lowNslow wrote:The O200 engines for Formula One are supposed to be stock. They way they get more HPs is to use a short prop and wind the engine up to 4000+ rpm.
WOW! They must really scream!
Most of us know that props lose efficiency at very high RPMs, partly because the tips go supersonic and the boundary-layer leaves them due to the shockwave. Shortened tips address part of that..but shortened props also are less efficient due to the simple loss of airfoil surface.
The high RPM (within reason) doesn't (or shouldn't) hurt our O-300s too much. After all, these same cylinders, pistons, rods, bearings, etc etc were used in the geared GO-300 which turn in the 3,200 RPM range and produce 175 HP.
But to deal with the propeller loss of efficiency, they put a gearbox on the nosecase to reduce prop RPM. So the engine
was allowed to turn up in the 3,200 range (and even higher) while the prop still turned in the 2700 range. Those props were pitched greater as well, and later engines even used constant speed props.
Regardless, it was an unpopular engine. It's higher RPM resulted in lower TBO (1200 vs 1800 hrs), more noise, more fuel consumption, and more expensive overhauls due to that gearcase. Flight schools did not enjoy them due to the fact that simple training manuevers were hard on the gearcase. (Stalls, especialy accelerated-stalls, Lazy-8s, steep turns, etc. placed high gyroscopic loads on the gears and resulted in increased wear. Pilots inexperienced with geared engines failed to keep them "spooled". The frequent power changes and descents under low power/reduced power caused the prop to "drive" the engine and chatter gears.)
Plus, the airplanes in which it was installed (Cessna SkyLarks, T-41s, etc) did not have much greater performance. A C-175 was called a "baby 182" by it's owners, but it only eperienced about 5-7 kts improved speed over the standard 172. Despite what I heard, my several hundred hours of personal experience in them demonstrated a 110 kt cruise speed, vs the standard 170/172 cruise of 105. (It takes lots more HP to move the same airframe faster due to the old rule-of-drag that increases at the square rate-of-velocity.) That was hardly a good trade considering it burned another 2 gallons or so per hour and lost 600 hours of TBO.
The field performance also failed to show improvement because they were heavier, partly due to that engine and partly due to unuseable fuel, the result of misshapened tanks and higher fuel-volume certifiation requirements. Cessna did their best to put lipstick on it but it never caught on, and only barely fit into a niche between the 172 and the 182. Yeah, it was a "baby 182" all right.....it had 182 operating expenses at 172 speeds and useful loads.
Cessna tried to lower the purchase cost in order to move them off the lot by cutting corners. Cessna introduced acrylic paint (a la automotive paints) and stopped interior corrosion-proofing. This reduced labor and matl's costs, but it resulted in filiform corrosion under the paint and interior surface degredation. That, and the engine, made the used-airplane sell cheaper and attracted lots of secondary owners to it.....whom were looking for low-cost flying. Unfortunately most of those type owners gave even less mx attention to an airplane which clearly needed MORE....not less.
Those engines are rapidly falling into the junk-piles now because there simply are NO thrust bearings available. No one supports that engine
That was my experience....and I actually LIKE the airplane. I was a "psuedo" partner in one for about 5 years and spent many days/hours working on it.
