Which IPS

[Don Cooper]

Dave,
In your post about your OTW biplane you mentioned you were using the IPS 'E'. I have been playing with a series of semi-aerobatic IPS powered planes with the following general characteristics: rectangular wing with spans from 26" to 28" and chord (including full span aileron) from 7.5" to 8.5", mid wing, current version uses the Clark Y, open cockpit, weight (everything but battery) from 4 to 4.5 oz. They have all been considerably faster than the GWS Cub, Tiger Moth, etc., so I have been using the lower end of the IPS range ('A', S1, S2). Should I be looking at the upper end? I realize the surest way is 'try it and see', but any comments/advice would be appreciated.

[Dave Robelen]

Hi Don,
The hitch with going to the high ratios for a faster flying model is the lower prop RPM. This generally means a large dia blade with high pitch. The 11-8 Works fine on the Meyers, but it is not a speedy model, and I was looking for some extra thrust to compensate for the biplane drag. It worked just fine.
When I was looking for some extra poop for my small aerobats, I stuck a GWS EDF motor in the E gearbox, and ran it on 8 ni-cds. Spinning a 9-6 APC, this setup draws 2.4A static, and shows a 40% thrust gain over the low ratio series and the same prop., at all speeds up to 25 mph. That might work pretty well in your case.
Regards, Dave

[Don Cooper]

Dave.
Thanks for the info. I will give it a try.

Don