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Carbon rod / tube?


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Another caution:
​Even pushing a steel wire into a carbon tube can split it as they fibres on small tubes are generally parallel along the length. Any expanding force is only as strong as the resin so threads are generally a no - no too.
​Only a spiral wound tube has strength in many directions.
​You can guess how I know!

Levanter

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Posted by Levanter on 25/03/2018 19:15:46:

Another caution:
​Even pushing a steel wire into a carbon tube can split it as they fibres on small tubes are generally parallel along the length. Any expanding force is only as strong as the resin so threads are generally a no - no too.
​Only a spiral wound tube has strength in many directions.
​You can guess how I know!

Levanter

 

After cutting the carbon tube to length, wind some kevlar thread around the last 1/2" or so at each end. Secure the thread with cyano.

Edited By PatMc on 25/03/2018 19:46:48

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I don't think I'd fancy using balsa. Spruce perhaps or Ramin dowel but not balsa.

I bought some 5mm carbon tube with some very neat end fittings from LMA show at Gaydon last Autumn. It wasn't staggeringly expensive and even over about 200mm unsupported in my Mew Gull very stiff and positive with no flex. The annoying thing I can't remember who the trader was and, as I paid in cash and discarded the receipt (if there was one!) I have no means of finding out. His stall was opposite the SLEC stand.

Geoff

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Posted by eflightray on 25/03/2018 20:23:58:

What's wrong with using a balsa stick with a short wire rod attached at each end ?, it's been used for years.

Modern materials are not always needed just because they are there wink

Ray.

err.......because in all probability it would snap at the worst possible moment?, the then out of control model potentially hitting somebody or something? Its dangerous? Things have moved on. But many thanks for the post.

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Posted by SIMON CRAGG on 25/03/2018 23:37:01:
Posted by eflightray on 25/03/2018 20:23:58:

What's wrong with using a balsa stick with a short wire rod attached at each end ?, it's been used for years.

Modern materials are not always needed just because they are there wink

 

Ray.

err.......because in all probability it would snap at the worst possible moment?, the then out of control model potentially hitting somebody or something? Its dangerous? Things have moved on. But many thanks for the post.

1/4" square hard balsa push-rods was used for years, probably since the introduction of RC, and probably still is used by many. It was used in most aerobatic models including the 60/61 size engines, 60" span etc.

It.s advantage was it was light compared to hard wood dowel.

The only time I remember one breaking was in a fairly major crash where the fuselage broke as well. Heavy push-rods would often strip a servo gear in a crash owing to the momentum.

Don't write things off because they seem old fashioned, there was often a good reason why we did things that way in the past, (and still in the present).

I assume many here have never built a fuselage using 1/4" square balsa wink

 

Ray.

 

Edited By eflightray on 26/03/2018 14:32:09

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Posted by eflightray on 26/03/2018 14:31:28:
Posted by SIMON CRAGG on 25/03/2018 23:37:01:
Posted by eflightray on 25/03/2018 20:23:58:

What's wrong with using a balsa stick with a short wire rod attached at each end ?, it's been used for years.

Modern materials are not always needed just because they are there wink

Ray.

err.......because in all probability it would snap at the worst possible moment?, the then out of control model potentially hitting somebody or something? Its dangerous? Things have moved on. But many thanks for the post.

1/4" square hard balsa push-rods was used for years, probably since the introduction of RC, and probably still is used by many. It was used in most aerobatic models including the 60/61 size engines, 60" span etc.

It.s advantage was it was light compared to hard wood dowel.

The only time I remember one breaking was in a fairly major crash where the fuselage broke as well. Heavy push-rods would often strip a servo gear in a crash owing to the momentum.

Don't write things off because they seem old fashioned, there was often a good reason why we did things that way in the past, (and still in the present).

I assume many here have never built a fuselage using 1/4" square balsa wink

Ray.

Edited By eflightray on 26/03/2018 14:32:09

We have used 1/4" square on many vintage models over the years, and even competed at county level so we know the pros and cons. Having not purchased carbon rod for many tears, we were just inquiring as to where the best deals are to be had at the moment. For info. the carbon is required for a 200kph EDF Hawk, so hence the reason for something more substancial.

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