Lady Anne variation.

James D · Post by **James D** » Tue Feb 06, 2007 9:11 pm

I decided to modify my last Lady Anne build (rev 02) I've now made it similar to Larry's latest revision 06 drawing, except I used two intakes 20mm diameter, which I think gives roughly the same area as one at 28mm (as per rev 02 drawing).

I had good fun testing it today, but the results were a slightly mixed bag. I was fuelling it on propane down both intakes, it started quite easily and seemed to run strongly, but would quit very suddenly as it got warm.

I'll post a video showing one of the better runs. At the start when it moves on the stand its lifting around 2.75lbs of water, you can see me add more, and its holding rock steady at 3.25lbs, But as I'm about to add more, it quits.

Hopefully looking at the heat pattern, lack of flame from the tailpipe and the frequency (which is still rising when it quits) someone can suggest what adjustments might be needed.
I think this intake layout has potential, it just needs a bit of tweaking.

James D

larry cottrill · Post by **larry cottrill** » Wed Feb 07, 2007 2:15 am

James -

Good video! I stick with my earlier observation that if it runs and dies, the main pipe is a little(!) too long for the intake(s). What I would try next is adding a little clay or putty to the intake flares, just like the southern James did a while back, to lengthen the intakes slightly - a couple of mm. Then, try again and see if it runs longer (or maybe sustains ok). If it gets better, add more.

The total area of the twin intakes is indeed about right, but the Q is higher, so they will be more sharply tuned than a big, stubby one. Also, the smaller diameter would mean a slightly smaller end correction at the flare, meaning it should be just a bit more rearward.

Nice work, though. The thrust is coming up closer to what I'm hoping for.

L Cottrill

El-Kablooey · Post by **El-Kablooey** » Wed Feb 07, 2007 3:08 pm

WOW! That is most definately the most beautiful PJ I've ever seen. Great video too, I watched it 3 or 4 times. I can't get over that engine, very nice lines, and great craftsmanship.

Great job Larry, and James!

El-Kablooey · Post by **El-Kablooey** » Thu Feb 08, 2007 12:43 am

I just had to watch it a few more times. I really like the look of that one guys. It actually looks more like a propulsion device and less like an exhaust pipe than most designs. It appears to be really putting out some major thrust for it's size too! Anyway, I am very impressed I love the double intake on that design. I'm gonna have to build one too.

Keep us posted on your progress please!!

Post by **Mike Everman** » Thu Feb 08, 2007 4:38 am

3.25 lbs is wonderful! Gotta love it.

Johansson · Post by **Johansson** » Thu Feb 08, 2007 6:22 pm

A beautiful engine. Great work, James!

//Anders

James D · Post by **James D** » Thu Feb 08, 2007 10:09 pm

Thanks for the comments guys, I had lots of fun testing it. In the video you can see some water get blown out of the jug as I'm pouring, it just seemed to atomise instantly as it became airborne, pulverised by the air pressure, an interesing effect to witness close up.

The other thing I forgot to mention, at the end of the video the frequency is getting close to 370hz, which is higher than expected. If the centre of combustion had moved 'south' towards the tailpipe would that give an increase in frequency or is it just likely to be running hotter?

James D

Irvine.J · Post by **Irvine.J** » Fri Feb 09, 2007 12:42 am

James That is a fantastic build, I thought i'd posted here but I guess I didnWe too had water splashing out everwhere like crazy. When you ready to add a tailcone and start tapping out let us know. I think we might see slightly more controlled running an a slight drop in power however for atleast the next week I"ll be unable to test anything, so I look foward to any improvement/modifications and experiments you do. This engine is very promising indeed! Great build, it looks fantastic. Good work.
James.

larry cottrill · Post by **larry cottrill** » Fri Feb 09, 2007 1:50 pm

James D wrote:The other thing I forgot to mention, at the end of the video the frequency is getting close to 370hz, which is higher than expected. If the centre of combustion had moved 'south' towards the tailpipe would that give an increase in frequency or is it just likely to be running hotter?

I'm 99 percent sure it's just the temperature rise that's doing it. Test this with a re-run of your earlier experiment of shielding the tail end from the cooling air pulled along by the intakes, using pieces of sheet metal. If I'm right, that will make it quit much sooner (after a cold start).

If extending the flares doesn't seem to be going in the right direction, go back to trying your nice tailpipe sleeve with the three screws, BUT proceed VERY gradually in lengthening. You're very close - probably just A FEW MM AWAY from the exact length needed. So, you need to start from where you are and work the length outward in very small increments - the intake will be about three times as sensitive as the tail end to changes in length, of course.

L Cottrill

James D · Post by **James D** » Sun Feb 25, 2007 5:15 pm

I made some changes to the twin intake Lady Anne this week, I moved the intakes forward slightly, angled them so they point more towards the front dome and made them slightly longer. I also modified the fuel pipes to give a much better spread of fuel, they're now similar to Larry's lemniscate design but with four holes instead of two.

It seems to run really great now, the frequency has dropped to around 355hz and it now puts out 4lbs+ of thrust along with the most insane noise I've ever heard. I would say it must be louder than two normal FWEs running together, it really is quite disturbing;>)

larry cottrill · Post by **larry cottrill** » Mon Feb 26, 2007 1:34 pm

James D wrote:I made some changes to the twin intake Lady Anne this week, I moved the intakes forward slightly, angled them so they point more towards the front dome and made them slightly longer. I also modified the fuel pipes to give a much better spread of fuel, they're now similar to Larry's lemniscate design but with four holes instead of two.

It seems to run really great now, the frequency has dropped to around 355hz and it now puts out 4lbs+ of thrust along with the most insane noise I've ever heard. I would say it must be louder than two normal FWEs running together, it really is quite disturbing;>)

EXCELLENT! Congratulations, sir!

Doggone it, James - where's the video of this beast ???

If you're getting anything over 4 pounds burning propane, we've beat the Dynajet already (for a design with the same overall length)! What's the total weight as it sits right now? Are you willing & able to post a simple drawing of the final "as built" dimensions?

If you're willing to try a heat-recovery ramjet shell, let me know and I'll work out the cone dimensions for you. Your biggest problem would be that you would have to keep it "split" until you get it around the engine body, because you won't be able to slide it on over one end or the other.

Man, once again - nice work!

L Cottrill

James D · Post by **James D** » Mon Feb 26, 2007 9:09 pm

Larry, It definitely makes well over 4lbs, I was using a spring scale to measure thrust and it showed 2kgs, which is about 4.4lbs, however I'd like to do some more tests using my original water lifting rig, to confirm this figure.

As for weight, made from 0.7mm stainless it's 550 grams (1.25lbs) so if built from 0.5mm it should be well under 1lb.

Here's a video clip.

larry cottrill · Post by **larry cottrill** » Mon Feb 26, 2007 9:22 pm

Man, I really like it! Especially enjoyable (for me, not you ;-) was the struggle to keep the carriage down on the table!

Wonderful stuff, James!

L Cottrill

Irvine.J · Post by **Irvine.J** » Mon Feb 26, 2007 10:36 pm

James thats excellent, well done! 4lbs! Thats fantastic. Look foward to more documentation on it. Good video too :)

Mark · Post by **Mark** » Tue Feb 27, 2007 1:24 pm

I was wondering how much water this jet holds? If you filled it with water we could get an idea of the volume. For example, I've filled my Dynajet with water and it holds about 2.5 cups of water or a just a little under 600 ml.
Mark

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