Slipstream PJ ! Now with vid.

Chadly33 · Post by **Chadly33** » Fri Feb 29, 2008 6:43 am

Built this one to put on my RC boat ! Have yet to mount full body augmentor. Hopefully be finished by next weekend. :twisted:

Chadly33 · Post by **Chadly33** » Fri Feb 29, 2008 6:44 am

Rear view !

Post by **Mike Everman** » Fri Feb 29, 2008 7:24 am

I do love the twin tails!

larry cottrill · Post by **larry cottrill** » Fri Feb 29, 2008 12:45 pm

Yes, Chadly -- another really nice one built around an oval. Very sensible design, nice low profile "side view".

Do you have any worries about the expansion of the tailpipes between the fore and aft welds? I'm guessing you decided that the "looped" geometry of the pipes will take up any expansion forces generated, and that's probably a safe bet. This will be fun to see in action!

L Cottrill

metiz · Post by **metiz** » Sat Mar 01, 2008 12:04 am

that's a pretty slick looking lockwood dude. Nice job.

I've been toiling with the idea of making a basic lockwood with, say 4 exchaust pipes wich would then be thin enough to be rolled around the cc and eventually come out in front but NOT sticking out. This way you could have a hugely tiny 50lb lockwood with only a realy realy fat cc wich is only as long as the cc plus the intake.

what say you?

Chadly33 · Post by **Chadly33** » Sat Mar 01, 2008 2:04 am

Sounds like your thinking like me!lol Have already drafted up the plans, I use slightly different dimensions in my engines just through experimenting on my own wich is probably why all my PJ's start airless. I am just collecting the materials for it now, will have six exhaust tubes though and a full body augmentor. CC is based on the 70 pound engine plans.

Post by **Mike Everman** » Sat Mar 01, 2008 2:42 pm

Ooooh, very good. I've always wanted to try that. The wall I mentally run into is all that surface area drag, and the extra turbulence of rolling the exhaust stream around a long small radius. It's already turbulent enough.

At least it's less drag this way vs. an annular design. Short and fat will be fun to see!

GRIM · Post by **GRIM** » Sat Mar 01, 2008 4:04 pm

Hey Chadley
Very neat , what diameter are the tailpipes on the rc boat engine ? i cant get a scale from the background , and being as your previous combustion chambers have ranged from ?? to 18 litres, well this could be a big SOB RC BOAT

The octopus locky idea is great too , cant wait to see something along them lines

Great stuff

Chadly33 · Post by **Chadly33** » Sat Mar 01, 2008 11:38 pm

No bends in the six piper except enough to allow the pipes to attach directly to the sides of the combustion chamber, think of a 90 degree layed over the edge of a bench then cut level with the bench top gasses are directed to the outside of the exhaust end of the combustion chamber with an inverted and slightly rolled cone. Also playing with the idea of inverting the intake end on a standard lockwood design then mounting twin intakes(with bends) to the sides (top and bottom) facing in so as to set up a cyclonic flow in the CC.

Chadly33 · Post by **Chadly33** » Sat Mar 01, 2008 11:42 pm

GRIM wrote:Hey Chadley
Very neat , what diameter are the tailpipes on the rc boat engine ? i cant get a scale from the background , and being as your previous combustion chambers have ranged from ?? to 18 litres, well this could be a big SOB RC BOAT :shock:

The octopus locky idea is great too , cant wait to see something along them lines

Great stuff

The exhausts are 3/4 of an inch, the CC is about the size of a large hip flask (CC fitted in my back pocket) Dont usually play with engines this small they are just too finniky!

Chadly33 · Post by **Chadly33** » Tue Mar 04, 2008 3:37 am

Well got the little engine home and mounted to the stand, started straight up and burbled away. I used a converter from standard gas cylinder to the smaller type tap but think it still has too much pressure or not enough of fine tuning as it is very touchy. Seems to go in and out of resonance and is heating up in the exhausts rather than the CC. will take a video and post it as soon as I get back from NZ. Have too go over to sign off some work on a helicopter!

Chadly33 · Post by **Chadly33** » Fri Mar 07, 2008 6:00 am

Short vid of the little baby PJ running. Had to put a divider in to stop the exhausts sucking in the intake gasses but the augmentor will fix this problem!http://www.youtube.com/watch?v=1EeJTnPSiT8

Chadly33 · Post by **Chadly33** » Wed Mar 12, 2008 1:06 am

playing around with the CC before cutting for the exhausts and intake I squirted a little aero start into the CC and lit it even with a tiny hole in each end cone the little thing would start and have a short run ! one hole was slightly larger but not by a noticable amount and it would mainly exhaust fron this end. to run with no pipes or flares seemed strange to me, could it have something to do with th elipticle cone ends changing the breathing pattern of the CC ? any thoughts or comments on this would be much appreciated as I cant help but think something can be done with this phenomenon.

Cheers Chad.

Post by **Mike Everman** » Wed Mar 12, 2008 3:35 am

Yeah, man, throw some fuel in at any time in the build. I've learned so much from that. I've tried pots with holes at both ends, but don't remember if there was much revving going on. the elliptical sure makes you think. Mind's eye on non circular toroidal vortices. How many of your friends can say that? ha

PyroJoe · Post by **PyroJoe** » Thu Mar 13, 2008 9:56 pm

"any thoughts or comments on this would be much appreciated as I cant help but think something can be done with this phenomenon."

From the description it sounds like you have a favored exhaust side, this leads to a pumping action. I haven't seen an opposing opening jar run, it seems like it will always get a to and fro cycle and dampen out. Maybe Mark has seen one.

Good work BTW