Cotter pins and R clips as a retention system

[Shane Sunday]

Hello Folks. I was hopeing I could get some opinions on a rigging system for a Bipe. I'm forever losing tiny bolts at the field and fumbling with ungainly tools to screw on and rig my PT17 steerman. This promted me to looking at faster ways of rigging. I was wondering what your thoughts would be to the cotter pin and R clip idea. As I can see it the forces on the wing are in the vertical up and down sort of plain not so much on the back to front of the machine. My idea was to attach the cotter or SPLIT pin to the strut, the head of which would then go through the mount on the wing. It would have to be very tight fit. once the cotter pin is through the hole on the wing mount you then slide the R clip from the LE face to complete the join.

Now I've tried this and it is very difficult to get that R clip back off. Saying that, I'm aprehensive about commiting the model to the sky's without further advice.

What are your thoughts?

[Colin Carpenter]

Shane. Have a look at the Ripmax  Wots Wot ARTF thread. I use R clips and they have proved faultless. Colin

Edited By Colin Carpenter on 15/04/2016 10:39:38

[john stones 1 - Moderator]

Sounds o.k to me Shane, there's some good little clips/pins sold for r/c cars that fit the purpose, nuts n bolt are a pain as you said

John

[Geoff S]

Do you mean the interplane struts?

I have a Great Planes Super Stearman with a Mackay 30cc petrol engine, which may be a similar kit to yours (they did both). I also got fed up with fixing 8 bolts to hold the IP struts, particularly as all the threaded components are those strange US only imperial threaded ones I've grown to hate. My first step was to fit 4mm bolts at each fixing point, permanently attached, which meant all I had to do was fit the nuts. As I have a stock of metric nuts it wasn't the end of the world if I lost one. But it was still a pain. I ended up replacing the nuts with normal fuel tube, which is a tight fit on a 4mm bolt and the thread stops the tube from sliding off easily. That's much quicker and seems to work perfectly well.

Having said that, DBs idea I use on my 58" Tiggie is even better - hooks into eyes at the bottom and a 14g bike spoke pushed through eyes and held with an elastic band at the top. The eyes are simply modified split cotters. Look on DB S & S web site for details.

Geoff

[bert baker]

I like the way my DB SE5A is done.

It has a split pins mounted in the wings with the round head protruding.

On the bottom of the strut it has an L shaped piece of wire that also has a small bracket with a hole through for the flying - landing wires to conect to with a standard clevis.

No tools or nuts and bolts required .

The L shaped wire goes through the split pin head and the flying wires keep it pulled against the split pin head.

The L shaped wie does need to be long enough so any slack in the Flying wires does not allow the L shaped wire to slip out of the split pin head.

Edited By bert baker on 15/04/2016 11:02:59

[Martyn K]

I use these (home made collets with R clips from RC Cars) on my Precedent T240 for the wing struts. It works well and is a lot less of a palaver than nuts and bolts. I haven't lost one yet

Yet...

 

Martyn

Edited By Martyn K on 15/04/2016 10:55:46

[Shane Sunday]

You guys are great! Thank you very much. WHile I'm at work at the moment I cannot take a photo of my setup. The R clips I have are very small so as not to be overly visible. Difficult enough to bend though. I feel a thousand times better about putting this bird back in the air. Colin your setup looks great. The boys at the field may be bricking it when I start though.

Thanks again lads.

[bouncebounce crunch]

R clips would be best.

[bert baker]

[bert baker]

[GONZO]

https://en.wikipedia.org/wiki/Cotter_(pin)I see we've adopted the American definition of cotter pin instead of the UK one.

Edited By GONZO on 15/04/2016 11:51:03

[bert baker]

What is the wingspan of the model

[Geoff S]

Posted by bert baker on 15/04/2016 11:18:36:

I don't have either flying or landing braces on my 58" Tiger Moth but the system is similar to this. In my case I made the hooks go through 180 degrees so the can't come out as long as the top is restrained. The need almost to lie on the wing before they'll unhook.

Geoff

[Andy48]

Cotter pins and R clips hold the blades on my rotovator. Can't imagine a model would be under anywhere like as much stress.

[Kevin Wilson]

Strange how I read all the posts and visualised a split pin wherever 'cotter' was referenced. Totally subconsciously.

However if you had asked me to draw a cotter pin it would have been the circular wedge pin used to secure bicycle cranks.

(and this site spell check facility wanted to put a Z in visualised, thats a zee in case you were confused)

[GONZO]

Well being in my late 60's I visualised the opposite. When ever I see cotter pin I see in my mind the bicycle crank securing bolt. Therefore this thread didn't make sense at first. Must be a generational thing.

[Darrell Woodward]

Mick Reeves Models does some really nice rigging bits: **LINK**

 

Edited By D. Woodward on 15/04/2016 16:30:28

[Geoff S]

Here's the method I use successfully on my Stearman for holding the interplane struts. The fuel tube holds the struts very firmly and even without it the struts are quite difficult to remove so the chances of any problems in flight are minimal. The bolts are held permanently on the wing at the top and the strut at the bottom.

Geoff

[J D 8]

Cotter pins,lynch pins,and R clips are commonly used in agriculture to retain large bits of machinery.

[Geoff S]

Posted by john davies 8 on 17/04/2016 22:42:42:

Cotter pins,lynch pins,and R clips are commonly used in agriculture to retain large bits of machinery.

So? A model aeroplane isn't a large bit of machinery. After all I use elastic bands to secure the wings on my Limbo Dancer but I wouldn't dream of using them to hold the bucket on a JCB.

Geoff

[Former Member]

[This posting has been removed]

[Frank Skilbeck]

Just built a Keith Humber Towrag biplane and the struts are attached with a "90deg" Z bend at the top, i.e. thread in turn strut through 90 degrees and then a two horizontal sections at the bottom, one on strut and one on wing secured with some fuel tubing. Very simple quick and effective, I'll be using this more in the future.

Also friend 4.5m Harbinger glider wing struts are held in place with pins retained with R clips, just don't lose them.

[Tim Mackey]

I made up some little flat headed dural locating pins on my little lathe to ease the fitting of the wing struts on my Grunau baby. The pin passes through a tab fixed permanently to the bottom of the strut, and a small "U" bracket fixed to the fus. Crucially, I fitted a short piece of fishing line to the "R" clips which pass through a hole drilled into the end of the pin. This way the clips are never lost in the grass, and never forgotten when leaving home

[Former Member]

[This posting has been removed]

[J D 8]

Posted by Geoff Sleath on 17/04/2016 22:45:30:

Posted by john davies 8 on 17/04/2016 22:42:42:

Cotter pins,lynch pins,and R clips are commonly used in agriculture to retain large bits of machinery.

So? A model aeroplane isn't a large bit of machinery. After all I use elastic bands to secure the wings on my Limbo Dancer but I wouldn't dream of using them to hold the bucket on a JCB.

Geoff

You would need a very large elastic band to hold the JCB bucket on,would probably work just not practical.Cotter pins,R clips ect come in a wide variety sizes and are a practical way of retaining items that need a quick release system. John.