Bucker Jungmann engine advice
|alex nicol||05/11/2018 16:25:40|
305 forum posts
I've inherited an almost completed Bucker Jungman. it's about 7ft span and I'd guesstimate just under 1/3 scale. It's from a pilot kit converted to the 2 seater ww11 style. it's not the lightest airframe in the world and the fuselage is mainly spruce and ply construction.
I've an ASP 1.80 fs looking for a home and was wondering would it have enough grunt to fly it. ( I'm not expecting unlimited vertical, but hoping for more than marginal)
|stu knowles||05/11/2018 16:35:04|
|574 forum posts|
My choice would be Zenoah 38/45/62
|Denis Watkins||05/11/2018 16:38:31|
|3930 forum posts|
From old graphs of capacity, power etc, am showing the 1.80 flying 22lb
And just engines shows ASP as 2.9 kw at 8500rpm
Which the leccy boys equate to 29lb
So weigh the model Alex
|Alan Gorham_||05/11/2018 16:42:35|
1069 forum posts
FWIW the original kit recommendation by Pilot was 10-20cc. A 30cc four stroke would probably be a decent match provided it fitted in the cowl OK. Remember the 2-seat Jungmann was a trainer anyway, so while it would loop and stall turn, it wasn't a hot ship like the Jungmeister.
|Antony Redding||05/11/2018 19:17:20|
|31 forum posts|
Alex, I too inherited a Pilot Jungmann earlier this year, mine came with a super tigre 3250 in it, originally it was built around a tartan twin glow (44cc flat twin 2 stroke) I've not had time to get it flown this year and I'm not sure it has ever flown on the current engine but having run it up I've no doubt it will be adequately powered.
Mine weighs around 18lbs I think so is very lightly loaded with all that wing area, plus I know the builder also built and flew a flair tiger moth on a laser 150 and that was just fine, overall the models are similar in size although the bucker has a fatter fuselage.
I've searched for a c/g for the jungmann but drew a blank but it does balance very close to plans drawn for all the smaller version of Jungmanns and Jungmeisters that I can find so I'm hopeful it will be fine as it is.
This is mine.
|Jon - Laser Engines||05/11/2018 19:35:35|
|4891 forum posts|
my 1/4 stampe is 82 inch and 16lbs. it will takeoff and fly at 1/3-1/2 throttle using a laser 180 so i think your's would be fine. Run a large diameter prop of fine pitch (20x6 of the ASP will take it) as this will give you thrust for verticals but without massive straight line speed.
|alex nicol||05/11/2018 20:57:58|
305 forum posts
looks like I'll need to do the balancing act with the bathroom scales and see what it weighs
|John Duncker||06/11/2018 16:32:54|
|79 forum posts|
My 1/4 scale Stampe flew very nicely on an OS 120 Surpass 4 stroke. Take offs from our grass strip were scale like on half throttle. The only time I can remember using full throttle for long was when I made it knife edge.
Unless your Bucker Jungman is a real lardass a 180 4st should do the job just fine.
|Peter Beeney||07/11/2018 18:55:29|
|1568 forum posts|
Just to add a few more snippets of info. about the Jungmann, it was actually designed as a primary two seat aerobatic trainer; and as it happened they did make rather a good job of it. Shortly after it went into service was somewhat overtaken, at least by sheer style and performance, by it’s slightly later stable mate, the Jungmeister, an expressly designed single seat fully aerobatic biplane of the nineteen thirties, again an extremely successful machine at doing what it was designed to to.
However in many ways, whilst the Jungmeister was very flamboyant and showman like, good at controlled flick rolls etc.*, the Jungmann was perhaps better at precise aerobatics; in later life it’s wings were given a new profile for sustained inverted flight and it gained a 180 hp Lycoming engine; in this guise it was renamed Lerche, or Lark in English, and continued to participate in aerobatic competitions up until about 1970; the Jungmister had largely ceased to become competitive in the late nineteen fifties, I believe.
*One of the superstar Jungmeister pilots was a Romanian, Prince Constantine Cantacuzino, he flew a 275 hp Lycoming version after the war and he would often perform his ‘sign off signature’ manoeuvre, simply approaching for a normal landing and when the wheels touched he would snap the throttle open, yank the plane back into the air and zip around a flick roll at about 20 feet, instantly stopping the roll when perfectly upright again and then landing on as though nothing had happened. Sometimes he would do this up to three times in a row along the runway.
Neil Williams, the RAF pilot who became British Aerobatic Champion many times, owned a Jungmann, G-BECX, and even with it’s slightly less lively125 hp engine he gave some pretty awesome displays and would finish with the same little flick rolling party trick on landing.
So I guess anyone contemplating having a go at replicating this with a model will need every last ounce of power they can squeeze out…
I’ve often thought that nineteen twenties and thirties must have been one of the best periods in history to have visited air shows. The overall flying performance was going up all the time but the rules were still pretty lax. Geoffrey Tyson, a Chief Test Pilot for Short Bros and Saunders-Roe gave an account of his routine flying program when performing with Alan Cobham’s Flying Circus and as I remember a small part of it went something like this:
‘I would fly inverted up and down over the crowd at about 30 feet, (in a Tiger Moth?), where then the people looking up could clearly see my hands working on the stick and throttle…’ Those were the days!
Good luck with that, too.
Edited By Peter Beeney on 07/11/2018 19:00:07
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