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Author Topic: Keil Kraft Polaris  (Read 1254 times)
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JB006+3/16ths
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« on: June 25, 2017, 05:50:38 AM »

Here's my second attempt at the Polaris, last one 8yrs ago which showed looping tendencies ended up in retirement. This one does the same but I am going to try some tail leading edge up to reduce the incidence.
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Keil Kraft Polaris
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Hepcat
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« Reply #1 on: June 25, 2017, 07:53:13 PM »

JB1935.

Don't waste your time trying trying to trim the stupid thing, the moment arm is too short to ever make a flying machine.  Give it to some small child, they think it is fun when every time they throw it it it swings round and hits them on the head.   I do realize that a catapult glider is the best aeromodelling fun you can get for two bob but just find a recent plan and build your own.  In the 'Polaris' era I think the kit manufacturers designed a box first and then filled it with offcuts from the last garden fence they made. I am sure modern kits must be better but I haven't bought one since the 1940s.

John
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John Barker UK - Will be missed by all that knew him.
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« Reply #2 on: June 25, 2017, 10:51:34 PM »

JB006.188

Sadly, the esteemed Hepcat's prognosis is basically correct, if a little bit pessimistic.
I built a similar vintage HLG design some years ago (a Hervat or somesuch) and it flew reasonably well for many years. Hepcat's advice to pick a more modern design is spot on, really, and you might want to search for Mick Page's Butterfly design and the Aeromodeller article that went with it as a path to much better performance.
The Polaris could be made to fly,  but if you want to cure the looping tendency  you will need to bend the trailing edge of the tail down, not up, and move the balance point aft a little to restore the glide.
John
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« Reply #3 on: June 26, 2017, 08:41:15 AM »

Glidermaster John.
That was a brilliant pick-up on the JB number.  I thought I was being clever but to be topped on the very next post leaves my ego sadly deflated.  I promise i'll never criticise another KK Kit (but then my promises are like piecrust).
Hepcat John.
 
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« Reply #4 on: June 26, 2017, 10:04:05 AM »

At least Hepcat got me laffing this am Angry Sad Grin
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JB006+3/16ths
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« Reply #5 on: June 26, 2017, 04:27:12 PM »

Anyone noticed how many people in this topic are named John?.
I know it is probably a bit of a lost cause but I don't like being beaten by things. Last night I did try a wedge under the leading edge and it will fly in reasonable left hand circles with a flat launch and not hoofing it too much. As soon as the launch involves right bank it all goes pear shaped. Never mind it's already performing better than the last one.
As for the Butterfly I have one of those that I inherited and it flies really well when I get the launch right.

John
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« Reply #6 on: June 27, 2017, 01:03:00 AM »

Well John here is another John.

What would the world do without Johns Smiley

Hepcat John is correct re these old HL Gliders. Although I always suspected they were in a competition to have the greatest number of shapely curves.(curvaceous objects seem to have been very popular during the time they came onto the market Smiley

They sometimes have a nostalgic appeal but this seems to have been achieved at the expense of anything resembling design for performance.

A list of some of the faults - tails too big, moments too short, stability too high , longitudinal decalage too great, too much fuselage - just as a start.

They may glide from a hand launch but will not launch as you have discovered.

I second the Butterfly or one of Lee Hines Sweepettes. After mastering one of these you could try a Tony Mathews glider.

Other than the butterfly - I haven't tried these selections but they have a very good reputation.

I have been building my own 300mm span CHLG for kids whom I have been teaching over the last 5 years. 

Have fun.

John
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JB006+3/16ths
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« Reply #7 on: June 28, 2017, 03:27:17 PM »

Hello John,

In answer to the John question lots of people would stop turning their heads every five seconds to the name being uttered if there were les of them.
You're probably right about the curve competition but don't they just catch the eye.
I have a Lee Cambell Polly DT HLG kit to build at some point but have other things waiting on the list before that one.
The Polaris was an experiment to see if my building/trimming skills had improved in 8yrs and I am happy that it will glide in reasonable left hand circles on flat launch without ending in disaster - I'm not really expecting any real performance from it. Also when I've had my fill it will male a nice ornament with all those curves.
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« Reply #8 on: June 28, 2017, 07:58:54 PM »

The group of boys - the Australian Air League I work with,  are required to build a balsa glider and when I first started helping them - this vintage glider was nearly always the choice.

After almost 8 years I felt I was having a bit of success with their state body's attitude to flying models in general, when I managed to have them include a flight contest in their annual review.

For the first effort, 2 years ago a design similar to the Polaris was selected and the contest was for greatest distance in a straight line! Smiley

Our group won by concentrating on trimming our gliders with a very aft Cg, very little decalage and stability so they could be hurled hard horizontally with very little height gain and no sign of a stall.

This glider - the "Hawk" was good for this- but not for much else Smiley

Sorry about rambling on.

Have fun.
John
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RalphS
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« Reply #9 on: June 29, 2017, 09:15:49 AM »

Here's my second attempt at the Polaris, last one 8yrs ago

Just seen this  -  only 8 years ago!!!  My last Polaris was 70 years ago.  From memory, it did lovely loops.  I thought that was what it was supposed to do.

For a good modern catapult launched glider try the Hoosier Kitty.  Great model, and much easier on the muscles.
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Re: Keil Kraft Polaris
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« Reply #10 on: June 29, 2017, 01:12:58 PM »

This is the (somewhat disparate in content!) website of Mike Chapman.  He is in my local club and wins the HLG comp every year just about, I have seen his models do some remarkable flights on our little flying field at Gotham (no not the bat man one, this Gotham is pronouced "Goat-ham")  Grin

http://f4bscale.worldonline.co.uk

There is probably some useful articles and plans...

Andrew

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JB006+3/16ths
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« Reply #11 on: June 30, 2017, 04:07:34 PM »

Dear Ralph, Andrew and Hepcat,

Hepcat yes I realise all of this but just had to see, my flying pal who may be a similar age to you told me I would probably never be able to sort out the looping. Andrew  I know the F4Bscale website and made the incidence gauge that he suggests. Ralph - I'm 44 my mother wasn't even born 70yrs ago she's 70 in 2018. My first one did excellent loops but didn't hit me in the head as Hepcat reports.

John
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