Logo
Builders' Plan Gallery  |  Hip Pocket Web Site  |  Contact Forum Admin (Account/Technical Issues)  |  Contact Global Moderator
October 19, 2020, 04:52:57 PM *
Welcome, Guest. Please login or register.
Did you miss your activation email?

Login with email, password and session length
 
Home Help Search Login Register
Pages: [1] 2 3   Go Down
Print
Author Topic: Repairs  (Read 3728 times)
0 Members and 1 Guest are viewing this topic.
glidermaster
Gold Member
*****

Kudos: 19
Offline Offline

Canada Canada

Posts: 878


Topic starter


Ignore
« on: April 12, 2011, 09:34:14 PM »

The results of my last power flying session of last year can be seen here;
http://www.hippocketaeronautics.com/hpa_forum/index.php?topic=438.210

Now, onto some repairs;
Fuselage
The fuselage is basically a tapered box structure of 3/32" sheet with 1/8" sq. triangular longerons in the corners. As it crumpled rather than broke cleanly, all the members of the box need to be cut out and repaired at the damage site.

With a box it was easy to put it into 'splints' that re-establish square and true, temporarily gluing the least damaged side.

Then it was just a matter of working round the box splicing in new material.
Attached files Thumbnail(s):
Repairs
Repairs
Logged

Gliders are a part of me.
glidermaster
Gold Member
*****

Kudos: 19
Offline Offline

Canada Canada

Posts: 878


Topic starter


Ignore
« Reply #1 on: April 13, 2011, 12:11:34 AM »

Wing
The wing broke fairly cleanly right at the end of the dihedral braces. The spars are spruce and they couldn't be used to jig the wing back into position, nor could the trailing edge, which only left the leading edge. I strapped it to a piece of L section aluminium, on a flat board. As it was the left wing that broke, there were no warps to try and reset.

The spars were cut at an angle, outboard of the break, and new bits inserted from the centre section joint to the cut line. First the top spar, then the bottom. Next the broken trailing edge bits were cleaned up, and new material spliced in. With everything now straight, the leading edge break was cut out and new bits inserted. Additional material was glued on either side of the new joints in the spars. Lastly the leading edge sheet was restored.
Attached files Thumbnail(s):
Re: Repairs
Re: Repairs
Re: Repairs
Re: Repairs
Logged

Gliders are a part of me.
gossie
Platinum Member
******

Kudos: 50
Offline Offline

Australia Australia

Posts: 1,859



Ignore
« Reply #2 on: April 13, 2011, 01:01:08 AM »

What a wrecker you are. Man made, man can fix it though.

I had an Orca F1C a few years ago with a white painted fuselage and it got busted on the fuselage, and it got fixed as you have done.
Keeps us busy I suppose. Angry

I have always felt it's best to fix any damage that happens. That's why the current F1Cs, that you've seen go back so far and still fly okay..... well okay for me. Smiley
Logged
Scottl0413
Gold Member
*****

Kudos: 10
Offline Offline

United States United States

Posts: 313



Ignore
« Reply #3 on: April 13, 2011, 08:44:49 AM »

Very nice repair job. I had to do a similar repair on my Geodetic Galaxy last fall after the pilot messed up the launch. I used 1/64 ply to sandwich the spruce stringers back together and glassed the leading edge and trailing edge breaks. Seems to be very strong at this point. Have not had a chance to fly it yet!!

Scott
Logged
glidermaster
Gold Member
*****

Kudos: 19
Offline Offline

Canada Canada

Posts: 878


Topic starter


Ignore
« Reply #4 on: April 13, 2011, 11:05:22 AM »

Thank you Gentlemen!
When I get finished here, I still have to go back and find out what happened. I either did as Scott did with his model and launched very right tip down, or, more worrying, the auto rudder came in early - very early.

Anyway, last component to be repaired is the tail. At first sight it looked as if the tail was virtually unscathed, but closer investigation showed a very small compression failure in the upper main spar cap. Too small to take a meaningful picture of unfortunately. When I started cutting it out I managed to crack all the little 1/16" sq. spars in the leading edge!
Attached files Thumbnail(s):
Re: Repairs
Logged

Gliders are a part of me.
glidermaster
Gold Member
*****

Kudos: 19
Offline Offline

Canada Canada

Posts: 878


Topic starter


Ignore
« Reply #5 on: April 30, 2011, 01:10:18 PM »

All done, and ready to go again.
You can't even see the join - well, yes actually, you can!

A bit of accident investigation, and I've replaced the Seelig. I concluded that the auto rudder came in a few moments after launch because the timer arm hinge is very worn. Even though the arms have guards to stop them popping out at the wrong time, it still happened.

John
Attached files Thumbnail(s):
Re: Repairs
Re: Repairs
Logged

Gliders are a part of me.
glidermaster
Gold Member
*****

Kudos: 19
Offline Offline

Canada Canada

Posts: 878


Topic starter


Ignore
« Reply #6 on: August 22, 2011, 02:34:16 PM »

Just got back from Oregon, and the Vintage FAI Challenge. Had a great time, and Bob Stalick and co. got a real fun contest together. When I get a chance I will post a picture of the prettiest FAI Power model you will ever see - Bob De Shields '55 Gastove.

But, I have to repair Night Train again..............

She flew into some overhead lines that hit the wing tips, and peeled the wing off. Ho Hum!
Logged

Gliders are a part of me.
gossie
Platinum Member
******

Kudos: 50
Offline Offline

Australia Australia

Posts: 1,859



Ignore
« Reply #7 on: August 22, 2011, 06:35:20 PM »

Oh dear.  But fixing it will keep you out of the pub.   Grin

So how about that F1C.......I need to know how that beautiful thing went.  Come on, don't be shy.   I'm sure a couple of pics of it would not go astray either.
Logged
Ployd
Gold Member
*****

Kudos: 19
Offline Offline

Australia Australia

Posts: 302




Ignore
« Reply #8 on: August 22, 2011, 07:10:38 PM »

Pictures, we crave pictures especially Bob De Sheild's  '55 Gastove.

Ployd in OZ
Logged

"So I collect engines, what's your problem?"
glidermaster
Gold Member
*****

Kudos: 19
Offline Offline

Canada Canada

Posts: 878


Topic starter


Ignore
« Reply #9 on: August 23, 2011, 11:13:18 AM »

Ployd,
Have a look at the 'Nostalgia Gas Perfection' thread for the DeShields model.

The cameras were clicking with some frequency, and I know Bruce Hannah hangs out here from time to time, so hopefully, the pictures will appear presently.

In the mean time, pass the epoxy...............
John
Logged

Gliders are a part of me.
glidermaster
Gold Member
*****

Kudos: 19
Offline Offline

Canada Canada

Posts: 878


Topic starter


Ignore
« Reply #10 on: September 06, 2011, 11:59:05 PM »

Back to the Repair Station for Night Train.
I don't really mind crashing a model that's flying badly, but this one was annoying. A few inches lower and it would have glided past the power line or telephone line, or whatever it was, no problem. It would have DT'd 5 secs later.

Anyway, the fuselage kind of broke where it broke before, which says as much about LePages 5 minute epoxy as it does about anything else. I won't be using that again.

Here's a selection of pics. The fuselage is ready for paint, the wing's a little behind, but that wire put a pretty good slice into it.

John

Attached files Thumbnail(s):
Re: Repairs
Re: Repairs
Re: Repairs
Re: Repairs
Logged

Gliders are a part of me.
Pit
Palladium Member
********

Kudos: 132
Offline Offline

Germany Germany

Posts: 5,518


aka staubkorb


WWW

Ignore
« Reply #11 on: September 07, 2011, 05:18:07 AM »

It IS annoying when an adhesive dosn't do what it is suppsed to.  I banned  the so-called "5 minute Epoxys" TOTALLY from my inventory - even those from reputable companies.  I've not found ANY of them worth the money.  The 30 minute stuff  from WEST SYSTEMS, Pacer (Z-Poxy)  and Faserverbund Werkstoff Epoxyharz L (R&G GmbH) have been my epoxies of choice.
Logged

A Dedicated Convert to:
WWWoFF (Wonderfull Wacky World of Free Flight)

Comparing Spammers to a pile of organic waste is an insult to the organic waste!
gossie
Platinum Member
******

Kudos: 50
Offline Offline

Australia Australia

Posts: 1,859



Ignore
« Reply #12 on: September 07, 2011, 07:09:50 AM »

The wing will come together okay.   I've had them run into fences and get that sort of damage.  You just have to cut out the damage and replace it.

Re. the fuselage.   Have you thought about running a fine saw a couple of times lengthways on all four sides where the repair is and squeezing in thin but springy carbon strip about 1/8th wide then drop thin cyano onto it.   I've done that with 3 or 4 fuselages when the have either been broken or cracked at the rear.  They will never come apart again.
Logged
Zeiss Ikon
Gold Member
*****

Kudos: 10
Offline Offline

United States United States

Posts: 567




Ignore
« Reply #13 on: September 07, 2011, 07:11:54 AM »

I banned  the so-called "5 minute Epoxys" TOTALLY from my inventory - even those from reputable companies.

I completely agree.  There are two complementary problems with even the best 5 minute epoxy products.  First, it's hard to get a complete mix of resin and hardener quickly enough, and second, the working life after you mix is so short that it's difficult to get properly mixed epoxy into the joint and join the parts without "disturbing" partially set adhesive (very, very bad for the strength of an epoxy joint).  If the mix is bad, you'll get a joint with striations of glue that never hardens; if the joint is disturbed after the "pot life" has expired (which is typically less than three minutes after mixing is complete) the entire joint will be riddled with weakened adhesive.

What I'd really like to see is a "10 minute epoxy" -- faster setting than the usual 20 minute "mix and work" time for conventional epoxy, but without the "rush-rush-rush" pacing required with typical 5 minute products.  And no, you can't just mix conventional and 5 minute resins and hardeners to get that result -- that just produces a mess.
Logged

I'm here to have fun -- but winning isn't bad, either.
PeeTee
Titanium Member
*******

Kudos: 50
Offline Offline

United Kingdom United Kingdom

Posts: 2,309



Ignore
« Reply #14 on: September 07, 2011, 07:26:22 AM »

Quote
What I'd really like to see is a "10 minute epoxy

NHP used to produce a 12 minute Epoxy which was my favourite. I'm now down to my last inch in the 8 oz bottles,  NHP appears to have gone out of business and the retailers over here have sold all their stocks. I shall soon be trying out 5 minute Z Poxy and will let you know my views.

Peter
Logged
Tmat
Titanium Member
*******

Kudos: 69
Offline Offline

Canada Canada

Posts: 2,965




Ignore
« Reply #15 on: September 07, 2011, 07:42:03 AM »

3M make a very good epoxy called DP-100 which has a 5 - 10 minute working time. It's expensive, and I use the 50 ml cartridge tubes that fit into a dispenser gun (very handy but the tubes become pricey) but the epoxy is good stuff. DP-100 plus has excellent mechanical properties and DP-100FP is fire proof (!) and is my favorite right now (white in color).

Hardware store 5 minute epoxies are junk!

Tony
Logged

F1B guy...
But don't hold that against me!
glidermaster
Gold Member
*****

Kudos: 19
Offline Offline

Canada Canada

Posts: 878


Topic starter


Ignore
« Reply #16 on: September 07, 2011, 09:15:17 AM »

Some industrial supply chains carry a Devcon 5-minute epoxy that does at least go properly hard.
It's still a challenge to use, though as you effectively only have about 2 minutes - mixing very thoroughly is a must.

I did find a use for the LePages though when I fixed my wifes flip-flop. The rubberiness actually helps!

I hate those darned syringes they put the stuff in, too. What happened to good old tubes?

Fire proof epoxy eh, Tony?? Your models are that hot??

JB
Logged

Gliders are a part of me.
applehoney
Titanium Member
*******

Kudos: 279
Offline Offline

Canada Canada

Posts: 3,184




Ignore
« Reply #17 on: September 07, 2011, 09:53:16 AM »

The only epoxy I ever use now is Araldite ... the 24 hour variety.    I'm patient ...     and firewalls never pull out.
Logged
Tmat
Titanium Member
*******

Kudos: 69
Offline Offline

Canada Canada

Posts: 2,965




Ignore
« Reply #18 on: September 07, 2011, 10:42:18 AM »

Yeah, you might get going so fast the tiles come off! Grin

For all of my "serious" bonding I use 3M DP-460. Fantastic strength stuff.


Tony
Logged

F1B guy...
But don't hold that against me!
glidermaster
Gold Member
*****

Kudos: 19
Offline Offline

Canada Canada

Posts: 878


Topic starter


Ignore
« Reply #19 on: September 07, 2011, 11:18:49 AM »

When I got home from Tangent, the LePage disappointment fresh in my mind I did a simple test;
I cut some small coupons of thin alum. sheet (2024-T3 clad) and glued them to a scrap strip of the same material (just thicker) using
1) Araldite 24 hr which must be well over 20 years old.
2) Some 15 min. epoxy I picked up in the LHS (can't recall the make)
3) Some 1 hr epoxy inherited from my Dad so also over 20 years old
4) The dubious LePage 5 min.

The material was scrubbed with Scotch-brite, cleaned with soapy water, then rinsed and dried. Joints clamped and left in the basement workshop for about 30 hrs.
Araldite - excellent, I can't pull off the test coupon
15 min. good - but not fantastic
1hr - almost as good as the Araldite
LePage - marginally better than balsa cement.

My son, who thought I was being a total geek, thought saliva might have worked better than the 5 min. but suggested a re-test putting the joint in the sun to cure. Much to my surprise it worked much better, and actually went hard.

Not very good science, but interesting nonetheless.

JB
Logged

Gliders are a part of me.
gossie
Platinum Member
******

Kudos: 50
Offline Offline

Australia Australia

Posts: 1,859



Ignore
« Reply #20 on: September 07, 2011, 05:37:50 PM »

The only epoxy I ever use now is Araldite ... the 24 hour variety.    I'm patient ...     and firewalls never pull out.

Absolutely.
Logged
Dimeflyer
Platinum Member
******

Kudos: 55
Offline Offline

United States United States

Posts: 1,349



Ignore
« Reply #21 on: September 07, 2011, 07:33:41 PM »

Guys
if you want 5 min. epoxy to set up hard and strong you have to get it mixed exactly at 50/50 mixture
if you get just one molecule to much resin in the mix it will take for ever to harden if you get to much hardner
it may never finnish cureing !!
Just my experience in the past 40 or 50 years and it does not matter what brand it is guys !!
George
Logged
danberry
Gold Member
*****

Kudos: 17
Offline Offline

United States United States

Posts: 962



Ignore
« Reply #22 on: September 07, 2011, 07:48:41 PM »

Five-minute epoxy isn't good for anything that you need to rely on.
I don't think that it's even waterproof.
Logged
FF Bruce
Gold Member
*****

Kudos: 13
Offline Offline

United States United States

Posts: 486



Ignore
« Reply #23 on: September 07, 2011, 10:21:56 PM »

Ron Mc Burnett turned me on to Loctie 5 min. It takes a little longer than 5 min. to get hard,but if you have the time and let it set like 12 hours it gets very hard and sands like West Systems (which is my favorite epoxy of all time).
Logged
glidermaster
Gold Member
*****

Kudos: 19
Offline Offline

Canada Canada

Posts: 878


Topic starter


Ignore
« Reply #24 on: September 08, 2011, 12:10:38 AM »

George does make an interesting point, and is quite probably right.
It's tough to be precise, though, with the tubes, syringes or bottles they supply the stuff in, especially on the field.

I bought some of those little epoxy packs at the Dollar store (little syringe packs), and I must say they worked fine, although they were not used in a serious (i.e. f/f modelling) situation! Also, come to think of it, they were used out in the sun.

Also, the long cure glues don't seem to need that great a degree of precision.

No repair work tonight, I'm too pumped about flying Trad Lad  Cool

John
Logged

Gliders are a part of me.
Pages: [1] 2 3   Go Up
Print
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.21 | SMF © 2015, Simple Machines Valid XHTML 1.0! Valid CSS!