View Full Version : Aviate your weeder
10-31-2002, 08:24 AM
Lots of small weeder/blower engines can be converted to commit aviation.They are cheap,reliable,and sip 87 octane at maybe 10% of the cost of slimer fuel.
The most popular are Homelite,Ryobi,and Echo,and any of these will convert toa unit that will turn a 16x8 or 18x6 in the 7000 range and power any 1/4 scale cub,a Sig 4/120,or the Dynaflite giant series to name a few with power in reserve.
No they wont challenge an RCS,ZDZ,Bison ,FP,3w etc etc etc but they cost about 20% of most of the above and can be converted by anyone with hand tools and access to a buddy with a lathe to do the little bit of machining involved.
We are fortunate here at RCC that we have among the regular contributors people who are hands on familar with all three of the above and would dive into any discussion on this subject or be pleased to help anyone who wants to give a conversion a try.There are strong opinions on various aspects of this subject,but regulars here at RCC have already learned to use difference of opinion constructivley for the common interest and arent going to get drawn into ego contests like some other sites.
I have noticed this subject to be of great interest on other net spots,soI will now sit back and await the avalanche of enthusiasm and questions. :lol:
10-31-2002, 09:55 AM
Just received a 25cc Homelite conversion engine a few weeks ago, from a guy down in Texas (GCBM engines)
The engine with a mount, muffler, prop adapter and "big bore carb" was $200 USD.
He claims it'll turn a 18x8 @ 7200 rpm. Haven't got the right tubing or stopper for my tank yet, hopefully this week end. I'll keep you posted on whether this engine will stand up to his claims.
If I'm repeating my post I appologise.
10-31-2002, 11:04 AM
I'd love to hear how it runs Chris. What are you going to be mounting it on?
10-31-2002, 11:34 AM
Chris.........I wouldnt be surprised if it did meet their claims,after breakin,and depending a lot on the prop used.There was a little action on the thread on RCU I think you were involved in and some new comments from your supplier.Is that $US200 before freight ,and conversion and application of our filthy taxes?Like $US 200 + frt x1.56x1.15=?
No criticism intended,I just like to keep track of buying vs converting myself.
10-31-2002, 02:32 PM
I'm mounting the engine on a 1/7 Brian Taylor designed Hawker Typhoon.
i sent him $217.50 Usd, shipping included. Then I had to give $16.00 to Mr. Chretien's cronies. :evil: All in all, for the hassle, I thought it was a good deal. I don't have the time to do it myself.
ya I was involved with that thread on RCU, actuallly I started it.
10-31-2002, 02:40 PM
aarrrgggghhhh drool.....I love the typhoon. Let us know how it goes. This sounds like a very interesting project.
10-31-2002, 02:42 PM
Dont the Feds also collect Provincial sales tax?
10-31-2002, 03:49 PM
Pictures taken with a crappy digital camera can be seen at
As I said to Jim McIntyre earlier, I usually don't give out that address cause it takes me 10 minutes just to write the address!! :D
looks like it will need 50 lbs in that short nose just to balance it.....!
10-31-2002, 08:10 PM
Plans call for a OS 120 and a pound of lead. I figured if i'm going to put a pound of dead weight in it , I may as well put a bigger\heavier engine in it. :idea:
10-31-2002, 08:51 PM
Kinda looks like a flying bail bucket with that big ol chin scoop. :lol: :lol: :lol: :lol: :lol:
11-01-2002, 05:33 AM
The Typhoon looks great Chris ! :D
11-01-2002, 07:36 AM
YOU had better hope it doesn't fly like a bail bucket!!! You're test flying it and checking me out on it!!!!! :D :D
Scotty's is a building supply outfit in Florida. Three years ago they sold hundreds of Homelite 25cc engines disguised as leafblowers for U.S.$48.00.
They ended up as optional engines for the G23, with a little more weight [flywheel] but for a lot less coin.
They are very easy starting, reliable engines and are loved by all. Good luck with the Typhoon!
Ward, Barrie ON
12-13-2003, 11:13 PM
check this thread out.
here are before and after pics of a chainsaw engine im converting..
it is a 32cc mcculluch... after removing all unwanted mounting metal, im left with the clutch shaft. i cut that as well cause all you use is the flywheel side.
here are pics of my 18cc weedeater engine. same idea.
12-14-2003, 12:10 PM
I also converted a Hom. 45cc chainsaw last year. turned a firewall to crankcase mount and the prop adapter. Cut most of everything off and turned down the flywheel and rebalanced it. I have run it up a couple of times with very little vibration and smooth response. Haven't flown it yet because I was worried about interferance at the strip. But it will fly in the spring and is mounted in my own Q1000 for sport. It was a fun project. :)
Thanks for the info on th 18cc conversion. Can't find your Sympatico site with the address stated. Kindly check spelling.
12-14-2003, 11:55 PM
i ran the 18cc on a test stand a few times....
i have a 14x8 2 blade prop.
now i have a 3 blade 12x8
the 18cc is not the best to convert, it's power to weight ratio is not very good.. aka to heavy for the thrust it produces
but, it was a very easy conversion. now for hte 32 chainsaw..
should have excelent power to weight... i dont have the flywheels machined... had it priced out.. would cost to much.. and you save minimal weight on it. as for the prop adapter on the 18cc... it's from a weedie.. so, the adapter that went from the shaft to the square drive shaft was easy to make into a prop adapter.. i just tapped the threads thru the adapter. the 32 does not have an adapter to work with cause it's from a chainsaw.. i'll have to either order one or get someone to make one out of aluminium stock.
12-15-2003, 12:10 PM
There is a big range in displacements and power available for conversion, from tiny 16cc weedeaters to big chainsaws. Where do you start, in selecting a prop? Has anybody made any sort of a prop selection chart, like for the glow engines? These big props are a little expensive for trial-and-error, especially considering we're trying to save $ by doing a conversion, instead of buying.
12-15-2003, 12:13 PM
on my 18cc i t was recommended at 14x8
i read alot of forums and threads... most ppl see to run 18x8 om large weedies... 25cc and up.
also ppl seem to use props that will give them 6000 to 7000 rpm.
i would love to find a chart like that bIG-H!
if anyone has one.. please post i!
12-15-2003, 05:57 PM
I've converted a 31cc Ryobi (flywheel ign.) using a "Tillotson" carb with the "choke area" enlarged to .410".. Engine turns a
Dynathrust 18x8 prop at 7400 rpm.and idles at 1900 rpm.
The "transition" is smooth but not "lightning fast".. It hauls a Sig 4*120 with "authority" doing all the "basic" IMAC maneuvers. Even the "verticals" are respectable, but of course, not "unlimited". :)
12-15-2003, 09:28 PM
I think you can look at what is recommended for a similar displacement gas engine (prop that is) and go from there. For example:
30cc - 18-8 to 20-6
40cc - 20-8 to 22-6
50cc - 20-10 to 22-8 or 10
60cc - 22-10 to 22-12, 23-10
70cc - 24-10
This is a rough guide based on my own experience and what was recommended for some of my gas engines.
12-16-2003, 07:18 AM
I dont like to wind my gassers as high as some so I tend to use somewhat larger or higher pitch props than Andrew for example.
30cc..............Try 16x8 if you have a tip clearance problem which often will happen running a gasser in a 1.20 size model.
The type of model has a bearing too.......
Model prop will make a difference.........scimitar blades will rev higher,paddle blades will run slower but quieter.
The main thing is not to get all bent out of shape worrying about props.....get one in the ranges in this thread.Balance it well,snug it down now and then,check it for damage and balance every time you ding the field.Fly the varnish off it ,and when you break it try a slightly different combination and see if you can appreciate the difference.Soon you will develop your own opinions.
If you find too many $ tied up in props,clean em up and take em to a swap meet.........
12-16-2003, 11:20 AM
Yes, or look at swap meets for props too! :)
Or, start carving your own... ;)
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