Armstrong Starters and Other Old Things

Ah, the days of old when men were bold and planes had round engines… And no electric starter. I got to fly with, and learn from, men and women of the Olde School, and they had more rituals than the Eastern Orthodox Church when it came to starting airplanes. Once I started working on vintage beasts, I learned why.

Round motors are sweet, amazing pieces of art and power when they work as desired. They are stone cold [invective of choice] when they don’t. And starting them is not as easy as the modern prime with gas, turn on magnetos, hit starter, add throttle and go. Oh no, no, one treated radial engines with the same delicate manners and techniques used for… Never mind, PG-13 blog. Anyway, crank and go is not a radial engine “thing.”

This is due in part to the basic design of radial engines. The cylinders are arranged in a circle around the crank-case, with the crank shaft and propeller shaft running through the center. Turbo-chargers and accessories are mounted behind and (often but not always) above the engine, or around the back. The oil drains out the bottom when you need to change it.

An unnaturally clean, 14-cylinder German engine. Note the two rows of seven cylinders. Fair Use under Creative Commons 4.0. From Flicker.  

The first thing one does before starting a radial engine is rotate the propeller through by hand or using a very low-powered vehicle, IF the plane does not have an oil scavenging system, or you don’t trust said system. First, make darn certain that the ignition system is off, that the fuel is turned off, and that you are in a place where you will not get pulled into the propeller if it decides to “turn over” under its own power. Turn the prop through at least two full rotations. You want to make certain that no oil has accumulated in the bottom cylinders. Otherwise, when you add starter power to the engine, the piston will attempt to compress the oil instead of the gas vapors. This is known as hydraulic lock, and bends pistons, and can break the cylinder clean off the case. Mechanics and crew chiefs do not like this. Neither does the engine.

However, there was a time between the beginning of the large radial engine age and the perfection [waits for knowing laughter to stop] of the electric starter. This was the Age of the Inertial Starter, better known as the Armstrong Starter. No, not because of the name of the inventor. Nope, because of what it took to crank the starter hard enough to store sufficient energy to turn the engine and begin the ignition sequence.

Yes. Crank the starter. By hand, often while perched on the leading edge of the wing while the pilot did the two-handed starting ballet with switches and levers (throttle and mixture control) and stood on the brakes. Should a volunteer or other suitable victim not be found, the pilot adjusted things just so in the cockpit, set the brakes, made sure of the chocks, cranked the starter, then either ran around and climbed back in or leaned into the cockpit and started the engine, then ran around removing the chocks, jumped back in, stood on the brakes, and fastened his shoulder harness. Things went a bit more calmly after that. If it all worked. If the engine didn’t back-fire. If the brakes didn’t slip. If the chocks holding the wheels still did their job. If the engine didn’t decide to quit because the fuel-air mixture had gotten a little lean because the lever slipped, if…

Ah, the days of old, when men were bold, and engines a lot crankier than they are today. Although any piston engine needs some care when starting, and it is really easy to toast turbo-prop engines (and their starters) if you are not paying attention.


27 thoughts on “Armstrong Starters and Other Old Things

  1. The “Armstrong” rotator for antennas had the addition confusion that Edwin Armstrong invented damn near half of radio, it sometimes seems.

  2. A friend built a replica* of the Wright Model B upright 4 cylinder engine for the Hiller Museum in San Carlos, CA. It was for the replica Wright “Vin Fiz” they did in the 90s. When the engine was complete, he brought it to the model(!) engine club and we started it with a test club (no thrust, just paddles). My only experience with an inertial starter; and that was under ideal conditions to start.

    (*) Said friend (lost touch) liked to build largish scale models of really large engines, but this was a 1:1 model from original drawings. One set he acquired was from Denmark.

    • I am a member of the Bay Area Engine Modelers club. There is video of the one of John Palmer’s Wright Brothers engines running — .

      Unfortunately, I should also let you know that Mr. Palmer has moved on to where he can discuss experiences with the Wrights.

  3. One origin I’ve heard of the english surname “Armstrong” was a medieval Knight Sir John (or other christian name of your choice) of the Strong Arm. Appropriate for starters and some automotive steering systems.

  4. My shoulder is saying “NO!!”, and that’s only from de-tensioning the spring on a lawn tractor attachment. Could be a lot longer to turn this one up, and go full Arm Wrong.

  5. There is a depiction of a hand starter of an airplane in the movie “The Great Escape,” when the Scrounger and the Forger (James Garner and Donald Pleasence) steal a plane from a Luftwaffe airbase, though it is an inline engine rather than a radial.

  6. In between the Armstrong and electric methods was the Coffman starter, which used gunpowder. I don’t know if any aircraft ever used compressed air starters, but those were once popular wth Diesel engines.

    • I wonder if it is possible to design a fantasy world tech base such that a more high explosive based starter seems desirable, or even lasts long in service.

      If I wrote one, I wonder how long it would be before someone wrote in with credible proof that I have overlooked a simple, feasible alternative, equally justifiable in the described tech base.

      • In print? Two weeks. On the net? Probably an hour after the book went live. *rueful grin* Granted, I was dealing with people who do water law and argue for a living…

    • A cartridge starter was a key part of the plot of the 1965 film “Flight of the Phoenix”.

      The B-52 has a cartridge start on one jet engine as well, or at least it used to.

    • The Soviets used compressed air starters on some of their radial engines (and maybe others). Apparently they are a lot more reliable than cold-soaked batteries and electric starters in the Russian winters.

  7. Heh… probably the most POLITE post I’ve ever seen about starting Radials… 🙂 And yes hydraulic lock DOES have some very negative consequences… grumble…

  8. It looks like the picture is of a model radial engine (glow plugs, and the header connections say “model” not full sized). Any idea who manufactured it? At least in the 1990s, 5 cylinder models were available from OS Engines and Saito. Plans are available for more ambitious engines, including an 18 cylinder (Wright Cyclone?), and the Bentley BR? rotary from late WW1. It looks like some tiny vendors are doing some of the more complicated engines.

    (Rotaries are interesting; stationary crank shaft, and the cylinders spin. Heavy gyroscopic effects are purely coincidental. /sarc )

    • “Heavy gyroscopic effects are purely coincidental. /sarc ” Hey, it’s a feature, not a bug. Despite the numbers of newly minted pilot officers killed on takeoff in aircraft like the Sopwith Camel, the manufacturers and brass continued to tout the “maneuverability” of the planes.

      • Zlin and other European-made aerobatic aircraft have engines that are backwards to US engines. “Left rudder! Left rudder!” Apparently you don’t want to be too close to the runway when someone tries one out solo for the first time. Almost as exciting as watching someone land a Pitts for the first time.

  9. I recall reading something about the care and feeding of radial engines in, of all places, Shattered Sword, a book about the Japanese side of the Battle of Midway. Carrier aircraft of that time virtually all used radial engines because they made for a more compact powerplant than in-line engines. Warming up those engines had to be done slowly and carefully – at least fifteen minutes, and could take longer in cold weather. Apparently the engines had a disturbing tendency to choke or die or fail in other novel and interesting ways if you demanded full power from them when they were cold, and carrier takeoffs of course require full power.

    • Radial engines also didn’t require a radiator. Leaky radiator, miles and miles of ocean…yeah, I’d stick with radial too.

    • It is also, although not always, easier to get to the parts of a radial engine for repair. I have heard nothing good about the Merlin engine from people who “get” to work on them. Reaching the accessories is… sporting.

  10. Some models of the M-4 Sherman tank had radials, and required 60 revs before starting!

    • …then there was Chrysler, which arranged five flathead six cylinder car engines into a Goldbergian monstrosity called the A57 Multibank, which powered, among other things, Sherman tanks.

      Engine mechanics, seeing an A57 down in its steel hole though the service hatch, surely thought they had seen a vision of Hell… not like a radial engined aircraft, which was a marvel of simplicity and easy access by comparison.

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