Middle Phase

Middle Phase

I must own up to a bias. I am already on record in our sister magazine Silent Flight as having said that the Middle Phase is one of my favourite aircraft for the R/C soaring beginner. I have to tell you now that neither the building nor the flying of this review has disappointed me, and being re-acquainted with this favourite was nearly as enjoyable as it was first time around!
The basic design has been available since its launch in 1976. Several modifications (usually resulting from customer feedback ) have been made, but generally, you could be forgiven for thinking Middle Phase is an outdated design. Nothing could be further from the truth however, because Chris (pictured below) pursues a rigorous policy of updating his designs each year. The instructions, for example, are very good; you get no plan, but a very comprehensive set of clearly written and drawn notes, laid out in stages, are included. Chris starts with an introduction, explains what is required to build the model, gives a list of parts in the kit (with drawings where necessary), and then provides easy-to-read and understand build notes, set out in logical sequence and completed by flying / fault-finding instructions. There’s even a BMFA application form! What of the model then?

The wings are built first, because you will need to offer them up to the fuselage during its construction. They’re veneered white foam, and are superb. Seeing them reminded me of an Ivinghoe Soaring Association member I once knew who thought he could buy cheaper when he broke his Middle Phase (after many years of abuse to the airframe). The panels he got from a well-known cutter of wings would have been better used as propellers! He had to return them on two occasions – the second time for a full refund, which he used to buy a proper set of wings from Chris Foss. Needless to say, Chris’ wings were faultless, somewhat proving the point about his extensive quality control procedure.

There are two sets of wing kits available with the Middle Phase, and I was able to obtain both: one is the standard rudder-elevator type, and the second an aileron version. These are easily interchangeable on the same fuselage.

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The standard rudder-elevator wing is by far and away the simplest of the two types to build and, including the glass-clothing of the wing join, will not take more than two evenings to finish. The panels supplied have been subject to two design improvements: firstly, tips are now veneered, and second, trailing edges are now included in the wing panels. These modifications mean that you only need to fit and shape the leading edges, check your wing root chamfer to obtain the correct dihedral, epoxy the halves together, and glass the join… easy peasy!

The idea behind including trailing edges into the wing veneer is that it prevents incorrect fitting of the traditional balsa version. In their old format, trailing edges had a habit of featuring the wrong chord-wise taper, and presented an incorrect angle between the balsa leading edge and foam panel trailing edge; these often ending up looking more like flaps than trailing edges! The new system is, quite literally, foolproof!

One important feature of these wings is a wire insert placed in the trailing edge, at the root. Don’t forget it’s there, because it will prevent crushing by the retaining bands.
Having got this far, all that remains is to cover it – in this instance, the job’s made simple by using Solarfilm.

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By nature, the aileron wing requires more work – but not a lot. The wings are not symmetrical; the section seems to be Eppler 205-ish, which improves light wind performance. By the way, if you want to ‘hot dog’ it, get a Phase 6 with the ‘professional’ wing; it’s heavier, faster, and more manoeuvrable, although much less forgiving for the beginner to aerobatics.

Leading and trailing edges are PVA glued and shaped to the profile clearly drawn in the instructions. Wing panels are joined with epoxy, and are built ‘upside-down’ on a flat building board. A root-to-tip wing taper on the underside of each panel gives an impression of dihedral, and prevents that illusion of droop that can so often spoil the appearance of flat wings. The ailerons themselves are cut to length, and the offcuts used to incorporate torque rods into the centre section. The rod ends are bent to a shape shown on the drawing which, as a point of interest, produces mechanical aileron differential offset.

Next job is to glass the centre section using some tape supplied, before fitting / shaping the tip blocks. Fashion the small aileron leading edge cut-outs that accommodate the torque rods, hinge ‘em up and, short of applying some covering, the wing’s finished. Actually, Chris provides a very useful guide to covering in the instructions, explaining each recommended system from tissue through to epoxy.

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A quick point here about visibility with an aileron equipped model. It’s fine to have one colour on your top surface and a different one on the underside but, if you intend rolling it a lot, you really need STRIPES. Stripes identify one specific surface to the eye much faster than colours. I once saw a model where the colour scheme was deliberately reversed; red top surface on the wing, with a yellow underside. Yellow top half on the fuselage, red lower half. The colour scheme acted like camouflage!

Personally, I’m heartily sick of seeing Middle Phases in red, orange or yellow, so I plumped for dark metallic blue all over, with wing stripes on upper surfaces only, just to be different!

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The ply fuselage sides, which are beautifully cut, have to be joined at (more or less) their mid point. Construction is almost ‘build in the hand’ but I would suggest that, for the basic framework of sides and crosspieces, you use a fuselage jig. Once the basic structure is formed, by the inclusion of a nose block and drawing-together at the tail, it all starts to look surprisingly complete.

Decision time, dear reader! Bolt-on wing, or elastic bands? Aileron servo in the fuselage, or wing mounted? Since this was to be a beginner’s model, I decided to fix the aileron servo in the wing, which was banded on (the wings, NOT the servo!). Banding on the wings assists ‘ding-resistance’, and minimizes rigging time. I have always been a fan of rubber band fixing, and can point to countless times where, after impact, just straightening the wings under their bands has ‘fixed’ a model. Moreover, Middle Phase has a sloping rear to the canopy, which provides an ideal ‘deflector’ if this type of accident happens.

Look very carefully at the detail sheet when it comes to fitting the fin. Room in the fuselage rear is at a premium and, if the fin base does not fit squarely, its strength will be compromised, and the angle will be very odd when you fit the rudder. Equally, the method of tailplane retention needs to be carefully assessed. You have a choice of banding it on, fixing it permanently or, doing as I did, putting ply inserts in the horizontal stabiliser for screws to pass through into the ply mounting plate.

The flying qualities of your model will be greatly reduced if the horizontal stabiliser is allowed to move about, so ensure mounting is good and solid. To avoid problems here, most modellers I have spoken to fix the tailplane in place permanently. However, I wanted mine to be detachable so that the carry case I’m going to make can be a minimal size.
Looking carefully at the build notes, you will notice that the horizontal stabiliser cross-section is not symmetrical. Plane and sand off as much as you can at the rear to get the fin, rudder and horizontal stabiliser as near as possible to the sections shown. This will prevent the need for large amounts of nose weight. Not only that, a lighter Middle Phase flies noticeably better.

The instructions show you where radio equipment should be situated in order to bring the C of G to its correct position. Now, take careful note of this very important point: NEVER fly your model with the C of G rearward of the point shown!
Chris puts a line in the instructions that reads: “now is the time to transform the fuselage into a sleek, rounded object of beauty.” Heavy stuff! Try your best though. Planing and sanding off to round the square corners reduces weight. I know some people worry about cutting into the ply fuselage sides while doing this, but I assure you the wood that remains is plenty strong enough.

And so, to covering. I picked Solarfilm, simply because most ‘first time builders’ will. It’s light, and offers an enviable range of colours. On previous models I’ve tried tissue, Solartex, glass cloth, and epoxy, but usually end up coming back to Solarfilm in the end. Take your time when covering, and the beautiful results will repay you when you watch her fly.

No disappointments in the flying department either! Middle Phase’s final weight was low, and the airfoil section, being thin and of a lifting section, inspired confidence. The weather, however, did absolutely everything it could to delay matters. I can only get to the Ivinghoe site at weekends, and week after week we either had no wind, or heavy rain. Finally, in late November, some four or five weeks after completion, we got a ‘weather window’! The wind was north-easterly, and rain was forecast late in the afternoon. NiCads on the fast charger, car pointed north, we gave it our best shot.

The model is easy to assemble ‘on-site’, and is light to carry. First flight was to be with the rudder / elevator version, so the wing with dihedral was banded on, and servo leads moved about on the receiver to make rudder the primary function. Launched into the cold north-easterly, Middle Phase tracked out without any changes to either rudder or elevator. I started ‘essing’ her in front of me, to gauge the effectiveness of both controls. Too much rudder, not enough elevator, so I landed and made some necessary clevis adjustments on the tail surfaces. After re-launching, it soon became obvious that the controls were much better, being much more harmonised and effective. We took some photos, and I looked about for a beginner…

I soon found, assembling a ‘Gentle Lady’, one Andy McKinnon of Milton Keynes. He needed no encouragement at all to accept my offer of a flying lesson on Middle Phase, and was only really worried by the MC20 transmitter! He flew for some fifteen minutes, and described the experience as ‘effortless’. His colleague Alan (never did get his last name) then took over, and flew a further ten minutes.

Needless to say, both fellas ended their flights with smiles on their faces. Giving the tranny to Paul Wilson provided the day’s only drama. Upon seeing another model getting awfully close, in the slope’s narrow band of lift, he pulled UP when he should have used the rudder. The subsequent low altitude stall brought Middle Phase into contact with the slope on a wing tip. No major damage was sustained, although we did have an off-square horizontal stabiliser (it moved on the retaining screws), and an askew wing under the elastic bands.

On with the aileron wing. We didn’t really have enough wind to assess this version properly, but one thing which did become clear immediately was that, being as light as it was, Middle Phase was dealing with the low wind, tight lift area situation very well, and was easily out-climbing the other models present on the slope at that time.

I looped, rolled, stall-turned, and flew inverted… no complaints in these conditions! The stall-turn looked particularly good, using the BIG rudder. It must be noted that, because this model is so light, and has a wing section that is not symmetrical, it simply cannot ‘fly the pattern’ like, say, a Phase 6. The beauty of this aeroplane is that it can handle light lift situations and, for the most part, this makes it ideal in the UK. ‘Old-uns’ like me will remember that, in the old days, slope aerobatic competitors often finished their run at the foot of the slope if conditions were anything less than perfect!
The aileron version of Middle Phase sacrifices the cutting edge of aerobatics in favour of easy handling, and the ability to fly in just about any wind, from 2.5 to 25 knots. It is forgiving and virtually stall free, unless horribly provoked, and makes a beginner feel more confident from the outset. As mentioned in the introduction, I hold a special affection for this model, and reviewing it has reminded me of the pleasure gained first time round. I would not hesitate to recommend it to any beginner.


Name: Middle Phase
Aircraft type: Glider trainer
Manufactured by: Chris Foss Designs
Available: Direct, or from your local stockist
RRP: Primary £70, Advanced £75 (street prices June 2011)
Wingspan: 61”
Wing area: 440 sq. in.
Wing loading: 11 oz / sq. ft.
All-up weight: 2 lb 2 oz.
Rec. no. of channels: 2/3
Control functions: Rudder, elevator, optional aileron
Radio requirements: 3 standard servos

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