Author Topic: Damage Repairs to the Paradigm (Read 8923 times)

john ohnimus · « **on:** August 09, 2015, 07:53:26 PM »

So I have begun repairs to a stunt ship I bought from Ken Grasser many many moons ago. I had got some serious hangar rash along with the empennage broken off by the cable guy at some point over the last 16 yrs. I hope to get some advice from the guys on the forums here and return this fine ship to its former glory.

Randy Powell · « **Reply #1 on:** August 11, 2015, 11:27:34 AM »

What do you need to know?

john ohnimus · « **Reply #2 on:** August 11, 2015, 01:09:12 PM »

Not sure yet.. Gonna get the tail put back together and then on to repairs to the finish. I am gonna need to know a good way to repair the open bays on the wing and stab. So far I have removed the damaged tissue and done some light sanding with 320 grit. I believe if I use some thinner I can "melt" the old finish enough to place the repair pieces over the open bays. Any thoughts on that procedure?

Randy Powell · « **Reply #3 on:** August 11, 2015, 02:45:48 PM »

Well, in repairing the tail, make sure you jig it up as straight as possible. You can use some plywood inserts to strengthen the area. On the wing areas, sand the edges and apply a silkspan patch (if you can some) or possibly silk material. Build up some substrate with clear dope and filler coat then use sandpaper to blend it into the surrounding area and repaint. But a lot of that depends on what was used in the original finish. For instance, if Aerogloss was used, there is almost nothing compatible with that. If Sig or similar dope, then it's pretty easy. And you will have to figure out what original colors were used to match what is there.

I have a Cobra in much the same shape and I'm trying to decide if it is worth fixing.

john ohnimus · « **Reply #4 on:** August 11, 2015, 10:03:11 PM »

Mr. Grasser was kind enough to give me some of the color he had mixed for the airplane when originally finished it. Sig product if I remember correctly. I though I had tossed it out and found it in a box last weekend. I went ahead with a few patches to the open bays on the bottom of the wing this evening and everything is working well. I have to get a decent brush tomorrow so I can start with the clear. I will post pics tomorrow before I get to far along. Gonna focus on the tail this weekend and get the airplane in " Jig Position " as we call it in commercial aviation. I should then move forward with that repair.

john ohnimus · « **Reply #5 on:** August 12, 2015, 05:52:32 AM »

A picture of the bottom of the wing..

Larry Fruits · « **Reply #6 on:** August 12, 2015, 07:42:13 AM »

Hi John,
Looks like the repairs are coming along nicely. If you tear the edges of the silkspan patches rather than cutting them as it appears in the photo, it will be easier to feather the edges to the surrounding area. In fact they will all but disappear with a light sanding after doping them down, and then be gone after finish doping.
Looks great and keep up the good work.

Larry

john ohnimus · « **Reply #7 on:** August 12, 2015, 08:53:59 AM »

Thanks to all for the advice. I do remember now hearing/reading about tearing the edges of the silks pan to more easily blend the repair in. I will definitely utilize that method on the top of the wing as I have several open bays that need repairs. I will keep at it. Trying to be ready for the Huntersville contest in October!!!

john ohnimus · « **Reply #8 on:** August 12, 2015, 08:59:10 AM »

Another aspect is matching the lettering on the wings. I will have to research that to see if a matching font can be found. I would hate to have to remove the lettering and then reapply it. I saved some of the torn tissue so I can match the colors. Any good ideas on that??

Randy Powell · « **Reply #9 on:** August 12, 2015, 10:51:26 AM »

Larry, good point on tearing the edges. Forgot to include that.

On the lettering. matching may be tough. It looks like it was airbrushed. You may have to come up with vinyl masks and reshoot all the lettering. Not terrible, but time consuming.

john ohnimus · « **Reply #10 on:** August 12, 2015, 11:32:29 AM »

Its definitley a stencil. You can just feel the raised edge where the mask was. I may try to print a pic of it and take it to KINKOs to see if they can match the font. If I have to redo the lettering, is there a good way to remove the current lettering or am I going to have to sand it all off?

Randy Cuberly · « **Reply #11 on:** August 12, 2015, 03:07:07 PM »

Quote from: john ohnimus on August 12, 2015, 11:32:29 AM

Its definitley a stencil. You can just feel the raised edge where the mask was. I may try to print a pic of it and take it to KINKOs to see if they can match the font. If I have to redo the lettering, is there a good way to remove the current lettering or am I going to have to sand it all off?

If you intend to repaint the entire wing then you can most likely just wipe it with thinner and paper towels, small areas of a few square inches at a time, then re-spray with several coats of clear then color and then paint the lettering with a mask. Only caution is to use thinner not acetone even though it's tempting. The acetone dries too fast and is very hard to get off before it gums up again...trust me, I know this first hand!

Randy Cuberly

Larry Fruits · « **Reply #12 on:** August 12, 2015, 04:55:05 PM »

Quote from: Randy Powell on August 12, 2015, 10:51:26 AM

Larry, good point on tearing the edges. Forgot to include that.

]

Thanks Randy. It's easy to forget some of the smaller steps, especially when you do them out of habit many times, as I am sure you have done.

Looks like John is doing a great repair on a fine looking plane. I am betting it will be hard to find the repairs after he is finished.

Larry

Randy Powell · « **Reply #13 on:** August 12, 2015, 08:15:02 PM »

I'm more worried about the tail than patching the wing. That damage looks nasty.

john ohnimus · « **Reply #14 on:** August 12, 2015, 10:11:11 PM »

Thanks again!!! The wing repairs are moving along smoothly and I will likely start the top of the wing tonight. The repairs to the tail will begin this weekend and I will be getting this thing level and square to the table. I have so me slow epoxy I plan on using, and a stragedy for reinforcing the structure. Once again I will kept you guys posted and put up some pics as I progress.

Tony O

Steve Helmick · « **Reply #15 on:** August 13, 2015, 04:59:01 PM »

I think I would be fitting it together, jigging it up, making sure it's all 100% right and hit it with some thin CA. Could be wrong on this idea. Maybe Randy could suggest how to put the fuselage back together? This is a repair I haven't had to do...yet. But I don't let Larry The Cable Guy anywhere near my airplanes...

Steve

john ohnimus · « **Reply #16 on:** August 13, 2015, 08:03:09 PM »

Tonight's progress....

john ohnimus · « **Reply #17 on:** August 13, 2015, 08:05:11 PM »

More..

john ohnimus · « **Reply #18 on:** August 13, 2015, 08:13:02 PM »

Steve,

I work at a MRO. We do heavy aircraft maintenance for carriers all over the country/world. One of the last projects I worked on was a crown skin replacement on the B737 aircraft for Southwest Airlines. We reskinned 78 of them over 4.5 years. It was all about alignment... All of the skins in green we replaced...

Larry Fruits · « **Reply #19 on:** August 13, 2015, 10:29:35 PM »

John,
The patches on top the wing look great. Nice job. It should be real easy to blend the edges and have them disappear during final finishing. Well done.

Quote from: Randy Powell on August 12, 2015, 08:15:02 PM

I'm more worried about the tail than patching the wing. That damage looks nasty.

Randy, I agree about the fuselage tail repairs, but it appears John has some experience in getting or keeping things lined up. Although it may be on a bit larger scale than model planes.

With John's experience on the big birds, I don't think he is going to have any problems on this one. Patience and taking ones time is a must though.

To me, fixing the graphics is a whole different ballgame, unless just removing what's left and repainting it completely.

Larry

Randy Powell · « **Reply #20 on:** August 14, 2015, 11:49:04 AM »

Yep, looks like he knows what he's doing. On the tail, I would get it jigged up, zap it with some thin CA then sand the area and maybe put some .5 oz fiberglass over the effected area. Sand that down, fill and repaint.

It would probably be easier to just sand down the graphics and repaint. Trying to match what it there would be pretty tough. Finding the right font and then match the font point would be a tough go. If you sand it down you can find a font that is very close and then just repaint.

john ohnimus · « **Reply #21 on:** August 14, 2015, 12:08:06 PM »

Thanks Randy,

After some internal strife I think thats what I will do. I really wanted to keep as much of the finish intact as possible. Ken Grasser built the plane and is no longer with us, he was a great mentor and good friend for many years. So the graphics will be removed and reshot using the same colors at least. I have the color that he used (Sig Fokker Red) and surprising enough it seems to be in usable condition. I will try a test piece before I commit to shooting it onto the airframe. I again want to thank every one for the support and useful tips for this repair. Hopefully I will be able to fly it at Huntersville in October. I will be working tonight and tomorrow on setting the plane up for the repair on the tail, and I will take some pic's of the process and post them here.

Thanks to all,

Tony O

Tim Wescott · « **Reply #22 on:** August 14, 2015, 12:19:01 PM »

Quote from: john ohnimus on August 12, 2015, 10:11:11 PM

I have so me slow epoxy I plan on using, and a stragedy for reinforcing the structure.

It looks like you've already changed your mind on the epoxy -- if so, good. If not -- change it!

Epoxy would make a good strong repair, but it would be very nearly impossible to sand things out without leaving a ridge. The thin CA that Randy and Steve suggest will also leave a ridge, but it won't be nearly as bad. Personally, I think I'd consider using yellow carpenter's glue because it'll be marginally easier to sand than CA. But I'd have to be up close and personal with the break to be sure -- if I actually had it in my shop I may end up with the thin CA, too.

(From a sanding point of view Ambroid or similar glues are best -- but they dry so quickly there's absolutely no way that you could make a good repair to that tail using them. Go figure.)

john ohnimus · « **Reply #23 on:** August 14, 2015, 09:45:30 PM »

Tonight's pics.

Larry Fruits · « **Reply #24 on:** August 14, 2015, 10:26:40 PM »

Hi John.
Wow, if you have it lined up and it's straight, it looks like you have made a really nice repair to the fuselage. Looks good in the pic. Well done.

Larry

Randy Powell · « **Reply #25 on:** August 16, 2015, 02:36:53 PM »

Looks clean.

Brett Buck · « **Reply #26 on:** August 16, 2015, 02:49:12 PM »

Quote from: Steve Helmick on August 13, 2015, 04:59:01 PM

I think I would be fitting it together, jigging it up, making sure it's all 100% right and hit it with some thin CA. Could be wrong on this idea. Maybe Randy could suggest how to put the fuselage back together? This is a repair I haven't had to do...yet. But I don't let Larry The Cable Guy anywhere near my airplanes... Steve

That's certainly the way I would do it. We did the same thing for a very similar break in Bob Hunt's fuselage at the NATs a few years ago. Taking great care to not disturb the fibers, push it back together and it *should* go right back to the same alignment and the fibers will mesh nearly perfectly. Then take brand-new thin CA and drip it along the crack. Then go back with a pin, poke a hole every 1/4" or so along the crack, and put a drop in each hole. Then refinish.

Definitely glue it back together before attempting any sort of finish-stripping or other manipulation, because you don't want to take any chance of disturbing the fibers in the cracks. If you are really paranoid, you can then locally strip and sand down to bare wood, put on light fiberglass over the crack, and then refinish, but I don't think that is necessary.

Brett

john ohnimus · « **Reply #27 on:** August 16, 2015, 04:50:24 PM »

Brett,
That is exactly the method I have used here. I checked and rechecked the tail and there was a point when it was fully pushed together everything lined up. So far so good. It had a couple of packing tape repairs to the flap on one side and I fixed that up tonight. I am trying to get all of the repairs up to silver and then start "spotting in" the areas and build the finish back up. Hopefully without to much weight gain. I haven't weighed the plane so I guess I won't really know. It feels a bit heavy anyhow and I think I remember Ken eluding to the fact that it was heavy. Hopefully the piped O.S..40VF will pull it along.

Tony O

john ohnimus · « **Reply #28 on:** August 17, 2015, 10:53:50 AM »

So repairs are moving along pretty good so far. I plan on spending some more time on the tail area tonight, the only question on that area I have is that there are a couple of "divots" that will need to be filled. I tried some Elmers with balsa dust mixed in and it just kinda balled up, shrank and I have sanded it away as best I can. I made up a trial mixture of Sigment Aliphatic glue and some microballoons and it seems like a better filler. Any thoughts on this material? I am also a bit unsure as to whether or not to cover the areas on the tail that have been sanded down to bare wood. Just small patches with the edges frayed and then blended. Then build up the finish with silver. Once again I'm trying to not add too much weight. I am watching the pint of clear that I have slowly dwindle and I know that equals weight.

Thanks again for all of the great input!!!

Bill Johnson · « **Reply #29 on:** August 17, 2015, 01:06:14 PM »

My buddy, the Chief, uses Elmers interior wood filler. It sands easily at about 6-8 hours. I've used HobbyLite filler with good results. Light and sands like balsa.

Brett Buck · « **Reply #30 on:** August 17, 2015, 02:36:59 PM »

Quote from: Bill Johnson on August 17, 2015, 01:06:14 PM

My buddy, the Chief, uses Elmers interior wood filler. It sands easily at about 6-8 hours. I've used HobbyLite filler with good results. Light and sands like balsa.

You should be aware that some of these sorts of latex fillers are not compatible with butyrate dope, and can cause all sorts of problems (that's why "Model Magic" filler was renamed "Model Tragic").

Brett

Randy Powell · « **Reply #31 on:** August 17, 2015, 03:08:05 PM »

I'd use epoxy and microballons (maybe west systems 404 filler or similar). Or just use SuperFil. Best stuff I've ever used.

john ohnimus · « **Reply #32 on:** August 17, 2015, 08:59:38 PM »

Mixed up a test batch of the Sig Bond and micro balloons and it set up perfectly I even sanded the test piece to see how it acted. A little tougher than balsa but manageable. So it went into the "divots" I spoke of earlier and seems to be working fine. I just applied the silks span to the area and probably have put on the last coat of dope for the evening. I have a couple of areas to work tomorrow evening and I should be looking at spraying some silver this weekend. I will post some pics in a few.

john ohnimus · « **Reply #33 on:** August 18, 2015, 05:30:09 AM »

Last nights pics..... Having some trouble with the pics loading up.

john ohnimus · « **Reply #34 on:** August 18, 2015, 05:30:58 AM »

And one more !!!

john ohnimus · « **Reply #35 on:** August 18, 2015, 11:08:09 AM »

Just located the correct font!!!!

Dick Pacini · « **Reply #36 on:** August 18, 2015, 12:44:05 PM »

You might check with Aviojet (CFC Graphics) for the lettering. He can probably duplicate the entire graphics. He is very good at that and reasonably priced.

Avaiojet · « **Reply #37 on:** August 18, 2015, 01:28:55 PM »

Quote from: Dick Pacini on August 18, 2015, 12:44:05 PM

You might check with Aviojet (CFC Graphics) for the lettering. He can probably duplicate the entire graphics. He is very good at that and reasonably priced.

Dick,

I just saw this and that was nice of you. Really nice of you in fact. Thank you for that.

Yes, if John traces that graphic as close as he can, I could make one to cover it based on his tracing.

Not all programs type fonts identical.

Could just paint the entire wing and cover it all, but a tracing would still be needed to cover the "ghost."

John, send me a PM.

The model is looking nice.

Edited: Here, took a minute.

Bill Johnson · « **Reply #38 on:** August 18, 2015, 06:11:14 PM »

Quote from: Brett Buck on August 17, 2015, 02:36:59 PM

You should be aware that some of these sorts of latex fillers are not compatible with butyrate dope, and can cause all sorts of problems (that's why "Model Magic" filler was renamed "Model Tragic").

Brett

Thanks for the tip, Brett! I'll be sure and test any fillers I use.

john ohnimus · « **Reply #39 on:** August 18, 2015, 09:12:51 PM »

And more progress tonight. Also had some mods to the cowling to do. It's offset for a reason... I also wanted to show one of the pieces of tissue before I doped it on. Everything seems to be working out well.

john ohnimus · « **Reply #40 on:** August 18, 2015, 09:14:30 PM »

More pics

john ohnimus · « **Reply #41 on:** August 18, 2015, 09:15:25 PM »

Some more

john ohnimus · « **Reply #42 on:** August 18, 2015, 09:16:16 PM »

Gosh I wish I could post more than one...!

john ohnimus · « **Reply #43 on:** August 18, 2015, 09:17:05 PM »

john ohnimus · « **Reply #44 on:** August 18, 2015, 09:17:41 PM »

And lastly...

RC Storick · « **Reply #45 on:** August 18, 2015, 09:21:09 PM »

Quote from: john ohnimus on August 18, 2015, 09:16:16 PM

Gosh I wish I could post more than one...!

You can but you have to re size the pics

john ohnimus · « **Reply #46 on:** August 18, 2015, 09:25:55 PM »

Robert,

Trying to figure that one out. I am doing all of this from my iPhone and I cant seem to find where I can resize the pics. So far I am having to crop everyone before I post it or it won't load. Any ideas??

john ohnimus · « **Reply #47 on:** August 18, 2015, 09:27:43 PM »

By the way you are doing an awesome job with this site. I commend you. BTW you ever go to KY for a contest? Danville Ky say around 1991 or so??

RC Storick · « **Reply #48 on:** August 18, 2015, 09:36:38 PM »

Quote from: john ohnimus on August 18, 2015, 09:25:55 PM

Robert,

Trying to figure that one out. I am doing all of this from my iPhone and I cant seem to find where I can resize the pics. So far I am having to crop everyone before I post it or it won't load. Any ideas??

I have no idea how to do that on a I Phone. Sorry

Quote from: john ohnimus on August 18, 2015, 09:27:43 PM

By the way you are doing an awesome job with this site. I commend you. BTW you ever go to KY for a contest? Danville Ky say around 1991 or so??

Thanks. Yes I use to go there and Yes I knew Ken Grasser and I also knew that airplane

Jim Roselle · « **Reply #49 on:** August 18, 2015, 09:48:38 PM »

Quote from: john ohnimus on August 18, 2015, 09:25:55 PM

Robert,

Trying to figure that one out. I am doing all of this from my iPhone and I cant seem to find where I can resize the pics. So far I am having to crop everyone before I post it or it won't load. Any ideas??

Download an app called "picup", it's great.

Jim

Author Topic: Damage Repairs to the Paradigm (Read 8923 times)

Jim Roselle