I am flying my first air race next week at Leicester. I am doing it together with a friend in his Cirrus SR22 Turbo. It is the Tornado Alley TN version, the SR22 TN. You fly against your own handicap speed after flying first an octogon pattern where the aircraft handicap is set. So, this happens to be the aircraft we are flying next week, but we do not have the pretention to win. We could loose from a slower plane it that one will also fly against its handicap speed.
During the air race, it is the idea to fly a race track around turning points for 30 minutes at approx. 700 feet AGL and at full speed. There are a lot of safety and other issues to consider, but I want to focus here on the engine performance and the turbo (turbocharged / turbo normalised).
Will it hurt the engine if I fly for 30 minutes at full power at 700 feet around several turning points?
Any ideas and tips on how to keep the engine running properly?
Will it hurt the engine if I fly for 30 minutes at full power…
Charter customers who hire aircraft at a “wet” hourly rate do that all the time, for hours and hours and hours, not just 30 minutes…
… but perhaps not so very low? Not hindered by lots of knowledge (again!) I should sthink that as long as all temperatures and pressures remain within limits all is ok.
Even going a step further: my famous namesake would perhaps never have gained fame had he always remained within limits. To win races one needs to go beyond, and either know very well what to do and how, or be a bit lucky.
A colleague is an avid air racer with a few victories to his name – he mentioned that an Auster used to compete, and also win, but to make the minimum 100mph speed requirement (am guessing it was one of the smaller, lower powered versions), the engine would need a fair bit of TLC after each season.
Agree that if operated within limits there shouldn’t be an issue. I assume @what_next is tongue in cheek – turbines are routinely operated as high and as close to max continuous, conversely the Alaskan engine life optimizer is routinely used on big bore Continentals (C-185 and C-206) in bush flying – a clothes peg on the throttle to keep you from going to full power.
The consensus view of Cirrus owners on COPA is that two things will reduce your engine’s life expectancy: flying with CHTs above 380F (with 400 as an absolute limit) and TIT above 1600F.
That stems from the metallurgic properties of the steel that is used in the cylinders, which will lose half its strength at around 400F (IIRC).
Probably, running full rich full power would generate enough cooling airflow to stay within limits. I’ve never tried it at 700 ft, but a continuous climb to FL180 takes around a half hour, and the TN’s engine can take full power during that period whilst remaining within the temps mentioned above at only 120 KIAS (gradually increasing to 125 at altitude).
If your friend is prepared to overhaul his cylinders and change his turbo, then you can of course disregard these limitations and use those set forth by Continental.
PS: have you tried if you can reach 2000 ft with your energy reserve after an engine failure, taking maybe 4 seconds reaction time, and what your speed would be there? That would be the height that I would want to be at to be able to deploy CAPS with confidence.
That stems from the metallurgic properties of the steel that is used in the cylinders, which will lose half its strength at around 400F (IIRC).
According to John Deakin, I think that refers to the aluminium, but still it is probably a bit more than 400F. I have a book of his somewhere, with some diagrams.
If the race is not longer than a typical climb it should not be too bad. How about the IAS? Our plane would be way past redline if we did full power in low and level flight. I don’t know the rules but why not limit the power to a predefined manifold pressure as you are flying against a reference speed anyway? Else in a race without handicap you have to know the screws which control the turbo boost and the max rpm, tape the panel and flap gaps…
Since you are not racing against anyone but your self I do not understand why you wish to fly at full power.
We are racing against others and the first one that crosses the finish line wins. However, to make the playing field fair to everyone, the slowest aircraft starts first and the fastest the latest. To figure out your starting position (handicap), you have to fly the octogon pattern together with a race official in the cockpit first. He is there to make sure you fly full throttle and as fast as you can. The aircraft is equipped with a satellite tracker. After flying the octogon pattern with the official next to you and the satellite tracker mounted, they run the results of that pattern through software to establish your handicap and start position.
Just let us know the tail number, so that when this Cirrus comes up on the used market, we can avoid buying it. 
