Do you think this would work? - RC Groups
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Feb 29, 2012, 01:25 AM
amidoinitrite¿ ¿
R31 Mark's Avatar

Do you think this would work?

Hey all, I want to make a 20" ish wingspan model of something like a Fokker DVI (I have the Walt Mooney plans for it). Anyway, I was thinking that maybe instead of the usual electric motor route of doing things I could make this a bit different. By way of powering it with a cox 049 or there abouts. But the real idea is this, I thought about what to use as a throttle servo and then all of a sudden I was hit by an idea, basically Flyzone playmate guts. But this is where it gets interesting, cut the motor wires and solder them to a servo, possibly one of similar size to the factory ones. But would it be strong enough to open and close an 049 throttle? and would this even work? I dont have much to spend ($100ish max), can anyone reccomend some cheap electronics that would work instead? So what are peoples opinions?
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Feb 29, 2012, 06:02 AM
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PeteSchug's Avatar
.049 is VERY BIG for a plane of that size even with a throttle.

Also, there is very little likelihood that the motor wires carry servo information.

MAYBE the input to the ESC has a servo type signal, but that's not guaranteed either.

I'd guess that something around 30 to 36 inches might be more suited to the power of an .049

All of the above is just my opinion.

Feb 29, 2012, 08:40 AM
MARK: I agree with Pete ... an .049 is way too big. More like a Cox TD 010 or maybe an 020.

But my biggest concern is going to a glow fuel engine, rather than electric. I flew all my ultramicro planes back in the '60s and early '70s using an 010 --- but, Man! -- the mess the exhaust made all over the plane ---- they're not called "slimeys" for nothing. Also once the plane's surfaces are coated (with even only a fine mist of fuel oil), and then there's crash damage that must be repaired, it's no fun cleaning all the surfaces with alcohol or other cleaner, to prepare the damage so it can be glued back together.

I admire your ambition to do a 'retro' but it ain't for me -- been there, done that..

Feb 29, 2012, 02:23 PM
Pilot, Co-pilot, Navagator
nemoskull's Avatar
keep in mind the cox .049 weighs more than the plane does once you figer in fuel.
i say go for it. but you will have a few critical problems here.
1. the oil in the fuel makes a slime on the plane that tends to eat paint.
2. you will need a pwm to ppm converter. homefly or bsdmicrorc has one, or you could go DIY.
3. a 049 is made for a plane in the 10 oz area, or about 290 grams.
4. a cox .010 is a better idea, but expensive. a cox 0.20 is good, but are a pain to run right. best bet is to buy one new, about 60usd. (still might not be any better.)
5. a cox .020 is mostly a low and hi throttle. assuming you have a exhast choke.

try posting on the cox engine forum.

if you really want to do this, scale the plan up to the 24-36 inch mark. keep in mind a cox .049 puts out a lot of thrust. you better off in the park flyer forum for this, tho.
Feb 29, 2012, 07:58 PM
amidoinitrite¿ ¿
R31 Mark's Avatar
Hmm wise words indeed. I think I'll go for a 020 if I can spot one on ebay. Mind if I ask what exactly a "pwm to ppm converter" is and what it does?
Feb 29, 2012, 10:36 PM
Registered User

They took the words ...

... right outta my mouth!

I'm with you, in so far as the whole engine v.s. motor thing goes (me, I like "internal combustion engines"), but they voiced all my concearns, burnt glow fuel is nasty stuff! A cox 1/4A engine requiers a lot of nitro too. It gets "all bad & ugly" in so far as paint & nitro goes.

Me, I'm switching to electric (although I hate it!), for just about all the reasons they brought up, I strongly recomend that you "make it easier on yourself" & consider E-Power too.

Well, there's my 2 cents worth,

Mar 01, 2012, 09:10 AM
Registered User
CorvetteC5's Avatar
I agree with the mess created by the fuel. I don't miss thoughs days

However, my first concern with this idea is the vibration from the engine over taxing the micro RX/servos circuitry and causing it to fail. Before I went all electric the servos would be isolated from the plane with rubber grommets, and the receiver was wrapped in soft foam. Not sure how effective these methods will be for the 1-piece brick proposed


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