Thrustcycle demos new version of its self-balancing SRT
By Ben Coxworth
14:46 December 9, 2011

Thrustcycle has unveiled a new version of its self-balancing inline-wheeled prototype electric vehicle, the SRT
Image Gallery (2 images)Back in August, we heard about a self-balancing prototype vehicle known as the Thrustcycle SRT. Utilizing a flywheel-based gyroscopic stabilizing system, the electric vehicle was able to remain upright on its three inline wheels, even when standing still. The flywheel also served as a kinetic energy recovery system, helping to extend the vehicle's range by storing energy that would otherwise be lost when braking. Now, four months later, Thrustcycle Enterprises has contacted us with information about the latest version of the EV, and provided some video of it being driven around ... and getting the crap kicked out of it.
Unlike the previous prototype, the new SRT has just two main wheels, one in front of the other. Power is provided to the front wheel, while steering is accomplished with the rear. Wheeled outriggers have also been added on either side, presumably for added security should the flywheel stop, or to provide support in sharply-banked turns.
Whereas the other vehicle was open to the elements on the sides, this one appears to be more weather-resistant, with an enclosed body featuring a clear domed canopy on top. According to the company, future prototypes should incorporate more practical considerations, such as a lighter carbon fiber body, retractable side wheels, lights and turn signals. There are also plans for a front wheel-steered scooter, along with flywheel-powered watercraft and a hovercraft.
In the meantime, check out the current version of the Thrustcycle SRT in the video below. Although the driving footage is rather ... sedate, the vehicle does a fine job of keeping itself upright while someone attempts to kick it over.
There is certainly something interesting and notable going on here, but they really need to bring in a designer to create an exciting body and easy entrance and exit if they want to generate any commercial interest.
What a pity to spend so much time and effort, and not a small amount of money too, on something with such a serious design flaw as rear wheel steering - positively lethal.
All they have to do is put in a reverse gear and problem solved -- front steering and rear wheel drive. Might need to turn the drivers seat around also ;-)
This is obviously just a proof of concept for the flywheel stabilizer and energy recovery. That is the 10% of the job to designing a real product, but a nice concept demo.
Why oh why did they choose rear wheel steering? There must be a reason, perhaps they want to make it safer to do high speed reversing? I don't get it.
The body still needs refinement and maybe a lambo style door. The stability is good and hopefully the power to weight ratio is approaching 36 lb/hp with rider. The body can be cleaned up so the Cd is below 0.15. The kick test showed a fair amont of side compliance in the suspension system but this easy to fix. The rear steering is viable IF the castor geometry is correct. See the chapter on rear steering in Wilson's "Bicycling Science". The steering axis is angled forward and the trail is best BEHIND the steering axis. I would want a larger diameter rear wheel and at least 4 inches of well dampened travel. Remember, people used to think riding more than 30 mph caused suffocation!
Rear wheel steering has always been considered highly unstable.Our gyro system eliminates that inherent instability.In short, "We did it because we could".
Heh the reason for rear-wheel steering is more diabolical than that.
I read into the Thrustcycle website and I found a respectful reference to Buckminster's Dymaxion!
People here may not realize it or remember it, but the Dymaxion was a 3 wheeler tadpole with, you guessed it, rear-wheel steering.
If you watch some youtube footage of Buckminster, there's at least one shot of him tooling down the highway with his hands completely off the wheel.
Single track vehicle dynamics are not completely or even well understood.
What I find exciting about Thrustcycle's gyro stabilizer is that it could make, for instance, the Acabion a viable road vehicle.
Not that I would condone a missile like that being licensed for road use in my country... :)
NHTSA tried rear wheel steering for a test motorcycle many years ago. Kenny Roberts (national champ, world champ, etc...) couldn't ride it, the whole idea was tossed.
Also, Bendix Corp. tried the same thing on a bicycle, same result. REAR WHEEL STEERING FOR TWO WHEEL VEHICLES HAS BEEN TRIED AND DOES NOT WORK.
I think the speed was limited by this factor, and only possible because of the mechanized stabilization.
Rear wheel steering works quite well at any speed with our gyro system correcting the imbalance. However, we never intended to make a production vehicle without a more conventional front wheel steering system.Without our gyro system in operation, rear wheel steering is impractical and very difficult to control.
http://cobbsblog.com/gyro/gyro-x-menu.html Alex Tremulis (think Duesenberg, Cord, Tucker, Chrysler Thunderbolt, and more) and Thomas O. Summers, Jr, (holder of several dozen basic gyroscope patents), they build Gyro-X, a gyroscopically stabilized 2-wheel car offering superb performance and efficiency. Science and Mechanics September, 1967 issue.
re; Thrustcycle E1 - December 13, 2011 @ 06:38 am PST
In all fairness I did not think that you had not solved mechanical problems with rear wheel steering but my experience driving and be hit by a forklift is what convinced me that rear wheel steering is a lethally bad idea for almost anything but a forklift.
Wow, that Gyro-X is a really neat car! I'm certain I saw that magazine cover before.
Unfortunately, the blogger only lists two possibilities why Gyro-X had failed (government cover-up vs impracticality).
Really, what killed the Gyro-X is lack of investment, leading to lack of cars available for potential customers to examine and to buy. Unfortunately this is the same thing that killed the Aptera. The harsh, brutal reality is that real businesspeople produce a product that people subsequently buy. So there's the two ingredients that were missing: nobody was able to buy a Gyro-X (or an Aptera), and you could arguably say that was (at least partially) because no saleable examples were ever produced. Why was there no investment? Because everybody knows that people are fickle and there was not enough assurance that people would ever buy those odd ducks. Even if Aptera was sitting on hundreds of pre-sales. Too risky.
Better picture of 1912 Wolseley Gyro:
http://www.wolseleyworld.com/oddities-gyrocar.php
Better picture of 1967 Gyro-X:
http://zgeek.com/showthread.php/82384-A-look-at-monotraces-Pt-2-The-Gyrocars
Aptera killed the original designs and was going with a "Camry look-alike."
At some point you have to stop designing and start building.
This is a great step forward.
it needs to consume energy just to stay in one place. Surely it would have been easier to just add a 3rd wheel.
and as someone who recently tried to ride a scooter backwards, it's suicidal to have rear-wheel steering.
For self-balancing, inline wheels etc - have a look at Louis Brennan's ideas from the early 1900\s
http://www.aqpl43.dsl.pipex.com/MUSEUM/LOCOLOCO/brennan/brennan.htm
I'm guessing this is a proof of concept vehicle for the gyro's.They might of missed the boat on the rear steering,considering the variety of front suspension's available for motorcycle's.Lit Motor's is a little further along with the development of their gyro stabilized motorcycle,well at least it is a design you could see yourself driving to work or to the store.But I wish them all the best,because in the end,we don't need a big 4 door car hauling one person to work,or getting a movie at the video store.
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It's nice to see that they fixed the off center forward vision but the rear wheel steering is still asking to kill someone.