lakester CD ?

[racergeo]

 In the March Hot Rod they wind tunnel test the Hot Rod LSR Camaro. they got a Camaro that in stock form has about a .4 cd down to about .2 or a 50% reduction. That seems just huge. So Im wondering what a lakester with 4 tires and some suspension hanging in the wind might have? Say a car like Hammonds or a more typical tank like the Markley Bros. Any ideas? Any one actually did the math? Thanks

[Sumner]

In the March Hot Rod they wind tunnel test the Hot Rod LSR Camaro. they got a Camaro that in stock form has about a .4 cd down to about .2 or a 50% reduction. That seems just huge. So Im wondering what a lakester with 4 tires and some suspension hanging in the wind might have? Say a car like Hammonds or a more typical tank like the Markley Bros. Any ideas? Any one actually did the math? Thanks

One option is to look at the individual Cd and area of the components you are talking about.

I've seen .4 for wheels/tires a couple places and you can figure the area of them from their size.

The suspension/axles/radius rods/etc. hanging out in the wind can't be better than .4-.5 in my opinion.

The body itself if made as slippery as some of the streamliners maybe down around .09 to .12.  Problem is that depending where the first two items are located in relation to the body they can screw up the Cd of the body (tires by the sides of the body for example).

Seth went with the approach of getting the wheels/tires away from the body and that is what I'm trying to accomplish also along with getting as much of the axles, suspension, etc. inside the body like he did also.  That car set lots of records, but let's also give credit to the engine department and I believe Mike (Dynoroom) was responsible for a lot of the engines.

The approach of tires/wheels in next to the body has also provided good results for a lot of lakesters also, so I guess decide what you think is best and go for it.

I have more comments about my feelings on this on my site here:

http://purplesagetradingpost.com/sumner/bvillecar/bvillecarindexpage.html

and here:

http://purplesagetradingpost.com/sumner/bvillecar/bville%20-%20LSR%20Thoughts-Index.html

c ya,

Sum

[Bob Beatty]

Joe Law's # 355 lakester calculated out to .48 Cd.  Tires hanging out in the wind are UGLY.

[Dynoroom]

That car set lots of records, but let's also give credit to the engine department and I believe Mike (Dynoroom) was responsible for a lot of the engines.
c ya,

Sum

Thanks Sum, I'd love to take credit for Seth's engines but I'm a consultant on that program. Lee Gustafson has been Seth's partner / engine builder for better than 30 years.

[Sumner]

That car set lots of records, but let's also give credit to the engine department and I believe Mike (Dynoroom) was responsible for a lot of the engines.
c ya,

Sum

Thanks Sum, I'd love to take credit for Seth's engines but I'm a consultant on that program. Lee Gustafson has been Seth's partner / engine builder for better than 30 years.

Well I learned something else new today, thanks.  Lee then is a pretty modest type guy as I've spent a lot of time looking at that car and never realized that he built the engines.  Congrats to you Lee on some great engines!!

That seems to be pretty common on the salt as there are a lot of modest people out there and they are a joy to talk to.  You guys going for the first time this summer are going to love it.

c ya,

Sum

[Stainless1]

I can't tell you what our CD is because I don't know, but I can tell you that 167 HP will do 204mph.  The last motor we had on the dyno was the ZX-11, it made 167 and Marty went within 1/4 MPH of that number with every gear change, tuning change and weather change.  Of course it is only 1 reference point on a line, but I'm sure the aero experts on the site can deduce a CD. Now if I told ya that about 80 HP (calculated based on consumption) of N20 made the car go 228, the aero experts could easily arrive at a CD...  Unless the car still accelerating screws up the calculations, didn't have enough room to reach terminal speed. 
OK aero guys, take your hack... 

[Sumner]

I can't tell you what our CD is because I don't know, but I can tell you that 167 HP will do 204mph.  The last motor we had on the dyno was the ZX-11, it made 167 and Marty went within 1/4 MPH of that number with every gear change, tuning change and weather change.  Of course it is only 1 reference point on a line, but I'm sure the aero experts on the site can deduce a CD. Now if I told ya that about 80 HP (calculated based on consumption) of N20 made the car go 228, the aero experts could easily arrive at a CD...  Unless the car still accelerating screws up the calculations, didn't have enough room to reach terminal speed. 
OK aero guys, take your hack... 

What is the frontal area overall, the body, the tires?  Was the HP at the crank?? Rear Wheels??  Countershaft Sprocket (what gear)

And here you though you were done  , but thanks for the info so far   ,

Sum

[dwarner]

Way back in the early 60s I hung with Lee and Bob Noice when they ran a Jr Fuel car. Sometime in there I went to Bonneville with them. Hooked me forever!!

When I finally lined up for my last attempt at the 2 club we were behind the Hammond roadster with Lee driving. We were walking around in our race suits and I thought "how bitchn' is this?, 40 years later and I'm with one of my heros"

We both did the record. While I was pulling off my suit the Hammond clan stopped and hugged, etc. . Needless to say a tear rolled down my cheek.

I love that place and all of you who race, want to race , or spectate.

DW

[PorkPie]

In the March Hot Rod they wind tunnel test the Hot Rod LSR Camaro. they got a Camaro that in stock form has about a .4 cd down to about .2 or a 50% reduction. That seems just huge. So Im wondering what a lakester with 4 tires and some suspension hanging in the wind might have? Say a car like Hammonds or a more typical tank like the Markley Bros. Any ideas? Any one actually did the math? Thanks

The biggest different is, when you check the CD in the wind tunnel, if you got standing wheels or turning wheels.
The CD increase (by a lakester) when you got turning wheels instead of standing wheels.

The CD increase (progressive) also when you increase the size of the wheels - here also the same different between standing and turning wheels - by the turning wheels the CD curve are more progressive than the standing wheels.

By a lakester normally you would say, the CD is better when you got a wider gap between the body and the wheels, depends how your suspension is designed (covered). The #77 Hammond lakester was a exception. he got his wheels very close to the body but his suspension was complete covered by the body, so there was no effect by the suspension - also this cover (body) went straight through from the front to the end. Perfect design but extremely sensitive in the aerodynamic balance (lift) - Seth done his experience with this effect some years ago.

From aerodynamic point of view a lakester is a brick in the air.....

[Sumner]

......................By a lakester normally you would say, the CD is better when you got a wider gap between the body and the wheels, depends how your suspension is designed (covered). The #77 Hammond lakester was a exception. he got his wheels very close to the body but his suspension was complete covered by the body, so there was no effect by the suspension - also this cover (body) went straight through from the front to the end. Perfect design but extremely sensitive in the aerodynamic balance (lift) - Seth done his experience with this effect some years ago.

From aerodynamic point of view a lakester is a brick in the air.....

Hey PorkPie I think we are talking about the same thing, but to make sure.....

 
   
On Seth's old lakester above I would call the wheels wide away from the "main" body.  He did build pods out to cover the suspension and such and maybe that is why you say the wheels are close to the body.  This is the approach I'm taking to some degree.

   

Now on the Dauernheim - Biglow lakester I would say the wheels are in against the body and effect all the air flow down the body sides.



The third example would be something like Anderson & Calvert's more traditional lakester with the wheels somewhat away from the body and the axles/suspension out in the breeze.

Some lakesters might be a brick compared to a streamliner, but my truck and a roadster are bricks  .  Next to a streamliner a lakester has the best chance at a good CdA out there.

c ya,

Sum

[PorkPie]

Sum,

with Seth's lakester - sure he runs a wide axle - but the wheels are still close to the body work - this is what I tried to explain - if some says that this wheels are close.... - and therefore the #77 is a exception - don't forget "English" is my second language and sometimes it's hard to find the right words...

your second picture shows what a "normal" close wheels to the body means - and wheels so close to the body are really disturbing the airflow.

And by the way, a truck (like the Phoenix!) could be much more aerodynamic than a lot of lakester with all his corners and dents in the body......

[racergeo]

thanks for all your response. So if you make your frontal area 15% smaller can you go 15% faster with same power? How much frontal area does the Stainless car have ? How much do the bigger cars with v8s. Can a lakester be tweaked much like the Camaro was in the Hot Rod article? Sum, how much FA are you gonna have?

[Sumner]

........... don't forget "English" is my second language and sometimes it's to find the right words................
And by the way, a truck (like the Phoenix!) could be much more aerodynamic than a lot of lakester with all his corners and dents in the body......

You are doing fine with your English  and if you would only post more I could get better at reading it  .  You should hear my German  .  I "was" married to a German and since we had so many tourists from Germany in the store at the beginning I tried to learn some.  Of course being German she was a perfectionest and if I didn't say something exactly right I heard about it.  I gave up learning from her and learned from my customers.  If people gave adults the same leeway to make mistakes as they do a kid a lot more of us might learn a second language.

I think there might be other cars that can be made with a lower overall Cd than a lakester, but with the lakester you can also work with the frontal area, so I still think a lakester could have the second lowest CdA (note the A) behind a streamliner.

Sum, how much FA are you gonna have?

Should be a little less than 5.5 square feet for the main body and the pods going down the sides (similar to Seth's) 2 square feet for the tires as seen from the front, then you decide if you should add another 2 square feet for the rear ones that are right in line with the front ones.

I figure on getting the tires out there where they will have their own drag, but not much you can do with that although I've looked a little at what F1 does to fill in the air behind the tire and might experiment with that later.  Now the body I'm trying to make with as small a frontal area as possible and trying to make it as aero as possible.

It is easy to say "when I build one of these I'll do this and that and these other guys have left a lot on the table", but when the time comes to fit you, the engine, safety equipment and everything else real life intervenes and you start deviating from that perfect concept you have in your mind.

The most common I've heard is "I'll make the body a neutral low drag airfoil as seen from the top".  Sounds good, but about the only car (and it is a motorcycle) I've seen achieve that is Eric and John's motorcycle streamliner.  The next best are EZ-Hook, BUB 7, Ack Attack, and the Easy Rider Streamliner.  John and Eric's streamliner has some things in it's favor, the two riders/drivers are not big, they run a very small motor, and they are running a motorcycle streamliner that allows smaller cage members.  Try the same approach with a lakester and you have the wheel/tire deal to deal with, suspension or no suspension, axle locators, physical engine size with engines over 1000cc where now the engine might be bigger in frontal area than you are and the safety equipment (especially the chutes) you have to deal with and the car becomes so long that to make it a good airfoil as seen from the top requires the car to get quite wide.  Welcome to the real world  .

c ya,

Sum

[Speed Limit 1000]

How much frontal area does the Stainless car have ?

Stainless drives car 1000, it is 24" wide 16" tall on the bottom about 9" at the canape and about 20 feet long with a 6.25 dia. chute tube on the back. The tires are 18X4.4 front and 20X4.5 rear. It has earned 3 of us red hats and two friends an A license. If it was much smaller we could not get in it. It is the "Bockscar" and holds 7 records.

[Sumner]

How much frontal area does the Stainless car have ?

Stainless drives car 1000, it is 24" wide 16" tall on the bottom about 9" at the canape and about 20 feet long with a 6.25 dia. chute tube on the back. The tires are 18X4.4 front and 20X4.5 rear. It has earned 3 of us red hats and two friends an A license. If it was much smaller we could not get in it. It is the "Bockscar" and holds 7 records.

   

A couple more pictures here:

 http://purplesagetradingpost.com/sumner/bville-cars-4/1000-2006.html

Sum