Blended bodies

[metiz]

Ok this is the engine twice as fat, surface wise. The choke angle is at 40 degrees. The top engine is what I think would work better. Choke angle at 49.1 degrees with longer cc and rectifier

[PyroJoe]

that looks good!
I like the shorter CC in the second one as its closer to 4 calibers in length. The longer tail on the first one looks close, maybe around 18 calibers in length. How do you plan on installing the 4 original intakes? At 0,90,180, and 270 degrees?

[metiz]

Hey Joe

I'm not sure if the short cc version will work for this engine. I just think the choke cone is to shallow. I'd like to give this engine a go but I'm still "working" (i.e. can't find the motivation to finish it) on a m40 with some plenums for petrol injection. After that I'd like to build a number of identical small/medium linear engines to try out a couple of other liquid injection methods I thought of. I'll see if I can get M to run this engine through is model and see if it's any good. I don't realy want to build an engine this size without knowing it will run/ perform or without a good way to fuel it. As for the intakes, I could go 90 degrees OR I could put them at 37.5, 142.5, 217.5 and 322.5 degrees.

[PyroJoe]

Looks like you have an understanding of the concept, that in itself is a good thing. These are just general guidelines anyhow. If there is something that looks to long or short, adapt it to fit what works for you. Keep an eye for what works. After all, there is probably no particular pj model or theory universal enough to be a law.

M boycotted/banned this forum, he is not on my favorites list at the moment. If I would have taken the path he has, you would not be reading this topic.

I wish you the best and continue to share your work.

[metiz]

You're not the only person to not get along with M. However, I don't have any problems with him. Regardless, one can't deny he's pretty much the most knowledgable person of pulse-jet engines out there.

His decision to leave the forum is his own. I may not agree with his motivation but so be it. I do appreciate you still actively posting your idea's and experiments; you are one of very few still remaining.

[PyroJoe]

The most knowledgeable ones have most likely passed on or are growing fewer in number.

There will be occasional conflict as the forum is made up of rugged individualists, nearly to the man.

Butt hurt medicine should be applied copiously all around. Those who liberally "suffer no fools" will eventually become the biggest fool in a world of fools.

[ganuganu]

k here is a simple design which i made...according to your plan if i make the engine as shown in the fig will it work..

[PyroJoe]

the two intakes look good, but the Combustion chamber diameter and tail diameter have been doubled in diameter, instead of area.

[ganuganu]

iam sorry i didnt read the picture properly before..k now here is the design will this work..

[PyroJoe]

Almost there, the intakes should be left seperated, basically two blended bodies EXCEPT for the intakes.
Good work on calculating those areas of the tail and chamber

The difficult part of blending is if there is a small problem with the single engine, it becomes twice as much a problem after they are blended.

[ganuganu]

there was no problem with my single engine..so iam going to try this..will this increase the thrust produced by the engine???

[Kool]

No, one big intake is the best for increasing thrust, also augmenting with one intake is a lot simpler.

I think I don't really understand it, but when you double up the engine ( in area of course), you could use the same intake twice, or not?
This it what Pyroyoe seems to do. Because developing of one bigger inlet is not only in area, but also in length, which has to be tested ed.

[Mike Everman]

No, one big intake is the best for increasing thrust, also augmenting with one intake is a lot simpler.

I think I don't really understand it, but when you double up the engine ( in area of course), you could use the same intake twice, or not?
This it what Pyroyoe seems to do. Because developing of one bigger inlet is not only in area, but also in length, which has to be tested ed.

Absolutely right, a single intake for this would change the whole design. An intake gets squirrely at less than about 3.5 Length/Diameter. Not that it wouldn't work, as this format is very forgiving of bad geometry.
Thrust increase is most likely about 40% more instead of 2x at a guess. I'm considering building a 2x pocket jet to test that theory, since I've already got numbers for the 3x.

[ganuganu]

what do you think about this design blending of two 7.87" dia cc..here is the pic..

[PyroJoe]

Here is what I show:
(Assuming 4 intakes)
cm [inches]