I'm thinking 20cc+/- for this twin SkyMaster.

http://www.internet-rc.com/ces02abskymb.html

I've been wanting to build this plane for YEARS, but I can't bring myself to buy 2 glow engines.[:'(] I'd be much happier with a couple little conversion engines on this plane.

Any ideas on what motors to get for it? I was looking at the Brillelli 25GT Toro engines, but I think 2 of them will tear this plane apart. Something smaller.

Thanks

A 13 lb. airframe is not likely to be strong enough to support two gas engines.

Bill

Why not?

I can build reinforcement into the firewalls and fuse sides if needed.

A 120 4-stroke glow engine weighs just a bit over 2 pounds. Scotts 25cc Toro weighs only 3.5 pounds. I can't see why a 20 or 21cc engine wouldn't be a bit lighter than that. Maybe 3 pounds if I could find a nice, light engine.

You saying an airframe with 87" of wing won't support an additional 2 pounds worth of engines? I could use little 8 or 10oz fuel tank. I'll bet the overall weight gain over 120 4-strokes would come out to about 1 or 1.5 pounds. That airplane can handle that much--no problem.

Anyone know of any small gassers--not too heavy--that I could put on this plane?

if you can find the little shindiawa I think 23cc or 21cc engines they are 2.5 lbs each with a muffler and my lightened flywheel I will post a pic. later. I am puting one of these on a 96 in monocoupe.

Darin

I just looked at the pic. of the plane and I think you might have a clearance issue with a magneto flywheel and cowl.

Darin

Your also going to have to find the appropriate size pusher prop for that rear engine.Both engines will be turning the same direction (C.C.W)when viewed from the front of each engine.Your probably going to have to use a CH type ignition system on these engines and do away with the magneto because like was mentioned already,I don't think your going to have the cowl clearance,unless you set back the firewalls a bit and use a much longer prop hub adapter.They would have to be custom made no doubt.Any other way would have the cowls so chopped and modified,it would just end up looking dorky.

I'll be using electronic ignition to try and save weight.

I know that you can make a Ryobi run backwards if you just put the hall sensor on the opposite side and flip it backwards. But, thats only because it's a reed induction through the backplate. I don't think you can reverse the operation of a piston ported engine--I could be wrong.

I really don't see a need to run 1 engine reversed on this plane. With both engines running in the normal direction--torque will be canceled out. Thats the beauty of an inline twin.

I'm checking into the threads that discuss gas/glow fuel combination--where the engine is run on a glow plug and no magneto or coil. Thats would be light, and no magneto to interfere with the cowls. I'd prefer C&H and run regular gas 40:1 mix--but I'll do a gas/glow hybrid if I have too.

That sounds good. Have you tried one on C&H? Lightweight is the key here. Of course, glow is the lightest--also expensive to purchase when compared to a conversion engine, and messy as all get out.

Possibly 2 Echo/Kioritz ,,,hmmmm they were either 16 or 18cc engines. Conversionists sometimes discard these because of the power to weight issues,,but they just might be the ticket for your plane. Converted to EI they should be light enough and I see that plane only calls for 2 .91 4 strokers.

It will be a miracle if you get an airframe designed to fly on two .45 two stroke engines reinforced sufficiently to accept gas engines.

However it is your money and your project.

Bill

91 4-strokers would struggle get this plane off the ground up here in Colorado. If I were to use glow--I'd have to put 1.20 4-stroke engines on it. It might be just a tiny bit too much power--but I'd rather fly it at 1/2 throttle than worry about getting it off the runway everytime I attempt to fly it.

Thats why I think an 18--21cc gas engine would be just about right.

here you go

if you run (gas/glow hybrid) you can get these ready to fly at 2 lbs. no problem I would love to help you out on this project. If you need any custom work let me know. I think you are on the right track, dont give up on this.

Darin

BN120:
Where'd did you find those engines? Are they the Shindiawa engines you talked about earlier?
Weedeaters? Leaf Blowers? What brand of machine are they usually in--i.e. weedeater, poulan, yard machine

I'm going to need a prop hub, and maybe some other machineing. So, I'd love some help, thanks. Of course, I'd pay you for the help and machined parts. Not looking for a free ride.

I can't buy the plane untill I figure out the powerplant. Otherwise, I'll have a plane that will never fly--'cause I'm not using glow on it.

Now, where do I find those little jewels?

This is looking better and better all the time.

Have you ever heard the old saying, "If you don't have something nice to say, don't say nuthin' at all." ?

I've got some guys here willing to help me dig up the right motor. BN120 has offered to help with machineing. This can easily be done with motors that weigh under 3 pounds.

I'm guilty as anyone for saying stupid stuff and makeing comments where I should just mind my own business. It's something I'm working on. Trying to only comment when I can help in a positive way--or I have had the plane/engine before and know what I'm talking about. It's a work in progress, but I'm aware of it and trying to get better about it.

The Skymaster Twin has been a dream of mine since I started flying. Almost 8yrs ago. It's the same as a guy who builds a scale B-17 or a 30% Cessna 182. It might not be perfectly 100% scale, and it might be a little overweight, but It's my dream man. I'm in love with this plane. Quit trying to squash my dreams man. Your killin' me.

Back to these engines:
I'm all over the internet looking at 18 and 21cc engines. I haven't found a Shanindiawa yet, but weedeater makes a 21cc engine

the newer one is a c230 trimmer the older one is a couple ounces lighter and it is also 21 or 23cc b ut I dont know the model #

Two old style G23s with all the extra stuff cut off, using aftermarket ignition, would work..We flew a 110 lb, 16 foot wingspan DOX seaplane with 6 of these, using 14-10 Zinger props...
Tried 15-8s, not enough rpm to get the thrust needed to get off the water..Flew it at about 1/2 throttle once in the air....

http://www.shindaiwa.com/products/br...ters/c230.html

I just looked up the older one, is a t230


Darin

Whats that going to weigh? Fully modified--as light as you can get it.

I'm doing a search in this forum for this engine:

http://www.walmart.com/catalog/produ...Specifications

I'm not having much luck locating a Shindaiwa engine locally.

Any comments on the featherlite leaf blower from Poulan? 18cc

Edit:
Just been searching and reading up on the featherlite 18cc engine. Doesn't look to good. It could be made to run decent, if you wanted to do a bunch of machine work to it. I don't. It's not going to work. Most guys say the 21 and 25cc engines are as light as the featherlite.

39 oz with muffler ready to go on the older ones or 41oz. with the newer ones the older ones put out a little more power and weighs less, had the older one on a h9 90 size funtana at 10 lbs it had slow unlimited verticle . This is on straight gas with the lightened flywheel and lightened muffler and the fat trimmed from motor. I could probably squeeze a couple more oz. that I can see. I checked again and I am not sure what the older one is I have a unconverted one at the hangar I will go see what the model # is. later today.
I think we can get you set up with a pair for under 5lbs. ready to go. will you have the clearance for a 16in. or 18in. prop what about magneto clearance.if you want to run magneto and dont have the clearance thats ok I can move it to the rear and will and 1.5 oz.



Darin

I can get those the same weight, they will be cheaper but have less power, but at 15 lbs with 2 I think you will have more than enough even at higher altitudes. but I hate the spring mufflers.

Darin

does anyone know the weight on these poulan pro 25 cchttp://www.lawnstation.com/Line_Trimmers/Poulan/LSPL25SST.html

Rcpilet..Converted G23s...Right at 2 lbs, +or- an ounce or two...

Here's my two cents worth!!! Try the weadeater 18 or 21 CC converted to Gas/Glow Hybrid these will start on "either direction" so you don't have to purchase especial props, just invert the prop side and the starting rotation on the rear engine, these engines converted to Gasd/Glow Hybrid should weigh less than 2 pounds and would be a great substitue for a 60 or 90 size plane; on this forum some mentioned thar they were selling these engines for $ 35.00 I will try to locate the info from back dates also there was some one on e-bay selling these little gems, another great deal to try is this one www.duropower.com they have a 26 cc engine that is a Zenoha replica from china for $49.00; But best of all if this is your "DREAM PLANE" I'll plainly tell you "DON'T SIT THERE GO FOR IT BUDDY" there is nothing like building your dream come true.