The pylon on the inboard wing was perpendicular, i.e. hanging straight down (except on the unique pylon for the big podded radar: see http://tailhooktopics.blogspot.com/2012/11/ad-4n-aps-31-radar-pod.html). The pylons on the outboard wing panel were perpendicular to the wing instead; they were also not evenly spaced.
The outboard wing pylons were also not "swept" at the same angle as the leading edge, i.e. the most outboard one was closer to the wing leading edge than the most inboard.
The external center-line pylon was introduced with the AD-4B and carried forward to the AD-5/6/7:
Note the interface with the oil cooler outlet: the forward end of the pylon is much deeper because it sweeps up into the duct (don't be mislead by the shadow).
Early ADs had much smaller and less capable AERO pylons on the outboard wing panel. See http://tailhooktopics.blogspot.com/2013/12/things-under-wings-aero-pylons.html
AD-1s through -4s had a smaller inboard wing pylon than the 5/6/7. The later, longer pylon introduced on the -5 was reportedly necessary to move certain stores farther forward for ground clearance. It also added provisions for the 30-inch lug spacing required for some stores. In addition, it may have been desirable to move the loaded center of gravity forward, particularly on the -5.
Here is a direct comparison of the World War II era 1,000 and 2,000 lb bombs on the earlier pylon (note that the 2,000-lb bomb had 30-in lugs and therefore had to be attached with an adapter).
As noted above, ADs before the -4B/5/6/7 did not have an external center pylon. The shackle was mounted within the fuselage along with provisions for an explosive-cartridge actuated "foot" that propelled the bomb downward away from the airplane when dive bombing so that it would not hit the propeller.
Illustration from Ed Barthelmes
U.S. Navy via Steve Ginter
Hi, I'm currently making a model of an AD-3 Korean War era. I've seen some photos that show the centre-line pylon absent and instead the bomb attached straight on to the fuselage. Can you confirm if this is true, thanks in advance.
ReplyDeleteOops - missed that difference. On the early ADs, the center shackle was mounted in the fuselage so the bomb was snugged up against the belly. See the added detail provided in the post.
ReplyDeleteThanks for that, much appreciated.
DeleteFrom David Collier, with respect to what I call the centerline rack: "We called them, ejector rack or Douglas bomb ejector, never centerline rack. Our AD-4s had the rack as shown in the pictures which could only carry bombs with 14” space between lugs. Our AD-5Ns (Which were brand new when we received them in 1955) had the ejector rack modified to have suspension hooks spaced at 14” and 30”. The larger spacing was used for nuclear stores and the large streamlined tanks. The AD-4Bs that we had had the same bomb ejector as the AD-5N but without the streamlined fairing.
ReplyDeleteOur AD’s never carried any nuclear shapes. We never loaded a 2000 pound bomb or low drag fuel tank on the center rack, only on the Mk-51 wing racks. We never fired a bomb ejector cartridge because the ejector had to dissembled and cleaned if a cartridge was fired. All tanks and bombs carried on the centerline rack could only be released by using the manually operated emergency rack release."
Hi: How did the center bomb rack get the bomb or torpedo clear of the prop? This is a requirement for all propeller driven dive bombers. Note the SBD uses a trapeze mechanism to do that. Otherwise the bomb will hit the propeller. See patents at: http://www.prc68.com/I/Aircraft.shtml#BombPatents
ReplyDeleteA small explosive charge in the bomb rack was used to positively push the store away from the fuselage.
DeleteHi all. Interesting reading. I am building an A1J and wonder if you have any info on the locations for the pylon safety pins? You seldom see images of SPADS armed without these fitted. Thanks in advance, Chris B. UK
ReplyDeleteSpecifically interested if the AD-4NA had a centerline pylon. Did its manufacture precede the AD-4B such that it did not have the pylon or was it a later production such that it would be present?
ReplyDeleteDavid: I'm pretty sure that the AD-4NA did not have the external center pylon but there is a possibility that one was added at some point by a Navy repair and overhaul depot.
ReplyDeleteI am curious if you know that the box is between the landing gear and starboard inboard pylon in this photo (I hope the link works).
ReplyDeletehttps://i.imgur.com/jd2ORvB.jpg
That's a strike camera
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