Saturday, December 6, 2025

Lockheed T-33 Tip Tank

 12 December 2025: Slightly different overall dimensions have been reported based on measuring tanks or ones on display aircraft, lengths of 182", 182.5", and 186" and diameters (constant section) of 25.5", 25.78" and 25.783", which sounds like a conversion from a metric measurement. The 182.5" is reportedly also taken from a stations diagram, which is close to a gold standards; the 25.5" is based on a careful measurement of the circumference of a tank as 80" (a second tank measured slightly less), which calculates to a diameter of 25.465" using pi to five places. I would note, particularly with respect to the somewhat snarky insistence on 25.783", that any of those diameter measurements will suffice since the difference is minuscule at model scales.

Someone asked for the dimensions of the Fletcher tip tank carried by the T-33 (and occasionally seen on the F-84 Thunderjet), so down another rabbit hole I went. Thanks to Jerry Wells, who measured and photographed the example at the National Naval Aviation Museum in Pensacola, this is the result:

One feature is a removable two-piece fairing that covers up the cavity where the tank is attached to the wing tip:

 
 
Ricardo Reis Photo

 Jerry Wells Photo

 
 Jerry Wells Photo

The trailing edge of the fin at the aft end of the tank is angled slightly forward and the tank is mounted with it parallel to the ground, not with dihedral like the wing.

 
 
Jerry Wells Photo

 Note the little access door on the inside of the aft end of the left tank only for storage of safety pins, etc.

 
 
Jerry Wells Photo

 

Monday, November 10, 2025

Boeing B-52 Stratofortress Wing Dihedral

 

 

And now for something completely different but it's a rabbit hole I've explored fairly thoroughly so I thought I'd share. Thanks to Ron VanDerwarker, Rob de Bie, and Haydn Hughes for information.

The B-52 is rightly famous for the bending of its high-aspect-ratio wing in flight as well as on the ground, the amount varying considerably with aerodynamic and fuel loads.

  

Note that the airplane is restricted in g loading to lower numbers operationally but during initial development it was taken to at least 3.5 gs.

Some believe based on three-view drawings and pictures of the airplane on the ground that the B-52 wing has anhedral (wing angled down, also known as cathedral) rather than dihedral (wing angled up).

However, the appearance of anhedral when on the ground is deceptive, a combination of a swept wing viewed at an angle of incidence from the front (also see https://tailspintopics.blogspot.com/2014/03/anhedraldihedral-and-wing-sweep.html) exacerbated by the significant droop of the B-52's wing when fully fueled and stationary.  

This B-52D three-view drawing appears to be both Boeing-generated and accurate, although the top view has slightly greater wing span than the front view, not unusual and resulting from differential sizing of the views.
 
Based on this drawing, I’ve verified that the wing has dihedral:


The blue line is the wing's angle of incidence (6°) relative to the fuselage; the red line is along the wing leading edge. The difference between the two indicates dihedral (I don’t know what definition was used for measuring it, but it was possibly the trailing edge).
 
This Boeing illustration also depicts the dihedral present at the wing root with the scan distortion corrected with red lines:
 
Note that the clearance depicted on the Boeing three-view under the engine pods, external tank, and wing tip is dependent on fuel load in the wing and tip tank.
I’m pretty sure that “jigged" means that the three-view drawing does not show wing droop, i.e. the wing is drawn with a dihedral of 2.5°, which is possibly the case when the wing and tip tank are empty of fuel.
 
With no fuel in the wing or the tip tank, the auxiliary landing gear out on the wing tip would be well off the ground with no wing droop.

 
When generating lift, of course, the wing bent upward along its span.
 
For modelers building a B-52, there are two ways of incorporating wing bending if desired: 1) bending the wing and 2) modifying the angle of the attachment of the wing to the fuselage. The latter is incorrect and doesn't accurately represent the bending of the wing itself along its span but is an easier way of positioning the wing tip correctly with respect to the ground for a given fuel load. Nevertheless, Haydn Hughes did the former successfully: "Back in 2002 I made a couple of saw cuts in each wing of slightly different widths and inserted strips of plastic card until I got what I thought was a reasonable 'bend' in the wing. This did mean I had to replace the vortex generators though!"
 
My guess is that it would be more accurate to make the saw cuts perpendicular to the leading edge.
 
Another suggestion for bending the wing is to assemble the wing halves and then make razor cuts in the lower wing (probably best perpendicular to the leading edge and including a bit of the leading and trailing edge of the upper wing) and then gluing the gaps closed. Note that the wing outboard of the external tank will have very little if any droop. 

Monday, March 31, 2025

Ginter Books

 

 Steve Ginter no longer has his own website but he is still creating and publishing books. You can contact him directly for availability and pricing (nfbooks@sbcglobal.net ) or look for them here: https://daviddoylebooks.com/search?q=Ginter