Slow progress but progress (DIY two seater tadpole trike, 9hp Honda diesel)

[solarguy]

Excellent.

And fast I might add.


I envisioned much the same vehicle and small diesel drivetrain, but chickened out because of the time involved.


Did I mention...excellent work.

troy

[freebeard]

Reverse gear?

Retro-rockets.

I see a Dymaxion.

How thick is the aluminum? Will it be compound-curved? I've only worked with samples of PolyMetal but I like it. The thermoplastic core would provide the thermal and acoustic damping Christ mentioned. It come in 3mm and 6mm with .007 aluminum skins. There is a MaxMetal product with thicker skins, single-sided PolyMetal and so forth.

Tesla apparently makes their side intrusion trusses with nested corrugated pieces (cribbed from NASA). You might put a layer with horizontal and/or vertical corrugations behind the skin.
________________

Since the stock torsion bars are about 200% of your requirement, just remove the upper grub screw at the center of the torsion bar and it will float freely and act as a stiff ant-roll bar...I think. And if you want to throw money at weight problems, the steel front torsion beam is available in aluminum (for offroad use in Calif.) as a sand buggy part.

[NeilBlanchard]

Originally Posted by elhigh

RE what Neil was saying about the original VW 1L - I remember reading the article where they described the prototype and how the chairman of VW drove it over 100km to a meeting. He didn't baby it, said it plugged right along at 110-120kph. That's about 75mph, not bad at all.

Quick acceleration will require good gear ratios. Small displacement diesels being relatively torquey but also narrow RPM range, that is tuned for high FE mean that it won't be quick.

If Phil's estimate is close, then it will also be very similar to the VW L1 in another important way, as well.

[user removed]

The engine is basically brand new. I went to DC when my oldest brother picked it up, it was brand new in the box and probably has less than 3 hours running time. He had it installed in a 6 wheeled off road vehicle but it kept snapping axles. Torque is rated at 15 foot pounds at 2500 RPM, max HP is 9 at 3600 RPM. With lightly loaded tires (about 40% of rated capacity with just a driver) and 3 wheels, the rolling resistance should be small.
The rating of 180 grams per shaft HP does not specify the RPM at which it is achieved but the max fuel consumption works out to .5 gal per hour.

With vehicle weight including a driver at 12-1300 pounds and first gear max speed at 23 MPH acceleration will not be great but I don't drive any of my vehicles that hard anyway.
Peak torque is 2500 RPM and top gear should be 55 MPH with that engine speed. With a theoretical top speed of 83 MPH and 23 max in 1st, that should work out to about a 12-15 MPH spread between each gear change at max speed of 3600 RPM, but I will probably shift just after peak torque so it should be about 16-23-36-49-55 in the individual gears to get to 55.

I figure anything after that is gravy, but with a very low CD, low mass, low rolling resistance, and low frontal area, it will be interesting to see what it will actually do. Chain drives and straight cut gear bike trannies are very efficient.

The torque is about what a 250 CC Honda Rebel produces and I know a Rebel will go 85 MPH, but ti is much lighter than this vehicle. I'm thinking it will be about a fast as a tractor trailer up to about 35-40 MPH. After that who knows but that will be fast enough.

I have driven my Fiesta through many tanks of fuel and never exceeded 3600 RPM.

regards
Mech

[Christ]

The 250cc Honda rebel will also have a much higher CD, although having less A probably... so you might come up about even on that. Difference being that the rebel is geared lower and builds torque much higher in the RPM range than the diesel does, so your setup being closer to 1:1 should actually be marginally more efficient in terms of driveline.

[aerohead]

Are you at about 52" for overall height?
And around 59" width?
I've got a power curve from 1998 from Honda R&D Co.,Ltd,for a 'Conventional' (thinking it's an Accord) and the Dream-3 solar racer.
I'd like to play around with some numbers.

[user removed]

Height would be 8 inches ground clearance plus 50 inches for the actual vehicle body. Width is right at 64 inches, so the front wheels can be covered with skirts. Best guess on frontal area is 60-65% of the Fiesta.

I remember reading a long time ago that a Honda CRX required 7 HP to go 55 MPH. That was the original 84 CRX 1.3 which one of the car rags drove at 55 MPH and got 72 MPG when the car first came out in the summer of 83. My Crx 1.5 was built in July 93 and it was serial number 1018. Bought it brand new when I was working at the Benz dealership just north of Houston.

The bottom will be flat except for the front and rear wheel openings.

regards
Mech

[NeilBlanchard]

If you can take a photo of the front of your vehicle with a fairly long lens, with the center of the lens about at the center of the vehicle, I can do an outline in DataCAD that can measure the frontal area.

[Xist]

Originally Posted by Old Mechanic

Width is right at 64 inches, so the front wheels can be covered with skirts. Best guess on frontal area is 60-65% of the Fiesta.

I really want to see how you do that!

[user removed]

Once we get everything lined up and functional, to the point where we can turn the front wheels and know precisely how far they will stick out from the frame then I will probably hand form them out of aluminum sheet. I am following two thought pathways right now.

1. Make them flush with the sides, then have them fold either up, hinged at the top, or out, hinged at the front. They can be activated by a linkage to the pittman arm on the steering box, or by the steering stop arm. The stops will have to be adjusted anyway since the tires rub on the upper control arm when you turn the steering as far as possible, so I have to reduce the travel with the stops anyway.

2. Make them fixed with minimal clearance from the wheels when turned to maximum lock. Hand formed aluminum, teardrop shaped falring back to the sides behind the wheels.

I am leaning to the first option since it would not increase the overall width and with the skirts perfectly following the shape of the rest of the vehicle it would be slightly more efficient. There is a perfect spot right above the wheel to mount a hinge like Basjoos has on his car. They could be spring loaded an contact the tires, but I would prefer to have them moved by the steering box. I was thinking about doing that with the headlight as well, but I don't want to get mired in complexity.

regards
Mech