Q: Your Jetbike uses a propane-fired Gluhareff jet engine of 20 pounds thrust. How did you decide on that type of engine and that power range?
A: The Gluhareff engine is superior to the "pulse-jet" type because it has no rotary valve to wear out. The G-8 also does not require an electric motor to spin-start the engine like other types. It also uses clean propane fuel, which is well-contained in a standard tank, instead of kerosene, which has the potential for leaving residue everywhere and causing a fire hazard. I chose the 20-pound model because the price was right (about $950). The 40-pound model was about $1,600 and I did not see any added benefit to the greater thrust. Plus, the larger engine would have required a bigger, heavier fuel tank.
Q: What's the capacity of the tank you're using? And how much burn time does that give you at full throttle?
A: The tank is a standard 5-pound (almost 1 gal.) cylinder. At full throttle, it lasts about three minutes. That's about 1.6 lbs/min consumption at about 1000 feet above sea level.
Q: Can you go through the pre-launch operations of a Jetbike run for us?
A:: The first step is to bump up the pressure in the propane tank to 275 psi using a nitrogen tank and regulator. I then attach the tank to the bike and hook up the gas fitting. Following that, I suit up and cross my fingers for good luck!
Q: What's it like to climb into its saddle and
light it up: noise level, G-forces, etc?
A: The moments leading up to a Jetbike run are quite a rush of adrenaline. Usually the run takes place in a suburban area where it creates quite a sensation.
I'm not sure if the Jetbike is legally considered a "motorized bicycle" for the purposes of registration or not. I haven't been to the DMV to get plates yet. I can just see the puzzled look on the face of the poor soul working there. Now, are you NUTS or something, man?
I am always eager to keep the runs limited to a three-minute tankful. I then seek the safety of a garage and watch the patrols drive slowly by.
I am also somewhat apprehensive about the safety of this device. I haven't had any scary experiences yet, though. Let's just say that, while riding, I am constantly aware that I am nearly sitting on a metal container full of flammable liquid with an extremely loud blowtorch pushing me along. The noise is comparable to "front row center" at Boston's Logan Airport. The acceleration is gradual, but once it reaches 25, I become aware of the considerable amount of inertia that I am building up on a lightweight, slightly rear-heavy vehicle. The back end likes to hop and sway. Straight runs are a must.
All said, I highly recommend a ride like this one for anyone who likes to tinker, is not afraid of propane, and likes to create a stir in their neighborhood!
Q: I guess that also answers the question "Is that Nomex/chrome suit necessary,or is it just a Futurist fashion statement?". Is the current machine Mk.1 of a progressive development scheme, or have you reached your design goal with this one, aside from tweaks and refinements?
A: Yes, the nomex hood, nomex gloves, helmet, and army surplus firefighter's suit are my insurance against being "patient of the year" at the local burn ward. I highly recommend this get-up to anyone considering jet-powered vehicles.
I am comfortable with the design-and-build progress that I have made. The Jetbike was born out of frustration with the Jet Go-Kart. The G8-2-20 just isn't powerful enough to push something as heavy as a Kart. So, as you can see I had to re-invent the wheel twice here. The engine is perfect for a lightweight bicycle, however. I think that I will now be spending more time riding and less time making major modifications.
Q: Where were the most recent photos taken? And what's next for the Jetbike?
A: I haven't made it to Pike's Peak yet. I did test it out in Idaho Springs, Colorado at the Colorado School of Mines' Edgar Experimental Mine. Testing the bike at night really provides some useful information regarding the relationship between the temperature of the jet's exterior and how well it is performing. I am happy to say that it runs well at 7,500 feet elevation!