concentric lockwood

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sockmonkey
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Re: concentric lockwood

Post by sockmonkey » Sun Jun 24, 2012 7:06 pm

I wonder if I'm going about this backwards. We've all heard of mishaps where an engine or gun or something has experienced an unexpected choking or blowback. Maybe some pre-existing structure can be copied and made to do so on purpose. I've seen a few cutaways of gun silencers that make me think "Hey that looks like a tesla conduit." So it could be that others have already done the homework and we could crib something off of that.

sockmonkey
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Re: concentric lockwood

Post by sockmonkey » Sun Dec 15, 2013 5:22 am

hagent wrote:
sockmonkey wrote:Hmm, how about this?
Image
I like it. Thermal distortion won't be a problem on the intake, since the intake does not get that hot.
The pointy part where the intake comes into the CC area may need to be looked at. If you build this you may want to put a flat area there. This might help with the sound/pressure reflection back down the exhaust, which I think would be benificial, but you won't know unless you try it.

Hagen
If I were following the Schubert or Escopette configuration I would add a flat spot but I'm basing it on the Lockwood since that one gives a good performance and apparently doesn't care if it has weird bends as long as the diameter is right.
This image should show what I'm trying to do.
Image
As you can see, It's just a Lockwood straightened out. It's pretty darn long but the frontal area is smaller than a bent Lockwood and the end cap/thrust deflector has a nice aerodynamic shape. I Don't think an augmenter would work on both ends since the rear one would be re-ingesting hot gas from the front exhaust/intake.
I did add a bit of a shrouding along the length to make more aerodynamic overall and to act as bracing since it's so long. The shrouding will of course have vent holes in it to keep it from trapping so much heat the thing distorts.
I think by moving the deflector all the way to the end of the intake pipe it won't screw up the rest of the cycle since that's where the intake has a little flare anyhow, but I am worried about the sharpness of the curve choking the thing though.

metiz
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Re: concentric lockwood

Post by metiz » Sun Dec 15, 2013 8:22 am

Are you planning on flying that lockwood? If so, you might want to consider a Chinese style engine. They're powerfull and straight. Try my M40 for example, 40+ pounds of thrust and only 1.5m long
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sockmonkey
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Re: concentric lockwood

Post by sockmonkey » Sun Dec 15, 2013 9:36 pm

I was under the impression that Lockwoods are one of the better valveless ones in terms of efficiency and power to weight ratio.

metiz
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Re: concentric lockwood

Post by metiz » Mon Dec 16, 2013 9:35 pm

sockmonkey wrote:I was under the impression that Lockwoods are one of the better valveless ones in terms of efficiency and power to weight ratio.
HAHA! oh hell no :lol: more on the opposite side of the spectrum
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Mark
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Re: concentric lockwood

Post by Mark » Tue Dec 17, 2013 1:21 am

I bought some literature from Lockwood Jr. a long time ago where he had photos of a twin arrangement with 4 augmenters where each engine made 150 pounds of thrust. Together the twin engines with augmentation weighed 30 pounds and were said to produce 300 pounds of military max. thrust, 280 continuous. They used fiberglass reinforced plastic for augmenters because the exhaust heat was low enough to get away with a plastic I guess. Each engine had a 10 to 1 thrust to weight ratio. His augmenters were very short, the unit looking about a foot high with four holes in the molded(?) square shaped augmenter cluster. Interesting idle speed of 30 pounds thrust. It looks like it would have a lot of drag at high speeds. ha

Here's the same literature with augmenter cluster (See Model HH 5.25-7 Basic Specifications)
http://rocketbelts.americanrocketman.com/pulse.html
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sockmonkey
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Re: concentric lockwood

Post by sockmonkey » Tue Dec 17, 2013 2:20 am

metiz wrote:
sockmonkey wrote:I was under the impression that Lockwoods are one of the better valveless ones in terms of efficiency and power to weight ratio.
HAHA! oh hell no :lol: more on the opposite side of the spectrum
I am woefully misinformed. I was under the impression that it had been tweaked a bit more than most. So how do the other designs rate?
Mark wrote:I bought some literature from Lockwood Jr. a long time ago where he had photos of a twin arrangement with 4 augmenters where each engine made 150 pounds of thrust. Together the twin engines with augmentation weighed 30 pounds and were said to produce 300 pounds of military max. thrust, 280 continuous. They used fiberglass reinforced plastic for augmenters because the exhaust heat was low enough to get away with a plastic I guess. Each engine had a 10 to 1 thrust to weight ratio. His augmenters were very short, the unit looking about a foot high with four holes in the molded(?) square shaped augmenter cluster. Interesting idle speed of 30 pounds thrust. It looks like it would have a lot of drag at high speeds. ha

Here's the same literature with augmenter cluster (See Model HH 5.25-7 Basic Specifications)
http://rocketbelts.americanrocketman.com/pulse.html
Dang that's awesome.

I've been puttering around on this forum for years and read a lot of what people have said and looked over all the posted articles but I guess I'm still barely scratching the surface. Someday I think someone with access to a proper supercomputer is gonna come up with a configuration that can match turbojet efficiency.

metiz
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Re: concentric lockwood

Post by metiz » Tue Dec 17, 2013 8:46 pm

A pulse-jet is already more efficient than a turbojet. A properly build pulse-jet with augmenters ($10) can outperform a mini-turbojet (~2500$)

*edit* and that's with continuous injection instead of timed. I've read somewhere (can't remember the source, Mark, do you know?) that a properly timed fuel injection system can increase efficiency 7 fold in a perfect world. In reality, a 3-4 fold increase is more realistic
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Re: concentric lockwood

Post by Mark » Tue Dec 17, 2013 9:50 pm

I never delved into valveless pulse jets that much but I recall reading a few accounts of timed fuel injection. Too bad the big corporations didn't/don't publish their old pulse jet findings in deep detail for all to read.
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sockmonkey
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Re: concentric lockwood

Post by sockmonkey » Wed Dec 18, 2013 1:09 am

metiz wrote:A pulse-jet is already more efficient than a turbojet. A properly build pulse-jet with augmenters ($10) can outperform a mini-turbojet (~2500$)

*edit* and that's with continuous injection instead of timed. I've read somewhere (can't remember the source, Mark, do you know?) that a properly timed fuel injection system can increase efficiency 7 fold in a perfect world. In reality, a 3-4 fold increase is more realistic
You mean in terms of power-to weight ratio yes? It was my understanding that they weren't as good in terms of fuel efficiency. If they were, then the only thing holding them back would be the noise and we would see them used more.

sockmonkey
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Re: concentric lockwood

Post by sockmonkey » Fri Jan 03, 2014 1:47 am

With my last iteration I realized I was basically doing something almost identical to the Messerschmitt design for a pulsejet that transitions to a ramjet at high speed. I'm not trying to duplicate that effect though.
One thing I did a little different is having the front cone taper in a bit at the back to direct more air into the intake during the inhale.

Here I tried going in another direction with it by adding a tube running the length of it that slowly increases in diameter that might potentially act as a ramjet itself.
Image
Since the air in the center tube runs the length of the whole thing it should have plenty of time to absorb enough heat to produce at least some small amount of thrust.

sockmonkey
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Re: concentric lockwood

Post by sockmonkey » Sun Jan 12, 2014 2:35 am

This is another idea that came to me. Bouncing the exhaust blast from the intake back into the main chamber right after the inhale to compress the fresh charge between that and the returning main exhaust for more efficient combustion.
Here is a crude diagram of how the cycle would work.
Image

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