PREDATOR - valveless PDE build blog

[Viv]

Very impressive work, well done

Viv

[zono]

thanks, Viv !

Next time I will add some effects to visualize the run parameters. First show effect will visualize the exhaust impulse (damage of a sheet of paper, push-away a paper bin....) . For measurements I will construct a impulse-pendulum to indicate the impulse ( impulse conservation law : m1 v1 = m2 v2) to confirm 1800 m/s exhaust velocity (or whatever it indicates).

Next step is an improved injection and ignition control by Atmega169. Programming is done already, but my #@!?*$&§ Power-Mosfets do need 15V gate voltage, and the Atmega only provides 3,3V. ...Looking for a 15V line buffer (line driver).

zono

[Viv]

Hi Zono.

Ok That's all good, for the Mosfets you can try a standard opto-isolator, that will keep your logic devices safe on one side and you can simply power the other side with what ever gate voltage you want.

Pendulum thrust stands are a good choice but watch how you read it and calculate your results, it can be tricky to get a truthful reading as others have demonstrated in the past.

As I said good work, I enjoyed following your test

Viv

[metiz]

Guess I have to eat my hat realy nice work!

With the right software and hardware in place, what kind of detonation frequency do you hope to achieve?

[zono]

@metiz:
I think 1...2 Hz. Filling is the bottleneck.

@Viv:
thanks, opto-coupling is expensive, but you are right! Best for safety.

zono

[PyroJoe]

Good work!
Nice to see one put together.

[Viv]

@metiz:
I think 1...2 Hz. Filling is the bottleneck.

@Viv:
thanks, opto-coupling is expensive, but you are right! Best for safety.

zono

Hi Zono

Sorry expensive? are talking about the same thing, should be cheap as chips.

http://en.wikipedia.org/wiki/Opto-isolator
http://www.electronicrepairguide.com/optocoupler.html

Viv

[zono]

hmmm right Viv, I found some opto for less than 1$ .....lets try transistor-optos and triac-optos

zono

[Viv]

hmmm right Viv, I found some opto for less than 1$ .....lets try transistor-optos and triac-optos

zono

Hi Zono

Keep it simple and go for the transistor ones as it will be easier for you to interface than the triac versions (better for high power operation in PSU)

Viv

[zono]

See some details of the test rig:

spark plug, gas injector and solenoid valve

zono

[zono]

Hi friends,

new runs of Predator were done on DOT (Days of speed and Thunder, big pulsejet meeting in Rothenburg, Germany at 17.-19. May 2012, http://www.pulsotriebwerk.de).

As announced before, I tested MCU controlled gas injection and ignition - with great success!

Now I am posting the first images. More come in the next days...

PS: the supports were rammed into the soil due to the detonation impulses

[zono]

and here are the vids:

http://www.youtube.com/watch?v=Nn9I1RXT0TM&feature=plcp

http://www.youtube.com/watch?v=TYLmpxKcnDM&feature=plcp

Detonation shockwaves had awsome intensity. They destroyed parts of my test rig (momentum gauge)

[zono]

hmmmm

nobody left in the PDE forum? Nobody interested any more? Not even defense industry

have a look above. New runs done in May 2012.

[metiz]

Will your engines ever be able to run continiously?

[Mike Everman]

Oh, definitely still interested!