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Gary Clemans-Gibbon 
reviews the
Luna 400TM
 from Flying Wings
Flying Wings is a Norwegian business specialising in the manufacture of simple, inexpensive foam flying wings. The range includes the V-tronic (slow flyer, indoor, electric), the Tempra2 combat model (slope sailplane) featuring an EPP leading edge and the Luna 400 which is the subject of this review. The Luna can be built as a slow fly or fast (depending on motor/battery size). It also makes a good self- launching thermal soarer and if built really light could be used indoors (although the V-Tronic is specifically designed for indoors!). The business is owned by Kjell-Arne Fjelde who says of the indoor version "The winters here in Norway are too dark, too cold, too long and too windy to fly outside."
Here we concentrate on the Luna 400. This very simple white foam flying wing uses a standard (or Speed) 400 sized electric motor, a 14-20 amp speed controller and the recommended flight pack is anything from 8x700mAh, 8x800mAh to the brand new CP1300SCR cells from sanyo (these weigh 2 grams more pr cell than the 800mAh cells, but give 60% more duration).
Being a flying wing there is no fuselage, making it simple, fast and cheap to build. It needs three radio channels (elevons and throttle) and requires a mixer to mix the elevator and aileron to give elevons. Any computer radio will provide this function. For non-computer radio users a cheap electronic mixer can be purchased for around 10 from a model shop.
Read on for building tips and the results of the flight tests.

What you get


Picture courtesy Flying Wings

The wings are very accurately cut from white foam using a CNC cutter and come packed in their foam block outers. The surface is already pretty smooth and requires only a very light sanding before covering. Unfortunately I had already joined them (with copydex type contact adhesive) before I thought to get my digi-cam out.
The elevons (ailevators?) are simple sheet balsa, the spar is a hollow 6mm carbon rod and all the necessary pushrods and horns are supplied as are the corex winglets (not shown).
You need to supply two (preferably micro) servos, receiver, 400 size motor, flight pack (I used a small and lightweight 7x500mAh cell pack), a 20 amp speed controller, coloured covering tape (I also used glass weave tape for added bounceability).


Building

Picture courtesy Flying Wings

At the time of the review the instructions were only available in Norwegian so I rather "winged it" (pun intended) through the construction process. Nothing here is cast in stone, if it looks right - it is right!
Mark the positions for the spar and propeller cutout as shown.




As I mentioned before, the kit comes with a hollow rod 6mm carbon spar but I managed to lose mine so here you can see an improvised thin (approx 1.5mm) ply spar. Note the taper to save weight and to keep from protruding from the slim wing's surface.
The balsa spar I made up seen lying along the right hand leading edge was discarded in favour of the ply one.




Here you can see the spar sunk into a groove cut into the underside of the wing. Also cut two reinforcing plates from 1/8th balsa as shown.

 

Picture courtesy Flying Wings

With the wing upside down position the servos in front of the spar (equal distance from the centerline) and mark the position. Make sure you allow enough servo lead to meet in the center for the receiver! When happy cut out the rectangle for each servo.




Top view of the wing with the reinforcing plates glued on. Note the small balsa ridges which will help to support the motor. All gluing of foam to foam and foam to wood was done with contact adhesive. A thin smear is applied to both surfaces to be glued and left for ten minutes or so (or until clear) before bringing together. Wood to wood gluing was done with cyano.




Next the elevons are top hinged using glass weave tape. Using a razor plane or a sanding block the lower leading edge corner of the elevons was shaved off so that full down movement could be achieved. A useful tip here is to apply the tape to the top of the wing first and then lay a thin spacer along the trailing edge before bringing the elevon up to the tape. I used my steel rule for this. The elevon is then folded over to lay flat on the top of the wing while the bottom strip of tape is applied.




Top view of the wing with one servo installed. Note the shallow groove to accommodate the servo lead. Apply some reinforcing tape to the leading edges as shown.




Here you can see the lovely mess I had made of the kitchen!
Important safety tip: clean it all up before the wife gets home!




The position of the elevons doesn't seem to be critical other than it is symmetrical. Here you can see how I positioned them. This contributes to a unique and rather pretty plan form in flight.




View of the underside. OK so I went a little mad with the glass weave tape - but each individual strip felt soooo light! Later I was to be glad I had wrapped it up so well.




Another view of the underside. This time the two tie wraps used to hold the motor in place are visible.




Now add the corex winglets using thin strips of - guess what - glass weave tape top and bottom. This also provides an aerodynamic fillet to reduce drag. (Right!)




Next, flip her over (ohh err Mr Grimsdale) and go colour crazy with the colouring tape (available with your Luna here. As well as helping with visual orientation in the air, this protects the glass tape from UV sun damage. I left the underside alone.




Here you can see the position of the NiCad. It is simply stuck in place with tape. The final position can be determined after a few test flights.




The finished article complete with push rods (note they are at 90 degrees to the hinge-line at the expense of a tiny amount of drag) and showing the slight hollow I carved to seat the battery pack in.




The receiver and speed controller are simply stuck on to the wing between the motor and the battery with double sided tape. The receiver aerial is carefully routed around the prop cutout and taped along the trailing edge of one elevon. Any excess left over can either be left to dangle in the breeze or threaded forwards and backwards through the holes in the corex winglets. I prefer not to have too much dangling to prevent stepping on the dangling aerial. A final strip of tape over the electronics keeps any servo/power leads wires from fouling the propeller.


Trimming, balancing and flying.
I took the setting up very seriously and did it while my tranny was on charge! I lifted up the elevons by about 3mm at the trailing edge and hooking my first and second fingers up and around either side of the motor from underneath gave it a nice firm push forward at a slight downward angle. Perfect. I would only recommend this method if you used as much glass tape as I did though!
Transmitter charged and on, elevons programmed and flight pack charged it was time for the off. Using the afore mentioned lobbing technique (throttle OFF!) I launched it. The glide is so good that you have plenty of time to get your hand to the throttle stick to give it some power and off she goes. The climb rate is good and with maxi throws on the elevons rolls are fast and easy. In fact it is easy to do a roll from the launch BEFORE adding power!


Conclusion
This is a super fun model which takes around two to three hours to construct (depending on how much tape you use and how fast you are). If built for use as a slow fly or indoor model I would recommend that the weight really be kept down - minimal glass tape (just wing join, elevon hinges and leading edges), a 270 motor and tiny NiCad. In the configuration I chose it is a superb general fun model, aerobatic and capable of handling a medium breeze (more than my Twinstar). What's more it is a very efficient glider with good penetration.
I have a couple of 1300 mAh NiMh packs that I use in my Pico Jet and I'm looking forward to trying one of those out in the Luna.
With the small battery I used I was getting flights of six to seven minutes with power on (but if you find a thermal this can easily be extended). This is one for those summer days thermalling and without the launch hassles of a regular glider. Due to the low investment in time and money this is a real fun machine and if you do get it wrong it is surprisingly bouncable. A must have model!


Prices
The following prices are in British Pounds (other currencies and postage costs available on request).

Luna standard version 23.00
Luna EPP version (EPP LE) 27.00
Tempra2 23.00
Coloured tape 3"wide, 55 Yards Long 4.50
V-Tronic wing 12.00

P&P from Norway to the UK is around 12.00. (Packages over 5 wings is around 5.00 more expensive)
Get further details and see some videos and pictures of the wings in action at the Flying Wings Website
Send Flying Wings an E-mail E-mail

Gary Clemans-Gibbon
2 July 2001 All rights reserved


 

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