42Labs/Cotrill FWE Hyperpulse MK I

Irvine.J · Post by **Irvine.J** » Mon Mar 12, 2007 3:19 pm

The story:
It's now midnight... a humid fog hangs in the air... Exhausted and excited, I return to my computer to post this message...
As you know I have built several engines of the Lady Anne varients with limited success, one of four managed to achieve sustainable operation though fueling issues remained present on the single intake model....I knew the design was promising, Heck I'd seen its potential first hand, I knew that many members of the forum had contributed a great deal to it... And I didn't want to let anyone down, my legs were shaking with nervous tension.

I had a huge learning curve recently with nudis and experimented and visualised pressure and massflow waves as best I could.... I designed on paper a modification for the Lady Anne Mk VII, and decided to go ahead and build it changing the intake, an extension and tailpipe. The nudis models looked promising, but as my first "Theoretical" design modification I wasn't too hopeful... I had to keep it shorter then the chinese, but give more power... no easy feat... if it even ran...

I nervously threw on my earmuffs, charged the compressor, and stuck the fuel line into the intake, no pinch, just a straight tube... the Tension was incredible...

The Fuel/air mix spewed forth into the CC in enveloping symphony of bangs.... then a roar... then another roar.... BBBBBBBBRRRRRRRRAAAAAAAAAAGGGGGGGGG
HHHHHHHGGGGGGGGHHHHHHHGGGGGGHHHHH

IT WORKED!!!!! "&%#@"!!!! I YELLED TO NO EVAIL OVER THE ROAR OF THE ENGINE!!!

It throttled extremely well, and still 4 to 5 inches shorter then the chinese...BUT DOES IT HAVE THE POWER!!! It definantly has the throttle range... 2 videos, one with tip intake and one with deep intake... deep intake sounds great.

Well what say you all?! Who's up for a thrust test I don't know If I can get it happening fast enough here? To all those involved I hope this appeals to you...
So now let me introduce...
The 42Labs/Cotrill FWE Hyperpulse MK I -Hyperpulse part subject to namechange.

larry cottrill · Post by **larry cottrill** » Mon Mar 12, 2007 7:40 pm

James -

Sounds good - but I won't be able to view the video files until I get home and have time to have a look tonight (a few things to do before then!). I'll check back in sometime after I've seen her run.

Nice going!

L Cottrill

Jim Berquist · Post by **Jim Berquist** » Mon Mar 12, 2007 11:14 pm

I was unable to view your fist video, It just came up with weird symbols.

The second one ran fine???????

Engine rocked and was spiting power out both ends......

Jim

Irvine.J · Post by **Irvine.J** » Tue Mar 13, 2007 12:35 am

Make sure you right click and save target as, not just click on it. Its a mov you'll need to download first. Enjoy

To all those involved...
James D, Graham, Larry, Nick, I am not fully aware of what part everyone played in the designing of this engine. I'd just like to commend you all for your good work, I may not of made myself clear when I said GOOD WORK! ( though I certainly tried)
All of you worked really hard, and Its great to see James' Mod and my mod running solidly. I look foward to any future developments. Next we will try the original MKVII with the 26mm intake.
Regards
James.

P.s: Graham, I'd like to commend you also in regards to Nudis, its an excellent program and I look foward to offering what limited information and suggestions I can. Right now it seems excellent as it is, though I might need a little help on data interpretation.

larry cottrill · Post by **larry cottrill** » Tue Mar 13, 2007 12:04 pm

James -

All right. Now I've seen it.

James, that is really impressive! It is kind of what Eric always wanted me to do: make a "Chinese" FWE. Well, I never got around to it, but you've done it. It certainly proves that the FWE chamber is capable of driving a BIG, massive tail piston! I agree that the heating of the pipe looks really good. I apologize for seeming so critical in my private communication to you and Graham - but then, you ended up not abandoning the FWE chamber after all ;-)

Sadly, I haven't done anything with the NUDiS files you sent except run the slider up and down a couple of times. I was immediately impressed with how this pipe refills - that's just the kind of action you want to see. I obviously haven't studied it enough to be exactly sure what the mid- and choke cones are doing in this configuration - but they certainly don't seem to be getting in the way ;-)

You could surely scale that up linearly all around and have a good contender for the Great 32-inch Chinese Valveless Pulsejet Engine Competition. It would not be a very high ratio scale-up, so I'm sure you could get a good runner without any fancy length/diam adjustments, though of course, you could "push" the diameters to a little higher ratio if desired. It would be interesting to see how far you could go with "fattening it up"! This would probably demand dual intakes if you took it very far.

Would you like me to try to come up with a "ramjet augmentor" design to retrofit on this pipe? Might be just a nice "finishing touch" ... I would need a simple non-scale drawing (or schedule) of the exact "as built" dimensions.

L Cottrill

Irvine.J · Post by **Irvine.J** » Tue Mar 13, 2007 4:26 pm

Now affectionately known as the Irvine/Cottril FWE HPX - MKI, its standing by ready for some thrust testing tomorrow. I've re-inforced the crude scale I have here and look foward to some tangible results tomorrow.
Wish me luck.

Thanks Larry for your post! It is really exciting to see it running so well.
I'm experimenting with tailpipe D's and lengths to try to eek out the most thrust I can, once I get some real data on its running performance we can discuss a good way to go from there. It might only be putting 1 lb of thrust so I'm a bit nervous about it, though if the nudis models are correct or if I am interpreting them correctly we might be in for a bit of a surprise (That's me being SUPER optimistic :)
Best of luck to all.
James

Ps: Graham, in Nudis, in the C Setup screen there are some yellow boxes with "Enter CC volume", "CC Diameter" and "CC length" in meters. Will Nudis automatically calculate that or do I need to enter those values? I put in the values when I was doing my initial calcs, the fuel CC cells, etc. The only thing I wasn't sure about with the FWE intake was the CC diameter which was set at .064 Meters.
Please Advise.
Thanks, James.

Jim Berquist · Post by **Jim Berquist** » Tue Mar 13, 2007 11:16 pm

Thank you !!!That worked and your engine still looked to be sending out power from both end........Good Stuff!!!

Jim

Irvine.J · Post by **Irvine.J** » Wed Mar 14, 2007 2:29 am

First thrust tests are complete.
Initial tests showed a max stable thrust of 1.65kg or 3.6lbs of thrust as is.
I am going to build an augmenter to see what the net gain we could possibly achieve from a properly tuned tailpipe.

As it stands though, its an excellent middle of the range engine between the FWE 2.25 and Chinese 4.5lb. Right between the 2 size wise also. 3.6lbs was achieved by a standard straight tube about 5cm into the intake. Experiments continue.

Graham C. Williams · Post by **Graham C. Williams** » Wed Mar 14, 2007 12:16 pm

Irvine.J wrote: Ps: Graham, in Nudis, in the C Setup screen there are some yellow boxes with "Enter CC volume", "CC Diameter" and "CC length" in meters. Will Nudis automatically calculate that or do I need to enter those values? I put in the values when I was doing my initial calcs, the fuel CC cells, etc. The only thing I wasn't sure about with the FWE intake was the CC diameter which was set at .064 Meters.
Please Advise.
Thanks, James.

Dear James.

This Public release does not use or calculates its own values for : CC volume and CC Length. So you donâ€™t need to do anything.

The â€˜FWEâ€™ CC diameter will be set to the default value of 0.064M. Iâ€™ve found a value of 0.05M to be better and used this value when looking at the VIII motors. The CC dia. directly affects the Total combustion time and so the way the motor reacts during combustion.

Graham.

Rossco · Post by **Rossco** » Wed Mar 14, 2007 12:30 pm

This is great stuff James I.

Thanx for having me over yesterday for the show of noise and fire.
Always fun sharing some of the exitement.
Much improvement in stability and throtleability. To the point of being a serious contender for that plane?!
By ear, eye and gut, its getting very close, just get to extracting that little extra now!

Very impressed with your theory work. Most of us here have been slogging away at that for a much longer time, getting a teneous grasp, then haveing it slip away as soon as we get cocky.
(you wait, an engine will come to you, theory too, it will be PERFECT! then in steel, it wont work any better than a toy wistle)

Keep going at it, theres more power to be extracted from the tail! Ill give you a hand with the augmentor tests when your ready. Literaly most likely, as long as im allowed a glove!
We shall goad some more out, till it respects our understanding of the theory!

Larry, augmentor yes, as a testing tool, not an otherwise unproven shroud concept.
Would you agree that testing an augmentor on the tail here will give an indication of extra energy in the exhast end to be had by tail tweeking?
By this i mean center chaimber too! Yes, i think this does need some serious overhauling to optimise. We need the best, or at least the best compromise of both worlds for James' project. Compact is one, although it does have to be a little reliable to boot!
(James, i dont know what people are going to start thinking about us? Nudi runs all night, and now tail tweeking!)

Graham, we are getting some very odd results at times from Nudis.
Especialy when the negative numbers turn up in the thrust calculations. This throws all data gathered over hours of running out the window! Often this has occured from the simplest of changes of a nicely running engine.

Rossco

Eric · Post by **Eric** » Wed Mar 14, 2007 3:04 pm

Very nice work James! With some tweaking you should get enough thrust for your plane, Im really excited to see how this layout performs with a full length chinese expansion.

Eric

larry cottrill · Post by **larry cottrill** » Wed Mar 14, 2007 3:50 pm

Rossco wrote:Larry, augmentor yes, as a testing tool, not an otherwise unproven shroud concept.

Why is an "unproven shroud concept" more of a minefield than an unproven engine design? We keep trying those, and they're only "unproven" until they're built and tested - why doesn't the same apply to a simple sheet metal cone?

Would you agree that testing an augmentor on the tail here will give an indication of extra energy in the exhast end to be had by tail tweeking?

Not necessarily - the problem is that a tail end that is entraining a lot of air already is going to make far less effective use of an augmentor. For one thing, the exit velocities are much lower than with a straight pipe. There is some experimental evidence (by others) that on a "bustle tailed" engine, augmentation of the rear-facing intake buys you more advantage for the material weight used. But, only by testing will you know for sure - so, blast away! All I would ask is, while you're playing with augmentors, see what a nice one behind the intake will do.

By this i mean center chamber too! Yes, i think this does need some serious overhauling to optimise.

Yes, that's part of what I was getting at in my private note to James - once you alter the layout by increasing the length and volume, the mid cone and choke cone are no longer optimally tuned for the rest of the engine. This could be the main reason you're currently under the 4 lb mark for stable thrust.

James, now that you have a good test stand set up (could you show us?), sometime try your "104mm mistake Lady" again and get us a good figure on that one, please. I'm just curious to see what we really have there, since that one at least sustained all right, apparently.

Also remember that IN FLIGHT, you will gradually starve the intake more and more as speed increases, meaning you will have richer and richer operation WITHOUT perceptible thrust increase. I think you should look at using a Melenric-style "cowl" around the intake rim. This is a tricky deal, and can only be perfected experimentally, I think. A cute trick would be to have a servo-driven "split shell" cowl that would close around the intake output stream as the throttle is opened, so it would try to linearize the air/fuel ratio (it would be streamlined to the flight direction in the "low throttle" position). The idea is to stall and slightly pressurize some air right around the intake flare at high speed. Without some kind of refinement like this, you could get rich extinction whenever you try to "push" throttling a little too far at speed, greatly reducing the ultimate flight performance of your engine. This is the "hidden" downside of using the rear-facing intake geometry on a flight engine - Melenric definitely had this on his designs for a reason!

L Cottrill

Rossco · Post by **Rossco** » Wed Mar 14, 2007 10:37 pm

Hi Larry,
I was tired and in somewhat of a rush when i wrote that, so i may have been a little unclear.

I agree that there is very little gain to be had on a megaphone tail with an augmentor. Funnily enough, this is exacly the reason that we wish to try it! Just as a quick test for energy there to be converted. There is some serious heat, and much velocity at that tail.

Now, I would like very much to see your idea of an optimised shroud augmentor for this engine, yes please. It is up to James whether it would altimately be used in flight if this ends up there.
Just hold of on puting the work into this for a while. Let us get this little beast under control first. One thing at a time... then I (probably we) would be happy to test your shroud augmentor. There is some serious v at the intake on all of these little FWE's.

I have always had every intention to put some sort of shrouded augmentor/passive ram jet on most of my engines, whether imaginary or real, although not one of them has got to that stage of tweeking and finalised complexity. I can't say that i have come up with any calculated geometry, although the idea makes sence and has been in the back of my mind since way back when we started talking of such things!

These "unproven" ideas are really moving along at a good rate now, and a lot are becoming proven ideas (one way or the other). I dont mean at all that if its unproven, then it wont work. (i wouldnt be here with that) Its just the engine is not ready for another unknown yet, hell its still a fair unknown itself!

Cya soon James... Wake up! its time to make some NOISE!
(we have planned a short run thismorning, followed by some serious theory lessons for both of us)

Rossco

Graham C. Williams · Post by **Graham C. Williams** » Thu Mar 15, 2007 1:08 am

Rossco wrote:Graham, we are getting some very odd results at times from Nudis.
Especialy when the negative numbers turn up in the thrust calculations. This throws all data gathered over hours of running out the window! Often this has occured from the simplest of changes of a nicely running engine.

Rossco

Hi Rossco.
I'm so glad to see you back on this forum. How are the Kids?

The Thrust thing is all down to the Internal momentum calculations. This is the thrust, Positive or Negative, generated in each of the 255 cells of the motor. It can overwhelm or play little part in the overall thrust. The point is that thrust is not just that generated at the open ends of the induction and exhaust pipes, you must consider what is happening inside the motor. Try using Excel to draw a graph of the L data on the thrust sheet; it'll give you some idea of how this works.
Of necessity we are calculating thrust over a very limited number of cycles and more importantly these cycles are early in the start-up period of the motor. During this early period the internal momentum has not reached stability and can give apparently false readings.
Some motors I've tested show remarkable results in this respect. The original Type06 and Type07 motors are good examples; they consistently give best results with the induction pipe pointing in the direction of motion. I can only assume that the designers either had a comprehension of these motors beyond anyone I've met or they hit on a formula and ran with it. On a related point, you do realise that you can adjust the location of an optimised u-bend, the location of this bend can also have a radical effect on thrust?

Best Regards
Graham.

Irvine.J · Post by **Irvine.J** » Thu Mar 15, 2007 4:14 am

Gentlemen...
We have successfully completed a full round of tests.
I acertained that the 26mm D inlet pipe was not achieving maximum combustion chamber pressure, leaving more then enough flow to reduce the inlet diameter.

I slid in another flared inlet insert to reduce the cross sectional area by 15%. Which improved running stability and starting with the straight tube fuel line.

We then conducted a series of tailpipe extention lengths to prove my theoretical tuned length was accurate.

Fueling with a straight pipe injector was not an optimal configuration, a new injector was introduced ("The Double D") to improve mixing without artificially entraining more air.

Several runs were conducted at this configuration, with following results...
1- Improved Starting
2- Improved throttle range
3- Very good running stability
4- Tailpipe extention was not beneficial to running performance.

Knowing my thrust setup is not ideal, we tested direct lift of the weight, compared to lifting the weight with thrust stand. We found a great deal more force was required to hold the same weight steady with the thrust stand. Therefor our following readings are CONSERVATIVE rather then unduly optimistic.

THRUST READING AS FOLLOWS
4.5lbs thrust.

www.pulse-jets.com