Sport Class speed potential

[CubersWrist]

Re: Sport Class speed potential

We do consider flutter. I think last year we were doing 450 down the VoS.
The Legacies (stock and racers) have been dive and flutter tested to these kinds of speeds. And #30 got the tail wrapped with several more layers of carbon to stiffen the tail.

Also the original post mentions the class has stagnated over the last 10 years. I know it's been about that long since Sharp retired from racing, but it only "looks" like speeds have stagnated. Looking only at Jeff's speeds you might think he has gotten slower when he is actually getting faster. This all goes back to the course was different pre-ghost and the timing was different pre-2016 or whenever that was. You sort through all that goblety gook and you find there is still a progression.

But even more telling than looking at the top speed is the class average. Now I couldn't tell you what that is, because that's a lot of data, but qualifying is probably easiest to use.

Lastly, the potential speed of the class is something I don't really care about. I just care about being the fastest on Sunday. But that being said, as long as I come back from Reno with things I want to improve, the answer is, we can still go faster.
And we are already working on stuff so I guarantee we can still go faster.

[planecrazy2]

Re: Sport Class speed potential

Very fun thread. Thank you all for your varied insite.

So....What speeds could we expect if we ditched recips and used turbines? Cheaper in the long run, way more dependable=safer, no need for a large fluids cache, no adi.

I cant get the picture of Relentless with a fitted turboprop unit bending the pylons.

Just imagine the speed of a new purpose built Sport class turboprop! 500 does not seem out of reach?

[Race5]

Re: Sport Class speed potential

Very fun thread. Thank you all for your varied insite.

So....What speeds could we expect if we ditched recips and used turbines? Cheaper in the long run, way more dependable=safer, no need for a large fluids cache, no adi.

I cant get the picture of Relentless with a fitted turboprop unit bending the pylons.

Just imagine the speed of a new purpose built Sport class turboprop! 500 does not seem out of reach?

Turbo props would provide all the entertainment of the jet class. ZZZzzzzzzzz

[gp70442]

Re: Sport Class speed potential

I think last year we were doing 450 down the VoS.

If you are going 450 in VoS to post a 40x race speed, a 450 race speed becomes all the more daunting.

Looking only at Jeff's speeds you might think he has gotten slower when he is actually getting faster.

I neglected to take into account the post Ghost course changes. My bad.

Thanks for the info.

GP

[Race5]

Re: Sport Class speed potential

We do consider flutter. I think last year we were doing 450 down the VoS.

Any thoughts of going for the 3k in class? I'd love to see you guys smoke some of Sharp's records.

[planecrazy2]

Re: Sport Class speed potential

Turbo props would provide all the entertainment of the jet class. ZZZzzzzzzzz

What do you find entertaining about air racing Race 5?

Is air racing “boring” to a deaf person?

I thought this was all about speed. Not necessarily "entertainment”.

Speed in its purest form.

To me, air racing has been a threefold effort for speed, airframe, pilot skill and powerplant.
Why limit ourselves to “how much horsepower can we squeeze out of a 1000cc or 200cc or whatever class size recip. engine before it blows”, in the powerplant category?

The potential is there to have the sport class evolve into a Super Sport class with turboprops.

And what about the inevitable electric class? Is it doomed to fail because all you will hear is prop noise?

What will air racing be like in 50 years? You and I will be dead and gone, but I know we both want there to be air races in the year 2070.

I would bet WWII era aircraft won’t be racing in 2070. Perhaps Race 5 might even be powered by a small turboprop unit that your granddaughter 3D printed in her bedroom.

Cheers,

[Lockheed Bob]

Re: Sport Class speed potential

Its like they never thought they could break the speed of sound or go to outer space. Kelly Johnson(Lockheed) & Von Braun had the foresight to advance aviation & space travel to prove the short sighted wrong. All of you involved with advancing air racing should continue to do so. By the year 2070 they will probably have Outer Space Races.

[Reever]

Re: Sport Class speed potential

Who says I won't be at the races in 2070?????????? I think 112 is doable.

[Stewartspony]

Re: Sport Class speed potential

Sport Class speed potential is a balancing act between thrust, drag, lift and weight (gravity). To maximize thrust you have to increase the torque output of the engine and utilize a propeller that can efficiently transform the torque into thrust. Increasing the torque output of the engine invariably requires additional heat rejection, wether the engine is air cooled or water cooled. This addition cooling requirement will come at the expense of increased drag. Air cooled race engines rely on a sufficient supply of slip stream air forced into the cowling as well as the latent heat of vaporization of a cooling liquid sprayed on the cylinders and into the induction system. The weight of the liquid coolant is countered by increasing the lift of the wing which increases induced drag. Liquid cooled Race engines rely on air/liquid heat exchanger exposed to the slip stream as well as spaying an additional liquid over the cooling tubes to increase the efficiency of the exchanger.
These cooling requirements all increase the total drag on the airframe. Air cooled engines have an advantage in that their cooling capacity relys more on spraying a liquid than forcing air over the cylinders. Liquid cooled engines must have a heat exchanger exposed to the slip stream and suffer the result of the increased drag. However, the liquid cooled engines are all “geared” engines, that is they use a propeller speed reduction gearbox to reduce the propeller speed in relation to engine speed. Consequently, a 540 cubic inch V type liquid cooled engine with a 2:1 prop speed reduction effectively has twice the cylinder swept volume of a 540 cubic inch Lycoming with a direct drive propeller. The liquid cooled engine will be heavier and more complicated that the Lycoming, but it’s torque potential will be much greater. Here is where the balancing act comes in. The speeds at which the top tier Sport Class racers are flying, drag reduction is tremendously important. To increase the aircraft’s speed, you have to widen the imbalance of thrust versus drag by maximizing thrust and minimizing drag increases. At what point will a heavier, increased drag, liquid cooled engine racer producing substantially more torque, be faster than a lighter, slicker, air cooled racer? Don’t know myself, but I would love to see a 1200 HP forced induction Thunder Mustang try.

[Samuel]

Re: Sport Class speed potential

I wonder how long it will be until someone runs an engine that is closer to the 1000 cubic inch limit? Seems like the IO-720 isn’t the ticket, so it would probably have to be developed from something else