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bob27s -> Sport Jett 50 in Patriot? (1/30/2003 11:53:57 PM)
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Hi,
Thank you for writing.
I personally fly a SJ-50 in my Patriot ARF. It is the perferct powerplant for that airplane.
Pleanty fast, very reliable.
The engine and muffler will work in a good power band up to about 18000 rpm. You can experiement with props that keep you in the 16,500 to 18,000 rpm range.
Always set the mixture on this engine slightly rich on the ground. Breifly find peak rpm (by ear, or tach) then back the needle out a serious 1/4 turn to drop about 500 rpm.
From my experience with the combination, my favorite prop is still the good ole APC 10x6. It provides wonderful all-around performance. I have experiement with APC 10x7, 10.5x6, 9x8, 9x7 and a few of the APC D1 serise Q-500 props. Of the racing props, the 8.8x9.0 and 8.8x9.25 work quite well. Initial take-off performance will suffer a bit, but they unload quite nicely in the air.
You will see props 9" dia or less mentioned for the SJ-50 in a lot of posts for the Whiplash and such. They work well there, but the Patriot is just a bigger plane, and will not achieve enough speed to let the little props unload and do their job well.
Hard to provide much more detail info, because I just leave the 10x6 on the Patriot most of the time and enjoy the plane :cool:
An 11x7 is too much prop (per other post) for the SJ-50. The engine will not unload as well in the air. An 11x5 or 11x6 would be better choice, and will actually give you excellent take-off and landing performance, but lower top end flight speed. Ground clearance is an issue for me, so I have not attempted this with the sj50
An APC 10x8 might be ok, as long as it will peak near 16,500 on the ground, and you can launch it at about 16,000. Engine will unload quite a bit in the air. Only try this after proper engine break-in, and then about 30 min of flight time.
I hope this is helpful
Bob Brassell
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