Jump to content


Photo
- - - - -

Formula Cheap


  • Please log in to reply
76 replies to this topic

#1 chipmcdonald

chipmcdonald
  • Member

  • 1,824 posts
  • Joined: November 06

Posted 04 July 2014 - 23:54

Provided you were given an FIA-approved survival cell, who here could design a car to meet the following requirements:

 

~200 mph top speed

~5G cornering

~F1 acceleration/braking

~ Typical F1 race distance

 

 

The goal being, who could do it the *cheapest*......?  How cheap...?  Could you do it with a Chevy 350 box motor?  Off the shelf electric motors/batteries? 

 

 

 

 

 

 

 

 

 

 

 

 

 



Advertisement

#2 Ross Stonefeld

Ross Stonefeld
  • Member

  • 70,106 posts
  • Joined: August 99

Posted 05 July 2014 - 00:13

Depends.

 

Do I need to race it against other cars and be competitive? Add a zero to the budget prospectus. 



#3 chipmcdonald

chipmcdonald
  • Member

  • 1,824 posts
  • Joined: November 06

Posted 05 July 2014 - 00:35

Say a one off race.  Competitive?  You're in Formula Cheap, what is the budget cap?  The point being, how cheap can one get away with making some semblance of an open wheel pseudo-F1 car?



#4 Nemo1965

Nemo1965
  • Member

  • 7,836 posts
  • Joined: October 12

Posted 05 July 2014 - 07:41

That's an interesting topic. I think I once started a thread about it. Perhaps you should e-mail it as a challenge to Top Gear. They have the budget to do something like that!



#5 gruntguru

gruntguru
  • Member

  • 7,635 posts
  • Joined: January 09

Posted 05 July 2014 - 08:08

Provided you were given an FIA-approved survival cell, who here could design a car to meet the following requirements:

 

~200 mph top speed

~5G cornering

~F1 acceleration/braking

~ Typical F1 race distance

 

 

The goal being, who could do it the *cheapest*......?  How cheap...?  Could you do it with a Chevy 350 box motor?  Off the shelf electric motors/batteries? 

 

 

Say a one off race.  Competitive?  You're in Formula Cheap, what is the budget cap?  The point being, how cheap can one get away with making some semblance of an open wheel pseudo-F1 car?

Your first post didn't mention open-wheel. If open wheel wasn't mandatory, my design certainly wouldn't be. Open-wheel would drastically reduce the skirted area of my fan car.



#6 Ross Stonefeld

Ross Stonefeld
  • Member

  • 70,106 posts
  • Joined: August 99

Posted 05 July 2014 - 10:57

I think it's Magoo that has a great story about the world's fastest and cheapest Indycar that was used in a commercial for one of Juan Montoya's personal sponsors back in the 90s.



#7 Pat Clarke

Pat Clarke
  • Member

  • 3,023 posts
  • Joined: September 04

Posted 05 July 2014 - 14:10

Cheap, Fast, Reliable...chose any two. So sayeth  my old mate Carroll Smith.

 

Pat



#8 desmo

desmo
  • Tech Forum Host

  • 29,343 posts
  • Joined: January 00

Posted 05 July 2014 - 18:20

Your first post didn't mention open-wheel. If open wheel wasn't mandatory, my design certainly wouldn't be. Open-wheel would drastically reduce the skirted area of my fan car.

Yeah, once the stupid rules start--like mandating open wheels--the project is doomed.



#9 Greg Locock

Greg Locock
  • Member

  • 6,349 posts
  • Joined: March 03

Posted 06 July 2014 - 04:27

what power is a chev 350? 5g is very aggressive



#10 Kelpiecross

Kelpiecross
  • Member

  • 1,730 posts
  • Joined: October 10

Posted 06 July 2014 - 04:50


Certainly a very interesting question. I think it all depends on what "cheap" is - "cheap" by an average person's (or my own) standard - a few thousand up to $10,000 - or "cheap" by F1 standards - maybe up to $100,000. The original suggestion of a 350 Chev would imply a fairly low budget.
On the $100,000 budget - secondhand Al-block 7 litre Chev engine, Secondhand Albins V8 Supercar transaxle etc. Chassis - simple spaceframe or simple monocoque (no carbon fibre etc.) - suspension parts from road cars. Wheels/tyres as wide as possible (again used) - down force (to get the 5 gs) by big wings front and rear.
Overall size of the car - as small as possible - like F3/FFord size).
Any thoughts of full bodies and fan cars - maybe good but hard to fit into budget (possibly a part-body at the front for the car to "hide" behind).

I don't think a 350 Chev would do the job unless it was a $50,000 or $60,000 350.

#11 Lee Nicolle

Lee Nicolle
  • Member

  • 11,036 posts
  • Joined: July 08

Posted 06 July 2014 - 08:29

5G is a very good chassis, and the weight of a SBC would effect that. 200mph on a long circuit is fairly easy. A healthy 350 should deliver that, the later alloy engine would too. But probably cost more.  Engine cost does tend to be dictated by race length.

Realistically a production based engine will be a but borderline, though a LS type Chev, SBC, Ford, Mopar and possibly the Benz engine too would be viable. The SBC probably the cheapest and best bet though.

Though keep them simple, looking at Speedcafe this week a comparison between a 625hp Supercar engine and a 875hp 410 Sprintcar engine. The Supercar unit is twice as dear, 250 hp less and turns 1200rpm less. I would hope the Supercar engine does more race km though these days about a 1000km is all a 'Sprint' engine gets. A bit more [I hope] for an endurance engine. I know some teams [being a little gentle] are getting a season out of a 410 though the maintenance can be tedious.

I suspect a range of engines like I described would have more spectator appeal than the current stupidly expensive hybrid gunkers. And a simple transaxle would cost millions less. And the show would be the same. 



#12 gruntguru

gruntguru
  • Member

  • 7,635 posts
  • Joined: January 09

Posted 06 July 2014 - 11:00

Any thoughts of full bodies and fan cars - maybe good but hard to fit into budget (possibly a part-body at the front for the car to "hide" behind).
 

If 5G is a requirement, a full body fan car is a far cheaper option. If 200mph is also essential the full body fan car is a FAR, FAR cheaper option.



#13 Kelpiecross

Kelpiecross
  • Member

  • 1,730 posts
  • Joined: October 10

Posted 06 July 2014 - 11:20


It all depends on what the allowed budget is - maybe Mr. McDonald should specify an amount for the budget - it is his question after all. Without a target budget the question reduces to a "Formula Libre" one. The "full body fan car" probably would be best.

#14 Greg Locock

Greg Locock
  • Member

  • 6,349 posts
  • Joined: March 03

Posted 06 July 2014 - 11:39

I get, with 400 hp, 5g cornering at 200 kph, 320 kph top speed, is only achievable even with the aero of a fully enclosed body if the vehicle weighs less than 270 kg, and has tires with mu of 1.5, roughly F1 tires.. peak cornering would be at 260 kph, 7g.

 

So a fan car might do it with a more reasonable weight, or else you will be looking for tire sponsors. 

 

with more sensible tires mu=1.1, and a /peak/ latacc of 5g at 270 kph, the allowable weight increases to 320 kg, including driver, seat, tires, fuel, helmet and steering wheel.

 

If you insist on open wheeler then the first car would have an allowable weight of 180kg, and the second, 210 kg.

 

So the answer depends a fair bit on exactly at what speed you want your 5g-it obviously starts at tire mu at low speed, and then rises to a maximum before the engine power is insufficient to maintain speed at that lattacc. 

 

I'd add that having done the concept calculations for a fan car, you might be surprised by the power required, unless you can fit a decent sized fan.



#15 MatsNorway

MatsNorway
  • Member

  • 2,822 posts
  • Joined: December 09

Posted 06 July 2014 - 14:45

The closest in numbers today is turboed bikes usually at 500 or less hp. Add downforce bits and extra wheels and you realise the challenge.

 

What kind of numbers with a 4-500kg car? Given that the drivers weight is constant it sounds more doable with a bigger vehicle. Lower percentage of dead weight.


Edited by MatsNorway, 06 July 2014 - 15:08.


#16 Lee Nicolle

Lee Nicolle
  • Member

  • 11,036 posts
  • Joined: July 08

Posted 08 July 2014 - 10:19

The closest in numbers today is turboed bikes usually at 500 or less hp. Add downforce bits and extra wheels and you realise the challenge.

 

What kind of numbers with a 4-500kg car? Given that the drivers weight is constant it sounds more doable with a bigger vehicle. Lower percentage of dead weight.

Turboed bikes at 500hp. Drag race engines on nitro maybe. And they need a rebuild every 1/2 a mile or so of racing. Big bike engines do an ok job in small openwheelers but do not ever get near 200mph. Tracks with long straights kill them. And those small cars would be downright dangerous at those speeds.

The West style Sports Cars are a point of record. good on short tracks, lousy on long.

Too get the fairly big HP to drag the downforce and top speed you need a fairly large and powerfull engine. Or spend a whole lot more on a smaller engine. F1 engines do spring too mind!! And not this years turbo hybrid versions which are slower anyway. The old V8s or V10s spring too mind. That cost less than the current engines but still cost  a small countries GDP!!



#17 MatsNorway

MatsNorway
  • Member

  • 2,822 posts
  • Joined: December 09

Posted 08 July 2014 - 14:08

It had to be you Lee. You need some decent power to lift the wheel in 300+ Although the drag alone aids in lifting it i suspect. I can`t really prove to you that he has the claimed 499hp but it does move allright and goes for long runs.

 

This is ofc not a cheap thing to make reliable but it is the highest hp/weight powerplant readily available.

 

http://thekneeslider...power-hayabusa/

http://www.bigccraci...em.asp?item=101

 

But if you ask me this: do you really think you can make something faster than an F1 car cheaply? My answer is simply; No not at all.


Edited by MatsNorway, 08 July 2014 - 14:42.


#18 Ross Stonefeld

Ross Stonefeld
  • Member

  • 70,106 posts
  • Joined: August 99

Posted 09 July 2014 - 00:34

 

But if you ask me this: do you really think you can make something faster than an F1 car cheaply? My answer is simply; No not at all.

 

It depends what we consider cheap. Because if you don't have to follow the F1 rulebook, it's very easy to go fast.



#19 Lee Nicolle

Lee Nicolle
  • Member

  • 11,036 posts
  • Joined: July 08

Posted 09 July 2014 - 03:39

It had to be you Lee. You need some decent power to lift the wheel in 300+ Although the drag alone aids in lifting it i suspect. I can`t really prove to you that he has the claimed 499hp but it does move allright and goes for long runs.

 

This is ofc not a cheap thing to make reliable but it is the highest hp/weight powerplant readily available.

 

http://thekneeslider...power-hayabusa/

http://www.bigccraci...em.asp?item=101

 

But if you ask me this: do you really think you can make something faster than an F1 car cheaply? My answer is simply; No not at all.

I love all the turbo heads that claim unheard of power. A few even do go racing where their 700hp 2 litres claim seem to have most on strike! And recently I saw one passed in a straight line by a carburettored 2 litre with 220hp! 

Though 500hp on a dyno may be achievable it will have no driveability and the engine will not last very long.

Go look at the Dyno shootouts where engine builders build massive HP engines that would be useless in the real world.



Advertisement

#20 Greg Locock

Greg Locock
  • Member

  • 6,349 posts
  • Joined: March 03

Posted 09 July 2014 - 04:45

" Because if you don't have to follow the F1 rulebook, it's very easy to go fast."

 

yes, but not 5g and 200 mph at the same time. In fact I don't think 5g cornering is ever going to be cheap.



#21 gruntguru

gruntguru
  • Member

  • 7,635 posts
  • Joined: January 09

Posted 09 July 2014 - 09:21

If you use the 5G cornering as the starting point, I think the 200mph top speed is probably easier than the "F1 acceleration and braking" specified in the OP.

- Enclosed wheels and fully skirted perimeter means the 5G can be achieved without a fan.

- Unsprung skirts, wings and underbody to maintain peak aero performance under extreme chassis loads and enable the use of  . . .

- Sensible spring rates for maximum mechanical grip.

 

500 hp should be enough to see the 200 mph but a heavier engine like the 350 SBC won't match the F1 acceleration (700 hp, 500 kg). Perhaps an LS-9 with some extra boost? Heavy engine at about 250kg but 800+ reliable horsepower on race fuel would be cheap and easy. High CG is an issue with stock block V8's and any street engine design including motorcycle will need some serious lubrication mods to handle 5G lateral.



#22 Ross Stonefeld

Ross Stonefeld
  • Member

  • 70,106 posts
  • Joined: August 99

Posted 09 July 2014 - 11:11

" Because if you don't have to follow the F1 rulebook, it's very easy to go fast."

 

yes, but not 5g and 200 mph at the same time. In fact I don't think 5g cornering is ever going to be cheap.

 

I thought it 200mph top speed and 5g cornering, not together?



#23 desmo

desmo
  • Tech Forum Host

  • 29,343 posts
  • Joined: January 00

Posted 09 July 2014 - 14:16

 

 

I'd add that having done the concept calculations for a fan car, you might be surprised by the power required, unless you can fit a decent sized fan.

 

Didn't Jim Hall's fan car use two snowmobile engines to power the fans? Maybe one? I could be remembering wrong, it was obviously a long time ago.  Let's assume two @ 50bhp per, would 100bhp be far off your calcs?



#24 Greg Locock

Greg Locock
  • Member

  • 6,349 posts
  • Joined: March 03

Posted 09 July 2014 - 23:30

I'll dig around, may still have the original calculations, but that sounds about right. The power consumption is obviously a function of three things - the leakage rate, the desired pressure differential, and the fan efficiency. If you are using the main engine to power the fans then obviously under braking there is no issue, but at high speed high g you need a lot of engine power to get the car round the corner.



#25 desmo

desmo
  • Tech Forum Host

  • 29,343 posts
  • Joined: January 00

Posted 10 July 2014 - 04:27

I wonder how many hp conventional F1 wings eat in drag penalty at speed? Obviously it would depend on velocity, aero package and probably a dozen other variables, but I'd be surprised if it were often less than that 100bhp.  With fans powered independently, one could obviously easily control the amount of df as wanted by simply throttling the fan engine(s), off for the straights and on appropriate amounts for each individual corner and braking/accel zone. 



#26 Greg Locock

Greg Locock
  • Member

  • 6,349 posts
  • Joined: March 03

Posted 10 July 2014 - 05:45

Agreed. I think I can work it out with numbers I have.

 

Ross -sorry I meant 200 mph, and 5g, in one car, not simultaneously. The 200mph in a straight line is not especially tricky as a single target in a streamliner with 350 hp, but 5g is never going to be cheap. 



#27 gruntguru

gruntguru
  • Member

  • 7,635 posts
  • Joined: January 09

Posted 10 July 2014 - 08:11

I wonder how many hp conventional F1 wings eat in drag penalty at speed? Obviously it would depend on velocity, aero package and probably a dozen other variables, but I'd be surprised if it were often less than that 100bhp.  With fans powered independently, one could obviously easily control the amount of df as wanted by simply throttling the fan engine(s), off for the straights and on appropriate amounts for each individual corner and braking/accel zone. 

Of course without the F1 rules banning movable aero, it is also easy to vary the lift and drag of any winged setup.

 

From a drag POV 100 hp = about 85 kg @ 200mph. Assuming our race car weighs 500 kg, we need at least 1167 kg of DF for 5g latacc. (mu = 1.5). So a passive aero system producing 85kg drag would need an L/D of 1167/85 = 13.7


Edited by gruntguru, 10 July 2014 - 08:23.


#28 Ross Stonefeld

Ross Stonefeld
  • Member

  • 70,106 posts
  • Joined: August 99

Posted 10 July 2014 - 10:56

Agreed. I think I can work it out with numbers I have.

 

Ross -sorry I meant 200 mph, and 5g, in one car, not simultaneously. The 200mph in a straight line is not especially tricky as a single target in a streamliner with 350 hp, but 5g is never going to be cheap. 

 

I'd think Tires&Tunnels would be a big help. Can we cheat and use an oval with a lot of banking :lol:

 

It also depends on how we consider cost. You could take an old Indycar and tart it up and go scary-quick. But there was obvious historic sunk costs in bringing that car to reality the first time around.



#29 Greg Locock

Greg Locock
  • Member

  • 6,349 posts
  • Joined: March 03

Posted 10 July 2014 - 12:41

Ross , yes banked tracks make it possible, but that spoils the fun.

 

gg -13.7 is way beyond any car in Katz. a pure tunnel, no wings is 10, and that runs out of puff way short of 3g for real cars, and doesn't include skin friction. In reality 7 is the absolute optimum for L/D, and that drops rapidly as CL increases.

 

The incremental CL/CD for open wheeler wings is about 1.5.  Ouch. 


Edited by Greg Locock, 10 July 2014 - 12:41.


#30 Nemo1965

Nemo1965
  • Member

  • 7,836 posts
  • Joined: October 12

Posted 10 July 2014 - 17:44

I know the topic includes 5 g cornering and in thus, we the posters 'have' to follow the topic... but... why?

 

If I think of a total reset of open wheel racing (including F1), and I would have the power (woeha-hahahhahah!) I would prohibit using wings. Sigar and drop-shaped cars would get fantastic straight line speed, would have spectacular behaviour and challenge drivers to the extreme.

 

For example, I have sometimes have daydreams that the current F1 field would do one race in the car portrayed here:

 

http://blog.hemmings...on-of-the-cost/

 

I don't know if the company still exists, and if the cars are really for sale (or were ever), but we are talking about 72.000 euro's for a spectacular car...



#31 gruntguru

gruntguru
  • Member

  • 7,635 posts
  • Joined: January 09

Posted 10 July 2014 - 21:56

Ross , yes banked tracks make it possible, but that spoils the fun.

 

gg -13.7 is way beyond any car in Katz. a pure tunnel, no wings is 10, and that runs out of puff way short of 3g for real cars, and doesn't include skin friction. In reality 7 is the absolute optimum for L/D, and that drops rapidly as CL increases.

Yep, so a 500kg car with passive aero, L/D = 7, mu = 1.5, Latacc = 5 will need 200 hp to push the "DF system" at 200 mph.

 

For a fully enclosed car with unsprung bodywork perhaps the "DF system" is the entire bodywork so the total drag at 200 mph is 170kg/200hp? 



#32 Greg Locock

Greg Locock
  • Member

  • 6,349 posts
  • Joined: March 03

Posted 11 July 2014 - 01:25

Not too sure how you worked that out. My spreadsheet is on another PC, I may grab a copy on sunday



#33 Lee Nicolle

Lee Nicolle
  • Member

  • 11,036 posts
  • Joined: July 08

Posted 11 July 2014 - 06:01

Agreed. I think I can work it out with numbers I have.

 

Ross -sorry I meant 200 mph, and 5g, in one car, not simultaneously. The 200mph in a straight line is not especially tricky as a single target in a streamliner with 350 hp, but 5g is never going to be cheap. 

Especially with a heavy cheap engines such as a Chev or similar.

Though for a cheap formula really who needs 5G, or even 200mph. A modern version of F5000 using modern style carbon chassis, stockblock engines up to 6litre [or 6.3 maybe] and generic commercially available transaxles [Hewland or whatever. Plenty available] would be just as good a racing. Or even stockblock V6s up too 3500 though they usually sound shitfull! Limit aero, flat bottom with mininum ride height. = Good racing, cars that move about more and cheap [in comparison] racing though the maintenance time will be higher as those engines will require more maintenance. Though with say 600-650hp engines they will last a lot longer than 7 or 800hp engines.



#34 gruntguru

gruntguru
  • Member

  • 7,635 posts
  • Joined: January 09

Posted 11 July 2014 - 07:09

Not too sure how you worked that out. My spreadsheet is on another PC, I may grab a copy on sunday

500 kg car. 5g latacc

Fy = 5 x 500 = 2500 kg.

Fz = Fy/mu = 2500/1.5 = 1666 kg

DF = Fz - m = 1666 - 500 = 1166 kg

L/D = 7

D = L/7 = 1166/7 = 167 kg

Power = D x v = (167 x 9.8) x (200 x 0.447) = 146 kW = 200 hp



#35 gruntguru

gruntguru
  • Member

  • 7,635 posts
  • Joined: January 09

Posted 11 July 2014 - 07:13

Especially with a heavy cheap engines such as a Chev or similar.

Though for a cheap formula really who needs 5G, or even 200mph. A modern version of F5000 using modern style carbon chassis, stockblock engines up to 6litre [or 6.3 maybe] and generic commercially available transaxles [Hewland or whatever. Plenty available] would be just as good a racing. Or even stockblock V6s up too 3500 though they usually sound shitfull! Limit aero, flat bottom with mininum ride height. = Good racing, cars that move about more and cheap [in comparison] racing though the maintenance time will be higher as those engines will require more maintenance. Though with say 600-650hp engines they will last a lot longer than 7 or 800hp engines.

The thread is about matching F1 performance on the cheap, not a cheap, alternate formula.


Edited by gruntguru, 11 July 2014 - 22:09.


#36 Greg Locock

Greg Locock
  • Member

  • 6,349 posts
  • Joined: March 03

Posted 11 July 2014 - 07:44

OK, yes, seemed very low but i forgot you were using L/D=7, which implies a very efficient ground effect car.



#37 Lee Nicolle

Lee Nicolle
  • Member

  • 11,036 posts
  • Joined: July 08

Posted 12 July 2014 - 00:38

The thread is about matching F1 performance on the cheap, not a cheap, alternate formula.

You will not. Pure and simple. Weight is everything. The power is readily achievable. The speed is quite easy, the cornering will never be, nor braking unless you go to far bigger brakes. And bigger wheels to enclose them.

F1 is stupidly expensive, an the hybrids plain moronic. And have no crown appeal. The very fancy transaxles used would never adapt yet alone handle the torque and weight of any stock block. turbo4 V6 or V8. 

So you are left with a c/f tub! Which to be fair would probably be incompatible with all the 'cheap' mechanicals.

Though in the day F5000 was faster than F1 on more open circuits, possible as would what I described. BUT a different class of car and different dynamics. Slower on corners and braking, possibly faster in a straight line which still can equal similar lap times.



#38 Kelpiecross

Kelpiecross
  • Member

  • 1,730 posts
  • Joined: October 10

Posted 12 July 2014 - 04:55


Without attempting any clever calculations (probably couldn't anyhow)but by using a bit of logic - a MotoGP bike has roughly the same straight line performance as an F1 car (the 'bike in fact may be slightly better). The 'bike weighs around 160Kg and has a bit under 300HP. I would have thought that it should be possible to build a full-bodied slightly oversized go-kart style car with about the same drag coefficient as a MotoGP 'bike weighing about the same and with an equal (or greater) amount of power. As for cornering g's - presumably a go-kart and a F1 car without any form of down force probably have about the same maximum cornering g. As this is a "anything goes" formula - the car (kart) could have variable angle wings etc. and even some form of underbody downforce.
As LN points out there is no shortage of very light cars with 'bike engines and they all run out of puff at about 160mph - but it should be possible - and it would certainly be a lot cheaper than F1.

#39 gruntguru

gruntguru
  • Member

  • 7,635 posts
  • Joined: January 09

Posted 12 July 2014 - 06:34

You will not. Pure and simple. Weight is everything. The power is readily achievable. The speed is quite easy, the cornering will never be, nor braking unless you go to far bigger brakes. And bigger wheels to enclose them.

Have to disagree. The OP's concept is - throw away the rule book, how much does it cost to build a no-rules car to match F1 acceleration, braking, cornering and top speed. F1 performance could be matched at a fraction of the price - at a guess, less than a fifth of the cheapest F1 in the field. (big guess here - thinking perhaps the cheapest F1 might cost $5M per car???)

 

The current F1 rules are massively restrictive. Each of the rules in the list below (not exhaustive - just a few that come to mind) places a huge limitation on performance.

- Open wheel body style

- No venturi underbody

- No skirts

- No active aero

- No unsprung aero

- Power limited by airflow or fuel flow limits

- Spec tyres



Advertisement

#40 gruntguru

gruntguru
  • Member

  • 7,635 posts
  • Joined: January 09

Posted 12 July 2014 - 06:38

And have no crown appeal.

Assume you meant "no crowd appeal".

 

I wonder what it is then, that attracts the massive crowds, TV audiences, Forum Posters etc??



#41 MatsNorway

MatsNorway
  • Member

  • 2,822 posts
  • Joined: December 09

Posted 12 July 2014 - 22:50

Give us a sum up. Grunt. Will it possibly be doable with a 400kg car with 500hp? because those numbers is easily doable. Lets say our basis is a 500-600hp bikeish engine at 1.5L how low must we go in weight with a fair L/D ratio?



#42 gruntguru

gruntguru
  • Member

  • 7,635 posts
  • Joined: January 09

Posted 13 July 2014 - 01:07

If you could build a 400kg car with 500 hp, enclosed bodywork, plan area 150% of an F1, frontal area similar to F1, CGH similar to F1 - it could meet the OP's criterion. It would use unsprung venturi underbody and skirts. L/D about 5 would easily produce the required DF while still permitting 200mph top speed.

 

Not sure on the transmission. 500hp is probably a bit much for the bike trans given that the car will have a lot more traction than any bike.



#43 Greg Locock

Greg Locock
  • Member

  • 6,349 posts
  • Joined: March 03

Posted 14 July 2014 - 06:08

I wonder how many hp conventional F1 wings eat in drag penalty at speed? Obviously it would depend on velocity, aero package and probably a dozen other variables, but I'd be surprised if it were often less than that 100bhp.  With fans powered independently, one could obviously easily control the amount of df as wanted by simply throttling the fan engine(s), off for the straights and on appropriate amounts for each individual corner and braking/accel zone. 

 

 

Here's the drag breakdown for an f1 car. A=1.25

 

                           cd      cl         hp at 320 kph     

Base shape         0.3     0        216

ground effect      0.2     2        144

wings                  0.4     0.8     287

 

total                   0.9     2.8      646

 

So the wings  provide around half the downforce for twice the power consumption of the body in ground effect


Edited by Greg Locock, 14 July 2014 - 06:17.


#44 gruntguru

gruntguru
  • Member

  • 7,635 posts
  • Joined: January 09

Posted 14 July 2014 - 08:40

Those numbers are all obviously applied to the same 1.25 m2 (frontal?) area. It would be interesting to see a breakdown of areas and actual coefficients. e.g. there is no way a bare open-wheel F1 body has a cd of 0.3

 

Forces in kg (obtained by working backwards from power) are

 

                           cd      cl      hp@320    Drag       Lift

Base shape        0.3     0        216          185           0

ground effect      0.2     2        144           124     1236

wings                  0.4     0.8     287           247       494

 

total                     0.9     2.8     646           556     1730

 



#45 MatsNorway

MatsNorway
  • Member

  • 2,822 posts
  • Joined: December 09

Posted 14 July 2014 - 09:42

"lift" fixed.

Those numbers are all obviously applied to the same 1.25 m2 (frontal?) area. It would be interesting to see a breakdown of areas and actual coefficients. e.g. there is no way a bare open-wheel F1 body has a cd of 0.3

 

Forces in kg (obtained by working backwards from power) are

 

                           cd      cl      hp@320    Drag       Lift

Base shape        0.3     0        216          185           0

ground effect      0.2     2        144           124    -1236

wings                  0.4     0.8     287           247      -494

 

total                     0.9     2.8     646           556    -1730



#46 Greg Locock

Greg Locock
  • Member

  • 6,349 posts
  • Joined: March 03

Posted 14 July 2014 - 10:01

Haven't you come across that? wing people use chord, and work in lift per m (I guess) , aircraft people use plan area, auto use frontal area. The important numbers work out the same, just remember to compare like with like.



#47 MatsNorway

MatsNorway
  • Member

  • 2,822 posts
  • Joined: December 09

Posted 14 July 2014 - 10:19

Me? no. Never heard about chord in that relation. If they use lift like that i must assume it is shortened from lift potensial. otherwise it makes sense to use a negative prefix.

 

But a more fun topic is that a car like that could perhaps do at least 3G turns upside down? :)

 

And even more importantly. 400kg with a 650+hp engine does sound doable today. Hard yes, but doable by F1 people. But the safety tub will tip the weight over surely?

 

Edit: safety cell is as little as 35kg?

http://www.formula1-.../monocoque.html

 

In DTM its at minimum 25kg. So i call that confirmed.

http://www.dtm.com/e...afety-cell.html

 

So say a light driver at 60kg + gear 5kg + cell 35kg = 105kg total. 295kg for the rest.  fuel? 35L-40L?

 

Engine weight with everything = 80kg?


Edited by MatsNorway, 14 July 2014 - 10:33.


#48 Greg Locock

Greg Locock
  • Member

  • 6,349 posts
  • Joined: March 03

Posted 14 July 2014 - 10:42

safety cell 35

driver 60 (poor old webber)

helmet

clothes

seat

seatbelt

steering wheel and column and rack and tierods

engine

clutch&gearbox

diff

halfshafts

fuel

rads

oil cooler system

front and rear suspension arms,

springs shocks

body structure and covers

wings

wheels 16kg

tires 44 kg

brakes

uprights

elcetrics

electronics

braking

etc


Edited by Greg Locock, 14 July 2014 - 10:43.


#49 Greg Locock

Greg Locock
  • Member

  • 6,349 posts
  • Joined: March 03

Posted 14 July 2014 - 10:53

Just thinking about it, it is obvious that 'cheap' power and light weight are probably the cost effective solution, and I'd have thunk that Magoo or his more formal friend would be a great source for info - who would you go to for a crate engine pus upgrades to last say 15 weekends racing between rebuilds, and how many horses per pony do we get?

 

http://www.urbandict...e.php?term=Pony


Edited by Greg Locock, 14 July 2014 - 10:56.


#50 BS1

BS1
  • New Member

  • 5 posts
  • Joined: April 10

Posted 14 July 2014 - 14:18

Why not go,

Turbo SBC, 1500 hp. A transaxle that will hold.

A L/D of 2.7 should be reasonable/easy.

5.2 clA to keep it to a 200mph top speed.

Keep it under 800kg and with the right tires you should be able to go under 1.30 at Melbourne. In theory.

 

But this assumes that you are not using an active system and why wouldn't you? An active system could have ridiculous wings.