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SBach 300 - Repairs and modifications

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Ron Gray01/04/2020 07:36:23
2521 forum posts
1009 photos

You are correct in one respect Gary, I have used a naca duct shape but it is upside down and the wrong way round! But, like I said, this is guesswork hence why it is a removable piece.

Thanks Peter.

Ron Gray02/04/2020 15:31:34
2521 forum posts
1009 photos

No too sure if anyone wants to see more of this re-construct or have I bored the pants off you already? Not a problem if I have!!!! (well, let's face it. if I have then it's too late anyway cheeky)

john stones 1 Moderator02/04/2020 16:00:02
11923 forum posts
1531 photos

Carry on, we can always learn from others, recently repaired a Slick wing/aileron for a mate, it's interesting once you get under the covering. wink

Ron Gray02/04/2020 17:10:22
2521 forum posts
1009 photos

Well one thumbs up is enough for me John, so I'll continue.

On first inspection the damage to the tail wasn't too bad, a crack in one half was my initial thought. However, when I looked at it again I saw that one half was not only damaged but was also bent back from the fuse. No problem, the tail is in 2 halves so simply unbolt it and remove to fix. Uh, no, the previous owner had glued the alloy wing spar tube into the carbon tubes so a simple slide off was out of the question. After careful (well not so careful) brute force I was able to break the tube free, trouble was it was the the carbon tube that broke free and it was the other tail half it broke free from!



The wing tube pulled out from the wrong half


At least I was now able to bend the alloy tube straight so that the broken half sat parallel to the fuse, but in doing so the dowel locator pegs had to be cut off. This meant that I then had to somehow fit new ones but I couldn't get the tailplane off to drill out the old one! Using a small drill bit at an angle I managed to remove enough of the dowel.


But how to fit a new dowel if I can't pull the tail away from the fuse? answer was to make a long dowel that went right through the fuse and would also serve for the other tail half.



Having spent far too long on this part I decided to rest my brain and tidy up a couple of things inside the fuse. Firstly I had to raise the rudder servo due to the new can tunnel.


And the last (hopefully) fuse job was to re-attach the RX mounting tray (mustn't forget the second RX which is in another 'plane!).


Now back to the tail. The covering was stripped back and the repairs made.


Then recovered


So that completes the fuse re-build.

Next up, the wings and I was not looking forward to this part as my memory told me that one was in a bit of a state!

Funny how memory can play tricks with you, damage was nowhere near as bad as I remembered and considering the state of the fuse it really is quite amazing. However, I tell myself that it must have been good flying to have landed it level in the middle of that ploughed field!

One wing, looks like a spat puncture


Other wing, goodness knows what caused this


Repairs to these areas tonight.

Edited By Ron Gray on 02/04/2020 17:11:09

john stones 1 Moderator02/04/2020 17:34:52
11923 forum posts
1531 photos

Looking good Ron, a bonus there's no fancy film job to redo ? A model I've always wanted.

Ron Gray03/04/2020 15:36:32
2521 forum posts
1009 photos

On with the repairs, and you will be pleased to know that this is the last post in the series, coz it's finished with only flying left to be done, at some point!

Cutting back the film revealed the full extent of the damage, still nowhere near as bad as I thought it would be.



And repairs done






Covering applied




The finished article





I may spend a bit of time remodelling the cowl as it has been cut out for different engine so there are quite a few redundant holes / cut outs. But the main job is done and can't wait to get it back in the air with its new engine (probably will run the engine up in the garden next week when the new CDI unit arrives from Morris Mini Motors.

So what's the next job? Hmm, recovering the SIG Rascal is on the list but that's quite a daunting task as it's the 110" one!

Edited By Ron Gray on 03/04/2020 15:37:07

Adrian Smith 103/04/2020 16:22:08
2493 forum posts
1276 photos

Nice repair there, Ron.

You have inspired me to do a refurb job on my Weston Capiche 140. It looks a bit sorry for itself in the corner and while it is essentially undamaged, it looks a bit tatty and shall we say well used! A fair bit of replacement recovering will be required and a few bits of airframe replaced, but the frame and wings are sound. I have everything in stock to effect repairs. I even have some spare servos. It used to house an OS 160 FX (long gone) if I recall, but I will be relaunching it as an electric project. I will start a new thread soon with some photos of progress as I fear we are going to be workshop confined for some while yet. sad

Gary Manuel03/04/2020 16:40:13
2471 forum posts
1564 photos

Nice work Ron.

I've got a similar set of repairs to do after I ran out of skill (and luck) with my World Models Ultimate Biplane. I've been putting off the repairs for a while now, but you've inspired me to get on with it.

Edited By Gary Manuel on 03/04/2020 16:41:06

Bob Cotsford03/04/2020 16:47:45
8945 forum posts
498 photos

That's very neat Ron, and yes, you were lucky with the wings. I'm reluctant to do extensive repairs these days, if I damage a model badly I see it as an excuse for a new airframe face 1. Oddly I do take on airframes abandoned by others and make them airworthy again. I then take them up the field and attempt to make them un-airworthy again!

cymaz03/04/2020 16:56:59
9597 forum posts
1267 photos

Excellent workyes, enjoyed the read

john stones 1 Moderator03/04/2020 17:30:00
11923 forum posts
1531 photos
Posted by Bob Cotsford on 03/04/2020 16:47:45:

That's very neat Ron, and yes, you were lucky with the wings. I'm reluctant to do extensive repairs these days, if I damage a model badly I see it as an excuse for a new airframe face 1. Oddly I do take on airframes abandoned by others and make them airworthy again. I then take them up the field and attempt to make them un-airworthy again!

face 1

john stones 1 Moderator03/04/2020 17:32:01
11923 forum posts
1531 photos

As Eric said to Ernie "You can't see the join" nice job Ron. yes

Ron Gray03/04/2020 17:41:36
2521 forum posts
1009 photos

As the spats got trashed in the crash I may well print off a new pair for the Sbach, when I've finished printing face masks for the NHS!

john stones 1 Moderator03/04/2020 18:01:17
11923 forum posts
1531 photos

Not a great fan of spats myself, I like these ones though on my Sukhoi, go faster spats. wink sukhoi 001.jpg

Ron Gray03/04/2020 18:21:15
2521 forum posts
1009 photos

Normally I would agree John but as we fly off tarmac (or in the case of the Sbach, ploughed fields) spats don't usually cause an issue and they certainly make the 'plane look better. But I've lots of other things to get on with before I get round to them!

Peter Jenkins03/04/2020 20:36:34
1725 forum posts
314 photos

Excellent job Ron. Fingers crossed for an uneventful life for the Sbach once the lockdown ends.

Ron Gray03/04/2020 22:26:15
2521 forum posts
1009 photos

Thanks guys for your nice comments! Looking back at the completed shots, it really does need a pilot in there, so maybe I'll sneak a print in before the next batch of face masks.

@Peter, looking forward to getting it in the air but based on my experience with the previous one (your old one) I may invest in a carbon wing tube instead of the alloy one!

Peter Jenkins04/04/2020 23:53:08
1725 forum posts
314 photos

A carbon tube will certainly be lighter Ron but remember these light weight aerobatic jobs don't like having power on when heading downwards. Build up too much speed and then a quick yank bends the tube! Keep the speed and elevator movement in check and the alloy tube will be fine unless you want to lose a bit of weight.

SR 7105/04/2020 01:23:47
466 forum posts
140 photos

Hi Ron the canister that you have used will it make any difference to the noise level of the DLE

Nice repair job, i like doing repairs/refurbishment, with my flying i et a lot of practice frown

Ron Gray05/04/2020 07:19:49
2521 forum posts
1009 photos

@Peter - it was more to prevent a permanent bend. If you recall, my previous Sbach returned home after a spirited time in the air (no power on down lines!!!) displaying a large amount of dihedral, which it didn’t have on take off.

@SR - my experience of all of my DLEs is that a can makes a marked difference to the noise levels, hence why I went to the pains of fitting one to this model even though it wasn’t designed to have one fitted. IMO JMB or Zimmerman ones are the best.

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