MIRAJ from AEROMOD

"The french F3F touch"

by Pierre Rondel

 

INTRODUCTION

The Miraj, a newcomer on the slope scene, has been developed by two soaring enthusiasts: Marcel Guwang and Alexis Maréchal. The clearly displayed target of this sailplane is slope flying and more particularly F3F. In front of the enthusiasm of the designers during the first test flights, I let me convinced to purchase this glider, which would allow me to have, at the same time, a compact and competitive sailplane, the ideal travel companion. But let us see whether this sailplane holds its promises.

AN ORIGINAL CONCEPT

Once again, Alexis Maréchal wanted to be creative for this new F3F sailplane by doing original aerodynamic, mechanical and building choices like: · Small wingspan (2m48) allowing to build a one piece wing mold.

The kit includes the following parts:

       
   

 

   

MG06: A new section is born !

This brand new section has been designed by Marcel Guwang especially for the Miraj and F3F. This is a thin section 7.4 % with an correct camber (2) to use with 30 % flap chord. I joined different polars to show you that the results are interesting. The section works great for low Cz and in addition is also really good for a low number of Reynolds. Last but not least, the MG06 accepts very well the flaps down.

 

WINGS

These wings are molded in only one part with the wing joiner tubes in place and with the correct dihedral, then cut in 3 panels. This molding technique guarantees an absolutely perfect fitting of the 3 elements together. But the drawback is that it is almost impossible to change only one panel if it is severely damaged. The surface is very clean, even if it is not perfectly brilliant and not equivalent to (much) more expensive planes coming from eastern Europe. But it's possible to obtain a more brillant surface by using polish.

Do not hesitate to protect your wings during construction, because the paint (acrylic type) is really fragile. Never use acetone or white spirit, and other oil distillates. I recommend WD40 instead, which works great. The wing stiffness is excellent, even without spar, and has a good torsion rigidity. Panels connect to each other by two 8mm carbon joiners. The ailerons and the flap are already cut, which will avoid you this tiresome stage. It is a very good point, we can now find on all the Aeromod product range. Here the list of what remains to do on these wings:

 

 

THE TAIL

The construction is identical than for the wings. It remains to make the hinge, and make and install the elevator torque roll ball end plus a alignment peg on each half tail. Alexis Maréchal advises to use as alignment pegs a ball end entered in force in the fuselage and playing the role of locking the tail on the fuselage. I preferred to use a small piece of 2mm piano wire and lock the tail in place with a small piece of tape. However, be careful when positioning the tail on the fuselage in order to have the right V-angle (with the wings), even if the presence of the karmans makes the alignment easier. Elevator torque rolls are made with a piece of 2mm piano wire bent with ball ends. they are then glued in place in the elevators with epoxy and microballoons.

       

 

 

 

THE FUSELAGE

The joint line is not perfect, but the fuselage is light and very strong. The work mainly consists in the radio installation and wing fixation.

  • To install nut plates (not provided) for the fixation of the wing. I initially stuck them on small pieces of 3mm epoxy circuit board (plywood works also great), then glue them in the fuselage, by taking care to let them dry with the wing in place, with a perfectly equal distance between each wing tip and the tail of the fuselage.
  • Reinforce of the tailplane joiners: That are already installed, but just immobilized with a drop of cyano. They should be reinforced with a mixture of epoxy and microballoons. however, this is just a 6 mm carbon tube which could break during a very hard landing. To make them almost unbreakable, I followed the technique from Olivier Aubel (thank you Olivier for that easy way!) that I'm going to describe to you: The carbon tubes meet together in the center of the fuselage making possible to pass carbon locks inside. Pass a string first of all, then attach it to the carbon locks folded into 2 and attached at the center. Wet these locks with the epoxy, then pull the string until the locks exit on other side. It's simple and particularly efficient.
  • Radio installation is very original, since it's a vertical keel, removable, and screwed on one side of the fuselage by 2 screws (The keel is provided in the kit). The 2 servos (15 mm mini or 13 mm micro servos, S5102 Futaba for me) for the tailpane are installed inverted whereas the servos for the flap (MPX Europa BB, standard size in my case), is mounted upright. The preparation of the keel is done apart from the fuselage. Once the servos are positioned, you just have to install and glue small wood blocks on the keel. The servos are then simply screwed on these blocks. The keel is installed vertically, on the left side of the fuselage by two wood screws, or like me, with two 3 mm screws, two nut plates being stuck on the servo tray. I also fixed the receiver on the keel with two zip ties, whereas the battery (1200 mAh) is placed in the nose of the sailplane with a little foam and a piece of thermoplastic sheat to immobilize it. The elevator pushrods are made with 5 mm carbon tubes and 3 mm threaded rods and equiped with 3mm ballcups, and 3mm metal clevises on the servos side.
  • To finish, you will have to prepare some ballasts with the correct shape (rectangular section). I must admit that I hated this operation and I think it would have been preferable to use a tube with a circular section instead ! My ballast mold was made of wood, and it smoked everywhere when I put melted lead in it, and the ingots obtained looked like Pyrenean chocolates (you know ? with aluminum paper!) than ballasts... Fortunately, a friend of mine, Andreas Fricke, gave me 3 beautifully made ballasts, around 245 g each. Thanks a lot Andreas!

 

THE MIRAJ IN ACTION

The weather conditions during the first flight were not especially good, but allowed me to have a first feeling about the sailplane. The sailplane flies naturally quickly (which is normal considering the 7,5 % thickness of the section) and in silence compared to hollow core moulded plane. The spiral is easy, even if the dihedral is weak. The absence of quadroflap is not a problem, the ailerons working wonderfuly. The handling on the other axis is also excellent for a V-tail. According to Marcel Guwang, the use of the MG05 (double reflex section) is the reason. However, I have a first moderated feeling with the flaps down. The sailplane slow down and had a important sink rate.

At my return to the workshop, I read again the building instructions and discovered that my setting for the flaps was insufficient, shame on me !!! Conclusion, please follow the building instruction and especially the paragraph about settings up !

The following week, with once again a poor lift, the plane has changed radically when using the flaps down (and small elevator compensation): the trajectory does not change, the speed decreases a little, on the other hand, the wing lift is much more better, which makes it possible to thermal perfectly. Miraj shows an extreme agility and an extraordinary precision on the roll axis.

Aerobatics is very easy whereas this is not at all its predilection domain. The 4 steps roll can be turned straightaway or more slowly, the sailplane remains on rails. Accelerations are really good, which makes possible to "launch" the plane on a short dive at the beginning of a F3F run. Even if the Miraj has been designed, at the beginning, for a use in 4 axis (so with a dedicated radio stick for the flaps), there is no problem to use it with a simple 2 positions switch: normal (neutral) position for speed flight or aerobatics and flap down for thermal flight.

The snapflap mixing is also useful, practically under all weather conditions in order to increase the lift during tight turns and, this, without any side effect. In turbulent conditions, the stability of Miraj is in considerable asset to remain perfectly on the trajectory, even very close to the slope edge. Besides its behaviour points out a little the behavior of the Spanish Tempus with its true elliptical wing.

The use of the ballasts is disconcerting at the beginning, because of the flying performances and the very thin section. I would say that the use of ballasts comes later and in smaller quantity compared to bigger planes like the Tempus, or the Cobra Calypso. The Miraj can carry up to 700g of ballast.

WHAT ABOUT COMPETITION ?

In april 2000, after only 3 flights of 30 minutes, I took my Miraj with me to Spain for the international F3F open of La Muela close to Madrid. But I was confident with the plane, and felt that the best way to evaluate its potential was to confront it to other well known and competitives sailplanes such as the tempus/tragi/pike WR/wizard compact/ellipse 3/ellipse2/V-ultra pico.

The Miraj was not ridiculous at all, being characterized once again by its agility and its stability. Even if the scale effect plays against it, its ability to turn very quickly and its good energy retention allowed to the Miraj to remains very competitive. However, I encountered some problem to decide when or not to ballast but it is more because I didn't know it yet enough. In spite of these small tactic errors, I finished second and Marcel Guwang finished 4th, also with a Miraj. 2 Mirajs in the top 4 with 40 pilots (including well known top F3F pilots!), I just hope that the demonstration is convincing enough. Since "La Muela", I used my Miraj all the 2000 F3F season and won the french F3Fchampionship (2nd rank, 1st, 1st, 3th, and 1st) in very different lift conditions going from the light breeze to strong wind.

 

CONCLUSION

Sailplanes coming out from Aeromod's workshop cannot leave insensitive. The Miraj does not escape to the rule and play, from the beginning, among the best. Today, the Miraj is, for sure, one of the best price/performance ratio on the F3F scene.

It's true that there is some extra work compared to a product from the Eastern of Europe, but flying performances are better than many more expensive sailplanes.

So if you are looking for an excellent plane for slope sport flying or F3F competition, the Miraj is a good choice you should consider. In conclusion, I do not regret my purchase which gives me lot of satisfaction.

CHARACTERISTICS

wingspan: 2.48 m

wing area: 42 dm2

aspect ratio: 14.6

weight: 1.7 kg

wing load: 40 g/dm2

ballast: up to 700 G

price: 350 £

manufacturer: Aeromod

snail mail address: Aeromod / Pyrenees Modeles, 16 Avenue Larrieu Thibaud 31100 Toulouse, FRANCE

web site http://www.chez.com/aeromod

 

 



 
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Copyright © 2000 Planet Soaring - Pierre Rondel.
No commercial use or publication (e.g. on other www or ftp sites, print media) without a written consent.


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