SIG AKROMASTER --- OS 15 FP or OS III 15 ??

Hi, I'm building my new plane. SIG Akromaster. What's better, the OS MAX 15 FP or the OS 15 III ??
I'll fly using 0,15 x 52 lines.
Thanks!!

Depends on what you want the plane to do. My personal choice would be the FP. I like power.

The .15 FP is pretty heavy for a model this small. I flew mine on a Tee Dee .09 and then later with an O.S. .10 FP. Even the .10 made it nose heavy. This model isn't much larger than a 1/2A stunter. My next one will have a Norvel .061.
Chris

I think the FP is way too much for the Akromaster. If I had your choice, I would use the Max MkIII but I am building one at presesnt for an FP10.

Good luck with it, Geoff

I don't see how the FP-15 can be too much engine for an Akromaster. Mine has an FP-25 and it motors around as easy as you please with a 9/6 nylon prop.

(Can't tell you the name of the prop manufacturer. It's a little worn.)

Randi

>I don't see how the FP-15 can be too much engine for an
>Akromaster. Mine has an FP-25 and it motors around as easy as
>you please with a 9/6 nylon prop.
>
>(Can't tell you the name of the prop manufacturer. It's a
>little worn.)
>
>Randi

Hi Randi, my issue with big engines in little airplanes, is not that
the model is overpowered; but that the wing loading climbs too high.
As you've pointed out, the engine can be slowed to appropriate airspeeds.
This little Akromaster only has 250sq"s and doesn't fly that well when it
gains weight. I mention in a prior post that I have two Akromasters.
One is powered by a .15 diesel(engine wgt.five ozs) the entire
model weighs 17.5ozs ready to fly. It flys like a mini elephant.
My other Akromaster weighs 12.5ozs powered by an MP-Jet .061 diesel(3 ozs).
It flys fast,turns very tight and is a joy to fly. the 1.0cc model
flys on 45' lines and the .15d model flys on 60' lines.
What does your Akromaster weigh?
Tony G

I got lots of static last year for putting an Enya 19-3 on mine. If you move the engine back some, it will help a lot with the balance thing. I'm going to build another one but this time I'll use the leading and trailing edges full length and not cut them down. Have to make a few extra ribs but it extends the wingspan quite a lot. Mine flys well, but my new Flite Streak with a Fox 35 is way better. I'm hoping that a bigger wing will improve my next Akromaster and make it more like my Streak. Good luck.

>Hi, I'm building my new plane. SIG Akromaster. What's better,
>the OS MAX 15 FP or the OS 15 III ??
>I'll fly using 0,15 x 52 lines.
>Thanks!!
This is a plane that was designed around the Fox 15. At 3.5 oz it will balance well. The others are way too heavy for it including the OS10. My choices are the TD 09, pretty powerful, and the Norvel 074 also pretty good power. The downside is they are out of production, have integral glow plugs, hard or impossible to find, like Cox Grey 7/3.5 props. also impossible to find. Other then that though they are really a perfect match for the plane.
On the other hand since you mentioned these 2 motors we have to assume that those are the 2 choices that you have. Use the FP at least you can get parts for it. The os Max 3 is getting long in the tooth and parts are getting tough to find also.
Dennis

Use the 15 III and get you some .012 lines. You will be happy!

The FP15 will probably make the Akromaster a rocket. Slow combat speeds. Actually, I'm thinking of doing one like that. The wing of an Akro has been hanging from the wall of my shop for two years. Just took the last bit of twist out of the trailling edge. If you use an FP15 the model will not to be confused with a stunt trainer. On the other hand a club member and his ten year old son fly an Akro with an Enya 15iii. A fairly mild engine, similar to the older Max 15iii, you've got. It'll do the round pattern maneuvers o.k. Lots of fun. I bought an Fp10 to power this sized aircraft. My thought was, it would work on a jr Streak, slowing it down enough to do lots of the pattern. With an FP15 the jr Streaks are rockets, will keep you laughing if you can keep up, but not an easy plane to fly. Find someone to make a light tongue muffler. As folks have noted, these engines put a lot of weight in the nose. Definitely use .012s.

>The FP15 will probably make the Akromaster a rocket. Slow
>combat speeds. Actually, I'm thinking of doing one like that.
>The wing of an Akro has been hanging from the wall of my shop
>for two years. Just took the last bit of twist out of the
>trailling edge. If you use an FP15 the model will not to be
>confused with a stunt trainer. On the other hand a club member
>and his ten year old son fly an Akro with an Enya 15iii. A
>fairly mild engine, similar to the older Max 15iii, you've
>got. It'll do the round pattern maneuvers o.k. Lots of fun. I
>bought an Fp10 to power this sized aircraft. My thought was,
>it would work on a jr Streak, slowing it down enough to do
>lots of the pattern. With an FP15 the jr Streaks are rockets,
>will keep you laughing if you can keep up, but not an easy
>plane to fly. Find someone to make a light tongue muffler. As
>folks have noted, these engines put a lot of weight in the
>nose. Definitely use .012s.

Dennis,
If you use an OS10 a one ounce tank will keep you up quite awhile, you might be suprised. I used a 7/4 on a Ring jr with that set up. It's as fast as a Fox 15X and cheap on fuel. Didn't go to an 8in prop as I think they are a bit much for the motor.
dennis

I like the FP's myself.My son is using an Enya.15 currently with 7x6 Tornado black prop with great results.I had to switch to tongue muffler to get plane to balance.I used light foamies for wheels and 1/2 ounce in the tail.I think this Enya makes as much power as the FP.My Akromaster is using a red head Mccoy .19.with a 8x4.I'm quite surprised thinking this would way overpower the plane but they're quite equal.The Enya is on uniflow with muffler pressure which gives it an awesome run consistantly.The Mccoy is standard vent with one vent capped.The Mccoy has its moments sometimes but is a good runner nonetheless. I fly both using 52 foot lines eye to eye.One of the fellows at our club was using an FP .15 on his jr Flite Streak which was quite impressive.We timed his laps to our Enya.At the time I wasn't on uniflow and he had me.I think I'll give him a run for his money now. Ken

Ken we're talking about each other! Guess you fixed your computer.

Dennis Moritz

I think a Profi 15 or a Fora 15 would be just the thing for a sig akromaster.

Well for a Jr. Flite Streak anyway. Will have to talk to Phil Cartier. The conversation is long overdue. I'm thinking of cutting the nose back some on my next jr streak, build a box in the wing and run a bladder. Didn't think of a Profi. Good idea. Phil has been getting 21,000 plus out of la15s. Told it's reliable stunt run I imagine a Profi from Phil would wind some ridiculous revs. The 2 minute or less pattern. Why isn't that an AMA sanctioned event.

I had an Akromaster with a .15 III on it, and it was way nose-heavy. Note that this plane is about 250 sq. in., that's not much bigger than most 1/2-A Combat planes these days. Built light, you could probably fly it with a Norvel .061.

>I had an Akromaster with a .15 III on it, and it was way
>nose-heavy. Note that this plane is about 250 sq. in., that's
>not much bigger than most 1/2-A Combat planes these days.
>Built light, you could probably fly it with a Norvel .061.
>
>
Isky.absolutely right on. I've got an MP-Jet .061 diesel in mine.
I'll bet it flys better than most other Akromaster/ .15 combos. I know
how badly my 17.5oz Silver Swallow .15D powered Akromaster flys...just too much
wing loading for the model. The MP-Jet version weighs 12.5ozs.

Tony

>Well for a Jr. Flite Streak anyway. Will have to talk to Phil
>Cartier. The conversation is long overdue. I'm thinking of
>cutting the nose back some on my next jr streak, build a box
>in the wing and run a bladder. Didn't think of a Profi. Good
>idea. Phil has been getting 21,000 plus out of la15s. Told
>it's reliable stunt run I imagine a Profi from Phil would
>wind some ridiculous revs. The 2 minute or less pattern. Why
>isn't that an AMA sanctioned event.

Larry Scarinzi was flying a Scared Kitten with some sort of F2D engine some years back. The noisiest thing on the Stunt Circles!

Dennis I didn't see your post until I posted mine.The computer is working great compliments of a new hard drive.As for the Akromaster,Shawn wouldn't trade it for the world.That plane has been a terrific plane for him.I always had a few in the box so it was a great step for him coming from a jr Ringmaster.I myself have an OS 111.I indeed want to use it.I believe it shares the same bolt pattern as my Cox medallion 15.I have a great little Midwest Me-109 I want to use the OS on.It seems to be the most friendly of all my .15's.Has anyone have the actual weight differences between the Os 111 and the FP?I'm strictly guessing here but the 111 might be the heavier.I really had to do some tinkering to get mine to balance right.I took the tail feathers clean off on landing the first flight due to flipping over. ken

My vote would be for the FP 15. I moved my La 15 as far back in the
mounts I could. I am not nose heavy but my plane isn't exactly light at
19 oz. I have only 3 flights but I had no problem with figure 8's
outside loops and wingovers. It was a lot of fun after not flying for
30 years. I did save about 1/3 oz by removing the baffle and grinding
off the cooling fins from the muffler.

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