Piston Speed

[Exhaustgases]

Then there are some recip engines that can run into the 32,000 rpm range and piston speed is still in the 1666 feet per minute range.

 

[MolaKule]

Then there are some recip engines that can run into the 32,000 rpm range and piston speed is still in the 1666 feet per minute range.

What engine is this?

Generally speaking, the higher the RPM the shorter the stroke.

The Cox 010 model plane glow plug engine is a 2-stroke engine capable of 35,000 rpm but its stroke is only 0.226 inches and its piston speed is about 1,318 ft./min or 22 ft./sec. at a top RPM of 35,000 RPM.

Shaft HP is about 0.03 HP.

Not much use as a daily driver.

 

[CDNozzle]

You learned it in high school?

I suppose that tells you what the kids are learning in high school these days (even when I was there 20 years ago)

I didn't learn dimensional analysis until mechanical engineering school -- and it's one of the few things from college that I continue to use on a regular basis!

Yeah pretty much just in Chem 1 when needing to find limiting reactants, converting molecular weights, using ideal gas law, etc.

I used it a lot more when I dual-enrolled in a comm college physics class . It's particularly handy for physics students who like to solve problems 100% in variable form before substituting any numbers. My MechE/AeroE brain can only handle so many letter variables

 

[Exhaustgases]

What engine is this?

Generally speaking, the higher the RPM the shorter the stroke.

The Cox 010 model plane glow plug engine is a 2-stroke engine capable of 35,000 rpm but its stroke is only 0.226 inches and its piston speed is about 1,318 ft./min or 22 ft./sec. at a top RPM of 35,000 RPM.

Shaft HP is about 0.03 HP.

Not much use as a daily driver.

Yes your correct, I just did a quick search and got the wrong stroke number.

And yes that was the one I was referring to.

 

[CR94]

Love dimensional analysis. Despite how simple it is (or it can be), it blew my mind in high school when I first saw it in chemistry.

It's helped me solve many problems in undergrad before I even start writing down variables.

Yes. I first learned about that in high school chemistry, too---then in every subsequent science and enginering class. Generally, if you haven't set up your calculation so the units work out correctly, the answer will be incorrect.

 

[RDY4WAR]

The generally accepted maximum mean piston speed (in the racing world) for common forged components is 82 ft/sec (25 m/s). Beyond that, it gets a little dicey. You start looking for lighter rod design/forgings, thinner pistons to cut down weight, etc...

An engine with a 3.5" stroke would reach that limit at ~8500 rpm.