Interesting Dutch News Video Site

[NickLappos]

Here is a page with a few great videos of older helicopter operations in Holland, including a good look at the Kolibrie, a tip-jet helo that was fully certified. In the clip, it is being flown by Rene Van Der Harten, a great Dutch pilot, and one of the founders of KLM Noordzee. I had the honor to fly with Rene back in the old days when they bought their first S-58T's.


http://geschiedenis.vpro.nl/artikelen/16369422/

[Graviman]

Got vids to work, and well worth it too! Rene Van Der Harten, seemed to be enjoying himself in the Kolibri. My dutch is not good, but 1 hour endurance and 120km/hr shows how inefficient ram jet tips are. Notice the 4 fuel tanks under the rear fuselage. Tail rotor was only there for yaw control, but's it's interesting that a rudder was rejected in favour of tail rotor drivetrain. Control looks very good too, although there are no moving parts in the tip jets to adversely affect it. I notice hub was direct control, with cyclic hanging down from hub (through inversion mech?) and a seperate mechanism for collective pitch.

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Nick, have you ever flown any direct cyclic hub control helicopters, like the Kolibri? My suspicion is that direct control of hub angle gives a much easier machine to hover. I tried to get some feedback on the autogyro thread a while back, but no joy. I'm hoping a former TP can give a dumb engineer better flight test data! :}


Mart

[NickLappos]

Mart,
I think the Kolibrie failed because it was so very fuel inefficient, mostly because ram-jets are the best way to turn fuel into noise unless operated at Mach 3 or so. Thus, the machine was expensive to run, and even at 1960 fuel prices was not cheap enough to buy to offset the fuel costs. Today, it would be a really bad bet, I think. Nonetheless, it is a great data point on how to make a mechanically simple system.