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The Fokker Universal is one of my favorite aircraft. There is only one complete representation of it in existence at a museum in Canada. A video series I saw on YouTube tells the story of its restoration and some of the history associated with it, and I found it all very interesting. But what confused me the most was the startup procedure. I know the engine is mainly started with an inertia starter, but I have no clue what the other crank in the cockpit is. If anyone has info, please help.

This first video is part of the video series I mentioned earlier. At 0:15, the crank I’m asking about is shown:

This second video shows the inertia crank on the outside of the aircraft. It shows up at 3:52:

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  • $\begingroup$ @PcMan -- that does seem likely. And if so, my answer is not really accurate-- the cranking is not really "engaging" the flywheel clutch, but rather is playing some other role in the starting. But why the need for the generator? Is the generator somehow "helping" the magnetos to generate spark? That's the most likely thing I can think of at this time-- $\endgroup$
    – quiet flyer
    Dec 13, 2021 at 18:37
  • $\begingroup$ @PcMan -- you should answer then-- you are welcome to borrow any portions of mine you wish; I anticipate I'll be deleting it eventually-- $\endgroup$
    – quiet flyer
    Dec 13, 2021 at 18:51
  • $\begingroup$ @PcMan (Some aircraft use an "impulse coupling" to give the magneto a faster motion and boost the spark that way during cranking; aircraft that use this method don't typically don't give the spark a boost from any other external source. And I don't believe that your typical 1950's-technology light plane with electric starter is tying the battery to the spark in any way. But I am sure you are right about that hand crank in the cockpit.) $\endgroup$
    – quiet flyer
    Dec 13, 2021 at 18:58
  • $\begingroup$ Thanks for posting these videos. I looked up the Universal in my copy of the 60-year memorial edition of Anthony Fokker, it mentions that there was a fully restored F.XI in Melbourne, owned by Ansett, in 1979, called Reginald Ansett's first Fokker Universal. $\endgroup$
    – Koyovis
    Dec 14, 2021 at 1:42

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It's being started with an electric inertia starter but the hand crank is not directly related; it's below the magneto switch and is part of the ignition system.

Before magneto impulse couplings that provided a decently strong retarded spark for starting, mags used a separate primary ignition circuit with its own retarded-timing ignition points, for starting only (the normal points operate with way too much advance for starting), which didn't run off the magneto's internal generator and had to be powered externally.

The most common system was called a vibrator, or "Shower of Sparks" (a trade name) ignition system, which used an oscillating current device that would send shots of current through the primary coil to generate a succession of sparks starting at about Top Dead Center of a cylinder when energized from the battery. When the engine was running, the starting circuit was simply inactive.

The system in the video is similar but runs off an independent Permanent Magnet Generator turned by the crank to make sparks that are suitably retarded.

So what you are seeing is the engine is cranking, the normal magneto circuit isn't really making any significant spark because it's spinning too slowly, but at the right time the little cranks is spun, which will supply sparks, through the separate primary starting circuit, to light off the engine, and as soon as it's running, the normal mag circuit takes over. That's why it cranks, but doesn't fire until the crank is spun.

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  • $\begingroup$ Yes but the question is what is going on in the cockpit at 0:24 to 0:27 in the first video? The pilot is rapidly turning a crank. It appears to be related to engaging the (already spun up) inertial starter, but why would this be accomplished by rapidly turning a crank? $\endgroup$
    – quiet flyer
    Dec 13, 2021 at 15:59
  • $\begingroup$ Yeah I didn't read it carefully, Rewritten as a new answer. $\endgroup$
    – John K
    Dec 13, 2021 at 19:17
  • $\begingroup$ At least some (all?) PT-13 Stearmans with 220HP Continental engines used for primary training in WW2 had such starters. I remember as a boy cranking them up after they came into civilian use after the war. After you had them wound up, you engaged the starter by pulling a T-shaped lever. $\endgroup$
    – Terry
    Dec 13, 2021 at 19:20

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