Covered in part in my earlier post about prop size but what do you all suggest would be a reasonable engine for a Western Magnum? There's no way my son can afford the proper West+Genesis pipe, he got the bare, built plane off Ebay but without the engine. So far we have managed to figure that the OS40 FP Max isn't going to do a lot in it so what's the suggestions? I'm thinking maybe an Irvine 46?
He wants a bit of speed but not the breakneck 200mph quoted as it's capability!!
TIA
cheers, Len
"> managed to figure that the OS40 FP Max isn't going to do a lot in it
See my previous Always can contact Weston. You will need a pipe at some stage to get maximum power.
# I think a cooking 40 will work. but you ne to get the revs and the prop pitch up a bit - so 9x9 sort of prop is called for. Maybe even 8".
try some blues :-)
By a cooking 40 I'm assuming the OS FP doesn't fit this description? It certainly doesn't want to scream but I didn't try a smaller prop! I was running it on an 11x6. Maybe I'll buy a 9x9 and see what it goes like?
cheers, Len
It still won't go. That engine only puts out 1hp at 17k. The only way it'll rev that fast is without a prop!
If you want good speed, try one of the modern .46-.50 ball bearing engines such as a Supertigre .45, GMS .47 or MVVS. For a little more money, you can also do well with a Webra .50. Use a Mousse Can Pipe (Muffler if you must) and you will get between 500-1500 more RPMs. All of those engines I mentioned should be able tot urn an APC 10X6 over 14K on the ground with 10% sport fuel.
Contradiction in terms. Without a prop it will develop no torque, and therefore no power at all.
If it does its bhp at 17k, find a prop that will let it do that. I'd say its woryh a try on something around teh 8-9" mark anyway, since you have it.
But for real speed, you still want something with more pitch and probably less diameter.
Wow, you got no sense of humor at all! The FP isn't ever going to get to
17K with any kind of useable prop.Also, the RPM figure for the engines with the 10X6 was for demonsrtation purposes. Giving RPMS for a prop everyone is familiar with gives them a reference point for other engines.
The review of the Evolution .46 I read indicated it was very happy spinning smaller props in the 17k range and had good power output up there. Might be a good affordable candidate. I think you might get up to the 140-150 regime with it? The Whiplash delta for example, a similar speed range type airplane, apparently tops out at about 150 with a .46 FX.
I have two Magnums - one is a spare airframe just in case. Have not flown it yet. It's a practice airplane for my Whiplash delta/Jett .50. Decided to "do fast" this year. Wife hasn't spotted the credit card bill, yet.
Mike D.
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