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Old Feb 06, 2015, 12:52 PM
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Quote:
Originally Posted by Marko Gala View Post

When I kept thinking about its miracle flying weight I realised it is just a bubble which has already splashed. Flying weight is just an illusion. What is really important is wing loading.
It lacks wing area (only 60 sq.dm). For instance: Kappa at 1270 grams has exactly the same wing loading as Perfection or Stork at 1570 grams. The myth of Kappa being the lightest F5J model is busted. Now we have F5J models at the same weight of Kappa but with 14 or 17 additional sq.dm of wing area.

One thing to consider is that in terms of wing loading the Kappa may not be the "lightest" but this is due to the planes high aspect ratio wing. These sorts of wings give the planes legs to range further than the pack. All of these planes are going to thermal well, the question now becomes who can go the furthest and still make it back. There was a similar discussion when the Egida first came out, that plane has since proven itself time and time again.

The plane, as Bohus (our wonderful manufacturer) has mentioned is only 11 months old, our prediction is over the course of the next few years we will see some serious wins with this model. Stay tuned!
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Old Feb 07, 2015, 08:18 AM
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Hmm ... I am curious why the sudden 'hate post' by a Euro pilot that competes and flys a different brand.

Still, I am going to buy one; not because I compete ( I don't ) but because it is cool looking, it is red and I can make that wing loading fly.
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Old Feb 07, 2015, 11:30 AM
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Quote:
Originally Posted by Marko Gala View Post
Does anybody know if the ballast is being prepared for Kappa? I can not imagine 1250 gram plane being full competitive... maybe that´s one of the answers why Kappa has not had any significant success at any big intl. F5J contest in Europe so far.

When I kept thinking about its miracle flying weight I realised it is just a bubble which has already splashed. Flying weight is just an illusion. What is really important is wing loading.
It lacks wing area (only 60 sq.dm). For instance: Kappa at 1270 grams has exactly the same wing loading as Perfection or Stork at 1570 grams. The myth of Kappa being the lightest F5J model is busted. Now we have F5J models at the same weight of Kappa but with 14 or 17 additional sq.dm of wing area.

12 g/sq.dm FAI limit is soon to be reached in F5J. But this piece is not gonna make it.

Happy landings
Marko
Wing loading doesn't mean that much. Span loading is the important factor for minimum sink rate. The Kappa has about a 363g/m span loading, and a Stork 6E even at 1570g (1700g+ seems to be more typical from what I can find) and 3.82m span has about a 411g/m span loading. The Kappa's is about 13% less, which should mean the minimum sink rate is improved, but of course Re and airfoil affects also come into play.

Aspect ratio is the important factor for best L/D. The Kappa has approx. AR = 20.3. I believe the Stork 6 wing area is 74.64dm^2, which would give an AR = 19.6? That is pretty close to the same, and off course Re and airfoil affects again mean that higher AR does not necessarily directly translate to higher L/D.

They are both probably excellent F5J gliders. To focus only on wing loading doesn't really tell anyone which might be the better glider, even if a 1570g Stork 6 was available to everyone.

Kevin
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Old Feb 08, 2015, 01:19 PM
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Thank you!! I WAS going to say the same thing but didn't feel I was qualified to do so.
The Kappa is DEFINITELY on my short list of F5J sailplanes I'd like to have.
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Old Mar 28, 2015, 03:26 PM
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I got a Kappa finished up recently. I got a few flights on it last weekend, and some more today. It's a fine flying model!

I built mine light so it only weighs 42 ounces. Floats really well on any lift at all, and still moves up wind with authority with a bit of reflex dialed in.
It does get tossed around quite a bit in the (10mph) wind though.

I'm using the Neu 707 motor and I couldn't ask for better performance. Climb rate is right at 10M/sec, so 15 seconds to 150M.

Lenny
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Old Mar 28, 2015, 04:34 PM
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Lenny ... what version of the Kappa did you get? Do you consider the wing and skin thickness to be 'durable' or can it be easily penetrated by fingers and sticks?

thanks
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Old Mar 28, 2015, 10:28 PM
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Lou,

It's the light version. No, I don't feel like there any danger of penetrating the wing skin with a finger.
It seems to be about as durable as other glass skinned models, like a Supra.

I think a stick probably would go through the skin if you landed on it.

Seems plenty strong for it's intended use in the air. I have flown gentle loops and rolls with it just to see how it handled it and there was no problems.

Lenny
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Old Mar 28, 2015, 10:51 PM
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Many thanks Lenny. I have been reading of issues with some of the very light weight F5J planes with increased susceptibility to damage. Good to know the Kappa 35 is sturdy. I am toying with the D-box version, it is middle of the road and in my price range.

Who did you buy from and how long was the wait for the plane? Did it arrive well packed and undamaged?

Lou
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Old Mar 29, 2015, 01:50 PM
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I got it from Skipmiller models and I think the wait was only a few months.
Since they are local, I just picked it up in person.

Lenny
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Old Apr 03, 2015, 05:31 PM
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Quote:
Originally Posted by kcaldwel View Post
Wing loading doesn't mean that much. Span loading is the important factor for minimum sink rate. The Kappa has about a 363g/m span loading, and a Stork 6E even at 1570g (1700g+ seems to be more typical from what I can find) and 3.82m span has about a 411g/m span loading. The Kappa's is about 13% less, which should mean the minimum sink rate is improved, but of course Re and airfoil affects also come into play.

Aspect ratio is the important factor for best L/D. The Kappa has approx. AR = 20.3. I believe the Stork 6 wing area is 74.64dm^2, which would give an AR = 19.6? That is pretty close to the same, and off course Re and airfoil affects again mean that higher AR does not necessarily directly translate to higher L/D.

They are both probably excellent F5J gliders. To focus only on wing loading doesn't really tell anyone which might be the better glider, even if a 1570g Stork 6 was available to everyone.

Kevin
I think wing loading is often brought up because it is easy to calculate and often provided by the suppliers. It is also what we manipulate with ballast.

Span loading and AR are not typically provided so it becomes a little more difficult to compare. Nor do I have a good understanding of what good and lesser numbers might be.

It would be interesting to see the AR and span loading of some of the "top" ships to get a feel for the range. then compare them to the midrange ships and see what that tells us.

These are not specs that I have been used to using or calculating so I have no basis of comparison. But I would be interested to learn.

Today I look at airfoil, overall weight and wing loading to get a first cut impression of the characteristics of a glider. More info and more indicative information would be good to know.
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