from AEROMOD: Small but very muscular!!!
(Originally in French, automatic translation by Systran so
it might read a bit funny. f3x) par Pierre Rondel
(Originally in French, automatic translation by Systran so it might read a bit funny. f3x)
par Pierre Rondel
I tested the Aldij in these columns a few months ago, now the Miraj comes on the " scene ", developed by a binomial maintaining well-known slope pilots: Marcel Guwang and Alexis Maréchal. The clearly displayed target of this sailplane is slope soaring and more particularly F3F. In front of the enthusiasm of the designers during the first flight tests, I purchased the Miraj, which would enable me to have at the same time compact and competitive sailplane, ideal traveling companion. But let us see whether this sailplane holds its promises.
Faithful to his practice, Alexis Maréchal wanted to leave the beaten paths for this F3F sailplane by making aerodynamic, mechanical choices and construction originals of which here a non-exhaustive list:
·Small scale (2.48m) allowing to produce a mold of wing of only one part
· Profile of wing MG06 (profile reflex camber to 7.5% thickness) developed by Marcel Guwang
· Cord of aileron and flap of 30 %
· No split flap but a single flap controlled by a servos located in the fuselage
· Servos ailerons to place on the central panel and not on the tip panels
· Wings laminated without members with a carbon skin carbon of uni directional fabric 125 g/dm2
· Ailerons " emerging " (i.e. going until the end of the wing), for more response.·
· Profile of stab " double reflex camber " MG05 improving the linearity of the command around neutral.
The kit includes/understands the following elements:
· Wings in 3 parts, cut out control surfaces, wing rods installed.
· Fuselage fiberglass, stab rods positioned and pointed with the cyano, ballast tube installed.
· Stabs, control surfaces cut out, tubes installed
· Hardware package.
· 4 wing rods of carbon 8 mm
·A instruction sheet, well done with all information necessary to construction and the adjustments
· A form of appreciation to be turned over to the manufacturer (very good point!!!)
These wings are molded in only one part with the integrated sleeves and the dihedral between the central part of the wing and the tip panels. This technique of molding guaranteed an absolutely perfect fitting of the elements between them, then the wing is cut in 3 sections. Other side of the coin: it is almost impossible to change only one panel if it is severely damaged. It is necessary to order a complete wing.
The surface is very clean, even if it is not perfectly brilliant. A small blow of polish will give it the glare you wish. However during construction do not hesitate to protect your wings. Painting, of acrylic type, Acetone, white spirit, and other oil distillates are not to be used. (WD40 works great. f3x)
The rigidity of the wing is excellent, even without member, the panels connect to each other by 2 rods of of solid carbon 8mm, the ailerons and the flap is already cut out, which will avoid you this tiresome stage, it is a very good point, which one finds from now on on all the kits of the Aeromod range.
Here the list of what it remains to do on these wings:
· Locate and bore the holes of fastening screw of the wing on the fuselage. I used 4mm metal screws, even if the manufacturer recommends plastic screws of 5mm or 6mm acting of fuse in the event of crash or too hard landing. (8-32 screws and nut-plates are included in the US kits. f3x)
·Install the ailerons servos in end of central panel: Two small blocks out of wood are already embedded with the molding to receive the servos. I recommend you to use servos of 13 mm, solid and powerful (metal gears preferably): I chose HS85 BB MG by Hitec, which gives me complete satisfaction for the moment, but especially which has a reasonable price. At the beginning I tried to put MPX Micro MC of 15mm thickness, I have finally to give up, for lack of space. It is enough to dig polystyrene out between the two small blocks of wood and to place the servos there. A servo wire hole emerges at this location.
· To dig the leading edges of the control surfaces of ailerons and flap, then the fill with the micro-balloon and epoxy. The goal is to entirely close the control surfaces in order for perfect rigidity in torsion, all the more necessary since the ailerons is driven at its end. To dig, to use a small file or sandpaper, but to avoid using the point of a soldering iron which is likely to make more damage than of good.
·Dig the fields on the side of the wing so that the control surfaces can move. Indeed, the control surfaces were judiciously cut out with a bevel what avoids having to stop the slit with the under-surface, that Ci being reduced at least. Check that you have enough room, mount the control surface with two small ends of Scotch tape and move it. By my share, I have to sandpaper the skin slightly has the under-surface which hung a little the control surfaces when they moved downwards.
·Install the control horn. It is necessary to dig a small square housing of 8mm of width and depth, with a mini drilling machine, while reaching by the field of the control surface. Then bore the hole with the under-surface for the control horn. Immobilize it with a point of 5-minute epoxy, then embed it in an epoxy mixture and micro balloon. I did not use the covers with kneecaps provided in the kit, but I preferred aluminum control horn (eye screw, diameter 4 mm) from Multiplex, control horn which breathe health, on which I come to connect myself with metal standard covers of diameter 3mm. (US kits use the Multiples 4mm ring screws as control horns. f3x)
·All the finished preceding operations, it remains to make the hinges, with the Scotch tape or then by using joint silicone. It is the first time that I used this technique, on the consulting of Marcel Guwang, and I acknowledge that finally, it is very easy to make and that the result is perfect. Defer to the insert for the explanations on the installation of these hinges out of silicone.
Ah I forgot, I used to connect the wing and the fuselage a connector 6 points with locating pin MPX of green color (also exists at Jamara, red color), connector not provided in the kit.
The technique of construction is the same one as for the wings. It remains to make the hinge, installing the control horn on the elevators and a centering pin.
Alexis Maréchal consulting to use as centering pin a ball-link with ball re-entered in force and also playing the role of locking of the stab on the fuselage. For my part I used a small end of piano wire of 2mm. Are quite vigilant at the time of the positioning of the stab on the stab fillets in order to have an identical incidence for the 2 half stabs. The presence of the fillets makes the alignment easy.
The control horn are out of piano wire of 2mm bent with a cover has welded ball at the end. The control horn are then epoxy in the elevators with micro balloon.
Work on the fuselage consists of 3 stages:
To install blind nuts (not provided) for the fixing of the wing. I initially stuck them on small pieces of circuit board 3mm, then platinizes adhesive it by in interior of the fuselage, by taking care well to let dry with the wing in place, perfectly equal distance between each tip and the tail of the fuselage. (US Kits include the 8-32 nut-plates and plywood mounts. f3x)
Reinforcement of the stab rods: That are already installed, but just to point has the cyano. They should be immobilized with a mixture epoxy of chopped carbon (included). Moreover, it is a carbon tube which can break at the time of a a little hard landing. To solidify all that, I have use the technique of Olivier Aubel (thank you Olivier for the easy way!) that I will describe you: The tubes carbon meet in the center of the fuselage making it possible to pass from the carbon wicks inside. To pass a string first of all, to hang it to the wicks carbon (folded into 2 and attached to the center), " to wet " these wicks with the epoxy one, then pull the string until emphasizing the wicks on other side. Once dryness, to cross to the grinding machine what exceeds, and the turn is played! It is simple and particularly effective.
Is original, since it is about a vertical servo tray, removable, and screwed on the side of the fuselage by 2 screws. The servo tray is provided in the kit. The 2 servos (mini or micro servos, S5102 Futaba for me) for the stab are installed inverted whereas the servos for the flap (Europa BB in my case), of standard size is mounted upright. The preparation of the servo tray is done apart from the fuselage. Once the servos are positioned, epoxy servo rails of basswood to the tray. The servos are then quite simply screws on these blocks. The servo tray is fixed vertically, on the left blank of the fuselage by two wood screws, or then like me with two screws of 3 mm, of the nuts being stuck on the servo tray. (US kits include 4-40 blind nuts and screws. f3x) I also fixed the receiver (C19 Graupner) on the servo tray with two zip ties, whereas the battery (1200 mAh) comes to be placed in the nose of the sailplane with a little foam to fix it and a thermoplastic end of sheath for good to immobilize it.
The pitch controls are out of tube carbon of 5mm of diameter external (mark decathlon, free advertizing) + threaded rods of 3 mm and cover with ball side controls, metal covers 3mm side servos.
It will remain you to carry out the ballasts with the necessary form (rectangular section), who I must say it is not very practical. It would have been preferable of mold the tube has ballast around a tube of standard diameter, thus enabling us to run lead in tubes, fragments then has the good length. It is the only point during construction, or I have rager and maudit Alexis!!! My mold for ballast is out of wood, carries out for the occasion, smoked everywhere when I put melted lead, and the ingots obtained resemble Pyrenean chocolates than that of ballasts... Since Andreas Fricke, with the title of the good Franco-German agreement, gave me ballast carried out better, Merci Andreas!
The weather conditions during the first flight were not especially smoking, but allowed me to measure the sailplane. The sailplane flies naturally quickly, flap out of stringer, which is normal considering the thickness of 7,5 % of the profile. The roll is held well, even if the dihedral is small. The absence of coupled flaps/ailerons is not felt, the emerging aileron efficiency making wonder. The response in yaw is also excellent for a v-tail According to Marcel Guwang, the use of the MG05 is there for something.
If the sailplane shows an excellent smoothness out of stringer, I have a first feeling mitigated when with the flaps. The sailplane steals low tail and is inserted quickly in the dégueulante. Return to the workshop, I read again the note: ha! my values of flaps are insufficient, I were also said…
The following week, again small conditions, but this time the sailplane is perfect: the line of flight does not change when one puts the flaps and by adding small compensation to the elevator, speed decreases a little, on the other hand the wing carries much more, which makes it possible to scrape perfectly. This day there I competed with sailplanes considered as gratteurs (Ellipse 2, Dragon).Miraj show of an agility and an extraordinary precision on the axis of rolling. So that the stunt-flying becomes a treat whereas it is not at all its destination. The point rolls can be turned on the spot or more slowly, the sailplane remains on rails.
Accelerations are fast and honest, which makes it possible to launch out on a short-haul at the time of a " run " F3F.
Even if I was conceived at the beginning for a use in 4 axes, one can accomplish the same without problem. A 2 position switch is enough with a position of reflex and a positive camber position lowered by 4 mm. On the other hand this lowered position flap is essential for weak conditions in order to compensate for the low thickness of the profile. The mixing snapflap is also useful, practically under all conditions in order to increase the in turn F3F. It does not bring any side effect and makes it possible to turn tight, even when the weak conditions.
In turbulent conditions, the stability of Miraj is a considerable asset to remain perfectly on line, even very close to the slope. Besides its behavior in flight points out a little the behavior of Tempus with its elliptic wing.
The use of the ballast is not usually required because of the performances in flight of the sailplane. I would say that one will ballast later and less than with a sailplane like the tempus, or the cobra Calypso.
LE MIRAJ IN COMPETITION
To avoid having to write a judgment of the style: " this sailplane must surely be frightening in such or such category... but I did not test! ", I took along Miraj with me to Spain for the open international one of Muela close to Madrid, and this after only 3 meetings of flight. But I felt in confidence with the sailplane, and it seemed to to me that the best means of evaluating its potential was to plunge it directly in the " great bath " vis-a-vis to frightening sailplanes such as the tempus/tragi/pike/wizard compact/ellipse 3/ellipse2/V-ultra pico.
Miraj was shown with the height, being characterized once again by its agility and its stability. Even if the effect of size plays against him, its capacity to be turned very tight enables it to be particularly competitive. I encountered some problem so I decided or not to ballast the sailplane but it is because I do not know it yet enough. In spite of these small tactic errors, I finished second functioning of the podium and Marcel Guwang finishes 4th, also with Miraj. 2 Mirajs in the top 4 out of 40 pilots of which sizes of the F3F, I think that the demonstration is convincing. The following week, Miraj confirmed its potential in the Madeleine with very different conditions and much less bearing pressure.
Definitely the sailplanes coming out of the Aeromod workshops cannot leave insensitive. Miraj does not escape the rule while positioning from input from play among the best.
At the day of today, Miraj is without possible question the best performance/prix report/ratio of the market for a sailplane of slope and F3F and I weigh my words, results with the support! Admittedly, there is a little more assembly job than on a hollow molded model coming from the countries of the East, but behavior in flight is with the top of many sailplanes much more expensive. Then for those which seek a powerful machine, compact, and competitive for slope soaring, it is resolutely a good choice. I do not regret having bought this machine which gives me complete satisfaction and which I would not hesitate to take along with me to the Viking Race or during my next professional displacements to the US, history to go to make a small contest of F3Fin California...
span · envergure: 2.48 m
surface area · surface alaire: 42 dm2
aspect ratio · allongement: 14.6
weight · poids 1.7 Kg
· charge alaire: 40 g/dm2
· ballast: jusqu'à 700 g
· construction: fuselage fibre, wing full molded carbon
· prix: 3200frs
·Qualities of flights exceptional
· Compactness of the sailplane once dismounted
I liked less:
· the format of the ballasts, not easy A to make
·Fragile painting during construction
INSERT: realization of hinge out of joint silicone
Nothing easier, that takes 15 minutes for all the control surfaces, longest being the time of drying which is 24 to 48 hours approximately.
Is needed first of all attach the control surfaces places from there with transparent Scotch tape of office (that which is opaque). To leave between the control surface and the wing a half millimeter. Then to position the aileron 90 degrees and to immobilize it in this position with Scotch tape.
I use white silicone (mark crossroads) for visualizing the places well where I puts some, but it is possible to use transparent silicone.
To cut the end applicator in order to have a thread of 2 mm broad silicone on the outlet side of the tube. To apply silicone over the entire length. Then to pass the finger, to soak beforehand in water with a little liquid crockery, for applying silicone well and removing the too full one. A master key is enough.
To then position the control surface neutral, to immobilize it, then to let dry 24 hours patiently.
Once dryness, to remove the Scotch tape and the turn is cheek!!!
I assure you, it is really very easy and the result is really excellent.
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© 2000 R/C Soaring Magazine - Pierre Rondel.