digital_trucker

Just a little something I'm working on. Another regurgitation from my CAD playings-around.

Tim Wiltse-RCU

DT,

Try to track down post by this forum member "tanzanos". He built and ran a 5 cylinder Norvel a couple three years ago. There was a video too it I remember right.

[link=http://image.rcuniverse.com/forum/upfiles/36452/Id97235.jpg]5 cylinder Norvel[/link]

Later,
Tim

digital_trucker

Thanks Tim! Looks there will be some significant differences between what those photos show and what I have in mind, though.

digital_trucker

Well, here's a quick update on my progress...coming along.

treedog

DT, here's an idea to munch on with christmas coming soon. How about a 2 piece piston head and skirt with a real con rod pin to replace the ball socket type. It would be a round pin with a flat spot on the top side and a screw and plate setup at the top of the piston. the pin would slide in from the bottom? ty for looking . maybe a germ of an idea?
Td
By the way u make the coolest looking drawings hope they work ok for all our sakes.

Tim Wiltse-RCU

treedog,


For what it's worth Norvel(which it looks like DT is using) uses "normal" pinned rods.

LAter,
Tim

treedog

Ty tim saw that about norvel but seeing as they are extinct i thought i might steer him more toward a almost extinct engine like the surefire cox that needs a little engine redesign
Td

digital_trucker

They're based on AP's actually. Turns out that AP uses an even better system than Norvel. Norvel wrist pins are crimped into the piston (not removable). AP uses an actual circlip - removable! That radial has the individual cylinders geared together a la G-Mark. Only difference is that it's designed to have a 1:1 gear ratio (no reduction). That way the shaft valve can be on the main output shaft to save absurdly convoluted intake ducting. With a little luck it might even clear 10,000 rpm. The other issue is that the bottom cylinders will ALWAYS want to run richer. Seems like the common solution is to ignore it or add an extra needle somewheres to lean out the bottom two a little more. I'm thinking of going in a different direction by simply using smaller diameter ducts from the crank to the bottom two...done right it SEEMS like it would accomplish basically the same thing.

As an aside, I'm beginning to flirt with the idea of a 4-stroker built around a .061 piston/cylinder...could be interesting! Probably would have to include modifying the stock glow button or turning down a Galbreath plug though. Room is kinda tight with these little suckers.

The main reason I'm tending to stick with AP piston/cylinder sets is their availability and the difficulty of making them to the right tolerances. Crankcases and whatnot aren't NEARLY as sensitive to tolerances from what I've been hearing.

Geez....now if I only had the equipment and experience to make metal shavings....soon maybe! As it is now all I can do is fart around in the virtual world with CAD.



Another idea wafting about in my fevered imaginings is a twin Kamdax flying wing with the units buried in the wing root.

rainedave

My Feedback: (1)

Now a 4-stroke Wasp would be cool! I can hear the tiny valves clacking now. It would be the absolute perfect Laumer power plant, especially if it had open rockers. Is it possible to make a diesel 4-stroke with fixed compression (no head screw) to save room for the valves? Picture a little .061 open rocker 4-stroke clacking away in the nose of this:

digital_trucker

[link=http://www.minimodelengines.com/index2.htm]DROOL[/link]

SGC

Enya produce a .40ci 4st fixed compression diesel, initial setting up for your prop fuel etc is done with head gsts , details in the everything diesel threads. theres been a couple guys convert os4st's to diesel too.
Stewart

build light

Aww Dave, Ya shoudn'ta gone and done it!

That is just precious! I never have seen one of those!

My Pee Wee .020 alas does not run anymore. I have no idea how it came missing but the crank and piston are gone! This has been a long time ago. So sad.

Robert

digital_trucker

That's cute! Looks kinda like someone started out building a wedgie and - ahem - 'overmedicated' themselves!

lildiesel

Exhaust port in back with a collector ring?

lildiesel

Yes. But you would probably need a bulb type glow plug to preheat the cumbustion chamber to get a start.

On the other hand, the crank could be set in an eccentric (sort of a cam lobe shaped) bearing holder that would be raised and lowered to adjust compression. I've seen this on a small single cylinder four stroke diesel made by some guy in Germany. This method of compression adjustment was used way back in the forties on some production engines and, slightly more recently, on the Telco CO2 motor. Might be a nightmare to engineer for a radial, though.

lildiesel

FWIW, a flying acquaintaince lost that circlip while replacing a con rod bent while hitting his Wasp with an electric starter when seriously flooded. Odd how that part is not among the replacement parts listed. I plugged the end of the wrist pin hole for him with three thin (.015) teflon discs cut from sheet stock figuring that would make an OK retainer. That was about six months ago and he hasn't slugged me at the field yet, so it still must be working. [8D]

BTW, if I ever do this again I'd check into getting a length of teflon rod in a suitable diameter and just cutting one longer plug. Those discs were tiny (something like 5/64 or 3/32)!!!

digital_trucker

lildiesel: Actually, the exhaust would exit the front of the cylinders and go into the main crankcase housing to lube the gearing. I haven't gotten that far yet on the drawing.

So it's a circlip ye be needin'? How about this? Global Part# 212379 AP part# 06213 (apparently)

http://www.globalhobby.com/public/gallery/212380.asp

http://www.globalhobby.com/public/mfr/ap01.asp

treedog

Think we can strap this 1 on a 1/2 a all u engine lovers?
Td

lildiesel

Okay, but you might get concerned with the distribution of the "exhaust lube": what kind of backpressure you'd get, and how to vent the crankcaee for pressure and loss of excess lube.

digital_trucker

Shouldn't really be much of a problem, crankcase induction is separated from the gearing section. This is all experimental anyway...I'm leaning more towards a linerless bolt-on cylinder (sorta like what you'd get if Cox and Norvel had an illicit affair )

digital_trucker

Okay folks, I've backed off on the radial for a bit. I just wasn't happy with the results using AP components. I went back to square one with a single. I did use some concepts from the AP, especially in the conrod/piston area. The design needs a bit of tweaking yet, probably adding another fin to the cylinder and maybe stretching the crankcase just a tad more.

Here's the specs:

Displacement: .049 c.i.
Bore: .40"
Stroke: .39"
Linerless construction similar to Cox
AAC piston/cylinder
Double ball bearing on the crankshaft

mylamo

My Feedback: (1)

Front rotary,Disc or reed ?

digital_trucker

Front rotary (I need to work on the carb yet)

mylamo

My Feedback: (1)

Yeah DT we need to get some explosives into
this puppy.
Ralph

digital_trucker

Well, here's the stage I'm at so far. I'm considering just using an AP .061 carb for it. Hopefully I can work on it some this week, maybe by next weekend I'll have the drawing completed. Something else I'm considering is having a header instead of a muffler and using one of FlyQuiet's mufflers or pipes on it.