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Old May 09, 2012, 06:28 AM
Registered User
Ireland
Joined Dec 2005
16 Posts
Discussion
Building a plank on a tiny budget.

Recently I got a fit of building rc planes which I have not done in years.

It was actually a video of the Alula which got me thinking so I hacked some epp I had laying around in an alula shape.

Very quickly it became apparent that radio gear was going to be the main problem/cost. I prefer problem as I find it easier to solve than cost.

So I needed elevon mixing, dual rates and light gear.

Light gear no issue. I had a battered Esky lama which gave up a 4ch Tx and tiny rx with servos.

After lots of internet hunting it became clear that the only free way to solve the other problems was to mix mechanically.

I went for the hinged aileron servo method. This works great as you dont need the dual rates and also you get to keep full (poor) resolution.

So anyway that is one way to get elevons for dirt cheap. I also included a picture of a similar setup with the aileron servo sliding on some paperclips. This is better in terms of slop.

I am aware that if you bought all this gear you would be better off getting the right gear but if you have some stuff laying around that you thought was useless this may help you. There are a few posts on here and youtube videos about these methods but I couldnt find anything suited to such a small plane.

The other method.

So then I rigged up a hotwire and cut some wings for a kind of maxi weasel mini wildthing plank. I used the general proportions/sweep from speedsterdens wisel with the bluto root profile. It cost 2 in foam (eps) but a whopping 6 in tape so I figured I was in pretty deep so I better buy some rc gear for this one.

I know 2.4g is cheap now but by the time you get something with mixing and rates plus rx and servos and bit of wire it adds up to more than I had laying around.

So i I bought cheap gear for the plane with an onboard mixer. the whole lote with horns clevises ext. cable to make a charge jack etc was 30 euro from giant cod with shipping.

Now i had mixing and a new plane with all new gear (a first) but I knew I didnt have a hope with full elevator throws.

This is my only problem with this forum. I couldnt believe the amount of threads where someone asked a question like "diy mixing" or "homebrew dual rates" only to be met with it cant be done or just stump up the cash. The worst is when you then find out later that it can be done. Surely this is a hobby where we do this kind of stuff. So maybe you like to buy boxes and plug them into each other and they work with no messing around. thats fine, but if you dont know for certain why tell someone that something cant be done.

rant over

I searched for ages here looking for a diy dual rates thread but it is apparently impossible. Until you search car forums. those guys would wire a friggin kettle to there tx if if got them dual rates or servo reversing.

http://www.tamiyaclub.com/forum/inde...howtopic=12992

If you go to that link and scroll down like 5 posts there is the worlds simplest circuit diagram. Follow it and you have lovely variable rates. the pots required can be taken from another tx.


so the onboard mixer is two pounds on giant cod and the rates are at most the same if you have to but the pots.

I have been hooning this thing off of and into mountains and it works great. super easy to adjust rates on the fly. This may not be your bowl of apple but if, like me, you want to have some fun for little cash then this may help you out.

I also included mi indestructible tail mount if you are interested.
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Old May 09, 2012, 09:00 AM
Registered User
Denmark
Joined Sep 2008
186 Posts
Clever and simple solutions there. Thanks for sharing. Not everybody can (or want to) buy their way out of every little issue.
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Old May 09, 2012, 06:26 PM
let's FLY!
JimZinVT's Avatar
United States, VT, Castleton
Joined Dec 2007
2,295 Posts
I love stuff like this. Some of us are doing this on a tight budget. Nice idea for the tail mount.
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Old May 09, 2012, 09:18 PM
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Hawk I's Avatar
United States, CA, Cerritos
Joined Feb 2010
112 Posts
Love the sliding servo idea!
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Old May 10, 2012, 03:11 AM
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Xpress..'s Avatar
United States, CA, Alpine
Joined Oct 2007
21,001 Posts
That sliding servo is ingenious.
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Old May 11, 2012, 08:13 AM
Registered User
Ireland
Joined Dec 2005
16 Posts
thanks for the positive comments

if you have computer radio the mech. mixing is still good because of the full servo resolution.
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Old May 14, 2012, 03:01 PM
Registered User
Ireland
Joined Dec 2005
16 Posts
i flew this in 20-30 kts yesterday and had no issues at all with radio range/resolution etc.
I am a huge epp fan but trying to get the stuff in Ireland basically means importing it.
I am pleasantly surprised by eps wrapped in tape. i have clattered it off the (rocky) slope a few times and its still happy.

Also I forgot to mention spars. i used a 5mm fibreglass rod from a cheap stunt kite.
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