Logan

multispool · Post by **multispool** » Thu Jul 26, 2007 8:18 am

Done a search but can't locate any working drawings of a Logan
Can anyone help please?

multispool · Post by **multispool** » Thu Jul 26, 2007 11:11 am

Hi Mark,
A second search revealed your small side port engine, Was this sustainable without forced air? if so would you be prepared to reveal dims?

Mark · Post by **Mark** » Thu Jul 26, 2007 2:17 pm

While it is a very crude Logan, it does sustain easily without forced air. In fact, it has to be one of the fastest little pulsejets for starting if you use methanol and prime it first. No fuss, more often than not it's just an instant on effect when you light the tail end using a cigarette lighter.
The side port probably makes more thrust than the tail end so an elbow would be needed to deflect the thrust rearward if you wanted to push something.

Here's the deeply scientific specs. ha
The exhaust pipe or tail is 12 inches long and 1/4 inch diameter plumbing pipe. Recall plumbing pipe is like lumber, a 2 by 4 isn't really a 2 X 4. It is most apparent with the 1/8 inch plumbing pipe nipples.
The bell to the combustion chamber is a 1/4" to 3/4" size.
The combustion chamber is 3/4" wide and 4" long.
The side port is 1/8" diameter by 1.25 inches long. You will need to drill and tap a 1/8 inch plumbing pipe size hole in the side of the combustion chamber. You could also use a 10 mm tap instead of a 1/8" National Pipe Thread tap for 1/8" plumbing pipe. You only want the side port nipple to screw/bite into the side port a few turns so that is is flush with the inside walls of the combustion chamber. When you cut the tiny 1/8" diameter nipple to 1.25 inches long, deburr the inside edges so that air flow will be smooth.
You can cap the head of the combusiton chamber with a 3/4 inch cap.
For fueling, you can do it several ways. I've run mine on methanol, acetylene and MAPP gas successfully.

multispool · Post by **multispool** » Thu Jul 26, 2007 2:24 pm

Thanks very much for the dims. I can probably make it easier out of STA so when I get back home next week will make it up and see what it runs like!

I have no interest in thrust so will keep the side port straight!

Are your pipe diameter measurements internal?

Mark · Post by **Mark** » Fri Jul 27, 2007 1:38 am

The 1/8 inch plumbing pipe side port actually measures about 1/4 inch internal diameter oddly enough. I don't know what the rational is, but it's called 1/8 inch and more like 1/4 inch. The 3/4 inch pipe is closer to 7/8 inch diameter if you were to deburr the inside lip. And the tailpipe/exhaust 1/4 inch is really around 1/3 of an inch internally.
I will be eager to hear of your adventures. Happy fabricating and best of luck. It is an infinitely easy starter with methanol.
Mark

CG · Post by CG » Fri Jul 27, 2007 5:23 am

multispool wrote:I have no interest in thrust so will keep the side port straight!

As a pressure-gain combustor for gas turbine experiments then?

multispool · Post by **multispool** » Fri Jul 27, 2007 10:02 am

Ah, the throat is at 25% so its a crooked linear (my colourful description).

CG: No intentional direction on this. More a case of playing, and seeing where it leads. Hope to end up with a nice cross section of medium to small VPJ types.

Of course, a Pressure gain Burner would be very nice and a (quiet'ish) VPJ would perhaps be the starting point for such a design. I am aware of one such device (VPG >turbine>power turbine) currently in existence and powering a vehicle. I was going to video it running but the flooding in the UK put an end to my travelling. However a colleague living closer did manage to get there and take pictures and video, and yes it is in existence and driving a vehicle. As to its efficiency, or benefits, this contraption is in its infancy. The Designer/builder an elderly modest man suffering a terrible illness makes this all that much more incredible achievment.