Scale Soaring UK

I like the idea of magnets! just bought a bunch of rare earth jobbies off fleabay for about £4.

I like a solution with a bit of give too, so perhaps I'm contradicting myself.

The Let monoblock is the best solution I've ever used or seen, superb retention with that bit of give should you catch a crab. Fairly cheap too.

Ell

Eric,
Although a great shame that the wing movement resulted in damage to your model, it is probably worth noting that (at least in my opinion), using hard mounted electrical connectors on both sides of a mechanical interface without a rigid mechanical connection is 'an accident waiting to happen'.
I appreciate that this method provides a simple/automatic electrical connection as the wings are pushed home, but it generally also means that any vibration or other minor relative movement of the male/female contacts is likely to lead to intermittent contact, or as in your case, total loss of at least one electrical connection.

Unless you use connectors specifically designed for this type of use (D type connector for instance are not) then a much better arrangement is to hard mount only one side and leave the other side as a floating connector, thus avoiding the contacts taking any additional mechanical loads and also allowing the wings to move laterally to a degree.
I appreciate that this makes rigging a little more complex, but the connections MUST be reliable.
Any Reliability Engineer will tell you that two part connectors are a significant factor in equipment unreliability, even when used correctly.

Hey Ell,

I've been playing with magnets too, but the downside is that as separation increases, pulling force rapidly weakens. In contrast, with an elastic/spring system, pulling force increases with separation.

I also take on board Peter's well-made points about the risks of rigidly mounting both sides of electrical connectors. I've always enjoyed engineering these auto-connecting set-ups but will just mount one side from now for the reasons Peter discusses.

Ran up the Cub's motor for the first time this evening - wow it's exciting! The bummer is that I've got a major op tomorrow so will be laid low for a few months. How frustrating!

Rog

Good luck Rog (but I hope it doesn't come down to that!).

Peter,

Thanks for your comments on my posting. I did in fact put it online to highlight one incident that I had regarding the Multiplex wing retainers and maybe that it would be of assistance to others.

I only have two of my many models with the 'fixed-both-sides' arrangement, these being models that I have acquired second hand where to modify them to single fixed connector and floating wing lead would have been quite awkward to achieve and in my opinion, unnecessary.

The ASH26 has flown very successfully for over 15 years without incident and it was only my 'senior moment' that led to the heavy landing which resulted in very minor damage which has since been repaired and which cannot be seen. The other model is a Samba 'Kobra' dating from 1997 and which never has has connectivity issues as the wings are securely taped to the fuselage for each flight.

Regarding my other models which have socket and plug arrangements, these comprise three F3F type mouldies and three large scale models, namely a 5.2 metre 1/3rd scale Purbeck MDM-1 Fox, a 5 metre ASW 17, and a 7 metre H-Models ASH 25. All have 9 or 15 pin d-sub sockets mounted at the wing root moulding of the fuselage. The connections to the wing mounted servos are via floating leads which are secured to the socket, especially desirable and comforting in the case of the ASH 25, with 10 servos in the wings and a big financial investment.

Regards,

Eric

FrankS wrote:I use rubber bands and Multiplex wing locks (not on the same model ), but another option which was used on the Glenns Maule power plane was to have plastic bolts protrude from the wing secured to the fuselage by a captive nut screwed on with the flat face first (i.e. no fiddly screws and nuts to lose), this worked well and in a hard landing the plastic bolt would shear.

This is the best method I've used to date. It is very secure yet will shear in a hard landing. Also very convenient.
However retrospective fit isn't really possible as it would require a nut inserting behind the wing root in a suit table solid place, which can only be done during build.

MarkDev wrote:I am using springs from the local agricultural supplier (£11 for a mixed box) with success, also tried Rutgersson pins ('R' pegs) but no give in them, should have used some plastic washers or similar with them. Also used some thumbscrew fitting crimping down onto brass box over steel but again not much give in the system.

The Multiplex system is ok but seems to be a system for those with strong fingers, I have to use dry lube to get them together.

Should have used the same Spring that draws your wallet back to your pocket?

This system would be ideal for a Cub. A bit pricey, but it's only money! Watch the video to see how it works.
http://shop.rc-electronic.com/Wing-and- ... 265&p=5570

Hi

We discussed this issue a long tome ago and the consensus was that for wing connections there should be one fixed connection, for me normally in the wing, with the other side floating not fixed. The logic for this comes from aerotow situations when you may catch a tip which can result in the same issue as mentioned in the earlier post when a wing comes slightly apart.

Regards
Chris

Well, for now at least, I've gone for the low-tech (aka cheapskate!) solution - a couple of screws and a bent paper clip: