Posts by jmeyn
1 - 9 of 33 Posts
Joined
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780 Posts
Do-it-yourself drag calculation
If you know the top speed and the engine speed at that point, and you have a dyno chart, it's easy.
1) Drag is proportional to the square of velocity
2) At top speed, drag is equal to available thrust (pounds) which is torque times overall gear ratio divided by wheel radius (in lb-ft, and ft)
3) You can get the torque from the dyno chart and the tire diameter from the tire specs. After computing the drag you can get a helpful factor for computing drag at any speed by dividing top speed drag by the square of the top speed. For fully faired race replicas this factor is around 0.01 lb/v/v.
A rough estimate of drag at 200 mph for a 600 RR is 200*200*.01, or 2*200, or 400 lb.
If you know the top speed and the engine speed at that point, and you have a dyno chart, it's easy.
1) Drag is proportional to the square of velocity
2) At top speed, drag is equal to available thrust (pounds) which is torque times overall gear ratio divided by wheel radius (in lb-ft, and ft)
3) You can get the torque from the dyno chart and the tire diameter from the tire specs. After computing the drag you can get a helpful factor for computing drag at any speed by dividing top speed drag by the square of the top speed. For fully faired race replicas this factor is around 0.01 lb/v/v.
A rough estimate of drag at 200 mph for a 600 RR is 200*200*.01, or 2*200, or 400 lb.
Joined
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780 Posts
Faulty assumptions
I don't currently have a Honda. I never said any Honda could do anything. I asked if something was possible. Noone is answering.
You seem to know. How do you "stap on some nitrous" on a Honda with very sophisticated electronic emission and fuel injection hardware/software. Contributions are welcome.
I don't currently have a Honda. I never said any Honda could do anything. I asked if something was possible. Noone is answering.
You seem to know. How do you "stap on some nitrous" on a Honda with very sophisticated electronic emission and fuel injection hardware/software. Contributions are welcome.
Joined
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780 Posts
Re: Do-it-yourself drag calculation
1) The result is consistent with reality within about 5% either way in several speed tests on modified motorcycles and right in line with MotoGP bikes that have exceeded 200 MPH.
2) 5% is all you can expect given the difficulty of reaching and measuring top speed; repeated runs tend to vary that much.
3) Bikes are out of boundary layer flow and into turbulent flow from about 5 mph till the edge of the speed of sound. The method holds quite well over that range.
1) The result is consistent with reality within about 5% either way in several speed tests on modified motorcycles and right in line with MotoGP bikes that have exceeded 200 MPH.
2) 5% is all you can expect given the difficulty of reaching and measuring top speed; repeated runs tend to vary that much.
3) Bikes are out of boundary layer flow and into turbulent flow from about 5 mph till the edge of the speed of sound. The method holds quite well over that range.
1 - 9 of 33 Posts
