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Discussion Starter · #1 · (Edited)
I am going to build another car. This is going to be a rail dragster. I am calling it Panic in Detroit, cause I hope it causes Detroit to shake up their act.

I have bought a super comp dragster that sits as a roller at 600lbs without driver. My target is to knock Larry McBride off the top spot before Shawn builds another vehicle.


The car was owned by a local fellow who made me an offer I couldn't refuse. The cage is a little small so I will be looking for a driver, unless I can figure out how to widen it.
NM0B8xY4Fs

my target specs are 1999lbs and a peak of 1battery horsepower (BHP) to pound (lb). Around 1999BHP in a 1999lb package. I would prefer to make it 1500BHP in a 1500lb car. But these DC motors are heavy and Netgain is still my sponsor so we are going with the tried and tested Warp series motors again. They have served me well. I may try to lighten them up a bit by taking some steel from the frames. We are also going to try a 2 into 1 gear box with 1:2 overdrive gears built in. I have two RFQ's out for that right now. Stay tuned.
 

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Hope to read more about this project, especially technical details. One suggestion (probably already well known) is to use a transverse mounted motor so that its torque will tend to push down on the nose while accelerating, unless there is a lot of weight there already, in which case you may want the torque to transfer to the rear traction wheels.
 

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What are you talking about :confused:
The motor rotation in the same direction as the wheels. Instead of Longitudinal (in length of vehicle) which would mean 90 degrees change of rotation.

This would cause a twisting torque in the chassis.

transverse



Longitudinal

 

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Thank you tomdb, but I fully understand the meaning of transverse.
If you now imagine the vehicle chasis, with the reaction torque created from a longitudinal engine, this makes the chassis want to twist when viewed from behind.

Now with transverse engines, the reacting forces will only be "visible" from a side view. You could thus setup your engine so it want to "bend" the rear axle forward.
 

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Now with transverse engines, the reacting forces will only be "visible" from a side view. You could thus setup your engine so it want to "bend" the rear axle forward.
From the side view, the rear axle is a point. How can you "bend" a point?

I want Paul, or, O.K., you, to explain this "motor so that its torque will tend to push down on the nose while accelerating".
 

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Every action has an equal and opposite reaction. When a motor accelerates, it creates a torsional force on the shaft in the direction of applied torque, while the housing exhibits an identical torque in the opposite direction. If the motor is mounted directly on the center of the rear axle, it will apply torque to the drive wheels to create forward thrust. This causes the front end to lift, causing a "wheelie". Of course, this is also observed with vehicles having a motor rotating on the axis of thrust, but its torque is delivered to the frame or the axle in the direction of rotation, which adds force on the wheels on one side and reduces force on the other.

With a standard differential, the driveshaft delivers the rotational torque it the point where the differential changes the direction of rotation, and thus delivers this force unequally to the drive wheels. Some vehicles use a "torque tube", which is mounted to the motor and/or frame near the motor, so that the torque is applied at that point rather than the drive wheels.
http://en.wikipedia.org/wiki/Torque_tube

The torque effect is not much noticed on four wheel vehicles used for normal driving purposes, and many newer vehicles have transverse mounted engines and front transaxles that pretty much eliminate this effect. But it is a factor for high performance vehicles, and also for motorcycles. There is a reason why you don't see many motorcycles with longitudinally mounted engines, although they do exist:
http://www.eng-tips.com/viewthread.cfm?qid=293190

Actually, the torque of a transverse mounted motor due to acceleration is probably insignificant compared to the forces of accelerating the vehicle, which will always tend to lift the nose up. The acceleration of the rotational mass of the motor's rotor is fairly small, but the direction of this force could be made more advantageous by using power transmission components that rotate the drive wheels in a direction opposite to the motor's rotation.
 

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Actually, the torque of a transverse mounted motor due to acceleration is probably insignificant compared to the forces of accelerating the vehicle, which will always tend to lift the nose up. The acceleration of the rotational mass of the motor's rotor is fairly small, but the direction of this force could be made more advantageous by using power transmission components that rotate the drive wheels in a direction opposite to the motor's rotation.
I don't buy into it. You have the angular momentum of the motor rotor and the change in that w/r/t time is torque which is summed (+ or -) with developed torque and delivered to the wheels for the resulting tractive effort. The direction of rotation of motor rotor w/r/t wheels is irrelevant to the reaction torque on the chassis around the drive axle and resulting lifting force on the nose.
 

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imagine you start a motor on the bench, the housing rocks in the direction opposite of shaft rotation (because the rotor has mass), that is all that sidewinder can do, get a little extra push from accelerating the rotor mass, only while it is accelerating (and used to push down on the rear, not the front).

However, having the rotor fore-aft provides some gyroscopic force longitudinally which also helps keep things level, whereas transverse doesn't. But it isn't a lot, otherwise trying to lift the nose would turn the car sideways.
 

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Discussion Starter · #14 ·
I saw one of the side winder dragsters in the Garlits musuem while I was in Ocala to watch the latest attempt to go 200mph. My mouth dropped open when I saw the side winder gear box was made by none other than the guys making my new overdrive unit. Wow, that was 50 years ago too. My new gear box is going to have a 10" drop, 1:2 full time overdrive and up to four motor input shafts into one or two output shafts. It would also make a nice tractor puller, monster truck gear box, etc...
We will be putting two Transpulse9 and two Impulse9 motors into one overdriven output shaft. That will feed a Lenco 3 speed transmission which I already own and a 4.56 rear gear.
So far ready to go is
The dragster roller
The two impulse motors
The battery from AnB or DCP
The controllers from AnB or DCP
The DC/DC converter from AnB
The contactors and fuses from AnB
Waiting on the gearbox to be completed
Waiting on the two TransImpulse9 to be built.

Then just assembling all that.
I would like to build a drop in motor/transmission/battery/controller system that would fit either PiD or AnB
It could then be duplicated and dropped into any dragster.

We are targeting Larry McBride's best speed.
PiD is a 7.5 second dragster, my math says we can just get to 201mph in 7.5seconds. Several dragsters in the Museum went 200mph in 7.6 seconds back in the day.
 

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That's only because of the driveshaft transmitting torque to the axle, and that would exist no matter which way the engine is mounted. A torque tube transmits the torque to the frame of the vehicle at the engine, so the relative twisting of the frame and the drive train as shown here would not occur. I'm not sure if this would provide equal force on both rear tires, however.

Here are rather detailed discussions:
http://www.hotrod.com/how-to/wheels-tires/chassis-tuning-tire-traction/
http://www.wallaceracing.com/leafspringtraction.htm

Also pinion angle:
http://www.dragzine.com/tech-stories/drivetrain-angles-increase-torque-and-improving-hook/

Other discussion:
http://www.eng-tips.com/viewthread.cfm?qid=49028
http://www.eng-tips.com/viewthread.cfm?qid=147640
 

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I understand lifting the nose no matter how you transmit the power, but shouldnt a transverse setup eliminate the cars tendency to lift onto the right rear tire? (A full transverse setup that uses a transverse transmission like most FWD cars)
 

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Discussion Starter · #18 ·

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Discussion Starter · #19 ·
BTW, We changed to a Top Dragster chassis (no longer the supercomp, that is in storage if someone wants me to build one for them.)
We are already certed to 6.0 seconds done last month.
 
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