Wind powered airliners

[silverslith]

bit of an interesting and probably feasible idea.

Done a fair bit of design feasibility analysis on this over the last decade.

Not much chance I could commercialise the technology in the forseeable future so happy to discuss in the public view and interest.

 

IMO these could be safer, more reliable and possibly as fast as jet Airliners.

[Cap'n Refsmmat]

How could they be as fast as a jet airliner? I've never heard of the jet stream going 600mph...

[J.C.MacSwell]

bit of an interesting and probably feasible idea.

Done a fair bit of design feasibility analysis on this over the last decade.

Not much chance I could commercialise the technology in the forseeable future so happy to discuss in the public view and interest.

 

IMO these could be safer, more reliable and possibly as fast as jet Airliners.

 

Any attempt by the plane to harness the energy of the wind will cause more drag than thrust unless it is a tailwind (in which case lift will be somewhat problematic)

[silverslith]

How could they be as fast as a jet airliner? I've never heard of the jet stream going 600mph...

 

 

Sailing at 5 to 10 times windspeed is easily achieved.

 

The key is to exploit different air layers at different velocities.

 

My theoretical design is for two flying wings with a foil cable between.

the upper one is non-loadcarrying and lighter than air. The lower one carries the cargo, winch machinery, batteries etc. The system powered flys by alternately winching in and paying out cable with efficiency in the high 90's(upper wing glides up, lower down). Sailing when different velocity air layers are available can be used to charge the batteries by using winch motors as dynamos.

VTOL is easy with this design.

The cargo/crew pod needs to rotate.

[silverslith]

Any attempt by the plane to harness the energy of the wind will cause more drag than thrust unless it is a tailwind (in which case lift will be somewhat problematic)

 

lift/drag ratios of 50:1 are routinely achieved.

[Cap'n Refsmmat]

And how would one achieve a 600mph airspeed with this? Surely the wing located in the lower-airspeed layer would impose a significant drag on the whole contraption and prevent it from reaching any significant speed.

[silverslith]

And how would one achieve a 600mph airspeed with this? Surely the wing located in the lower-airspeed layer would impose a significant drag on the whole contraption and prevent it from reaching any significant speed.

 

the wing in the lower layer serves the same anti-slippage function as the keel of a sailboat or the wheels of a landyacht, or the skates of an Iceyacht.

 

I'm an ex senior National champion in landyacht design and racing (20 years ago age 16) so I'm pretty experienced in the mechanics of sailing at 5 times windspeed with a crude cloth sail. Iceyachts achieve better.

If the upper foil is in a 200kph+ jetstream and the lower in the troposphere then I wouldn't want to postulate that supersonic sailing is impossible.

[JustStuit]

Would they be required to travel the same direction as the wind (or close to the same direction)?

[Cap'n Refsmmat]

Okay... so if I understand you correctly, the setup is similar to a kite-surfer: the upper wing pulls the lower wing along via a cable, but the lower wing is the one supporting the weight (floating in the kite-surfer example).

 

The question is, would it be feasible to do for commercial flights? You'd be limited to regions with sufficient windspeeds, speed itself would be unreliable (meaning schedules would go nuts) and you'd probably have to have a backup mechanism aboard in case the wind died, increasing complexity further.

[silverslith]

Would they be required to travel the same direction as the wind (or close to the same direction)?

 

 

no, right angles to velocity difference is ideal, apparent wind taken into consideration.

good efficiency to 10degr of up and downwind velocity dif is usual for high efficiency sailing machines.

[silverslith]

Okay... so if I understand you correctly, the setup is similar to a kite-surfer: the upper wing pulls the lower wing along via a cable, but the lower wing is the one supporting the weight (floating in the kite-surfer example).

 

The question is, would it be feasible to do for commercial flights? You'd be limited to regions with sufficient windspeeds, speed itself would be unreliable (meaning schedules would go nuts) and you'd probably have to have a backup mechanism aboard in case the wind died, increasing complexity further.

 

no the lower wing is not supporting any of the weight in the sailing scenario, actually downforce (at whatever angle) that the weight can contribute to. Its only neccesary contribution is the component of force at less than right angles to the wind experienced by the upper foil.

 

I believe with currently available satellite info on winds at different altitudes that reliable schedules could be maintained. Remember that unequalled efficiency in powered flight at 500kph+ should be feasible with this system too. Think I explained how adequately above and no extra complexity is required except software.

Even if flight time was a little unpredictable the elimination of serious ozone, greenhouse, and oceanic toxic load currently produced by jets is a biggy. Certainly even if cheap freight transportation was the first benefit then it would be very worthwhile. Remember this is likely much cheaper to build and maintain than jet airliners and the airport infrastucture is way less than stuff that lands at 200mph.

[silverslith]

below emailed from a friend. This is just momentum based exploitation of wind shear with small light RC craft. Worth noting that albatrosses fly thousands of miles non-stop by exploiting the wind shear at sealevel.

 

Are you familiar with Dynamic soaring? as used by seabirds? in the the last 5 years or so RC glider flyers have been setting speed records for RC gliders using this technique. The current world speed record being around 301MPH!!!!!!! Do a search on DSing and you should find a good explanation of how the glider guys are doing it. Essentially they are flying circuits on the leeward side of a slope, in doing so piecing a shear layer that divides turbulent wind on the lee and the prevailing wing on the windward side. If done correctly each time this shear layer is pierced the airspeed of the model is increased significantly. Check out http://www.slopeaddiction.com/thekids.html it's very impressive and fun to do.

[chilehed]

Wow! That's COOL!

 

Let's see if I get how this works. Every time the wing passes from one layer to the next there's an abrupt increase in effective airspeed, which means there's an abrupt increase in lift. Because the path of the wing is circular, the component of increased lift acting perpendicular to the plane of the wing represents an increase in the centipetal acceleration of the craft, which necessarily means that the speed with respect to the center of the path increases.

 

Am I getting it?

[J.C.MacSwell]

the wing in the lower layer serves the same anti-slippage function as the keel of a sailboat or the wheels of a landyacht, or the skates of an Iceyacht.

 

I'm an ex senior National champion in landyacht design and racing (20 years ago age 16) so I'm pretty experienced in the mechanics of sailing at 5 times windspeed with a crude cloth sail. Iceyachts achieve better.

If the upper foil is in a 200kph+ jetstream and the lower in the troposphere then I wouldn't want to postulate that supersonic sailing is impossible.

 

I'm a dinghy and iceboat racer. My first thought was that you had no energy potential to harness unless you were somehow in contact with the ground or another fluid, air or wind, at a different velocity. I just didn't realize this is what you were suggesting. You could actually go "upwind" of both "winds" using this metod, at least in theory. Interesting idea. It would be an awkward contraption though.

[bascule]

I believe Burt Rutan tried to build something like this (an airframe towed by a kite) and gave up. Not sure if it was Rutan... might've been some other experimental aircraft designer. Anyway, I think keeping the thing stable was damn near impossible.

 

I don't think the idea is feasible, and I think the OP's claims of improved safety, reliability, and speed are all hogwash. I don't think such planes would be either safe or reliable, and as far as speed goes, there's a reason why sailboats were abandoned as passenger and cargo transports: engines are faster, more reliable, and substantially easier to operate.

[Klaynos]

Two words.

 

Hang gliders.

[ecoli]

Two words.

 

Hang gliders.

 

Not the besst for mass transportation over long distances, but they do get the job done.

[chilehed]

I believe Burt Rutan tried to build something like this (an airframe towed by a kite) and gave up. Not sure if it was Rutan... might've been some other experimental aircraft designer. Anyway, I think keeping the thing stable was damn near impossible.

 

I don't think the idea is feasible, and I think the OP's claims of improved safety, reliability, and speed are all hogwash. I don't think such planes would be either safe or reliable, and as far as speed goes, there's a reason why sailboats were abandoned as passenger and cargo transports: engines are faster, more reliable, and substantially easier to operate.

I'm not sure this is the same as the Rutan idea you cite. I'm picturing two airfoils tied together and operating in airstreams of different velocities. The craft is traveling at a speed between those of the two airstreams, which means that the airfoils are oriented in different directions. Sounds crazy, but I don't see any obvious reason why it in principle couldn't work.

 

I agree that even if it works it's not likely to ever be of much commercial significance.