Done driving for the year

[pgfpro]

Thanks for both your posts.

I'm trying to get this done this weekend (I only get one weekend off every month)so all the advice is very much appreciated.

I just measured the bottom angle up and it came out to be 28 degrees.

If I make the top around 15 degrees the bottom will be close to 15 degrees also. Is this a better way to go then then 11 degrees top with 28 degrees bottom?

[Christ]

Bottom has minimal airflow, I'd worry more about keeping the top attached. 15* may do it for you, though.

Best to set up a test bed type of mod, that you can tweak and test, rather than going all out on the first iteration, just for this type of question.

I do think that 28* on the bottom is way too steep to even think that airflow will stay attached, so it might be OK to break cleanly, rather than try to keep attached flow. I assume the front will have a lowered stagnation point, so there will be less than normal airflow under the car as well, correct?

[pgfpro]

Originally Posted by Christ

Bottom has minimal airflow, I'd worry more about keeping the top attached. 15* may do it for you, though.

Best to set up a test bed type of mod, that you can tweak and test, rather than going all out on the first iteration, just for this type of question.

I do think that 28* on the bottom is way too steep to even think that airflow will stay attached, so it might be OK to break cleanly, rather than try to keep attached flow. I assume the front will have a lowered stagnation point, so there will be less than normal airflow under the car as well, correct?

Yes the front bumper is only 4" off the ground. Plus I'm adding even more front lip so it will sit around 1" off the ground. The side skirts will be around
1" also.

[Bicycle Bob]

"Yes the front bumper is only 4" off the ground. Plus I'm adding even more front lip so it will sit around 1" off the ground. The side skirts will be around 1" also."

That sounds like a maximum downforce setup. I suppose it might be useful on ice, but it will probably raise rolling resistance.

[Christ]

Originally Posted by Bicycle Bob

"Yes the front bumper is only 4" off the ground. Plus I'm adding even more front lip so it will sit around 1" off the ground. The side skirts will be around 1" also."

That sounds like a maximum downforce setup. I suppose it might be useful on ice, but it will probably raise rolling resistance.

That would be a nail-biter setup around here... I've seen guys with 3-4" of clearance trash their bottoms out here, and I rode around with about 2" for awhile, but I decided it was just too hard to negotiate every pebble in the road at the correct angle and raised the 'Scort back up.

[pgfpro]

OK I think I will leave the bottom clearance at 4".

I thought that the idea was to keep as little air from going under the car. I was wrong this aero stuff is killing me.LOL

The only time I will need down-force would be at the track and the hill climb.

For the most part it will be used for hopefully 1000 mile road trips across the great western United States. I will be mostly on the Interstate Freeway system but you never know when I have to stop to get food etc. what the roads will be like.

So today I will see what a 15 degree drop roof angle will get me for the bottom rear piece.

[Christ]

Check out the nose of vetter's streamlined bikes - it's curved at the nose to allow some air to still get under the vehicle. Not much, but you need enough flow to fill the space between the car and the road, else you get the same effect as the wake behind the vehicle, which will create downforce by means of a vacuum under the car as the air rushes over and around the vehicle, but not under it to equalize the negative pressure.

No matter what you end up doing, make sure it can be changed without too much frustration, because after you test it, you may reveal a weak point in your design, such as a portion with detached flow or a turbulent vortex.

Hey, you never know.

[pgfpro]

Originally Posted by Christ

Check out the nose of vetter's streamlined bikes - it's curved at the nose to allow some air to still get under the vehicle. Not much, but you need enough flow to fill the space between the car and the road, else you get the same effect as the wake behind the vehicle, which will create downforce by means of a vacuum under the car as the air rushes over and around the vehicle, but not under it to equalize the negative pressure.

No matter what you end up doing, make sure it can be changed without too much frustration, because after you test it, you may reveal a weak point in your design, such as a portion with detached flow or a turbulent vortex.

Hey, you never know.

Check out the nose of vetter's streamlined bikes

I just looked at his bikes. I think I'll raise it to 5" and start there.

I wish I could do some testing with my setup, but now may engine is apart so I can't drive it. But I should have it back running in about a month.

[Christ]

You promised inside the engine pics! Let's have 'em!

[pgfpro]

Originally Posted by Christ

You promised inside the engine pics! Let's have 'em!

I will have a ton of pics at a later date with a thorough write up on my engine design.