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Old Jun 15, 2012, 09:48 PM
Euphoric flights
GreenAce92_v2's Avatar
United States, NY, Fredonia
Joined Aug 2011
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Non-computer radio mixing

I wanted to know if this mixing (by wire) that I had in mind would work

This is for a four servo flying wing which requires all four servos for turning and only the back two for pitch.

This is for radios that do not have mixing.

I am just wondering if my wiring schematic would work.
The signal depiction is only for clarification not actual like pulse modulation as I don't know how that works.

Can someone check this over, especially when you are climbing and banking (mix of both controls).

I fear that it isn't possible.



p.s. each connected wire is parallel wired as in red red, black black, yellow yellow
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Old Jun 15, 2012, 09:55 PM
AndyKunz's Avatar
Illinois
Joined Sep 2001
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If the question is if you need a computer radio to fly a flying wing, the answer is NO! You can do like some full-size planes and use outer surfaces as ailerons and inner ones as elevators. The Horten wings were done this way, as was the XB-49 I believe.

One thing you DO want to have is differential on the ailerons. You definitely want the inside aileron deflecting higher up than the outboard one goes down. This is easy to accomplish mechanically by not using the control horns and servo arms parallel at neutral.

Andy
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Old Jun 15, 2012, 10:03 PM
Euphoric flights
GreenAce92_v2's Avatar
United States, NY, Fredonia
Joined Aug 2011
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I forgot to mention this; my computer radio was sent in so I only have analog radios

Also specifically my gull wing flying wing has flaps deployed on take off (6 moving surfaces)

So it is rather advanced

In order to avoid a small niche of operations by requiring an advanced radio, I sought after an analogue solution.

If further interested I can show you a video of my control surfaces.


Thank you for that vital piece of information regarding deflection though I don't completely understand that last paragraph?
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Old Jun 15, 2012, 10:12 PM
AndyKunz's Avatar
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In flying wings especially you generally need to have more drag on the inside aileron to provide the yaw for turning, and because of the lower relative airspeed. You get the yaw by differential. Differential is having a different mechanical throw for the same input signal from the stick (ie, you can use a Y harness).

To do this mechanically, you start with the servo arm in a more "down" position (if your horns are on top of the wing, then the servo arm tip is closer to the control surface). As the servo pushes the arm away, it quickly reaches a point of little travel for a large angular rotation (simple geometry). When the servo pulls for up, it has lots of travel before it reaches the same point.

Is your radio gone for a long time? Changing linkages for differential is a lot of work for a short-term outage.

I'd be interested in seeing your model. I really like models of birds!

Andy
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Old Jun 15, 2012, 10:18 PM
Euphoric flights
GreenAce92_v2's Avatar
United States, NY, Fredonia
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Ok I am going to draw models in paint to see if I understand what you are describing.

See my gull wing flying wing is unique. The top view geometry of the wing allows flaps to be installed on the wing so I am not sure if I can implement the yaw aspect.

Are you saying that having this differential is a mix of both yaw and bank?
(Rudder aileron mix) ?

My model is designed for and classed as "Unlimited Sport" rolls on axis, insane exponential climbs (by use of flaps) high speed operation and super slow flight (flap landing).

Yes my radio is gone for like two weeks, however a friend of mine offered me to use his radio. Still I am interested in implementing your suggestions for better overall performance.

Here is what I think / interpret from what you said
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Old Jun 15, 2012, 10:43 PM
AndyKunz's Avatar
Illinois
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I'm downloading the videos you sent. They take forever as I don't have a high-speed connection out here in the boonies. I'll have to get back to you.

Experiment on paper with the geometry. The goal is to see more upward deflection for the same angular rotation.

Andy
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Old Jun 15, 2012, 11:08 PM
Euphoric flights
GreenAce92_v2's Avatar
United States, NY, Fredonia
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"In the boonies" haha
Why don't you steal some internet, decry pt the signal from satellites

Thanks for looking into it.

Still I am curious

Here is an image of more confusion

Additionally: Perhaps this is getting more advanced but even at this scale, should one taper the profile with swept wings?

Also in regards to high speed flying, currently I fly with fully symmetrical airfoil but I can't help but think to add wash, though I fear that the camber may cause problems with opposing angles of attacks (due to the bends "Gull Wing" )

Also for speed runs, I feel like the model would want to balloon if it had any camber.
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Old Jun 15, 2012, 11:20 PM
AndyKunz's Avatar
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You need a reflexed airfoil. There are non-reflexed flying-wing airfoils, but they aren't going to be good for what you're trying to do.

Over on the Builders Forum you might find better advice. There's a guy BMatthews there who is very helpful and very experienced.

Andy
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Old Jun 15, 2012, 11:42 PM
Euphoric flights
GreenAce92_v2's Avatar
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Well thank you very much for your help.
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Old Jun 16, 2012, 08:46 AM
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richard hanson's Avatar
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Your picture is "about right " conceptually.

A flying wing -like a flying anything- has to have something which keeps it pointed in the right direction
A flying wing is nothing more that an exceedingly short moment craft

(Imagine a Piper Ccub then visualize the tail moving forward till it is touching the wing
Same rules apply but now on the flying wing -you need MORE forces because the moment arm (distance) is much shorter .
This is why the reflexed airfoil - either built in or done via moveable surfaces -is a must.
without it -the wing has no force to hold it at the desired angles of attack
- next slide please -
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Old Jun 16, 2012, 09:58 AM
Euphoric flights
GreenAce92_v2's Avatar
United States, NY, Fredonia
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Can't a wing without reflex fly just because it is balanced "neutrally" ?

In the sense that you fly by "angle of attack" as in, the profile is flat, pop elevator a bit to change angle/datum line then aircraft continues to fly at that angle from power of the motor.

By angle I mean new incidence / angle of attack on a fully symmetrical airfoil "plank type wing" so sweep doesn't help with increasing moment arm.
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Old Jun 16, 2012, 10:28 AM
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richard hanson's Avatar
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Quote:
Originally Posted by GreenAce92_v2 View Post
Can't a wing without reflex fly just because it is balanced "neutrally" ?

In the sense that you fly by "angle of attack" as in, the profile is flat, pop elevator a bit to change angle/datum line then aircraft continues to fly at that angle from power of the motor.

By angle I mean new incidence / angle of attack on a fully symmetrical airfoil "plank type wing" so sweep doesn't help with increasing moment arm.
Not very well is the answer as it simply has no stability .
It will glide depending on the cg and power will change climb /dive
you really need an opposing force which can be trimmed to stabilize it
IF one had a super computer which would constantly twiddle control surfaces - it would work
The super fighters have tailplanes which can be seen to constantly move to deliver smooth flight - same thing here .
Some of the little new Bind n fly models from Horizon have accellerometers on board which constantly correct minor inputs and smooth out setups which make these models too sensitive for many flyers -terrific setups!
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Old Jun 16, 2012, 11:01 AM
AndyKunz's Avatar
Illinois
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I recommend you read one of these books:

Model Aircraft Aerodynamics by Martin Simons http://carstensbookstore.com/moaiaebymasi.html
Gliding with Radio Control by Martin Simons http://carstensbookstore.com/glwiracobyma.html
RC Model Airplane Design by Andy Lennon http://www.amazon.com/R-C-Model-Airp.../dp/0879382384

I recommend them in that order.

Andy
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Old Jun 16, 2012, 11:20 PM
Euphoric flights
GreenAce92_v2's Avatar
United States, NY, Fredonia
Joined Aug 2011
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Thank you for the excellent recommendations.

Thanks for all of the responses.

p.s. I thought that the 6th generation fighters are terrible?
I understood what you were referring to but it seems that giving up longitudinal stability (positively stable from geometry and aerodynamics is what I mean) for agility seems like a bad idea. Although I wouldn't think of an F22 as an "efficient" design, it's like a rocket. Not literally but short stubby wings, vertical climb that sort of deal.

A high speed flat airfoil acting like a dive plane on a submarine.
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Old Jun 17, 2012, 08:52 AM
AndyKunz's Avatar
Illinois
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If you have a computer to fly the airplane for you (ie, to stabilize it) then you aren't giving up anything, only gaining agility.

And with the right CG, they are docile: http://www.montanadesign.com/planes/

Andy
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