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Feb 03, 2010, 08:51 PM
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Discussion

3D Hobby Shop 57" Extra 330 SC Glow Conversion


First Let me say I am new here on Rc groups. So Hello everyone!!!
I saw a video of one these with a saito already but I didn't see a thread on the conversion yet. So I figured I'd post mine.

This is my first aircraft from 3DHS and I am very impressed! Excellent quality, construction, and customer service!

But I am the type of builder that can't leave good enough alone so i always tweak a model to my taste. And i like to experiment with a lot of techniques. So i made a few changes with hardware and setup to keep the airplane lite.

The goal when I started was to build it on Glow power and have an AUW equal to or lighter than the electric setup. If I built it according to "tradition" would definately be much heavier than the Electric setup.

Equipment used.....

OS 55ax
Perry Pump
Macs Tuned Muffler
6oz "bladder" tank
Hitec 225mg ail, elev, rudd
Futaba s3114 throttle
800mah lipo (reciever batt)
Hitec FM reciever
Mpi voltage reg

So I made a lot of modifications to the hardware to keep weight down and parts stronger

Some of the modifications
Lite weight wheels
Modified the stock elevator carbon sleeve to work without the heavy metal rod in it.
Kevlar rudder cable
Modified tail wheel set up

Was able to balance without adding any weight.

Auw without fuel is 4lb 7oz
with fuel is 4lb 11oz

Was able to put tank almost directly over cg so almost no affect in cg as fuel is depleted

I also made my own bubble less "blader" tank using a condom
so there is no heavy clunk in tank. and just one line from tank to pump to carb. I wasn't sure how well it would work, but so far it is working better than expected!

Here are some pics of the Motor mount. I tried to incorperate the stock mount for the electric motor. This was an attempt to keep the weight low and keep it strong. All wood was laminated with .25mm carbon fiber. And the the walled off with 1/32 balsa sheet. then fuel proofed
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Feb 03, 2010, 08:59 PM
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Pics of the Fuselage bay and main and tail wheel
Feb 03, 2010, 09:05 PM
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Here are some pics of the cowl. Enlarged the opening in cowl to allow plenty of air for engine cooling. Also have few pics of first few flights
Feb 03, 2010, 09:23 PM
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Video of engine running and smooth idle
100_2379.MOV (2 min 13 sec)
Feb 03, 2010, 09:31 PM
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As for flights, I have eight so far. With the 6oz tank I am getting close to 10 min flights, with out completely draining the condom I am keeping a close watch to see how long I can go before it needs replacing. If it ever will.

The performance is nothing short of amazing Locks in hover very well. Rolling harriers are effortless, same with both upright or inverted. Have to hold a little aileron in to keep spins flat and from rolling out. And it so easy to get outta trouble with the low wing loading!!!!

I will try to get flight video up soon.
Feb 10, 2010, 03:06 PM
Perfect 3pt inverted landing!
teookie's Avatar
What you have done with the fuel tank is genius, I think. Put any more flights on it? How's it holding up?
Feb 10, 2010, 06:16 PM
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Thanks, Well now i habe about 13 flights on it. seems so be holding up well. and throttle response is near perfect. I am thinking of pulling it out and inspecting it after 20 flights. If it looks good, I will prob change it every 30 flights or so for safe measure. It is realy easy to remove tank and change it. prob less than 5min.
Here is the video I made recently. not the best qaulity filming but enough to see it's performance.
Kelvin flying video 2.wmv (8 min 25 sec)
Feb 15, 2010, 08:36 PM
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That is freakin cool!! Nice job It's such a cool plane, and to be running nitro is even cooler
Aug 09, 2016, 12:44 PM
Registered User
Thanks for the great post KW! I bought the same plane last week. I'm going to do the same conversion as you. What size prop did you use on the 55AX?


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