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Convert a old r.c. wing to c.l.

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Old 02-12-2012, 07:11 PM
  #1
flyingagin
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Default Convert a old r.c. wing to c.l.

Just want to run a feasibility and practicality question by you guys.

I have an old r.c. wing that I picked up a long time ago. It looks similar to a stick .40 wing. 50” span and 10.5 “ chord, With the ailerons making up 1” of the chord. It looks to be about an 18% thick symmetrical airfoil.

I am thinking of converting it to a c.l. with a OS. .25 bb r.c. for power.

I would cut the center out and rejoin to remove the dihedral. That removes 4” of span. Should I also remove a rib bay each end to further reduce span and area?

Since the t.e. is already hinge should I add flaps? Does 1.5” sound right?

So these changes would yield a 42” span and a chord of 11” for a total area of 462” square”.

A box fuse would be easy and fast to build. A stab of 100” to 120” square” about 12 inches from the wing t.e.

Do these numbers seem right?

The idea is to finally put this wing to use and I need a fast build c.l. for my spare engine.

I want to fairly aerobatic, no need for competitive.

I don’t have a bigger spare engine that I can use. So that sets the limits.

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Old 02-12-2012, 11:11 PM
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Default RE: Convert a old r.c. wing to c.l.

Sounds good to me. I think 100 squares on the stab would be plenty for your wing area. The ailerons now there could well suffice for the aerobatics that you plan.

Are you going to use the RC Throttle locked open or do a 3rd line or electric with insulated line for throttle control?

Good Luck!
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Old 02-13-2012, 06:18 AM
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Default RE: Convert a old r.c. wing to c.l.

Hi Hossfly
I will throttle it but not with a third line even though I do have a J. Robart's handle and the belcrank for it. But that is lots of extra line drag and wight on the inboard side.
Not enterested in competeing with it or any thing. Just a fun cheap plane, fast to build.
Does 12" sound right between the wing t.e. and the stap l.e.? Or should I go for a longer tail moment arm? When I was young we would lengthen the tail of Magicians about 2 inches if they had flaps. So I am wondering if the tail is long enough.
Once I start I will do a build thread.
Because of storage and transport limits I am going to make the wing removable.

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Old 02-13-2012, 12:09 PM
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Default RE: Convert a old r.c. wing to c.l.


Quote:
ORIGINAL: flyingagin

Hi Hossfly
I will throttle it but not with a third line even though I do have a J. Robart's handle and the belcrank for it. But that is lots of extra line drag and wight on the inboard side.
Not enterested in competeing with it or any thing. Just a fun cheap plane, fast to build.
Does 12'' sound right between the wing t.e. and the stap l.e.? Or should I go for a longer tail moment arm? When I was young we would lengthen the tail of Magicians about 2 inches if they had flaps. So I am wondering if the tail is long enough.Once I start I will do a build thread.
Because of storage and transport limits I am going to make the wing removable.
Man, you surely ask hard questions. My only nswer is that if the CG is within the 20 to 27% range the machine will fly. I am a member of PAMPA, so I get STUNT News, and I subscribe to Brodak's Control Line World. I see all kinds of tail feather, big to small, all kinds of moment arms and they ALL FLY.[8D]

When I came back to the Republic in 1985, I built a flat bottom all balsa wing of about 7" chord and 36" span. I made a profile fuselage with the engine mounting upright but a tad long to get tank, etc. all in place. Using an old Fox 19, it was way nose heavy. The tail moment was about 3 times the nose moment. I added a lot of lead to the tail but the CG was still at about 15%. It took off and flew around very well. It would do a big loop and a wingove OK, along with BIG lazy eights. No squares so that they could be called square.
I played with it with grandkids for years as I could fly 52' lines in the backyard. It was almost impossible to get a good landing as the stab was small and with the very forward CG the nose could not be held up enough for the needed low landing speed.

Now 27 years old, same Fox 19, I recently revamped the nose and got the engine moved back by an inch. That allowed a bit of tail weight to be removed. Cg is now at 23% of MAC. It takes off great, flies very smooth, tight loops and fairly tight corners long way from competition but much better than before landings are a dream. Even with the flat botrtom wing, lazy eights can be done but rather larger on the outsides.

The only thing I know for sure is that 20 to 30% is a reasonable CG Range. All my RC start at 25%, which is very much against the 30-35% the ARF RCers use and crash a lot. []

Your 12" should work very well if you keep the CG as close to 25% MAC as you can. It is always better to start nose heavy and then gradually move back, if you just must.
Back when I was much younger, and flew the Boeing B-47, a definite suicide was to start a Takeoff roll with a CG aft of 35% MAC. Easy to do if you had no load in the Bomb Bay and/or the forward aux. fuel tank was less than full. It only had a tab indicator, Full, intermediate or empty. The only way to check was to climb the ladder, open the cap and LOOK. I have seen so many RC Warbirds die on TO when the pilot followed the kit instructions and used 33% for a first TO. It happens in CL also. Sad!

flyinagin, you will do just that as you seem very strongly in keeping the colors between the lines!
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Old 03-12-2012, 09:38 PM
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Default RE: Convert a old r.c. wing to c.l.

If there is a will, there is a way.

Problem with control line planes is none of them are light enough, just ask any builder.......

Anytime you start retrofitting and modifying stuff, you inevitably will end up with something that is heavier than a comparable plane that was built for the purpose right from the get go.

That being said, go ahead and partake what this hobby is supposed to be [at least in my mind]...a place to try things and see what comes of it.
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