Control rod guide tubes in fuselage.

[Britpilot]

I've installed two 50mm long carbon fibre tubes where the elevator and rudder control rods pass through the fuselage. I glued them in with epoxy. It makes it look a lot neater and I think it may help keep the rods from bowing a little under compression loads in flight. I had to do this on my Art-Tech Spitfire as the elevator control rod would bow so badly under compression that it restricted up elevator movement.

[flydiver]

Nice reinforcement. I've seen the bowing problem on a number of planes, including a stock Cub. No idea why it started to suddenly do that.

[Britpilot]

The problem on my Spitfire was the relatively stiff elevator hinge. We have no way of finding out (without a wind tunnel) * but I expect the air load on the elevator is quite large when you apply full up elevator at high speed.

* I suppose you could hang your SC out of the window of your car at 30 mph and lift the elevator to find out but it might make the following drivers give you a wide berth!

[Crazy Horse]

Just wanted to say there is a far cheaper (costing nothing) solution. We all have these spray bottles of stuff in the house. When they are finished, remove the top spray section, then take off the clear plastic tube. It is an ideal size for the control rods. I epoxied mine in and as they are clear, you don't even notice them. The best four letter word in the English language...FREE. I hope these pics turn out OK, still a novice at doing this!

[Crazy Horse]

You might spot, (those of you with good eyesight) that there is a tell-tale sign of epoxy around the tail area. Well, I got this second hand and it needed a fix, so that and some cocktail sticks did the job. And yes, I did check the alignment to the main fuselage.

[spindeepster]

BRILLIANT!! Thank you for sharing.

[Crazy Horse]

spindeepster, Glad to be of help and give a little back to a great forum.

[spindeepster]

Just completed this mod....just looking for an open sky and minimal winds to test it out. I have also moved my control rods to the "tightest" settings on the control horns. This is gonna be good!!

[toff]

I know it's not really pertinent to this thread, but do remember that the spitfire was the first plane to go supersonic! Unfortunately, it was in a dive, and the shockwave would freeze the controls solid, resulting in a fatal crash, everytime. ( something the makers of the concorde studied endlessly!).
Your art tech spit is roughly 1/12th, and from what I've seen on youtube, in a dive this plane can hit maybe 50mph (or more!).
In scale thats 600mph!
Speed of sound is 761mph (ish), so, maybe (on a good day, with great height, no wind and a lot of nonsense on my part!), you are hitting the (scale) speed of sound, and thats whats causing the problem!
Hope your fix cures the bowing, and, if it does, always remember, 5 minute epoxy can beat the ( scale) sound barrier!

[iandhunt]

Highway to the DANGER ZONE!!!!!!

[Dillzio]

LOL, I'm not sure the 'scale speed of sound' actually creates the same shockwave as crossing the real sound barrier. For that to happen, the speed of sound would have to be scaled down as well, but since it's stays at about 330m/sec that's where the barrier is and stays. The shockwave is caused by catching up to your own sound vibrations, then they compound on top of each other and become powerful enough to shake a plane apart, that kind of effect can't really be 'scaled'.

I'd advise cubbers to be careful about anything they add that far back on their cubs because it can throw the CG off quite considerably and make it tail-heavy. I've just replaced my pushrods with 1.5mm CF and it works a treat, seems to be less bendy than the steel rods and they are dead straight. I just cut the ends off the stock pushrods and used CA glue and heatshrink to attach them onto the ends of the CF. About 5cm overlap seems to be ample for the joins.

[Crazy Horse]

Dillzio,
Thanks for your input, glad to have you back in the fold. You are obviously a very experienced flier and valued member of the beloved Super Cub Club. I believe that many members have missed your contributions. Congratulations on getting your Masters, it takes a lot of work, well done.

I like the idea of the 1.5mm push-rods, might do that myself, using the spare cf rod to do another mod that I have not yet seen on this forum as yet, pics and description on a later post, bear with me please.

However you say....I'd advise Cubbers to be careful about anything they add that far back on their cubs because it can throw the CG off quite considerably and make it tail-heavy. I've just replaced my push-rods with 1.5mm CF and it works a treat, seems to be less bendy than the steel rods and they are dead straight. I just cut the ends off the stock push-rods and used CA glue and heat-shrink to attach them onto the ends of the CF. About 5cm overlap seems to be ample for the joins.

So, you think that a tiny, thin 2" plastic tube, that does not even register on my very accurate scales as anything at all, will weigh more than the CA glue and heat-shrink that you have attached to the push-rods? As for a 5cm overlap, that is 2 inches in old money!

Sorry mate, but that just not equate with me, no offence intended. I sincerely hope that you get the flying bug again and post as prolifically as you did in the past, also that you get a job paying shed-loads for doing very little.

[Dillzio]

Thanks for the congrats craze horse

I don't think that adding a little bit of plastic tubing will add much weight, but remember, while I have added CA glue and heatshrink to my pushrods, I've also replaced a relatively large length of steel with CF so overall I'm still significantly lighter than I was.

My cub flies sooo much better now that i've got it balanced right, but I still need 1oz on the nose to make it balance out.

I might try replacing my home made oversized tail with a stockey and see if I can then remove my counterweight, and i'll see how it flies then. It's just a bit of a problem that the stock tail gets so easily damaged by nose overs - as it is at the moment you' couldn't ruffle my cub's feathers with a brick!

[iandhunt]

Gotta add what a gorgeous looking spitfire you have Britpilot!

[coupe1942]

I enjoy the ideas from this post and the exchange of ideas, even when disagreeing. It makes one think and the end result probably has more than just one solution to it. I thoroughly enjoy the idea that something is free and so useful, too. I make mods to my camera stuff all the time, but I learned when doing so, never tell a salesperson in a shop exactly what your looking for is really for. Many simply do not know anything except what is on a computer or on the desk directly in front of them. Old school guys don't rely on only the computer to know their stock and what may work or be adapted.

It took me several times in looking at the first few photos to clearly understand just what the mod was. Then, Bingo, the light bulb went on and I finally saw just what the mod was and where. DUH! This will have to be one of the first mods I make when my plane finally arrives in from HZ. Any of the different methods would be an easy fix. I am chronically looking at camera mounts to work with the least amount of weight to impact things. Threads like this remind me of the importance of always considering weight and location in factoring in any potential mods.