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January 16, 2019, 00:04:39 AM

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Author Topic: Wot4 Foam-e Mk2 wing fixing  (Read 371 times)

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Offline PDR

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Wot4 Foam-e Mk2 wing fixing
« on: September 23, 2018, 09:44:39 AM »
I have one of these which I tipped out of the box (I can't say I "built" it) a year or so back. I haven't flown it, of anything else, at all this year due to other commitments - mainly the fact that I spend 4 days a week north of the Wall helping the Wildlings develop Lancashire's anti-white-dragon defence systems*.  So it has been sitting ready for use on the bench in the workshop since before Xmas.

Anyway, yesterday I cleared the bench because I've got the bug to start some building again (more anon), so I picked up the Wot-e and noticed that the wing seemed to "rock" as if the bolt was loose. I gave the TE a gentle one-finger tug to test this theory and the wing just came off - the wing bolt pulled right through the wing, which I thought showed a distinct lack of gratitude and a general refusal to be a team player...

For those not familiar with the model - the wing is made up of a number of EPO  mouldings bonded together, with some moulded plastic (look like ABS or HIPS - certainly not nylon) fittings for the LE location dowels and the rear bolt location. The rear bolt location moulding is essentially a flat plate to spread the load, with a tube leading down to the bolt seating face so that the (metal) bolt head is well below the surface of the wing. The bottom of this tube with the bolt-seating face has completely detached, so nothing is holding the wing on at all. My theory (FWIW) is that having been in the workshop with the wing bolted on it since it last flew on a frosty day last October it has been through temperature cycles from about -6degC to +35degC, and the expansion of the foam of the wing has overstressed the part. Fortunately this isn't hard for me to fix - I can turn-up a flanged collar in either dural or stainless that will just drop in. I'm just glad I spotted it before I took it flying again!

But it has made me think more about the storage conditions for my models - especially the consequences of temperature cycling. I've fallen into the habit of leaving wings bolted on until I actually need the space, but I think from now on I'll make a point of loosening metal wing bolts in foamies. It's no great hassle to back the bolts off a couple of turns and then re-tighten them on arrival at the field.

Anyone else suffered a similar failure?

PDR

* my Better Third suggested my job title should be changed to "Head of Marriott Points Acquisition" as I've spend 3 nights a week in the place for over 15 months (~246,000 points this week and counting). I just wish they gave air miles on the company jet...
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Offline itsme

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Re: Wot4 Foam-e Mk2 wing fixing
« Reply #1 on: September 23, 2018, 10:04:59 AM »
Although excellent at what their job is- shake the box and go flying- these wot thingies are not long lasting. If you spend time on a few mods, however, they can give good service for years. Battery cover- I line the edges with mirror ply. Extra glue to the motor fixings. better wing bolt fixings (as above) and coat all delicate edges in cyano to harden them. I have just spray painted an Acrowot foam-e as I detest the stick on decals but its not easy as masking tape of any kind picks off the paint. I bought some De Luxe Materials Foam Armour at the Nats. Advice- dont bother. May be epoxy will harden the foam, but this stuff wont even stay on it.

Offline Michael_Rolls

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Re: Wot4 Foam-e Mk2 wing fixing
« Reply #2 on: September 23, 2018, 11:12:08 AM »
What has surprised me is that I had an E-wottie a few years back which did a lot of work until the elevator servo failed in flight (after about 5 minutes and yes, everything worked OK on the ground) so  I bought another one last year. With Veronica's illness and death I didn't get round to flying it until this April - and it is WAY tail heavy - I was quite proud of myself for getting the thing down in one piece (until the breeze caught it and a semi-cartwheel tore the wing loose). Haven't got round to doing anything about it yet - motivation at the moment is very low - haven't actually gone flying since that day. However, can't understand how, when the first one flew perfectly out of the box, number two - with identical radio gear and battery size, weight and location - could be so way out of trim. Checking after the event, I would have thought the CG was reasonably located  - but it didn't seem it whilst in flight. Trouble is, I never made a note of the CG position on number one, so have no idea how they compare.
Mike
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Offline itsme

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Re: Wot4 Foam-e Mk2 wing fixing
« Reply #3 on: September 23, 2018, 15:16:19 PM »
What has surprised me is that I had an E-wottie a few years back which did a lot of work until the elevator servo failed in flight (after about 5 minutes and yes, everything worked OK on the ground) so  I bought another one last year. With Veronica's illness and death I didn't get round to flying it until this April - and it is WAY tail heavy - I was quite proud of myself for getting the thing down in one piece (until the breeze caught it and a semi-cartwheel tore the wing loose). Haven't got round to doing anything about it yet - motivation at the moment is very low - haven't actually gone flying since that day. However, can't understand how, when the first one flew perfectly out of the box, number two - with identical radio gear and battery size, weight and location - could be so way out of trim. Checking after the event, I would have thought the CG was reasonably located  - but it didn't seem it whilst in flight. Trouble is, I never made a note of the CG position on number one, so have no idea how they compare.
Mike
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Offline Michael_Rolls

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Re: Wot4 Foam-e Mk2 wing fixing
« Reply #4 on: September 24, 2018, 07:37:45 AM »
Usually they are spot on..




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That's normally been my experience as well - haven't felt like following through, but perhaps one day the enthusiasm will return.
I did have one entertaining kit about 20 years or so ago (can't remember for sure which it was so I won't risk maligning anyone in error). A tail dragger, the CG according to the instructions would have been quite a bit on front of the point at which the wheels touched the ground, IIRC 95mm had mistakenly been printed as 65mm
Mike
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