Bill, I'll see 7000 - 7200 rpm on initial takeoff roll. It settles in around 6800 and I keep it there until around 500' agl, then dial it back using prop to control engine rpm. I'm reluctant to push it due to gearbox limitations. Also, my intake is optimized for lower rpm range.
If I mess up and set the prop incorrectly for takeoff, I'll quickly bump up against the rev limiter. So, I know it will do it, just prefer to maximize longevity of the hardware by running it more conservatively.
Mark
Sent from my iPad
Nasty! Nasty! Nasty! :>)
I haven’t heard from Bobby in a
while. He was considering swapping that SC for a turbo. Made his
mind up yet?
How does that speed compare with your ES
cousins? That fuel flow indicates about 200 hp. Have you tried it
at a higher rpm? You could probably generate 300 hp or so with that PP
20B at 7000 or so. That would give you a 27-28 gpm fuel flow and probably
220-225 speed? That should run like an ES with an IO550 engine.
I left Sanford, Fl a while back with my son in his
Turbo Saratoga following me in a flight of two. He came over the radio
saying “Slow Down! I am burning 30 gpm back here and you are still
pulling away from me!” . :>) Best thing I had heard in
a long time! :>)
I set my prop for a 7000 rpm take off, showing
about 17-18 gpm, what do you use? I wouldn’t take my fuel flow to
the bank as I am not certain of the calibration yet.
Bill
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net]
Sent: Wednesday, August 06, 2014
6:19 PM
To: Rotary
motors in aircraft
Subject: [FlyRotary] Re: Trip
report
I stated my gear ratio is 2.17:1 in error. I'm actually running
the RD-2C which is the 2.85:1 gear set. Typically, I run wot too,
controlling engine rpm with prop pitch. The exception is when flying
formation with a certain Renesis-powered RV-10. Then I have to throttle
way back. I have lower gph, but use more fuel because it takes twice as
long to get to the destination.
I did one speed run recently and saw 221mph at 6k rpm, 18.5 gph.
Not something I'm willing to do for any length of time, but sure was fun
while it lasted.
Mark,
I suppose that your prop speed limits your
engine rpm to about 6100 max? At 8000-10000 ft, can you go WOT
without over speeding your prop? If you can and have, what TAS and fuel
burn do you get?
When I moved my plane from Florida to Texas,
I could only get to about 2000-3000 ft due to ceiling and headwinds. I
have the Renesis with the 2.85 PSRU and the MT electric 3 blade c/s prop.
I was getting 161-163 knots(185-188 mph) TAS with WOT, 6000 rpm, burning 9-10
gpm. I had the engine leaned to an A/F ratio of 16 using the wide band O2
sensor. I almost always fly WOT in order to reduce pumping losses in the
engine and I use the prop to control the engine rpm and therefore power.
The only time I use the throttle to control the engine power is as I approach
the airport for landing.
Any others with performance numbers on
their flying airplane?
Ed, we haven’t heard from you in a
while, how are you doing?
Bill
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
Sent: Wednesday, August 06, 2014
3:58 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Trip
report
Thanks for posting your numbers. I typically fly below 10,000, but at
the same rpm, higher MAP. Typical cruise is 195-200 mph, burning around
11.2-11.5 gph. Maybe I should slow down, or fly higher.
For those unfamiliar with my setup, it is a Lancair ES, 20B-PP, 2.17:1
psru, M/T electric 3-blade c/s prop.
On Wed, Aug 6, 2014 at 1:38 PM, Tracy
<flyrotary@lancaironline.net>
wrote:
Here's some trip data from a flight from Florida to Colorado
in the 20B powered RV-8. It's the first long trip where I was able to fly at or
near the altitudes it was optimized for. It didn't do as well as I had hoped in
terms of fuel economy but the numbers were as good or slightly better than the
typical Lycoming powered RV numbers I hear. It is only slightly faster than my
Renesis powered RV-4 at cruise conditions and reasonable fuel flow. But what I
like about it is the effortlessness with which it does the job. There is always
a handful of throttle left for reserve in any normal flight situation.
Full throttle is reserved for those few seconds between rudder effectiveness at
30mph and lift off speed at 60. As soon as the wheels break ground I typically
reduce manifold pressure to 24". Cruise climb is done at between 18 and
19" depending on takeoff weight at around 700 FPM. Cruise altitude was
limited to 15,000 this trip by temperature. I wasn't thinking and wore only a
thin jacket and I don't have cabin heat. All three legs were flown at 14,500 in
a very unusual high pressure system the whole way with almost zero wind. Here
are the raw numbers:
Altitude 14,500
OAT 35 - 43F
TAS 174 - 182 MPH *
Fuel Flow 8 GPH
Engine RPM 5250 - 5450
Manifold Pressure 14.3"
% Power 30% (As calculated by EM3)
EGT 1450F
Water temp 145 - 150
Oil Temp 160 (Cowl flap would help temps and airspeed)
Total flight hours on trip 9.2
* Fuel flow was held constant, TAS varied with fuel batch. Low number was with Florida
gas with about 8% ethanol. Refueled at Charlie England's place (Thanks for the
hospitality and fuel service Charlie!). Not sure wether it had ethanol or not
but TAS was a few MPH better. After refueling at 47K in Kansas
with no ethanol mogas, the TAS reached the highest number.
Tracy
Sent from my iPad
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