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Post by DragonflyDH90 on Jun 14, 2014 21:14:59 GMT 12
Nice video Richard. Thanks to you and John for bringing it down, great machine.
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Post by brendanodell on Jun 18, 2014 15:25:42 GMT 12
Is it back-firing in that first pic? They are lovely pictures of the old girl. Incidentally - it's not backfiring that has been captured on the photograph showing a lick of flame from the Dak's exhaust tail pipe - but rather an oft seen, but little spoken of (or rather explained) feature of the R-1830 and R-2000 engines. Without getting into a long-winded explanation of manifold pressure vs RPM at part throttle, the R-1830 is equipped with an accelerator pump, mounted on the carburetor base, which provides a spritz of fuel during rapid throttle opening, directly into the supercharger (or blower) throat. What happens to create the visible lick of flame on rapid throttle closing action (such as closing the throttle on landing) is the following (to quote from Pratt & Whitney Engine Operation Information Letter # 22, dated April 20th 1951); ".....The essential factors involved in producing manifold pressure (P3) are carburetor deck pressure (P1), supercharger entrance or blower throat pressure (P2) and the supercharger compression ratio (C.R.)............An interesting side result of this phenomena occurs on certain engines equipped with accelerating pumps that are actuated when the blower throat pressure increases. The Pratt & Whitney Aircraft Twin Wasp C and D (R-1830 and R-2000) have this feature. The theory of this arrangement is that when the throttle is opened for more power the increase in P2 acts on a diagphram which causes additional fuel to be discharged. This accelerator device only knows that P2 is increasing and does not worry about why it increases. When the throttle is closed, as during a landing, and the RPM decreases rapidly, P2 is released from the cylinder pumping action and increases rapidly toward P1. This is the signal that the accelerator has been
trained to watch for and it goes to work squirting in more fuel at a
time when less is preferred. As a result, torching may occur." |
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Post by Gavin Conroy on Jun 18, 2014 19:11:32 GMT 12
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Post by Dave Homewood on Jun 18, 2014 23:30:47 GMT 12
Wow!! Those are stunning shots Gavin. Literally for the first time, I had the thought go through my head "I wish I'd been there now", on seeing these.
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Post by Gavin Conroy on Jun 19, 2014 7:00:06 GMT 12
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Post by flyjoe180 on Jun 20, 2014 11:09:04 GMT 12
Incredible images Gavin, nicely done.
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Post by Dave Homewood on Jun 20, 2014 11:39:56 GMT 12
These photos are way better than the ones they used in your spread in Classic Wings (good as they are in that article). We're very privileged to see these, thanks Gavin!
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Post by skyhawkdon on Jun 20, 2014 16:53:35 GMT 12
I agree - they are stunning photos Gavin.
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Post by beagle on Jun 20, 2014 18:31:18 GMT 12
he's a pretty good shot hey. pretty heavy prop vortices.
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Post by Gavin Conroy on Jun 20, 2014 20:10:49 GMT 12
Will posts a few more once I have seen the Wanaka book. I have all the file numbers here but would rather post what they don't print. Was too buggered after the show each day to go out for a few beers etc must have worked hard, was nice to get home after six days on the airfield!   |
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Post by beagle on Jun 20, 2014 20:48:44 GMT 12
well that has made my nite, another herk image.
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Post by Dave Homewood on Jun 21, 2014 0:15:18 GMT 12
And it's one of those special Slinky Hercs too!  |
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Post by beagle on Jun 21, 2014 5:29:27 GMT 12
special slinky herks ?
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Post by Dave Homewood on Jun 21, 2014 13:21:11 GMT 12
It's got the slinky-like vortices going on. You know, those spring toy things....
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Post by beagle on Jun 21, 2014 14:43:50 GMT 12
no
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Post by kiwithrottlejockey on Jun 27, 2014 15:15:33 GMT 12
The official DVD and book for Warbirds Over Wanaka 2014 turned up in my PO Box this morning.
Now if only the folks from Classic Fighters could pull finger and finish the official Classic Fighters 2013 DVD and get it out.
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Post by Gavin Conroy on Jun 29, 2014 14:04:10 GMT 12
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Post by Mustang51 on Jun 30, 2014 8:00:54 GMT 12
Folks, I think that you will find that the Omaka troops have been very busy on the DVD and, yes it is perhaps 'late', but in the global scheme of things, one must wait for all really great things ! It really does take some time to put something like that together especially when also planning and executing a Royal visit. GMO must have been beyone the Plimsoll for the last several months. Lots of good footage of that visit on this side of the ditch. Gavin....... I could not see the shots but I knoew that they would have been great. Are you heading to Duxford to give us wee mortals some coverage there?
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Post by Mustang51 on Jun 30, 2014 8:02:49 GMT 12
Dave.......... can you put spell check on this or maybe it is just my "legs of lamb" fingers......
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Post by flyinkiwi on Jun 30, 2014 9:53:36 GMT 12
Gavin, your photos are excellent as always, but from someone who was there, the constantly changing light conditions made photography extremely challenging, and your gorgeous photos stand as testament to your skill and patience. I salute you sir.
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