or some info I can look over? Also a friend of mine suggested that a servo might burn out doing differential ailerons. Has this happened to anyone on here?
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