HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Jun 05, 2009, 05:32 AM
Promoting Model Aviation...
Murocflyer's Avatar
United States, CA, Tehachapi
Joined Nov 2005
24,772 Posts
EJ,

Looking great! And a great build thread also. Lots of detail and great photos. I'm rating it 5 stars. (not many folks rate threads these days)

Frank
Murocflyer is online now Find More Posts by Murocflyer
RCG Plus Member
Sign up now
to remove ads between posts
Old Jun 05, 2009, 12:01 PM
AMA 910957
EJWash1's Avatar
United States, WA, Hoodsport
Joined Mar 2008
5,221 Posts
Frank,

Thank you! I appreciate your rating.

It's a fun build.

EJWash
EJWash1 is online now Find More Posts by EJWash1
Reply With Quote
Old Jun 05, 2009, 08:50 PM
AMA 910957
EJWash1's Avatar
United States, WA, Hoodsport
Joined Mar 2008
5,221 Posts
The wing doubler and filler stayed in the clamps overnight. When I removed them I took a moment just to look at the wing and say: “ahhh.” Now it looks like the beginning of a flying machine.

A 1/8” plywood plate (P2) is bonded to the doubler and filler piece. P2 will rest against the fuselage former (P1) to hold the leading edge of the wing in place.

I noticed a problem with P2 when I put it in place. Although the top of P2 spanned the top width of the area of the wing mid-section, the bottom did not (see pic). There were gaps between the bottom edges of P2 and the wing rib. I measured and re-measured the entire wing to make sure that it was square. Then I became mad at myself for not checking measurements and square before I joined the wing panels to the wing mid-section. I must have goofed somewhere, but where?

The “you dummy” light finally came on when I squatted down and looked at the wing. THE DIHEDRAL!!! In case I didn’t mention it, the wing mid-section is flat, and the wing panels are at a 2-1/2 degree dihedral angle to it. Of course, this includes the inner wing ribs, thus the gaps at the bottom of P2, which has square sides all around. Since the kit supplied P2 did not span the bottom of the wing mid-section, I cut a replacement. Nice and snug now.

EJWash
EJWash1 is online now Find More Posts by EJWash1
Reply With Quote
Old Jun 06, 2009, 11:57 PM
AMA 910957
EJWash1's Avatar
United States, WA, Hoodsport
Joined Mar 2008
5,221 Posts
Snuck a little time on the Citabria today.

Installed the wing mounting filler blocks. Trimming cut was made with a Japanese cross cut saw. Very sharp and cuts on the draw. Knock the blocks down further with the 80 grit sanding bar, and then flush with 150 grit.

Next, the issue of the wing strut mounting came up. Sig notes that the struts are in-fact function on this model. There are four 1/2” X 1/2” squares of 3/32” ply glued adjacent to depicted ribs on the plan sheet. The struts are held in place with #2 3/8” long sheet metal screws. Being that I will be removing the wing, therefore the struts, for travel and storage of the model, I didn’t see the integrity of this method lasting very long.

What I came up with will penalize me about four grams in weight, but I didn’t thing that I will have to be concerned with the struts pulling from the wing or wearing out the plywood mount with the sheet metal screw.

I’m using 1/4” thick basswood cut to 5/8” X 3/4”. There is a 4-40 blind nut counter-sunk in the middle of it. The mount will be epoxied to the lower internal wing strut and plan depicted rib, and the aileron spar and rib. I cut 1/16” caps to cover the basswood mount to bind the basswood mount to the spars, and to hold the blind nut in place so it does not pop-out of it’s hole.

Thanks for following along!

EJWash
EJWash1 is online now Find More Posts by EJWash1
Last edited by EJWash1; Jun 07, 2009 at 12:09 AM.
Reply With Quote
Old Jun 07, 2009, 05:44 AM
Hamburger Eatin' Fool
TomCrump's Avatar
Traverse City, Michigan
Joined Dec 2005
11,141 Posts
Good thinking, on the strut mounts. Even the best kits contain design flaws. Ypu were smart to take care of this one.
TomCrump is offline Find More Posts by TomCrump
Reply With Quote
Old Jun 07, 2009, 06:56 PM
AMA 910957
EJWash1's Avatar
United States, WA, Hoodsport
Joined Mar 2008
5,221 Posts
Tom,

I didn't think that the design considered attaching and removing the wing every flight period. The kit plan may work if the struts are not removed at the outer wing location. The strut attachment at the fuselage use nylon clevises. I guess the intent was that the wing would only have to be periodically removed. And, if/when the wing is removed, the wing struts are removed at the fuselage only, and not the outer attachment. Which means the wing will have to be transported and stored in the flight position. Not good.

In modifying the wing strut mounts, I considered two main things:

- suffer a few grams now and build a more secure mounting platform

- or -

- revisit the situation after failure and suffer the added weight of rebuilt mounts then.

Of course, the rebuild after failure would more than likely involve more than reconstructing wing strut mounts...

EJWash
EJWash1 is online now Find More Posts by EJWash1
Reply With Quote
Old Jun 07, 2009, 09:25 PM
AMA 910957
EJWash1's Avatar
United States, WA, Hoodsport
Joined Mar 2008
5,221 Posts
Nothing to log today, the weather was way too nice to stay in.

Hit the lake to stay cool...

EJWash
EJWash1 is online now Find More Posts by EJWash1
Reply With Quote
Old Jun 08, 2009, 06:20 AM
Hamburger Eatin' Fool
TomCrump's Avatar
Traverse City, Michigan
Joined Dec 2005
11,141 Posts
Cool ??? You want cool?

Pay me a visit. The high will be 60 today !!!

I was thinking that I should head out your way !!!
TomCrump is offline Find More Posts by TomCrump
Reply With Quote
Old Jun 13, 2009, 12:10 AM
AMA 910957
EJWash1's Avatar
United States, WA, Hoodsport
Joined Mar 2008
5,221 Posts
Got a little work in on the wing strut mounts. I feel pretty good about the mounts being durable for strut attachment and removal for transport.

The bottom leading edge of the wing was sheeted.

I also did some work on the ailerons, but nothing really photo worthy.

Thanks for following along!

EJWash
EJWash1 is online now Find More Posts by EJWash1
Reply With Quote
Old Jun 13, 2009, 01:22 AM
AMA 910957
EJWash1's Avatar
United States, WA, Hoodsport
Joined Mar 2008
5,221 Posts
Quote:
Originally Posted by TomCrump
I was thinking that I should head out your way !!!
You'd melt!

Actually, we've been smiled upon so far. Nothing over 110F yet!

EJWash
EJWash1 is online now Find More Posts by EJWash1
Reply With Quote
Old Jun 13, 2009, 06:43 AM
Hamburger Eatin' Fool
TomCrump's Avatar
Traverse City, Michigan
Joined Dec 2005
11,141 Posts
It's finally warming up, here, EJ. It hit 70, yesterday. LOL
TomCrump is offline Find More Posts by TomCrump
Reply With Quote
Old Jun 13, 2009, 08:55 PM
AMA 910957
EJWash1's Avatar
United States, WA, Hoodsport
Joined Mar 2008
5,221 Posts
Sig includes and instructs that the leading edge bottom and top of the wing is sheeted with 1/16” X 2” balsa. 2” works great with the bottom sheeting, but on dry fitting the top sheeting, the 2” doesn’t stretch all the way to the end of the top wing spar. The sheet comes up about a 3/32” short. I replaced the top sheeting with 2-1/4” wide sheeting stripped down from 3” stock.

As shown previously, I applied the leading edge bottom wing sheeting using Titebond and pinning the sheeting into position for drying. Time consuming to say the least. Not only that, it’s hard to pin down the edges of the sheeting along the top and bottom spar.

Last night, I remembered reading another method of applying wing sheeting (WHY didn’t I remember this before I applied the bottom sheeting??? Arg!).

The technique comes from a book from Model Airplanes News’ “Radio Control Airplane Building Techniques” by Randy Randolph.

Elmer’s, Tiebond, or any white glue is used (Titebond for me). A thin layer of glue is applied to the surfaces of the wing that will come in contact with the sheeting, and on the sheeting in the area that will contact the wing. The glue is allowed to dry (:30 in minimum) to the touch. The sheeting is then “ironed-on” using a clothes iron set to wool. The heat causes the glue to polymerize. Not sure if you can use a covering film iron or not.

I wanted to try a test piece, so I brushed-on Titebond on a 3/32” X 1/2” strip and a 1/4” square stick, both about 5” long. I used an old non-steam travel iron and bonded the two pieces together and set it aside to cool. Yep, it bonded alright!

Applying the top sheeting to the wing went smoothly. No pins, no pins holes. A much less intrusive method! I’ll be applying the cap strips the same way.

Thanks for following along!

EJWash
EJWash1 is online now Find More Posts by EJWash1
Last edited by EJWash1; Jun 13, 2009 at 09:04 PM.
Reply With Quote
Old Jun 13, 2009, 11:36 PM
Hamburger Eatin' Fool
TomCrump's Avatar
Traverse City, Michigan
Joined Dec 2005
11,141 Posts
Nice, EJ.

I like your sheeting technique.

While you were in the shop, I was outside enjoying our beautiful 75 dgree weather. There was no wind. A great day for flying !
TomCrump is offline Find More Posts by TomCrump
Reply With Quote
Old Jun 14, 2009, 12:41 AM
AMA 910957
EJWash1's Avatar
United States, WA, Hoodsport
Joined Mar 2008
5,221 Posts
Thanks Tom.

The neat thing about the iron-on technique is that you can position the sheeting on the wing and make adjustments before you iron it down. This is 1/16" sheeting. I'm sure it would take a bit more time and passes with the iron on 3/32" sheeting.

I pulled my test piece apart. Of course, the wood failed and not the joint.

Great pic of you there! Catches you in the essence of the hobby: relaxed.

Stopped by the SW thread. Glad that you got to run the engine. Does it purr? Gonna take her up next week?

Not sure if I told you that I have a NIB OS Gemini FT-120. I take it out and just look at it now and then. Not sure If I'll ever put it in anything, it's too gorgeous!

EJWash
EJWash1 is online now Find More Posts by EJWash1
Reply With Quote
Old Jun 14, 2009, 06:17 AM
Hamburger Eatin' Fool
TomCrump's Avatar
Traverse City, Michigan
Joined Dec 2005
11,141 Posts
You haven't mentioned the 1.20 before, EJ. The motor was made to run, so run it !!!

A friend has a Sig 1/4 clipped wing Cub, powered by the same motor. It's a perfect combo for relaxed aerobatics.

Ya, my Magnum twin sounds sweet !!!

Since early retirement, being relaxed has been the mainstay of my existence. LOL I recommend that you join me as soon as possible !
TomCrump is offline Find More Posts by TomCrump
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion SIG 1/5 scale Cub MJFinegan Glow to Electric Conversions 14 Jun 08, 2007 09:20 AM
For Sale Sig 1/6 scale Citabria kit. Gerald Aircraft - Fuel - Airplanes (FS/W) 1 May 28, 2006 04:34 PM
Sig 1/5 scale Piper Cub Michael in Toronto Scale Kit/Scratch Built 5 Oct 04, 2002 11:30 AM