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Outdoor Free Flight Forum => Power => Topic started by: glidermaster on April 12, 2011, 09:34:14 PM



Title: Repairs
Post by: glidermaster 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.


Title: Re: Repairs
Post by: glidermaster 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.


Title: Re: Repairs
Post by: gossie 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. >:(

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. :)


Title: Re: Repairs
Post by: Scottl0413 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


Title: Re: Repairs
Post by: glidermaster 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!


Title: Re: Repairs
Post by: glidermaster 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


Title: Re: Repairs
Post by: glidermaster 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!


Title: Re: Repairs
Post by: gossie on August 22, 2011, 06:35:20 PM
Oh dear.  But fixing it will keep you out of the pub.   ;D

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.


Title: Re: Repairs
Post by: Ployd on August 22, 2011, 07:10:38 PM
Pictures, we crave pictures especially Bob De Sheild's  '55 Gastove.

Ployd in OZ


Title: Re: Repairs
Post by: glidermaster 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


Title: Re: Repairs
Post by: glidermaster 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



Title: Re: Repairs
Post by: Pit 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.


Title: Re: Repairs
Post by: gossie 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.


Title: Re: Repairs
Post by: Zeiss Ikon 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.


Title: Re: Repairs
Post by: PeeTee 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


Title: Re: Repairs
Post by: Tmat 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


Title: Re: Repairs
Post by: glidermaster 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


Title: Re: Repairs
Post by: applehoney 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.


Title: Re: Repairs
Post by: Tmat on September 07, 2011, 10:42:18 AM
Yeah, you might get going so fast the tiles come off! ;D

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


Tony


Title: Re: Repairs
Post by: glidermaster 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


Title: Re: Repairs
Post by: gossie 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.


Title: Re: Repairs
Post by: Dimeflyer 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


Title: Re: Repairs
Post by: danberry 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.


Title: Re: Repairs
Post by: FF Bruce 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).


Title: Re: Repairs
Post by: glidermaster 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  8)

John


Title: Re: Repairs
Post by: sweepettelee on September 12, 2011, 12:40:13 PM
Your wish is my command, Bobby DeShields beautiful Gastove!
Imagine how great it looks in person!
Pix taken at Tangent OR, during NWFFChamps.
GM John's admiration of Gastove is my feeling as well.
Only THE most graceful and best-looking FAI Power model ever!


Title: Re: Repairs
Post by: applehoney on September 12, 2011, 01:32:23 PM
Yeah .. .but you should have seen the big Hornet .60 version !         ;D


Title: Re: Repairs
Post by: glidermaster on September 12, 2011, 05:58:31 PM
Jim's right, see for yourself  :D


Title: Re: Repairs
Post by: gossie on September 12, 2011, 06:00:50 PM
Yeah .. .but you should have seen the big Hornet .60 version !         ;D

Yeah, but who has a plan?   Have a pic of it on the old Aeromodeller mag. and no doubt it would be some machine.   Did you see it fly Jim?

The FAI Gastove is indeed a beautiful build.    I always thought them a little small for an Oliver Tiger though.   But no doubt Michael Gaster knew best.


Title: Re: Repairs
Post by: glidermaster on September 13, 2011, 02:04:05 PM
Lee's got a good eye.

I think it's time we got the Old Leeper building power models again - it must be 50 yrs since your Ramrod days, eh, Lee??

Gastove is way better looking than Ramrod.


Title: Re: Repairs
Post by: RobinB on February 03, 2013, 07:16:46 AM
Latest edition of the Clarion at www.SAM1066.org

has a picture of Mike Gaster (with Vic Jays) holding a later Gastove.


Title: Re: Repairs
Post by: gossie on February 03, 2013, 06:38:50 PM
Latest edition of the Clarion at www.SAM1066.org

has a picture of Mike Gaster (with Vic Jays) holding a later Gastove.

The last Clarion I seem to be able to get is January and Gaster and Jays are not in that.   Guess you mean February??????


Title: Re: Repairs
Post by: glidermaster on February 03, 2013, 08:36:15 PM
??
Click on Robin's link, look on the left for the 'New Clarion' item on the left split screen column, which has February flashing away rather gawdily, then 'February 2013' is right there, top left of the main screen.

Works OK in this former colony.

John


Title: Re: Repairs
Post by: gossie on February 03, 2013, 10:25:53 PM
I can see February JB, but have clicked on that for two days now and all I get is January coming up. 


Title: Re: Repairs
Post by: Ployd on February 04, 2013, 03:25:43 PM
Hi Gossie

Click on the word "February" to get the down load of the Clarion then go to page 40.
In the meantime here is the pic you want.

Ployd in OZ


Title: Re: Repairs
Post by: glidermaster on February 04, 2013, 03:48:33 PM
1965 Gastove, home made engine, and hand carved propellers.

Not many people have qualified for a World Champs with an engine they built themselves.
Mike is quite the craftsman!


Title: Re: Repairs
Post by: gossie on February 04, 2013, 04:33:16 PM
Yep, got it.   Guess it just takes longer to get down here.  It sure would not work though up to last night when I took a quick look.


Title: Re: Repairs
Post by: glidermaster on August 30, 2013, 11:52:09 AM
Darn it, Night Train's back in the repair shop!


Title: Re: Repairs
Post by: FF Bruce on August 30, 2013, 08:54:38 PM
John, Sorry about your Train,but I know you can make it better, faster & stronger than before.Or was that the $6,000,000 model oh well good luck on your repair


Title: Re: Repairs
Post by: glidermaster on September 19, 2013, 01:10:59 PM
A little update;
The tail is repaired and covered - I used lightweight Polyspan - I love this stuff! goes on easy, shrinks up wrinkle free, easy to dope, it's great :)

Not much point putting up a picture of a white tail, though - I'll be using lightweight Esaki for the colour trim, and I think I have just enough Tufkote left to fuel proof it. Boy I need to find some more of that, or a decent substitute.
John


Title: Re: Repairs
Post by: john thompson on September 20, 2013, 03:52:20 AM
Rustins plastic coating, a two part item that is used for furniture /interior wood work , is what I use . Leave for 5 days or so for it to harden properly . It withstands 50% nitro OK . I would expect any similar products possibly more available across the Pond, would probably do the trick . www.rustins.co.uk. john


Title: Re: Repairs
Post by: glidermaster on October 14, 2013, 06:39:41 PM
Well, the fuel proofer issue is still not solved, but Night Train is about clear of the repair shop.
The tail is done, and as I inspected the rest I found a compression mark in the rear fuselage, where it had broken before - also, I am sure, a result of coming down on those motor bike handlebars.
I dressed off the area around the damage with a sanding drum in the Dremel, then layed a few strands of carbon across the damage, then built up a multi-layer glass fibre/epoxy patch. A little paint, and it'll be complete.
This model is just about to go back in the box, hopefully to take the air again at Lost Hills in Feb. - work, money and opportunity permitting!

John


Title: Re: Repairs
Post by: glidermaster on August 08, 2016, 08:01:29 PM
I've spent quite a lot of time recently repairing models, both rubber and power.

2 years ago it took less than 10 seconds to turn my G15 powered George Fuller 'Trad Lad' into a 'Sad Trad Lad'.

Yesterday it went into the queue for fuel proofer. August in Tangent here we come!

John


Title: Re: Repairs
Post by: RobinB on August 11, 2016, 05:21:17 PM
Has it got any heavier after repairs, John?  ;D

Robin


Title: Re: Repairs
Post by: glidermaster on August 11, 2016, 07:07:02 PM
Yes Robin, a little bit.
But it was underweight when built anyway, so I just removed the ballast. Not a problem really.

JB


Title: Re: Repairs
Post by: glidermaster on September 25, 2016, 10:44:28 PM
The Repair Shop has been busy again........


Title: Re: Repairs
Post by: gossie on September 26, 2016, 01:28:59 AM
Looking good.   Now just be more careful. ;D


Title: Re: Repairs
Post by: RobinB on September 26, 2016, 11:31:42 AM
This one's more of a replace rather than a repair.

Robin


Title: Re: Repairs
Post by: glidermaster on September 26, 2016, 06:29:57 PM
Ouch Robin!
What happened?

(Agreed, replace rather than repair).


Title: Re: Repairs
Post by: gossie on September 26, 2016, 07:41:36 PM
You could probably use the tips?????????????????


Title: Re: Repairs
Post by: RobinB on September 27, 2016, 09:01:17 AM
It was over a year ago.
It was on trim and going well, until I did my first official flight!
The familiar intermittent problem with a gravity (tank) system - it missed momentarily just after launch.
Usual sequence followed:- nose drops, wings come level, resumes spiral climb.
On this occasion it stopped while nearly inverted - not good.
At least it missed the tarmac.

The fuselage is ok. I'm going to remove the tank, though.
I may not build any more SLOP aeroplanes, thus avoiding any further episodes like this.

Robin
 


Title: Re: Repairs
Post by: glidermaster on October 05, 2016, 04:10:16 PM
I had mixed results from the repaired models in reply #45; the elliptical tipped 1/2A Train needed no further trimming, and flew well last weekend in Oregon.
The 15 model was not so fortunate. Thinking I had a fairly stiff wing, I didn't jig it in position during doping and the result was that wash-in crept in on the LH inner panel. Fortunately it was not bad enough to cause a crash.

I will try and straighten it out by steaming, and then leave it on a board held to the right shape for a few weeks and see what happens.

JB