Another jet-kart fool

[Tiercel]

As I mentioned in another topic, me and a mate are buiding a jet powered go-kart. Originally we were going to use a pulse jet, but due to advice from Bruno Ogorelec we decided to change to a valveless.


Just a few questions:

1. Will this thing actually power a go-kart at a decent speed?
2. From what Ive figured, its only 76cm long, is this right?
3. Is there a set distance that the spark plug must be set at?
4. What fuels can it use other than propane?

[larry cottrill]

Tiercel -

That's quite small - a good engine to build if you've never done one before, but only good for a couple of HP. You'll need something significantly bigger for good performance on even a lightweight cart. Note also that you'd need some kind of recuperator to recover all the energy you can as thrust.

Take a look at Eric's scaled-up engines:
http://www.pulse-jets.com/phpbb2/viewtopic.php?t=1264
http://www.pulse-jets.com/phpbb2/viewtopic.php?t=1627

That's about the size you'd need, whether you go with Chinese, FWE or Lockwood design [these are still vapor fueled, though]. For a very small cart, you might get away with a 2-to-1 re-scaling of the FWE, if you don't need hot performance. Take careful note [in the second thread above] of what he says about the dangers of this noise level!

Right now, there is no proven practical method of liquid fueling any valveless jet that I know of. This is being worked on experimentally, though, so we might have something usable before long.

L Cottrill

[Tiercel]

Ahh.... That whole body vibration stuff is pretty nasty... Is there any sort of defence you can easily get hold of to stop all that organ destroying, spine vibrating internal bleeding stuff?

[larry cottrill]

Ahh.... That whole body vibration stuff is pretty nasty... Is there any sort of defence you can easily get hold of to stop all that organ destroying, spine vibrating internal bleeding stuff?

It's difficult with something like a cart, because you're positioned so close to the engine. What I would try to do is have the engine nestled inside a V-shaped reflective panel that would reflect the side noise upward. This would need to be something pretty rigid, like a steel panel with a gridwork of steel bracing behind it to keep it light.

Others may offer additional / alternate ideas.

L Cottrill

[steve]

I'm glad you like the plans I drew up, but as larry said, it will only produce a small amount of thrust (about 1.5lbs) and is more suited to a model aircraft then a gokart.

If you look about halfway down this page there is a set of dimentions for a 20 lb thrust lockwood engine that I built last year:
http://www.pulse-jets.com/phpbb2/viewto ... 66&start=0

you will probably need two of them to make a gokart move at any considderable speed though:
http://www.pulse-jets.com/phpbb2/viewto ... 25&start=0

you could also try building an Escopette, which also produces around 20lbs thrust, but is quite long (see pictures)

[Tiercel]

thanks for the designs!

Weve started looking at differant ways to control the fuel input and insert some sort of emergency fuel shut off so if it all goes the way of the pear, we can shut the engine down quite quickly. My idea was to put a pipe from the gas canister to a valve next to the driver, then from the other side of the valve it backtracks to the jet. This way the valve doubles s a throttle. Would this work, or is there a better way?

[Rossco]

Ben, i do the same thing when operating an engine for a crowd!
But my test rig will pop and fire back into life instantly full rev when red hot. Quite ammusing when everyones taken there fingers out of their ears and started talking back at the normal level!

Rossco

[Tiercel]

Just out of interest, can these engines explode and if an engine did explode, where does the blast go? Me and my mate think that it would either go downwards , or more likely, as the air is being rushed through, it would explode backwards. Or is it completely unpredictable?

Its quite important, as we still need some of our body parts, were too young to lose any!

[Bruno Ogorelec]

Just out of interest, can these engines explode and if an engine did explode, where does the blast go? Me and my mate think that it would either go downwards , or more likely, as the air is being rushed through, it would explode backwards. Or is it completely unpredictable?

Its quite important, as we still need some of our body parts, were too young to lose any!

I have not heard of a single one exploding in 35 years. In fact, they sometimes implode -- the tube goes flat. Looks like they stand the overpressure much better than underpressure .

[Russel]

hi, i'm Terciels mate Russel, i have been wondering, how do you mount the 'Escopette' engine, i suppose it has to be easily accesable (and not near any of my limbs), sound proofing has to be taken into account, and starting the thing safely? we havent built a jet before so all of this stuff is new to us.

Welding, is this going to be diffucult, i can weld allready, but is there a special technique, or thing i would have to remeber, i.e., weld disrupting airflow inside the jet engine?

also "Fire Extingushers", is there a favored method or type of extinquisher?, i would think a CO2, or foam would be sutable, with a water extinguisher on the side in case of any accidents (setting fields/clothes/pets, etc, etc on fire...)

[Bruno Ogorelec]

hi, i'm Terciels mate Russel, i have been wondering, how do you mount the 'Escopette' engine, i suppose it has to be easily accesable (and not near any of my limbs), sound proofing has to be taken into account, and starting the thing safely? we havent built a jet before so all of this stuff is new to us.

Well, I can tell you something on these two points; other people have more knowledge about teh others.

(1) Mounting of the engine must be partly flexible. Namely, you have to have a fixed mounting at some point where the engine will be pushing the kart. It is probably a good idea to provide this mounting somewhere at the front part of the engine. Perhaps you can weld a bracked to the side of the combustion chamber and then fix the bracket to the cart with bolts.

The rear part of the engine must be fixed so that it will not move to the left or right or up and down, but it has to be free to move a little fore and aft. Namely, when it heats up, it will stretch. If you fix it at both ends, it will bend and maybe buckle. There are many ways to do this.

(2) Soundproofing. You can forget about this. Pulsejets are so loud that there is no way you can do anything with soundproofing on a kart. You'd have to use more soundproofing than the kart will carry. You just have to resign yourself to the terrible noise -- probably much worse than anything you have ever done. You absolutely must have proper ear protectors, like the ones used in industry. I am telling you this very seriously -- your hearing will be forever impaired if you don't take this precaution. The noise made by rockets and jet engines is nothing compared to this.

[luc]

Hi Tiercel

As I mentioned in another topic, me and a mate are buiding a jet powered go-kart. Originally we were going to use a pulse jet, but due to advice from Bruno Ogorelec we decided to change to a valveless.

Just a few questions:

1. Will this thing actually power a go-kart at a decent speed?
2. From what Ive figured, its only 76cm long, is this right?
3. Is there a set distance that the spark plug must be set at?
4. What fuels can it use other than propane?

Why don't you use a pressurejet ... He he he. The 130R (130 pounds of thrust) will push you allright.

Actually, after when Viv and I will make enought money to pay our groceries, we have a project to build our self a Conception GLC inc. promotional Jet Car ... He he he.

My preliminary design involve 4 x 130R pressurejet in order to get a good 520 pounds of thrust. So, if we are cautious not to exceed the 520 pounds weight mark with our car (Including pilot, frame, nitrogen bottle and propane bottle), we should get a good thrust to weight ratio of 1 to 1 ... Like an F-16.

Understand this, our goals here is not to make a nice promenade car and wave a peoples arround. Our goals is to make ALOT of noise to attrack attention (Publicity ... He he he), generate ALOT of heat and flames ...

And get the hell out of that starting line box and beat any snow mobile or race car to the finish line.

We actually have 2 ski-doo frame here and all the sheet metal we want ... We just need time and money.

Nowww ... Who want to pilot this thing ... He he he.

Cya,

Luc

[Anthony]

Nowww ... Who want to pilot this thing ... He he he.

Cya,

Luc

Oh, I am so diriving it if you want to! It'd be hella fun with the current weather! Hehe.

[Eric]

Bruno,
While I agree that there wouldnt be any way to sound proof it so that you could not wear ear protection, I think even a thin barrier would provide a lot of protection for your body.

I tried a bunch of things, plywood, metal sheilds, and even a big sheet of plexiglass. To try to make the cockpit totally quiet is a totally futile attempt, but just taking the edge off of each explosion really seems to go a long way. I fired up the big chinese and stood at the bad spots behind the plexiglass barrier, i could feel the barrier vibrating like hell, but my body wasnt at all.

I think if you guys used even a thin sheet of anealed copper you could form it to some pretty odd shapes with ease and get enough protection from direct sound. You would still need hearing protection, and probably nice padded seats but you should be fine.

Eric

[larry cottrill]

Bruno, I have to agree with Eric on this one. Even something light would effect a lot of protection, if properly shaped and positioned. Just effectively reflecting the high-frequency harmonics would do a lot of good. To me, what would be ideal would be to longitudinally split a corrugated pipe in half, and position the half shell so it shields the low-lying driver while reflecting the noise outward and upward. This would be wonderful if such a thing could be found made from aluminum, since that would be lighter for its strength and MUCH more heat reflective, as well. Probably, no such thing exists ...

L Cottrill