"Thunderchine" 55 lb thrust pulsejet plans

[larry cottrill]

CONGRATULATIONS, Geltlemen! I would say your skill, patience and effort have been rewarded nicely!

Grim, you may not have been able to hang out with her for long, but I'm sure that's a run you will never forget! Nice work, man!

L Cottrill

[GRIM]

Heres a couple of photos of the fuel setup , as used for the initial run ,

M is not keen on the centering tabs, I agree, they are covenient but likely produce an intake restriction,

This set up may not be optimum , I was unable to get her to flame out on vapour , even with a 100lb gas cylinder and 115 psig static pressure ,
I was unable to experiment with injector positioning ,

Larger orifices may allow max thrust on vapour and will depend heavily upon ambient temperature ,

I intend to experiment with liquid propane , and liquid hydrocarbons , This will progress as time and money allow , and of course the all important thrust testing ,

I do hope the succesful running of this engine provides inspiration for others to do the same ,
BUT PLEASE USE THE PDF PLANS, I can verify that there is nothing to be gained from plotting full size except a lot of hard work ,

A small but noteworthy point is that if you are careful with your nesting , the component parts for this engine can be cut from a sheet of steel just a little over 1m2,

Thanks Larry , no I shant forget that run!

[Rossco]

Grim,

Congrats on the run, pity about being shut down. This is the way of PJ's.
Brilliant, very nice idle. (its got more power than that!)
Oh the mild scaling, love it, its been so long since my old mild engines (or any for that matter). It does not get the same effect on the inside (as im sure your aware) so it can look very bad for a long time before becoming a problem. Keeping the CRC/WD40 etc. up to them helps a lot too.

Really looking forward to you getting more fuel testing time on it. This should make a great deal of difference, and give us a better "feel" for the engine. (for those that don’t only use numbers ) The candid camera action also does wonders for bringing the action to us, so i don’t think that vids bad quality at all, very enjoyable. (again... not for the number crunchers )

Thanx for your vote of confidence in the plans, and good to hear that you used some of them.
I know cutting out paper patterns and sticky-taping everything all together is a right pain in the ass, but for this engine, its pretty light work compared to hand markout with any sort of minimum material wastage. And laying out eccentric cones by hand is not best on sheet steel!

There is only a few parts that are standard issue, so just print them people... took longer for me to set them out than you print them!

Good on you Grim, glad a big engine gave you a thrill.

Rossco

[Jamiepo]

Hey Grim, your build looks awsome!!! congrats .

Now, I am new to the whole world of pulsejets but the concept seems faily straight forward and with the patterns that are provided with it should be a fairly easy build. What I need to know is what did you use to roll the cylanders and cones? I have a roller at work but its minimum roll diameter is around 450mm so it is not really suitable for the job, if it comes down to it I can fab up a hand cranked roller jig but I was just wondering how you did it as all of your stuff came out really nice. I also need to know how pedantic I have to be about grinding down internal seams once thay have been welded, is it okay to leave a lttle bit of penetration or is it best to have one smooth surface? I will be using mild for my first build as it is cheaper, easier to roll and weld and we have a fair bit of scrap at work I can scavange.

Cheers,
Jamie

[GRIM]

Congrats on the run,

HI Rossco, THANK YOU SIR , and congratulations to you and M , you guys put more work into this than I did ,

Hi Jamie , welcome ,
I will post something about my cone forming technique over in tools n construction ,

As for excess penetration , the root welds need to be as smooth as possible on the inside, expect to have to do some grinding/sanding, especially in the critical areas , Combustion chamber / tailpipe transition for example ,

If this is to be your first pulsejet, I would recommend building one of the smaller engines first, there are a lot of things to learn about starting and running one of these, and it would be safer to "get the feel of things" on a smaller engine first ,

G

[Irvine.J]

Hi Grim,
Congrats on your test run.

When will you thrust test this? I see no issue with your current fueling rig, many engines employ injector centering brackets.
Why not just get out there and give us a max vapour reading?
Plenty of time for some liquid trials after that! ETA?

Eagerly awaiting your reply.
James.

[GRIM]

Hi James,

Congrats on your test run.

Thanks,

When will you thrust test this? I see no issue with your current fueling rig, many engines employ injector centering brackets.
Why not just get out there and give us a max vapour reading?
Plenty of time for some liquid trials after that! ETA?

I intend to try for maximum power on vapor , with the setup that I have , the ambient temperature is a factor , and I need to move on this soon , before the winter comes,

I am working on another potential test site ,( A quarry ) no animals, no neighbours, nothing to burn ,
But I need to fit a gasoline engine to my compressor , or buy a leaf blower , or hire a generator, there arent many remote places that have conveniently located electrical outlets , Unfortunately Time and Money are restricting factors for me,

will post as soon as I have some news ,

G

[GRIM]

MAYBE

Opinions?

[Mike Everman]

Looks neat! As to blower, I just got a Black and Decker 12v cordless leaf blower. Light and powerful.

[Mike Everman]

OK, wait a second, I just noticed you're planning on being tucked in above the motor? Scaaaary. I thought that whale tail up above was the seat!

[GRIM]

I am thinking full length, double skinned aluminium / rockwool half round heat shield, between the motor and Pilot
and yes I doubt that the DUMMIE , would be smiling much,

[larry cottrill]

Yes -- that is scary, but I'm thinking especially of the head-first orientation. Please re-think this, sir.

I don't think the engine beneath is so bad, though. I just think your shield would need to be larger coverage and pretty nearly seamless -- remember it has to be not only a heat shield but a firewall as well. Maybe with fibre insulation that would be covered all right, I'm not sure.

L Cottrill

[Jutte]

It's always a better idea to have feet first - broken legs tend to heal better than a broken
head. Also being enclosed in the frame like that is a possible trap situation -
if during a crash/roll over the frame gets bent you're stuck with a red hot motor
and fuel tank inches away from you.
Try thinking about adapting a go-cart type of frame.I have had a little experience
with racing karts - the seat will hold you in fine - but you can still get up and
gap it if it decides to go up in flames.
That's why I went for a scooter - the whole dump it and run away like crazy thing
if it all went to custard....LOL! ( run away run away !!!)
Oh yeah... better have good ear plugs with your helmet !

[metiz]

Oh yeah... better have good ear plugs with your helmet !

Or have realy strong earmuffs to compensate for the lack of a helmet

[Graham C. Williams]

Well Done! Good design and a great build.
Grim, M. and Rossco. What a team!!

Hmm, I'm not so sure about the cart design. I've been close to a running Lockwood and can only imagine this motor is no more comfortable to be near. It was one of Rossco's fellow countrymen (Gary)that likened it to "Wanting a Piss and a Pint at the same time"; nothing if not direct the Aussies. Ha
Still, lovely to see the video of it running in such an open manner.
I'd love to see what happens if you fuelled it with a pair of Collins Collars

Keep up the good work
Graham.