deHavilland Cirrus 1/6 pics

[Swede]

Thought you guys would like some pics... I produced this engine a few years ago from the Merritt Zimmerman design as published in SIC. The crankcase castings came from a fellow in Ohio, USA. I don't believe they are available anymore.

Some history - I ran this engine heavily on the bench, but have never flown it. After running it over a period of weeks, and happy to have it tuned up and running well, I tossed some anticorrosive oil into the cylinders and crankcase, and put it up on a shelf. Bad idea - the castor oil gummed badly over the last couple of years, While the pistons and crank were free, the tappets were locked, and the engine overall had a nasty, gummed, dusty coating, and in spots a touch of corrosion. Yuk. I decided to tear it down and clean it up.

The bore is .562" / 14.3mm, stroke roughly the same, 4-cylinders inline, glow ignition, poppet valve. The crankshaft is one piece, 2-piece connecting rods, and the split rods make use of shim bronze bearing surfaces formed in a custom die. The pistons are cast aluminum, with 2 rings per piston. Of course, I managed to break a ring trying to free said ring from its nest of gummed castor in the piston after tearing it down, and, unable to locate a spare, had to turn, split, and heat treat a new set of rings from C.I.

First pic: The engine viewed on the glow-plug / exhaust side. The exhaust stack is partially removed. The head is actually one piece of aluminum, machined in a fashion so as to appear to be 4 separate heads at first glance.

Second pic: The intake manifold is removed, revealing the intake ports, which branch via a "Y" inside the head to feed two cylinders for each port hole. The pushrods and rockers have been removed. The tapets are obvious at the bottom of the pic. Note the castor goo and overall sad state of the engine.

[Swede]

Third pic: The bottom of the crankcase is pulled, revealing the crankshaft and rods. The crankshaft was lathe turned using a bar of normalized, hot roll, medium-carbon steel. Not heat treated and somewhat soft, but this engine is designed for casual use, not hundreds of high-speed hours!

Final pic: One of the trickier parts, the tiny camshaft. As published in SIC, the prints produced a cam which would have run the engine in reverse! This first cam drove me nuts while I was trying to time the engine. Ultimately I was convinced that the magazine was in error, and sure enough, they were. I wrote a letter to Bob Washburn, the publisher, who forwarded it to P.E.L. (Eric) Whittle, the builder, a remarkable IC enthusiast living in the U.K., who verified the error. Of course I needed to produce another cam. So now I have a pair of camshafts, one for forward, and the other for reverse operation!

The engine is completely cleaned, lubed, and back together. It looks nice once again. I hope you guys enjoyed the pictures.

[Ken_Shea]

Thanks Swede, sure did enjoy them, there is something about little engines that seem to captivate the viewer.

Thanks
Ken

[Swede]

Thanks Ken, one last picture with the Cirrus restored and cleaned up a bit. Engines with open valveworks never look right unless the rockers are back on!

[nervis1]

Hey Swede, that might as well be magic to me, that is really amazing.

I saw a big display of scale engines at the Phoenix Intl airport earlier this year. Lot of stuff like your pics and some big radials, even an 18 cyl radial, turbines, v12 car engines etc. I don't think I could ever make something like that...just don't have it in me.

Great work.

Do you have a website where I can see more pics of your projects?

[Ken_Shea]

Dave, I always check out and see if the poster has a web site by left clicking on their name, it will bring up a list among which is a link to their web site if they list one, in your case I would left click "Nervis1", but you ain't got one .

Swede is a true machinist, left click his name, and be prepared for a treat.

[jrc347]

I still read your webpage from front to back every couple of months. I am amazed at the skill you have.

[nervis1]

Hey the 5 bears guy.

I've seen that site, never knew it was Swede.
Were not worthy Swede. That is some fine work....damn a turbine, 9 cyl radial...amazing.

Swede I was rootin for you on that collet, sorry it diddn't work out.

[Ken_Shea]

Were not worthy Swede

Yeah, me too, we have all this fancy equipment but it makes me feel kinda like being all dressed up and no where to go

[Ken_Shea]

Dave, here is another guy that is really good, do a search for post by Stevie, haven't seen him for a while interesting, experienced and talented like Swede.

I am kissing up in case I need help down the road from Swede.

[ger21]

Originally Posted by Ken_Shea Dave, here is another guy that is really good, do a search for post by Stevie, haven't seen him for a while interesting, experienced and talented like Swede. I am kissing up in case I need help down the road from Swede.

I saw a post from Stevie today.

[Swede]

Thanks everyone. Glad you like the engines. I came to this site to kiss up to everyone else, as I am trying to learn CNC. I've gleaned information from gurus here that is simply unavailable anywhere else; that is, practical rather than theoretical knowledge. My thanks to all of you who have helped me over the last year or so.

I have the CNC hardware now, but I'm still horribly stuck on CAD, specifically Rhino. There's nothing wrong with the software... it is me, for some reason I just don't "get it" yet. I'll keep plugging. All of the small parts on these engines simply beg for CNC since they are so repetitive. I think that's my problem, I need to start a major project which will use my little CNC mill. That'll motivate me to stop fiddling and actually start designing and cutting parts.

This is me and my copy of Rhino3D!

Swede