RenaatXS
Active Member
Hi There.
Today I did a propeller test with some different props to find the ideal prop for my engine.
At one point, my engine ran 3480 RPM and gave 76 kgs (170 pounds) of thrust with a certain prop (dimensions unknown, somewhere around 16 pitch, dia 48).
When my friend tried the very same prop on his Honda GX670 engine, he ran 3400 rpm, but this gave only 60 kgs (130 pounds) of thrust.
This I do not understand: Why doesn't the same prop at about the same rpm on a different engine give the same thrust force? Those engines are different for sure, mine has more torque and maybe a little more HP, but I always thought this didn't matter when you're able to reach the same rpm. My tacho has a measuring resolution of 60 rpm, so it might be possible that mine was running a bit more than 3500 rpm. But does this 100 rpm difference result in 16 kgs more thrust?
In my point of view, if you put engine X in a car and run it at 3000 rpm, it'll do let's say 60mph. And if you put engine Y in the same car and run it at the same rpm in the same gear, it should run 60mph aswell right? Please explain this :emb:
Picture:
(The upper engine is the subject. My gocart where it's mounted on serves as a movable test bench)
Today I did a propeller test with some different props to find the ideal prop for my engine.
At one point, my engine ran 3480 RPM and gave 76 kgs (170 pounds) of thrust with a certain prop (dimensions unknown, somewhere around 16 pitch, dia 48).
When my friend tried the very same prop on his Honda GX670 engine, he ran 3400 rpm, but this gave only 60 kgs (130 pounds) of thrust.
This I do not understand: Why doesn't the same prop at about the same rpm on a different engine give the same thrust force? Those engines are different for sure, mine has more torque and maybe a little more HP, but I always thought this didn't matter when you're able to reach the same rpm. My tacho has a measuring resolution of 60 rpm, so it might be possible that mine was running a bit more than 3500 rpm. But does this 100 rpm difference result in 16 kgs more thrust?
In my point of view, if you put engine X in a car and run it at 3000 rpm, it'll do let's say 60mph. And if you put engine Y in the same car and run it at the same rpm in the same gear, it should run 60mph aswell right? Please explain this :emb:
Picture:
(The upper engine is the subject. My gocart where it's mounted on serves as a movable test bench)
