Anyone notice the new Diesel Land Speed Record of 350 mph (563 kph) just set by a Andy Green from England? There's some amazing numbers, including 10.5:1 compression.
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World's Fastest Diesel 1
- Thread starter Fabrico
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TheBlacksmith
Mechanical
It also says "Twin compound turbochargers with twin compound intercoolers", so it sounds like they have an large amount of boost, making a relatively low compression ratio necessary.
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SomptingGuy
Automotive
Hmm, 5.2 Bar, that must give a prety high Pmax!
Pretty impressive, but keep in mind this is a "one off" situation with loads of R&D and advertising bucks in the budget..Also, life expectency is measurered seconds and not hours.................If you really want to see where #2 is going and where technology has taken diesel, look at the marine pleasure boat diesel market where you will find "in production" diesels pushing 80+ HP per liter and 3 bar (85++" HG, 40+++ PSI) turbo boost.....To me, that's trully impressive..............
Tony
Tony Athens
Tony
Tony Athens
crysta1c1ear
Automotive
400 MPH is about 180 m/s.
With a CdA of 0.15 m2 and assuming air density of 1.2 kg/m3, they will be effectively hitting about 0.18 kg of air for every metre travelled.
So every second the JCB hits 0.18*180 = 32.4 kg of air with a kinetic energy of 1/2*m*v*v of (1/2) * 32.4 * 180 * 180 = 524880 Joules.
That is 524 kW required to overcome air resistance.
They are using a 560 kW engine.
So what is holding the thing back from getting to 400 MPH?
With a CdA of 0.15 m2 and assuming air density of 1.2 kg/m3, they will be effectively hitting about 0.18 kg of air for every metre travelled.
So every second the JCB hits 0.18*180 = 32.4 kg of air with a kinetic energy of 1/2*m*v*v of (1/2) * 32.4 * 180 * 180 = 524880 Joules.
That is 524 kW required to overcome air resistance.
They are using a 560 kW engine.
So what is holding the thing back from getting to 400 MPH?
globi5
Mechanical
- Oct 10, 2005
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^ friction is not just caused by air (drivetrain, wheels).
Besides air density at this altitude is probably less than 1.08 kg/m^3 (since it is pretty hot up there it might even reach 1 kg/m^3) and RAM air is already significant at these speeds (over 10% intake pressure increase), so according to your calculation it should even be faster.
Besides air density at this altitude is probably less than 1.08 kg/m^3 (since it is pretty hot up there it might even reach 1 kg/m^3) and RAM air is already significant at these speeds (over 10% intake pressure increase), so according to your calculation it should even be faster.
SomptingGuy
Automotive
Nope. They used two of them!
The limiting factor is tyres. They were only rated to 350 mph. The car is faster than its tyres.
For those who want some insight into the engine, try this:
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- #15
Most of this vehicles don't use tires at all
just a strong steel wheels
the driver is Andi Green who drove the SSC breaking the sound speed few years ago , he is a pilot in UK army & was chosen for the better training in controlling vehicles with LIFT
. just a tenth of degree of nose going up could
be disaster.
just a strong steel wheels
the driver is Andi Green who drove the SSC breaking the sound speed few years ago , he is a pilot in UK army & was chosen for the better training in controlling vehicles with LIFT
. just a tenth of degree of nose going up could
be disaster.
SomptingGuy
Automotive
globi5,
You are right about the friction thing - it needs proper tyres. And even so there's apparently some kind of "wheel-spin-ometer" in the cab too to monitor what's going on.
w.r.t. all-wheel drive, it already is. One engine for the front; one for the back.
You are right about the friction thing - it needs proper tyres. And even so there's apparently some kind of "wheel-spin-ometer" in the cab too to monitor what's going on.
w.r.t. all-wheel drive, it already is. One engine for the front; one for the back.
SomptingGuy
Automotive
level,
SSC was an upside-down plane with forward force coming from those jet engines. Dieselmax needed force through it's wheels. Hence the requirement for good tyres.
SSC was an upside-down plane with forward force coming from those jet engines. Dieselmax needed force through it's wheels. Hence the requirement for good tyres.
patprimmer
New member
levil
Are you seriously suggesting that traction is irrelevant to drive line types where one transmits power through the wheels and one does not, or are you suggesting that there is no difference in the traction of rubber vs steel, or are you suggesting that on a traction limited performance, that traction can be further reduced.
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Are you seriously suggesting that traction is irrelevant to drive line types where one transmits power through the wheels and one does not, or are you suggesting that there is no difference in the traction of rubber vs steel, or are you suggesting that on a traction limited performance, that traction can be further reduced.
Regards
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Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
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