German Student team build Human Powered Aircraft hoping to break the world record for longest flight.

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alyxms@reddit

I went down the rabbit hole on human powered helicopter a few years ago. For some reason I didn't look into fixed wing flight.

Bet the record is way longer(last time I looked, the record for heli was like a minute), since you need way less power to maintain flight.

I imagine they can extend whatever record they do manage to achieve by hiring a tour de france cyclist as the pilot.

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stedews@reddit

Didn't a fixed wing cross the English Channel from England to France?

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punkfunkymonkey@reddit

Someone did Crete to (nearly) Santorini in 1988, 70+ miles

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Longest flight, I believe, is Daedalus, an MIT project that flew 71 miles from Crete to the Greek island of Santorini in 1988. I had a chance to see them testing a prototype, the Michelob Light Eagle at Hanscom airport near Boston. The aircraft is now hanging at Dulles Airport.

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pi_stuff@reddit

hiring a tour de france cyclist

This. Speaking from experience, it's a lot easier to learn to fly than to train to achieve the power-to-weight ratio of an elite cyclist.

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JJohnston015@reddit

They've done just that. Look into Paul MacCready, Bryan Allen and the Gossamer Condor and Gossamer Albatross.

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alyxms@reddit

Nice.

One of the human powered helis I looked at had the pilot cycling with both of their arms and legs to get the power needed.

So I thought, if the limit is on the human, get better humans.

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Cormelio@reddit

I mean I see no reason this should fly a shorter amount of time than a glider so 14h should be fine

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Aditya1311@reddit

True, it's massively easier once in the air. However the main limiting factor is heat: the pilot/engine compartment is very poorly ventilated as windows add unacceptable drag. Even a top Tour de France competitor would be affected by heat exhaustion long before their muscles gave out

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Thermodynamicist@reddit

The problem with these machines is that they are really ground effect vehicles. Getting a human powered vehicle off the ground at all is very impressive, but I don't think I've ever seen one climb out of ground effect on a still day.

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armagin@reddit

I dunno man, I'm pretty sure with this crazy aspect ratio you'd need to be sooooo close to the ground for ground effect to have a meaningful impact on performance.

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GlockAF@reddit

High aspect ratio makes is easier to utilize ground effect, not harder

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HardlyAnyGravitas@reddit

Larger wing span reduces drag.

Longer chord increases lift in ground effect.

The aspect ratio doesn't (directly) have anything to do with it - the chord length vs the height above ground does.

Increasing the aspect ratio (by making the wing longer) while maintaining the same chord length will reduce drag.

Decreasing the aspect ratio (by making the chord longer) while maintaining the same wing span will increase lift in ground effect.

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Jessie_C_2646@reddit

In some cases it's easier to keep flying than to land. The U-2 comes to mind, which has to be stalled at just the right moment over the runway or it'll keep on flying forever.

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Thermodynamicist@reddit

AFAIK:

Ground effect is a function of how many spans the vehicle is above the ground rather than the absolute distance.
Drag due to lift is a function of span loading, not aspect ratio.

Drag due to lift = L^2 / (q * π * b^2 )

(add span efficiency to taste)

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wildskipper@reddit

That's still flying though, isn't it? An albatross uses ground effect, for example, but I'm sure we'd still describe it as flying.

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Thermodynamicist@reddit

Perhaps, but we draw a distinction between ground effect vehicles and conventional aeroplanes. The safety case for most human powered aircraft is not to climb higher than you're prepared to fall, which allows the structure to be lighter.

Of course, as others have pointed out, once out of ground effect, these aeroplanes would be good gliders, and so we would simply exchange one grey area for another.

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mz_groups@reddit

I assume they will be adding a fairing for the pilot eventually?

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Hot_Winner_8162@reddit (OP)

Yeah for aerodynamic reasons the world record plane will have a proper cockpit. But for testing it is better to fly without. The fairing is one use so it would be destroyed.

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d_andy089@reddit

Huh. Interesting. Makes you wonder how much change this would take to make it an electric one...

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Hot_Winner_8162@reddit (OP)

Actually not that much.

DLR (German Aerospace Center) is building a very similar Aircraft powered by solar panels.

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michal_hanu_la@reddit

I wonder how does the record work --- are thermals allowed? Because this thing looks like it would be a decent glider and those can stay up all day.

(Of course the launch gets quite a bit harder when one has pedals instead of a tow plane...)

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