Need some education here, I have a Nash 1650 and 2000 front wing aspect ratio 4.8 and 5 respectively.
which one allows me to have a higher terminal velocity given everything is the same ie. wind strength, wing area etc.
Many thanks
Drag and resistance can occur from overall wing size and the size of the leading edge. The flatter the profile ie high aspect compared to a low aspect wig, the greater the speed.i would think your 1650 is going to be faster overall.
Drag is primarily made up of two component, parasitic drag and induced drag. Parasitic drag is proportional to the area of the wing and the square of the velocity. Foil section and angle of attack are also factors, but for the sake of argument you can assume these are constants.
induced drag is dependent the aspect ratio and the lift coefficient, which itself is dependent on the angle of attack, which in turn will be determined by the area of the wing and the square of the velocity.
So as speed increases, parasitic drag increases and induced drag decreases, as in the diagram below
The net result is that at low speeds, total drag is dominated by induced drag, and at high speed, drag is dominated by wing area. As a general rule, for straight line performance you should aim to maximise wing span to minimise induced drag, then choose wing area based on the speed range you wish to operate in, large area wings for low speed efficiency, narrow chord wings for high speed flight.
Select to expand quotePacey said..
Drag is primarily made up of two component, parasitic drag and induced drag. Parasitic drag is proportional to the area of the wing and the square of the velocity. Foil section and angle of attack are also factors, but for the sake of argument you can assume these are constants.
induced drag is dependent on the square of the velocity, the aspect ratio and the lift coefficient, which itself is dependent on the angle of attack, which will be determined by the area of the wing.
so the net result is that at low speeds, total drag is dominated by induced drag, and at high speed, drag is dominated by wing area.as a general rule, for straight line performance you should aim to maximise wing span to minimise induced drag, then choose wing area based on the speed range you wish to operate in, large area wings for low speed efficiency, narrow chord wings for high speed flight.
Just what I was thinking.
Well sort of, skinny wings go fast.
And for anyone that doubts the benefits of wingspan, this is where glider design gets to when wingspan is not constrained.
Note that gliders require both low speed performance for optimal climb in thermals, then high speed performance for travelling between thermals as efficiently as possible. So even with the low speed requirement, the wings still tend towards high aspect ratio
Similarly, this is a state of the art International Moth foil, and I think it shows that SUP/Windfoil/Wingfoil foils can still potentially go to higher aspect ratios for outright performance. However downsides might include loss of manoeuvrability and pitch stability, and while in some cases these can be reduced by other design factors such as anhedral, sweep, fuselage length and stabiliser area, high aspect ratio is not going to be ideal for everyone.
Select to expand quotePacey said..
And for anyone that doubts the benefits of wingspan, this is where glider design gets to when wingspan is not constrained.
Note that gliders require both low speed performance for optimal climb in thermals, then high speed performance for travelling between thermals as efficiently as possible. So even with the low speed requirement, the wings still tend towards high aspect ratio
Similarly, this is a state of the art International Moth foil, and I think it shows that SUP/Windfoil/Wingfoil foils can still potentially go to higher aspect ratios for outright performance. However downsides might include loss of manoeuvrability and pitch stability, and while in some cases these can be reduced by other design factors such as anhedral, sweep, fuselage length and stabiliser area, high aspect ratio is not going to be ideal for everyone.
What is the size of the Moth wing?
Select to expand quotebigtone667 said..Pacey said..
And for anyone that doubts the benefits of wingspan, this is where glider design gets to when wingspan is not constrained.
Note that gliders require both low speed performance for optimal climb in thermals, then high speed performance for travelling between thermals as efficiently as possible. So even with the low speed requirement, the wings still tend towards high aspect ratio
Similarly, this is a state of the art International Moth foil, and I think it shows that SUP/Windfoil/Wingfoil foils can still potentially go to higher aspect ratios for outright performance. However downsides might include loss of manoeuvrability and pitch stability, and while in some cases these can be reduced by other design factors such as anhedral, sweep, fuselage length and stabiliser area, high aspect ratio is not going to be ideal for everyone.
What is the size of the Moth wing?
Don't know, haven't been able to find any specs for it. Website is www.blueworksfoiling.com/technical, price is scary 2290 Euro, and I think that is just for the wing, no vertical strut.
It looks like it could be adapted to a custom fuselage for SUP foiling or wind foiling etc, with the additional benefit that it can have it's camber adjusted via the hinged flap at the back - more camber and higher lift for light conditions, less camber for high speeds. But someone else with deeper pockets can take on that project
Went through the same process with hang gliders years ago ......higher aspect / thinner profile faster wings with better glide ,but the compromise was not as easy to turn and twitcher to fly.
So we ended up with 3 basic types
1.training glider ( low aspect easy turning low stall speed )
2. intermediate glider ( mid aspect faster/ better glide/ still good turning )
3. Advanced glider ( High aspect fast/ great glide/ crap handling)
Can see the same pattern happening with foil wings.
Love my mid aspect HS1550. Great compromise. Most people will end up on mid aspect foils.
Yep , I agree, with flying HA you trade a lot of handling and safety for a little bit of performance, and I suspect with foiling it will be the same.
Select to expand quotePacey said..
And for anyone that doubts the benefits of wingspan, this is where glider design gets to when wingspan is not constrained.
Note that gliders require both low speed performance for optimal climb in thermals, then high speed performance for travelling between thermals as efficiently as possible. So even with the low speed requirement, the wings still tend towards high aspect ratio
Similarly, this is a state of the art International Moth foil, and I think it shows that SUP/Windfoil/Wingfoil foils can still potentially go to higher aspect ratios for outright performance.
How about 1.4 metre span, AR of around 14
Select to expand quotecontainer said.How about 1.4 metre span, AR of around 14
Love the fact that you're giving it a go. Reckon straight line glide will be awesome. Please post again with a ride report.
Is it based on a Horten wing?
Does that also mean tail less?
Select to expand quoteStingersup said..container said.How about 1.4 metre span, AR of around 14
Love the fact that you're giving it a go. Reckon straight line glide will be awesome. Please post again with a ride report.
Is it based on a Horten wing?
Does that also mean tail less?
Very cool, what foil section did you use?
Looks great Container! Did you shape it by hand or luck enough to know someone with a CNC machine? I'm shaping a 1.2m HA by hand out of Paulownia around 8.5 AR. Tricky with a tube mount compared with the Axis system but you get to keep the thickness down.
Cheers bois, it is designed on paper and shaped by hand, 80kg m/3 pvc foam. not directly based on a horten wing but it does use the same lift distribution concept, It looks similar as the axis mount constrains the size of the wing root so you end up with that big spikey bulge out the back.
I can neither confirm nor deny the existence of a tail wing
Relapse- you have to show us now! a square tube gofoil style mount should be exactly the same to build, the only extra step would be pre forming the tube
Select to expand quote
Very cool, what foil section did you use?
I used the ratios of an eppler 195, 12% thick but the actual shape is modified slightly as it changes along the span
I kept the plan form simple to make getting the foil right easier. 3D printed the tip foils and glued then in place and printed a center template in two halves. Rough shaped with an electric planer then hand plane and finally an ordeal sander. Wood is quite stiff but still needs a layer of carbon for stiffness
Nice shape!
you could try leaving the bottom half of the foil unshaped to begin with. This provides a flat, true surface to keep it still and level while you shape and laminate the top and set the socket. It will also hold the core steady against resin shrinkage while it cure. I do this with my wings and it works a treat
The X 14/11. 14 is AR and 11 (deg.) is total amount of twist from root to tip. I know i know it looks ridiculous but its only a flat water test bed for mk. Deux
And get this- the wing is dead flat (if you chop it through 1/4 chord) but it is also technically anhedral on the leading edge but dihedral on the trailing edge
Select to expand quotecontainer said..
Looks awesome. So are you going for a Prantl lift distribution? Are you also reducing the camber of the wing profile as it moves towards the tips?
Very interested in hearing how this goes, might be brilliant, might be a disaster
Awesome! Was very keen to see if the Prandtl-D wing concept, now I don't have to 
, let us know how it goes, I reckon tail less wings will be the go for surf and wing foiling
Select to expand quotePacey said..
Looks awesome. So are you going for a Prantl lift distribution? Are you also reducing the camber of the wing profile as it moves towards the tips?
Very interested in hearing how this goes, might be brilliant, might be a disaster
Cheers. Yeah agree with you there, either gonna be awesome or an expensive lesson. i spoke to al bowers, the nasa scientist who ran the study on the prandtl flying wing, he gave me a couple of numbers to use regarding wing twist and where exactly to put it.
I used a slightly cambered section (eppler195) out to where the lift becomes zero, then it changes to symmetrical to the tip. You can use either a highly camber or completely symmetrical foil out here, im wanting to maximise downforce so went with the latter. I would say the former will be more efficient on paper. The centre just is what it is to fit the axis mount in
My thinking here is the +9 degrees aoi in the centre will provide the lifting force necessary to keep foot position roughly the same, -2 degrees at the tips will provide downforce and positive pitching moment.
Now imagine if you will a yellow fin tuna or marlin tail laid flat, mast in the crux of tail and tips swept back 31 degrees so they are behind the mast and thus producing downforce behind your back foot position.... why was it you needed a tail wing again? 
Select to expand quotecontainer said..Pacey said..
Looks awesome. So are you going for a Prantl lift distribution? Are you also reducing the camber of the wing profile as it moves towards the tips?
Very interested in hearing how this goes, might be brilliant, might be a disaster
Cheers. Yeah agree with you there, either gonna be awesome or an expensive lesson. i spoke to al bowers, the nasa scientist who ran the study on the prandtl flying wing, he gave me a couple of numbers to use regarding wing twist and where exactly to put it.
I used a slightly cambered section (eppler195) out to where the lift becomes zero, then it changes to symmetrical to the tip. You can use either a highly camber or completely symmetrical foil out here, im wanting to maximise downforce so went with the latter. I would say the former will be more efficient on paper. The centre just is what it is to fit the axis mount in
My thinking here is the +9 degrees aoi in the centre will provide the lifting force necessary to keep foot position roughly the same, -2 degrees at the tips will provide downforce and positive pitching moment.
Now imagine if you will a yellow fin tuna or marlin tail laid flat, mast in the crux of tail and tips swept back 31 degrees so they are behind the mast and thus producing downforce behind your back foot position.... why was it you needed a tail wing again?
There is a key difference between using a symmetrical versus cambered foil at the tips, and that is that using the symmetrical section will introduce roughly 2- 3 degrees of additional twist over a typical cambered section. This is aerodynamic twist though, rather than geometric twist.
If this sounds counter-intuitive, think of it this way. A symmetrical section produced zero lift at zero AoA, whereas a cambered section produces positive lift at zero AoA. So to get a cambered section to produce zero lift, you have to pitch it nose down by a few degrees, say 3 for purposes of illustration. So if you have a cambered section at the tip twisted off to -5 degrees, it's equivalent to a symmetrical section twisted of to -2 degrees.
I agree entirely about sweep with this wing configuration, the next step would be to sweep it significantly and remove the stabiliser, although you may need a small amount of reflex at the root to compensate for the pitching moment of the cambered section there
Select to expand quotecontainer said..
Now imagine if you will a yellow fin tuna or marlin tail laid flat, mast in the crux of tail and tips swept back 31 degrees so they are behind the mast and thus producing downforce behind your back foot position.... why was it you needed a tail wing again?
A planform something like a Horten wing?
Had a chance to test it yet Container? I should get a chance to try mine tomorrow, just needs a trim and hot coat today.
Residing in Maui I see a lot people on all kinds of gear. Wingfoiling is Blowing Up! GoFoil appears to be most popular, followed closely by by Naish, Axis and Armstrong. I'm 165# / 76kg ...I switched to Armstrong 1550 /1200 from Axis, now I'm having fomo that Armstrong does not have a true HA foil. The guys on GoFoils GL 140 are on a relatively small wing and just blazing, early planing, better glide and excellent maneuverability . Am I missing something here? They are on 1000-1150 cm wing and I'm on a 1550 ... but they have far more efficiency? Is this my imagination and fomo or is it real? I've got foil brain...Someone in the know I was speaking with stated the whole industry will be going high aspect in due time...of course that's just an opinion... I was thinking of getting a GoFoil or Axis (Execellent Selection of foils) , but still keeping my Armstrong maybe dumping the 1550 and 1200 before they release their HA wings as I heard they will have some HA wings "someday" but it's nowhere soon it seems.. Thoughts? Comments?
Select to expand quotebluewave said..
Residing in Maui I see a lot people on all kinds of gear. Wingfoiling is Blowing Up! GoFoil appears to be most popular, followed closely by by Naish, Axis and Armstrong. I'm 165# / 76kg ...I switched to Armstrong 1550 /1200 from Axis, now I'm having fomo that Armstrong does not have a true HA foil. The guys on GoFoils GL 140 are on a relatively small wing and just blazing, early planing, better glide and excellent maneuverability . Am I missing something here? They are on 1000-1150 cm wing and I'm on a 1550 ... but they have far more efficiency? Is this my imagination and fomo or is it real? I've got foil brain...Someone in the know I was speaking with stated the whole industry will be going high aspect in due time...of course that's just an opinion... I was thinking of getting a GoFoil or Axis (Execellent Selection of foils) , but still keeping my Armstrong maybe dumping the 1550 and 1200 before they release their HA wings as I heard they will have some HA wings "someday" but it's nowhere soon it seems.. Thoughts? Comments?
I think there is a general misunderstanding of the effects of aspect ratio. For a given wing area, a high aspect ratio foil will have similar parasitic drag and lower induced drag, so it will be more efficient. However for two foils with the same aspect ratio, but different wingspans and areas, the one with the larger span will be better.
Basically the key variable in the drag equation is span, and for two foils of the same span you can increase or decrease the chord and therefore area quite a bit and still have similar overall drag characteristics.
It's the reason that gliders have gone for ever increasing span over the past 50 years to maximise lift/drag ratios, despite the structural issues and the increased difficulties in handling on the ground. Glider pilots even have an acronym for it:
