Lite-Weight Exp Cub

I am just starting a exp supercub project using a Spraker Fuselage and Colt wings and tail. My goal is to end up in the Lite-Sport category. I will be using a 0235 C1B and will adjust certain parameters as required (Single Place, one wing tank, baggage allowance) I would like to make the cowl like a J-3. Is this possible with a 0235 using a starter and ring gear? I am currently using a
skytec starter and nippon densco alternator on this engine. I may get rid of alternator to save weight and just charge the lite weight battery. Has anyone out there ever used J3 cowl in this type of situation? Making a new modified nose-piece would be done if that would work.

Thanks
Jim Miller

Sounds like a great project.

First thing I would get rid of on your project is the 0-235. Those engines are expensive to rebuild and heavy for their power output. You might consider a hopped up 0-200 or even an 0-320.


That said, putting a pressure cowl on an lycoming or continental is not a problem. <-guess i missread your post.

The one thing you need to do is call your FSDO right now about an exp. There is something in the rules that after the first of the year you need to have the EW under a certain number to be in the LS category. I don't know much about exp, but that is one thing I would check into now.

Tim

Jim

An open cowl is quite popular within the Hatz Biplane community. If you look at the spacing between the cylinders on an 0-200 and an 0-235 you will see that the 0-235 cyls are very close together. This makes it difficult to get cooling air between the cyls in an open, non pressure cowl, type configuration. This results in uneven cooling and has resulted in more cracked cyls in the 0-235 camp Vs the 0-200 group. Also the starter ring makes the nose less attractive (in my opinion).





Hope this helps and just my opinion

Bill

Thanks
I will take a look at the Hatz cowlings. I may just go with a regular pressure cowl. I am committed to the 0235. The engine I have is on my Colt which I have just had rebuilt with new Lycoming cylinders and 50 hours since rebuild . It is running great. The 0235 with the new cylinders has a TBO of 2400hrs and is not that much more expensive to rebuild. The cylinders were maybe 150 to 200 more each than the 0320 but everything else was about same.

Jim Miller

I think you will have a real issue getting anybody to issue an AW for experimental/amateur built. Experimental/exhibition should be easy. Under 600 Horsepower you will no longer need a program letter. You will not qualify for a repairman's certificate to do your own condition inspection.
That said, If you are talking light: NO electrical system. Keep the extra seat but make it easily removable Only put in one set of controls. No interior. Partial floorboards. Leave the trim indicator out. Use the right fasteners. Don't use a longer bolt and add extra washers to make it work.
A skylight adds weight. Two toggle switches are lighter than a keyed ignition switch. Probably the lightest cover is Polyfiber with Polytone.
One nose tank will probably be your lightest fuel system.
Build to the 90% rule.

Everything weights something. A right angle tach drive weights 8 oz.
Building an airplane is like dieting. You put weight on in pounds and take it off in ounces.

Bill Rusk said:

Click to expand...

What a real beauty!

I think you'd be better going pressure cowl but the banner tow guys use a cowl like a J3 on Lycomings. I'd lengthen the ailerons to Cub size and modify the wings to accept them if it was me. The O-235 is a great engine and is lighter than the O-320 plus you have a good one.

You might try modifying the Colt wings as per Dave Blanton's Ford V6 STOL drawings. This involves clipping them where the spar caps start to taper and adding on about three feet of spar with aluminum angles.
The ailerons are lengthened to match.

I should wind up with 150 square feet of wing area. I'm using an 0200 with a pressure cowl

If weight is really a concern, I'd sell the 235 and use the money to buy an O-200 and install 10:1 pistons. You'll have about the same power with a lot less weight. Makes the J3 type nose easier too. for further weight savings, try titanium firewall, fittings, and controls.
JimC