Has it been done already? ... and what's new?!

To any eager readers: my sincerest apologies for the extended delay between this post and the prior. In all my free time between trying to save Alcator C-mod and the US nuclear fusion program, moving to a new apartment, and trying to keep my post-doc together, I've still kept myself busy with this flying motorcycle project. A man's got to do something with his weekends, right? So, on with the progress report!


I visited the March monthly meeting for chapter 106 of the experimental aircraft association to see a photo presentation by Lane Wallace, scored a signed copy of her book, and met and chatted with several experienced aircraft builders at the meeting including Mr. Richard Gersh, a VP of Business Development at Terrafugia. Mr. Gersh let us know that Terrafugia is planning to show their prototype at the NY auto show, and that they would have a photo-op session in Times Square on the way to the show on April 1st. I also heard about the Charles River RC club at the meeting, and Wick's aircraft supply and aircraft spruce, where you can find just about everything you need to build a plane.

MIT also has several great resources for the would be experimental aircraft builder. There is an MIT Flying Club, through which I've enrolled in free ground school (MIT 16.687) for my private pilot's certification. There is also the Wright brother's wind tunnel at MIT in the aero/astro department, which I'll try to make use of for testing some scale models of a flying motorcycle. The same department also has expertise with composite materials which I'm hoping to partially assimilate.

After meeting the flying folks, and sizing up the offerings at MIT, I've wondered again if there might already be flying motorcycles out there that I haven't heard of. There are at least two companies with candidate prototypes for flying/road-going automobiles: Terrafugia’s Transition, and the Dutch PAL-V. There's a January 29, 2012 article about the Terrafugia transition in CNN, a great TED talk by co-founder Anna Mracek Dietrich, and a promo video for their 'roadable aircraft'. I don't know as much about the PAL-V, but I'm certainly interested in their propeller. Check out the videos and websites of both aircraft below if you're further interested.

Terrafugia Transition

Dutch PAL-V

There are several other interesting contenders for neat ways to get around, including Moller’s Skycar, Samson Motorworks’ Switchblade, the Hover-bike. Some have also stowed collapsible motorcycles into regular small aircraft, but in addition to added weight, this design deprives the pilot of the great outdoors. Drifting further away from flying motorcycles, there are also human bird wings, vacuum tunnels, and super fuel efficient planes. All of these are unfortunately not two-wheeled road-going aircraft, i.e. motorcycles, though. How does that make us feel?

 

see theoatmeal.com

You decide which of these best describes my feelings about there being no flying motorcycles in the world.

Strangely enough, some of the wilder motorcycle folks around have even mounted a turbine engine to two wheels, resulting in a motorcycle which can outrun a MIG fighter on a runway, but for some reason they didn't bother to go the extra mile and attach wings. WTF guys?! There are all sorts of badass custom motorcycles around, so where are the wings already?! Oh yeah, I guess that's me huh?

On the bright side, the glider is well on it's way to flying high. Somehow, the designer didn't include AILERONS, which I guess is maybe a standard 2 meter glider thing? Maybe it's more badass if you can fly with only two control axes? Well between you and me, I think it will be bad enough ass to be flying a motorcycle, and there will probably be enough problems and challenges even with all three axes, so I'm modifying the plans to include ailerons. And while I'm at it, maybe I'll skin the whole thing in a super lightweight fiberglass instead of monokote or that polyolefin heat shrink roll I bought. Turns out polyolefin is great for labeling bottled beer, but isn't quite elastic enough for skinning a plane. Oh well.

Photos of glider progress at my secret lair in New Hampshire

Until next time, maybe I'll check out some sky diving lessons to tack onto my flying lesson which I still haven't gotten around to. Hopefully the warmer spring weather will bring me around to the airfield soon so that I can do both in short order. Probably the X-plane and turboCAD orders can wait until the fall when I'll want to spend more time inside again, and hash out some patents or something right? When the time comes, it looks like a raspberry pi (available at Newark.com), might make for a nice lightweight flight computer, but for now I think I'll be OK with my 2.4GHz radio and servos. Anyway, I'll do my best to have the glider operating next time!

FOLLOWUP EDIT: Thanks to Ron for pointing out DIY Drones and their ArduPilotMega Arduino powered programmable autopilot! This is quite an amazing package for $200: a MediaTek MT3329 10Hz GPS, a Honeywell HMC5843 3-axis digital magnetometer compass, an Invensense MPU-6000 six-axis gyro and accelerometer, a Swiss temperature corrected barometric altimeter, all of these are digital too! There's even a little pitot tube addon so you can do airspeed feedback. Rad.

Keeping it real

Let's consider some actual present day small aircraft and motorcycles to see how realistic this crazy idea is.

A low weight target and one of the oldest and best planes around (many still flying today!), is the Piper Cub. The slightly larger Cessna 150M is probably a bit closer in final weight to what a flying motorcycle would be. As of this writing, the most produced small aircraft in the world was the Cessna 172, with over 43000 built by 2010. These aircraft have the following general specifications for comparison:

Model	Piper J-3 Cub	Cessna 150M 1977	Cessna 172R
Length	6.83m	7.3m	8.28m
Wingspan	10.7m	10.2m	11m
Height	2m	2.6m	2.72m
Wing area	16.6m2	15m2	16.2m2
Empty weight	345kg	504kg	767kg
Max takeoff weight	550kg	730kg	1111kg
Powerplant	48kW	75kW	120kW
Power/weight	0.139kW/kg	0.149kW/kg	0.156kW/kg
Propeller diameter	?	1.8m	?
Cruise speed	121km/h	198km/h	226km/h
Stall speed	61km/h	78km/h	87km/h
Range	354km	678km	1289km
Fuel consumption	?	23L/h	?
Lift to drag	?	7 minimum	?

So now that we have some planes on the table, let's consider some motorcycles from most common to most exotic/awesome. The Honda CBR1000RR is a common screamer, and not too heavy. While the company started out making aircraft, BMW's motorcycle line has strayed quite far from that original task, weighing in at the heaviest of our presently considered bikes, and less power than the Honda. The next two bikes are substantially lighter, and probably reflect the lowest possible weights since they were developed for racing.  While the Norton only has a 588cc engine, it sports a Wankel engine which generally produces roughly twice the power per cc as a four stroke engine while also being lighter and having less moving parts to fail, all bonuses for flying machines. The last in our lineup is the Britten V-1000, a famous feather-light carbon fiber and kevlar framed racing motorcycle, which just screams of the 80's including (unfortunately) the lowest power engine of all our motorcycles.

Model	Honda CBR1000RR	BMW K1300R	Norton NRV588	Britten V1000 (1989)
Engine type	999cc liquid-cooled inline four-cylinder	1293cc liquid-cooled inline four-cylinder	588cc twin-rotor Wankel type	Water-cooled 999 cc 60 deg V-Twin quad cam 4-stroke
Wheelbase	1410mm	905mm	?	?
Seat height	820mm	820mm	?	?
Fuel capacity	17.8L	19L	?	24L
Curb Weight	199kg, road ready, fully fueled	243kg, road ready, fully fuelled	150kg guess with fluids (reported 130kg dry)	138kg with fluids
Power output	133kW @12000 rpm	129kW @9250rpm	126kW @11500RPM	101kW@9500RPM
Power/weight	0.668kW/kg	0.531kW/kg	0.84kW/kg	0.732kW/kg

An interesting point to make from these comparisons is that almost all of the motorcycles have more power than even the largest plane, except for the Britten which had an inferior engine from the 80's and probably made more smog than the whole lot. While the motorcycles are all of course much lighter than the planes, it seems reasonable at first glance that we should be able to fix a pair of wings, a tail, and a prop onto one for a cost of around 100kg, which would still make them lighter than the lightest plane up the page. Now for aerodynamics, probably the motorcycles are a bit shy of optimum, but just about everyone around has seen a motorcyclist hauling down the highway at 100mph (~160kph), and with some appropriately molded fairings, a motorcycle could probably rival a typical small plane for aerodynamics.

After all this talk about flying things, I think I'm going to buy myself a Great Planes Spirit 2 meter balsa sailplane kit for my birthday, to complement the 1hr flying lesson Deborah got me. It's sort of a pain that the online hobby shop says you need 'covering tools' (ie a heat gun and/or iron) and '2+ rolls covering' (ie lightweight shrinkwrap), and these things aren't obvious purchases on the webpage. Good thing my favorite online hardware store ever, McMaster-Carr (seriously that's not a paid advert, they just kick ass, like you buy something in the morning and it's on your doorstep that afternoon style ass kicking), sells polyolefin heat shrink wrap and heat guns. A 500ft roll is probably way more than I need (for the first plane anyway...), but it costs as much as the small folds that hobby stores sell. Hopefully that's all I need! 

a Great Planes Spirit 2 meter balsa sailplane

Heat shrink wrap and a heat gun as depicted by McMaster-Carr

After this one's finished maybe I'll do a replica in carbon fiber to beef up my composite materials experience. More on that next time.

UPDATE: Polyolefin heat shrink doesn't seem to be well suited to structural wrapping due to its low elasticity and general weakness of heat welds. I'm going to pick up some of the PVC heat shrink which will hopefully work better.