Zagi EPP

Kit Review by Trevor Hewson

(Originally written in 1999 for 'Sloping Off', the Newsletter of the Christchurch and District Model Flying Club)

My 1987 vintage SAS Thing has notched up over 350 flights and is the living proof of just what good value for money our hobby can be. Total running costs to date:- one replacement Rx battery, 2 metres of hinge tape and a squirt of epoxy to glue the fin back on now and again. Great fun though the Thing is, I was though beginning to feel somewhat left out of the foam revolution, so decided it was time to get a Wild Thing.

Conversations on the way to Sandown inevitably turned to the theme of "What are you going to buy, then?" and, when I announced my intentions, the riposte was "But you've got a Thing already". I was immediately overcome with feelings of guilt and disloyalty. Of course I couldn't bring myself to pension off the original Thing, but did I really need two? I was still every bit as keen to join in with the foam fun, so what was I to do? Then Neil mentioned the Zagi.

The Buying Experience
Now, the Wild Thing is British and the only decisions you have to take are what colour tape you want and which piece of plastic to pay for it with. The Zagi, though, is American. As anyone who has ordered a meal in an American restaurant will know, just when you think you have made your mind up, a whole new swathe of questions comes at you.

There are three variants of the Zagi on offer. The original Zagi, now known as the Zagi LE, comes with EPP leading edges, the rest of the wing being polystyrene. Having no nose, the Zagi requires a fair bit of lead to make it balance, so the use of the lighter polystyrene at the rear saves weight at the front as well. Next is the Zagi EPP which, as you might expect, is all EPP foam, an out-and-out combat machine. Latest on the scene is the electric version, based on the LE.

Price comparison is made more confusing by the fact that the LE comes with a roll of coloured tape, the glass reinforcing tape being an optional extra, whereas the EPP version is the other way round. Looking to the instruction leaflets didn't help either, since whichever Zagi you choose, it comes with instructions for the LE. Apparently they haven't had time to translate the other versions from the original American yet.

While I was trying to get to grips with this unexpected dilemma, the Eppmodels guys on the stand seemed more interested in selling me an optional tow hook and demonstrating the ruggedness of the model by beating it with a baseball bat. In the midst of this chaos, Jim's quiet observation that EPP models tend to come out too light rather than too heavy seemed like a bit of sanity worth clinging onto, so I came away with a Zagi EPP, a roll of red tape - and no tow hook.

The Building Experience
I suppose that I must qualify as a reasonably experienced builder of traditional models. However, EPP building is a totally different technique and, together with the complication of having not quite the right instructions, I felt like a beginner all over again. The first shock was in the joining of the wings. The Wild Thing has a carbon fibre kite rod as a spar, whilst the Bullit uses spruce. What does the Zagi use? nothing at all!

Now anyone can see that butt jointing two chunks of foam together without any form of reinforcement is hardly going to stand up to normal flight loads, let alone the abuse to be expected from a combat model - especially when, later on, most of the joint gets hacked away to make room for the receiver, battery and a quarter of a pound of lead. But have faith, the next step is the application of the tape, and this is the clever bit. Because of the sweepback, the two wing panels cannot be taped in one continuous strip. However, by continuing each strip beyond the centre line, the overlapping strips of tape form a herringbone pattern and so the fibres in the tape provide just the support that this highly stressed central area needs. Very neat.

On the LE version, reinforced tape is used only at the leading and trailing edges, coloured tape being deemed sufficient over the rest of the wing surface. Bearing in mind Jim's "don't worry about the weight" philosophy, I covered the entire wing in reinforced tape - and still had half a roll left over.

The instructions suggest using the foam blanks as a jig, not only for joining the wing halves together, but also while applying the tape. This is a good idea. It is all too easy to apply the tape to the bottom and then discover that the trailing edge has bowed. This is no problem as long as you press the wing firmly into its blanks while applying tape to the topside.

Apart from the Correx winglets, which are taped on later, that's it, as far as building is concerned - unless you count chamfering the leading edge of the elevons. The real work comes in the next bit.

The Fitting Experience
After the "you can't damage these models, even with a baseball bat" demo, the Eppmodels guy proudly picked up his unmarked model, only to discover that he was standing on the aerial wire, so proving the Denis Norden adage that there is no limit to human ingenuity when it comes to finding new ways of cocking things up. As he stared at the 18" of aerial wire under his foot whilst we all fell about laughing, I resolved there and then that my Zagi would have an internal aerial.

With great presence of mind, I remembered to install the aerial tube before joining the wing halves together. Being somewhat suspicious of the fumes given off when hot cutting exotic materials, I opted to make the hole by poking around with lengths of 12 gauge wire and sharpened brass tubing. This is not a good idea; EPP foam is tough stuff. Better to cut a groove in the surface and tape the aerial in that. Come to think of it, that's what it says in the instructions!

Cutting out the servo wells came next. The instructions say "Most of the colors are transparent enough to see the servo cut-out marks through the tape". My Zagi was only covered with reinforced transparent tape, but could I see the servo cut-out marks? No chance. After fretting about this for a while and holding the model at all sorts of angles under different lights, I eventually came to my senses and decided that I was quite capable of deciding for myself on a sensible position for the servos.

Is there a satisfying way of excavating servo bays out of this material? I cut out the outline with a knife which, with the wing already taped, at least ensured a clean edge. The lump of foam was then levered out. (Stan Yeo of Phoenix models recommends a dinner fork for this and I didn't find anything better!). Tidying up and adjusting the depth was done with a Minicraft drill and grinding wheel which half abraded and half melted the foam, made a dreadful mess, but did eventually result in a neat finish. A satisfactory result, but hardly a satisfying process.

All of this was repeated for the receiver bay, preceded by a bit of careful prospecting to find the end of that painfully installed aerial tube - yes, the markings for that had disappeared too. Out with the fork and grinding wheel once more for the battery bay and then it's time to link all these together. Another half hour poking about with piano wire and brass tube and the bays were all interconnected (I still couldn't bring myself to cut through the tape and lay the wires in the surface).

After cleaning up all the foam particles (EPP foam harnesses the power of static electricity to stick to practically everything) I realised that I still had to make provision for a switch. The Rx and battery bays were going to be covered over and I didn't fancy the idea of an external switch just waiting to be switched off in a mid-air, so I fitted a charging socket (inserting a plug into the socket serves to switch the Rx off.) As I cleared up the foam granules once more, the thought occurred to me that the battery bay would need further excavation to accommodate the noseweight, but that could wait a bit.

The Finishing Experience
A rummage in my Profilm box came up with enough Stearman blue to do the underside and not quite enough Stearman yellow to do the top. The top is therefore yellow panels, edged with red tape. The red tape was also used on the winglets and the elevons and suddenly the Zagi was finished. Smart, but rather dull. Continuing the 'use up the stock' theme, I emptied out my stickers bag and was confronted, not for the first time, by "Alpina Magic" in fetching shocking pink, adorned with yellow stars, and also "Akro" in gaudy red, orange and yellow. A quick burst on the computer produced two "My other plane is an" stickers and a long standing problem was solved! A sprinkling of "Safe Flying is No Accident" stickers also seemed appropriate and, with a few other bits and pieces, I soon had a very visible and cheerful Zagi which couldn't be accused of taking itself too seriously.
All that remained now was to add the noseweight, vacuum up the foam debris one more time, hook up the elevons, programme the radio and charge the battery. All-up weight, with the cg as recommended came out at 27.5oz, compared with 23oz quoted for the LE. Not bad.

The Flying Experience
The Zagi's first experience was on static display at a very damp and blustery Waters Farm Country Day. In between daring forays with the Lazy Bee, the Zagi was launched for a test glide. The test glide was fine, but the launch posed a problem - the problem being persuading anyone to do it! I will try to describe the technique. Step 1: Approach the Zagi from the front and pick it up, one handed, much as you would a tray or a bowl of soup - fingers spread across the bottom, thumb on the top. Step 2: Raise the Zagi above your head, keeping it the right way up. Any drinks waiter can do this with a tray of beer glasses in one smooth movement. Evidence to date suggests that remarkably few model flyers have served their time behind a bar. Step 3: Throw it. The problem is that it is quite clear at step 2 that it isn't going to work - but it does!

Second outing was at Ibberton - with no lift. More launching practice and test glides. Then at last a chance to fly for real at Win Green. I should perhaps say at this point that, even with a tube down the full length of one wing, the Zagi cannot accommodate a full length Rx aerial internally. I had therefore fitted an RC line 4- channel Rx bought some time ago especially for its short aerial. This Rx, although PPM, has an unusual programmable failsafe. The failsafe positions for each of the four channels are all set up using a single push button - quite a challenge. The bad news is that all these settings are lost when the receiver is switched off! Worse still, the default failsafe is 50% down elevator. I had tried this Rx in the Lazy Bee and found that it was not happy in the company of electrics, so the Zagi presented an ideal chance to use it.

Back to Win Green, and the Zagi is flying well. High speed left to right pass and - uncommanded half roll to inverted! Subsequent experiments, with less speed and more altitude, showed that whenever the right hand wing was pointed at the transmitter, the Rx went into failsafe, which on this model, resulted in 50% up on the right elevon. Better than 50% down elevator, I suppose, but still pretty disconcerting. I was though able to fly the Zagi long enough to be very favourably impressed - and to conclude it was a bit nose heavy.
Removal of 1.5oz of noseweight and fitting a Jeti 4-channel Rx have confirmed those first impressions. This is a smooth flying, very agile flying wing, recovers quickly from disturbances (whether caused by turbulence, radio glitches or mid-airs), will hover nicely for landings and, with the cg moved back, will perform reasonably inverted - although in this department, the Thing definitely has the edge.

I wouldn't like to pick a winner between the Wild Thing and the Zagi but if you already have a Thing (wild or not), the Zagi is sufficiently different and definitely performs. Any serious combat flyer should have both.