Chipmunk Mk.23
Regarding the rather more elegant SA29, I think the endless bickering between AeroStructures/Mike Sassin and DCA which greatly delayed certifying this aircraft effectively killed off the potential market - only three were ever built (oddly two still survive, though not in the Spraymaster form). The Sundowner never even got off the ground (literally) - DCA wouldn't certify this, the "VH-CXZ" registration is spurious.
I've seen pictures of the Mk 23 before, but it was only after looking at Dave Unwin's spectacular picture of the Bumblemunk, that I began to wonder about C of G issues. The T10 Pilot's Notes specify that solo flight is restricted to the front cockpit. How is the C of G handled in the Mk 23?
I42:
I was told that one reason that the conversion of the SA29 back to the DHC-1 configuration (the VH-BCA project) was "easy" was because the pilot's seat was in the same position as the rear seat in the Chipmunk (only mounted higher), whereas the Mk.23 seat was located more between the original seat positions meaning that the centre section would have to be re-worked in order to re-converrt.
Re your "solo from the front seat" comment, I'm unsure if there is a balance reason why this should be so. The front seat is located directly on the datum point, meaning that the front seat occupant generates a zero moment arm. Therefore, by my admittedly possibly dodgy logic, the CoG position with two occupants or one only occupant in the rear seat should be the same. And no, I've never tried this out!
I was told that one reason that the conversion of the SA29 back to the DHC-1 configuration (the VH-BCA project) was "easy" was because the pilot's seat was in the same position as the rear seat in the Chipmunk (only mounted higher), whereas the Mk.23 seat was located more between the original seat positions meaning that the centre section would have to be re-worked in order to re-converrt.
Re your "solo from the front seat" comment, I'm unsure if there is a balance reason why this should be so. The front seat is located directly on the datum point, meaning that the front seat occupant generates a zero moment arm. Therefore, by my admittedly possibly dodgy logic, the CoG position with two occupants or one only occupant in the rear seat should be the same. And no, I've never tried this out!
This might help explain. Note that the certified CoG range has changed from when this was published.
Last edited by Dora-9; 30th Jan 2020 at 17:32.
Mike Sasin the engineer responsible for the SA29 design/modification ended up working for Australian Air Charters at Moorabbin Airport in Melbourne. I was employed by the same company during the mid seventies and knew Mike quite well. He was a nice bloke but terribly bitter about his fight with the 'Department of Changing Names'. (I think it began under DCA). One of the stumbling blocks, if I remember correctly, was the seat belt attachment fittings. Just mentioning it, poor old Mike would go into orbit.
The man must have been a saint George - not only the ongoing squabbles with the "Department of Changing Names", which at one stage involved importing a second fuselage to repeat the conversion to their satisfaction, but when he witnessed the first Spraymaster have an engine failure on take off and crash THE DAY AFTER IT WAS PLACED ON THE REGISTER he helped drag the pilot from the wreckage. Given that the engine stopped due to fuel mismanagement, I've have pushed him back in!
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[QUOTE=Dora-9;10674782]I42:
I was told that one reason that the conversion of the SA29 back to the DHC-1 configuration (the VH-BCA project) was "easy" was because the pilot's seat was in the same position as the rear seat in the Chipmunk (only mounted higher), whereas the Mk.23 seat was located more between the original seat positions meaning that the centre section would have to be re-worked in order to re-convert.
Hi Dora, that's very interesting! I'll investigate that but suspect that the rear cockpit is essentially the same. I was flying TF recently and the seat is about abeam the trailing edge, as per the back seat in a T.10 (see pic)
. Also, simply keeping the rear cockpit would've made the Mk.23 conversion much simpler.
I was told that one reason that the conversion of the SA29 back to the DHC-1 configuration (the VH-BCA project) was "easy" was because the pilot's seat was in the same position as the rear seat in the Chipmunk (only mounted higher), whereas the Mk.23 seat was located more between the original seat positions meaning that the centre section would have to be re-worked in order to re-convert.
Hi Dora, that's very interesting! I'll investigate that but suspect that the rear cockpit is essentially the same. I was flying TF recently and the seat is about abeam the trailing edge, as per the back seat in a T.10 (see pic)
. Also, simply keeping the rear cockpit would've made the Mk.23 conversion much simpler.
Dave, my engineering knowledge comfortably fits on a pinhead, but that's what the gents at Mareeba (who converted VH-BCA back to the DHC-1 configuration) told me. I too have looked at that Mk.23 photo and pondered...
I'm certainly open to a correction on this.
I'm certainly open to a correction on this.
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Hi Dave, I have no pics but have fond memories of getting towed behind her on many occasions when gliding with the RAFGSA at Bicester between November 1972 to October 1974. She still had a Gypsy engine then. Great to see her still flying.
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Thanks Treaders, and here's a fine Keith Wilson photo of Chipmunk Mk.23 'BumbleMunk' flown by me near Saltby Airfield. Can't say too much more, but look in WHS next month....
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Another fine Keith Wilson photo of Chipmunk Mk.23 'BumbleMunk' flown by me near Saltby Airfield. Can't say too much more for obvious reasons, but a full report on flying this rare Chipmunk will appear in a popular magazine very soon ...
I do wish the late/great Dick Stratton was still around to answer the queries on Tango Fox, he would have entranced you for hours.
Last edited by Dan Winterland; 28th Mar 2020 at 08:46.
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Hi Dan, according to my research WB563 was bought by Farm Aviation Ltd in 1963, registered G-AOTF and converted to Mk.23 configuration. By 1967 ‘Tango Fox’ had left the agricultural industry and flew as a glider tug with Air Tows at Lasham. It then joined the RAF GSA (again as a tug) and eventually had its original Gypsy engine replaced with a Lycoming O-360. That is a terrible paint scheme for a tug!! BTW I met Dick a couple of times when I was the BMGC Tug Master and he the BGA CTO - very interesting bloke, extremely pragmatic engineer.
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You might want to get in touch with some former Clevelands ( RIP ) people when we operated it at Dishforth. .....been dragged into the air many times by her.
Also met Dick Stratton a few times ..had an "interesting " test flight with him out of Bicester once in "CX " also from Dishforth. Brilliant guy and source of information.
Also met Dick Stratton a few times ..had an "interesting " test flight with him out of Bicester once in "CX " also from Dishforth. Brilliant guy and source of information.
