Modelo ensaiado por Brian Austin / Model reviewed by Brian Austin (see English version below)

 

 

Em 2010 um jovem piloto eslovaco, Marko Gala, voou e venceu o equivalente britânico da Taça Nacional com um Stork 4 de cauda em cruz, onde sopraram ventos bastante fortes, como tal pareceu-me uma boa escolha para um novo modelo, já tinha ponderado numa nova aquisição já que não estava muito satisfeito com o que voava na altura. Dito isto, finalmente consegui configurar o meu Xperience Pro e agora até voa muito bem.   

Após investigar se o Stork estava disponível descobri que duas versões, o Stork 3 e 4, existem nas variantes F3J e “eléctrico”. Note-se que a asa da variante “eléctrica”  tem uma construção em fibra mais ligeira e que não permite o reboque manual ou por guincho. É bom que o fabricante se tenha dado ao trabalho de fazer duas versões da asa para as duas variantes, a maioria dos fabricantes não se preocupa com isto já que vendem tudo aquilo que produzem!

 

Após usar servos Hyperion nunca mais usei servos de outra marca dado que são potentes, pequenos e fáceis de instalar, particularmente os servos digitais para instalação na asa do tipo DS 095. Outra vantagem é que podem ser programados para ter 70⁰ de curso para cada lado do neutro num total de 140⁰, isto pode ser útil no caso dos flapes em que é preciso bastante batimento da superfície para utilização em mistura de freios tipo “crocodilo”.

 

O motor recomendado pelo fabricante é um Hacker B40-L6 sem escovas e com redutora 4,4:1 mas este motor não é propriamente barato e como não pretendia uma razão de subida de 15m/s como o tal modelo do Marko Gala procurei algo mais em linha com a minha carteira. Tal como nos servos, também prefiro os motores eléctricos Hyperion e depois de ler as especificações pareceu-me que o motor de carcaça rotativa sem escovas GS3025-8 seria adequado, actuando um hélice Aeronaut CamProp 15” ou 16”X8” e utilizando um variador de 80 ampère com um BEC de 5 ampère.

 

Por pura sorte, enquanto percorria a eBay encontrei precisamente um GS3025-8, fiz uma licitação que ganhou o motor por £28! Mas mesmo que compre um motor novo o preço anda na ordem das £58 (cerca de €67), bem menos que o preço sempre crescente dos Hacker ou Kontronik, por exemplo um Kontronik Kira 480 com redutora 5,2:1 custa actualmente cerca de €205.

 

Os servos que usei na fuselagem foram os Hyperion DS11, que são um pouco pequenos para as aberturas existentes, os servos Futaba S3155 recomendados pelo fabricante encaixam perfeitamente (Note-se que os Stork “electrificados” tem dois pequenos compartimentos na fuselagem e atrás do bordo de fuga para o receptor e os 2 servos para a cauda em V, isto facilita a instalação da motorização e reduz peso – R. Silva). Usei um receptor 35 MHz  Schulze 835 (sim, já sei que devia mudar para 2,4 GHz) com a antena instalada no tubo previsto para o efeito e com saída no extremo posterior. A fuselagem é “compatível 35 MHz” dado que a parte posterior à asa não tem fibra de carbono.

 

Em 10 dias de trabalho descontínuo montei o modelo (não se pode chamar construir a isto!), o piso é ficou aproximadamente em 2,2 kg, o que não é mau para um modelo compósito, o Mistral pesa 2,1 kg e tem as pontas das asas em estrutura clássica. Para aqueles que gostam de saber os pesos dos componentes aqui tem: cauda em V 86 grama, painel esquerdo 225 grama, painel direito 222 grama, painel central 669 grama, fuselagem 690 grama e bateria Kokam LiPo 3s de 2400 mAh 227 grama.

 

 

A 1ª tentativa de voo foi um anti-clímax, o hélice soltou-se, a primeira vez que tal me acontece, na 2ª tentativa o Peter lançou o modelo e aquilo subiu que nem um foguete, dissipando qualquer dúvida que a potência não fosse suficiente. O hélice fazia de molinete porque não programara devidamente o variador, mesmo assim o ângulo de planeio era excelente. Considerando que o vento estava pelos 10 ou 12 nós o modelo voava bem, apenas aumentei o “trim” da profundidade para o modelo penetrar melhor.

 

Termino escrevendo que sem dúvida é o melhor modelo moldado que já voei, sendo bastante fácil de voar e sem derrapar nas voltas como muitos dos modelos compósitos fazem. Estou convencido que isto se deve ao razoável diedro alar e possivelmente ás pontas das asas “em flecha”. Lembra-me o Alacrity de vários modos, até no comportamento com os freios em que pode descer muito rapidamente e sem qualquer dificuldade.

 

Características do motoplanador Stork 4:

 

Envergadura: 3,56 m

Peso: aproximadamente 2,2 kg, dependendo da motorização, etc.

Área alar: 73 dm²

Carga alar (a 2,2 kg): 30,1 g/dm²

Perfil alar: mantido em segredo pelo fabricante!

Controles: Cauda em V (dois “ruddervators”), dois flapes, dois ailerons e motor.

Preço: aprox. €1000

 

O melhor do modelo:

Fácil de montar

Muito fácil de pilotar

Um bom modelo para competição

 

O pior do modelo:

Ligação dos servos asa/fuselagem trabalhosa

 

Fabricante/vendedor (Eslováquia): Heinrich http://www.heinrich.sk/

 

Marko Gala flew a cross-tail Stork 4 to good effect at the British Nationals in 2010, where the wind was very strong, so it seemed to be a good model; I had thought about getting one before as I was not always happy with the ones that I was flying at the time. Although having said that, I have finally sorted out the Xperience Pro which now flies very well.

 

Having investigated as to whether the Stork was still available, it came to light that 2 new versions, the Stork 3 and 4, are available in both F3J and electric configuration. It should be made clear that the electric version has a lighter lay up wing that should not be used for winch launching. Still it is nice to see that the manufacturer has gone to the trouble of making different lay ups for the two disciplines. Most cannot be bothered as they say they can sell all they make!

 

My friend Peter Hindle and I ordered 2 Stork 4’s in the autumn of 2010 and they were to turn up in October 2010. The quality of the components was first class, with all hardware included (other suppliers take note), push rods fitted with linkage, etc. I did not have to fettle joiners, which made a change and all the plugs to connect servos in the wings and wing to fuselage are included. I would say that the Deans type of plug used for the wing to fuselage connection is a lot more fiddly to wire up over the more normal 9 pin PC plugs used as you have only 6 pins on these, so 4 wires going to one pin is out, as is normal on the “+” and “-“ wires on the servos. I made it up similar to a Y lead from each wing half to connect to the plugs.

 

Having seen and now used Hyperion servos, I would not use any other from now on as they are powerful, small and easy to fit, particularly the DS 095 digital wing servos. Another plus is that they can be programmed to give 70 degrees of throw either side of neutral making 140 degrees in all; this can be useful on some flap set ups where you might need a lot of movement to meet the crow brake demands.

 

The motor specified is a brushless inrunner Hacker B40-L6 with a 4.4 gearbox but these are not cheap and as I was not after a climb rate of 3000 fpm that Marko Gala uses for FXJ something more in line with the pocket was sought after. As with Hyperion servos, I have come to like their electric motors as well; having looked at the bumf on them it looked as though the GS3025-8 brushless outrunner would fit the bill, driving a 15”X8” or 16”X8” Aeronaut CamProp, coupled with an 80A ESC with a 5A BEC.

 

By shear luck I was trawling through eBay one day and came across a GS3025-8, I made a bid which won the motor for £28! But even if you buy one new they are only £58. A bit different to Hacker or Kontronik, which seem to be going up in leaps and bounds, a Kontronik Kira 480 with a 5.2 gearbox is now about £170.

 

Peter decided to copy me and go for the GS3025 as well but was worried that there was not enough clearance for the motor wires where they passed close to the revolving case of the motor, it being an outrunner. So I made up another motor mount former out of thicker fibreglass board, some 2mm plus thick, brought the 3 wires from the motor and aligned against one another, then passed some heat shrink over them, to hold them flat. There is a blister on one side of the electric fuselage, to help outrunner wires to fit the fuselage and this is just enough to clear them. To make sure they stay there, I then “Evostuck” the wires to the fuselage after the motor was screwed in. It is worth pointing out that there is a depression on the opposite side to the blister for the wires, that can be cut away to allow cooling. I would advise this on the motor I used as it can get noticeably warm.

The fuselage servos I used were Hyperion DS11’s which were a bit on the small side to fit the apertures in the fuselage, the recommended Futaba S3155 servos would fit exactly in the spaces provided (Note that the “electric” Storks have two small fuselage compartments behind the trailing edge for the receiver and the 2 V-tail servos, this eases the powertrain installation and reduces weight – R. Silva). I used a Schulze 835 35 MHz receiver (yes I know I should go 2.4 GHz) where the aerial slides down the tube provided to exit at the rear. The fuselage is 35 MHz friendly as the rear end has no carbon in it behind the wing.

 

The whole thing went together in about 10 days of off and on assembly (you can’t call this building!), weight is approx 2.2 kilos which is not bad for a fully moulded model, the Mistral weighs in at about 2.1 kg with built up tip panels. For those that like to know the component weights are: V-tail 86 g, left tip 225 g, right tip 222 g, centre panel 669 g, fuselage 690 g and Kokam 2400 mAh 3s LiPo pack 227 grams.

 

Wing area is 1131 square inches (73 dm²) so I make the wing loading just under 10 ounces per square foot (30.1 g/dm²). I set the model up as recommended on the Heinrich site for the throws and CG position and checked out the watts at 650 which were OK for the motor specs.

 

First attempt was an anticlimax as the propeller flew off, first time for everything I suppose, as it had not happened to me before; on the 2^nd attempt Peter launched the model, whereby it climbed like scalded cat, so much for the worries on not enough power. The prop was wind milling due to the brake not being set properly, so glide was impressive with that drag. Considering the wind speed was about 12-14 mph it performed well. I increased the down elevator for speed trim which helped to drive the model forward.

 

Finally I would say without doubt it is the nicest moulded model I have flown, being very easy to fly, with none of the sliding in on turns that so many of them exhibit. Pretty sure this is due to the fair amount of dihedral on the wings and possibly the “swept” tip design. It reminds me of my Alacrity in many ways, even to the crow braking behaviour, where it can be brought down very quickly from height with little fuss.

 

Stork 4 motor glider data:

 

Wingspan: 3.56 m

Weight: circa 2.2 kg, depending of propulsion drive, packs, etc.

Wing area: 73 dm²

Wing loading (at 2.2 kg): 30.1 g/dm²

Wing airfoil: kept secret by the maker!

Controls: V-tail (2 “ruddervators”), two flaps, two ailerons and motor.

Price: approx. €1000

 

The best of the model:

Easy to put together

Very easy to fly

Good competition model

 

The worst of the model:

Fiddly plug to join servo connection to wing from fuselage