Rf 117

[Pete.]

Very nice..
Iain re your question "is there a spellcheck on this forum? If you download the Google toolbar it has a spellcheck you can use to check your posts.

[Russ Noble]

Just like everything on your car, that's a bit tricky!

Beautiful job! Does it work....?

Cheers

[Straight 8 Racing]

We borrowed the design from P. P. P. P.... sorry can't say it. So if it does'nt work I plan to sue them.

Iain

[Dalton]

In terms of the changes to spring rate as the suspension (and coil/damper assembly) moves over its travel, this is corrected on some quite simple cars. For instance, the Fraser Clubman, in NZ, has the option of a rocker arm assembly to transfer the front suspension movement to inboard springs where the geometry can be set up to suit, avoiding or minimising the problem.

Dalton

[Dave S]

Hoping this doesn't offend anybody but what a fanstic job. I simply can't wait to see this race bred machine hit the tracks. I bet RF are chomping at the bit to see how this project performs, what an ad for RF. Iain can I ask were your 8 stack set-up comes from? and can we have a heap more pics please.

[Russ Noble]

Hope this doesn't offend anyone either, but Iains RF is as much like a standard RF as V8 Supercars are like their roadgoing Ford and Holden equivalents. It's a pretty long bow to draw to relate any of these to the production version. Good for advertising but no indication of the qualities and abilities of the original product. The public can't see that though.......

Never the less Iain has created a great car here and I am sure success will come his way. Be good to see a GT40 beating all the other exotics again......

Cheers

[sp250]

P P P I think theres an O after that
steve

[Jac Mac]

Anything borrowed from P***** would be a step backwards! Why join em when you want to beat them.

Jac Mac

[Dave S]

Hope this doesn't offend anyone either, but Iains RF is as much like a standard RF as V8 Supercars are like their roadgoing Ford and Holden equivalents. It's a pretty long bow to draw to relate any of these to the production version. Good for advertising but no indication of the qualities and abilities of the original product. The public can't see that though.......

I agree totally. Hence my earlier post regarding the extent of modification
to make this car a real race car. But when anyone asks what it is they will say "It's an RF".

[Dalton]

I'm offended by all this denigration of Porsches (there, I said the "P" word). I happen to love old classic Porsches and just because there are rich ba**ards who race the latest ones and can buy whatever they need over the counter, I don't think we need to spit on all Dr Porsche's children.

But back to the thread, it will be interesting to see how far Iain has got with calculation and theory, and whether he will still need lots of racing development on the track, such as Ross needed. Remember that the original designers had a lot of technology and experience available to them (albeit more primitive than today's), but still stuffed up the prototypes something terrible.

My 2c worth,

Dalton

[Keith Hardy]

Originally Posted by Dalton

Remember that the original designers had a lot of technology and experience available to them (albeit more primitive than today's), but still stuffed up the prototypes something terrible.

My 2c worth,

Dalton

Terribly unfair on the "designers" as the whole shooting match was controlled by committee governed by Fomoco bean counters. Perhaps Toyota would be grateful for "stuffing up" their F1 program so "terribly".

[Straight 8 Racing]

As stated in my opening introduction to this thread I make no apologies for the alterations we have made to this car, we have and will continue to work every angle that is allowable under our category rules. It will have moved the car some way from the "original" RF in much the same way that the 997 Carrera Cup Porsche bears little resemblance to the road going GT3 that it is based on.

I am no expert in the history of the race programme that Ford ran in the sixties but I am sure they also (within budget constraints) worked the rule book.

There is no doubt this car, like most new race cars will require a fair amount of development but I hope that this time around we have created some thing that can be sorted with out structural changes.

Iain

[Pete.]

Originally Posted by Dalton

I'm offended by all this denigration of Porsches (there, I said the "P" word). I happen to love old classic Porsches and just because there are rich ba**ards who race the latest ones and can buy whatever they need over the counter, I don't think we need to spit on all Dr Porsche's children.

But back to the thread, it will be interesting to see how far Iain has got with calculation and theory, and whether he will still need lots of racing development on the track, such as Ross needed. Remember that the original designers had a lot of technology and experience available to them (albeit more primitive than today's), but still stuffed up the prototypes something terrible.

My 2c worth,

Dalton

Dalton I think you winding us up just a teeny weeny bit..

[Straight 8 Racing]

Dave,
The 8 stack has been fabricated in the workshop, the engine builder insisted on a fairly long run of 3" pipe after the collectors (from Burns in the US) and I insisted on less than 95db hence the quite large mufflers. He is in the process of building a system for another car in the workshop that you just have to see, I will take some pictures next time I am over there.

Iain

[Russ Noble]

Originally Posted by Iain Pretty

As stated in my opening introduction to this thread I make no apologies for the alterations we have made to this car, we have and will continue to work every angle that is allowable under our category rules.

Iain

You're building a serious race car and that's the only way to do it. I'm sure the whole forum is waiting with baited breath to see how you go.

Cheers

[Dalton]

Iain,

I'm interested in your approach to aerodynamics on your car. At reasonably high speed some aerodynamic aids have proved useful. I assume you will be using the full opening behind the radiator to relieve air and get some front downforce. Are you planning on using front wings and rear spoiler? Or a particular angle for the car (eg. lower at the front)? Or vent openings in the window over the engine bay, rear undertray, etc.?

Dalton

[Straight 8 Racing]

Dalton,

(Is that Dalton from Wood & Grieve ?)

We have approached the aerodynamics with a good deal of caution, based on the theory of "if it aint broke dont fix it" .

We have made a front air dam to try and clean up the air flow under the car and provide some additional downforce, which I assume will require some additional downforce at the rear to re-address the balance, this is where it starts to get a bit more difficult. I have received advice that for a rear wing to be effective it needs to be quite large and must stand off the body work by at lease 300mm. Our rules do not allow this, I have also been told that the biggest single improvement in Aerodynamics that would benefit this car would be the addition of a rear under body diffuser, once again if I have interperted the rules correctly we are not allowed to do this. So we will be carefully trying the front air dam to see how it affects the handling but I am no more than 50% convinced that it will be of any benefit without the corresponding downforce at the rear of the car,

Regards

Iain

[dennism]

Hello Iain

Interesting thread for me since I have been following the aerodynamic GT40 revisions since the first Ford announcement way back when
I am not an aerodynamicist, I'm an architect and the only wind tunnel experience was dealing with wind loads and flow on high rise buildings (example: 1,135ft high), where the wind speeds are in our area of concern, roughly 200+/-mph
Enough of that nonsense! and a little history (as I recollect it)

When the GT40 was first announced there was a lot of literature regarding aerdynamics since Ford had done a little work with the Lola GT coupe that had wind uplift problems at the vehicle's rear at 130mph, and Ford was expecting to go against the Ferraris that didn't have this problem at 180mph
Ford's initial model research indicated that the GT40 would become airborn at about 230mph so they thought that they had the problem licked

On the track however, things didn't match since the rear weight bias transfered the lift to the front, and they tried a lot of variations
The nose was kept at a half to 1 inch lower than the rear and the nose itself went through a lot of variations
One problem with the nose was the 2 nostrils required to get airflow around the spare, unrecognized at that time was that the air was flowing around the cockpit rather than optimally over the top
The single nostril allowed air to flow up and over rather than around and allowed this down force to augment the nostril downforce and apply more force at the windshield, closer to the vehicle cg
Later a center divider was added in the wider single nostril to better guide the air over the roof
When you look at the Mk IV, you will notice the raised side fences after the nostril to again force the air over the windshield

The rear had the "duck tail" to add some downforce which basically was adequate at high speeds, a rear adjustable spoiler was added but used mainly for short tracks and rised the duck tail by about 3/4inch, full extension of the adjustment wasn't required

The small wings ahead of the front wheels were tried but usually abandoned since their effect was nil in comparison to the nostril modifications

The Lola GT had used openings in the rear glazing to relieve underbody air pressure but on the GT40, this negated the cool air entry from the after door scoops that captured cool air, not rather warm engine compartment air
The tail's openings alongside the central exhaust exit were used to relieve pressure build up and enlarged on the Mk II which had a slightly greater speed and engine heat from 100hp additional

The GT40 MkI body is pretty good aerdynamically and a wide single nostril with central divider and adjustable rear spoiler, and keeping the front slightly lower than the rear, should do the trick
A wing would produce more than adequate required downforce and a lot of drag, it shouldn't be required
The rear diffusers exhausting through the opening alongside the exhaust opening would be an interesting experiment if downforce on the places where you're accelerating at the max is causing wheelspin, might more easily be solved with a wideer tire tread

All of the above is personal conjecture and recollection and I hope that our group will tear it apart
Whatever you do, keep records of what you find and post them here
I hope that this doesn't bore everybody to death and hope that it might provide some help in your efforts

Best regards
Dennis

[Chris P.]

I was fascinated by the front suspension setup : the height-adjustment rod fitted to a rocker arm, the other end of which holds the bottom of the coil-over assembly. I assume that there is an advantage with this setup, as opposed to just winding the spring base up & down on the damper.

Any light that you can shed on this innovation would be greatly appreciated (but I understand if it falls under the veil of "secret racing men's business") !!

This is something I thought of doing years ago myself, mostly to get a higher wheel rate for a given spring rate, and also increase shock speeds. For a given amount of wheel movement, you will see more spring/damper movement with this setup than without. Higher shock speeds (over the standard mounting method that is) are typically better if you want the resolution for damping adjustment. Also, I know for a fact that the Stohr has had this on their DSR and CSR cars that have been winning the Runoffs here in the USA. It's kind of like using an inboard coilover operated by a pushrod. You get more design room through the fact that you have a belcrank where the motion ratio can be changed.