Robert Maddox stands next a giant pulse jet that he hopes when combined with 4 more will propel him to 25,000 feet in elevation. Maddox also plans to eject and parachute from the rocket. - Jamie Lusch

Sky's the limit for rocket builder

Bob Maddox has started building a rocket to take him to the stars.

Well, not quite the stars, but the Medford inventor hopes to shoot himself 25,000 feet into the atmosphere, jump out of the rocket and skydive down.

Maddox is an aficionado of pulse jet engines, which he makes in his shop on Griffin Creek Road. He has built the first of four 14-foot engines that he plans to mount around a rocket that will have a seat for him in the nose.

Maddox is a cabinet maker by trade, but when the recession dried up business he went back to his first love — tinkering with the pulse jet engines that first gained fame when Nazi Germany used them to send unmanned "buzz bombs" over London in World War II.

He's sold more than 100 of the engines on eBay, including several that power bicycles at speeds up to 100 mph.

Two big engines sit on the wingless Top Gun ground fighter owned by Wally Larson of Jacksonville.

Anyone who's interested in seeing the engines at work can go to YouTube and search for d14653.

The first thing you notice about a pulse jet is that it's incredibly loud. It also generates enough heat to make the big tail pipe red hot, which makes jet biking look incredibly dangerous.

After a decade of research, Maddox concluded there weren't a lot of practical applications for pulse jets beyond piloting a radio-controlled plane or a target drone. Then he thought, what about hitching them to a manned rocket?

Maddox said nobody had built and flown their own rocket before, and a "first" of anything can open a lot of doors, technologically.

The rocket he envisions will burn gas and kerosene, mixed with air drawn in through front baffles and ignited by flame blowing back from the exhaust. He will start it with an air compressor forcing air in the front.

Maddox envisions a rocket that will generate 4,000 pounds of thrust. It will start at a relatively low speed, 250 mph, so if anything bad happens, it won't happen quite so fast. Top velocity, though, will be close to supersonic.

The most dangerous moment for anything that flies is just getting off the ground. Maddox said his reserve parachute is designed to open, if he needs it, at an altitude of just 50 feet.

Steering a rocket that's climbing five miles into the atmosphere might sound a little tricky, but Maddox said he's making all parts using computer numeric code software, so they will all have identical performance. He'll monitor the engines with gyroscopes and servo mechanisms, which will nudge four small nose rockets for steering.

When he reaches an altitude of 25,000 feet, Maddox plans to go skydiving. A rocket in his ejection seat will fire for half a second, pushing him out of the rocket.

Skydiving from that height is the least of his problems. Maddox has parachuted more than 2,000 times, and he jumped from 20,000 feet in a mass jump of 100 people.

When he bails out, the engine will stop and a parachute on the rocket will deploy so that it can be recycled and used again.

Maddox figures he needs $40,000 to $50,000 to pull off his extreme adventure. Absent a money angel, he sees the cash coming from an extreme-sport TV show.

"It's about adventure," he said of his rocket plans. "It's for the entertainment value. It would make a great show or series on reality TV, like 'West Coast Choppers' or 'Monster Garage,' " he said.

Financing also could come from sponsors, who might be impressed that a story about Maddox in Wired magazine helped generate 600,000 visits for his video.

Maddox said he tries to consider every possible mishap as he builds the rocket.

"You've got to think of everything that could go wrong," he said. "You don't just hop in and hope it works."

He'll test an unmanned version first, but he has every intention of flying himself.

"I don't believe anyone has ever launched himself in a rocket," he said. "I know it sounds nutty. People look at me like I'm crazy, and I don't like that, but it would be a great TV show and I know I can make it happen."

John Darling is a freelance writer living in Ashland. E-mail him at

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