Pulsejet vs Turbine

[JetSet]

Hello.

I am looking to build a jet powered go-kart (and later other forms of transport). The dielema i have is which type of jet to use. I can see pros and cons of each, but wondered what you guys think;

Turbine
- Made from a turbocharger.
- Provides a lot of thrust
- Quite efficient
- Catastrophes very rare, but very dangerous if it did occur
- F.O.D. a problem.

Pulseject
- Probably a lockwood
- Rediculously loud
- More fuel?
- Safer? (just split)?


I am more knowledgeable about gas turbines, but i havent made either jets yet. I will obviously be making a few experimentary engines first. I havent thought about exactly how much thrust will be needed, but that wont matter for the time being.

Up untill now I was pretty much set on the turbine, but, although no-one has been seriously injured by one yet, the "what if's" are creeping in :wink: :oops:

Any thoughts?
Thanks.

[Viv]

Good list but you left off a major item i think and thats complexity:-) the Lockwood option is just an empty set of tubes in comparison to the turbine.

Fuel is an issue but you could add a little complexity and run the lockwood on liquid fuel, still a lot but may be better from the standpoint of running time against a propane bottle.

As to noise well you are going to have a problem running any kind of jet in the UK so first find out were you are going to test then decide what you are going to build, a turbo based project is still going to come in at over 125 dba, we know from experiance a Lockwood can be heard for a few miles:-)

Viv

[paul skinner]

Good list but you left off a major item i think and thats complexity:-) the Lockwood option is just an empty set of tubes in comparison to the turbine.

Fuel is an issue but you could add a little complexity and run the lockwood on liquid fuel, still a lot but may be better from the standpoint of running time against a propane bottle.

As to noise well you are going to have a problem running any kind of jet in the UK so first find out were you are going to test then decide what you are going to build, a turbo based project is still going to come in at over 125 dba, we know from experiance a Lockwood can be heard for a few miles:-)

Viv

And I'd have to back up Viv's opinion. As Horace can tell you, building a jet (even from a scrap turbo) is a complex and costly undertaking. Unless you have access to mill-drill-lathe and a tig torch, access to the proper ceramic bearings, access to the proper lubricants, your looking at a very costly paper weight. A lockwood is dead simple (compared to a jet) and will cost you little in materials and labour.

[JetSet]

Thanks.

I will leave the turbine for a rainy day then. The more i think about it, the better a pulsejet sounds.

Running from liquid fuel sounds like a good idea, I assume this would require a pump and atomising nozzle? I will have a read.

Noise was a concern. I live in a town, but thought i could keep the length of test runs right down and take it to the middle of nowhere for anything longer.

Thanks for your help.

[skyfrog]

And I'd have to back up Viv's opinion. As Horace can tell you, building a jet (even from a scrap turbo) is a complex and costly undertaking. Unless you have access to mill-drill-lathe and a tig torch, access to the proper ceramic bearings, access to the proper lubricants, your looking at a very costly paper weight. A lockwood is dead simple (compared to a jet) and will cost you little in materials and labour.

Cannot agree more. Turbine as a hobby is not only complex, costly, but also time consuming too, all because it has deadly attraction for those curious, eager and fascinated people. I as an example end up have to give up my day time job and dedicated myself to turbine business for living. :-)

[jmhdx]

Hi Jetset, did you see the Scrapheap Challenge episode where both ideas were tried? Bruce Simpson built a lockwood the other team a turbo jet, the lockwood valveless won becuase there were no parts to fail, it's almost a hollow tube. I think the speeds were in the 40-50mph range.
I live within earshot of Santapod where they were run and I can assure that you would not believe how loud the pulse-jet was, few places will allow for that level of noise.
Still bloody good fun never the less.
I have a couple of clips from the programme but have trouble posting them. Will email them if you like.
Regards Mike.

[Viv]

Thanks.

Noise was a concern. I live in a town, but thought i could keep the length of test runs right down and take it to the middle of nowhere for anything longer.

Thanks for your help.

ROFL!

Sorry:-) Nick and I used to try that kind of testing but after the entire population of a small Somerset village turned up at the bottom of his garden to find out what the ucking noise was we were more than just a little encouraged by his wife to move testing some were else:-)

Try and find a small airodrome as they wont mind the noise and they will have a license and a runway to play on, join the flying club and offer to turn up at airport events with it as well, lots of these little places do all sorts of things and would be glad to see you.

Viv

[JetSet]

ROFL!

Sorry:-) Nick and I used to try that kind of testing but after the entire population of a small Somerset village turned up at the bottom of his garden to find out what the ucking noise was we were more than just a little encouraged by his wife to move testing some were else:-)

I was affraid you would would say that, which is probably why i left it off the initial post :lol:

Regarding the aerodrome, as far as I am aware, there isnt anything decent . The local runway/airport (Rochester) is grass and on the outskirts of a city :oops:

Is anyone here doing the same thing and from the South East of the UK? :-)

Thanks.

[Viv]

ROFL!

Sorry:-) Nick and I used to try that kind of testing but after the entire population of a small Somerset village turned up at the bottom of his garden to find out what the ucking noise was we were more than just a little encouraged by his wife to move testing some were else:-)

I was affraid you would would say that, which is probably why i left it off the initial post :lol:

Regarding the aerodrome, as far as I am aware, there isnt anything decent . The local runway/airport (Rochester) is grass and on the outskirts of a city :oops:

Is anyone here doing the same thing and from the South East of the UK? :-)

Thanks.

I can only think there must be a large selection in your area dating from the second world war, do a google search agianst local flying clubs that should yeald some results.

I used to live in Oxford and we had enough to trip over:-) and with concrete runways, the Americans built concrete runways for the B17s.

A runway is still the best option but a long private farm road is another as long as they are arable farmerrs not beef:-)

Also try glider clubs as they may be able to help.

Viv

[Mark]

Speaking of sound, yesterday I was Miking it, with the five easy pieces plumbing pipe wonder, and even though I was wearing good ear muffs, I noticed my ears might have picked up some other frequency even though the muffs seemed to cancel out any loud noises. Has anyone experienced this effect? My ears felt a certain something even though the sound was very mild wearing ear muffs. That is, later in the day, my ears didn't hurt, but they were saying something to me, if that makes any sense.
Erring on the side of caution,
Mark

[Mark]

PS It might be advisable to wear ear plugs and ear muffs and a gigantic pillow over your ears if you want to cancel out all frequencies. I've noticed that more sound is canceled out if I am mowing my lawn by wearing ear plugs, but with my pulsejets it "seems" the noise is dampened tremendously wearing ear muffs, it's so surprising to hear the actual sound when you take them off. What does it all mean?
Mark

[paul skinner]

PS It might be advisable to wear ear plugs and ear muffs and a gigantic pillow over your ears if you want to cancel out all frequencies. I've noticed that more sound is canceled out if I am mowing my lawn by wearing ear plugs, but with my pulsejets it "seems" the noise is dampened tremendously wearing ear muffs, it's so surprising to hear the actual sound when you take them off. What does it all mean?
Mark

Talking about episodes, this reminds me of that episode of "Mythbusters", where they were investigating the myth of the brown sound. I'm not sure if a lockwood would make you "lose control of your bowels"...but it sure makes the neighbours shite their pants.

[Hank]

Thanks.

I will leave the turbine for a rainy day then. The more i think about it, the better a pulsejet sounds. (A pun, I take it?)

Running from liquid fuel sounds like a good idea, I assume this would require a pump and atomising nozzle? I will have a read. (Pressurized fuel tankage with fuel control by regulator is the way to go. This leaves you another danger to plan for, i.e., tanks strong enough to withstand an internal pressure of 100 p.s.i. or better.)


Noise was a concern. I live in a town, but thought i could keep the length of test runs right down and take it to the middle of nowhere for anything longer.

(Middle of nowhere? Try a test run parallelling Hadrians Wall.)

Thanks for your help.

( )

[JetSet]

I will leave the turbine for a rainy day then. The more i think about it, the better a pulsejet sounds. (A pun, I take it?)

HEHE, I didnt realise :P

Pressurized fuel tankage with fuel control by regulator is the way to go. This leaves you another danger to plan for, i.e., tanks strong enough to withstand an internal pressure of 100 p.s.i. or better.

I did a quick search and couldnt find much, but it sounds like an interesting method. The regulator is easy enough to find though :-)

Middle of nowhere? Try a test run parallelling Hadrians Wall.

It would be good, but I couldnt live further away from Hadrians Wall :lol:


Thanks for the help everyone!!

[nmasters]

even though I was wearing good ear muffs, I noticed my ears might have picked up some other frequency even though the muffs seemed to cancel out any loud noises.

Bone vibrating sound :!: It's conducted to you ears by your jaw. Your ears can't translate it into nerve impulses but it is shaking the hell out of those little bones nonetheless. A hard rubber mouth piece may absorb some of the energy from your teeth. A full face helmet with dense, tight fitting, padding might also help.