Back with the BIG LADY

[wakmat]

Hello

it's been a while since I posted(new job). Anyway while shifting gear I found my cone templates for Lady Nancy Astor so I thought I would give her a try.I have half built this engine before,but my boss didn't know what it was so he tossed it out.So here she is with 4 intakes.Enjoy

[Mike Everman]

Hey Wak, nice build!

[larry cottrill]

GO, Man! Let's see that sucker howl.

Yes, nice work so far. Looks like you just need the front dome and some good mounting points.

Keep us posted -- I hope you have better luck than the earlier attempts. You can probably expect to spend some experimental time getting the fueling configured just right.

L Cottrill

[larry cottrill]

Looks like you just need the front dome and some good mounting points.

Oops. OK, I see now -- the upper photo is the later of the two, and I guess you've got her buttoned up and tied down. Looks like you're all set to go.

Good luck!

L Cottrill

[metiz]

haha that one is awesome! Is that a lady anne?

[larry cottrill]

haha that one is awesome! Is that a lady anne?

This is the "latest" or "final" version of the Lady Nancy Astor. Berry (in Holland) never got his to sustain. However, he didn't have much time to mess with it, and from what he was finding, we were more-or-less convinced that the fueling geometry needed some tweaking. I think fueling one this size could be a lot different from the ideal layout of a small one, with the spouting point much farther in. This lady is about a metre in length.

L Cottrill

[wakmat]

Hello

Had a go at firing her up yesterday,couldn't get her to lock in,but got some really good barks like it was trying,so a bit of tweaking is needed.I think my injecters are to far out,will change my gas manifold so I can adjust the distance while she is running.This thing has some serious power,the few times it was barking and half locking in it was lifting my test stand,and it would have to be 40kg.Also I think this engine needs alot of air pressure to lock,I was only using 100psi and a air duster so that might be something else to try.Will keep trying and keep you all posted.
Tim

[wakmat]

hello

had another go at firing her but no luck,I tried moving the injectors in while feeding air in,it appears that the further out the better it seem to run,I'm using the flared and pinched type injecter,the same as on my lady jane.Also tried a tube in the exhaust it seemed to make it harder to get to bark.next on my list of things to try is a different injecter,I was thinking a 6mm copper ring on a straight tube with 4 1mm holes on the ring facing down the intake,I tried it with 30psi of air pressure and it had excellent suction on the intake.Also I went back to the plans and my intakes are about 10mm to long,may cut the flare off and make a sliding intakes.

Tim

[milisavljevic]

Hello Tim,

After finding this thread I ran an analysis of this FWE using the Rev.04 specification posted
by Larry, as I do not have your changes (eg., intake diameter) or your "as-built" dimensions.

That being said...

This FWE will not self-sustain and suffers from multiple design failures. It is not possible to
overcome these faults by adjusting either the intakes or fuel delivery system. While having
access to the "as-built" dimensions of your intakes (ie., length and diameter) would be nice,
I can tell you that going from three intakes to four (presumably lower diameter) intakes did
not materially alter the operating characteristics of this duct. You would have better luck in
replacing everything aft of the combustor, as many of the design faults originate in the tail.

In a nutshell: the combustor port area (or confinement ratio) is excessive for this size class
and the entire tailpipe is (quite) over-expanded, causing severe separation in the boundary
layer as successive pulses travel downstream. Even if the duct could self-sustain or was run
under forced-air, thrust production would oscillate wildly (you experienced this as "jerking")
and throttle range would (likely) be quite limited (ie., flame outs with little/no provocation).

Our friend James Irvine has a video that illustrates tailpipe separation effects rather nicely.

Limit thrust is disappointing for a duct this size (over 16 liters), at perhaps 11 kilograms or
24 lbs. Not that you can get this, as the predicted operation is unstable (as I stated before);
however, transient forces experienced on starting attempts ("jerking") may reach 38-49 kg.

I modeled the nominal resonance state for this duct (Rev.04) as ca. 161-164 Hz at an open-
pipe acoustic temperature of 288 K (15 C). This is ca. 100 degrees cooler than the FWE-VIII
(aka, "Lady Anne" Rev.08) and is indicative of a duct that is a determined non-starter. If it
is of serious interest to you for this duct to run in close to its present configuration, it may
be necessary for you to rig your starting air to drive both intakes simultaneously, and settle
for forced-air mode, only. Even this proposition seems doubtful, due to the over-expansion.

Of course, there is always the option of "major surgery"...

Cheers,
M.

[Berry]

i hope you are able to get it runnig !!!

Mine is till in the shed somewhere was not able to make something else of it because it looks cool but could not get it running.

good luck and happy new year everyone.

Berry

[wakmat]

Hello

thanks for the help Milisavljevic,the more I look at this engine compared to my Lady Jane Grey the more I'm starting to think the exhaust portion of this engine is to big,My intakes are 38mm id lengths are 175mm flare to mitre,this is 10mm longer than the plans,all other demensions are as the plans,Would it be possible to chop the rear half of the choke and exhaust tube of and lengthen and reduce its diameter,and if so by how much.? I think this engine has alot of potential,and I would really love to get it self sustaining.Any thoughtsn the tail reduction would be great,if modifying the tail is possible I would chop it and use a vclamp to change the pipe.

Thanks
Tim

[milisavljevic]

Hello Tim --

Thanks for the dimensions of your intakes and that the rest of your build was to Larry's Rev.04 spec.

Would it be possible to chop the rear half of the choke and exhaust tube off
and lengthen and reduce its diameter...and if so by how much? Any thoughts?

No worries, mate! Let me update the model with your intake setup and then I can suss out the least
invasive surgery required to bring this beast to a full-throated roar. Warning: it could get bloody!

I will be working on this tonight and tomorrow, so please keep your pants on! I'll post when I'm ready.

Vancouver_NewYearsEve.png

Cheers!
M.

[wakmat]

Hello

Thanks for the hand,I'm in the process of trying sum different exhaust tube and choke tube,just jaming them in from the exhaust,my new fuel ring seems to work alot better,I can get a howl with half the amount of air I was using with my old rig.Can't wait for your input on the tail.

Thanks
Tim

[larry cottrill]

M and wak -

Thinking back on the difficulties that Berry (an experienced builder of big engines) had with his build, I'm not totally surprised that significant adjustments are needed. My only comment for wak would be that the choke area is quite modest -- I'd bet that it can be left as-is and all the adjustment taken by shortening and/or narrowing the tail cone. But, let's see what M has to say. I agree fully with the plan to make the intakes adjustable -- it's what I recommended in the first place. Of course, tuning four intakes will be a grand hassle, but you knew that.

To Berry and "vermin" Vern (who also tried one of these): My apologies for a design that was apparently pretty far off the mark. I wonder if the basic problem was trying to use the temperature layouts that worked for the smaller engines. Once M and wak get this design "back on track", I hope you'll go back someday (if you want) and re-work your original builds to get a couple of nice motors.

I wonder if I wasn't experiencing a similar though perhaps less extreme problem with my Lady Guinevere build. I have thought about going back to that one and gradually "notching off" the tail cone to see if she can be brought into resonance.

L Cottrill

[milisavljevic]

Hello Tim --

I updated the model to reflect your quad-intake setup. I did forget to ask about your inlet flare diameter.
I have assumed 51 mm for now, but would prefer to use the correct diameter in my calculations. Thanks.

I can get a howl with half the amount of air I was using with my old rig.

Any chance of recording this sound and posting it here? No overstating the value of audio to my analysis!

Can't wait for your input on the tail.

About there, mate. You will have to lose the entire tailpipe, ie., everything aft of the combustor section.
We may be able to salvage part of the exit cone by cutting it down a bit (lengthwise). The "camel hump",
that acoustic abomination wedged between combustor and exit cone, has to got to go. Hoses everything.

I will provide you with dimensions for the replacement tailpipe segments; there will be at least three (3).

The bad news is this: in keeping the combustor more or less intact (so at least something survives from
Larry's original design), thrust will be limited to about 11 kilograms (24 lbs). Maybe a little more, or less.

The effective length of this combustor, ie., what contributes to thrust production, is under 200 mm, and
this is only a little more than the effective combustor diameter, which limits thrust production, BIG time.

I am looking at the idea of welding a cylindrical shell inside the combustor, to block off wasted volume.
Such a shell leads from the head of the combustor to just before the intake ports, matching the diameter
of the combustor cone at the termination, and solves the thrust deficit problem. No worries, just looking!

Don't want to make this too complicated...

Cheers!
M.