jackmac
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human-powered aircraft

Wed Nov 13, 2019 9:07 am

My dream is to one day create self powered flying machine. If i wanted to learn everything that you would need to create a human-powered aircraft. What areas would you recommend studying? like an example curriculum.
 
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flyingturtle
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Re: human-powered aircraft

Wed Nov 13, 2019 10:35 am

I'd recommend studying the history of the first human-powered aircraft - as a hobby, to prepare the further work. And more seriously: Get into an engineering field, primarily a field that researches light-weight materials.

Wookiepedia says: "Human-powered aircraft have been successfully flown over considerable distances. However, they are still primarily constructed as engineering challenges rather than for any kind of recreational or utilitarian purpose."

Human-powered aircraft are still not built by aviators or aviation engineers, but often by people in materials science.
Reading accident reports is what calms me down
 
prebennorholm
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Re: human-powered aircraft

Thu Nov 14, 2019 2:24 am

jackmac wrote:
My dream is to one day create self powered flying machine. If i wanted to learn everything that you would need to create a human-powered aircraft. What areas would you recommend studying? like an example curriculum.

That train left forty years ago. Have a look at https://en.wikipedia.org/wiki/MacCready ... _Albatross

There are no later invention which significantly changes that.

Some numbers: With optimal aerodynamics (like the Gossamer Albatross) you need 1.3W power to keep one lb off the ground. Assuming your body weight = 150 lb, and a plane empty weight = zero, then you need 150 x 1.3 = 200W power.

Continuous muscle power of an ordinary man varies. Bad shape = 50W. Really good and well trained shape = 150W. A Tour de France winner can do 400W for the duration of one hour.

Now build the plane as lightweight as you can, and add its empty weight to your body weight to get the gross weight, and redo the calculation.

Better make a pedal powered helium balloon.
Always keep your number of landings equal to your number of take-offs
 
jackmac
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Re: human-powered aircraft

Thu Nov 14, 2019 5:51 am

Appreciate the responses guys! Im definitaly going to look into the Albatross wiki. Ah ye helium balloon! i like it. Imagine a spring you can charge up on the ground that slingshots you from launch, then solar powered from there.
 
kalvado
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Re: human-powered aircraft

Thu Nov 14, 2019 1:37 pm

jackmac wrote:
Appreciate the responses guys! Im definitaly going to look into the Albatross wiki. Ah ye helium balloon! i like it. Imagine a spring you can charge up on the ground that slingshots you from launch, then solar powered from there.

That spring is commonly called Jet-A.
Charging lithium battery for an hour by walking on a treadmill or elliptical can, in principle, give you a few minutes of comfortable flight.
 
jackmac
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Re: human-powered aircraft

Thu Nov 14, 2019 7:26 pm

I wonder if any progress was made on the albatross? after crossing the english channel and winning that prize they were probably satisfied. Do you know how the engergy from the pedals was translated to the propeller? I looked into the energy generated from pedals and it didnt look consistent i assume it wouldnt work well with a propellers speed jumping up and down. I read somthing somewhere leonardi da vinci had plan for a machine that worked off a persons legs kicking, seems like a more natural way to get energy out of human movement. I spose the running motion with swinging arms is the most natural human movement, but how to extract energy from that efficiently.
 
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Starlionblue
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Re: human-powered aircraft

Thu Nov 14, 2019 11:57 pm

There is a yearly competition for human powered aircraft, the Icarus Cup. https://bhpfc.org.uk/what-is-the-icarus-cup/

https://youtu.be/46qO443biCI
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
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TWA772LR
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Re: human-powered aircraft

Fri Nov 15, 2019 2:42 am

It hurts bad enough to fall off my bike...

That said, I'd love to operate a human-powered plane for the hell of it!
When wasn't America great?


The thoughts and opinions shared under this username are mine and are not influenced by my employer.
 
LH707330
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Re: human-powered aircraft

Fri Nov 15, 2019 3:55 am

jackmac wrote:
I wonder if any progress was made on the albatross? after crossing the english channel and winning that prize they were probably satisfied. Do you know how the engergy from the pedals was translated to the propeller? I looked into the energy generated from pedals and it didnt look consistent i assume it wouldnt work well with a propellers speed jumping up and down. I read somthing somewhere leonardi da vinci had plan for a machine that worked off a persons legs kicking, seems like a more natural way to get energy out of human movement. I spose the running motion with swinging arms is the most natural human movement, but how to extract energy from that efficiently.

Based on the setup, it looks like there's a chain drive that goes up to the prop shaft. Given that it's designed to spin at 75 RPM, I'm assuming the gear ratio is about 1:1, most cyclists have a cadence around 60 for mashers and 90 for spinners.

The big issue is this piece: "Allen completed the 22.2 mi (35.7 km) crossing in 2 hours and 49 minutes, achieving a top speed of 18 mph (29 km/h) and an average altitude of 5 ft (1.5 m)." Basically, you're hanging out in ground effect and going slow for a given power output. 300W for 29 km/h is pretty bad, I can sustain 33 km/h on my road bike for hours at 200W, and probably get up to 37ish km/h at 300W. Road bikes are infamously draggy, on a faired recumbent I could probably cruise at 50 km/h. Now let's say you want to climb out of ground effect: your run-rate power increase will have to increase to overcome the additional induced drag, and then you need extra power on top of that to climb. Looking at good climbers:

1800+ Vm/h: Lance Armstrong.
1650-1800 Vm/h: Top 10 / Tour de France GC or mountain stage winner.
1450-1650 Vm/h: Top 20 / Tour de France GC; top 20 on tough mountain stage.
1300-1450 Vm/h: Finishing Tour de France mountain stages in peloton
1100-1300 Vm/h: The Autobus Crew

Those are Tour competitors. Looking at some of my own Strava records, I've done 1603 Vm/h on short (few minute) climbs while outputting 459W, which translates to 87 FPM, on a road bike. Given that a road bike weighs less than a pedal plane (10 kg vs 32 kg) and suffers less induced drag while climbing a hill, we can assume that such a pedal plane will climb at a worse rate. Now, let's simplify this a bit and make some slightly optimistic assumptions:

Plane empty weight: 32 kg
My weight: 84 kg
GW: 116 KG
Power required for level flight: 300W
Surge power: 450W for 5 mins
Ergo surplus power for climbing: 150W

Now, if my recollection of physics is correct (someone correct me if not), then to lift a mass m I need F=m*g, where g is 9.8 m/sec^2. Also, P=v*F=V*M*g. Inputting what we know, we get:

m 116.00 kg
g 9.80 m/sec^2
F 1136.80 n
P 150.00 W
v 0.13 m/sec
v 25.97 FPM

Assuming we get a 50% efficiency on converting those extra 150W into climbing, we're looking at 13 FPM. I don't know if the pedal plane has any kind of gearing on it to keep the same crank RPM while increasing prop RPM, but there's got to be some max efficiency design point.

I may have messed those numbers up, someone feel free to correct them. Even if a pedal plane was similar to a road bike in climbing efficiency, accounting for the weight penalty I might get 50 FPM at 450W, then get tired after 5 mins and have to taper off to 300W and level off after climbing to a measly altitude of 250 feet.

Bottom line: humans have too poor a power/weight ratio to cycle fly to any realistic altitudes.

You might be able to get away with a newer design that has a better L/D than the Gossamer Albatross. If it's possible to get level flight down to 200W you might be in business, but climbing will still be awfully sluggish any way you slice it.

Edit: I checked the math for the hill climb on the bike example with an assumed 90% efficiency:

m 95.00 kg
g 9.80 m/sec^2
F 931.00 n
P 459.00 W
v 0.49 m/sec
v 97.03 FPM
e 90%
va 87.3233942 FPM

Looks like that part of it checks out, so unless my other assumptions are wildly off, that plane won't climb very fast....
 
26point2
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Re: human-powered aircraft

Fri Nov 15, 2019 5:36 am

I love cycling and climbing steep grades in particular but let’s leave Lance Armstrong out of the equation. He is a known cheat so his accomplishments don’t matter any longer. I’ve ridden with Armstrong a couple of times too, CO and HI, and he....let’s say...thinks highly of himself.

The Albatross hangs at the KIAD Udvar Hazy museum...at least it was there last time I visited. Cycled to get there too as a matter of fact.
 
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flyingturtle
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Re: human-powered aircraft

Mon Nov 18, 2019 4:15 pm

LH707330 wrote:
Bottom line: humans have too poor a power/weight ratio to cycle fly to any realistic altitudes.


Aww, this reminds me of the ornithology lectures I attended years ago. They used similar calculations to show that the weight limit of flying birds is at 15 kilograms. Above that, it is not efficient to fly. Swans and wild turkeys are hitting that limit. All heavier birds are flightless.
Reading accident reports is what calms me down
 
planewasted
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Re: human-powered aircraft

Tue Nov 19, 2019 4:16 pm

A human powered blimp would be cool. No effort for staying up in the air required. You could fly around with little effort and enjoy the view. But a quick calculation gives that a 6 meter diameter sphere would be required to lift 120 kg of blimp and human. Would turn out pretty wind sensitive. And helium is expensive. :grumpy:
 
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Starlionblue
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Re: human-powered aircraft

Wed Nov 20, 2019 11:16 pm

planewasted wrote:
A human powered blimp would be cool. No effort for staying up in the air required. You could fly around with little effort and enjoy the view. But a quick calculation gives that a 6 meter diameter sphere would be required to lift 120 kg of blimp and human. Would turn out pretty wind sensitive. And helium is expensive. :grumpy:


It's been done. And as you say, very wind sensitive.

Image
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
Sokes
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Re: human-powered aircraft

Thu Nov 21, 2019 4:00 pm

flyingturtle wrote:
LH707330 wrote:
Bottom line: humans have too poor a power/weight ratio to cycle fly to any realistic altitudes.


Aww, this reminds me of the ornithology lectures I attended years ago. They used similar calculations to show that the weight limit of flying birds is at 15 kilograms. Above that, it is not efficient to fly. Swans and wild turkeys are hitting that limit. All heavier birds are flightless.


Maybe 10 m wingspan and anywhere between 70-200 kg:

Image

source: https://en.wikipedia.org/wiki/Quetzalcoatlus
Why can't the world be a little bit more autistic?
 
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seat55a
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Re: human-powered aircraft

Thu Nov 21, 2019 4:58 pm

The Smithsonian built a half-size RC flying model of the pterodactyl in the 80s - with wing flapping action for control and maybe some propulsion.

https://www.nytimes.com/1986/01/28/scie ... o-air.html
 
Sokes
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Re: human-powered aircraft

Fri Nov 22, 2019 8:12 am

Starlionblue wrote:
There is a yearly competition for human powered aircraft, the Icarus Cup. https://bhpfc.org.uk/what-is-the-icarus-cup/

https://youtu.be/46qO443biCI


I wonder if Ryanair knows about it ?
Why can't the world be a little bit more autistic?
 
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flyingturtle
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Re: human-powered aircraft

Fri Nov 22, 2019 1:18 pm

Sokes wrote:
Maybe 10 m wingspan and anywhere between 70-200 kg:


Birds != Pterosaurs

Birds are homeothermic, and their feathers have the other crucial function of thermal insulation and regulation. If you can do away with feathers (which uses up a lot of nutrition to begin with), you can go for an extremely thin bat-like wing. The availability of food is another issue.
Reading accident reports is what calms me down
 
Sokes
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Re: human-powered aircraft

Fri Nov 22, 2019 2:07 pm

flyingturtle wrote:
Sokes wrote:
Maybe 10 m wingspan and anywhere between 70-200 kg:


Birds != Pterosaurs

Birds are homeothermic, and their feathers have the other crucial function of thermal insulation and regulation. If you can do away with feathers (which uses up a lot of nutrition to begin with), you can go for an extremely thin bat-like wing. The availability of food is another issue.


Good answer. I learned something.
Why can't the world be a little bit more autistic?
 
chornedsnorkack
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Re: human-powered aircraft

Tue Dec 10, 2019 8:51 am

Sokes wrote:
flyingturtle wrote:
Sokes wrote:
Maybe 10 m wingspan and anywhere between 70-200 kg:


Birds != Pterosaurs

Birds are homeothermic, and their feathers have the other crucial function of thermal insulation and regulation. If you can do away with feathers (which uses up a lot of nutrition to begin with), you can go for an extremely thin bat-like wing. The availability of food is another issue.


Good answer. I learned something.


Good but probably wrong.
Another solution proposed hinges on the pterosaurs being quadrupedal.
Their tracks show they walked on their wings on land, and while their hind legs were on ground as well, bulk of the weight rested on wings.
A limiting time for a bird is not just staying in air but takeoff. A bird needs strong legs to leap to air, but in air the legs are a load.
Whereas a pterosaur uses wings for leaping to air as well as flight.

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