Mike's Build Log

Moderator: Mike Everman

Sebastian LFT
Posts: 57
Joined: Mon Aug 25, 2008 5:50 pm

Re: Mike's Build Log

Post by Sebastian LFT » Wed Apr 15, 2009 1:16 pm

Ahkinxe tentay nemukem kenchimokan!! (most excellent fire pulse horn!!)
You'll never know 'till you try it.

Kool
Posts: 115
Joined: Wed Oct 01, 2008 7:39 pm
Antipspambot question: 125
Location: The Netherlands

Re: Mike's Build Log

Post by Kool » Wed Apr 15, 2009 1:30 pm

Wow, that one looks very amazing 8)
I am looking forward to the results
...It's better to generate heat efficiently, than recover it efficiently...

Mike Everman
Posts: 4931
Joined: Fri Oct 31, 2003 7:25 am
Antipspambot question: 0
Location: santa barbara, CA
Contact:

Re: Mike's Build Log

Post by Mike Everman » Wed Apr 15, 2009 1:33 pm

Thanks, guys! Yeah, M., I'm trying to step up my build log detail. I've been inspired by Ash's build log, and some of the ones over at the GTBA.

If I finish it up this morning before work, I can hopefully make a test run this afternoon. Much to do before I leave, though.

Nick's got a site for us to run motors in the vicinity of Gloucestershire on Monday. Anyone that wants to come, please PM me and I'll send a google earth location.
Mike
__________________________
Follow my technical science blog at: http://mikeeverman.com/
Get alerts for the above on twitter at: http://twitter.com/mikeeverman

Johansson
Posts: 1161
Joined: Sun Nov 21, 2004 9:42 pm
Antipspambot question: 0
Location: Northern Sweden

Re: Mike's Build Log

Post by Johansson » Wed Apr 15, 2009 4:29 pm

That is the best looking engine I´ve ever seen, it is almost a shame to run it. Some polishing and clear paint and it would make a nice bookshelf sculpture.

Just kidding, can´t wait to see how it runs! :D

Mike Everman
Posts: 4931
Joined: Fri Oct 31, 2003 7:25 am
Antipspambot question: 0
Location: santa barbara, CA
Contact:

Re: Mike's Build Log

Post by Mike Everman » Wed Apr 15, 2009 5:27 pm

Thanks, Anders.
I got the fuel and spark plug on it. It's ready for test this afternoon. Couple of places the TIG guy couldn't get at, so I had to hamburger it with my torch. Still looks good though. I can't wait for running it either. 6 hours and counting...
Mike
__________________________
Follow my technical science blog at: http://mikeeverman.com/
Get alerts for the above on twitter at: http://twitter.com/mikeeverman

Mike Everman
Posts: 4931
Joined: Fri Oct 31, 2003 7:25 am
Antipspambot question: 0
Location: santa barbara, CA
Contact:

Re: Mike's Build Log

Post by Mike Everman » Thu Apr 16, 2009 5:00 am

She runs orange hot!
...but when I went out with 30 minutes available to run it before going to the UK, all I had were empty tanks! One was up to a couple runs, but I sure couldn't get it over fueled. You'll like this vid. I did not notice the clamp undoing itself!
Attachments

[The extension wmv has been deactivated and can no longer be displayed.]

Mike
__________________________
Follow my technical science blog at: http://mikeeverman.com/
Get alerts for the above on twitter at: http://twitter.com/mikeeverman

Mike Everman
Posts: 4931
Joined: Fri Oct 31, 2003 7:25 am
Antipspambot question: 0
Location: santa barbara, CA
Contact:

Re: Mike's Build Log

Post by Mike Everman » Thu Apr 16, 2009 5:09 am

Run 2 with thrust gage, you can see it crest to 5.9 lb then plummet on low fuel. 270 Hz, exactly like it's 1/3 parent!
Video notes:
The color was not yellow like that to my eye. Something with my camera. It was orange all over. Still learning the settings on this thing.
Likewise the autofocus is screwy for the movie. don't know why, but I'm going to figure out how to switch it to manual at least.
Attachments

[The extension wmv has been deactivated and can no longer be displayed.]

Mike
__________________________
Follow my technical science blog at: http://mikeeverman.com/
Get alerts for the above on twitter at: http://twitter.com/mikeeverman

Johansson
Posts: 1161
Joined: Sun Nov 21, 2004 9:42 pm
Antipspambot question: 0
Location: Northern Sweden

Re: Mike's Build Log

Post by Johansson » Thu Apr 16, 2009 5:35 am

Great work Mike!

It ran colder on the right exhaust in the last video, was it because the engine was tilted somewhat?

Irvine.J
Posts: 1063
Joined: Mon Jun 05, 2006 4:28 pm
Antipspambot question: 0
Location: Brisbane, Australia
Contact:

Re: Mike's Build Log

Post by Irvine.J » Thu Apr 16, 2009 8:16 am

Absolutely wonderful Mike! Yes the far engine does seem to run a little cooler, I think its due to his near empty tanks more then anything though. Wasn't much coming out the exhausts yet so I will be surprised if he doesn't near double that 5.9 figure. Wonderful work Mike, she's an absolute beauty. Starts easy too!
If you can find something to give it a really dark (black sheet) background will help see those tail plumes easier, I think your on a winner.
James- Image KEEPING IT REAL SINCE 1982
http://pulseairdefence.com
[url=callto://project42labs]Image[/url]

milisavljevic
Posts: 855
Joined: Sat Oct 04, 2003 9:36 am
Antipspambot question: 125

Congratulations, Mike!

Post by milisavljevic » Thu Apr 16, 2009 12:30 pm

.
:D Congratulations, Mike! :D
Mike Everman wrote:You can see it crest to 5.9 lb.
I phoned Mike yesterday afternoon, moments after he concluded the test runs of his 3x pocket jet.
When he first mentioned his thrust measurement (above), I was surprised: like many folks here, I
naively assumed that this beautiful piece of work would punch out 3x the thrust of the original jet.

Then I remembered that multiple branches scale down in the general pulsejet equation: a 3-in-1 is
not the same as 3 equal copies, and 10.5 lbf of thrust (46.5 N) was never in the cards for this unit.

I offered to suss it out and to report back my results. Later that evening I left Mike voice mail and
told him that the simplest interpretation of the 3x combustor would peg maximum thrust between
6.0-6.1 lbf (27 N). I also said my result was probably an underestimate and that I would look closer.

As of this writing, I stand by a range of 6.0-6.1 lbf as the most probable thrust ceiling; however, I
offer an alternative Cronje limited evaluation that raises the ceiling to between 6.7-6.9 lbf (30 N).

I hope that Mike is able to settle this while visiting with Graham and Nick.*

Mike Everman wrote:[It resonates at] 270 Hz, exactly like it's 1/3 parent!
As Mike will know from many previous conversations, this is no surprise. As the 3x pocket jet is a
near-perfect bidirectional trifurcation of his original pocket jet, the special Helmholtz equation for
pulsejets will yield the same resonance frequency. Thank you Mike, for being the one to validate it!


With respect to the observations of asymmetric heating in the combustor:

As far as the three pairs of intakes and exhausts go, they are not equals: the central pair services
ca. 25-30% more volume than either side pair and consequently develops more thrust. This is over
enforced by Cronje saturation of the side pairs (ie., decreasing combustor radius in the y-z plane).

This does not discount the stack effect stemming from the orientation of the pulsejet on its stand.


This is a foundation piece of work by Mike and in my mind a major contribution to the community.
Thanks Mike, and I wish you a safe, productive and enjoyable trip to ol' Blighty! Have a warm pint. :D

Cheers,
M.

*The higher thrust range is the more (technically) interesting result.
no safe haven for merchant scum


for ye merchants who do the prop'r t'ing only if
ye be haul'd-up on charges b'fore ye ship-mates
an' threat'nd wit' forfeiture of all ye precious loot
hear this - so-called stand-up guys YE BE NOT

avast!
Cap'n M.

Mark
Posts: 10771
Joined: Sat Oct 11, 2003 10:14 pm

Re: Mike's Build Log

Post by Mark » Thu Apr 16, 2009 12:53 pm

I wonder if you made an engine with say eight tubes, same single chamber and all, if it would tend to flip-flop/recognize the oval combustion chamber in a different light? That is, would it attempt to delegate one side/end to more intaking and the far side to exhausting rather than working as a straight cluster all going uniformly? Funny how that one exhaust decided to let the other two fire off more of the activity.
I think one thing about odd shapes like ovals is that the combustion can be more erratic or the variation in reflective surfaces allows for more variables than the typical confined symmetry of a cylinder. Neat stuff and happy Zamfiring. ha
Presentation is Everything

larry cottrill
Posts: 4140
Joined: Sun Oct 05, 2003 1:17 am
Antipspambot question: 0
Location: Mingo, Iowa USA
Contact:

Re: Mike's Build Log

Post by larry cottrill » Thu Apr 16, 2009 1:14 pm

CONGRATULATIONS! Seems like I'm always "amazed" by something or other, but this is certainly a worthy beast to be amazed by.

M -
Very interesting observations about the layout, and its effects on flow distribution and power. I would have guessed that the overall behavior would bring about the same frequency (since Mike was very careful about the dimensions), but I would never have suspected such predominance of the center, in terms of flow and combustion action.

L Cottrill

PyroJoe
Posts: 1743
Joined: Wed Aug 29, 2007 5:44 pm
Antipspambot question: 125
Location: Texas

Re: Mike's Build Log

Post by PyroJoe » Thu Apr 16, 2009 1:31 pm

Great Work!
I would like to see this thing run on a full, peppy fresh tank. Man, what a engine. I have a hunch that the lower cylinder would glow more evenly if the motor were mounted more horizontal. Strange how the flame will migrate to the highest point in many engine CCs, not sure if thats is happening with this one but it looks it.
Joe

Mike Everman
Posts: 4931
Joined: Fri Oct 31, 2003 7:25 am
Antipspambot question: 0
Location: santa barbara, CA
Contact:

Re: Mike's Build Log

Post by Mike Everman » Thu Apr 16, 2009 1:59 pm

Thanks all, guys!
Yeah, I think it's just convection. I need a better hold down method, but was in a hurry!
Mike
__________________________
Follow my technical science blog at: http://mikeeverman.com/
Get alerts for the above on twitter at: http://twitter.com/mikeeverman

m1tch
Posts: 28
Joined: Tue Aug 25, 2009 11:05 pm
Antipspambot question: 125

Re: Mike's Build Log

Post by m1tch » Wed Aug 26, 2009 9:15 pm

Thats a really amazing build, just read this thread though from the beginning and its amazing to see the evolution! Well done mate!! Makes me want to try and make one lol

Post Reply