underbody cover

[Austria]

Hi
Did anyone install an underbody cover, to prevent smoother air flow under the car?

[JeepFlyer]

Here's a link to the other forum...

Click Here (http://www.ffcars.com/forums/17-factory-five-roadsters/292746-aerodynamatics.html)

I think this is what you're looking for.

[tirod]

I take it you might mean, to "promote" smoother undercar airflow, ie, to use a undertray diffuser, or in older American hot rodding terms, a belly pan.

While it's a subject of interest to me, the majority of builders seem to be replicating the car as it was in 1965, when most of the aero work was yet to be discovered. The Daytona Coupe was a huge step forward in vision. The 818 project seems to have a number of interested potential builders who have a perspective geared to incorporating that. The GTM includes it, I believe.

Roadsters? Not so much.The standard roadster body wasn't known for it's high speed aerodynamics, and that is entirely the reason Pete Brock designed the Coupe. An undertray on the Roadster has the deck stacked against it. Those who campaign on the track or race circuits generally have a lack of long straightaways to provide an incentive, unlike most of the European circuits. Despite the huge expanse of America, tracks with Mulsanne straights are a rarity. We run more short courses, I believe so the track owners can amplify the number of seats for which they charge admission. :)

I've searched, there's a dearth of builders with any interest in serious aerodynamic work. I've found most of the internet links are touring car based - a roof is necessary to really achieve higher speeds. The American roadster builder isn't concerned with actual performance, they are oriented to replicating a vision of what they think was a performance car in that era - before electronics, aerodynamics, and computer aided drafting and analysis intruded with reality - the GT40.

That leaves the field completely open for new pioneering work. The Cobra was completely bypassed and remains in a vacuum, so to speak.

[Austria]

Here's a link to the other forum...

Click Here (http://www.ffcars.com/forums/17-factory-five-roadsters/292746-aerodynamatics.html)

I think this is what you're looking for.

Yes, the guys know what they are talking about, but.... can not get in contact with them (registration fail...)

[Austria]

The "belly pan" is more a optical thing to me, else it would bring seconds on the track. I am running classic track days and not real races.
I want of it that the water spray when driving on wet roads stays out of my engine bay and of course have a racer look, nothing more.
Need to know how are the fixing points done and which locker for fast remove should be used, the materials...
Thinking of carbon plates.

[skullandbones]

I take it you might mean, to "promote" smoother undercar airflow, ie, to use a undertray diffuser, or in older American hot rodding terms, a belly pan.

While it's a subject of interest to me, the majority of builders seem to be replicating the car as it was in 1965, when most of the aero work was yet to be discovered. The Daytona Coupe was a huge step forward in vision. The 818 project seems to have a number of interested potential builders who have a perspective geared to incorporating that. The GTM includes it, I believe.

Roadsters? Not so much.The standard roadster body wasn't known for it's high speed aerodynamics, and that is entirely the reason Pete Brock designed the Coupe. An undertray on the Roadster has the deck stacked against it. Those who campaign on the track or race circuits generally have a lack of long straightaways to provide an incentive, unlike most of the European circuits. Despite the huge expanse of America, tracks with Mulsanne straights are a rarity. We run more short courses, I believe so the track owners can amplify the number of seats for which they charge admission. :)

I've searched, there's a dearth of builders with any interest in serious aerodynamic work. I've found most of the internet links are touring car based - a roof is necessary to really achieve higher speeds. The American roadster builder isn't concerned with actual performance, they are oriented to replicating a vision of what they think was a performance car in that era - before electronics, aerodynamics, and computer aided drafting and analysis intruded with reality - the GT40.

That leaves the field completely open for new pioneering work. The Cobra was completely bypassed and remains in a vacuum, so to speak.

That's a pretty nice account of the development of the two iconic racers. But I must differ with you about your statement regarding performance, " The American roadster builder isn't concerned with actual performance, they are oriented to replicating a vision of what they think was a performance car in that era - before electronics, aerodynamics, and computer aided drafting and analysis intruded with reality - the GT40." I have no misconceptions of what I am replicating. It isn't a vision of what I thought but rather it is what it is - a bad a** hot rod just like all the other muscle cars I've had before it. It may be a replica but it out performs cars of that era as some recent match ups have shown. The aerodynamics are of little importance to its performance and that is the point. Shelby wasn't concerned with that at first (hp to weight ratio was good) until the speeds (150+) exposed the critical weakness of the roadster. So if I was trying to improve the performance of the roadster on the track, I would go for air dams, a wing, ground effect panels, louvers in the tops of the fenders but a belly pan wouldn't help just as you pointed out. But for most of us who are building roadsters (IMO), performance is the number one reason for doing it. By the way, the GT40 is one of my favorite cars of all time. WEK.

[tirod]

A belly pan won't shield intrusion from rain in the engine compartment. That's going to happen no matter what, by driving thru the radiator core. Then a belly pan will trap the hot air and moisture under the hood. If it's sufficiently sealed up, it will block the radiator flow egress to the point the car overheats.

Air thru the radiator has to come out somewhere, and air needs to flow over the motor, too. Underhood components are usually capable of handling temps up to about 240 F. Above that, they fail. It's why starters get heat shields to protect them from exhaust headers. It can be done, it needs careful consideration. Here's an English language link that explores some of that: http://www.autospeed.com/cms/A_2159/article.html

Shelby knew he was getting away with poor aerodynamics. Most American racetracks are comparatively short, and the Cobra could muscle it's way around with superior horsepower to weight ratio. We could burn the gas because it only cost us 15c a gallon, while Ferrari was paying $1.50 or more overseas. We could take advantage with low cost production motors. That in and of itself is no parameter of performance alone, and the Friday night cruising Main Street experience most of us shared points that out - when it came to high speed events, the Cobra can't cut it. Period. All the muscle in the world won't help a brick when the horsepower needed goes up exponentially for each ten miles an hour faster.

When it came to beating Ferrari, Pete Brock showed the way by getting a body on an AC chassis, same 289 motors as all the other cars, and adding another 40mph to the top speed. So while aerodynamics might not be crucial to cruisers wanting to rip some pavement downtown, when adults gather to test the real limits of auto performance, aerodynamics is crucial.

The 289 powered Daytona Coupe brought home the FIA championship, not a 427 Cobra. Being all bad a**d doesn't necessarily bring home the bacon.

[skullandbones]

Did you see the thread with the for sale roadster racer with a belly pan and 650 hp? I can't beleive it has a underbody cover but everything else about it is serioius racing (Nascar Grade). By the way, the roadsters brought home plenty of bacon themselves. I'm not arguing against aerodynamics in this thread just that this belly pan idea is not good. I haven't heard any support for it either (nice link on pressure gradients). Also, you need to understand that in the realm of performance, the range is from 0 to 300+ mph. So it depends on who you talk to as to what they see is necessary for attaining that goal. For instance, TF dragsters use massive hp and some aero to get to that 300+. Others see 0 to 100+ mph as a goal or enough power and aero to get around a track in a certain time. Personally, I want to be a member of the 200+ mph club (already 160 3 times) but I can promise you it won't be in a roadster. I think I could see me doing 200+ mph in a coupe or something similar at Bonneville. I think the performance limits for the my roadster will be between 0 and 125 mph and that will be limited to the drag strip or other area that I can do it safely. No hard feelings, I hope. WEK.

[Austria]

Hi skullandbones
no, I didn`t see the thread. I am still thinking of just an optical (not sealed) belly pan. Still not know which locks are used.