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Funfani.com - Spreading Fun All Over!IMAGE CORNERWallpapers/Cool ImagesCar PicturesCraziest Jet Powered Beetle
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Author Topic: Craziest Jet Powered Beetle  (Read 5453 times)
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Rhea Thomas
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« Reply #6 on: February 02, 2010, 03:19:20 AM »



The back of the gauge panel was kept open to give the car a techie look. Something to talk about. The car's an engineering device, let's see some engineering thingies. The aluminum panel was designed in SolidWorks and cut out of billet, bead blasted, clear annodized, and then the labels for the switches were milled into the front using a font matching the VW cluster. Little details like the holes having flat sides so the switches don't spin and exactly matching the contour of the dash added time to the project. Several versions were made out of styrofoam first to get the layout and lighting right. From the back, the panel reminds me of the 1970s McLaren CanAm cars.

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Rhea Thomas
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« Reply #7 on: February 02, 2010, 03:19:42 AM »



The first thing I did when I got the car was to cut the hole in the back for the engine. Made a fancy jig out of a tripod, a rod, and a lawnmower wheel to mark out the cut and went at it with a pneumatic saw. Then finished it off with jeweler's files. No paint required. Didn't even chip. The hole was tricky because it goes through 3 layers (bumper and two layers of metal) and it's a circle projected onto angled surfaces. Just finding the centerline of the car wasn't trivial. Worrying what my neighbors would say if I ruined the back of a brand-new car made me REAL careful. I believe the hole is within 2 mm.
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« Reply #8 on: February 02, 2010, 03:19:59 AM »



There are three gauges for the jet: %RPM, Oil Pressure, and Turbine Inlet Temperature. The most important is turbine inlet temperature. If you exceed about 650 degrees C for very long, you damage the engine. This is critical on start-up. You don't want a "hot-start". The throttle for the jet engine is located next to the gear selector. It is a lever and has three buttons: Cool, Big-Fire, and Afterburner. "Cool" leans out the engine and is used to lower the turbine inlet temperature if you get a hot-start. To light big-fire or the afterburner, you hold a button down and 1/2 second later, press the hot-streak button on the floor. Then things happen! Notice the kerosene level gauge in front of the gear selector (jet fuel is mostly kerosene) and the bud vase missing a rose. Where did it go?
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« Reply #9 on: February 02, 2010, 03:20:28 AM »



Lotsa stuff back here. The force from the jet is tied to the vehicle through sandwich plates inside the car bolted to contoured aluminum billets that were slid into the frame rails. You can see the billet on the left side with a hole in its center, welded to the plate with 4 bolts. Used helium as the inert gas and a lot of current to weld that chunk of aluminum. To return the car to its production height, adjustable spring perches were used. Same spring rate, just corrected the ride height. Drives and handles fine. Kerosene is stored in a custom 14 gallon, baffled, foam-filled kevlar fuel cell in the spare tire well. Two fuel exits in the back: a -12 on the left side and a -10 on the right. The -10 goes to a shutoff, then a Barry Grant pump (one of the few hot rod parts on the car), then up into the car where it sees a filter, a regulator, and an electrical shutoff valve before feeding the engine. The -12 goes into a shutoff, then a 1.5 hp, 11,000 rpm, 24V custom electric pump. Pump is magnesium and can maintain 100 psi at 550 gph. From the pump it goes into the car to a filter, then a large regulator, and then to the afterburner solenoid and the big-fire solenoid (to left of pump and feeding bottom of tailpipe through orange covered hose). Fuel system was tested for flow capability. Above the big pump you can see the relocated gasoline cap actuator and all that black stuff on the right side is the stock fuel evaporative control equipment. All circuits feeding solenoids and pumps have fuses, relays, kick-back diodes to minimize contact arcing, sealed connectors, and use automotive wires of a gauge giving a maximum of 1V drop over the circuit loop.
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« Reply #10 on: February 02, 2010, 03:20:44 AM »



The engine is a General Electric Model T58-8F. This is a helicopter turboshaft engine that was converted to a jet engine by some internal modifications and a custom tailpipe. The engine spins up to 26,000 RPM (idle is 13,000 RPM), draws air at 11,000 CFM, and is rated at 1350 hp. It weighs only 300 lbm. It grows as it warms up so the engine mounts have to account for this. The mounts in the front are rubber and the back are sliding mounts on rubber. The structure holding the engine was designed using finite element analysis and is redundant. Strong, damage tolerant, and light. Second battery and fuse/relay panel on the right, halon fire system and 5 gallon dry sump tank on left. 24V starter motor is in the nose of the engine. 700 A of current goes into that motor for 20 seconds during start-up. Due to heat, must limit starts to three in one hour. Big screen is to avoid FOD (foreign object damage). Jet keeps sucking the rose out of the bud vase on the dash!
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« Reply #11 on: February 02, 2010, 03:21:00 AM »



A lot of attention to details in the car. Note the aluminum block holding/protecting the halon gas line, pull line, harness to engine, and oil pressure line. Rectangular tank under inlet screen is for various fuel drains. Note temperature gauge and shutoff valve for dry sump tank. 3 gallons of turbine oil at $25/quart (ouch!). Two-stage PPG paint matching exterior of car was used inside the car. It is not easy to paint around a lot of bars, etc while crouched in a car, in your dusty home garage, avoiding drips, and with your wife screaming that the fumes will cause brain damage in the kids. Especially with two-stage where you have multiple coats and critical drying times. Kids passed their grades so I guess damage was minimal, but more importantly, the paint turned out great!

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« Last Edit: February 02, 2010, 03:23:53 AM by Rhea Thomas » Report to moderator   Logged
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