Twist – or not?

This probably isn’t going to be a conventional kit review, not because the model is unconventional but because of what I did.

So what is this, where the reviewer isn’t even sure of the model name?

Well back in late April of this year I was working at odd times around the London area and after a lousy day of meetings dropped into West London Models (Harlington, nr Heathrow). As one of the main UK agents for Multiplex they often have new items in and I just thought I would have a browse and pick up a servo.

Standing by the counter near the Multiplex radio gear I looked up and saw this group of plastic bags with model bits inside and the label ‘Dingo’. ‘Errr, what’s in those plastic bags then? What’s the Dingo?’ I asked, expecting something along the lines of odds and ends.

‘Oh it’s the latest from Multiplex, a 2m glider, it’s selling fast even though we didn’t know we would be receiving them’ was the reply.

So I had a look at the contents and to my surprise I found the bag had an epoxy/glass fuselage that was clearly the same as the now discontinued ‘Twist’ plus foam/veneer panels and a few bag of bits.

‘So what’s the price then?’, expecting something £100 plus.

‘Sixty nine quid’

Well that was it, maybe the result of a bad day at the office, but the plastic was out and swiped.

Ok, I did give it a bit of thought – I could just remember the good review the Twist had in QFI (from Keith Thomas) and I knew that Pete Hatchett has one and not only did he appear to enjoy flying it, it was also one of those models that he always seemed to have with him – the sign of a practical all-rounder.

So what is the Dingo I hear you ask. Well it is a 2m span two-function polyhedral layout glider, using plug on wings. The fuselage is slim and distinctive, with a noticeably short nose and an all-flying tail.

So why am I going on about the Twist?

Well the Twist had straight dihedral wings (about 3 degrees) with almost full span ailerons/flaperons. The wing section is RG14, so thin and potentially quick.

What Multiplex have done with the Dingo is use the same fuselage and cut the wings at about half span, the modeller having to sand in the angle to allow a dihedral break. The price has been kept down by packaging in a poly bag, but apart from that the contents are comprehensive.

My plans are probably immediately apparent – just join the wing panels, add ailerons and voila! A Twist.

So to the building – well I’m not going to go into great detail here, just a note of caution – the instructions are all in German, there is no plan (but that’s hardly relevant). There are diagrams of a few bits and pieces, which I think, suffice. This model is not for the absolute beginner; a few kits under your belt would help.

I checked out the QFI review (no 20, April/May 1996) and took note of the original comments – it is restricted in terms of installation of radio gear, and if ailerons are to be used then a very slim servo is needed.

Actual building was fairly straightforward. The major change was obviously joining the wing panels flat, but this was so easy, because they had not been pre-chamfered. I inserted a full depth 1/16 ply brace running an inch or so into each wing panel at the join, plus an inch or so of scrap carbon rod just behind the leading edge. All was glued together using 30-minute epoxy, with glass micro-fibres surrounding the braces in their oversize pockets. All straightforward and needing minimal sanding when finished. If the standard Dingo was being made then a chamfer is required and a but joint reinforced with glass cloth. I finished the wing by skinning with 70 gram glass cloth and epoxy, laying the cloth at 45 degrees on the top surface (slightly better in torsion resistance) and 90 degrees on the lower surface (better in tension). Before skinning I inserted a small hardwood block in the tips, facing with thin ply; this was to deal with the possibility of adding plug in winglets later. After skinning I cut off the ailerons, having no drawing I decided to make them 1.25 inches wide at the root, tapering to 0.75 inches at the tip, stopping six inches short of the to keep that area ‘clean’. The cut surfaces were pretty narrow so rather than fiddle with thin ply facing strips I just coated the surfaces with an epoxy/micro-balloon mix.

The tail end was superb – pre-shaped tail surfaces with joiner tubes all installed. The pivot hole is marked in the fuselage and just needed drilling out carefully, and the actuating slot opened up. All was square using the marked points. Things then get a bit tight, the rudder and tail are actuated using snakes, standard Multiplex thin wire in plastic, running in a plastic tube. A clevise was soldered onto the end of the wire and fixed to the bellcrank. The snake outer needed fixing inside the tail end, and this was fiddly, patience required with careful application of 30-min epoxy mixed with micro-fibres.

The rudder snake just fitted alongside, yes it really is that slender at the back end.

After that it was straightforward, a rudderpost added and the rudder hinged temporarily (rudder is pre shaped).

The wings are joined in a new way for me – the main joiner is a steel rod loosely located in the fuselage. The wings are maintained at the correct incidence using two wire pins each side. Actually quite easy to set up using the pre-marked guides.

Now the tricky bit – radio installation. Keith Thomas warned that it was very tight and he was right! The instruction diagram showed two small servos side by side in the nose area, and Pete Hatchett has done this with Topaz servos. I decided to follow the route of Keith T and used a Multiplex (MPX) mini BB3 servo for the elevator, maybe a bit of overkill with a model of this size. For the rudder I squeezed in a MPX MSX4 mini servo alongside the BB3. To get over the risk of clash of clevises I again copied Keith’s installation and used a ball link on the forward servo to raise the linkage. It all fitted – just! In the wings I used the special slim line MPX FL-BB wing servos; these are the thin rectangular units, only about 6mm thick. And even then they protrude slightly from the wing, even though they are installed at the root. The RG14 wing at only 6" chord is pretty thin! Pete has used Topaz servos again without any reported problems, overkill again from me, but I had the servos sitting around doing nothing (or rather waiting for another long-term project I have in mind)

A 550 mAh Nickel Hydride battery pack could just be squeezed in, and to balance the finished model I needed 4 ounces of lead in the nose, so the all up weight was 30 ounces

Flying.

This is the bit that really matters. My first flights were attempts at Chilbridge in flat calm conditions off a lightweight bungee. Hardly inspiring, it wasn’t possible to achieve any height, well although I haven’t calculated the wing loading I know it must be in the 12 ounce region, and with no breeze to help it was hardly surprising. In fact Don Brazier was struggling to get much height with his lightweight Sonata 2m. When it was off the line though the good glide angle was obvious, and the small down deflection of the flapperons looked effective. So it was a matter of patience to get to the slopes. Luckily this was possible the following week, and flying from boundary of Swallowcliffe and Oxo in a light N wind was a real joy. I need a small amount of extra nose weight, stability was initially marginal, but after that it was a joy to fly. It has a good speed range, although I have noticed that a wing will drop if slowed down too much whilst circling, well hardly surprising and after all it is not a beginners model. The rudder looks small but is very effective, rolls with my control throws aren’t fast and need down elevator during the inverted part of the manoeuvre, which is the bit I always get wrong, so you won’t be seeing nice axial rolls from me! Landing using up aileron for braking is fairly straightforward; full control is still possible.

I have knocked up some plug in winglets, nothing fancy, just 1/32 ply faced with 3/16 balsa sanded to an airfoil section (Hi-tec trainers size 8 to be precise), located with 2 short 14 swg pins pushed into tubes let into the wing tips. With these fitted I of course claim a vast improvement in performance! Actually I am convinced the circling flight benefited, plus as Don said ‘it looks good with those tips’

Overall I think I can sum up the flying as being a lot like a much larger model, say a Flamingo or Fiesta. I’m looking forward to flying it in weak slope lift, it has the convenience of small size, so lobbing it off to run up and down the slope and landing on a small patch or slope side is not a concern.

In summary I think it was an excellent buy at about £70, good quality parts and no real problems building provided min servos are used and given the minimal instructions (in German) a bit of previous experience desirable. It still don’t see why Multiplex have taken the Twist and cut excellent wings to allow polyhedral, re marketing as a ‘Dingo’; yes that choice of name is also odd to my mind. I would be interested to hear how anyone gets on with the polyhedral version; it would probably work out about 5 ounces lighter, maybe more if the wings were not glassed.

Although I bought my example from West London Models I think I saw at least one ‘Dingo’ in Spire Models a month or so ago – get out there and grab one if it is still around!