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Old May 28, 2015, 03:53 AM
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SPAD control horn and torque rod connectors

Apart from electronics and piano wire, the only things I still regularly need to buy from a hobby store are the plastic fittings used to connect push rods to torque rods and those really nice little adjustable fittings for connecting push rods to control horns (I see they are called linkage stoppers). These are the two items I normally use:
http://hobbyking.com/hobbyking/store...mm_10pcs_.html
http://hobbyking.com/hobbyking/store...0pcs_set_.html

Neither are particularly expensive, but they are often out of stock and I always seem to be running out...so have for some time been wondering if I could use cable connectors to substitute them. The pictures show what I have done

The first method should work just as well for aileron torque rods.

The last picture shows how I have replaced the linkage stoppers with cable connectors. I was initially concerned about the movement causing the rear screw to come loose, but so far I've had no problems. You could also add some wood glue to the thread to have make it 100% safe.
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Old May 30, 2015, 03:49 AM
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Originally Posted by Extreme Sports View Post
Thanks for the compliment, but I only build for myself. IIRC, the F16 took the better part of a week to complete, so it's never going to make financial sense to build for others.
I really want an f-16, could you possibly make a youtube on constructing one ?
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Old Jul 11, 2015, 04:47 PM
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Hi all. I'm planning a two piece wing approx 1500mm wing span soon.

As always, trying to keep weight down so was planning to go with 3mm correx doubled and CF strip or rod for spar. Strong enough?

This will be my first attempt at using nylon bolts to mount wing too.

Question is: what's the best way to join wing halves considering weight saving and bolt mounting wing? I assume some sort of spar sleeve and wing wrap? I might go with some dihedral as well. I see ES in your chipmunk photos you have a foam wedge in the centre of leading edge as well?

Any advice welcome. Thanks.

E.S. Some more great ideas/techniques on this thread over the last 6 months I've been away...
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Old Jul 13, 2015, 08:33 AM
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By 'two piece wing' you mean a conventional correx wing with a top and bottom skin folded at the leading edge, or one that can be separated into two pieces to make it fit into the car?

If it's the latter, I've not ever tried to build a joinable wing, but it's been done by balsa builders for years, and I'm sure their technique will work fine on correx - i.e. one or more rods that fit snugly into corresponding tubes. I think they use brass tubes and piano wire, but you could use CF or GRP rod - just wrap and glue thread or similar around the tube to prevent it from splitting.

For a 1.5m wing I'd still use 2mm correx if available - it's more than strong enough. I've been thinking of building something around 2m and for that I would still use 2mm. Several of the sloper designs are close to 1.4m and they all use 2mm wings. Some guys have enlarged the slopers to 3m spans, but I think they did step up to 3mm correx for those (I would still try 2mm...).

Regarding the spar, you will need at least a 6mm CF/GRP rod for strength plus foam or balsa to get the depth of the spar, and then some anti-crease strips. I'm busy with a 1.4m Vulcan and this is what I have used. Bear in mind that as you build larger, weight is not nearly as critical a factor as it is for the smaller designs, so even a shaped plywood or thin pine spar will probably be OK. If your wing is a simple constant chord (I.e. un-tapered) you could even consider running the flutes span-wise, which will increase the wing strength and give a nice round leading edge. That is what I have in mind if I ever do the 2m span build.

What is the plane you have in mind? For example, the depth of the wing is a big factor in how I would build it - if its deep, I'd go for a light GRP and foam spar with the flutes running span-wise, whereas if it's quite a thin profile wing, I'd run the flutes chord-wise and rely on a strong spar for rigidity.

Regarding the bolt on wing, the foam you see is to stop the bolt from crushing the wing profile. I also reinforce the area around the bolt hole with thin aluminium/ thin ply or even the plastic from an ice-cream tub. The chipmunk was a bit unusual in that the bolt is at the front...its generally easier to have a dowel in front and the bolt at the back (just be careful that the bolt does not foul the aileron torque rods)
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Old Jul 13, 2015, 04:24 PM
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Thanks ES.

Yes I was referring to a two piece wing to fit in car but a simple removable wing would do too I guess and simplifies the build for me. Would like to give it a go at some stage tho.

The plan is to build my father a powered glider. I've already built him a mugi sloper.

I initially wanted to scale down the 2.3m Big bro twin boom pusher glider but decided I need a simpler build first try.

Instead, considering converting the balsa "Thermal Charger" to corflute (See plans attached) but with a conventional tail perhaps.

My initial calcs for a 1500mm WS design of this type with a 28gm motor and 1300mah lipo is easily achieving glider type wing cube loading and that's using the 2.5mm corflute I have here which is 390gsm approx.

I'll need to make other tweaks to plan no doubt but a nice simple fuse to start with. I'll even give the polyhedral a go I think and add ailerons with servos in wing.

Chord appears to be approx 240mm so a typical glider aspect ratio and slim profile

Whaddya think?
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Old Jul 13, 2015, 04:34 PM
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Thermal Charger

Here
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Old Jul 14, 2015, 12:16 AM
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That is a very thick and low aspect ratio wing for a glider. Should have no difficulty with a spar, even a strip of nylon strapping tape glued under the skins at thickest point top and bottom would do.
A thinner foil would give better penetration and less drag but i know that without ribs or solid core, adhering to a known foil like a Drela is difficult. Not important in a sloper but a limiting factor in a successful thermaller.

Attached an electric version of the CorroBat sloper that has details on wing construction, and see Bex's posts on his gliders, eg: http://www.rcgroups.com/forums/showthread.php?t=1143190
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Old Jul 14, 2015, 02:44 AM
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Ah, a glider!

Agree with RN - that is probably not the most efficient glider wing about, but at least the thick profile will aid strength. Here are a couple more thoughts:

1) PM TrevorJS and ask him to chip in here - he built a Fox in correx and I remember he did quite a bit of experimenting before he was happy with the wing.
2) Any reason why you are limiting yourself to a 1.5m span? Even more so if you are planning a two piece wing, which will add more non-lift generating weight. 1.5m is pretty small for a glider, even a light foam one. Certainly too small to justify splitting the wing. Why not go to at least 2m?....at that size the weight penalty of correx starts to be come less of an issue relative to other construction techniques.

Just over a year ago I built a very simple twin boom pusher with a simple folded 1.6m (IIRC) glider style polyhedral wing. It sort of flew like a glider, but definitely was on the heavy and fast side, with a correspondingly high sink rate. I'm sceptical that a relatively chubby design such as the Thermal Charger will fly all that well at just 1.5m span (be great for a slope though). Of course, I am happy to be proven wrong - this thread is all about seeing where the boundaries lie
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Old Jul 14, 2015, 04:56 AM
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Originally Posted by Rusty Nail View Post
That is a very thick and low aspect ratio wing for a glider. Should have no difficulty with a spar, even a strip of nylon strapping tape glued under the skins at thickest point top and bottom would do.
A thinner foil would give better penetration and less drag but i know that without ribs or solid core, adhering to a known foil like a Drela is difficult. Not important in a sloper but a limiting factor in a successful thermaller.

Attached an electric version of the CorroBat sloper that has details on wing construction, and see Bex's posts on his gliders, eg: http://www.rcgroups.com/forums/showthread.php?t=1143190

Thanks Rusty Nails

I hear you re wing thickness. Always intended to reduce profile a little and realize it's not going to be a thermalling bird.

Basically just want a crash resistant pusher that my old man can motor to a decent height and glide back down. A true thermal bird can be the next project if at all. I guess the model name is pretty inaccurate and misleading, sorry.

The Corrobat pdf is excellent thanks! I have the RC Soaring Digest article on the unpowered version and have referred to it on numerous occasions. Love it.

Finally, the 3m giant from Bex is amazing, thanks for link. It's funny, his spar joining idea for removable wing is exactly the way I envisaged doing it myself. Nice to know I may have a coherent thought occasionally!

Thanks again.
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Old Jul 14, 2015, 05:19 AM
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Originally Posted by Extreme Sports View Post

1) PM TrevorJS and ask him to chip in here - he built a Fox in correx and I remember he did quite a bit of experimenting before he was happy with the wing.

2) Any reason why you are limiting yourself to a 1.5m span? Even more so if you are planning a two piece wing, which will add more non-lift generating weight. 1.5m is pretty small for a glider, even a light foam one. Certainly too small to justify splitting the wing. Why not go to at least 2m?....at that size the weight penalty of correx starts to be come less of an issue relative to other construction techniques.

Just over a year ago I built a very simple twin boom pusher with a simple folded 1.6m (IIRC) glider style polyhedral wing. It sort of flew like a glider,

Thanks ES

YES, I've been following the Foxx build, and the Eagle X (love it but no plans as yet - and I really need a plan…) and even the U-2 Spy plane! All great builds.

So guess you're right, I should probably go with larger wing span and as you say, then worth making a two piece wing, although I'd pretty much discarded the idea of wing split at 1.5m. I do however like the simpler build of the Charger and fact it's a pusher ( for crashability ). Scale the Charger up? Dunno.

If I open it up to tractors, heaps more choice I know.

Maybe I should finish that Plastic Polaris, get the build skills up and move on to a Foxx!

As always, thanks for the advice guys.

P.S Whilst I was considering a twin boom pusher, I recalled your version and almost asked for the plans…
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Old Jul 14, 2015, 08:13 AM
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I must admit that I am in two minds about pushers. With the exception of the small pusher trainer on your other thread, all my pushers have been a bit disappointing. Two reasons:
1) The prop clearance issue means that one has to use a small diameter, higher rpm prop, which does not match the high thrust at slow speeds requirement of a beginner plane.
2) The high mounted motor and the prop wash effect require trim adjustments whenever the throttle changes, which does not make for relaxed flying.

To some extent I solved them in the pusher trainer by mounting the motor inside the fuselage, and on the twin boomer with a centrally mounted motor and inverted V tail. But I am still not sure if I achieved much more than can be done much more simply with a prop saver on a conventional tractor set up.

But give the scaled up Charger a try - after all it will only cost you a bit of correx and I am sure you will learn something new.
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Old Jul 16, 2015, 05:42 PM
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Thanks ES. noted.
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