McDonnell F3H Demon Nose Landing Gear

Most landing gears consist of an oleo or cylinder mounted to aircraft structure and a piston on which the wheel is mounted. The piston functions as a shock absorber. The two are connected with a mechanism that does not allow the piston to twist within the oleo. Often that is a torque link or scissors.

The scissors on the F3H nose landing gear is more complicated than usual because it also provides the means to shrink the unit to fit in a shorter wheel well. Instead of two links, there are three. Two shrink struts, one on each side of the scissors, pull the piston up as the nose landing gear is retracted. Note that the right-hand shrink strut, but not the left-hand,  has a bend in it to provide clearance with the landing gear strut and the lower end of the middle link extends beyond its connection to the lower link.

The shrink link is angled slightly downward and does not move as the piston absorbs the shock of landing. The middle and lower links keep the oleo and the piston aligned.

However, as the landing gear is retracted, the location of the upper mounting point of the shrink struts ahead of the mounting point of the landing gear strut causes the shrink link to be rotated upward to be parallel to and lie against the oleo. Since the pivot point between the shrink link and the middle link has moved up, the middle link moves up, pulling the lower link and the piston with it, shortening the nose landing gear assembly.

The lower section of the middle link that extends beyond the pivot point either keeps the scissors from over-centering or takes some of the load off the pivot point, possibly both.

Grumman S2F/WF/TF Engine Nacelle Detail

Every once in a while someone asks a simple question about an airplane I happen to know quite a lot about and I don't know the answer. In this case, it was the engine exhaust system on the Grumman S2F/WF/TF (S-2/E-1/C-1). The upper exhausts are obvious (this is a picture of an early S2F-1):

The question basically was, did the exhaust gas from all of the cylinders come out here or were there other exhaust stacks on the nacelle. You'd think the answer would have been included in the S2F monograph that I wrote with Bob Kowalski (see http://tommythomason.com/books/grumman-s2f/). It wasn't.

It turns out that in addition to the two troughs on the top of the nacelle there was a third, virtually identical one located on the bottom of the nacelle:

It ended at the forward edge of the oil cooler door. Note the convex stiffener running longitudinally down the center of the trough. The oil cooler door is open in the following picture:

My guess is that there were also two pipes located here that were the exhaust system for the lower four cylinders of the Wright engine.

This is an illustration of some of the engine nacelle panels:

Item 11 is the panel that includes the lower trough. Item 10 is the oil cooler exit and door. Item 4 is one of the two upper troughs (5 is an insulation blanket).

Interestingly, this trough is represented on the ancient Hasegawa 1/72nd S2F kit, another example of its high level of accuracy particularly compared to the much newer 1/48th kit from a different manufacturer...