|Subject:||adjustments to engine stats|
|Date:||Fri, 12 Feb 93 12:48:11 EST|
was kicked off the system for no apparent reason. 2nd Someone switched the box
connecting me to the network. So needless to say I am not a happy camper. I
apologize in advance for any incomplete explainastions. And sorry for venting
here. I also apologize for copying most of Hayden's last post.
>>>>>>>From: R Andrew Hayden <rahayden@*****.WEEG.UIOWA.EDU>
Name Weight (in kg) NPUs Body
Mini 400 800 1
Small 700 1400 1
Medium 1000 2000 2
Large 1400 2800 3
X-Large 1900 3800 4
I like the body and Weight coulmns put reserve judgement on the NPUs until we
have established more firmly other areas of design.
I want to build a Large car. [stuff deleted]
Total weight without the engine is 2400kg.
Of the 2800 NPUs, I've allocated 800 to engine. Since I've got to
have some space for fuel and whatever engine accessories I add,
lets put in a 600 MPU engine.
Lets figure out our engine power. I'm going to Carter's equations:
Gas Power = (NPU^2) * 1.75
Elec Power = NPU^2
600 NPU Gas = 630,000<<<<<
OK, here's where my $0.02 start. I believe that we should measure power
"real" units of power such as watts. We can do this by simply changing our
"fudge fator" to .3 rather then 1.75. Therefore:
Gas Power (watts) = (NPU^2) * 0.3
and a 600 NPU engine would 108,000 watts (0 horsepower). typical for an
auto engine in 1993. (I know this may not be typical in 2054, but its a
reasonable place to start.)
>>>>>600 NPU Elec= 360,000
First thing I see is that electric is too wimpy. You are talking
about electric being about .5x as powerful per NPU as a gas
engine. I don't thing this is right. Perhaps use (NPU^2) * 1.25
for electric power?<<<<<
For this "fudge facto" (FF) I suggest .25 @ 600 NPU, power (elec)= 90,000
watts (0 hrp).
>>>>>Next we'll figure out our cruising speed. The formula that seemed
to agreed upon is:
Cruise Speed = Power / Weight
This will give us a cruising speed of 210 km/hour. That means this
car can hit around 130mph without breaking a sweat.<<<<
Because of the FF was change in the power eq. we need to add one here. It
looks like we needed one anyway with the high we were getting. Therefore I
Cruise speed = Power*2/weight
This gives a cruise speed of 72 kph for the 108,000 hrp engine and 60 kph for
the 90,000 hrp engine. Seems more reasonable to but its still higher than RBB.
Two equations are being batted around:
RS = Cruising Speed * 2
RS = Cruising Speed * 3
This would yield 420 and 630 respectively. Ie, you redline at
about 260mph, which is faster than most Indy cars. OOPS<<<<<
I'll only with the gas engine from now on. Redline speeds for the gas engine
would be 144 or 216 kph. Again more reasonable. I perfer the *3 version to
be able use RBB pre fab cars and our cars with the same set of rules (what
ever they may turn out to be).
The suggestion was:
Economy = Power / 2 (weight*eNPU)
or, for our car
Economy = 630,000 / 3,600,000
Economy = .175 km/unit<<<<
I purpose the following formula for economy:
Economy = (Cruising speed * 10,000) / power
67 km/l (41 mpg) for the car we are considering a little high for shadow run
standards but I think reasonable.
I do realize there may be problems with this formula because it does reduce to:
Economy = 20,000/ weight
If any one is interested in how I derived this equation please let me know.
Its derivation is more mathematically sound then the one for speed. ie. no
FF's. The 10,000 is a real conversion factor.
>>>>>[other FF examples deleted]
Now, with equations like this, it would seem that a 600npu engine
is overpowering the car (based on speed). Just for kicks, I'll
compute the above with a 400npu engine and the 1.25 multiplier (but
still a 3000kg vehicle)
Power = 200,000
Cruising= 66 km/h (a mere ~40mph)
Redline = 132 or 198<<<<
Good idea, I'll try a 400NPU engine with my equations
Power = 48,000 (64 hrp)
cruising = 32 kph (yuck)
Redline = 64 or 96
Well 400NPU is definently to small for my system. maybe it would work for a
motor cycle. Oh well it was my first attempt let me know what you think
meanwhile I'll keep working.