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-   -   162" Art Scholl Super Chipmunk (http://www.rcuniverse.com/forum/scratch-building-aircraft-design-3d-cad-174/10013518-162%22-art-scholl-super-chipmunk.html)

Thunderbolt47 09-19-2010 07:57 PM

162" Art Scholl Super Chipmunk
 
1 Attachment(s)
Hey Guys, Well I've been gathering info for sometime now. I have decided it was time to start the build. This build will be a slow one, as I'm still needing a few things.

This is my first scratch build and the first time I've ever worked from enlarged plans. The plans are the old Ohio RC plans (81") that where doubled. Power will be a DA-150 with cans if they can be made to fit. 12 servos should do the job. I will also have smoke. I'm estimating the weight around 60lbs.

I will be making a few mods from the plans. I'm not trying for perfect scale just going to try and get rid of the Sport scale look of the plans. The wings will be built as is. I've talked with several builders that say the wing is a good airfoil. I will be making it a three peice wing though. It will break at the ailerons.

The fuse will be rounded out. The Ohio kit had very flat sides and no wing fillets.

The first pic is of the main spar. It is two 1/4"x48" plywood.

Second is of the bottom spar. I cut a groove in it with my table saw. This will make the shearwebs stronger.

Pic three is of the lightning hole cut in to a 1/8" ply rib. There are only five of these.

Pics 4 and 5 are of the wing tube holes.

And finally the wing test fitted together. No Glue yet.

That is a 36" yard stick laying on the wing.

More pix later.
Kelly

Desertlakesflying 09-19-2010 08:46 PM

RE: 162
 
Oh I have to subscribe to this one.

jim52519 09-19-2010 09:34 PM

RE: 162
 
Kelly,
It looks good! It is larger than I thought it would be. I will be very interested in what you do with the fuselage.
Jim

jrbmoto 09-19-2010 10:52 PM

RE: 162
 
Beautiful!.....Looks like fun, cant wait for more pics!

-Johnny-

Thunderbolt47 09-20-2010 07:14 PM

RE: 162
 
1 Attachment(s)
Well today I got the rings doublers made and installed the right inner panel tube. I made a 1/8" ply pattern and used my router to cut out 4 at a time.

I'm using Titebond III. This seems to be some pretty good glue.

Later,
Kelly

flyguy 09-21-2010 05:29 PM

RE: 162
 
kelly those ribs look light with all of the lighting holes. Are you sure it will weigh sixty pounds?

Thunderbolt47 09-21-2010 07:29 PM

RE: 162
 
Hey Rick, I'm just guessing.[8D] It will be fully sheeted and glassed with paint. I'll say 60 so that way if it is lighter, that will be a plus. It will still have good performance even at 60lbs.

I have been weighing all the pieces that have been lightened. So far I've saved about 2.5 lbs. Most of that was plywood weight. Now I'm in the lite ply pieces, so there won't be much weight to lose.
Today I lightened some of the lite-ply ribs. So far on rib 7 I saved 1.2 ozs and on 8 about 1.5.( for both wing panels) As long as I can see a meaningful weight reduction, I will lighten more of the lite-ply ribs.

Later,
Kelly

Thunderbolt47 09-22-2010 09:01 PM

RE: 162
 
1 Attachment(s)
OK here todays progress.

I finally lightened all the ribs. In all I removed a 1/2 lb. That is for both wing panels. Didn't cut number 14. Every little bit adds up.

I have the lite-ply shear webs cut and they lock in place tight. Tomorrow after I sleep on it some, it will get some glue.

I did have to replace the inner rib 6. (that's the break) It was off just a tad. Didn't want it to bite me later. After some careful measuring I saw it was off more than I thought. Got to be more careful.[&o]

Later
Kelly

rgunder 09-26-2010 12:40 AM

RE: 162
 
Wow! Very impressive Kelly. I can't wait to see it complete. You say this is your first scratch build?

Thunderbolt47 09-26-2010 07:23 PM

RE: 162
 
1 Attachment(s)
OK hear's a photo flood. Got a lot done this weekend. I not going to give a blow by blow on this build, but if you see anything that raises a question, fill free to ask.

Kelly

Thunderbolt47 09-26-2010 07:28 PM

RE: 162
 
1 Attachment(s)
few more.

All Day Dan 09-26-2010 07:35 PM

RE: 162
 
Great job Kelly. What type of glue are you using to sheet the wing with? Usually, the water based glues set up too fast. Dan.

Thunderbolt47 09-26-2010 07:48 PM

RE: 162
 
I'm using titebond III. It seems to be work great and gives me a few minutes to get everything right.


Thunderbolt47 09-26-2010 08:17 PM

RE: 162
 

Quote:

ORIGINAL: rgunder

Wow! Very impressive Kelly. I can't wait to see it complete. You say this is your first scratch build?
Yes Rgunder, This is my first scratch build. I wanted something noone else had.:D

Thunderbolt47 09-28-2010 08:30 PM

RE: 162
 
1 Attachment(s)
Ok, I've been working on the left wing panel for the last few days, This is kind of like a re-run:)

I will post a few pics of how I make up my wing skins. MAybe this will be helpfull to someone. I learned this from Jack Devine's website years ago.

I don't trim my sheets. Most of the time you can turn the bow the same way and get a tight joint. Use masking tape to hold the sheets together. Flip the sheet over and hang them off the edge of the table. Add the glue to the joint that's open and move it up one sheet. As you do this the sheets on the table will lye flat, squezzing the excess glue out. Them wipe the excess off with a towel. Let it sit for a few hours and you have wing skins.

A good friend of mine gave me a great tip. Sand the sheet joints smooth on the table, because it's easier and you get better results than sanding after it's applied.


Last couple of pics is of the wing assembled. The table it's on is 11 feet long.
Later,
Kelly


BMatthews 09-28-2010 10:29 PM

RE: 162
 
Just when I think we're doomed to drown in a sea of ARF's someone like you comes along with a project like this. It's enough to restore one's faith in the human spirit!

Like the others I'll be watching along with intrest and enthusiasm.

flyguy 09-29-2010 04:45 AM

RE: 162
 
Looks like you need a larger table, and a larger shop.The wing is looking good.

gene6029 09-29-2010 04:59 AM

RE: 162
 
Im following along w everyone too! I think this is a great project & look foreward to each post you make. Keep up the excellent work....Gene;)

R_G 09-29-2010 07:47 PM

RE: 162
 
Very nice build you've got going here Kelly! [sm=thumbs_up.gif] I especially like the fact that you're cutting out all of your own parts instead of using laser fried parts! Although they can be very accurate I don't care for the look of the burnt edges of laser cut wood!

Looking forward to seeing more progress!

RG

Thunderbolt47 09-29-2010 08:51 PM

RE: 162
 
Thanks for all the compliments guys. I'm having FUN!

Hey Flyguy, I added on to my table just for this build. I won't be able to put this plane together in my shop, But at least I won't have to tear a wall down to get it out. LOL

Later,
Kelly



winglift 09-30-2010 07:42 PM

RE: 162
 
Wow! It looks like quite the project, very impressive so far. Keep up the good work. I was thinking about doing a scratch build myself and was wondering how you cut the ribs?

Thunderbolt47 10-01-2010 08:47 PM

RE: 162
 
1 Attachment(s)
Hey Winglift, Here is what I used to attach the templet to the wood. Just give it a light pass and it sticks pretty good. Seperation is easy and the adhesive isn't noticable on the wood afterwards. You can stack as many sheets as you need. I had to make two of each rib.

Also, 3M makes #77 spray and I found some really cheap stuff the other day for $4 a can but haven't tried it yet. I believe the NAPA spray was $10.

Hope this helps,
Kelly

Thunderbolt47 10-01-2010 09:19 PM

RE: 162
 
Here is my motivation, It keeps me going:D


http://www.youtube.com/watch?v=A-kHTmYjBQk

jim52519 10-01-2010 09:40 PM

RE: 162
 
Kelly,
I too found this Art Scholl video inspiring! Art was quite a showman. I plan to start my 50 cc version of the Chippy next spring after I finish my Extra.
Jim

andrew66 10-03-2010 01:13 AM

RE: 162
 
very nice work! One technique i was shown for making wing skins, is to join the sheets of balsa with contact cement. Works pretty good and is a fairly quick procedure providing that the sheets are all lined up and fitted properly.


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