RE: McMurty Automotive targets Goodwood hill record

[ch37]

julian64 said:

what I want to see is someone prove that the car has more downforce than its weight.

Seeing a car drive upside straight for a short period would certainly prove it to doubters like me.

Till then I take comments liek this with a pinch of salt.

Why would they lie about it? The car isn't for sale and I'm sure the team they've assembled is pretty competent with the sort of software that is giving them these numbers.

They're doing the opposite of most new start car companies, the fact that so many didn't know about this despite it being around for a while now in running form kinda goes to show the engineering is coming before the marketing.

[Kawasicki]

samoht said:

Midgster said:

I'm sure he didn't mean it literally that he doesn't know how ground effects works, more to the point 2000kg of downforce at 0mph...so basically the fan itself is sucking the car down to the road with 2000kg of force......that's some fan!!!

A complete vacuum over a one metre square suction area would yield a downforce of 10 tonnes, so 2 tonnes 'only' requires lowering the pressure by 20% from normal.

Yep. Small pressure differences over large areas create large forces. I did a back of an envelope calc., and using a circular area, with a diameter of 0.6m, you would need 2/3 of a bar, or 10PSI vacuum to create a force equivalent to 2000kg.

Now to maintain that vacuum might be tricky.

[julian64]

ch37 said:

julian64 said:

what I want to see is someone prove that the car has more downforce than its weight.

Seeing a car drive upside straight for a short period would certainly prove it to doubters like me.

Till then I take comments liek this with a pinch of salt.

Why would they lie about it? The car isn't for sale and I'm sure the team they've assembled is pretty competent with the sort of software that is giving them these numbers.

They're doing the opposite of most new start car companies, the fact that so many didn't know about this despite it being around for a while now in running form kinda goes to show the engineering is coming before the marketing.

The car isn't for sale but they are making a public event so they are inviting publicity.

I'm a cynic, so secondly there is a very big difference between the software putting out the numbers and the car actually managing to produce them. For a very long time F1 has said their cars could do it but to my knowledge there are no videos.

I think the amount of publicity an F1 teams would get if they managed it would be well worth their attempt to achieve it. But no-one does. There might be many reason for that but as a cynic I keep coming back to the most obvious one.

[samoht]

julian64 said:

I'm a cynic, so secondly there is a very big difference between the software putting out the numbers and the car actually managing to produce them. For a very long time F1 has said their cars could do it but to my knowledge there are no videos.

I think the amount of publicity an F1 teams would get if they managed it would be well worth their attempt to achieve it. But no-one does. There might be many reason for that but as a cynic I keep coming back to the most obvious one.

F1 teams aren't a travelling funfair, they're sports teams competing to win a championship.

It's a fact that above a certain speed the cars' downforce exceeds their weight. Absolutely no reason to lie about it.

Therefore above that speed, an F1 car could *in theory* drive on an inverted track surface ('the ceiling'). However, think a minute about the other implications.

First you need a long enough stretch of 'ceiling', which has to be completely flat and smooth like a tarmac racetrack, for the car to drive on.
Then you need some kind of ramps to allow the car to transition from the ground to the ceiling and back again safely at high speed.
Now you need to consider that although the total contact force on the car will be positive above x mph, it will still be less than when running at that speed on the ground as the car's own weight acts against rather than for it. How does that affect high speed stability? How much does the higher ride height reduce the aero downforce? What's the front/rear balance?
Now consider that the engine is operating inverted, so all the oil, water, fuel etc will fall to the 'top' of their respective tanks / sumps / etc.

Now, all of these *could* be overcome, but it would take team engineers away from their purpose of making their car quicker around the actual tracks they race on.

Remember also that teams are limited in how much budget they can spend, hours of testing and CPU-minutes of simulation, so all of this would come out of a limited pot of effort.

So no, I think overcoming all the secondary challenges and setting up a suitable venue would in no way be 'well worth' taking so much of the team's effort away from winning a championship.

[Funk]

Matt Bird said:

Sorry for the spelling mistake, folks - amateur hour yesterday!

Should be McMurtry and not McMurty. Won't make that mistake again!

Thread title needs a tweak as well Matt...

[Olivera]

I'd be all for seeing a PHer demonstrate an extended loop-the-loop in a McMurtry at FoS 2023.

[julian64]

samoht said:

F1 teams aren't a travelling funfair, they're sports teams competing to win a championship.

literally took one google
https://www.youtube.com/watch?v=pOdpuIZ-Tyw


I can see how those stunts gave them a few extra seconds around imola.

[ch37]

julian64 said:

literally took one google
https://www.youtube.com/watch?v=pOdpuIZ-Tyw


I can see how those stunts gave them a few extra seconds around imola.

Old cars with very, very minimal modifications. Bit different to the engineering challenge of getting everything to work upside down and building a staggeringly large facility to do it in.

[CubanPete]

Olivera said:

Why does it have to look so rubbish? It's like they've saved a picture of the car but then changed aspect ratio.

It's primarily about minimising frontal area. Wind resistance being the biggest waste / consumer of energy. That is also why it has fan assisted downforce rather than the BGW you might strap on to your proton GTi.

Very special car here led by one of the UKs best ever engineers.

One to be proud of.

[julian64]

ch37 said:

julian64 said:

literally took one google
https://www.youtube.com/watch?v=pOdpuIZ-Tyw


I can see how those stunts gave them a few extra seconds around imola.

Old cars with very, very minimal modifications. Bit different to the engineering challenge of getting everything to work upside down and building a staggeringly large facility to do it in.

I think you are making excuses. I pretty much guarantee that a team has a wind tunnel capable of simulating track speeds.

So why not rope a stationary car to the roof, switch the fan on and then cut all the ropes apart from the one at he front.
Car stays on the roof, doesn't need the straps, job done!

The stunt wouldn't be as impressive but it would demonstrate what up till now we just have to accept as true cos the computer says yes.

Anyway enough of a thread hijack.

[Big Nanas]

Sandpit Steve said:

Good luck to them - but Goodwood, please let the 919 and modern F1 cars go up the hill against the clock too.

I'm sure you know, but the F1 cars were allowed to compete in the timed shootout...right up until Nick Heidfeld smashed the time in the McLaren F1MP4/13 back in 1999.

I still watch this run as it looked so raw and on the edge. It looks like he's on the absolute brink of a massive accident on the entire run. No wonder Goodwood decided for safety reasons they'd ban F1 cars from then!

Here's the video for everyone's enjoyment.

https://www.youtube.com/watch?v=qP6oJGiX-Ds
The VW ID-R that broke that record in 2019 looked serene in comparison.

https://www.youtube.com/watch?v=8il5ohB8FYk&t=...

I'll be at the FoS on Friday, so I'm looking forward to seeing the McMurtry do a few test runs up the hill for sure!

Edited by Big Nanas on Friday 17th June 18:36

[ch37]

Big Nanas said:

I'm sure you know, but the F1 cars were allowed to compete in the timed shootout...right up until Nick Heidfeld smashed the time in the McLaren F1MP4/13 back in 1999.

I still watch this run as it looked so raw and on the edge. It looks like he's on the absolute brink of a massive accident on the entire run. No wonder Goodwood decided for safety reasons they'd ban F1 cars

And I don't blame them, as somebody who stands behind two bails of hay watching every year. All for a bit of raw motorsport thrill but the place is packed with families etc, 5 or 6 deep in places. An arms race to smash records is ultimately going to end in disaster eventually. They have a pretty decent balance now I think, I'd take the access and views we get now with a slightly neutered run vs catch fencing and flat out 5 year old F1 cars.

I've seen people mentioning rallying or indeed circuit racing as justification for allowing balls to the wall timed runs. At a rally 99% of spectators are 100% alert to the dangers, at a circuit they have significantly more buffer between machine and spectator. At FoS a couple of hay bails stand between machine and a whole cross section of people, from those aware of escape routes to those quaffing champagne and not even looking at the hill (but stood right next to it).

[Philmoco]

I remember a McMurty running a Hillman Imp engined bike frame up the Esholt Sprint back in the 60s. It burned some asphalt!

[ch37]

41.29 today and it looked like they had a couple of seconds to find in it still, absolutely incredible.

I think Alex Summers is in the car tomorrow, will be interesting to see how he gets on with his second run. I would guess the car easily has the record within it.

[Big Nanas]

I saw this go up the hill on Friday, and it was breathtaking. Chatting to the guys on the McMurtry stand, he was telling me they were running at 80% power on Friday, steadily moving up as the weekend progresses.
Audible gasps from the people around me when it came past.

[Rozzers]

Is this of any use for anything other than hill climbs though?

I’m assuming that the battery is expended after a run like that, if so it might as well be a rocket.

[ch37]

A few shots from yesterday, properly breathtaking thing…

FoS 2022 by Chris Harrison, on Flickr

FoS 2022 by Chris Harrison, on Flickr

FoS 2022 by Chris Harrison, on Flickr

[Kawasicki]

That was great to watch. It properly hammered along. Well done to all involved, nice driving too.

[plfrench]

@Chris Harrison, that's some impressive photography there considering the speed that thing was hurtling along!!

[samoht]

+1 I think those are the absolute best pics I've seen anywhere of this thing, McMurtry's own included. Looks fab!

Rozzers said:

Is this of any use for anything other than hill climbs though?

I’m assuming that the battery is expended after a run like that, if so it might as well be a rocket.

1000hp (the power output) is ~750 kW.

750 kW for 40 seconds (if it was at full power all the way up) is just over 8 kW hrs, out of the 60 kWh battery.

Assuming average power up the driveway is half of peak, that would be around 4 kWh used per run, so could easily do a dozen runs between charges. I think the intensity and forces involved would probably warrant a tea break after twelve runs for the driver too!