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Geoff's Wot4 Mk2 electrification

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Biggles' Elder Brother - Moderator13/10/2018 20:13:03
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Oh agreed Ron, each person is on their own voyage of discovery and will find their own solutions.

Mine would spin "as built" but the spin was difficult to enter, slow and frankly unconvincing with a tendancy for it to open up into a spiral dive rather than remain a true spin about the CoG. But for me moving the CoG back cured that as well (as you might expect) and the model now spins fine.

There is always more than one way to skin a cat in this hobby, that's one of the things that makes it so interestingisn't it. Two solutions, both work.

BEB

Geoff Sleath13/10/2018 21:33:01
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Posted by Devcon1 on 13/10/2018 18:17:32:

Hi Geoff,

Watching with interest, to remove film to a line I've tended to, as you say, use a soldering iron lightly drawn over your cut line.

A couple of questions, what servo are you going to use for elevator and I'd be really interested in seeing a picture of how the two wing halves are joined as I'm struggling to visualise the method.

How is the weight going ?

Thanks

Devcon1

I'm going to try the soldering iron method. I'll do a practice run further down the fin where it won't matter as it'll be well below the joint line.

I'm using K Power MO 200 mini-servos throughout. They have the same torque as a Futaba 148 (3kg cm) but have dual ball bearings and metal gears and are about 2/3 the weight. I bought them from Airtek a while back (I don't think they sell them now). They weren't super cheap - about £7 each but £25 if you bought 4 off IIRC.

The wing assembly is quite straight forward and it's easy to do a trial dry fit just to get used to the method. Just push in the dihedral brace into one wing (use the one with the short plastic anti-twist insert - the starboard one in my kit) then simply push the wings together. There's no dihedral; the wing is flat.

As I write, I'm waiting for my dihedral brace to cure in the stbd wing. I used 5 minute epoxy for that. Once I'm satisfied it's cured I'll mix some 60 minute epoxy (I like time to make the joint without feeling rushed) then just push the wings together. I'll clamp the 'wing dowel' which is actually a tab on each root rib at the L/E and clamp the T/E using the aileron recesses with some miniature sash cramps I have. As the instructions say, it's as well to mask off the roots of each wing to keep surplus adhesive off the pretty parts. I'll leave my wing until tomorrow. There's no rush as our club's (Ashbourne) scale day has been postponed until next Sunday

If it all goes well in the next hour I'll take a picture.

As I mentioned earlier, I did a loose assembly and it weighed 4.26 lbs. I anticipate the final all-up ready to take-off weight to be around 5lbs.

Geoff

Geoff Sleath13/10/2018 22:10:08
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Here's the wing joining. Just clamped at the leading and trailing edges. 60 minute epoxy with masking tape to keep it off the film.

dscn2165.jpg

There's not a lot more you can do to clamp the 2 wings together but I think it will be enough.

Geoff

Devcon113/10/2018 22:18:09
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I understand now.Thats a very neat way of doing it. Thanks....
Ron Gray13/10/2018 23:26:38
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@Geoff - that's exactly how I clamped mine together, worked a treat!

@BEB - I've got tail weight too!

f92a09b2-26db-437b-93d7-0606747249e3.jpeg

Bruce Collinson15/10/2018 10:14:49
393 forum posts

Geoff,

Beware of using a butane soldering iron on your film cut line, as mine spills heat out of the side and leaves scorch marks (I attribute them to 6s LiPos if anyone asks). I found a 20W iron with a fine tip and a steel ruler very effective although there's still a slightly crinkly edge which needs ironing back down.

BTC

RC Plane Flyer15/10/2018 10:58:59
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Hi Ron. On your elevator set up in picture above is that the inner snake I see joining the metal rod to the clevis ? I had a set up like that but found the snake flexed on a up elevator option. An old timer advised me to always get the metal rod to join to the inner inside the outer snake. Just a thought

Ron Gray15/10/2018 11:08:25
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@RCPF - yes it does join to the inner and I did check the flex which is negligible. Sure if I wanted the 'plane for precision aeros I wouldn't have done it that way but I prefer a heavy duty snake to the pushrod Ripmax supply!

RC Plane Flyer15/10/2018 11:19:00
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Hi again when you say heavy duty snake is that the ribbed inner I have seen in my LMS

Geoff Sleath15/10/2018 11:45:55
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Posted by Bruce Collinson on 15/10/2018 10:14:49:

Geoff,

Beware of using a butane soldering iron on your film cut line, as mine spills heat out of the side and leaves scorch marks (I attribute them to 6s LiPos if anyone asks). I found a 20W iron with a fine tip and a steel ruler very effective although there's still a slightly crinkly edge which needs ironing back down.

BTC

I used the soldering iron method very successfully. I use an electric temperature controlled iron set to 400 degrees. It's a small iron but 60 watts so it keeps its temperature as if it were a much larger uncontrolled one. I fitted the most pointed bit and just drew it along the line slowly, several times without applying any pressure to avoid scoring a line in the wood.

When I cut the slots I just sliced along the centre with a scalpel and steel rule so I was left with 2 flaps of film which I'll be able to iron back over the joint. I was very impressed by the tailplane construction when removing the film revealed a hardwood strip along the centre to increase it's strength and stiffness.

I've completed the wing. There was one small panic. After fitting the second aileron, I was sitting back surveying my work when I realised I'd fitted it upside down (I fitted the horns before fitting the assembly to the wing). Luckily the cyano I'd used on the hinges was slow enough for me to pull it out and refit the right way! I usually pin all my hinges with cocktail sticks before covering over the top. The ailerons seem quite firm but I'll be keeping an eye on them for a while and any signs of failure I'll bite the bullet and pin them. I'll just have to put with the ends of the pins showing. After all, it's not a scale model.

Geoff

Ron Gray15/10/2018 12:52:21
1447 forum posts
363 photos

@RCPF - yep, the snakes with the ribbed inners, I get mine from SLEC.

@Geoff - I had a similar experience with one I built for a club mate, the upper wing sheeting was actually the lower wing sheeting (servo holes were on the top!) and the ailerons had been temporarily attached the wrong way round. I didn't see the aileron problem until after I had fitted one then realised that the horn reinforcement wasn't in the right place by which time the hinge glue had set. Cut the hinges then Dremeled them out (had to wear a face mask due to Cyno fumes when routing out) fitted new hinges. When I went to assemble mine I made doubly sure that everything was the right way round!

Edited By Ron Gray on 15/10/2018 12:57:44

Geoff Sleath17/10/2018 00:51:04
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Well it's more or less finished. I'm hoping to test fly it tomorrow and I''ll do a brief round up once I've picked up the pieces

It weighs 5.14 lbs ready to fly with a 4S 4AH LiPo so my estimate of 5 lbs isn't too far out. The CoG is at 82 mm as the instructions say with the battery forward. I'll leave it at that to start with and perhaps move it back after I've got the feel. The only thing missing is a spinner which is on order. The 2.25" (57mm) one I have is horrible so I'm fitting an Irvine with an alloy backplate.

Geoff

Jonathan M17/10/2018 21:40:40
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Geoff, did you manage to commit aviation today?

If so how did it go?

Jon

Geoff Sleath17/10/2018 22:02:29
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Had a successful test flight followed by a couple more. It looks as though 10 minute flights will be comfortable and that's more than enough for me, so 4S 4AH LiPos will be more than adequate.

With up to 70m watts available for a 5 lb model it's not surprising the performance is good. I thought I may need to tone down the power by fitting a smaller prop but the power is quite controllable - it's there if you need it but the throttle works! There wasn't much wind today up at Ashborne (lets hope it stays that way for the scale event on Sunday) and I found it floated on and on on the landing approach. I did a few touch and goes - most were not exactly elegant but the model survived unscathed. My first attempt at a rudder elevator only induced spin resulted in a spiral dive but the second try resulted in a good fast spin which took me a bit by surprise.

The model balances at 82mm from the wing l/e with the battery well up to the back of the firewall. I found it pleasant at that but perhaps once I've got a bit braver I'll move it back.

It really is a very good kit that's generally well made and covered a lot better than I usually manage. I found the elevator halves aren't exactly matched because the holes in the wood to take the joiner are not exactly right. When I build from scratch I usually assemble the elevator halves pinned down on the board but that's not possible here unless a slot is cut. I would consider doing that if I should need to build another.

There were no screws supplied to fit the cowl. I could have lost them I suppose but in any case finding 3 suitable self tappers wasn't much of a challenge.

I used the supplied elevator push rod. It's made from a 6mm wooden dowel with 2mm pushrods inserted at each end, one threaded, te other not. However, I have a feeling it's catching somewhere and may replace it. I'm thinking of controlling the elevators with a closed loop system.

I replaced all the plastic clevises with steel and the plastic swing keepers with ball joints.

Very pleased with my impulse buy.

Geoff

Biggles' Elder Brother - Moderator18/10/2018 09:32:36
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Nice one Geoff! You can't beat a WOTTY for just pottling around in te winter. They fly really well and with loads of power will "do the book" if you're that way inclined!

I'm sure you'll have many happy flights with her.

BEB

Geoff Sleath18/10/2018 10:10:54
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Thanks, BEB. There's something I need to do before I finish the model completely and that's make it a bit more visible. I haven't got round to putting any of the stickers on but I don't think they'll help much. The mainly white scheme almost made the Wotty disappear against the slightly milky clouds yesterday. A little contrast is needed.

Geoff

Jonathan M18/10/2018 21:40:11
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Good stuff Geoff!

Geoff Sleath18/10/2018 21:49:50
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I flew it today for the first time with a spinner! I got an email this morning telling me it would be delivered. Our postie knows to bring packages to my workshop door and so it was this morning just after 10. 15 minutes later after drilling the hole out to 8mm it was fitted and my Wotty actually 'looks' finished. In fact with today's blue sky it showed up well.

Hardly worth a picture of a Wot4 but here's mine complete.

dscn2176.jpg

Geoff

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