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Old Mar 07, 2013, 06:56 PM
person
derp express's Avatar
Joined Dec 2012
160 Posts
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Small, collapsible airplanes

Hey all,

I've been building foam airplanes using some of the building techniques demonstrated on ExperimentalAirlines youtube channel, i.e. the tape-laminated foamboard "Armin" wing, square tube fuselages, etc, and I have to say I'm very pleased with the results I've gotten so far, and even used several for FPV with good results between stability, handling and flight time. Currently, I'm in a job that involves a lot of traveling, so I'd really like to bring FPV capability to the places I go, so I want to build something collapsible and highly portable, capable of being carried in a decent size backpack, or a long padded case - perhaps something similar to what rifles are carried in.

Currently, my preferred designs are pusher configurations, due to the ability to provide an unobstructed view for FPV and/or video cameras for recording, like the go pro. So I had some questions for anybody who's attempted to design such a plane. Here are my design parameters:

-Wingspan no longer than 50 inches, must be collapsible into two pieces

-Detachable fuselage, fastened by rubber bands or other simple securing device

-Detachable vertical/horizontal stabilizer, also secured in place

-Unobstructed view for FPV/GoPro camera

Here are some of my proposed configurations:

The flying wing:

Pros: Huge potential for aerodynamic efficiency, high maneuverability, lower airframe weight, pusher prop provides unobstructed forward-looking cam

Cons: Payload/CG distribution very tricky, marginal longitudinal/directional stability, elevon coupling must be precise, or full stick-travel on the controller will cause an out of control condition

The canard

Pros: Reasonably easy payload/cg distribution, fairly stable with a lifting canard, allows unobstructed cam

Cons: Main wing operates in turbulent downwash of canard, canard has to stall before main wing to be stable, meaning the main wing might never reach full capability, also are most RC canard planes elevon-controlled, or is there a movable elevator on the canard? It seems like this would be difficult to do if the canard spans across the fuselage...both sides of the elevator would have to be coupled together somehow

The twin engine

Pros: Simple, conventional configuration, CG easy to set, payload easy to distribute, dual engines could mean higher acceleration, unobstructed camera view

Cons: Requires more wiring, and another ESC & motor = more weight

The conventional pusher

Pros: Simple, conventional configuration, except with a motor pushing at the very back of the fuselage, long distance from CG & AC means that vertical / lateral placement of engine has less pitching-moment effect, unobstructed camera view

Cons: I want to say this is the optimum solution, but I've found in building these that locating the CG at a safe place is very difficult without moving the wing aft on the fuselage, thereby shortening the moment of the tail, meaning you'd have to make a larger, heavier, draggier tail in order to have the same stability and elevator authority. If that problem could be resolved, this would certainly be my preferred airframe

The twin boom


Pros: Simple, and safe, like a conventional configuration, elevator is directly in propwash, giving you the ability to pull out of a stall or other bad pitch condition even at a low speed. I've made many of these, and I've been very happy with them. CG placement is easy, and it provides an unobstructed cam view

Cons: I use square wooden rods as booms, and I currently don't have a way to dismount them from the wing and tail section in order to be portable, so currently my only option is to glue them on the bottom of the wing. This is fine for small, light planes, but once they get into the 900g+ range, the structural loads will eventually separate the booms from the wing, causing a total structural failure in flight



I'm curious to know if any of you guys have built any of these airframe configurations, and what kind of luck you've had with them, or whether or not you have solutions to resolve some of the cons associated with them that I've run into. They all seem like great options, but I'm hesitant to adopt a new type of airframe until I know more about it. Also, if there are any suggestions for configurations you'd like to add, I'm very interested to hear them.
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Last edited by derp express; Mar 07, 2013 at 07:01 PM.
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Old Mar 08, 2013, 07:35 AM
An itch?. Scratch build.
eflightray's Avatar
South Wales U.K.
Joined Mar 2003
12,989 Posts
Don't forget kite wings, they can fold up and go in a tube, there isn't really a fuselage, just a frame for the motor and controls. Think parafoil and microlight style. The biggest object will be the transmitter.

Here's a very handy forum - RC Kites - http://www.rcgroups.com/rc-kites-723/
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Old Mar 08, 2013, 07:37 AM
An itch?. Scratch build.
eflightray's Avatar
South Wales U.K.
Joined Mar 2003
12,989 Posts
I was thinking something like this -

rc microlight
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Old Mar 08, 2013, 11:52 AM
Dragons, Windmills. All Same.
jcstalls's Avatar
United States, IN, Indianapolis
Joined May 2002
3,832 Posts
Carbon Falcon or type by acesim.com

No longer made yet a good used one can be found on at least this board.

Good luck,
Jared
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Old Mar 08, 2013, 12:32 PM
person
derp express's Avatar
Joined Dec 2012
160 Posts
Wow, that's some good stuff. I didn't realize kite-wings were used for anything other than free flight, but I suppose one idea that has good potential would be an FPV-parafoil. Very interesting
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Old Mar 08, 2013, 01:04 PM
An itch?. Scratch build.
eflightray's Avatar
South Wales U.K.
Joined Mar 2003
12,989 Posts
Here's another interesting one, using a kite and a vectored thrust control system.

There are quite a few using vectored trust.

MANTA - Vector Kite at Menden Kite Festival 2012
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Old Mar 10, 2013, 11:14 PM
Arizona Rim Country
Joined Nov 2001
492 Posts
Here's an idea for booms.
4" PVC UAV FPV walk around (16 min 32 sec)
at about the 12:15 minute mark.

Here's another thought http://www.acesim.com/rc/polly/polly.html
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Old Mar 17, 2013, 12:57 PM
Balsadustus Producerus
Escondido, CA USA
Joined Jan 2001
974 Posts
I've had a few models collapse at the abrupt end of a flight.
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