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Cool article about the Dan Wasdahl/Joe Cheng Phantom's wings being upgraded.  An estimation of 333lbs downforce at 50mph from updated wings was mentioned. To bad nothing about the underbody.

Anybody care to speculate how much downforce the underbody gives?

Marlin

zexel:

 

 Anybody care to speculate how much downforce the underbody gives?

 

At 50mph, around 50 to 150 lbs., depending on design, size and who you ask.

Marlin, you have been asking A-Mod questions for the last few years, have you started working on a car yet?

Joe

Hi Joe,

Yes, I am building......painfully slowly due to family (2 year old twins and a 4 month old and we both work full time).  To quote someone  with racecar experience: "I'm 80% done with 80% to go" excluding the aero package and the years of developement.

http://s221.photobucket.com/albums/dd280/Bailor_AM_Special/

Not much to show yet but anybody/everybody: critique away please!!! 

Marlin

 

zexel:

 

 critique away please!!! 

 

I do have one. Insulate the garage.  Doesn't it get cold in Ohio?

Yamaha sled motor?

Joe

Marlin- I'm bad with names- did you stop by my garage last year, and did I talk to you

at the smackdown at northfield the other week? I was looking at your pictures, and thought we discussed

a reworking of a fsae car with a swing axle setup...

 

dan w

Joe - yes Yamaha RX1 motor.

Dan - I talked to you in 2004.  I took pictures of the Phantom at Toledo.  My car has pullrod suspesion all around.

Marlin 

 

Ah. Good. Using mountain bike shocks?

dw

They are Yamaha R1  (1000cc) bike shocks.  Likely not the best choice.  Anybody know how stock sportbike compare to MTB shocks, and to low end formula car dampers?

Marlin

zexel:

Not much to show yet but anybody/everybody: critique away please!!! 

I don't have a critique to offer at the moment, but do have a few questions:

 

1) Is there a reason why you went with box tubing instead of a forward roll hoop at the front of the cockpit?

2) How did you arrive at the wing area split of ~ 8 square feet front, and 12 square feet rear?

3)  Is the fuel tank (???) on the bottom right shelf something that you fabricated, or is it a standard part on some other vehicle?

 

Just curious, since you're about 75% further along building a car than I am.....

skunkworx:

zexel:

Not much to show yet but anybody/everybody: critique away please!!! 

I don't have a critique to offer at the moment, but do have a few questions:

 

1) Is there a reason why you went with box tubing instead of a forward roll hoop at the front of the cockpit?

2) How did you arrive at the wing area split of ~ 8 square feet front, and 12 square feet rear?

3)  Is the fuel tank (???) on the bottom right shelf something that you fabricated, or is it a standard part on some other vehicle?

 

Just curious, since you're about 75% further along building a car than I am.....

 

1. I don't have a tubing bender and it allows more dashboard space and possibly more knee room climbing in and out. (The roll bar is the only part I didn't make myself)

2. My design copies the Phantom in many places.  Those dimensions are very similar.  It seems to make sense to divide up the 20sq ft. that way.  The front gets clean air and ground effect.
3.

It is a standard racing kart 5 quart. 

Feel free to email or PM me for any info about mine or the limited info on the others that I have.

Marlin

zexel:

1. I don't have a tubing bender and it allows more dashboard space and possibly more knee room climbing in and out. (The roll bar is the only part I didn't make myself)

I had the same problem making a roll hoop on my last project.  If there was a company that bent custom mail-order 1020 hoops, I'd be welding next weekend!

zexel:

2. My design copies the Phantom in many places.  Those dimensions are very similar.  It seems to make sense to divide up the 20sq ft. that way.  The front gets clean air and ground effect.

I had already arrived at the same ratio on my own (and for almost the same reasons), but was wondering if you were taking anticipated corner weights into account or something else that I might have missed.

 

The desirability of having the front wing in ground effect would probably make an interesting message thread, because I thought that I read somewhere that it was a bad idea due to the unpredictable loss of downforce on rough pavement.

 

zexel:

Feel free to email or PM me for any info about mine or the limited info on the others that I have.

I will definitely take you up on this offer in the the near future.....

While I can't see myself ever building my own car, I'd love to see that conversation happen on this thread instead of via mail / PM just to see the considerations which occur when designing an A Mod car...

Ditto

---

James Lambert

I tried throwing them away but the garbage man said that the city was not allowed to dispose of charred primates. I told him that I had a wet one. He couldn't take that one either. I didn't bother asking about the frozen ones.

PedalFaster:

While I can't see myself ever building my own car, I'd love to see that conversation happen on this thread instead of via mail / PM just to see the considerations which occur when designing an A Mod car...

As a tool for increasing class participation numbers, I couldn't agree more that laying out the basics of A-Mod car design would be beneficial to everyone.  If you look around this very forum, there's threads detailing the selection of final drive gearing, tire sizes, and now an actual CAD sketch of a workable wing package thanks to Marlin.  It's a good start for someone who wants to do their homework, but not quite a FAQ.

I would like to hear from others who have already built cars about where they started with the design process.  Since aero seems to be a primary key to success in A-Mod, my thinking is to start by laying out the wings and ground effects first, and then "connect the dots" with a chassis built around them.  Is this a correct way to start a scratch design?????

skunkworx:

As a tool for increasing class participation numbers, I couldn't agree more that laying out the basics of A-Mod car design would be beneficial to everyone.  If you look around this very forum, there's threads detailing the selection of final drive gearing, tire sizes, and now an actual CAD sketch of a workable wing package thanks to Marlin.  It's a good start for someone who wants to do their homework, but not quite a FAQ.

 

I think it would be great for A-mod and the sport in general to open the doors to the A-mod world and let some light shine in.  I am sure that most of the A-mod guys communicate via email or subscription email list.  If these discussions could be held here where people outside the group could see it, there might be a few more poeple willing to take the plunge. 

I think a lot of people assume things are harder than they are when there is a lack of information available.  Case in point, when I migrated from DSP to DP I heard from a number of people who said they would love to run Prepared but couldn't justify the cost and/or didn't have the fabrication skills.   Well, that isn't necessarily an issue.  Costs for building my DP were about the same as my DSP car,  I just spent the money in different places.   I also had learned a lot from my mistakes on the DSP car which saved me money on the DP car.  I probably fabricated about the same number of parts for each car.  Again, different parts but about the same number.   So their perceptions were quite wrong and if they had known, maybe they would have considered running prepared.

Also, while I don't have any intention of running in A-mod anytime soon, I love reading the technical discussions.  And sometimes there is even stuff that is relevant to something I am working on for my own car. 

---

Steve Hoelscher
#27 DP - Toyota MR2
2006 DP National Champion
'98, '99, '00, '02 DSP National Champion
http://www.terriehoward.com

Front wing in ground effect over bumps: I'll take all I can get and learn to drive around it.  The loss of downforce won't result in me crashing at 200mph.

We should start a new thread or two.

I have the most of my design in SolidWorks 2006.  Anybody is welcome to it.  Since it was converted from CadKey 99, it is not done any where near properlyor complete.  It is an unproven/untested design; users beware.

Marlin

Steve Hoelscher:

I am sure that most of the A-mod guys communicate via email or subscription email list.

If they do, I for one don't know the address or secret handshake to join that group.

Steve Hoelscher:

Case in point, when I migrated from DSP to DP I heard from a number of people who said they would love to run Prepared but couldn't justify the cost and/or didn't have the fabrication skills.

 

I heard the same argument for staying in the stock classes, because it is supposedly the cheapest place to play.  I don't know about you, but fielding a stock class car capable of trophying in Topeka set me back 5-figures over two years.  When I looked at our local club "elders" living on social security, they were all running prepared/mod because it was significantly cheaper.  The only benefit that I have ever found to owning a stock class car is that banks will gladly finance the purchase of a new car whenever the SCCA decides to mess with the stock classes and leaves your old car obsolete.

Several years ago, I read an article somewhere saying that it cost around $10K-$15K to build a top-caliber A-Mod car.  If this is true, it sounds like a bargain to me.  As for fabricating skills, we all have to learn some place.....

 

 

skunkworx:

Steve Hoelscher:

I am sure that most of the A-mod guys communicate via email or subscription email list.

If they do, I for one don't know the address or secret handshake to join that group.

Steve Hoelscher:

Case in point, when I migrated from DSP to DP I heard from a number of people who said they would love to run Prepared but couldn't justify the cost and/or didn't have the fabrication skills.

 

 

Several years ago, I read an article somewhere saying that it cost around $10K-$15K to build a top-caliber A-Mod car.  If this is true, it sounds like a bargain to me.  As for fabricating skills, we all have to learn some place.....

 

 

I would say $10K would get you a good set of wings for a top-caliber A-Mod car...

---

Erik Strelnieks
93 3-ROTOR RX7
01 Honda S2000
05 SLK 350 AMG

I should have mine running for about $10k.  It is not top caliber.  Without a turbo and EFI, I will be down more than 100HP - maybe 200HP on the 2 strokes.  Without data aquisition, I will never get it fully developed.

A top caliber car will have more than $25k in parts and materials.  Design, labor, and development value?  20- 50- 100k?

From hooperraceengines.com:   1465 Predator-2 - 320 H.P. $7395 using your stock bottom end
Details: Includes - Complete top end, all case mods., crank stroking and balancing
*Big carbs. and flanges not included

Marlin

ErikZ06:

I would say $10K would get you a good set of wings for a top-caliber A-Mod car...

 

See, that leaves you $5K to buy a good used snowmobile to mount them on. 

I couldn't build my DSP car for $15,000.

While I am no expert on building competitive A-mod cars, for the most part, once you are into the realm of prepared and mod cars I don't know that there is a significant difference in building one class of car from another. Save the wings in A-mod, engines, transmissions, fuel systems, chassis, suspensions all have similar components and costs. 

When I bought my DP car is was already a DP car but not of the caliber I wanted.  I redid the entire car; completely new engine, transmission, clutch/flywheel and engine/transmission mounts.  New suspension: Shocks, arms, bushings/bearings, camber plates, etc...  Misc:  New seat, harness, steering gear, instrumentation, wiring harness, etc...  I could have spent tripple what I did if I had really wanted to throw the budget out the window.   The return on investment couldn't justify the additional expense at this point.  Not to mention the time and money budget were going to be stretched if I went that way.

Of course this doesn't factor in labor, engineering and fabrication skills, or time.  Or other variables like what engine you choose...

 

---

Steve Hoelscher
#27 DP - Toyota MR2
2006 DP National Champion
'98, '99, '00, '02 DSP National Champion
http://www.terriehoward.com