Paul,

Here's some video data for you.  http://www.youtube.com/watch?**
v=dZrADAieO6w <http://www.youtube.com/watch?v=dZrADAieO6w

It was taken this morning with a Flip video camera during my takeoff run
and
climb to about 4k msl.  OAT was 78.  Initially, the mixture was set the
same
as my last report as indicated by the EM-2's mixture bar.  Then I adjusted
the mixture a bit richer, toward "best power".  Best I can tell, the fuel
flow went to 28.6 gph.  Sorry for the shaking as I was both the pilot and
the cameraman.  I stopped recording when the sun blanked out the EM-2's
screen.  I need to design a camera mount before I try this again.

Prop was set to 2100 rpm for initial takeoff, then to 1900, and finally to
1700.  Max engine RPM (that I can read) was 6926, but dropped back to
approx. 6350 as speed increased, prop still at 2100.  You can hear engine
rpm drop when I changed prop setting.

It should be noted that the primary oil and water temps are on the EFIS,
not
the EM-2.

Mark S.

Good work Mark. Thanks for the data. I discovered Mike did not install the
4 push button sw's on my EM-2 so I'll have to do that to read that kind of
data.

At a BSFC of .6 that is 286 HP. Not bad for only 6336 engine RPM. I get
2223
prop RPM with a 2.85 gear. Why do you set the prop RPM so low? What is the
tip speed at 2223 RPM on a 76 inch prop?

What is wrong with the EM-2 display? It looks like mixture bars are over
writing
the text.

Sounds like you need a set of David Clarks for your video camera :)


Paul Lamar

Glad you found that exercise of interest.  I need to either, 1) build a
camera mount, 2) put some tape over the mic, and/or 3) have someone else do
the filming while I fly the airplane.

Regarding prop rpm, sometimes I use 2150, but normally I set it at 2100 prop
rpm because it works without over-revving the engine.  Tracy has the EC-2
rev-limiter set at 7500 rpm.  The M/T electric prop adjusts very slowly.
When I first start feeding in the power the rpm goes to 6900-7000rpm as
seen in the video.  It doesn't come down until I'm a good ways down the
runway.  I may try 2200 and feed the power slower and see how that works.
Or, start out with it set to 2100 and then re-set it once I'm rolling.  At
2100 it climbs at 1300-1500 fpm, so that works just fine for Texas.  I don't
want to cause my pax any nosebleeds.  BTW, I was carrying 80 gallons of
100LL in the video.

According to my calculations, the prop tip speed at 2223 would be about 737
fps.

Mark

It was very informative. I screen captured half a dozen at different
RPM's.

Speed of sound at sea level = 1116 feet per second
so that is only .66 Mach. Try setting the prop at 2400 RPM.
You cannot over rev a rotary with a prop connected.
It sounds like there is too much pitch at the start of the
take off roll.

The Rolex 3 rotor RX8 car's used to run 10,000 RPM for up to 24 hours
before the race organizers put a 8500 Limit on them to make
everybody else competitive.

I think if you do that you will shorten the take off roll.

80 gallons is 480 pounds of fuel. ES empty weight is supposed to
be 1900 pounds and gross weight 3200 pounds.

That is a much better ratio than a C182. Max fuel on my C182 is 88 gallons.
If I lean it very carefully I can get the fuel burn down to about 13 gallons
an hour but I am only doing about 140 Kts. A used C182 is about 100K
and a new one half a million :)

Paul Lamar