I have a line on a Eager Beaver III-SX string trimmer. It's has a 21.2 cc McCulloch engine, which I'd like to put on my Vectorflight Extra 300s, the one with the 66 inch wingspan. I believe it will be about an 8 pound plane when assembled. While the firewall is big enough for this engine, the plane instructions call for a .60 - .90 2 stroke engine. The 21.2 is around 1.25 cu. in., which sounds like fun.

A few questions:

1. Is this a decent engine for conversion?

2. It has Walbro carb, which I suspect is a good thing, yes?

3. Your thoughts on this size for a sports/aerobatic plane which calls for a .60 - .90 2 stroke.

This would be my first conversion, but I'm mechanically inclined and do my own automotive work, including a full rebuild, so I have decent skills and tools. The engine pulls smoothly, but does not currently start. It also has 5 year old gas in it.

Thanks in advance for your help and suggestions.

Jack


I found the engine size here http://books.google.com/books?id=VFV...sult#PPA146,M1

Things to take into consideration in my opinion are.....

1: Does it have good compression?
2: Is the carb and muffler on the rear or the side of the engine? (side is better)
3: Is it a long shaft or short shaft? (long is usually better,but its hard to tell till you rip it apart)
4: Do you plan on buying an electronic ignition for it? (I recommend it for a small engine like this)
5: Custom hubs and mufflers are hard for some people to get made or to make themselves,so can you get these made?

Long shaft engines make it ALOT easier to make hubs for,and whether or not your carb and/or muffler is on the side or rear of the engine usually dictates whether or not you'll need "stand-offs". I've found every engine is different,but theres usually a way to make it work if your handy enough or have access to a good metal shop.

Dont spend any of time converting that engine to put on that plane in my opinion.It wont put out enough power.I had 2 of them.They are on the heavy side.Youd be much better off with an echo 24cc,a stihl 25.4cc,a stihl 28cc.These are lighter engines and have more power.The stihl 28 is on the larger size but without knowing your wing area i cant say for sure.
A good echo 21cc might work if ya run it on gas/glow mix.I have a couple 22cc stihls that would work.
What size is your wing area.

Buck1856,

Thanks for the quick and straight forward response. The plane's specs are as follows:

Wingspan: 66.00 inches
Wing Loading: 26.5 oz./sq.in.
Length: 55.00 inches
Weight: 8.25 Lbs.
Airfoil: Fully Symmetrical

Oops, that does not give you wing area. I hope the loading is sufficient information. If not, I'll go digging.

Jack

If its suppose to fly with a .60-.90 engine and it will have a wing loading of 26 oz sgft,with a gas engine on it youll be in the 30-35 oz sg ft.Thats warbird territory there.Youll be coming in hot for a landing and youll not be doing any 3D or very good aerobatics.I had my echo 24cc on a 1/4 scale Giles 202.The one from great planes,the arf.73 inch WS and more wing area and better loading than your plane and after 3 flights i took the engine off and sold the plane.My plane weighed 10.25 lbs.
I would either pick up a little larger plane,like an ARF from Nitro-planes.Av8tor that hangs out here in these forums bought the giles and put a 25cc homlite on it.Look up that thread.He might jump in here also.He has quite a few planes on gas/glow,mostly echos.
Im only being straight forward because i know you wont be satisfied like i was with a small plane.If you must use a small plane then look at jezmos thread[s] and see what he did with his glow conversions.I right now am converting a ST- G-2000 to gas or gas/glow.It was given to me with a bent crank.I straightnened it,and then i made an adaptor for a walbro carb so far.I have to get a new ring[dont ask] and then ill put it backtogether.Then ill post a pic.
What kind of plane are you looking to fly,what style of flying?We can help with a plane and engine combo with that info probably.

Buck1856,

While I'm not thrilled with what I am hearing, I am glad to hear it before I experienced it.

I appreciate your help and will wait to go with a bigger plane, but I'll keep my eyes open for the engines you suggested as potential candidates. I started looking gassers now to fit this plane. I'll be looking at other engines for this plane and will worry about a bigger plane when I have time and money for another bird.

Thank you,

Jack

I am not trying to steer you away from conversions ,just for this plane.I have quite a few conversions running and even more to do.Spend a little time in these forums and look at what where converting and what there going on.Plus keep your eyes open for the engines i mentioned.If you would like some more help with specifics send me a P.M.This way we can discuss this farther without being moderated.I have a few extra engines laying around and i have a supplier of some.I quess i did somthing wrong in my last post,thats why some of it is crossed out.Ill have to go edit it a little and see what i did.
Ill go look for a thread here in the conversions,you might look also.There was a guy who i believe put an 18cc on a frenzy or somthing like that but i dont remember the wingspan or anything,ill see if i can find it.He said it flew pretty good.

I usually recommend an airplane of around 1000 square inches of wing area and 10 lbs. as a minimum airplane for gasoline engine use. If you put a heavier gas engine on a smallish plane, you are going to have a heavy, marginal flier on your hands and that's no fun. Check out some of the 72" and up wingspan models offered by Nitroplanes. They have a nice looking model called the CMP Marathon that is designed for 20 to 24cc gas engines. Nitroplanes prices just can't be beat, and I have been happy with a number of their planes. I presently have three of their designs flying gas engines.

http://www.nitroplanes.com/ma20aeairera.html

Good luck,
AV8TOR

Thanks for that link...there is more data there, all in one place than a person can imanage! I noticed the 13.8cc,16cc and the 21.2cc Echo all have the same stroke of 26mm. There is more data for other brands too! Good going! Capt,n

Also they are talking about a 65 inch span Airplane here. Capt,n http://www.rcuniverse.com/forum/m_8117173/tm.htm

Buck1856 – You are not deterring me from a conversion, only making me aware that the plane I’m considering is too small. This is why I asked the question. I’ve been reading the forum for a few weeks and will continue to do so, but this engine became available, so I had to ask.

The Frenzy is a bit larger craft than my 300S. If he was happy with an 18 in that plane, I probably won’t be with a 21.2cc in mine, expecially since the 21.2cc does not have a good power to weight ratio.

av8tor1977 – That is good baseline info. Thanks! Unfortunately, right now I am trying to find an engine for a plane, not a plane for an engine. <grin> I’m always looking for new planes, and I guess now I’ll be looking for engines too.

Captinjohn – That’s why I provided the link too. Being a newbie on this forum, I didn’t know if that site was a commonly known one or not, so I supplied the source. I’m glad to have been able to contribute, even a tiny bit, ‘cause I’ll be taking a lot more information out, than putting in, over the next few months.

Thanks everyone. I appreciate the help. I’ll keep reading, while I look for a good engine and a bigger plane.

Jack

Hey I just dug one of these out of my engine pile :-) Eager beaver I-SX
If you do a search for " Featherlite " here in the conversion forum you'll find many 18cc and 21cc ideas.

I'm building a 106" span floater Pawnee clone, 1920sq-in and just a big putt-putt AP ship. They have a long nose so the little 21 on EI will do the trick.
Good luck with yours!