Heat and qualifications

[RarebearFan77]

Re: Heat and qualifications

Guys please, I guess yall have all forgotten but flux capacitors are uneffected by heat, temp, and humidity!! All in all it seams to be a fine balancing act either way you look at it.... See yall in a week!!!!!!!! Gosh I can't wait...

[AAFO_WSagar]

Re: Heat and qualifications

Guys please, I guess yall have all forgotten but flux capacitors are uneffected by heat, temp, and humidity!! All in all it seams to be a fine balancing act either way you look at it.... See yall in a week!!!!!!!! Gosh I can't wait...

Well that's the Bear's method but at last check, they have the *only* FC on the planet and they are not about to give it up...

[bruce lockwood]

Re: Heat and qualifications

Hotter is better for P51s. But all classes and specific models have different temps that they work best at. Dago liked 88-92 degrees best. As someone pointed out a higher density altitude is partially responsible, but a bigger factor is the raise in Mach number with the temperature. This increases propeller efficiency by reducing Mach related drag on the propeller tips, supercharger rim and on certain areas of the airframe.

As a rule of thumb, we lost 1 MPH for each degree of temperature drop below 90F given the same course flown/winds/power setting and acft. weight. So...... if 3400 RPM and 120" MP equalled a 495MPH timed lap @ 90deg, then we could expect to see a mid to high 470's lap @ 70 deg F at the same power setting.

The critical altitude for Dago's supercharger (-9 blower gears and a -21/23 fan/defusser @3400 engine RPM plus ram air intake) was at apx 11,000 density alt. by which point the carburetor butterflies are wide open. Any increase in altitude from this point means a decrease in MP unless the RPM is increased. So you can see there is a lot of reserve power in Dago to address temp increases.

Hope that answers you questions.

See you at the Races,
Bruce

[Bigger Al]

Re: Heat and qualifications

Thanks for the fantastic explanation, Bruce!! That will make this weekend's spectating much more interesting for me.

[AAFO_WSagar]

Re: Heat and qualifications

Hope that answers you questions.

See you at the Races,
Bruce

Bruce, thanks for jumping in and settling this from your experience! We have a mutual good friend BuckyD.. would love to finally shake your hand and meet you in person..

You will be here this week?

[bruce lockwood]

Re: Heat and qualifications

Hi Wayne,

I'll be there Sat/Sun. Look me up and say HI. Look forward to seeing Bucky, Neal and all the old friends and crew. Cheers, Bruce

[AAFO_WSagar]

Re: Heat and qualifications

Hi Wayne,

I'll be there Sat/Sun. Look me up and say HI. Look forward to seeing Bucky, Neal and all the old friends and crew. Cheers, Bruce

Hey Bruce, I will.. I'm still glowing this evening after watching Steve's son fly what I think might well be the "perfect lap".. power did not sound that high (90" unconfirmed) yet he turned in a 487+ lap...

To say that Steve looked proud would be a huge understatement..

Actually hard to describe but it was sort of a.. concerned pride... Lots of stuff got to be going on in his mind!

Looking forward to meeting you!