the 70lber batmobile

[Eric]

Yea the kart is kind of compact, if I were building a custom cart I would put the wheels back another foot and a half, a 20 lb dumbell plate right in the front would help a bit.

Having the engine close to the tank wont be a problem if you have the heat sheild. Aluminum will reflect 97% of the heat away, and the tank will be getting cold from the expansion.

The important thing is to slowly work up to the speed you want to go at over a few runs to make sure the kart can handle everything.

A roll cage is always a good idea, especially at high speeds.

I'd offer to help you build it but its kind of hard 3000 miles away lol :)

Eric

[Mark 42]

Something like this...

http://www.aardvark.co.nz/pjet/

http://www.youtube.com/watch?v=AonvMWaqNLY

http://www.youtube.com/watch?v=clOmc3WI5fk

http://purplesagetradingpost.com/sumner ... age-1.html

[tufty]

I think I'd go asymmetric. Jet faired and mounted down the centre of the vehicle, pilot prone in a nacelle between fore and aft wheels on one side, fuel on the other. 2 fuel tanks, one for the pulsejet itself and one for one of Eric's ramjet afterburners :) Wheels large and thin, to reduce rolling resistance, and improve visibility. That way you could keep it all very low, and probably get a bit of ground effect in there as well if going for high speeds. Probably not terribly good for handling, and you'd need to worry about aerodynamics to stop it flipping sideways, but likely the best way to deal with a flat-out straight run. No on-wheel brakes (a pair of side-mounted drag chutes), minimal steering, and dead-man-handle controls.

I could design it, but I'm not sure I'd have the balls to ride it :)

Simon

[adam]

hey eric since this engine i have is your design, do you have any good plans for a thrust augmenter, something that will increase thrust pretty good on the intake section of the engine and not be too much drag for only speed less than 90 mph? well i got videos yesterday of me doing a test run, they were really crapy so i didnt post them because the propane tank i have recieved when i exchanged my old tank haves a stupid safety thing in the valve so i was only getting like 60% throttle runs down the road and the speeds were not that exciteing, i think i was only doing about 30 mph and the engine wasnt even half the power it produses i beleive, i made a perfect heat sheild and it works pretty good, down side is that it is galvanized steel so i guess ill have to lett it burn off. i will post some faster runs here in a little bit when i get my new propane tank

[Jim Berquist]

Adam: After you get it firmed up and Zooming, Maybe you could talk Eric into Test running this for him? Ram Jet Powered by your Pulse Jet!


http://www.youtube.com/watch?v=b0KJwa5iWTY


Edit: It would be nice to know how much P.J. Thrust is lost verses How Much Ram Jet Thrust is realized with this set up. I would think the gain will out weigh the loss!

Jim

[adam]

can anyone in here let me know if it is too dangerous to mount the propane tank about 7 inches from the u bend section of the pulse jet while its running and with no heat sheild covering it because this is the only area i can succefully mount it with out haveint to re-do any weldings to the frame.

[Jim Berquist]

Hi Adam! Sounds a bit close to me! Like Eric said, The bottle is going be chilling it's self while discharging.. I would obtain some of that aluminum thermal wrap for Duct work... Aluminum bubble wrap type stuff and blanket the bottle....


Jim

[Eric]

7" without a heat sheild is gonna be too close, the tank would probably be fine but the fuel line would melt.

Home depot type stores sell rolls of aluminum flashing for roofs and stuff, you can cut it with a good pair of scissors and form by hand.

Did you lower those mounts?

Eric

[adam]

yes i cut those stupid mounts off because like you said it was way to high up, i cut those little rods all the way up to the combustion chamber and just welded two straight rods to the outer frame you made around the engine, the rods are horizontal so the engine bolts to the plate the same way using the 4 u bolts, the combustion chamber is now sitting about less than half an inch from that big steel plate or platform i have on the back so its alot lower and it looks better too, but now since the engine is sitting lower and with my heat shied installed, the engine is sitting right above the propane tank and the heat shield is kinda in the way of the propane tank and even with the heat shield it looks as thow it is still way to close, just look at the pics posted with the engine how it used to be and imagine that propane bottle sitting how it is in the back but with the combustion chamber now sitting on that steel plate and the u bend is going to be going right over it, thats really close to me. but i know you have years of experience and know your stuff so i guess i will try and see if a heat shield will work, its just kinda scary cuz i dont want it to blow the tank up, even with the tank freezing when its turned upside down man that engine being that close dont look like it will let that tank freeze! and the tank is upside down by the way so is that still going to burn the hose because its a little further away from the engine or did you think the tank was going to be right side up?.

[Mark 42]

Can you put the tank on the front of the kart?

I just grabbed 3 large coffee cans from the breakroom at work...
this gives me about 2-1/2 square feet of sheet metal that is
free, and relfects heat better than aluminum. I have to make
a heat shield and motor mounts for my Elektra II tonight, and
since I don't want to use an evening to go to the hardware
store, it seemed like a good way to go.

I tend to use what I have, or what I can get for free, whenever I can.

[_Rahul_]

Well .. I assume its all done .. so I will look like a dumb telling something ..
But wont the go-cart deliver the max propelling force if the engine was in line with the go-cart .. just behined the black cart .. I mean just like it looks in the first pic!
Anyways .. I think It can be bad too .. mostly for bumpy roads ..
Hope you get wat I have to say ..

[_Rahul_]

Okay .. Off topic .. but I came across this!

reminds me of bat-motorbike .. although the guy couldnt get it started .. but It seems it had enough power in the engines!

http://www.youtube.com/watch?v=6wv-47_CVhY

The motorbike does looks very cool!

[Mark 42]

Sometimes they do run...

http://www.youtube.com/watch?v=yy4KH88tLSY

http://www.youtube.com/watch?v=e4Ufhopd1lY

[Jim Berquist]

Yep some times we get things right!

http://www.wright-house.com/wright-brot ... 903.htmlep!


Jim

[Mark 42]

Yep some times we get things right!
http://www.wright-house.com/wright-brot ... /1903.html

Yes, even though it is done by building upon the work of others...
Like Otto lilienthal and John Montgomery.

I was thinking about the issues of fuel getting too cold and
freezing up, and of shielding the propane tank from dangerous
temperatures.

First, insulating the cylinder won't help to keep the fuel
from freezing. Heat can only move from hot to cold.
Unless the atmosphere is colder than the surface of the
metal tank, allowing the tank to have contact with air will
serve to add heat to the cold fuel. The warmer the atmosphere
the more heat transfer will occur.

If you are running an engine in Winnipeg in the winter, you might
have a reason to insulate the tank to avoid freezing, but most of
the time the air is warmer than the surface of the propane tank.
(which is right around the temp of the condensation on the tank).

As far as protecting from the heat of the engine... that would be
a good plan. I would not feel safe using the hot engine to warm
the fuel, except in one possible scenario.

If you could get a metal bucket and put the tank inside of it and fill
it with water, then the water between the bucket and the tank would
act as a jacket that would stabilize the temperatures and still allow
some heat transfer.

I don't know if a 10 lb cylinder would be adequate to supply
fuel for a long enough run, but it would be easier to find a metal
bucket that would fit.

The big drawback is weight. An aluminium bucket would work
well, but the water still adds a fair amount of weight.

BTW, a metal heat shield of several thin layers will work better
than one thick layer... which is another nice thing about using
coffee cans for a heat shield. Larger panels of sheet metal is
easier to work with, but I like the ribbing that coffee cans have
to stiffen the thin metal.