hogflyer

I just ran in and flew my Evo .61 today after removing the limiting pin and the collar on the idle mixture, and the pin on the high end, but not the collar. I decided to use the stock 3-blade prop and flywheel that comes with the Alpha 60 RTF as I wanted to see how the plane would perform stock. It started on the first touch of the starter and went right into a nice idle but wouldn't accelerate. Found it was too rich, and just a tweak of the mixture leaned it enough to get up to full throttle. I ran it in alternating with a 4-stroke rich for a couple of minutes to peaking it out for 30- 45 seconds, running a full thank of fuel through. Second run it started on the first flip, I peaked it then backed off a few hundred RPM and set the idle mixture. It transitions nicely, but a bit sluggishly which I attribute to the flywheel.

I did notice a bit of gray initially in the exhaust, but it quickly disappeared, but I couldn't feel any grit. After a couple of minutes it was normal. I measured the prop and it's a 13" dia (don't know the pitch) 3-blade - I was able to get only 9500 RPM out of it, but idle was around 2100 RPM. I plan on changing the 3-blade out for a 2-blade 13 X 5 - the Alpha will be used to giving flight instruction so it doesn't need to be pitched for speed - I'd rather have a slower plane with a better climb.

So - a couple of questions on this engine and prop.....

What is the actual diameter/pitch of the Alpha 60 3-blade prop?

Is 9500 RPM OK for the 3-blade prop, or should it be higher?

Hogflyer

blw

My Feedback: (3)

I only know the diameter of the prop for the .455 TPS engine, and that one is 9". It is pretty much a dog for a prop, and one blade was significantly out of balance with the other two. The only advantage that I saw was it was good for braking action when on approach to land. Well, it was good for ground clearance too.

The .61 is a pretty good engine. These engines idle fine and the flywheel weight just bogs it down. The engine will wake up a lot when you remove it, and take out the OS 8 plug. Try both the Saito SS and OS A3 plugs. The A3 is hotter, and may well be the best plug for your engine. The plane will need to be rebalanced when you remove that heavy counterweight.

I suggest that you replace the 3 bladed prop.

The sluggishness is a combination of the counterweight, OS 8 plug (if that is what is in there), and the 3 bladed prop.

AKFireMedic

My Feedback: (2)

I have the evo .61 in my alph as well. It runs very well now and has enough grunt to hover the plane as long as I can keep it straight. I'm running with all the factory needle limiters removed, the baffle from the exaust removed, flywheel eliminated, and an APC 13x4 prop with a plastic spinner on Omega 15%.