Dave Smith/Tom Martin 1/4 Scale Hall Cherokee Build

[jmears]

Art -

I'm really enjoying your build. Great work!
If we all make it to Huntsville in October there should be five Cherokees on the field. Should make for a cool group picture. - John

[ingrahal]

Thanks John, I'm glad you're enjoying the build. I'll do my best to be at the Huntsville event.

[ingrahal]

Ok here is a better photo. Stew caught the mistake. The wire loop should be flat against the nose former. Basically sandwiched between it and the 1/8" ply mount. I'm sure it will function ok it just looks a little goofy.

[Dave Smith]

Art, sorry I missed your earlier question about nose weight. I waited (pun intended?) until I had the wings built and everything framed up, then balanced it like that, knowing that there would be a small amount of additional nose weight required once the plane was covered and control runs, etc. were completed. This will get you close. Don't forget your pilot if you are using one. Once everything is finished, then add final touch balancing weight on the front of the battery tray. I have kept my battery tray removable so it is easy to pull it out and adjust weights as required.

I did make a bit of a mistake recently with my 1/4 scale version; added larger (heavier) batteries and ended up not being able to get my balance back as far as I would like without removing the pilot. All I'm saying is, don't go overboard on the permanent weight because you can usually sneak a bit of extra on the battery tray if you need it and that will keep things flexible.

Dave

[ingrahal]

Ok thanks, I would think you could sneak some in below the tray too if need be. I think I had read on one of the other build threads that a certain amount of permanent weight was suggested to be added to the floor in the nose before covering.

[ingrahal]

Update time:

I got the tow release servo mounted and then decided to tackle the canopy. I might as well get it done and then the hardest part of the build will be behind me.

Here are a few shots of the tow release servo.








Update continued on next post.

[ingrahal]

Update continued:

Forming the canopy bow with strips of 1/32" fir.






Update continued on next post.

[ingrahal]

Update continued:

I wanted to share a little trick I use when I need to remove a very small amount of material when fitting a piece.

Use the tip of your mechanical pencil like this to make an even pencil line on the edge of the piece.


Then sand away all but a tiny bit of the pencil line. Repeat as necessary to achieve a good fit. I used my 12" disc sander on this one.


Gluing up the canopy frame.


Very fragile at this point.


Continued on next post.

[ingrahal]

Update continued:

Gussets added to reinforce the frame.


Cutting out the center.


Canopy frame is finished.


That's it for now. This is next. :-(

[ARUP]

Art, your Cherokee is really coming along. I would sure like to have mine ready for October!

[ingrahal]

Thanks Michael, I had a little bit of an interruption last week. A longtime friend came to visit and we spent three days on the Little Red River fly fishing. I used to guide and he is just getting into it so I was able to help him get started on the right foot. We had a blast!!! Now it's time to get back to work on the Cherokee. Especially now that the high temperatures are in the upper 90's here in Arkansas.

Are you going to start yours soon? If so I'll get you a canopy in the mail.

[ingrahal]

Update time:
I've been working on the canopy form. I used up almost all of the block balsa in the shop to extend the form. Then many coats of putty and sanding.

Here is the form with a pull of styrene over it.


I got a decent pull on the first try.


It's not perfect but I think it will work. This form should work for both the standard canopy and the extended one.


I'm sure glad to get that done. The rest of the build should be pretty straight forward. I'll move on to the tail section next. I want to get as much done as possible while it's still sitting flat on the bench, then do the bottom keel last.

[Swiss1]

What thickness material did you use for the canopy?

Jeremy and Ben
SCC AAA TT TN

[ingrahal]

It's 0.030" PEG. I might have to go to 0.040" as one side feels a little thin. On my vacuum machine the material swings onto the form from one side in an arc. This means the heated material has to stretch more on one side and is therefore thinner on that side. On small items it's not a big deal but on large ones it can be a problem. I would like to redesign it so the material comes straight down on the form.

[ingrahal]

Update:

Got the rudder framed up.


Everything looks nice and straight.


Moving on to the H. Stab, elevator, and stab mount.

[lenb]

Really nice work Art,very impressed with the build.

[ingrahal]

Thanks Len that means a lot to me!!!

[ingrahal]

Update:

I'm making progress on the stab and elevator.

First I cut and shaped the stab TE and elevator LE. There is a discrepancy on the plans. The note here calls for 1/4" stock but the drawing shows 3/16". I had ordered 3/16" and went with that.


I used 3M Super 77 to temporarily glue the two pieces together and shaped them both a once.






continued on next post.

[ingrahal]

Continued from previous post:

I made up a bunch of these clamping squares of various sizes. Something I learned from my Dad working in his cabinet shop. They are easy to make and I use them all the time. Notice the beveled corner that prevents the square from being glued to the work.




Not quite done but I ran out of steam. The sheeting and shear webs make the assembly extremely rigid.


Some cap strips, balsa tips, and the control horn and this will be done.

[ingrahal]

Update:

The H. stab and elevator is done.

I made the control horn per the plans.






Continued...