Hi, I've just accquired an Aviomodelli Cessna Skymater kit and was wondering what engines to use, I was thinking of a couple of Irvine .53's. Anyone flown one of these models and if so what engines did you use?? For the record, I fly off a pretty rough grass strip.

hi
a friend of mine has this model.
he puts a os91 at front and a 61 at the back as pusher.
this model is heavy and needs lots of power.
i would have put 2 os 91 4t front and rear - it will more realistic with a 4t motor than a 2t.

enjoy, you got a nice plane

gadix

We have a guy at our club who built one of these. He put an OS 46 up front and a 40 in the rear. Way underpowered. He lost one engine on the first flight, stalled it and augered in. What a mess. I think for 2 strokes two .61's would be fine but even better with 2 91 4 strokes.

meesh, thanks for that, I'm now thinking of using 2 Irvine 72's, any thoughts anyone??

I have the Aviomodelli Skymaster ....... ARF???....... myself. What a shock when I received it. I ordered the Cant Z tri-engine bomber as well. I think the Italians have a strange idea of 50% arf.[X(] No, it isn't finished yet
Anyway......
I wouldn't put anything less than 91 4 strokers. I fly my friends KMP sky master and the strokers are the correct power as far as I'm concerned. Especially if I were to fly from a rough grass field. You need the torque and reserve power for single engine operation and I've had to fly on one engine. I was even able to takeoff - marginally- with the rear engines prop on backward. Always double check that rear prop when you replace it for any reason. Even when you trust the person who did it!. The point is that the extra power is very important in an emergency. At our field we have horrible rain ditches just pass the end of our runway. A real killer if you can't get down fast enough after a engine failure on take off!

Hi
I am also building the Skymaster & plan to use a Saito 65 up front & 56 rear. During the build I have lightenened the structure where possible. Ply fuselage sheeting has been replaced with 1/8" balsa, the heavy aluminium u/c has been profiled & lightening holes drill in the centre section. Nest step is the booms & tailplane which again will be lightened where possible. A good source of info is www.flyingmodels.org which has a detailed build article on the Skymaster with a number of useful tips.

Thanks for the advice guys, I agree with the general consensus that it will need to be lightened considerably.

Wouldn't the power output of a .72 2 stroke be around the same as a .91 4 stroke?? It just that I already have 1 and would only need to buy 1 more, but if I went down the .91 4 stroke road I'll be looking to buy 2. I'm trying to keep the budget reasonable on this one.

Hope the advice helps out. Just don't weaken the stress areas where the booms and center section go together. You need it to be ridged.
As far as the budgetary constraints go I can completely understand! I usually compare horsepower, prop size and RPM. I would also send out feelers in RC universe for opinions comparing your engine choices. That way you can make a informed decision. I would think a .72 may have more power than a .91 4 stroke as the .91 is generally equivalent to a .60 2 stroke
Good luck[8D]

Dennis:

Depends on the two stroke 72 and the four stroke 92. An OS 92 4s will be about the same power as the average 2s 72, but heavier and more expensive. A net loss. Magnum 4s engines are equal to the OS in everything but the price, the Maggies are a lot less expensive. The Saito FA-90 will be more powerful and lighter than most 2s 72 engines, a net gain except for the cost. The YS 90 will blow them all away, and blow your wad when you buy them.

Finally, a good pair two stroke 72 engines should fly the plane fine.

Have fun.

But the four stroke engines would really sound a lot better.

Bill.

I was planning on using Irvine .72's, but I agree, the 4 stokes would sound a whole lot better but I also have to bear in mind cost. 2 x Irivne .72 2 strokes costs about the same as 1 x OS 91 4 stoke.

Dennis

Why don't you use the Magnum or ASP 91 4 stroke? You'll never wear them out.


Bob

What do you guys think about a couple RCS 1.40 gassers? 22cc gas engines would be CHEAP on fuel and the reliability of a gasser can't be beat.

I'm just worried about weight and wing loading.