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Discussion Starter · #1 ·
Hey all, I'm looking to gauge interest on this project and figured a sport bike forum would be the place to start. I hope it doesn't come off as spammy, but here's a link: https://www.indiegogo.com/projects/personal-quadcopter-skycycle-engineering-build#home

My plan is to build one of these off of a sport bike platform, and it will be capable of lifting a nice amount and cruise around the sky. The idea is that a control system will handle of the actual hard calculations needed for a safe flight.

Let me know what you think
 

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gonna be loud as hell, inefficient as hell, and dangerous as hell.

and those are the good points.

Fuel type/delivery? Engine type? weight? a sportbike platform is a very bad idea, as they are heavy enough as it is. remove the body panels, the engine, and fix the handlebars, then run hand controls from there. You wanna be down to a frame and seat, essentially. no forks, no swingarm.

From there, the props are obviously going to have individual motors. How are you planning to fuel them?

there are a myriad of problems with this design. And I'm a layman at best. the aviation guys here will shred this. However, if you CAN make it work, well, the skies will get much more dangerous very quickly. :D
 

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First off, you need to ditch everything motorcycle related aside from the engine, ECU, and probably the harness. You need to redesign a full frame around the engine mounting points, which differ from bike to bike. Then do an FEA on it and modify from there.

Your frame also has no lateral or torsional support, so it will flex and bend like hell, especially with the torque applied from the rotors.

I'm assuming you are a software/controls guy. I would get some design input from a structural engineer first and foremost.

Add in the fact that motorcycle engines are not rated for aviation duty, and it starts to get dicey. You don't want an engine going out when you are several hundred feet in the air. There's a reason why aviation engines cost so much.
 

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There is someone in NZ that has got to the point of tethered flight with a similar project. Biggest issues been power to weight, how much fuel/endurance are you planning on having? I guess the software for quad copters are readily available now days the only other question is in the event of a failure how would you initiate auto rotation?
 

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Discussion Starter · #5 ·
Predator! I appreciate the honesty. First off the pictures that you have looked at are only a mockup, not the official design. It will be loud, and may be inefficient, but none of that will matter if it's dangerous. I know the idea of a flying motorcycle doesn't scream safety, but safety will remain a major factor in its design.

I've been running my numbers at about 450lbs including rider, this would be about 300lbs machinery, 150lbs rider. The heart of the design will be a combustion engine that turns a set of generators that will in turn power the electric motors for each prop. I haven't worked out the details such as exact engine and mechanics, but the concept is in place. I actually totally agree with most of what you said, and most of it will be worked out in the design phase. The idea was to raise funds for the engineering phase and then spread the wealth of knowledge to the contributors.
 

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Ok, some rough numbers here. A sportbike engine is roughly 100lbs (Busa would be 125lb).

Going off of your sketch, it's looking like your top tubes are 6" diameter, and I would assume you are using 6061 Sch 40 Aluminum for weight, which is 2.76lb/ft. Looks like you have roughly 7' long outr******, plus a 1ft and 2ft piece of 6" pipe, which would be about 10ft for each outr*****. That's a bit over 100lbs there. Again, this is just an assumption based off the photo. I have no idea if that is even strong enough for this application yet.

Add in 4 motors, propellers, prop shrouds, alternator, additional framing, controls, seat, gauges, cabling, fluids, and various other odds and ends, you will not hit your 300lb goal. I would say probably 400lb at a minimum.

I would aim a bit higher on weight, and look for as much power/lb as you can get. Hayabusa motor will provide about 100ftlbs of torque and 170hp. Should be enough to drive a major alternator.

If you have any other concepts you are thinking about, or various pieces, throw them up here. Right now I'm just going off of one photo.

Background: I'm an engineer, dealing mainly with weight calcs and structural engineering at this time. I have most of an Aerospace engineering degree as well (double major and then decided to go to single major instead before graduating), so I should be able to help you on many things before diving too far into the weeds.
 

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Discussion Starter · #9 ·
Arcticamt6! All good points. The lateral support will be critical due to the gyroscopic forces of the props. Like I was telling Predator, the design you see is just a mockup and will be worked out in a proper engineering phase.

I have more of an electrical background, with a hint of software/mechanical, sort of an all around electromechanical.

Nero! I am unfamiliar with the project that you are referring to, unless it is the Moller Skycar, in which case I though was US based. I've been looking into the Skycar (which has been in progress for 40 years) and they are supposedly looking to fly it this June, so I'm excited for that.

You're absolutely right about the existing software for quadcopters, it's all been worked out, but will obviously need to be reworked for scale applications. Also, good catch on the autorotation, as long as the blades are able to over pitch you could actually run out of gas in midair and make a safe landing.
 

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On the autorotation problem. The only time this would be needed is if one of the electric motors went out. Electric motors are much more durable than gas motors so this shouldnt ever be a problem but you would still want it as a "just in case". If you run out of gas or the gas engine that runs the alternator goes down then you could still get to safety on battery power already stored. At least I would figure it was designed with battery backup in case of main engine failure.

As for the engine you would use I dont think the busa engine would be the best. You could go with a lighter engine that has higher RPM's with the same type of output numbers. The higher RPMS would charge better I would think however if you are more interested in torque than RPM then you would still have a few choices that I think would be better. Honestly you might be most interested in a motor that is really good for gas consumption and has high torque at low rpm to keep noise down and give you more time with the same fuel tank. Then you take the high torque low rpm engine that does good for gas mileage and gear it proper to spin the alternator just right. Keep the stress on the engine down by putting it in just the right rpm range while keeping the alternator spinning at the right speed. On top of all of that keep the weight as low as possible.

Lots of things to figure out but it could be done. Safety would be a huge issue though.
 

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You would be better off using some type of VTOL jet engine, sort of like a Harrier jump jet. or the F35.
 

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Maybe the gas engine powers an electric generator that powers the electric motors for each rotor?
 

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Discussion Starter · #17 ·
Maybe the gas engine powers an electric generator that powers the electric motors for each rotor?
This is the concept that has already been designed.

This most certainly is not a personal attack on you but this is pretty telling.

$150USD
RAISED OF $35,000 GOAL
0% 18 days left
YamahaFreak, what is it telling? It certainly tells me that I'm not building much without meeting the crowd funding goal that I set.

f*** aluminum.

Build it outta pure European carbon fibre.
Yes! Obviously the cost would shoot up, but carbon fiber is the choice material for construction. The only issue with that is getting everything custom seamed together as opposed to using bulky metal joints that would increase the weight anyway.

Solution:

https://www.youtube.com/watch?v=8AkUFNDeRMY



As an aviator.... if safety is a priority, abandon the quad-copter design.
Mulletman, that is actually a great solution. I didn't know that type of transportation existed in "car" form until now. Seems actually very stable from the video, but requires a lot of setup and a lucky wind to get the parafoil pressurized.

On the autorotation problem. The only time this would be needed is if one of the electric motors went out. Electric motors are much more durable than gas motors so this shouldnt ever be a problem but you would still want it as a "just in case". If you run out of gas or the gas engine that runs the alternator goes down then you could still get to safety on battery power already stored. At least I would figure it was designed with battery backup in case of main engine failure.

As for the engine you would use I dont think the busa engine would be the best. You could go with a lighter engine that has higher RPM's with the same type of output numbers. The higher RPMS would charge better I would think however if you are more interested in torque than RPM then you would still have a few choices that I think would be better. Honestly you might be most interested in a motor that is really good for gas consumption and has high torque at low rpm to keep noise down and give you more time with the same fuel tank. Then you take the high torque low rpm engine that does good for gas mileage and gear it proper to spin the alternator just right. Keep the stress on the engine down by putting it in just the right rpm range while keeping the alternator spinning at the right speed. On top of all of that keep the weight as low as possible.

Lots of things to figure out but it could be done. Safety would be a huge issue though.
Demon Duck, from the start the idea has been stay away from batteries. Batteries are heavy and the amount I would need for sustainable flight would increase almost exponentially the more expected flight time, BUT they are able to deliver a relatively insane amount of power when needed. That being said, the system will obviously need a battery in the engine's circuitry to work the combustion properly. From what I've read up on autorotation, it's either all or nothing. The blades are pitched to maintain speed with the uprush of air, and as the ground is approached, the blades pitch back up again, using "stored" rotational energy to break the downward force of the vehicle. With that in mind, feeding energy in to a prop that is essentially pitched in the wrong direction will make the vehicle fall FASTER. This will add to the downward energy of the vehicle and probably cause more stress on flight components. If there were an ideal point to add energy to the system, it would be right before the ground when the blades are gradually pitched back to normal.

The idea behind the Indigogo campaign is to raise money for a feasability study and then go from there. The concept is in place, and if you want an inspirational video then watch this real quick: https://www.youtube.com/watch?v=77uK19KxMuI . According to this video, TWO of these RC Helis are able to lift a 60kg woman. Think of my idea less like a motorcycle with helicopters attached to it, but more like four of these helicopters attached tail end with all of the power components merged in the center and a seat to sit on.
 

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Discussion Starter · #18 ·
Most generators run at a very specific RPM simply whacking on a higher power motor with more RPM won't nesscarily be useable.
Right, I'm not just throwing components together here. Each component has a pretty specific range of RPM where its efficiency is at its peak.

One thing to note: Most vehicle components are not designed with constant RPM in mind, specifically engines. Running a regular combustion engine at a constant high RPM will ruin it in no time. Everything in an aircraft engine has been designed to maintain a constant RPM, power output, etc. That combined with aircraft grade power generation systems, or even better, a custom generator designed to maximize power output from the engine at its peak RPM, will result in a pretty stable power system.
 

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Mulletman, that is actually a great solution. I didn't know that type of transportation existed in "car" form until now. Seems actually very stable from the video, but requires a lot of setup and a lucky wind to get the parafoil pressurized.
You wouldn't need a lucky wind, just the knowledge of where the wind is coming from. There would be a bit of legwork in laying out the 'chute... but I can't imagine it's that terrible.


My issue with the quad-copter is the dependence on the most of the same parts for both lift and control. Without cyclic or collective controls, an autorotation is unlikely. If you lose one of your four props/motors/drivetrain, you're down 25% on power as well as being asymmetric, and you're also down control on that side, as well as the side that opposes it.

Separate flight from control and you'll have a somewhat safe vehicle.
 
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