Doc J
Very Strong User
Hi Guys - probably time to explain how I came up with the Alpenbrise - actually a detailed design pholophy can be found here:
medium.com
Essentially; and I make no bones about this - the Alpenbrise was designed to be a real "next generation" Alpina. Anyone who has seen an orginal Alpina will love its lines, and if you have flown one then...OK I'll leave that one blank - but I dare venture to say that anyone who has seen its 2000, 3000, 4000 etc derivatives will be disappointed at how much those same lines deteriorated. Not sure about the flying qualities.
So I set out to change all that.
The idea was simply to design a good looking, fast, aerobatic and efficient 4M (157") Alpine/Slope glider as what I (and possibly I alone) conceived to be where the original Alpina SHOULD have gone. As a design aside, if it could be easily electrified then that would be a bonus. So with those short requirements in mind I set pen to paper.
Please note carefully here and now that the Alpenbrise was NOT designed to compete in any FAI racing or other class, athough it does conform - with an electric set up - to the GPS lght class. Therefore I did not design the nose to the F3f nose radius, and as to the safety aspects required on FAI models, well thats pretty funny as you'll see below.
The FAI F3f nose radius is a dubious safety feature as all of the FAI electric classes use really sharp, pointy, highly dangerous, lethal, mortally threatening, razor honed spinners - so I guess we can dispense with the hypocritical safety aspects - or is it just that the FAI electric competitiors fly more safely than the F3f bunch? No bloody idea.
The aerodynamics of the model follow the line of developments I have been making for a number of years where the high aspect ratio wing planform follows a reversed ellipse format. The wings are simply clipped at the ends, as until now I can find no lower drag or more slippery exit shape. I even tried the upright winglets so popular these days, but my conclusion was that on a slope glider they save very little fuel. And thats a comment about how useful those winglets are on anything under 6M.
The basic reversed Ellipse wing design is to try to take advantage of an elliptical lift pattern which is practical and puts the lift where its needed and nowhere else; but in doing that I also had to try to deal with the inherent problems of a truly elliptical wing - lovely though they do look. On a truly elliptical wing there is a really nasty problem - especially if its a high aspect ratio ellipse, and that is that the MAC (Mean aerodynamic chord) and the CG (Centre of gravity) ARE TOO CLOSE TOGETHER. This makes the wing far too prone to stalling as the two salient forces involved are interacting, sometimes unpedictably due to close proximity.
SEPARATING those forces helps with this problem, and you can continue with this philosphy by lowering the aspect ratio until the MAC and the CG separate really far, which can eliminate the conventional stall altogether. This is what you sometimes see on a low aspect ratio delta - there is no actual stall - just a mushy descent.
So Alpenbrise is not an FAI model and was never designed to be one, so if it doesn't conform to FAI regulations in any way - other than weight of course - then thats not unduly surprising. It does have curvy lines so was never suitable for (Heaven forbid) a slip on nosecone, its a high end sport model that can be used for light class GPS with the addition of an electric motor setup - and a sharp spinner
- and a whole bunch of associated electornics.
I hope the build quality is improving because I'm sure as hell trying to get it better, and have been for many years.
Alpenbrise is what it is: A high end 4M Slope or Alpine sport model - that can be electrified (if you want to risk those razor-sharp spinners
) and used for FAI GPS Light cass. Period.
The model has been reviewed in the European mags very favourably by some very picky pilots, with the testers commenting esecially on the model's durability, lack of wing flexing, speed and aerobatics capabiity - plus the lack of any kind of bad behaviour even when induced. There are now over 40 flying in Europe and 28 more on order which must say something for the design as its only been out for a year or so.
I'm happy to answer any sensible questions by the way.
Cheers,
Doc.
Designing for an Alpine Soarer
The hills are alive…with sailplanes designed for for the rigours of mountain soaring.
Essentially; and I make no bones about this - the Alpenbrise was designed to be a real "next generation" Alpina. Anyone who has seen an orginal Alpina will love its lines, and if you have flown one then...OK I'll leave that one blank - but I dare venture to say that anyone who has seen its 2000, 3000, 4000 etc derivatives will be disappointed at how much those same lines deteriorated. Not sure about the flying qualities.
So I set out to change all that.
The idea was simply to design a good looking, fast, aerobatic and efficient 4M (157") Alpine/Slope glider as what I (and possibly I alone) conceived to be where the original Alpina SHOULD have gone. As a design aside, if it could be easily electrified then that would be a bonus. So with those short requirements in mind I set pen to paper.
Please note carefully here and now that the Alpenbrise was NOT designed to compete in any FAI racing or other class, athough it does conform - with an electric set up - to the GPS lght class. Therefore I did not design the nose to the F3f nose radius, and as to the safety aspects required on FAI models, well thats pretty funny as you'll see below.
The FAI F3f nose radius is a dubious safety feature as all of the FAI electric classes use really sharp, pointy, highly dangerous, lethal, mortally threatening, razor honed spinners - so I guess we can dispense with the hypocritical safety aspects - or is it just that the FAI electric competitiors fly more safely than the F3f bunch? No bloody idea.
The aerodynamics of the model follow the line of developments I have been making for a number of years where the high aspect ratio wing planform follows a reversed ellipse format. The wings are simply clipped at the ends, as until now I can find no lower drag or more slippery exit shape. I even tried the upright winglets so popular these days, but my conclusion was that on a slope glider they save very little fuel. And thats a comment about how useful those winglets are on anything under 6M.
The basic reversed Ellipse wing design is to try to take advantage of an elliptical lift pattern which is practical and puts the lift where its needed and nowhere else; but in doing that I also had to try to deal with the inherent problems of a truly elliptical wing - lovely though they do look. On a truly elliptical wing there is a really nasty problem - especially if its a high aspect ratio ellipse, and that is that the MAC (Mean aerodynamic chord) and the CG (Centre of gravity) ARE TOO CLOSE TOGETHER. This makes the wing far too prone to stalling as the two salient forces involved are interacting, sometimes unpedictably due to close proximity.
SEPARATING those forces helps with this problem, and you can continue with this philosphy by lowering the aspect ratio until the MAC and the CG separate really far, which can eliminate the conventional stall altogether. This is what you sometimes see on a low aspect ratio delta - there is no actual stall - just a mushy descent.
So Alpenbrise is not an FAI model and was never designed to be one, so if it doesn't conform to FAI regulations in any way - other than weight of course - then thats not unduly surprising. It does have curvy lines so was never suitable for (Heaven forbid) a slip on nosecone, its a high end sport model that can be used for light class GPS with the addition of an electric motor setup - and a sharp spinner
- and a whole bunch of associated electornics.I hope the build quality is improving because I'm sure as hell trying to get it better, and have been for many years.
Alpenbrise is what it is: A high end 4M Slope or Alpine sport model - that can be electrified (if you want to risk those razor-sharp spinners
) and used for FAI GPS Light cass. Period.The model has been reviewed in the European mags very favourably by some very picky pilots, with the testers commenting esecially on the model's durability, lack of wing flexing, speed and aerobatics capabiity - plus the lack of any kind of bad behaviour even when induced. There are now over 40 flying in Europe and 28 more on order which must say something for the design as its only been out for a year or so.
I'm happy to answer any sensible questions by the way.
Cheers,
Doc.
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