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Old 09-25-2019, 01:33 PM   #21
rotorwrench
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Default Re: AvGas in the ford

I started out working on the Hughes 269 series helicopters and the 269C has the HIO-360-D1A engine. They wanted max horse power for normally aspirated operation and they wanted a high RPM rating. This is about the only 10:1 ratio small engine that I'm familiar with. The Enstrom helicopters were set up for higher HP with a Lycoming 360 type but they are turbocharged to get the power so they have a lower compression ratio. The Hughes/Schweizer 269C runs at 3100 rpm in the middle of the green arc but can be run up to the red line of 3200 rpm for short periods so it had to be built well to take that but it only has a 1,500-hour TBO and it won't last much more than that without some problem cropping up. For an aircraft engine, it's a hot rod but it takes a beating when you have two big heavy cowboys in there and a full tank load of avgas. These engines are a 4-cylinder opposed type so you know by the displacement of 360 CID that they have some big pistons in there.

High compression aircraft engines are a rarity. Most are 8.7:1 or less. Props run at around 2,700 to 2,900 rpm so they don't really need higher capability than that. The old Lycoming 435, 480, and a few other engines would run up to 3400 rpm but they had to have prop reduction gearing to go that fast. Props don't need to go supersonic at the tips. The blades can't take that.

Just to ADD: Helicopters run at a very narrow RPM range to keep the main rotor rpm within design limitations. The small ones with belt drive have pulley combinations to get the engine to optimum rpm for power (torque) while the main rotor is at optimum rpm for best lift. Power setting vary depending weight in the aircraft and whether it is in climb mode or descend mode. In that respect, they are about the same as an airplane, Full power would be when you have a full load and are climbing out at a high rate. As soon as it levels off, it uses less power. In a decent, the power drops of to little or nothing due to good old gravity. In a hover just above ground level, they have to deal with ground effect so they use a lot more power in a hover than they do at a level cruise speed or hover up out of ground effect. I don't like to hover way up there. I like to keep moving so I know it can go into autorotation normally if something happens.

Last edited by rotorwrench; 09-25-2019 at 01:58 PM.
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Old 09-25-2019, 01:57 PM   #22
Jeff/Illinois
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Default Re: AvGas in the ford

Quote:
Originally Posted by 40 Deluxe View Post
That's a new one on me! I have read many accounts stating that Philips 66 was so named because they were so proud of selling gas with 66 octane.
Badpuppy, Keith, and 40 Deluxe I've heard all the same stories about how Phillips 66 got it's name, plus another one.

As the story goes, they were out testing Frank Phillip's new gasoline in (what old car I don't recall it was 1927) and someone commented as they were speeding down the road 'Feels like we're doing 66 (MPH)'.

Who knows just what happened, but the water cooler talk among the older guys back then was probably all they wanted for exposure, marketing, etc.

One thing about that 100 Octane + AvGas that WOULD be good for a Model A is, you could store your car with a tank full of it for a long time and it wouldn't break down or separate like today's junk gasolines do.
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