Sport_Pilot

Yes but the FP is an older engine, as well as the LA 40.

ronwc

My Feedback: (404)

I have built, flown and owned many twin's over the last 50 years or so. Both the FP and LA are good dependable engines, and are surprisingly strong - although as mentioned earlier, they take many runs to break in, and you need to keep them on the rich side. The main thing you want with twins is reliability. Ball bearing twin needle carb engines are somewhat stronger, but most guys way overpower thier twins anyway. I have read and believe to be true, that two engines equal more power than if you doubled the two into one - in other words, a twin engine 25 would be equal to more than one 50 size engine.

One piece of advice i would give to anyone flying a twin would be - tune one engine slightly rich with a good reliable idle, shut off - tune the other engine the same way, shut off - refuel both, start and fly. Don't worry about exact sync, and don't try to retune one with both engines running. Guys get in trouble when they get both running good, run them up before takeoff, and try to sync by leaning one engine down - that's the one that cuts off on takeoff or when flying.

Here are a few of my twins i am flying now. The one wth 3 engines are OS 28 FSR's (20 + years old). The Twinstar is running two OS 25 LA's.

rgburrill

Blue heads are pretty

NoOneFlysAtMyClub

My Feedback: (32)

Thanks!!!

jpbugdust

Got a brand new O.S. Max .10 LA from e-bay for $41 dollars. (Had to pay $8 for shipping and handling. Ouch !) Am just getting back into internal-combustion motors. Have been flying electrics the last twenty years. My favorite motor many years ago was the old style Max .10. It was stone reliable. The new Max .10 is completely different. It has schnuerle-porting which is very different from the old models. What surprises me though is the quality of construction. This little motor is absolutely exquisite ! It is a real gem ! The quality control on the O.S. Max machine shop and assembly line must be very strict. I broke this motor in with Byron Genera-2 fuel. (20% oil and 15% nitro-methane.) Ran it on the rich side to break it in. Am using a 7" by 3" E prop. (Bought the prop from "voconio" on e-bay.) I'm gonna have to "eye-ball engineer" a model plane to hang this engine on so I can fly it.

jeffie8696

I have flown my OS10FP in an AKModels Extra with good results. Very reliable little engine. I have 2 now and hope to build a twin some day.

1QwkSport2.5r

Although I am not an OS fan, I did acquire one (an FP .10) at an estate sale early this spring for a couple dollars NIB. The casting is nice, the engine appears well made. The engine ran on the bench fine, started easily and the airbleed carburetor functions O.K. though it could be better. My engine (ABN) was made around 1987 or so and had the loosest piston/liner fit I've ever dealt with. I run it on 5% nitro 25% castor as I do in all of my bushed and lapped engines. Lowest idle speed I got on a 6x3 was 3300 or so, closer to 3000rpm on a 7x4. When the liner peels, if it does, I'll chuck it and get an Enya. If someone offered to trade me an Enya .09-.11 for my FP, I'd consider it. For now its in a Norvel Neofun classic 1/2a trainer. I could see bare brass in the exhaust port in the liner which made me think it was actually ABC and not ABN, but after removing the liner and looking at it closer it is in fact ABN but with a poorly plated liner. Nickel liners are completely plated whereas most of the chromed liners are only plated in the bore.

Nonetheless, enough people say these FP's run well and last a long time, I'll take it for what it is. I'll fly it until it nose dives into the dirt or it wears out or someone trades me for it.

aspeed

I think the OP has moved on, but I tached an FP with no muffler, 10% and the thinner 7-4 MA prop at 17,400 rpm and the LA .10 at 17,500 same conditions. After taking off the head to see what length of plug to use, I noticed the head clearance was real big, so I made up a thinner washer at .005" instead of the .015" or whatever it was. It then tached 18,000. I flew a kind of heavy (standard size servos) Misflit for many years with the FP .10 having used the TTiger .10 (that only would run 13,500(with muffler though) It would barely get the plane off the ground with the TT. Oh and the LA .10 and .15 are not really schneurle ported, as they are missing the boost port. But still seem to put out the power anyway. I also noticed today that the FP .15 has 6 bolts holding the head on instead of 4 on the LA. .15, so I think the LA with the plastic backplate which breaks the needles easily, is made cheaper, lighter, and more powerful maybe slightly.

1QwkSport2.5r

I know its an old thread, but someone else revisited it and I figured I'd chime in. Anyway, I haven't measured the compression ratio or head shims yet, pretty much just got a little runtime on it to get a feel for it and that was about it. I didnt record any tach numbers or try too many different props. I was going to at some point make some timing changes and change the CR a little to see if it will give up any more power.. But this wont be for awhile. Hoping to get it as-is in the air next summer and maybe fly it myself...

NoOneFlysAtMyClub

My Feedback: (32)

Hi all,

I had forgotten about my original post. Just saw this and thought I would update.

I ended up using 6 MDS .18's. They are ball bearing engines with two needle carbs. These engines run fantastic. 7X4 APC props, 5% nitro fuel. The best part
is I only paid $ 30.00 apiece for them. Five were new, one bench run only. Best transitioning engines I own. I have not flown it yet. New job, new house in new city, thanks recession.
Plane is a Big Apple by Dick Sarpolis modded to look like a bomber. Built from plans with my mods. Longer wing, larger stab and fin. Had to use fixed gear, wing is not thick enough for my dual wheel mains.
I sanded some covering to dull it, placed it here and there to simulate panels but it did not turn out very good. Looks like patches. But, as they say, you will not see them in the air.
Here are a few photos.

Thanks, Tony

1QwkSport2.5r

Nice work! That thing has got to sound awesome when all 6 are running.

NoOneFlysAtMyClub

My Feedback: (32)

It does have a very unique sound. One nobody at the club has ever heard.