Is it true that the Vultee A-31 Vengeance was the only true divebomber in that when attacking, the pilot put the plane into a vertical dive rather than at an angle. I should imagine it made attacks more accurate?
There was no angle, we are talking straight down. Of course it was all down to the skill of the pilots.
I don't think the vertical dive made it any better. The Ju-87 and the Dauntless were good dive bombers. As you stated, depends on the skill of the pilot. What makes a dive bomber is the ability for the plane to put the bomb in the trajectory (in a dive) towards it target increasing accuracy compared to level bombing. The vertical dive would be more accurate on stationary objects (bunkers, buildings) but when attacking moving objects (ships, trains) the plane would have to adjust thus forcing it into an angle.
A vertical dive is going to require a higher release point in order to effect a successful pullout than a 70° dive that was standard with the Dauntless. Any small gain in accuracy of the bomb trajectory is likely to be negated by the higher release point.
Maybe they could, but I’m not sure why you would want to. A 90° dive is one of those things that seem like a good idea in theory, but turn out to be not so much in the real world. The advantage of a 90° dive is that the trail angle of the bomb caused by gravity becomes zero. Compensating for trail angle is relatively easy with even a fairly rudimentary bombsight, and thus any advantage is mostly eliminated. The disadvantages of the 90° drive are several. First, bomb/airframe separation at release becomes problematic. The SBD was fitted with a bomb displacement cradle to get the bomb away from the airframe prior to release. This was based on early dive bombing experience where there were instances of damage to the landing gear or propeller at bomb release. In a slightly angled dive, the bomb will fall away from the aircraft, in a vertical dive it will fall with the aircraft. Second, achieving a true vertical dive causes some problems of its own. Wings want to make lift unless they are put into a zero lift attitude. A fully symmetrical airfoil mounted at zero degrees to the aircraft thrust line will make zero lift at a zero angle of attack. Think modern high performance aerobat. They can achieve a 90° flight path with the nose basically pointed straight down. Your average WWII dive bomber with a semi-symmetrical airfoil mounted a few degrees positive to the thrust line for good cruise performance, is going to have the nose tucked beyond vertical to achieve a truly vertical flight path. What does that do to the bomb/airframe separation issue? Next is the issue of wind. The aircraft is diving through a moving airmass, as it would be extremely rare for there to be absolutely no wind throughout its dive. The preferred technique was to dive down wind, putting the sight short of the target as the aircraft moved toward it with the wind, hopefully arriving at release altitude with the sight on the target. Otherwise, the aircraft would actually fly a curved flight path if the pilot attempted to keep the sight on target throughout the dive. Of course this required minor corrections (and experience) during the dive as the wind is rarely constant at all altitudes. In a 90° dive, if the aircraft has overshot, it would require tucking the nose beyond vertical to get back to the target. See above. Release altitude was mentioned previously. Pretty much everything in aviation is a compromise. The 70° dive angle was found by experience to be a pretty good compromise.
MCoffee, Damn dude, those were some very informative posts. I learned a lot. Thank you and here's a salute!
I would think that 90 degree drop would be even more problematic than mcoffee stated, in that the bomb being more streamlined than the plane and less air resistance would accelerate into the prop arc very quickly. You would have to eject it with sufficient force to clear the arc, and moving 1 or 2000 lbs of bomb several feet is going to require a lot of force applied very quickly. I think the SBD used a swinging cradle affair that at the lesser angles gravity would aid in swinging the bomb out away from the plane. I believe that some planes in vertical dives were prone to trying to tuck the nose past the vertical, but that may have been just the higher speed fighters. Follow up Based on the Watanabe detailed line drawings in my book, it appears that the bomb release trapeze on the JU 87D-1 would not have functioned properly in a purely vertical dive as it was designed to hold onto the tapered fins of the type of bomb illustrated (SC1000). The bomb holding points are slotted and would have required the bomb be at an angle less than vertical to be released.
