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Karl and the Pulse Jet


Posted: June 22, 2014 6:00 a.m.
Updated: June 22, 2014 6:00 a.m.

Karl Mueller seemed as Germanic as his name; he had a very crisp manner of speech, a short-clipped flattop and impeccably neat clothes.

Above all, he was scientific. Not a wimpy, gazing through thick glasses scientific, but a bright, sparkling scientific.

Perhaps we went to grade school or junior high together, but we never knew it, because the time wasn’t right.

I’d guess it was during the spring of our junior year (1956) in high school that our destinies crossed.

It was brief, maybe two weeks, but now it glitters in my mind as a flashing meteorite.

The catalyst was a piece of pipe.

You see, I was scientific too. I was a devout scientific, and Karl’s pipe drew me into his orbit like the then-unknown black hole.

For perhaps three weeks, the pipe became our mutual passion.

Dynajet was its name. It was a small jet engine comprised of a pipe with a metal reed, similar to a clarinet, attached to one end.

If a battery was wired to its glow plug, and if young boys pumped vigorously on a tire pump, whose hose was jammed down its throat, and if model airplane fuel was dribbled in appropriate doses into the pipe, and if tongues were set at proper angles in the mouth, it would light.

The pipe would transform into a pulse jet engine with a roar that set dogs to barking for blocks.

It took two weeks to get it to light.

During Civics class, we would sketch designs for mounting brackets, and that afternoon we’d try to construct the thing on the workbench in Karl’s garage.

I cannibalized my old erector set (Mother was frosted), and thinking the pipe would get hot, we used hot pads “found” in Karl’s mother’s kitchen.

It took perhaps a week before we were ready for the first test.

I don’t think I’ve ever been so nervous as when we gassed the Dynajet for the first time. (This is an ironic thing when one is reminded that later in life, I made my living testing real rocket engines, big rocket engines!)

It lay there, lashed to the bench, looking sinister indeed.

We quickly completed our preparations. Karl swept aside the paint cans and filled the small gas tank while I positioned the tire pump.

We had composed an official-sounding checklist, thinking it would be more scientific, and I proceeded to intone the ritual.


“Filled,” Karl replied.

“Pump is ready. Glow plug on?”

Karl clipped on the wires. “On.”

“Here comes the juice.”

I removed the vise grip pliers from the plastic fuel tubing. “Gas dribblin’?”

Karl squinted into the pipe. “Yup. Pump it!”

I lunged like a maniac on the tire pump, blasting wheezy shots of air past the reed into the bowels of the pipe.

“More!” cried Karl.

I panted like a Saint Bernard in the Sahara as I heaved on the handle, but nothing happened.

“Abort,” declared Karl.

We sat cross-legged on the cold concrete floor and stared angrily at the defiant pipe.

“What do you think?”

“Don’t know.”

Soon the garage was filled with whispered scientifics. Diagnoses flowered forth and were followed by plans, then action.

About a week later, a vastly altered test setup brought life to the pipe.

The pipe, now sharply inclined, belched as I gave a superhuman thrust on the pump. Karl and I glanced at one another, his bright, straight teeth flashing.

“Again!” he growled.

Adrenaline surged into my bloodstream. “Go man,” I hissed under my breath.

“Burp!” said the engine.

Together, Karl and I chanted, “Go man, go man, go man!” as I hurled myself on the pump handle.

Burp, burrp, burrpppp, roarrrrrr!

Karl and I shrieked, whooped and slugged each other violently on the shoulder, as was the rage at the time.

The engine howled and grew a cherry-red mantle, which promptly set fire to the hot pad. Bright yellow flames leapt from the pipe and licked the legs of the wooden workbench.

In our ecstatic celebration, we failed to notice the pyrotechnic tendencies of our engine. No matter, a stunning silence filled the garage when the machine ran out of gas, leaving smoldering cloth and wood.

We simultaneously understood the gravity of the moment and ceased our childish hollering.

In the fog-like smoke, we faced one another and solemnly shook hands. Scientifics will prevail.

We started the engine a few more times, but once predictability had been established, interest waned.

I took no notice of the last time I walked from Karl’s garage. I took no notice that we rarely spoke after that. I took no notice that the time for Karl and I had ended.

Years later, at our 10-year high school reunion, I was glancing through the alumni directory listing addresses of classmates. My eyes flickered past Karl’s name, then settled back.

“Karl Mueller,” it said. “Deceased.”

There in the joyous cacophony of the party, eleven years after chanting “Go man” in exquisite harmony with Karl, I wept for him, a fellow scientific.


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