Mike's Build Log
Moderator: Mike Everman
Re: Mike's Build Log
Hey Mike, looking good! (and the engine to; har har)
I've not been following this thread for some time and you might have mentioned this before, but why don't you try an expanding tailpipe for some more thrust with (don't know how thick that tailpipe is) almost no (if any) aditional weight?
I've not been following this thread for some time and you might have mentioned this before, but why don't you try an expanding tailpipe for some more thrust with (don't know how thick that tailpipe is) almost no (if any) aditional weight?
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Re: Mike's Build Log
Why, indeed! For what I want to do, I want the highest gas speed and hottest exhaust. I'm close enough to my goal with this one, now I can take the next step (and it's not an expansive tail
Here's the video.
http://www.pulse-jets.com/pocket%20jet2x1.2%205meg.wmv
Here's the video.
http://www.pulse-jets.com/pocket%20jet2x1.2%205meg.wmv
Mike Often wrong, never unsure.
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Re: Mike's Build Log
Here's a vid of the test stand bearing and the first fuel up, without thrust gage, just getting the feel of it. Quite an easy starter. I think a fixed Rossco would make a good air free start.
http://www.pulse-jets.com/mikesbuilds/p ... earing.wmv
http://www.pulse-jets.com/mikesbuilds/p ... earing.wmv
Mike Often wrong, never unsure.
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Re: Mike's Build Log
Hmm revamping the tailpipe into one with an integrated augmenter?Mike Everman wrote:I want the highest gas speed and hottest exhaust. (and it's not an expansive tail
http://www.pulse-jets.com/pocket%20jet2x1.2%205meg.wmv
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Re: Mike's Build Log
Geat engine , excellent videos,
5.4Lb from only 0.9 liter Wow , and the strain gauge is impressive too ,
Well done Mike
G
5.4Lb from only 0.9 liter Wow , and the strain gauge is impressive too ,
Well done Mike
G
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Re: Mike's Build Log
Yep, and also a free power turbine, and also a whirly motor.metiz wrote:
Hmm revamping the tailpipe into one with an integrated augmenter?
Thanks guys. I'm really stoked about this one.
Mike Often wrong, never unsure.
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Re: Mike's Build Log
Mike:Mike Everman wrote:Yep, and also a free power turbine, and also a whirly motor.metiz wrote:
Hmm revamping the tailpipe into one with an integrated augmenter?
Nice job!!
Looks like you could augment both ends.
Bill
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Re: Mike's Build Log
Yep. After a little detour, I'm going to build both conventional augmenters and a new type "to be named later". I'm torn right now between super augmenters and shaft power. I'm about to make a 3x pocket jet, 3 intakes, 3 exhausts, common elliptical cc, which will be my 1.5L entry. That will be of interest to you, Bill, as it will test the notion that all length and areal numbers times three will get me 3x thrust, which would push 10 lb hopefully. I'm sure that the 3 intakes with 3x duct areas and a single exhaust does not follow this reasoning, and must be longer.
I'll post the rendering when I get back to my project computer.
Edit: I meant all areas tripled, all lengths the same.
I'll post the rendering when I get back to my project computer.
Edit: I meant all areas tripled, all lengths the same.
Mike Often wrong, never unsure.
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Re: Mike's Build Log
Here's the triple. I think I want to bump up the intake dia, considering how well the upscale went at a little higher confinement ratio.
Mike Often wrong, never unsure.
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Re: Mike's Build Log
SUH-WEET!!!
Something is curiously "automotivey" about this design...
Cheers!
M.
Something is curiously "automotivey" about this design...
Cheers!
M.
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Re: Mike's Build Log
Dear Mike.
What a lovely little motor (>5Lbs) Well done!
Ref the lower thrust value. It is a possible that the motor is producing negative thrust (Positive thrust but in the other direction) at your lowest fuel settings, it's easy enough to check. What impresses me is the resonate combustion at these low fuel settings.
So how are you going to get this motor up to 30+ N/L? Ha.
Great work - Lovely motor.
Graham.
What a lovely little motor (>5Lbs) Well done!
Ref the lower thrust value. It is a possible that the motor is producing negative thrust (Positive thrust but in the other direction) at your lowest fuel settings, it's easy enough to check. What impresses me is the resonate combustion at these low fuel settings.
So how are you going to get this motor up to 30+ N/L? Ha.
Great work - Lovely motor.
Graham.
Dark days nurture new
light. Productions begin.
Now open your eyes.
light. Productions begin.
Now open your eyes.
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Re: Mike's Build Log
thanks guys,
Yeah, Graham, the zero reading makes me want a more rigid link to the loadcell to see if it actually goes negative. Doesn't seem possible. Intake exhaust at that low setting is positively cold!
Yeah, Graham, the zero reading makes me want a more rigid link to the loadcell to see if it actually goes negative. Doesn't seem possible. Intake exhaust at that low setting is positively cold!
Mike Often wrong, never unsure.
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Re: Mike's Build Log
Hello Graham (and Mike!) --
As a duct is throttled down, its forward pressure ratio (and similarly, thrust split) declines to a limiting value of 1.*
It is entirely possible (and for deep-throttled poket-jet style ducts, near certain) the net intake thrust is negative.
This said, the overall net thrust must remain positive or zero, if the duct is in equilibrium under static conditions.
Boundary layers may absorb enough momentum to result in net nil thrust, but the boundary layers work both ways.
volume-specific thrust density moves inversely with thrust class: "The bigger the cushion, the thinner the pushin'!"
Cheers,
M.
*To eliminate any possible ambiguity, the pressure ratio goes to 1; net thrust split (as a ratio) goes to 0.
You know how timid I am when it comes to interjecting maths (or facts) into any discussion of pulsed combustion!Graham C. Williams wrote: It is a possible that the motor is producing negative thrust [snip] at your lowest fuel settings[?]
As a duct is throttled down, its forward pressure ratio (and similarly, thrust split) declines to a limiting value of 1.*
It is entirely possible (and for deep-throttled poket-jet style ducts, near certain) the net intake thrust is negative.
This said, the overall net thrust must remain positive or zero, if the duct is in equilibrium under static conditions.
Boundary layers may absorb enough momentum to result in net nil thrust, but the boundary layers work both ways.
I know that you're simply teasing Mike, and that this small a duct can easily surpass 30 N/liter, but you also knowGraham C. Williams wrote: How are you going to get this motor up to 30+ N/L?
volume-specific thrust density moves inversely with thrust class: "The bigger the cushion, the thinner the pushin'!"
Cheers,
M.
*To eliminate any possible ambiguity, the pressure ratio goes to 1; net thrust split (as a ratio) goes to 0.
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.
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.
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Re: Mike's Build Log
Some progress on how it's going to go.
Mike Often wrong, never unsure.
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Re: Mike's Build Log
one more. just having fun with the renderer.
Mike Often wrong, never unsure.
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