I am breaking in my Enya .61 CXRS PRO with an 11x5.5 and a 12x4.
Is a 13x5 or 13x4 too much for this engine for a good stunt run. It is going on my ARF Strega.
Thankee in advance for any intel.
Shug

Shug, I've got both the ABC and ringed 61CXL, with rear exhaust, and will be using the header muffler rather than a pipe. I'm intending to use a 13x5 as a starting point, once I get around to building something suitable. I've also got an Eather 3B 12x6 that I could try, just to see what happens (too much pitch?). Like you, though, I'd be keen to hear from someone with practical experience of what works well.

Also, can anyone give me an idea of roughly how much fuel these things use for a pattern?

The APC 13x4 is not too much prop for the Enya. I have used this prop with my Strega/Enya 61CX, then later I changed to a 13x4.5 3B Bolly to get the performance I needed to compete with the other guys using PAs and Rojetts.

This engine has some serious metallurgy and even after you break in on the bench, it will still be tight. It will run stronger and stronger as you use it. I assure you it has the muscle to carry the big and heavy Strega.

The engine will work with 13x6, 13x5, 13x4 props. However, the best performance you will get with a low pitch prop launching at 10500rpms and with lines as long as possible so it is legal. My Strega ARC was heavy and I used long lines to allow the plane to fly fast so I could manage a descent corner.

Martin



p.s. a lot of info here :
http://stunthanger.com/smf/open-forum/strega-arf-overview-video)))))

This was 6 years ago and I got them from Randy Smith.

With many going to electric you may find someone selling some of these props. I believe there is some people making 3B C.F. Props in the US, ask around. Osni here in Brazil made some good props, not sure if he still making them, but I can ask if you need some.

Be aware when flying in still air. The Strega has a big wing, is heavy and with the Enya 61 spinning a 13" 3B Prop at 10500rpms it will make a lot of wake turbulence, so make sure to walk back a lot more then normal to avoid passing through this wake turbulence.

Back then I was a Hookie and when I show up at the circle with a low pitch 3B C.F prop for a muffled 61 engine the experts said I should not even try that because there is no way a prop for a tune pipe 65/75 would work in a sport muffled 61 engine, even worst, with a .45 size conrod! In the first try it really did not work and they made jokes cause I did not listen . These "experts" told me I HAD to use 12x5.5 3b. Well I don't give up on the first try. The  Bolly had 4.5 pitch and I knew the Engine would develop more Torque in higher rpm. So I replaced the stock 7.5mm venturi with a 8.5mm one and re-pitch the prop to 4"  and the "magic" happened! It ran very strong and power the Strega with tremendous authority. The not famous and sport engine turn out to be a little Monster and it help me advance in the game.

I got that engine used, actually I was the 3rd owner, so the engine was fully broken in. The previous owners followed the advice of the so called "experts" and they never got good results with it trying to make it run like an ST60, so they pass on the engine. Later I tried a new 61CX engine that I broke in with 6 full tanks and by far it did not run as strong. I started to believe one of the previous owner had modified that 61CX, so I took the engines a part to check, did not find any differences. The reason the old one ran stronger was because it had lots of used time and was totally loose. Perhaps if I had started with a new engine I would also give up on the Strega.

The point is, this engine will get stronger and stronger as you use it. Don't give up if it does not run very strong in the beginning.

If you stick a big prop and the engine still tight you may force the conrod and create an undesirable gap in the conrod. So my advice is to do a good break in with the 11" prop and then use the APC 13x4 2B for flying, then later try the 13x3.75 3B prop, just to make sure.

The APC 13x4 works well but in windy conditions it will wind up. When you get a 3B C.F prop, please let me know and I will tell you how to set up the pitch on the blades so you can fly in strong winds at the contests. I used 2 props, one for normal day and one for windy days. Yes! there is a lot of details to take care of to be competitive and get good results with the Strega/Enya 61CX.

If it was a smaller and lighter model it would be less complicated,  but to fly a big plane like this you need to get all the performance the Engine can produce, and these tips I am giving you makes all the difference.

Martin