Like many architects I am fascinated by aeroplane construction. The B29 is particularly interesting due to its circumstances. It was designed and developed to be built with less skilled labour than had been the case with earlier designs and was made with as simple shapes as possible. The B17 is a flow of compound curves but most of the B29 is a cylinder and a cone. The junction of the wings are not blended as in the B 17, but have small fillets. The performance is realised through detail rather than idealised form. A lot of attention is lavished on the front wheel hatch. On the outside (above) the double curvature surface is inherently strong and is kept smooth for the wind with flush rivets. When the ‘plane is landed there is a large space within the hatch where the wheel used to be stowed. In an elegant innovation this space is used as an entry hatch for the crew to enter the ‘plane, so that openings that weaken the airframe are kept to a minimum (below).
The wheel hatch doors have pressed inner skins that have a depth to provide strength. As they are mostly out of the wind (except for take off and landing) they are fixed with domed rivet heads. The inner skins are connected to the outer surface at the perimeter and some dished sections to make connections across the centre of the hatch doors (see below).
The structural depth of these two skins protrudes into the space occupied by the landing gear when the wheels are stowed during flight. To overcome this packaging problem there are dimples pressed into the inner skin to accept the front
wheel (see below).
In quite a simple door there are therefore a number of elegant negotiations to get all the parts to work together.
This example is from Duxford but there is another one on display at PIMA in Tucson.
There is a film on youtube about the making of the B 29 that you might enjoy – find it here
If only I could find someone who went around poring over small details of aircraft design as a full time thing! Alas, to many of them just repeat the same big picture rehash of wikipedia, with a shot of the crew positions if you re lucky and some exterior shots. It’s amazingly hard to find out simple things like “how do the crew access the aircraft”, for example. No one seems to think it’s worth showing the 1,000 small details, but thats exactly what I am interested in. Thanks for this.