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Monday, May 7, 2018

Jeremy "More Power" Clarkson

Jeremy "More Power" Clarkson
The post isn't about Jeremy Clarkson. It's just that I needed a title, "More Power" seemed appropriate, but I can't say "More Power" without thinking of Jeremy Clarkson, so there we have it.

Piper Twin Commanche

I'm sitting here in the backyard, taking it easy after a hard day of being retired. I'm sitting here and every few minutes a small airplane flies over. Not too surprising, we live about a mile from the Hillsboro Airport, the second busiest airport in Oregon, not that that's saying much since there is only one real-international-fly-anywhere-in-the-world airport in Oregon: PDX.

Anyway, these small planes are flying over and they are making noise, as small planes are want (wont?) to do. And I'm thinking these guys are really struggling. They have the biggest engine they can afford / that the plane can carry, the engine is working as hard as it can, and they can't afford the loss of power and lift that carrying a decent muffler would cost them.


3.0-Liter V6 Twin-Turbo 400-HP Engine | INFINITI Q60 Coupe | INFINITI USA

What we need is a better engine. Maybe we should be using automobile engines. Automobile engines are getting crazy powerful these days. 300 horsepower out of small displacement V-6 is common. But we don't need 300 horsepower, we have that in existing Continental and Lycoming engines. What we need is 1,000 horsepower. No, make that 2,000. You can never have too much power.

Why should you need that much power in an airplane? Cars can go just as fast as small planes, and they generally have more power (200 vs. 100 HP). Because we are taking a big step up. 500 MPH is not just 5 times as fast as 100 MPH, it's 100 times as fierce. It's like the difference between chucking rocks at beer cans in your backyard and hitting a watermelon at a thousand yards with high-powered rifle.

Now I'm wondering why piston engines for airplanes have stagnated. Jet engines certainly haven't. And then I realized that the decision to pursue jet engines was made by the military and the military wanted speed and power, hang the cost. They didn't want to be distracted by two different engine development programs. They went with the one that promised the most power the soonest.

Spitfire Merlin engine replacement*

So what's the difference between a Merlin V-12 that was used in a Spitfire and a modern 1,000 HP conventional reciprocating engine? I suspect there isn't any one thing you could put your finger on, rather it's anything you touch. Everything is different, subtly, you wouldn't notice anything if you weren't intimately involved with the design. Oil, materials, machine techniques, just everything, but the end result is that a new 1,000 HP engine would weigh a fourth of what a Merlin weighs. (Okay, that might be pushing it. If anyone knows different, let me know.)

African Homebuilt Airplane

There are some people in home-built, experimental airplane circles who have been putting automobile engines in airplanes with mostly positive results, but commercially the small airplane industry is stuck in 1950. If it wasn't for the FAA, there would be more progress in aviation. So maybe the answer is to go someplace where the FAA isn't. Africa, I'm looking at you. Here's your chance to build your own FAA, one that isn't bogged down in bureaucratic bullshit. You could be a force in the airplane world. Yeah, right. Fat chance of Africa ever managing to get their shit together.

But maybe that's the way of future, total government incompetence, who you trust based entirely on rumor because nothing you hear from the media can be trusted. So you buy your car / house / airplane based on what the guy at the gas station said, and the only products that succeed are the ones from giant corporations that can afford a massive guerrilla marketing campaign.

Okay, I got a little distracted. The point I was trying to get to is why are propellers so large? A 100 hp engine swings a propeller that is as large in diameter as a good size jet engine. The one thing I hear when I ask this question is 'efficiency'. Well, screw efficiency, what we want is more power. The speeds modern car engines are like the speeds that jet engines turn than the prop speed of a 1000 HP Merlin. Maybe what we need is a small, high speed fan connected directly to a high speed engine. You are going to need some duct work since the blast from the small diameter will be directed directly at the engine. You might be able to generate enough thrust just from the suction, but it would be nice if you got a kick from the blast as well. Directing it at the engine will ensure that it is wasted. It might not be as efficient as a propeller, and it would require some fancy ductwork, but you wouldn't need the speed reducer, a heavy thing that might break.
Pratt & Whitney Speed Reducer
Looks remarkably like the ones used in WW2 radial aircraft engines

On the other hand, Pratt & Whitney is stuffing their old WWII speed reducers in a jet engine in order to lower the speed on the fan. Or maybe we go electric: engine drives generator, generator drives motor. No gears. No mechanical connection except for a couple of fat cables. Works like magic.

Of course if we really knew what we were doing, we would be using electric power to push the air past airplane directly through some kind of magically, subatomic, quantum mumbo-jumbo.

*this picture only exists inside of a search engine. I got it from Google, who claims it comes from Pinterest, but Pinterest claims it came from Google.

2 comments:

Ole Phat Stu said...

Chuck, may I point you to the PFM 3200 Porsche engine :-
https://en.wikipedia.org/wiki/Porsche_PFM_3200

Anonymous said...

You are comparing peaches and bowling balls, I think.

Boils down to reliability and economics. There is no place to pull over to the side of the road if your airplane engine fails, so you do everything you can to make sure it doesn't quit and the FAA helps you. That's reliability because I don't want to be the first one to the airplane wreck as the pilot.

Now the economics. There are only a few airplanes built each year. 2016 General Aviation Manufacturers Assn. says 718 piston engine aircraft were built in the U.S. The biggest years in the last few decades only saw like 16,ooo built and that was only a few years. There are supposedly 210,000 GA airplanes in the U.S., the vast majority being single engine piston powered, and about 218 million automobiles. In 2015 and 2016, record setting years 16 to 17 million cars were sold in the US. For every airplane there are 1,000 automobiles. How much would a car cost if 718 were made each year?

That is capital cost out the door, here is maintenance. GA piston engines generally have time between overhauls of 2,000 hours or so. If that was your car at an average speed of 35 mph at 70,000 miles you don't do another oil change, you take the engine out and put a rebuilt one in. The instruments and electronics in your car are used to entertain you and tell you how fast you are going. In your airplane they tell you to not go low enough to fly into a stuffed cloud, which direction you are going and where you are relative to a airspace features, the ground, the airport you are going to, etc. They are painstakingly designed and certificated to assure they do what they are supposed to and nothing else, and they still aren't perfect. Wait until we have self driving cars and you will see what happens when consumer automotive standard quality electronics are used in a safety critical role and see how many casualties there are.