flyrotary@lancaironline.net Mailing List Archive

Message

Correct on all counts Rusty. I'm using the airplane as a dyno in these tests which has very little to do with the way airplanes are actually used. As I have said in the past, top speed and HP numbers are good for only one thing - Hangar bragging rights. My comment about never testing above 6000 applies only to the recent Renesis testing.

As an example of why it makes no sense to go fast down low, I can fly 202 mph at 1000 ft (not full throttle) while sweating profusely in a hot cockpit while burning about 16 GPH. I can go the same speed at 14000 ft in complete comfort while burning 8.25 GPH (numbers from earlier 2nd gen 13B engine).

Tracy (installing longer intake runners in shoebox manifold - Turbo flyers beware : )

----- Original Message -----

From: Russell Duffy

To: Rotary motors in aircraft

Sent: Wednesday, November 10, 2004 8:56 AM

Subject: [FlyRotary] Re: best cruise altitude and power, turbo folks may delete- was Re: EWP Info- Lynn?

The 7300 rpm test was at 1500 ft. IAS was bouncing (rough air) around 224 and the EM2 TAS was showing 235 but I have not calibrated the TAS function yet. Its probably on the optimistic side. Or maybe oil on the belly makes me go faster : )

From memory, I have not had the Renesis over 6000 ft nor have I even attempted to measure maximum speed above 2000 ft.

Tracy (making longer intake runners for the shoebox manifold)

Thanks for the info Tracy. Oddly, I've only done top speed tests above 5000 feet recently, so I don't have anything to directly compare.

I'm wondering what the "normal" best cruise speed altitude will be for us. With a certified relic (engine), you're only allowed to run 75% power continuously, so the best cruise speed is the highest altitude where you can still make 75% power. As I understand it, that's about 8000 feet. Van has always been irritated by people giving speed figures for RV's without following the "standard" practice of measuring it at 8000 feet. In our case though, we're not limited by the 75% power rule.

It's hard to let go of the 8000 foot rule of thumb, but I guess it really doesn't apply. I'm sure there's a level of HP that would be considered a safe max for extended operation, but I have no idea what that is. Has anyone designated a max HP level for continuous operation?

Rusty (haven't got anything done on my oil scoop or TB inlet)