Posted on July 4, 2010

       Hello again folks!!! It’s been a while since I had the chance to share some news about the GRV-2 jet bike. Wet weather this last winter had kept me from testing the bike at my favorite proving grounds, El Mirage dry lake. Now that the weather has cooperated and the lake bed surface is solid I thought it would be a good time to test out the GRV-2’s newly installed afterburner.
       The last time I ran the GRV-2 on the lake bed it was producing about 51 pounds of static thrust. Since then I have reconfigured the GR-7 with an afterburner which increased it’s thrust about 31%. That means that I now have 67 pounds of thrust to push me down the lake bed and hopefully beat my last “record” of 52.1 MPH.

       Organizing the big day to retest the GRV-2 took some planning. I had to synchronize seven peoples schedules and miss all of the holiday weekends to plan this event. After several shot down dates we were able to agree on June 26 which happened to be two days after my ten year wedding anniversary :0P After the date was locked in I spent a solid week preparing the GRV-2 for the big day (not on my anniversary day of course ;0).
       The first order of business was to test run the GR-7 which had been sitting in a trailer for months. Amazingly the GR-7 fired right up the very first try which was an incredibly proud moment for me. After sitting for so long the engine spooled up and settled in at idle speed without any assistance :0) It was at this moment that I realized exactly how cool this creation is and that it was well worth the effort to build :0)
       Once I was sure the GRV-2 was mechanically sound I moved on to the support equipment and supplies. I rounded up all of the tools and fuel needed for the day and even included a surprise for my long term readers. Everything was in order for the speed trials and needless to say I was excited!!!

       The crew showed up at the house just after 5:00 am Saturday morning including my brother Mike, my good friends: Kent Gallacher, George Manning, Andreas Blaser (and sons: Erik and Sven), and Andreas’ friend Evan Brinton. We cruised up to the lake bed and started setting up camp just shortly after 6:00 am.

       As you can tell by the photo above I had brought my GRV-1 “Turbotug” to the party. I had decided to unveil my secret purpose for the tug on this day sporting a brand new bike trailer that I had built late last year. The tug’s new role as a support/tow vehicle for the GRV-2 is incredibly fitting as it will save fuel in the bike by towing it to the start line before each run. In a way it brings all of my turbine research into one complete package :0)

       While my brother and I were setting up the equipment Andreas and sons were busy setting up the cones that marked out the 5000’ course. These cones are a very important guide for me to follow during my runs. Without the cones it would be very difficult to guarantee that I would not hit any holes or unexpected ruts in the lake bed. By pre-driving the course along the cones I can determine the safety of the path I will be traveling at high speed.
       The cones also help to identify the course location to onlookers which is an important safety issue. It is never good when a vehicle crosses your path when you are rocketing down the lake bed :0/ Of course a properly prepared crew can help prevent such a disaster by waving off stray traffic. Luckily there were very few people willing to brave the heat that day making the lake bed our own.

       We topped off the charge on the bike’s battery and auxiliary starter battery in preparation for a warm up start. Fuel and oil levels were checked on the GR-7 before spooling up the turbine.

       After getting everyone their hearing protection I spooled up the engine to idle for a warm up cycle. The GR-7 didn’t let me down as it fired right up :0)

       I wasn’t able to pretest the afterburner at home due to the thunderous noise it makes so I needed to make sure it was working properly before the first run. I armed the afterburner and checked fuel flow by manually activating the pump at low speed.

       I raised the RPM to activate the AB ignition coil and POP..... POP..... GROWWLLLLLLL!!!! The afterburner came to life.

       The bright sunshine of the day hid most of the visible “fire show”. The afterburner was burning quite cleanly at full power making it difficult to see any evidence of ignition. Although you did not need to see the fire to know the burner was working :0) Andreas used his sound meter to check the Decibel levels at the side of the engine at full power. The meter showed about 117 db to the side of the AB duct. That is fairly loud but not nearly as loud as behind the engine.
       Of course we forgot to test the sound pressure behind the engine this trip but we will be sure to measure it next time.

       The next step was to scout out the course for ruts or debris with my shifter cart. I built this 250 cc cart many years ago and now it has a new purpose as a course pilot vehicle :0)

       I drove the course several times at about 65 MPH in the cart which helped me determine any problem areas. Luckily there was no need to move the course and testing could commence.

       After a short safety meeting with the crew I suited up for the first run of the day. I donned two pairs of jeans and military grade boots for added protection. I also had my jacket, helmet and heavy duty gloves.

       This time I was driven out to the start line with the Turbotug unlike my first speed trial event where I rode the bike to the start. My brother Mike was happy to pilot the Turbotug for me and get us out to the start line.

       Without hesitation the tug fired right up :0)

       And now the tug had to pull over 1000 pounds across the lake bed in 80+ degree weather. We put that little T3/T4 turbo through it’s paces!!!

       The tug pulled us along at about 25 MPH as it rolled out to the start line. Once again it amazed me that what we were riding on and what we were pulling was once just a series of unrelated parts and steel stock.

       Once we got to the start line we immediately unloaded the GRV-2.

       We connected up the auxiliary starter battery and spooled up the engine. My heart was racing at this moment as you can imagine.

       After getting the OK from the crew I fired up the afterburner and picked up my feet.

       This time felt quite different as I could really feel the thrust of the engine. The bike accelerated much faster than before and I was quickly making distance from the start line.

       My biggest concern at this point was that the bike would not go into a high speed wobble. I continually monitored the “feel” of the bike taking note of any instability.

       I was now approaching 50 MPH and all seemed smooth as silk. The wind was calm and the air was about 78° F which caused the lake bed to start to “mirage”.

       I could really feel the wind push against my helmet at this point. The bike was feeling stable with only a little side shifting which might of been caused by a slight cross wind. I could tell that I was going much faster than I had before as I approached the speed trap/finish line.

       I rocketed past the radar gun and pulled off the throttle. The brakes were applied and the bike slowed down. I could tell that their was a lot of stored energy in my speed as the brakes were heating up quickly. In fact the brakes would of been ineffective at an emergency stop at that speed. They only are able to slow me down at a gradual rate taking about 200 yards to completely stop :0P

Continued on next page

[Home] [What's New At RCDON] [Articles] [Aircraft Projects] [Aircraft Videos] [Aircraft Videos II] [Experimental Projects] [GR-1 Turbojet Engine Project] [GR-5 Turboshaft Engine Project] [GR-5A Turboshaft Engine] [GRV-1 Turbotug Project] [GR-7 Turbojet Engine Project] [GRV-2 Jet Bike Project] [GR Engine Series Q&A] [Readers Projects] [Experimental Projects II] [My Collection] [M.A.R.K.S. Club] [RC Links] [About Myself] [Contact RCDON]