Big Lady for FWE Test Measurements

[larry cottrill]

Thanks, Joe! Got the mounting lug welded in by Matt this noon. Man, that baby is solid! And I did get some final photos, a couple with Jim and Matt. The only regret is that I never got a single one of myself with this engine, and in some ways it's the nicest one I've been a part of (admittedly, mostly done by hired professionals). Now I'm stuck here at work doing my real job, waiting to work on an emergency fix for the live branch systems, and I have no idea whether I'll get out of here in time to get to the UPS Store or not. Sheesh.

Anyway, the end result is very nice, I think, and if she's in tune there should be a few exciting days ahead. I hope our friend gets some good shots & video of the actual testing setup & initial runs. I'm hoping for a heck of a data analysis writeup, as well.

L Cottrill

[Dang911]

Its looking real good! Thanks for your efforts and speedy build to make this possible... Oh and for swage caps add another $300 and nuts and farrels another $300, lol, not to mention instrumentation. This should be the most expensive hobbyist pulse jet ever.

Real pulse-jet experimental data ~ Priceless

[larry cottrill]

Well, Greg, now everybody knows who I'm in cahoots with on this one. I'll take the liberty of posting the photo you sent along, since it's published on your Facebook page anyway.

For everyone else, here's sort of where we stand:

I won't be shipping today; probably noon tomorrow. The only good part of this is that IF I have another roll of film left at home, I might be able to get a pic of myself with this thing! All the photos today were on real film, so it will be next week before I'll have scans to post.

Greg's remaining time at this facility is limited; only a couple more weeks. And, it's impossible to tell how much time he'll have to work with this, since it has to be shoehorned in between "real" test jobs that need to be run. But for the moment, it looks like there's some available time coming up. The hard part is really that there will be little patience for tinkering and tuning, since other technicians and a lot of costly equipment will be involved. So, it has to come up and run pretty darned soon after setup.

Greg, I really think the thing to do is make a fairly long sliding tail sleeve, slightly sloppy fit over the tailpipe, but with a simple screw clamp to seize the pipe. Cut your tailpipe a little (maybe 3 or 4 inches) short of what I gave you. That way, if it doesn't sustain, you can add an inch at a time with zero effort and just a moment of delay. Your only additional tool will be a good leather work glove. That should give you a motor that will be running smoothly in minutes! And, you can go ahead and make the sleeve so you'll be all set with it when your engine front end arrives. Just for grins, you can always start out with the sleeve set for my specified length and see if I just happened to hit it right on the head.

Also, keep in mind that it IS possible for internal acoustic reflections in an indoor space to keep these things from running well -- or maybe, at all. If at all possible, aim the rear of this thing out a big doorway to the open air. Again, if possible, try to cap all the fittings and get an outdoor run first -- that wouldn't involve other personnel nor any of the fancy test gear, and it could save you a lot of grief on the live test bench. Of course, I realize they may have heavy restrictions on what you can do and/or where you can do it.

But, my friends, one way or another, we ARE going for it! Stay tuned ...

L Cottrill

[PyroJoe]

Larry wrote:
"The hard part is really that there will be little patience for tinkering and tuning, since other technicians and a lot of costly equipment will be involved. So, it has to come up and run pretty darned soon after setup."

It appears there will be little time for scavenging, so I offer a PLAN D tail length. (Larry usually has PLAN B and PLAN C covered)

A length of "last resort" so to speak. It would be handy to have a extension that can increase the total tail length to 49"(1245mm)

Not sure if it will fit within the test rig, but may be worth a shot if nothing else is working.


Joe

[larry cottrill]

A length of "last resort" so to speak. It would be handy to have a extension that can increase the total tail length to 49"(1245mm)
Not sure if it will fit within the test rig, but may be worth a shot if nothing else is working.

This amusingly reminds me of what I have at home, where I use 1.25 OD antenna mast for almost every straight tailpipe I build: I cut some short "split collars" from the tube and tack welded a collar on one end of several lengths of the tubing: one 16-inch piece, one 8-inch piece, one 4-inch piece, one 2-inch piece, and a 1-inch length with a slightly flared end. A little binary math will show you that with these sections that "socket" onto each other, I can build up to 31 inches of extension in 1-inch increments if I keep my wits about me (which is more of a big IF all the time ;-). The slight leakage at the joints seems to be meaningless.

One thing I neglected to mention is that the total weight of the assembly after welding on the mounting lug is about 5.5 lb, or somewhat under 3 kg. Of course, this is not the total engine weight, since the 3-inch OD tailpipe tube will be a significant fraction of the final value.

L Cottrill

[Dang911]

I will first try the engine as in, but if not I think I could scrounge some aluminum sheet to make a sliding tuner. I believe I just recycled some DANGER FLAMMABLE GAS, and DANGER TEST IN PROGRESS DO NOT ENTER, signs that I could hammer into form. Lets just hope all goes well and it runs right out of the box. And as far as room goes, the test cell is quite large, with 16" thick concrete vault style walls which have a solid steel plate in them somewhere. The cell doors look like your typical bank vault doors, big thick steel on huge hinges. The cell also has a new emergency blow off roof in the event the lab blows up "again" yes a little over a year ago we experienced an explosion when a 400PSI natural gas hose blew mid test and the roof was blown off.

[larry cottrill]

Got an email from Greg that he has received his engine front end in good condition. (He is impressed ;-) He tried fitting the tailpipe piece he has, and it fit nicely, with just a bit of tapping the far end to drive it in. So, with luck, today will be a time of "preparation" for testing. It also looks like a reasonable amount of lab time has opened up in the next few days. I have encouraged him to start up a new thread when he gets to a good "starting point" to talk about the testing itself.

Stay tuned ...

L Cottrill

[Dang911]

A new thread has been created for the final assembly and testing, viewtopic.php?f=3&t=5246

[larry cottrill]

I FINALLY got my film processed, so here are the final photos before the engine was sent to Greg for testing.

MANY THANKS to my friend Jim Russell for his skills, tools and shop, and to his son Matt for doing much of the welding on this engine. Construction would have been utterly impossible without their kind and skillful assistance.

L Cottrill