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Author Topic: SFG = Side Force Generators  (Read 712 times)

Offline Ron King

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SFG = Side Force Generators
« on: September 23, 2006, 07:05:01 AM »
Dean Pappas raised this idea over on the Electric Forum, so I thought I would bring it over here and see what the design people think.

Side Force Generators (SFG) are widely used in the RC world, especially the 3D planes. They help with knife edges and the other maneuvers that force the airplane to use its fuselage for lift.

We have several maneuvers that could possibly use this type of help, plus our entire event relies on centrifugal force to keep the plane out on the lines. The thought of adding SFGs to the model could possibly allow us to slow our planes down more and still maintain enough line tension to perform good maneuvers.

Has anybody tried these already?  How well did they work?

Ideas?  Pro or con.

Ron
Ron King
AMA AVP District 4
Wannabe Stunt Pilot since 1963

Amateurs practice until they get it right;
Pros practice until they cannot get it wrong.


Online phil c

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Re: SFG = Side Force Generators
« Reply #1 on: September 23, 2006, 08:13:59 AM »
I did a side force generator experiment of sorts years ago.  I built a profile Wildcat with a scale fuselage- 7 in. high no less.  Once it was trimmed properly I didn't notice any real difference or improvement from the extra side area.  In a strong wind it would get blown in a couple feet on the upwind side.  All that side area doesn't just go away when you don't need it.

About the only place extra side area might help is in the overhead eights.  There we seem to be better off just making sure the plane is square on the end of the lines to minimize speed loss.  Keeping the speed up keeps the centrifugal force up.
phil Cartier

Offline Steve Fitton

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Re: SFG = Side Force Generators
« Reply #2 on: September 23, 2006, 08:19:04 AM »
I think Doug Moon tried this already, with very poor results.

The closest to a side force generator I've seen might be the tall forward set canopy on Russian F2B ships, or the big. tall forward set canopy and turtledeck of Stiletto or Patternmaster, etc, ships.

I would guess that the aoa of the R/C side force generators when in knife edge flight is much more than the aoa a C/L plane could present , so they may have minimal effect in C/L maneuvers, but present alot of sail area for the wind to disturb the model.


Steve
Steve

Offline Dick Fowler

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Re: SFG = Side Force Generators
« Reply #3 on: September 23, 2006, 10:53:09 AM »

Doesn't rudder offset create about the same effect? 
Dick Fowler AMA 144077
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Offline Terry Fancher

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Re: SFG = Side Force Generators
« Reply #4 on: September 26, 2006, 04:03:14 PM »
My first WC experience in Sweden in 1982 was also (I believe) the first year the Chinese fielded a team.  They were very, very good already and placed second as a team to the US trio.

At least a couple of their airplanes used a form of side force generator.  In their case it was an airfoiled "tip tank" sort of appendage to the outboard wingtip.  As a source of tension it made much more sense than offset rudder, for instance, because it acted sideways to the flight path rather than yawing the fuse sideways which is a very poor way to attempt to generate tension and counterproductive in almost any other aspect of flt trim.

Don't know whatever became of such devices as the next time I personally saw the Chinese airplanes was in Shanghai in 1994 and they had by then redirected their attention to much more conventional layouts (still equally competitive, of course).

Ted

Offline Ron King

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Re: SFG = Side Force Generators
« Reply #5 on: September 27, 2006, 05:51:57 AM »

At least a couple of their airplanes used a form of side force generator.  In their case it was an airfoiled "tip tank" sort of appendage to the outboard wingtip.  As a source of tension it made much more sense than offset rudder, for instance, because it acted sideways to the flight path rather than yawing the fuse sideways which is a very poor way to attempt to generate tension and counterproductive in almost any other aspect of flt trim.

Ted

Thanks, Ted. This is exactly what I was picturing in my mind. Sort of like the tip tanks/extensions we see on some of the bizjets that also squelch wing tip vortices.

I'm not sure if these would help, but am also not sure if they would hurt, either. I guess it all depends on how much weight and extra work they create.

Ron
Ron King
AMA AVP District 4
Wannabe Stunt Pilot since 1963

Amateurs practice until they get it right;
Pros practice until they cannot get it wrong.

Offline Dick Fowler

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Re: SFG = Side Force Generators
« Reply #6 on: September 27, 2006, 06:18:48 AM »
Disproved my own theory... Never Mind!  :)
Dick Fowler AMA 144077
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Akron Circle Burners Inc. (Note!)
North Coast Control Liners
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