New car, the Phoenix replacement

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jeffw
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Name: Jeff Wiltshire

Re: New car, the Phoenix replacement

Postby jeffw » Mon Mar 25, 2019 4:23 pm

pigeondave wrote:
Has that gearbox got an oil cooler on it ? I see a weigh reduction coming :lol:


The Gearbox casing actual acts as the Dry sump tank for the engine.

The new slicks from Pirelli are putting an increase load on the suspension components. The rear wing produces 750Kg of downforce at 150MPH and I was seeing something between 170 & 180MPH heading to Avon Rise. Three cars had failures in the same place, Gould GR55 lost a suspension pivot (rear near side like mine) and the Pilbeam MP88 V10 lost its wing, all at similar speeds. Thankfully all the drivers and cars survived to tell the tale.

jeffw
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Re: New car, the Phoenix replacement

Postby jeffw » Mon Mar 25, 2019 4:30 pm

Looking good
Image
Going pretty quick, splitter on the floor and the wing is bending
Image
Post pushrod failure
Image
New new tyre required
Image

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pigeondave
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Re: New car, the Phoenix replacement

Postby pigeondave » Mon Mar 25, 2019 4:39 pm

jeffw wrote:
pigeondave wrote:
Has that gearbox got an oil cooler on it ? I see a weigh reduction coming :lol:


The Gearbox casing actual acts as the Dry sump tank for the engine.

The new slicks from Pirelli are putting an increase load on the suspension components. The rear wing produces 750Kg of downforce at 150MPH and I was seeing something between 170 & 180MPH heading to Avon Rise. Three cars had failures in the same place, Gould GR55 lost a suspension pivot (rear near side like mine) and the Pilbeam MP88 V10 lost its wing, all at similar speeds. Thankfully all the drivers and cars survived to tell the tale.


So you ran out of travel on the rear suspension and the thing buckled?
What does the data logger say for suspension movement at 175mph. Are you on the bumpstops?

jeffw
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Re: New car, the Phoenix replacement

Postby jeffw » Mon Mar 25, 2019 4:55 pm

Pretty much on the bumpstops at rest, that is how this aero cars run.

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pigeondave
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Re: New car, the Phoenix replacement

Postby pigeondave » Tue Mar 26, 2019 2:14 pm

Just looked at the photos on the computer (not the phone)

Looks like at speed you're bottoming out the suspension as the splitter is on the ground as you say.

let us know how you overcome the issues, be nice to know the development of the car (its the geek in me).

Im guessing stiffer springs or a revised bell crank rate. All exciting stuff.

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peter030371
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Re: New car, the Phoenix replacement

Postby peter030371 » Tue Mar 26, 2019 3:12 pm

From listening to the experts talking in the paddock on Saturday (and a bit of googling since getting home) its sounds like a proper aero car cannot use springs to control the suspension like we know it in our normal road cars (or even our JPSC cars).

If you think about it Jeffs car, with him, weighs a little over 600kg. At speed the rear wing is producing 750kg'ish of downforce (no idea what the rest of the car produces and without a moving ground plane full size wind tunnel we will never know) which is more than the weight of the car. So if you 'spring' the car for the static load it will compress a huge amount on any springs when moving. Apparently the way it is dealt with on aero cars is you effectively 'ride' on the bump stops and you fine tune the suspension setting at high speed with different bump stops. You also then throw into the equation rocker ratios and rising rate suspension but my mind started to fog over at that point :lol: In essence the springs don't do a lot other than hold the car up in the paddock!

It maybe that the bump stops Jeff is running are now not suitable for the increased speeds (or may have just aged over the years) but ultimately the pushrod was simple not up to the load it is now expected to take. So new, stronger, pushrods will be made and fitted :D

Of course all the above may be complete rubbish but that's how I understood it :geek:
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pigeondave
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Re: New car, the Phoenix replacement

Postby pigeondave » Tue Mar 26, 2019 3:53 pm

Yep, aero cars are a different beast, hence all the questions.

I too have been googling to see how things work.

Never knew that they effectively ride on the bump stops, must be like driving round with no suspension at speed. Hence the need for billiard table smooth tracks.

If you hit a bump and you're running an effectively bottomed out suspension system, somethings got to give.
If it doesn't I suppose you're pitched up into the air.

Dunno which I'd prefer. Something collapsing, or landing at 170mph+ :lol:

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peter030371
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Re: New car, the Phoenix replacement

Postby peter030371 » Tue Mar 26, 2019 4:04 pm

This is a similar thing happening at the same place for Heather Calder later on the same day https://youtu.be/fiSDYLfdAXk (except her rocker arm broke up rather than a pushrod failure)

Unfortunately I don't think anyone recorded Jeffs collapse but then his was not quite a spectacular just a bit smokey from the tyre lock up that followed
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pigeondave
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Re: New car, the Phoenix replacement

Postby pigeondave » Tue Mar 26, 2019 4:36 pm

peter030371 wrote:
his was not quite a spectacular just a bit smokey from the tyre lock up that followed


I'm sure it felt spectacular enough from the drivers seat :lol:

jeffw
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Re: New car, the Phoenix replacement

Postby jeffw » Tue Mar 26, 2019 4:58 pm

To be honest is was pretty benign, especially compared with the Pilbeam MP88 V10 which lost its rear wing in the same place, seemed to spin for ever

https://www.youtube.com/watch?v=Kn-a4psQ3uw

Off to get the suspension tweaked this weekend with variable rate bump stops and potentially stiffer/longer springs as well as stronger pushrods. Then we will see what we can do at Anglesey on the 6/7 and Croft towards the end of April.

The new Pirelli tyres are simple stunning, way more cornering capability than the Avon's I had on there.


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