Flying wing with split drag surface on tower for pitch control? - Page 4 - RC Groups
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Dec 31, 2012, 05:39 AM
Registered User
You can deduce sideslip with gyroscopes and accelerometers only if you presume the air to be in a steady state (and it takes a fair deal of computing power). A sideways gust will cause a large change in yaw without affecting much accelerometers or gyroscopes. That's why full sized planes still have several air sensors to integrate the data obtained by the inertial navigation system.
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Jan 02, 2013, 09:55 AM
You know nothing....
Stuart A's Avatar
Originally Posted by Sparky Paul
It taxis... will it take off?
Interesting idea.My money's on it working.
Kent and myself are working on split fins as a way to knock speed off a plank for landing.(Nurfluegal forum)
Also in the show your Nurfluegal thread there's a vid/ pic of a Horten wing with a canard.
Jan 02, 2013, 10:37 AM
Registered User
I think it will work with a couple of "but"s thrown in. It might make the wing prone to tumble. and I am not sure how well that fin will interact with the swept wing.
Jan 02, 2013, 12:27 PM
Ascended Master
Sparky Paul's Avatar
It started out as a simple way to make drag rudders for a wing, and it just grew.
I noticed in the NASA stuff on the Shuttle they mention the speed brake and pitch control of the split rudder but they concentrate on the speed brake function, with nothing more on using it for pitch.
It is a god-awful thing to paste on a smooth wing.
I'm going for a wheeled takeoff, because the instant response needed for a hand launch could be in the wrong direction, or the thing could just be unflyable. The takeoff run would permit observing what is going on and maybe correct for that.
It's too cold outside to do anything more than bring in the paper during the day... Grumpp....
Jan 02, 2013, 12:46 PM
internet gadfly
nmasters's Avatar
Originally Posted by Sparky Paul
I noticed in the NASA stuff on the Shuttle they mention the speed brake and pitch control of the split rudder but they concentrate on the speed brake function, with nothing more on using it for pitch.
Real airplanes pitch up to slow down
Jan 02, 2013, 12:51 PM
Registered User
Big composited delta wing with leading edge root extensions. The brake probably becomes less effective as the AOA increases (its angle to the airflow decreases, and get blanketed by the wing and fuselage wake), ending up in a stable configuration where the wing is actually braking the plane. It also helps using the trailing edge surfaces as flaps. After all, it's not meant to go around, so I don't think there's a situation where you'd suddenly close the airbrake.
Jan 02, 2013, 01:14 PM
Ascended Master
Sparky Paul's Avatar
I was there when Columbia became the first spaceship to land on Earth. It resembled what would happen were the world's largest tool box to be dropped from 50,000 feet, but it came down faster! :0
The effect of the brake would be pull the nose up and slightly decrease the rate of plummet. And stretch the plummet a bit if it was going to be short.
Actually climbing that thing would require adding power, which it had none of.
I'm hoping this apparatus will have some of the characteristics of an elevator, but less powerful, with any number of unexpected (pernicious) side effects.
Jan 02, 2013, 01:44 PM
Registered User
I expect severe pitchup even with the brake closed
Jan 02, 2013, 02:12 PM
Ascended Master
Sparky Paul's Avatar
I've adjusted the ailerons down from the elevon trimmed position, so that any pitchup will be caused by the vertical, and expect to have the elevator trim set all the way down.. almost closed, for the takeoff run, leaving some down "elevator" just in case it might need it.
Jan 02, 2013, 03:31 PM
Ascended Master
Sparky Paul's Avatar
Braving the arctic wind, on the street outside with the ailerons down as mentioned, it showed no inclination to take off.
Pulled the ailerons up 4 turns on the pushrods.. downhill into the wind, it shows promise.. steers nicely, but not much of any indication that it will take off with full "elevator".
I need a longer less restricted area, and to pull up the ailerons more.....
Jan 02, 2013, 03:55 PM
Registered User
richard hanson's Avatar
You need a pretty good AOA to get free of the ground
The tiny indoor stuf I posted last year showed same thing .
set the gear such that you have a good AOA - it's a cut n try (what! no calculations!)
Jan 02, 2013, 07:51 PM
Ascended Master
Sparky Paul's Avatar
Going into the ridiculous part of the state of the art, it's kinda difficult to determine how to work up to a workable solution, or the usual miserable failure.
I even contemplated trying the ZAGI as it is intended, with elevons, with the giant vertical there but not active just to see what the takeoff might be like.
Maybe tomorrow if the weather improves.
Jan 02, 2013, 09:08 PM
Cognitive dissonance
kcaldwel's Avatar

I'm impressed you have ventured to try out this crazy idea!

I think trying it with the elevons active would be an excellent idea. If you could get it trimmed with the split surface slightly deployed, and then tried the drag pitch control at altitude it might have some hope of success.

I don't imagine it will be that effective for pitch control, particularly at low speeds. I would be interested to know how much elevon throw it would take to re-trim with it closed and fully open.

Last edited by kcaldwel; Jan 02, 2013 at 09:26 PM.
Jan 02, 2013, 09:58 PM
Ascended Master
Sparky Paul's Avatar
Kevin, way back in the olden days of escapement actuated rudder onlys, pitching with rudder was normal.
On gliding approaches, it was possible to flare for the landing by starting a turn in one direction, and rapidly clicking over to the other rudder deflection, with the plane flaring as it passed wings level because of the slight speed gain when pitching down with the first input.
Live Wires would do this well.
Some fliers would sweep the rudder hinge line back to get a bit of up-elevator effect when the rudder was deflected.
I have a few planes that pitch with rudder, usually noticed just before touchdown when feeding in a bit of rudder to correct the heading. My Stearmann was really bad this way!
I really see this as an exercise in self-satisfaction.. there's no possible way it could be practical, when there's well-proven aerodynamic configurations that don't need monster surfaces for routine control.
The radio I'm using is only a 3-channel, with no mixing other than selecting elevons, which re\quires a different servo plug-in configuration at the receiver than the drag-elevator uses.
Maybe a 6 or 7 channel transmitter might be programmable to switch between the elevator-elevon and the elevator-drag surface.

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