old airplanes - what is this thing for?

The thing at the top of this airplane Looks like a bomb but on the wrong side.

Fuel tank?

Could it be a fuel tank? There’s one underneath as well, both are on the line of the centre of gravity, and it’s a civvie plane.

The plane looks (mostly) like a Blériot XI.

In these two photos of a Blériot XI, photo 1 and photo 2 there is some sort of stabilizer mounted above the pilot with a pair of supports connected by a wire above the pilot. The stabilizer (or whatever it is) is not normally associated with that plane, as seen in this photo.

My guess would be that an artist, unfamiliar with the newfangled aircraft, saw a picture of the version mounting the extra stabilizer and interpreted it as a fuel tank in an imaginative drawing. The lower tank probably has the same provenance: artistic license inspired by a lack of genuine information.

(My guess is that no plane of that time, with their 25 - 50 h.p. engines, could have lifted a fuel tank that large off the ground when further encumbered by a pilot. A 30 gallon tank would have added 240 lbs. to the aircraft, and placing it above the pilot would have made the whole thing rather unstable.)

Not only that, but a fuel tank above the center of mass of the airplane like that would be destabilizing. Slung under the airplane it would be stabilizing. Also, if there was a fuel leak, it would leak all over the structure and pilot. I can’t imagine anyone designing a fuel tank like that.

Actually, now that I think about it I can come up with a couple of reasons - one would be to use gravity feed to fuel the engine. Another would be to compensate for the added extra roll stability created by having an equivalent tank slung underneath. If the airplane didn’t have enough roll authority to be manoevable with a low-slung external tank, you could put one equidistant from the center of mass on top and bottom and they would cancel each other out.

While we’re at it, what are those things on the trailing edge of this 727’s wings?

727 Pic

I asked the captain of a flight once but I forget what he said. Obviously they serve
some sort of aerodynamic function, but what exactly?

Did you see the recent issue of AOPA Pilot? The plane on the cover (incidentally, flying over Whatcom County :slight_smile: ) has a high-mounted engine with the fuel and oil tanks behind it in a pod.

Sorry. It’s on the Contents page. Just pulled out the magazine, and the article starts on page 74. The aircraft is a Curtis-Wright CW-1 Junior. The magazine aircraft has been modified with a 9-cylinder Salmson AD-9 radial engine.

Fuel tank. Most of the airplane looks like a Bleriot, but that doesn’t mean anything. The artist might have simply remembered the Bleriot style the best, and added the fuel tank as artistic license based on some other design he’d seen. I would not be surprised to see a fuel tank there, since it facilitates gravity feed.

Note that the caption seems to be German, not French.

They are fairings that streamline the flap support and extension mechanisms.

I’ve seen a few seaplanes with that configuration. If the engine is up high, it makes sense to put the tank up high with it, so you don’t have to pump fuel up into the pod. The only purpose for the high mounted engine is to keep the prop out of the water spray from the fuselage. Pod-mounted engines have all kinds of problems. They decrease stability, and they have a bad inverse-pitch problem - because the thrustline is so high, they tend to push the nose down when you add power, and therefore when you’re trimmed out, the nose comes up when you pull the power back. That’s not a good thing - it’s dynamically unstable. So the airplane has to be designed to maintain positive pitch stability in other ways.

Yeah, those are fairings for the flap and aileron mechanisms. If you look at the leading edge, you can also see fences on the wing. These are to help prevent spanwise flow of air from the root out towards the tips, which can cause havoc when an airplane stalls.

Some large jets are just choc-a-bloc with all kinds of devices and gizmos on the wing to help the airplane fly better.

This article explains what they are and why they are that particular shape/size as well.