Author Topic: Hybrid Supermileage Car  (Read 3295 times)

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taylorp035

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Hybrid Supermileage Car
« on: August 12, 2015, 10:25:21 AM »
This year the team took two cars to competition.  One of the cars featured a series hybrid power train and the other was a revamped version of the 2012 car.  Here's some of the info for the hybrid:

Modified Briggs 148cc engine to a large Ampflow dc motor that acted both as the starter and generator (electrically separated and operated by some large relays).  Then the generated power was evened out by some 1 F caps (largest by the rules) and then went to two brushless motor ESC's and two large out runner motors that were attached to the front drive wheels with bendixs.

The car was surprisingly reliable and managed 479 mpg and has drive probably 75 miles.  Not bad considering the many efficiency losses when converting the power and the heavier weight compared to previous cars(double the 2013/2014 car).

Acceleration was very good, since it had lots of traction on the front wheels.  Data recording on the ESC's were showing 800w on each wheel. 

It took about 100 man hours to wire the car and the team was very pleased to see that it all worked on the first try when the engine was started.  Here is a pic while the technical inspector was carefully looking over the car.



The car was also different since it had rear wheel steering, which worked quite well compared to previous attempts with that design.  As you can see in the picture, there wasn't much space left over in the car....   And the driver has a lot to think about and many buttons and leavers to push. 

SparWeb

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Re: Hybrid Supermileage Car
« Reply #1 on: August 13, 2015, 08:16:23 PM »
That's one slick machine!
I can barely make out the B+S engine for all the other stuff inside.
How are things like handling, braking, etc?
No one believes the theory except the one who developed it.  Everyone believes the experiment except the one who ran it.

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taylorp035

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Re: Hybrid Supermileage Car
« Reply #2 on: August 24, 2015, 07:48:33 PM »
The handling was very different since it was rear wheel steer.... and a bit different from other rear wheel vehicles due to the length and the odd geometry and very limited steering angle.  A very stiff chassis helped the cause a lot.  It passed the slalom test easily and the brakes were quite good since it had large disc brakes up front.  On the test platform, the car could do a burnout and lock up the tires under braking.  The car also passed the tilt test, which was impressive considering the extra weight added up high in terms of electronics.  But the 1-2" wider front track width probably made it pass.

The electric motors up front could of done 2-3kw each, but the 148 cc Briggs was maxed out.  I can say the acceleration on the test platform using the batteries was pretty intense.

I don't have any other pictures of the inside of the car.  But as one can see, there was a lot of thought that went into the packaging of all the components.  As you near the upper levels of the supermileage competition, getting everything is a trade-off for making the components and the driver fit. The competition has made it even more difficult with the addition of the new 206 cc engine, so I bet a lot more teams are going to be motivated to modify the engine for dimensional, weight and efficiency improvements.

oscar11

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Re: Hybrid Supermileage Car
« Reply #3 on: August 26, 2015, 06:56:28 PM »
Could you modify the Briggs to a six stroke engine?

taylorp035

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Re: Hybrid Supermileage Car
« Reply #4 on: August 27, 2015, 11:29:10 AM »
Could you modify the Briggs to a six stroke engine?
No, the SAE rules state the engine must be a 4 stroke.  Else, you can modify the engine pretty much in any way you feel like.

SparWeb

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Re: Hybrid Supermileage Car
« Reply #5 on: August 28, 2015, 01:00:42 PM »
It looks like it has the "convential" valve head on it.  The one you built last year, that is.

How far have you pursued your rotary valve concept?  Is it ready to try on the supermileage?
No one believes the theory except the one who developed it.  Everyone believes the experiment except the one who ran it.

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taylorp035

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Re: Hybrid Supermileage Car
« Reply #6 on: August 31, 2015, 09:56:06 AM »
That engine is the pushrod - rocker engine that was used in 2012 and 2013.  It was selected since it had lots of horsepower.

The rotary valve concept is still being pursed at an increased pace.  I'm now on the 5th version (1,2,3.0,3.1, & 3.2) of the design.  Next up is a 1999 BMW 328is, of which I finished the design for and we are validating some of the design features on the go-kart before spending too much money.

The students in supermileage may attempt a rotary valve engine in the future, but probably not right away since the competition is most likely requiring a new base Briggs engine this year and that means a new car and some serious engine modifications for it to be competitive.

There are some other videos of related things on my youtube channel as well.

https://www.youtube.com/watch?v=J_pVPg29Ylw