Smithy’s “afterburning” turbine powered ¼ scale jet dragster.
The idea of a turbine powered jet dragster occurred to me a few years ago, as a sideline “hobby” I also crew for a Top fuel Dragster and several Jet dragsters around the country. As I watched the jets go down the track I thought to myself…. ”I can possibly make a scale model of one of those”. Aside from my day to day job of “turbine fuel systems technician”, I also dabble in miniature turbine engines mainly for the model aircraft industry. This meant I had access to miniature jet engines of various sizes…I did some very quick calculations and found an engine to base a jet dragster around.
My first attempt at a scale jet dragster was a fairly shabbily built 20lb thrust 1/5 scale machine, I mainly built it to determine whether it would be feasable to build a larger ¼ scale machine….strangely enough the 1/5 scale car actually worked well enough to give me some insight and incentive to go ahead and build a ¼ scale jet dragster….And hence “Christine” lives, (based on the 1983 movie of the evil possesed 1955 “Plymouth Fury”), my wife’s name also happens to be Christine, a coincidence….hardly!
I started to build the ¼ scale car about mid January 2010, the first firing of the car was mid March 2010, so a build time of around 8 weeks. A few things needed “tweaking” but essentially it was a goer. I had quite a few problems getting the afterburner to light-off and sustain a good flame at any rpm setting. After a few weeks of “experimental” work on the exhaust can, fuel spray ring, hot streak system and flame holder I managed to get a fairly decent flame….unfortunately these components take quite a battering within the exhaust and often require replacement due to excessive heat and shock, after the first replacement was made the unit didn’t quite work the same…..more experiments and/or testing was required.
As the months wore on I found a happy medium with the parts and the system seemed to work reasonably well and some “track testing” was next on the agenda. As another sideline, I maintain the Westinghouse J-34 powered jet track dryer at my local drag strip….and thanks to the kind management at the track this allows me the freedom to run my car up the track every so often, this doesn’t happen very frequently but I hope to change this. I’ve only been able to run the car up the track a few times so far and hope to do many more in the coming months.
As of this writing the highest speed the car has attained is ~146.40 mph (~235kmh) however I wasn’t able to back this up with a second run within 1%. My official “backed up” highest speed is 126.43mph (203.56kmh) which was done on the afternoon of Wednesday April 7th 2010, the same day as my 146mph run.
Later this year, (Nov 2010), I will be travelling to Queensland (Australia) to attend our first annual RC speed challenge. Hopefully this event will see many new Australian records achieved by many people in the many classes available.
Owner/Builder/Driver: Brett Smith
Location: Sydney, Australia.
Car: Scratch built jet dragster, aluminium chassis with 75" wheelbase.
Weight: 12.75kgs fully fueled and ready to run.
Engine: Custom built 30lb thrust turbine, Auto-electric start, single stage centrifugal impeller turbojet with a 70mm cast inconel 713c turbine wheel.
Afterburner: Custom built afterburner unit of inconel 625 and 316 stainless utilizing 3/16" 316 stainless tubing for spray ring and a custom design flame-holder.
Fuel system: Two fuel tanks, 1x1200ml (afterburner) and 1x 800ml (engine), with dual fuel pumps with combined consumption of <1.5L/M
Engine Control Unit: Fuzzy-logic ECU with EGT, RPM and Throttle position input.
Radio: HiTec Aurora 9 Tx with Optima 9 channel Rx
Servos: 4x Hitec 25kg digital metal gear.
Wheels: Front two 140mm solid scooter wheels. Rear: FG monster truck wheels with slicks.
Brakes: Twin rear wheel servo/cable operated disc brakes and twin 30" cross-form parachutes servo actuated.
Body: Mike Casey (US) 1/4 scale Top Fuel full fibreglass.
Current varified top speed: 203.56kmh (126mph). 233kmh (145mph) has been clocked but as yet not backed up.
SureFlow Exhaust Sytems, Australia.
Hobby's R Us, Sydney.
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