Over on the KP Publishing website (Flypast), there is a debate on Civil DC-2's purchased and shipped overseas for service in the RAF and other Commonwealth Air Forces, and in the midst of that discussion the issue of DC-2's fitted with larger fins and without nose mounted landing lights has arisen.
[url]http://forum.keypublishing.co.uk/showthread.php?p=1967303#post1967303[/url]
The DC-2 is well known for its narrow cord fin, and its nose mounted landing lights, which along with its flat sided fuselage are distinct and obvious differences of identification against the later DC-3.
Folklore has it that the wider fin, and relocation of the landing lights to the wing leading edges were just some of the many changes adopted into the DC-3 to meet the American Airlines order of the DST.
However it is clear the Military C39 adopted these two changes while retaining the narrow or flat sided DC-2 fuselage and it seems so too did some of the DC-2's delivered to American Airlines.
I was aware of some DC-2s having a larger fin (but not a full DC-3 fin with dorsal fin) but I wasnt aware of any moving the landing lights from the nose to the wing leading edges.
The fin enlargement related to control problems while the relocation of the landing lights related to glare back into the cockpit when landing in the rain.
Some googling identified that some later DC-2's delivered to American Airlines had the increased area fin fitted at their request, and I was aware of the larger DC-2 Fin, and while it is possible these also had the landing lights moved to the wing outer panels, I havent seen any specific textual reference to that, but it seems clear from photos that it did occur at some stage?
[url]http://www.flagshipdetroit.org/FSD/History-DC-3_files/LegacyofTheDC-3__FrankAtzert.pdf[/url]
[quote]One of our initial experiences with the DC-2 demonstrated an additional shortcoming, that being the discovery that it needed increased vertical fin area. This came about on a blustery day in Chicago, when American's Chief Engineering Test Pilot, M.G. "Dan" Beard, was checking out a line Captain. The final exercise in their program was a go-around with the left engine idling. At about 500 feet, extremely rough air was encountered at a time
when Beard's attention was distracted by a rising cylinder head temperature on the right engine. Sensing a force throwing him to the right, he looked up and found the nose high and turning to the left. He then glanced down to see the Captain's foot pushing fully forward on the left rudder pedal. His panel scan spotted an airspeed reading of about 72 mph. Recognizing that the airplane was going into a flat spin, Beard recalled that during flight testing one DC-2 lost 5,000 feet in a similar situation before control was regained.
He shouted for rudder trim while he slammed throttles wide open, shoved the nose down, and pushed in full right rudder. Though Beard knew full throttle would produce excessive manifold pressure at their low altitude, he also knew that nothing less would produce the airspeed needed to overcome their predicament: a fin stall. Fortunately, the airplane staggered out of its stall, and it was later discovered that this condition consistently occurred right at 72 mph. American's engineers held immediate discussions with engineers at Douglas that resulted in a fin extension of sufficient area to lower the fin's
stall speed by 4 mph. All DC-2s received by American were so modified.[/quote]
Its not clear when that decision was made, as most photos of American Airlines DC-2's do not exhibit an obviously larger fin, so the question is when was that implemented?
American Airlines purchased DC-2's under the -120 customer number with their first order for 10 beggining with s/n 1307 NC14274 in November 1934, and finishing with s/n 1316 NC 14283 in December 1934.
They had a second order of 8 DC2-120 aircraft commencing with s/n 1401 NC14921 in May 1935 and finishing with s/n 1411 NC 14925 in August 1935 but interspersed with other customer deliveries in the block.
The standard DC-2 fin has some distinct features that are obvious against the wider fin.
These are,
1. the hinge line between the fin and the rudder is vertical at the top (the wider fin extends over the top of the rudder as per a DC-3).
2. The leading edge of the fin alligns with the leading edge of the horizontal stabilisers in terms of the fuselage mating point (the wider fin extends much further forward along the fuselage than the standard fin).
This photo from Time Magazine of two DC-2s clearly shows those two obvious differences and the aircraft with the larger fin is in my view confirms the Delta Airlines DC-2 120 has the standard fin.
[img]http://www.gstatic.com/hostedimg/875359a838e378d0_landing[/img]
The photo above gives a general appreciation of the differences but the source photo can be enlarged on the website below to allow detailed examination of the differences.
[url]http://images.google.com/hosted/life/875359a838e378d0.html[/url]
The aircraft with the wider fin is from the second batch of DC-2s ordered by American Airlines, and is likely to incorporate the wider fin as specified by them following the experience of the fin stall referred to in the above extract.
It seems s/n 1406 was built in October 1935 as NC14966 for American Airlines, (and its likely that it therefore had the larger fin), but was apparantly re-designated a C32-A and as 42-58073 before sale to the British Purchasing Commission in April 1941 and then later served with the RAF as AX768 with 117 Sqn in Karthoum.
I havent compared the wider fin to the DC-3 to a great degree, but it is effectively of a similar form to the DC-3 but without the dorsal fin extension.
I do suspect however that this wider DC-2 fin is the one specified by American Airlines to overcome the fin stall referred to above, and therefore suspect it was specified on all 8 of the aircraft in their second order, however so far I have only found one photo of an aircraft from that batch, and all of the photos of aircraft from the first batch of 10 clearly have the standard or narrow fin in my opinion.
At this stage its my suspicions that the first order of 10 American Airlines DC-2 120 aircraft had standard fins and either factory fitted or field modified wing mounted landing lights, while the second order of 8 American Airlines DC-2 120 aircraft had the wider fins and factory fitted wing mounted landing lights.
I consider these were largely limited to American Airlines orders as they are both not reflected in photos of any other ordered or operated civil DC-2's.
Given American Airlines close involvement in the specification and development of the DST/DC-3 it is possible we have stumbled onto some earlier company specific developments of the DC-2 series.
The only way this can really be resolved is either through the archival records of American Airlines or Douglas?, and hopefully somewhere there might be Douglas production line records or photos, and American Airlines delivery photos of these 18 aircraft to confirm these issues?
There are a few specialist books on the DC-2 (which I do not have) and its possible these issues have been identified and documented in one of those?, and so I thought this issue was worth posting on a few other civil airliner forums to enquire?
Here is a production list of DC-2s identifying the two seperate blocks of DC-2s ordered by American Airlines.
[url]http://www.wimparmentier.nl/produktielijst_dc2.html[/url]
Here is a list of the American Airlines Propliner fleets which lists a total of 15 DC-2's flying with American Airlines and interestingly refers to them as DC-2/C32 aircraft?
[url]http://www.prop-liners.com/aafleet.htm[/url]
It is missing s/n 1411 and 1412 which may have been sold on before delivery?
Here is a picture of an American Airlines DC-2 NC 14278 (4th example delivered to AA) with apparant landing lights on the wing leading edges and the small fin? (which doesnt prove the landing lights have been deleted from the nose as against additional ones fitted to the wing leading edges)
[img]http://www.edcoatescollection.com/ac3/Airline/American%20DC-2.jpg[/img]
NC14278 is a DC2-120 s/n 1311 delivered December 1934.
Here's another photo of it.
[img]http://www.stinsonflyer.com/prop/dc2-01.jpg[/img]
Here's NC14275, a DC2-120 s/n 1308 built for American Airlines in November 1934 (2nd DC-2 delivered to AA) but later sold on to Delta Airlines, it was also sold to the BPC for RAF service as DG473. Note it has the small fin, and landing lights on the wing leading edges, and apparantly no landing lights on the nose.
[img]http://www.stinsonflyer.com/prop/dc2-02c.jpg[/img]
Even more interesting is this film on youtube (about 4 minutes into the film) of an American Airlines DC-2 14283 with the small fin, and landing lights on the wing leading edges and no landing lights on the nose! (this is the last of 10 delivered to AA in the first order).
[url]http://www.youtube.com/watch?v=T_Vt7DVglw8[/url]
NC14283 is a DC2-120 s/n 1316 delivered December 1934.
So from the above, it does seem to me that American Airlines ordered some DC-2 aircraft with the larger fin, most likely the second order? as all of the first order appear to have the standard DC-2 fin?
It would also seem American Airlines DC-2 aircraft, including those from the first order had moved their landing lights from the nose to the wing leading edges either in the ordering of their first series of DC2-120 aircraft, or retrofitted them in the field?
Still confusing yet these modifications do still seem to be a practice limited to American Airlines either by factory order or field modification?
So the challenge then is to try and find a photo of one of those first 10 original American Airlines DC-2's with nose landing lights fitted! to confirm it was a field modification by American Airlines, or to find some factory or Airline archival records of this being a landing light design change in the first order.
So is there a DC-2 Expert in the house?
Regards
Mark Pilkington |
