| [ Total Views: 589 | Total Replies: 9 | Thread Id: 48309 ] |
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 wombatone
A.k.a.: Michael
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| posted on January 24th, 2006 at 08:27 PM |
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Terminal velocity calculator
Has any one seen a program that can calculate the terminal velocity of a bug.
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hellbugged
A.k.a.: Daimo Pell
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| posted on January 24th, 2006 at 09:58 PM |
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ask dave- he knows things- aka "dangerous"
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crewcabconnection
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| posted on January 24th, 2006 at 10:07 PM |
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what altitude will you be dropping it from?
Loves a lolcat
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dangerous
A.k.a.: Dave Butler Muffin Man
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| posted on January 25th, 2006 at 06:31 PM |
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The only formula I have is for terminal velocity in the standing 1/4 mile.
You will need engine power and your vehicle mass in lbs.
Answer will be in MPH.
Get the cubed root of (HP divided by weight), and then multiply your answer by 234.
So if your Volksy has a 60hp engine and weighs 1870lbs (850kgs)
=cubed root of (60 divided by 1870)
=cubed root of .0321
=.318
Then multiply by 234=74mph.
This will be a rude shock to all those people who think their engines make more power.
If you have a chassis dyno figure then you can add between 10 and 15 percent (depending on calibration and correction factors),
to get flywheel power to use in this formula.
[ Edited on 25-1-2006 by dangerous ]
| Quote: | Originally
posted by westi
That's mad Alan.
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lohoon
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| posted on January 25th, 2006 at 06:36 PM |
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Isn't there a "table" that speed dudes use that considers final drive ratio + wheel diameter + top engine revs?
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modulus
A.k.a.: Peter Hill
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| posted on January 25th, 2006 at 06:48 PM |
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| Quote: | Originally
posted by lohoon
Isn't there a "table" that speed dudes use that considers final drive ratio + wheel diameter + top engine revs?
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Yes and no. What 'dangerous' is referring to above is a way of estimating trap speed at the end of 1/4 mile of full acceleration.
Of course, the car may go on to achieve a higher top speed, which can be calculated from the top gear ratio, final drive ratio, top rpm, tyre size
etc. *provided* that the horsepower curve of the engine is able at all points in the top gear rev range to deliver more kW than required by the sum of
rolling resistance (usually small) and aerodynamic resistance (usually big).
I can't guess what wombat wants to know, so I'll go with:- if you drop it from a C4 transporter at 10,000 m, it should top out at about 180 kph
before it hits the desert floor.
[ Edited on 25-1-06 by modulus ]
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dangerous
A.k.a.: Dave Butler Muffin Man
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| posted on January 25th, 2006 at 06:48 PM |
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Gear ratios can be used to calculate theoretical top speeds but
unless the engine makes enough power to overcome the frictional losses
(air and other), then it is just theory.
A 60 hp vw beetle would probably max out at less than 90mph
.....well unless "gravity is your co-pilot"
| Quote: | Originally
posted by westi
That's mad Alan.
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dangerous
A.k.a.: Dave Butler Muffin Man
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| posted on January 25th, 2006 at 06:50 PM |
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Well said Peter, you beat me to it and described it better.
| Quote: | Originally
posted by westi
That's mad Alan.
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VWCOOL
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| posted on January 25th, 2006 at 06:50 PM |
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Yeah - it's called a speedo :P
Pay your debts, CxxT
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speedster356
A.k.a.: Peter Mcleod
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| posted on January 25th, 2006 at 08:00 PM |
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If your looking for theoretical top then the final drive, tire size, and max engine revs are used. I have a formula some place that then uses your
theoretical top speed along with Cd, and frontal area and gives you the required HP to reach that top speed. This dosen't take into account rolling
resistance (tire on surface) but is used by the salt lake speed guys. Remember that drag squares by the velocity....:o
Spyder-WISD 07-09-05 11.6s @ 125 MPH
Speedster-WISD Nats 05 14.4s @ 89 MPH
Jet cruiser-Coogee 22-09-05 900 deg C @ 110,000 rpm
Weaseling out of things is what separates us from the animals....................Except the Weasel.
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