JHH A-4 Skyhawk flies at last
07-09-2006, 04:50 PM
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JHH A-4 Skyhawk flies at last
After 18 months of slow building, I test flew my Skyhawk from the JHH kit at the jet meet at Abingdon last friday. It is powered by the Wren 44, original Mk1 version with 7lbs of thrust, model weighs about 13lbs at take off. There was only time for one short flight at the end of the day but it seems promising so I can look forward to more flying of it soon I hope. The paint is Klass Kote, scheme was chosen for the bright and large colours on the tail to aid visibility, model uses 10 channels of a Multiplex 12 channel radio. The whip aerial is 500mm, that is quite a bit longer than the normal 300mm which is why it looks so long.
07-09-2006, 05:38 PM
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RE: JHH A-4 Skyhawk flies at last
Nice Scooter!! I've seen one fly before but it was a DF with an O.S. engine flew pretty good from what I can recall. How does that little wren push it?
07-09-2006, 08:08 PM
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RE: JHH A-4 Skyhawk flies at last
Harry , it's about time !!!. I've been following your progress for some time and we have comunicated in the past. Sounds like you came out a little on the heavy side so watch your turns on low power settings. I think the JHH A-4 is the ideal aircraft for the Wren 44. I've told Larry that with a few modifications he could have a top notch ARF that could compete with the Savex L-39. I have seen this airframe built as light as 8 lbs dry. I use two 12 oz. saddle tanks with good success. Keep us updated ..... Doug
07-10-2006, 07:55 AM
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RE: JHH A-4 Skyhawk flies at last
It started as the sports, not the scale, wing. I bought it third hand, partly built and the original builder had not made a good job of the wing so I scrapped it and had a foam wing cut to the same dimensions and used 4 wing servos, which is the main reason it has come out quite heavy. The longitudinal cut outs in the wing for the retracts removes most of the wing near the root so I had to ensure it had a lot of strength to cope with bending loads and undercarriage stresses.
At 13lbs take off weight the little Wren 44 with 7lbs thrust pushes it fine, when I release the brakes at the start of the take off run it fairly jumps off the line. With the new 10lb thrust gold it would be very highly powered. Due to the tank sitting in the intake duct along with the overscale intakes, and the highish wing loading causing induced drag it is rather draggy and needs a high power setting all the time to keep it moving. Smaller scale intakes and saddle tanks to reduce intake drag, along with a lower weight would allow it to go quite a bit faster I would think, and extend the flight time by allowing a lower throttle setting at cruise.
H
At 13lbs take off weight the little Wren 44 with 7lbs thrust pushes it fine, when I release the brakes at the start of the take off run it fairly jumps off the line. With the new 10lb thrust gold it would be very highly powered. Due to the tank sitting in the intake duct along with the overscale intakes, and the highish wing loading causing induced drag it is rather draggy and needs a high power setting all the time to keep it moving. Smaller scale intakes and saddle tanks to reduce intake drag, along with a lower weight would allow it to go quite a bit faster I would think, and extend the flight time by allowing a lower throttle setting at cruise.
H
