V tail mount repair help req

[Gonesoaring2003]

I need to replace the carbon tubes that hold my Skorp V tail on – have managed to remove the halves left in the fus (1 vaguely intact so I could measure it), but I'm not sure how to go about removing the halves left in the tails themselves. I'm thinking maybe drilling carefully with an undersized drill bit and hoping the tube will loosen or fall apart without damage to the tail itself, any body got any advice? I'll go and take a photo to post.  CheersAlex 

Edited October 27, 2011 by Gonesoaring2003

[Gonesoaring2003]

Or would do if Photobucket wasn't down!

[Gonesoaring2003]

Here we go: 

[Austin]

I think your suggestion to drill them out with an undersized bit would work fine.

[satinet]

if they are the original (insanely weak) hollow tubes, then you might be better off putting a longer bit of solid bit of carbon into the broken tube, then putting another bit of tube over the end of that.

[Gonesoaring2003]

Thanks for the replies.Tom - I did think about this but wasn't sure if inserting 4mm rod would be weaker than replacing the tube that has a 7mm outside diameter? 

[Bobbyr]

Glue something like a metal rod into the Tube ,           Put the metal rod into a vice , and pull and twist .   If it stays in ,  add the other piece over the top , if it pulls the tube out of the Tail job done,  and if it pulls whatever you glue into the rod out , Drill with a 5 mm drill .         I would be surprised if the tube was 7mm and not 6 . So with a 5mm drill you are not going to hurt the Tail .                         Good Luck                             Bob 

[Pete Burgess]

Alex, I had a similar problem with my HN Extreme, the carbon tubes on both sides of the V tail broke. (At first glance it looked as it the tube was in fact solid rod but in the event of damage it turned out not to be so.) I had to use drills, long nose pliers and files to remove all of the old, shattered carbon tube, fortunately carbon is a fairly soft material to work on in this manor. If your model has solid rod then drill it out. I bought some 7mm solid rod from Fibretech. It was then an easy job to glue in a new piece of rod. Having since flown the model all seens to be well

Edited October 27, 2011 by Pete Burgess

[satinet]

the hn extreme was made by the same bloke - I think eventually he was persuaded to use solid rods....

[satinet]

Gonesoaring2003 said:

Thanks for the replies.Tom - I did think about this but wasn't sure if inserting 4mm rod would be weaker than replacing the tube that has a 7mm outside diameter? 

I think it will be okay tbh. I installed carbon rods in my hn extreme, having had a skorpion, I knew it was a weak link. mr Fu fixed the tail on my skorp when it went wrong - the joiner was converted to a 4mm rod and with a fixed part in the tail (i.e cut off flush as suggested) and a sleeve in the fuselage. It has been raced and DSed (by Zim) since then - so I think it is fine.  If you hold the tail to the light the rod is actually the spar in the tail I think - don't think you can extract it as such. I guess it's a case of getting something that is a very snug fit - I don't know if mr Fu used a stock rod or laid up his own from carbon - I think on the extreme a 4mm rod was a bit loose. Anyway, like I say hold the tail up to the light - i think it will show that the rod is the spar in the tail - it certainly was on my extreme - although I couldn't tell on my skorp as it was a black tail.

[Gonesoaring2003]

Thanks Tom Will have a look tomorrow 

[Pete Burgess]

Tom, interesting about your comment on your Extreme tail. On mine the V tails have spars of carbon fibre tows with a balsa shear web/spacer, the carbon rod inserts into the tail by about 2 1/2 inches.Of course the Skorp may well be different. 

[satinet]

Pete Burgess said:

Tom, interesting about your comment on your Extreme tail. On mine the V tails have spars of carbon fibre tows with a balsa shear web/spacer, the carbon rod inserts into the tail by about 2 1/2 inches.Of course the Skorp may well be different. 

That might be the case Pete. I seem to remember it being a continuous piece of carbon, but I don't have the model anymore so I couldn't say. Certainly the one I had which was one of the first in the country had the same thin walled carbon tubes as the skorpion with the piece of wood dowel inside (not glued in).  I extracted the dowel and glued in a solid  carbon rod. 

[Gonesoaring2003]

Right, had a look at the tails this afternoon and it definitely looks more like what Pete describes a spar with carbon caps top and bottom, so.............. I was feeling brave, got the drill set out and carefully drilled out the old carbon tube increasing 1/2mm each time til I eventually got to 7mm, it would seem the tube only extended about an inch into the tail. Anyway i now have 7mm holes which my new 7mm tube fits tightly into - 2 questions - should I use the 7mm tube I've got which is definitely thicker walled than the original or should i buy some 7mm rod? Is it necessary to fix the tube/rod into the tails or could I leave them floating in case I break one in the future? (i realise i need to stop them moving through and  out the bottom of the fuz)  CheersAlex 

[Gonesoaring2003]

Sorry one more question. How is it best to cut carbon tube/rod? I was thinking wrap with masking tape and then gently with a junior hacksaw - would a razor saw be better or even a dremel? 

[Yoyo]

Gonesoaring2003 said:

Sorry one more question. How is it best to cut carbon tube/rod? I was thinking wrap with masking tape and then gently with a junior hacksaw - would a razor saw be better or even a dremel? 

Not certain myself but I'd use a razor saw. I think a dremel might get it too hot. The really important thing is to avoid splinters and definitely avoid breathing any cutting/sanding dust. It's dangerous.

[Phil.Taylor]

Gonesoaring2003 said:

2 questions – should I use the 7mm tube I've got which is definitely thicker walled than the original or should i buy some 7mm rod? Is it necessary to fix the tube/rod into the tails or could I leave them floating in case I break one in the future? (i realise i need to stop them moving through and  out the bottom of the fuz)  CheersAlex 

Definitely rod – not tube – or you will only have to do this malarkey all over again…much strongercutting it (rod) I just use a small hacksaw – bit at a time, going all round it, before cutting through the centreand yes "floating" (but firm) - same reason - just in case...Phil. Edited October 28, 2011 by Phil.Taylor

[Woodstock]

Gonesoaring2003 said:

Sorry one more question. How is it best to cut carbon tube/rod? I was thinking wrap with masking tape and then gently with a junior hacksaw - would a razor saw be better or even a dremel? 

The razor saws I know and use are timber saws only with pretty fine teeth: carbon will ruin a blade in a few seconds. The Dremel cutting discs work well.  Tape as you say.  The steel disc with what appers to be diamond coating works best, as it's thinner and tougher than the fibre cutting disc. Otherwise, use a hacksaw.  Be prepared for rapid wear on the blades too, but at least they're cheap.