I remember some report of a race team (NASCAR, I think) going for a
speed record on a banked closed course. Report was that the car, which
was supposedly very successful in races, overheated fairly quickly when
run flat out. Supposedly, the off-throttle time during racing is very
significant in reducing total heat load of the engine. Again,
supposedly, no such luxury is available in a/c. Is there any validity in
the story or concepts presented?

Airfoil for 2400lbs @200mph: How about, find someone building an RV-10 &
copy that?

Charlie

 

It is possible if it was a short track setup being done as a lark. The superspeedway cars are flat out at close to 100% duty cycle. Slowing only for danger or pit stops. Typical revs around 7,800 to 8,000 RPM. Short track engines are run over 9,000 RPM. But short tracks require quite a bit of off throttle time. They also think things like 260 oil temps and 240 water temps are OK.

 

As the new driver gets better, the cooling gets worse. Because you are not cutting down lap times with both feet on the brake pedal. Learning the limit of adhesion in all situations is the drivers job. Hopefully learning it all in one chassis.

 

My friend Joe Salyer (1960 Bonanza with a 550) entered his Chevron (290HP 1,500 pounds) in a CanAm race at Mid Ohio years back. In practice he went as deep as he thought he could into the braking area at the end of the long back straight. While he was on the brakes as hard as possible, his mirrors turned red and Allen Jones ( X formula one driver) in a bright red Chevy powered Lola rocketed by still at top speed, whipped in front of Joe, waved a thanks (for not pulling in front of him) dynamited the brakes and vanished around the tight right hander.

 

Joe determined that there was more braking power available than he was using.

 

The long spooldown braking period seen in the novice lap, is all but missing in the pro lap.

And so then, is the long, off throttle period that reduces the heat load on the radiator. As off throttle time goes down, duty cycle closes in on 100% and the true cooling capacity of the system becomes apparent.

 

While racing can pinpoint a fault in a power system by overstressing it. Racing cannot duplicate the duty cycle of the aircraft installation.

 

The more modern teams NASCAR, now lease engines from just a few engine builders.

The development dynos are running constantly, and the computers can and do replicate an entire race at any track they choose, including a blocked radiator opening, overheated coolant and oil, and every pit stop.

 

You seldom see one drop out from just engine problems.

 

The aircraft installation has a total stress level that is a bit lower than racing, but the support systems are loaded at a higher level on a time basis. So it is the support systems that need the work. In general, the engine will be fine at any output level.

 

Lynn E. Hanover