Streamliner Design

[jacksoni]

I like the modification as well but also agree with Stainless. When I built my car I basically copied the main structure and body from Don DeBring's car but with the nose more following the Goldenrod design. I have a couple of papers about LSR aero and the design of the Goldenrod in particular you may like. If you like I could fax or scan and email them. PM me if you want for contact info. The articles are SAE papers, old but interesting in general with a lot in the Goldenrod one.

Specifically, some air under the car is not necessarily bad but the Goldenrod designers specifically wanted at least 50% of the air going around the sides and less over the top to help avoid front lift. I think the tested (but ended not using) a nose design with a vertical, rather than horizontal tip as the 4 sides came together. I ended with a vertical junction about 4-5" to accentuate the flow around the sides. The car never was twitchy, has been over 300mph and included a run where a front tire blew at some speed ( I was not driver on that one) and it did  not upset the car at all. Basic shape was tapered as was Goldenrod and pretty much all liners these days. Lumps and bumps are not good either.

[John Clutch]

To me the nose is not going to work.  Looks like it would split a lot of air under the car... Narrowing the sides will split the air around not above and below.  Nish streamliner showed this when they changed the nose.  The sharp point needs to be more rounded...
Now, to clarify... I am not an aero guy... so that is just my opinion...

Stainless, thanks for the suggestions. Maybe if I explain my thinking on this would help me learn more.

DISCLAIMER: IM NOT A AERO GUY EITHER. I HAVE NO FORMAL SCHOOLING ON THE SUBJECT. ALL MY THOUGHTS COME FROM GUT FEELINGS AND WHATEVER THE PEANUT BUTTER CUPS TELL ME TO THINK 

The nose comes to a  sharp points My thought is that is the air's 1st contact point on the body. Im talking about the very first point. And since its very small, that actual point would create the least amount of pressure in front of the body. The pressure points would start within the body's boundaries. I actual DONT want the sweep into the belly pan. I want a tunnel. But if I cant have one, and Im forced to run a belly pan, why not keep the  transition as smooth as possible instead of a more blunt radius at the nose? Wouldnt it help keep the air attached sooner to the body than a more blunt radius? Im sure the air will seperate under the car regardless but my thought is the blunt radius would make that issue worse.

The height from the point to the belly pan is 3" . Aside from the aero, I felt that was just enough to keep the nose from digging into the salt like a lawn dart if the front tires let go. I would rather not create any high pressure areas transitioning under the body but its unavoidable. Volume under the body is 15%

 My thoughts is a tunnel would create the least amount of pressure, if the entrance and exit geometry was exactly the same. Again, the peanut butter cups is telling me that.

The fenders taper is 50% of the body's width. I feel this would create the smallest width of high pressure air, below the centerline of the wheels Again, I dont know, gut feeling and peanut butter cups.

Thanks.

[John Clutch]

Again, I have no formal training on the subject but I do have a few principles about it that works for pretty much everything on earth.

1. If the air doesnt have to contend with it, its not a problem

2. Fluids do not like change whatsoever. The least amount of shape, the better.

So in my original design, I did every I thought I could about creating the least amount of change. So whatever the frontal profile was at the front, it carried out to the back, ending in somewhat of a point. The roof was the same height and tapered in and the main body section was the same height and tapered in.....

Then I realized volume comes into the play as well. The body was taking up too much dead space in the rear and adding to the surface area, so lets trim the fat there. Thats when I tapered the canopy at the rear, to the main body. I figured the original body would be more stable without a stabilizer, but stabilizers are small and work well, so even a taller stabilizer would take up less volume than how the body was.

[Interested Observer]

Tough to say without dimensions, but I would be surprised if you can get your eyeballs, head, helmet, and roll bar underneath the roof as shown and still be able to see out the front.

[John Clutch]

Tough to say without dimensions, but I would be surprised if you can get your eyeballs, head, helmet, and roll bar underneath the roof as shown and still be able to see out the front.

The top of the fenders is 22". Between the fenders, at the front wheels, the hood tapers down 3". The bottom of my chin is at 22", right at the height of the fenders at the side. Again, the hood tapers down at that point to 3" between the front wheels. The canopy is 7". The windscreen is 5" tall and its mean center is 12" in front of the rollcage hoop, 16" from my eyes. This gives me a total blind spot of the track, exactly 20 feet in front of the car at 1.5" ground mclearance. Is that too much? Am I overlooking something?

[Stainless1]

John, do you have a helmet yet?  They take up a couple of inches of the height you are working with.  If you look at the Bockscar 2.0 build I think I have the top of the cage about 9 5/8 to 9 3/4 inches above the rails that establish the top of the front body.  With that if the car sat level you would not be able to see very close, not that you need to.... but... the rake of the car allows vision about 60 feet in front of the car.

[John Clutch]

John, do you have a helmet yet?  They take up a couple of inches of the height you are working with.  If you look at the Bockscar 2.0 build I think I have the top of the cage about 9 5/8 to 9 3/4 inches above the rails that establish the top of the front body.  With that if the car sat level you would not be able to see very close, not that you need to.... but... the rake of the car allows vision about 60 feet in front of the car.

I see where I screwed up. When I orginally started designing the body, I had the hood in a V shape that was 3" deep between the front wheels and the hood didnt meet the top of the fenders til AFTER the canopy. So the windscreen was 2" lower than the top of the fender at the front. I had the centerline of my eyes at the top of the fenders or 2" higher than the windscreen. Since then I changed the hood to meet the fenders 1" in front of the windscreen. I changed it to simplify the design and make it easier to produce but completely forgot about the view. Now, as is, the hood is right inline with my eyeballs. And to make matters worse, I forgot the damn 1" of rollcage padding.     

[John Clutch]

And thank you all for the help and support so far!!!! I really appreciate it.

[John Clutch]

The yellow line represents the old hood profile. And again, thanks for all the help.

[John Clutch]

John, do you have a helmet yet?  They take up a couple of inches of the height you are working with.  If you look at the Bockscar 2.0 build I think I have the top of the cage about 9 5/8 to 9 3/4 inches above the rails that establish the top of the front body.  With that if the car sat level you would not be able to see very close, not that you need to.... but... the rake of the car allows vision about 60 feet in front of the car.

Do I have a helmet? Yes. But its over 20 years old and one state away. Do I have a new up to date helmet and sock being shipped on the 16th? Thats also a yes.
 

Clutch

[manta22]

Clutch, the new helmets are a bitch to fit into tight-fitting cages where older helmets fit just fine. 

[John Clutch]

Clutch, the new helmets are a bitch to fit into tight-fitting cages where older helmets fit just fine. 

Yes Manta, thats what I assumed. Im nowhere near ready to fabricate anything but figured a new helmet will help push the build. I hope to have the car built before the helmet expires LOL. PLUS maybe a chubby dude wants to put a skinny dude in his salt car for a scoot....  hey....you never know!

[John Clutch]

Raised the canopy 2" to 9"
Lowered the body by 4" to 18" (thanks to Stainless helping me find smaller tires)
Shortened by 6" to 21.5'
Changed the nose profile completely with a sharp 9" vertical seam.
1.5" radius at the top of the fender and bottom of the rocker, transitioning to that 9" vertical seam at the nose.

[John Clutch]

A quickie of the front end for the green car

[kiwi belly tank]

Two things to be aware of in the design process with a lay-down position in a liner, many helmets aren't open enough at the bottom to allow forward vision & the head & neck restraint choice is also limited.
  Sid.