question about EZRocket

My O-320 powered Long EZ doesn't climb at 10,000 fpm at Vne.

Actually, Rick, the web site says, "Single engine performance is
similar to a Lycoming O-320 with constant speed prop." So in that
statement they are talking about performance with only one of the two
rockets firing. Even so, the statement is not entirely accurate.

David O -- http://www.AirplaneZone.com

As Dave Barry would say, "an alert reader....".... You are correct in
your observation. The more complex and more correct statement is that
the single engine ground roll and takeoff are similar to an O-320 with
constant speed prop at a low MSL airport. After takeoff, the piston
engine/prop thrust drops with indicated speed whereas the rocket
engines have constant thrust. Also, the piston engine power drops with
altitude.

And the reason for the short airshow routine was because the events
coordinator asked us to keep it short. Otherwise, Dick would have done
a second go-around (which he practiced at Mojave the week before). We
landed with about half of the propellants remaining, which was why we
did the LOX vent after landing and before rolling into the crowd. Too
bad; that second go-around is more impressive at lighter weight.

Glide and landing are similar to a standard Long, except that the
rocket has less drag (the added fuel tank has less drag than the prop
and cooling drag did), and the belly board is less effective ahead of
the fuel tank.

Dan DeLong
XCOR Aerospace

(Dan DeLong) wrote:

Even so, the statement is not entirely accurate.

David O -- http://www.AirplaneZone.com


As Dave Barry would say, "an alert reader....".... You are correct in
your observation. The more complex and more correct statement is that
the single engine ground roll and takeoff are similar to an O-320 with
constant speed prop at a low MSL airport. After takeoff, the piston
engine/prop thrust drops with indicated speed whereas the rocket
engines have constant thrust. Also, the piston engine power drops with
altitude.

And the reason for the short airshow routine was because the events
coordinator asked us to keep it short. Otherwise, Dick would have done
a second go-around (which he practiced at Mojave the week before). We
landed with about half of the propellants remaining, which was why we
did the LOX vent after landing and before rolling into the crowd. Too
bad; that second go-around is more impressive at lighter weight.

Glide and landing are similar to a standard Long, except that the
rocket has less drag (the added fuel tank has less drag than the prop
and cooling drag did), and the belly board is less effective ahead of
the fuel tank.

Dan DeLong
XCOR Aerospace

Yes, Dan, I ran the numbers for a flat 400 pound thrust using the drag
curve of my Long EZ at 1200 lb. Best rate of climb was 2,770 fpm at
130 kt. That's why I concluded, "not entirely accurate". I then ran
the numbers for both engines firing and got a best rate of climb of
8,100 fpm at 185 kt with an aircraft weight of 1200 lb.

As for the LOX vent at Oshkosh 2002, that was something to see. I
think it was you I questioned afterward and you said it really was not
dangerous without some sort of fuel to burn. You (or whomever) said
you had once purposely put a lit cigarette into the O2 cloud -- the
cigarette burned quite rapidly and that was the extent of the effect.

Thanks putting the videos on your XCOR web site. Riding along with
Dick was a trip. I could hear the concern in his voice on that early
run when the engine didn't shut off as commanded, "We've got a major
problem here."

David O -- http://www.AirplaneZone.com

David O wrote in message . ..
(Dan DeLong) wrote:

Even so, the statement is not entirely accurate.

David O -- http://www.AirplaneZone.com


As for the LOX vent at Oshkosh 2002, that was something to see. I
think it was you I questioned afterward and you said it really was not
dangerous without some sort of fuel to burn. You (or whomever) said
you had once purposely put a lit cigarette into the O2 cloud -- the
cigarette burned quite rapidly and that was the extent of the effect.

Putting a lighted cigarette into a LOX tank vent plume would have been
a serious safety violation and we would not have done that. We *have*
done some flammability tests by holding small samples in a GOX plume
with tongs, gloves, and a fire extinguisher standing by. None of the
tests included a cigarette, but I expect the results would have been
as you described.

You may be recalling something that a crusty old engineer demonstrated
for me back in 1974 in the Life Support Lab at Westinghouse. He
started the lesson with "Don't you try this..." and proceeded to light
a cigarette. He then drew a lungful of oxygen from a mask on an
emergency medical bottle by the swimming pool, put the cigarette in
his mouth and slowly exhaled through it. The end of the cigarette got
really bright and it burned its full length in the one exhalation. I
would guess the gas he exhaled was about 60% oxygen because of mixing
with the residual gas in his lungs.

Saw your photos. Nice. I miss living in the homebuilt world, but my
job just takes too much time, and working on my Defiant is too much
like my day job now; it's not relaxing. And my tools are on loan to
XCOR.

Dan DeLong


David O -- http://www.AirplaneZone.com