Torque Tube Research Articles

Practical problems in calibration of torque tubes

Static calibration of torque tubes transmitting 30 MW at 6,000 rpm was required to an accuracy of 0.1%. The technique used is described and the various sources of error are analysed and discussed.

Practical superconducting generators

A superconducting synchronous generator consists of superconducting field winding, nonmagnetic multi-tubular rotor and airgap armature winding. The superconducting generator has the benefits of 1/2-2/3 weight reduction and 0.5-0.8% efficiency improvement compared with the conventional generator, and the economic crossover between them appears to be 0.5-1.5 GVA.The problems discussed are (1) property, cooling and support of superconducting field winding, (2) thermal contraction of cryogenic torque tube, (3) tubular damper configuration, (4) seal of helium transfer coupling, (5) transposition, cooling and support of airgap armature winding, (6) vibration of the rotor.

Longitudinal shear strength of Douglas-fir

Weibull's theory of brittle fracture is applied to the determination of strength of Douglas-fir wood in longitudinal shear. Ultimate stresses, at a given survival probability, are derived for beams under different loading conditions. The theory allows an explanation for the difference in shear strength between beams and the standard American Society for Testing Materials shear block, as well as for the dependence of shear strength upon beam size. The theory is verified by comparing theoretical predictions and test results on Griplam nailed connections loaded parallel to the grain and shear tests on torque tubes. Very good agreement is shown. Finally, allowable shear stresses for beams under different loading conditions are derived.

Impact tests of a graphite-epoxy helicopter tail rotor blade

Full-scale whirl impact tests simulating tree strikes and low-velocity wrench drop tests have been conducted on a full-scale graphite/glass-epoxy 11 ft dia. two-bladed tail rotor. Damage following whirl impact of 1 2 in and 1 in dia. hard maple wood dowels and a 1 1 4 in dia. maple tree branch was limited to the trip cap and tip balance weight retention bolts and was not sufficient to cause a mission abort. Low-velocity impact tests were performed by dropping a 1·6 lb wrench and a 1·9 lb steel projectile from a height of 12 ft on to various areas of the blade. The construction of the blade, which completely encases the graphite-epoxy spar with a glass-epoxy torque tube and aerodynamic shell, proved to be relatively invulnerable to this type of hazard.

Material selection for the torque tubes of large superconducting rotating machinery

This report identifies properties to be considered when selecting materials used in construction of torque tubes for rotating superconducting field windings in electrical machinery. The main design requirements are stated and the groups of material properties that influence directly the mechanical and thermal performance of a torque tube are derived. Most desirable is a low thermal conductivity to modulus of elasticity ratio which governs the refrigeration expenses and the tube wall aspect ratio (thickness/length). Numerical examples point out that fibre-reinforced plastics are potential candidates for use in torque tubes.

Month in the Patent Office

In an aircraft, specifically a guided missile wherein the missile shell 10 carries a stub wing 16 to which is hinged a folding wing 11 which folds about a fore‐and‐aft axis 12 on the wing lower surface and a control surface 13 is hinged to the wing part 11 about a transverse axis 14 displaced vertically from axis 12, control means for surface 13 comprises a two‐part control torque tube 15A, 15B, part 15B being mounted in bearings 17 in part 11 and fast with surface 13. The connexion between the parts of the torque tube comprises a slotted member 23 fast with part 15A and a tongue member 20 of L‐shape fast with part 15B, and of such proportions that, as shown by chain dotted lines, the two parts remain in operative engagement when the wing part 11 folds downwardly about axis 12. The wing‐folding and surface‐adjusting mechanisms are inter‐connected to ensure that the slotted member 23 is correctly oriented before wing folding commences.