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Sraight'nlevel

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There may well be... but I think that may be more about the availablity of the airplanes than the number of people who could do it. As noted, the entire peloton of the TdF could fly human powered planes quite well. Horsepower wise.

About chain, not in comparison to kevlar thread there isn't.

I bet there would be a business in having a field where people could sprint little planes up to speed and get useful hops.
Kevlar has to be pretty robust to survive.

Titanium is only 0,27 kg.

 
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Sraight'nlevel

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The thought occurs; Would HPA records be better attempted in the middle of Death Valley in the early Spring to gain advantage of reverse altitude density, and cooler temperatures for the 'engine'?
I bet...only reason they fly over water is safety...less broken bones when the structure fails.

I figure they fly anything that holds together....and they cannot afford to test the structure. They fly in just 10-15 ft.
 

Sraight'nlevel

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How to make a toast using human power ;)

I am more interested how to get messages into the toast...like the picture of Jesus Christ ?!

Well...everything that we know is very limited...as this test shows us...one thing is for sure...you need a sizeable prop:

 
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Sraight'nlevel

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I just discovered that bigger is better...increasing the Re from 100 000 to 2 000 000 at speed of M 0.04 of gave me a wing profile L/D increase from 54 to113.

Thicker batch is re 1 to 2 million and the looser group is re 100 thousand to 300 thousand.

How come no one is using this data in HPAs..it is common knowledge anyhow.
 

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ARP

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When Bryan Allen was pedaling across the Channel, the support crews had boats on the water to pick him up should he lose his ability to power the plane. He was flying at ~30' above the water, calculated to be optimum. As he got around 2/3 across, his energy level decreased and he began to gradually lose altitude. The rescue teams were right under him, ready to grab the plane and get him out. But he found that when he got about 5' above the water, the pedaling got easier because of ground effect and he was able to complete the flight.

The team got help from unexpected sources. The Channel has very busy shipping traffic. As he was half-way thru the flight, spotters for ship traffic saw an oil tanker coming along and figured it would intersect the flight. They somehow managed to contact the ship's Captain and he graciously slowed the ship down so Albatross could pass without wake-turbulence damaging the plane. The success of the project was full of lucky circumstances.
In the book 'Gossamer Odyssey' it says " At 06:26 Allen signaled that he wanted a tow. When he climbed higher to clear the rescue boat he found smoother air and decided to go on." So the ground effect did not make pedaling easier!
 

Sraight'nlevel

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How come no one is using tjshis data in HPAs..it is common knowledge anyhow.
In the book 'Gossamer Odyssey' it says " At 06:26 Allen signaled that he wanted a tow. When he climbed higher to clear the rescue boat he found smoother air and decided to go on." So the ground effect did not make pedaling easier!
That is correct but he was still in ground effect at 15 ft. I bet the air at sea level was more turbulent...uneven.

At 45:45:
 

Sraight'nlevel

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-iff seriouse,today/tomorrow it is possible to made
superenergyefficient thrusters
(oscillating with specidic thrust circa 200 kG/HP)

and passive wings(body) with allmost NEGATIVE drag (semithrusters !)
How do you make them oscillate ?
 

Brünner

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I agree just.... I am not sure what "better" design means 🤔
Longer wings? Higher aspect ratio? Oscilating wings?

In my personal opinion.... I prefer to use actually available materials and technologies. And basic weight saving rule = keep it as simple as possible ;)
More power. The human body is simply too weak for the task, so it needs to be enhanced.
Artificial muscles might help in this aspect.

 

Aesquire

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Rochester, NY, USA
The turbulence & wind is very different close to the ground. Magnitude and repercussions.

Assuming flat ground, with no trees, buildings, etc. for hundreds or preferably thousands of yards/meters, you get higher, smoother, wind speed as you go up, but not in a smooth curve. There's a definite change from relatively laminar flow to slower turbulent flow. (and often a small ground level stillness that can usually be ignored on Human scale flying machines, but vital with insects and "palm of the hand" & smaller models/drones )

That transition zone ( as the Gossamer Albatross story above shows ) can be well above ground effect for a smaller craft. The Gossamer series with 100 foot spans is a very unusual example. A typical hang glider with a mere 40 foot span ( or Cessna ) might pass into the wind gradient long before it gets the ground effect "bonus".

The various gradient effects are well worth a thread of their own, being partly responsible for the "downwind turn myth" and a good incentive to perform landing approaches with plenty of energy, instead of stabilizing just above stall and risking "the bottom falling out" effect as pass through the gradient.
 

Sraight'nlevel

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ARP

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How come no one is using tjshis data in HPAs..it is common knowledge anyhow.

That is correct but he was still in ground effect at 15 ft. I bet the air at sea level was more turbulent...uneven.

At 45:45:

Yes the turbulence was worse close to the sea but ground effect reduces with height so less of a bonus.
 

goney3

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I just discovered that bigger is better...increasing the Re from 100 000 to 2 000 000 at speed of M 0.04 of gave me a wing profile L/D increase from 54 to113.

Thicker batch is re 1 to 2 million and the looser group is re 100 thousand to 300 thousand.

How come no one is using this data in HPAs..it is common knowledge anyhow.
Two things:

1) Download the latest XFLR5: XFLR5 - Browse Files at SourceForge.net

2) An airfoil is not the same as a 3D shape, please use the plane editor when trying to look at your L/D. You can also use the NASA tool OpenVSP (which is FREE) to get much better L/D calculations instead of an infinite span airfoil cross section ;)

I would also be mindful of the amount of drag that is created if your large propeller were to (for any reason) stop spinning. 👍
 

Sraight'nlevel

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Messages
371
Two things:

1) Download the latest XFLR5: XFLR5 - Browse Files at SourceForge.net

2) An airfoil is not the same as a 3D shape, please use the plane editor when trying to look at your L/D. You can also use the NASA tool OpenVSP (which is FREE) to get much better L/D calculations instead of an infinite span airfoil cross section ;)

I would also be mindful of the amount of drag that is created if your large propeller were to (for any reason) stop spinning. 👍
I have the latest XFLR-5 thank you. I am talking about so called form lift vs form drag. Like in Wortmann FX 63-137 they have L/D 137 at 2,5 AOA @ 1 mio Re.

Anyhow...what I discovered is is that when you put a man like me flying the HPA ( 260 LBS ) you need to make craft at least an 70-80 pounder.

This way you start to create some believable speeds like 15 m/s...it is a huge difference in lift between 12 and 15 m/s.

Also you can design the entire aircraft make lift ( using the knowledge by DeMonge and Burnelli ). Kinda like a recumbent. This way the entire drag of the "man-box" disappears as it will be part of the lift equation.

Prop being 2.8 m is enough.



Having the wing area like in Musculair 2 is not enough, but lifting fuselage derivation will add amble of lift in ground effect.

I would also take the measures from the prehistoric bird above for span vs length ( 5:1 ).

Main idea is increasing lift area thus diminshing the induced drag....parasitic drag does not increase.

------

I tried to beat the Wortmann foil with mine but "only" got L/D 142 at @ 1 mio Re.

Looks like the Lissaman 77xx(ish) is very efficient.
 
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