Re: Density Altitude, Q200 Speed


Allan Farr
 

Wouldn't the official race speeds already be corrected?


From: Mike Perry
Sent: Wednesday, November 10, 2010 4:55 PM
To: Q-LIST@...
Subject: [Q-LIST] Density Altitude, Q200 Speed



Mike, I still don't see how you get a correction of 17 mph. If you use
QACs chart of speed vs. altitude (newsletter 20) a density altitude of
6000 ft gives you a speed correction less than 10 mph. DA of 3000 ft
gives a correction of about 5 mph. Those corrections would move
Malechek's speed up close to 220 (QACs claimed top speed) but they don't
give you 230-240.

Am I missing something? Is there some other way of correcting the speed?

Sam, If it was a standing start then I am truly amazed, and possibly 230
is achievable. Anyone want to do a speed run in Death Valley below sea
level on a cold winter morning?

Mike Perry

On 11/9/2010 5:32 PM, Mike Dwyer wrote:

Yup, March in FL is about 80F, 60 F dew point, and they're probably
1000' feet up.
See: http://wahiduddin.net/calc/calc_da.htm
That gets you a density altitude of 2800' here in FL!
Mike Q200 N3QP

Mike Perry wrote:
Mike:

You are the engineer, but I don't get it. Sun & Fun is about 150 ft
elevation, Guys who are racing usually fly as low as possible unless
wind is a big issue (I think this was a triangular course so hard to
think they flew high). Was the temp that high?

I see what you mean about correcting to standard conditions, but do you
really think that gets you 17 mph from race conditions?

Mike Perry

On 11/9/2010 3:36 PM, Mike Dwyer wrote:

But... these are actual speeds. By the book the max speed for a
normally aspirated engine is at sea level, 29.92 inches pressure
altitude, and 59F. If you took that 213 mph and calculated it to
"standard" he would probably be doing 230+?
Mike Q200

Sam Hoskins wrote:

At the 1999 Sun 'n Fun 100 mile race, Bob Malechek turned 212.99 mph
in his

Q-200.

Tom Moore was right behind him at 205.27 mph. I was behind Tom at
187.80
mph.

This was my very first race and I hadn't fully grasped the need to fly
on-course. This is also the race where I asked Bob the now legendary
question "What throttle setting do you fly at?"

These are the fastest times that I know are documented.

Sam

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