Re: Benefits of streamlining Happy New Year


Mike Perry
 

Mike wrote: "As you descend the load on the prop is less so the RPM
increases, this in turn increases the power out of the engine." You
could stop the engine then stop the prop -- that would minimize the
variables. It also raises the risks (will the engine restart?), so only
do that over somewhere you are sure you can land. Anyone with access to
a dry lake bed?

(One of my former instructors taught me that in engine out situations I
should raise the nose until the prop quits windmilling. It does seem to
give better glide ratio. Yes, he made me practice it with the engine
stopped, within glide range of the field. Engine restarts were easy.)

FWIW -- Mike

On 1/3/2011 6:42 AM, Mike Dwyer wrote:

There are too many variables. As you descend the load on the prop is
less so the RPM increases, this in turn increases the power out of the
engine. Each prop performs differently. So now you got a throttle
setting variable, a prop variable, an engine power variable.

Best to drag a Q over to the NASA wind tunnel.

Straight down with power on the Q200 will probably go 500 mph? Would
probably get to 350 mph before the control surfaces depart the
airframe. I've been at 250 TAS in a slight descent.

Mike N3QP Q200

Sam Hoskins wrote:
Jay, this sounds like a neat idea. I might take you up on the test.

No way, however, am I going to point the nose straight down. :>)

Sam

On Sun, Jan 2, 2011 at 10:05 AM, Jay Scheevel <scheevel@...
<mailto:scheevel%40bresnan.net>> wrote:


Charlie wrote:

."Some one could do the dive test with a GPS to plot the L/D =
Velocity h/

Velocity v = slope of the exponential curve. Point one straight down I
think the wall will be a lot higher than 220 MPH. I have been at 180
indicated in my old Dragonfly coming down final for a low pass with
55 hp.
Low drag and cubic horsepower proceeded by cubic dollars equal winning
plane. Just my

$.02 and opinion not backed by facts."

Sometime back, I challenged folks with flying Q's to give this a
practical
test and help put some numbers on the chart. Jim always says ".Now Go
Fly!". Who would like to follow his advice and send me some
airspeed vs.
decent rate numbers..See my previous comments below...

"1 horsepower corresponds to 542.5 foot pounds/second (or about
32550 foot
pounds/minute). So if you put your plane, loaded to something like 1000
pounds, into a steady 1000 fpm descent rate and the speed
stabilizes to 220
mph, then you are adding .30.72 horsepower. If you had to go to
2000 fpm to
get up to 220 mph, then it would be adding 61.5 additional
horsepower and
so
forth. So if you think your plane should fly 220 mph, then find the
descent
rate necessary to achieve this speed, then compute how much more
horsepower
you would need.

It would be fun to make a chart of airspeed as a function of decent
rate
(holding the engine settings constant at level cruise settings). If
this
chart was done for every flying Q out there, then we could see the
range of
effective performance for each unique airplane. Compiling this info
would
also make a very effective follow up to my wing incidence study and
I would
be happy to do it.

...what do you think guys? Could you gather me some more data to
analyze???"

Cheers,

Jay Scheevel - Tri-Q, still building











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