"bhtooefr" (bhtooefr)
10/22/2018 at 05:19 • Filed to: rotary, adams-farwell
3
13|
"bhtooefr" (bhtooefr)
10/22/2018 at 05:19 • Filed to: rotary, adams-farwell | 3
| 13 |
Rotary engine car , but not the modern definition.
Nauraushaun
> bhtooefr
10/22/2018 at 05:22 |
|
Aren’t they called radial engines?
|
bhtooefr
> Nauraushaun
10/22/2018 at 05:31 |
|
Rotaries (pre-Wankel) have a radial cylinder configuration, but they differ from what’s commonly referred to as a “radial engine” in that the crankshaft is fixed and the crankcase spins, instead of the crankshaft spinning and the crankcase being fixed.
There’s a reason I used a video instead of a picture.
Cé hé sin
> Nauraushaun
10/22/2018 at 05:33 |
|
Yes. They were a thing on planes around a hundred years ago.
|
Nauraushaun
> bhtooefr
10/22/2018 at 06:37 |
|
Oh jesus. My bad, I gave it a watch. It seems a ridiculous idea! They talk about unsprung mass ie. rotating mass as a bad thing, why waste that energy spinning the whole engine? And the pistons
have this crazy battle against centrifugal force! They’re getting thrown to the outside of the radius constantly! All for cooling?
|
bhtooefr
> Nauraushaun
10/22/2018 at 06:57 |
|
It was a popular thing through World War I for aviation engines , because they ran very smoothly, they didn’t need a separate flywheel (and therefore they were lighter), and they cooled well even at idle.
Also note that engines back then spun slower, 1200 RPM max was typical of a rotary... but it was also typical of other aero engines at the beginning of WW1. Once you started spinning faster than that, the rotary’s disadvantages became extremely apparent.
|
Nauraushaun
> bhtooefr
10/22/2018 at 07:10 |
|
Cooling? Is that really necessary when you’re flying through the air?
shop-teacher
> bhtooefr
10/22/2018 at 07:26 |
|
That's freaking bonkers!!!
|
bhtooefr
> Nauraushaun
10/22/2018 at 07:33 |
|
It’s necessary when you’re sitting on the ground with the engine idling, waiting for takeoff.
TheRealBicycleBuck
> Nauraushaun
10/22/2018 at 07:34 |
|
Yes. Think of it this way. The more horsepower generated, the more heat generated. If the goal is to maximize horsepower without water cooling, then it’s best to maximize airflow around the cylinders. Moving the cylinders through the air is an excellent way to accomplish this.
There are lots of other issues introduced, but it’s good to remember that this was an age of experimentation and learning. Now we have computers to simulate it, but back then, the only way to find out was to build it and see what happens.
On airplanes, the rotating mass would cause excessive amounts of p-factor. Think of it as a big gyroscope at the front the airplane. Any inputs are resisted by the gyroscopic factors caused by the spinning mass. However, there are engine designs with rotating cylinders, rotary pistons, and counter-rotating shafts which provide enough opposing forces to virtually eliminate p-factor. https://patents.google.com/patent/US6761144B2/en
McMike
> bhtooefr
10/22/2018 at 07:47 |
|
Wouldn’t the prop wash at idle
cool a fixed, radial engine?
|
Nauraushaun
> TheRealBicycleBuck
10/22/2018 at 17:05 |
|
Oh that makes sense. I suppose that’s true as long as cooling is the ceiling you’re hitting. Fascinating stuff. Particularly around the need to build rather than simulate.
Rusty Vandura - www.tinyurl.com/keepoppo
> bhtooefr
11/04/2018 at 22:43 |
|
There were some aircraft engines like that.
|
Rusty Vandura - www.tinyurl.com/keepoppo
> bhtooefr
11/04/2018 at 22:46 |
|
That thing looks dangerous.