Opinions on this (fictional) aircraft please...

[serpontaie]

My first thread; go easy

Anyway here goes,
Imagine a 6 engined pedal powered aircraft where 1 person sits in a pod under each propeller. They all power the beast which is roughly 55ft long with a wingspan of approximately 70ft! Made from Carbon Fibres and composites over a Plastic/carbon fibre frame.
This could be a nice project for some rich guy to work on! a bit of extortionate carbon composite here, some bicycle gears there, maybe 21 or sumin lol.

Max speed: 65mph
service ceiling: 1000ft
Empty weight: 125kg

I want opinions. Do you think it will fly or not

[fc82091]

maybe with a lance amstrong under each prop :p

[Buzz]

I am no experct, but wouldn't 60 mph max speed be way to low to get of the ground and stay in the air?

[jan_olieslagers]

I am no experct, but wouldn't 60 mph max speed be way to low to get of the ground and stay in the air?

Hm, I wouldn't title myself an experct either... But I don't think 60 mph is too slow for flying. Depends on design (wing profile, wing surface, &c &c). Just some thoughts:

mph is a rather unusual measure for airspeed, though not absolutely excluded: mph are indicated in my flying club's Piper Cub. But most common are knots (for PPL and airliners) and km/h (for gliders and ULM's) in Western Europe, at least. I understand the former socialist countries use km/h for all planes, and have wind in m/s... 60 mph would correspond to +/- 96 km/h, or +/- 52 knots. Quite reasonable! For comparison: the ULM in which I learn climbs and lands at 110 km/h, not too far from these 96 km/h. You might also look up the first motorised controlled flight by the Wright Brothers, what was their airspeed?

My doubts are rather in the "weight" corner: in small planes, a ratio of 0,5 between max gross/empty weight is a very nice figure, most planes only realise 0,6 or thereabouts. So I have my doubts about this hypothetical plane carrying 6 human engines, on average 80 kgs so 480 kgs load at least, versus an empty weight of only 130 kgs, even if there's no heavy engines, neither fuel tanks.

Above all: the o/p does have credit for posting an entertaining idea!

[NCB]

It can fly if aerodynamics make of it a giant glider.
Ideally, the human beings should be laying on their back.

At first thought, it would require separate control for the rudder as the rudder pedals are replaced by pedalable pedals.

The only issue is the take-off.
How is this glider going to pick up enough speed to lift off, and maintain enough power to climb?

The propeller will need to be run through an efficient gear system that would transform 1 pedal rotation into 20 rotations of the propeller to get decent RPM (which could be doable since the propeller is only subject to propeller/air drag compared to weight/ground friction drag on the bicycle) and the longitudinal plane motion of the pedals converted into a vertical plane movement of the propeller.

[YYZ727]

In 1979, a guy succeeded in crossing the Channel on a pedal powered very light aircraft. His Vmax was nowhere near 60 mph, his average FL something like 5 feet !

http://en.wikipedia.org/wiki/Gossamer_Albatross

[jan_olieslagers]

The propeller will need to be run through an efficient gear system that would transform 1 pedal rotation into 20 rotations of the propeller to get decent RPM (which could be doable since the propeller is only subject to propeller/air drag compared to weight/ground friction drag on the bicycle) and the longitudinal plane motion of the pedals converted into a vertical plane movement of the propeller.

Hm. What do you consider decent RPM for the prop?
What's the base for your 1:20 ratio?
What prop diameter were you considering?

[NCB]

Hm. What do you consider decent RPM for the prop?
What's the base for your 1:20 ratio?
What prop diameter were you considering?

The idea is that the propeller needs to push backwards as big a mass of air as possible.
1:20 is just a number out of nowhere that will give an RPM of 2400 if the human being can achieve 2 pedal rotations in one second. Of course, propeller diameter, propeller pitch, efficiency of the gearing mechanism and other parameters will determine how hard it will be for the human being to kick through the pedal.

The idea is not as crazy as it sounds.

You take a bicycle that goes 70km/h.
That is about 20m/s.
The circumference of a traditional bicyle tyre is around 2m.
When the professional biker kicks out 70km/h, the tyre is rotating at 10 rotations per second or 600RPM.
In my opinion, air/prop does not offer the resistance to movement that ground/bicycle offers, simply because the weight factor is factored out.

[serpontaie]

keep the ideas coming guys! I dont know about u lot but i reckon both human powered and solar powered aircraft could be a hit in the future

[chornedsnorkack]

My doubts are rather in the "weight" corner: in small planes, a ratio of 0,5 between max gross/empty weight is a very nice figure, most planes only realise 0,6 or thereabouts. So I have my doubts about this hypothetical plane carrying 6 human engines, on average 80 kgs so 480 kgs load at least, versus an empty weight of only 130 kgs, even if there's no heavy engines, neither fuel tanks.

The 1 person human powered planes have had empty weights in the range of 30...40 kg. How would they scale?

[jan_olieslagers]

Not bad that, carrying a 80-90 kg human power plant on a 30-40 kg empty weight.
Scaling woud be slightly favourable, to my non-experct eye: largely economy of scale, the one plane still requiring one single (set of) rudder & ailerons & flaps & landing gear & whatever, however many the crew/load.

[jan_olieslagers]

keep the ideas coming guys! I dont know about u lot but i reckon both human powered and solar powered aircraft could be a hit in the future

For recreational flying, perhaps, yes. For transportation purposes I'm less hopeful. To be able to cope with adverse weather, a lot of power reserve would be required.

PS quality spelling might inspire the quality of answers.

[regi]

I will make some suggestions to my booking agent for my next flight to Johannesburg, 10 hours peddling.

[serpontaie]

PS quality spelling might inspire the quality of answers.

What did i blumming well spell wrong??? all i can see is sumin, tht just means something...(in yorkshire talk)

[earthman]

I am no experct, but wouldn't 60 mph max speed be way to low to get of the ground and stay in the air?

The Antonov An-2 has no reported stall speed, it can perform fully controlled flight at 30 mph. You can fly it backward if flying into a headwind of over 30mph.

[AF036]

it's called human-powered aircraft (HPA)

http://en.wikipedia.org/wiki/Human-powered_aircraft
http://www.humanpoweredflying.propdesig ... ights.html

The Antonov An-2 has no reported stall speed, it can perform fully controlled flight at 30 mph. You can fly it backward if flying into a headwind of over 30mph.

You can fly anything backward if the head wind is higher than the airspeed!

[earthman]

it's called human-powered aircraft (HPA)

http://en.wikipedia.org/wiki/Human-powered_aircraft
http://www.humanpoweredflying.propdesig ... ights.html

The Antonov An-2 has no reported stall speed, it can perform fully controlled flight at 30 mph. You can fly it backward if flying into a headwind of over 30mph.

You can fly anything backward if the head wind is higher than the airspeed!

Yes of course, but for most aircraft that headwind needs to be really strong to be faster than the stall speed, definitely much more than 26 kts.