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Cotter pins and R clips as a retention system

thinking of a fast way to rig a bipe need opinions.

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Shane Sunday15/04/2016 10:28:39
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342 forum posts
160 photos

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 Carpenter15/04/2016 10:37:38
594 forum posts
35 photos

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 115/04/2016 10:41:43
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10793 forum posts
1481 photos

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 wink

John

G194015/04/2016 10:44:19
3523 forum posts
1 photos

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 baker15/04/2016 10:54:51
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1502 forum posts
306 photos

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 K15/04/2016 10:55:12
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5033 forum posts
3677 photos

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 Sunday15/04/2016 10:56:52
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342 forum posts
160 photos

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 crunch15/04/2016 10:57:10
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1739 forum posts
212 photos

R clips would be best.

bert baker15/04/2016 11:03:34
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1502 forum posts
306 photos

wing strut drawing.jpg

bert baker15/04/2016 11:18:36
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1502 forum posts
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wing strut drawing.jpg

GONZO15/04/2016 11:23:23
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1334 forum posts
14 photos

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 baker15/04/2016 11:25:12
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1502 forum posts
306 photos

What is the wingspan of the model

G194015/04/2016 12:29:16
3523 forum posts
1 photos
Posted by bert baker on 15/04/2016 11:18:36:

wing strut drawing.jpg

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

Andy4815/04/2016 12:51:45
1409 forum posts
5 photos

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 Wilson15/04/2016 14:17:47
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386 forum posts
13 photos

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)

GONZO15/04/2016 15:15:26
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1334 forum posts
14 photos

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 Woodward15/04/2016 16:28:32
94 forum posts
1 photos

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

 

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

G194017/04/2016 21:58:19
3523 forum posts
1 photos

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.

stearman 170416_2.jpg

Geoff

J D 817/04/2016 22:42:42
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1340 forum posts
78 photos

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

G194017/04/2016 22:45:30
3523 forum posts
1 photos
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

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