The larger props of the Osprey may have greater efficiency over smaller props. The high wing of the Catalina seems to have enough room for larger props. The original PBY had a range of over 2000 miles and was amphibious. Could this old design find use today with modern technology?

  • $\begingroup$ "The larger props of the Osprey may have greater efficiency over smaller props." why? $\endgroup$ – jwenting Dec 4 '18 at 5:04
  • $\begingroup$ See question regarding power requirement comparison of helicopter vs plane. We established that a higher aspect, slower (airfoil) prop is more efficient. See also wing tip vortex cancelling concept of Vought V-173. This work was stopped with the onset of the jet age, but may find application in the high cost of fuel age. $\endgroup$ – Robert DiGiovanni Dec 4 '18 at 9:19

The engines on a PBY-5A Catalina are spaced only about 15' apart. The V-22 Osprey rotors (propellers) have a diameter of 36.1 feet and are much too large.

The engines would have to be moved more that 36' apart for the 18' blades to clear each other. The “high wing” of the Catalina is only about 10' from the water during water operations, and about 14' from the ground during ground operations, so that presents additional clearance problems.

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To scale, putting V-22 props/engines on a Catalina, would look like this:

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    $\begingroup$ The drawing shows a prop diameter of 12' 1 ". But more importantly, the distance between engines is approximately 15' which is less than the 18' radius of the Osprey prop blades. The props hitting the water would be trivial compared to the damage to the fuselage and the other engine. $\endgroup$ – Gerry Dec 3 '18 at 16:37
  • $\begingroup$ Good point.... I have edited my answer in order to improve it. Thanks. $\endgroup$ – Mike Sowsun Dec 3 '18 at 18:05
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    $\begingroup$ The engines would only need to be 18' and some change apart for the radius of the left prop to miss the right engine nacelle. They could be sync'd to interleave to avoid blade collision as they are on the Chinook (and they're linked on the Osprey itself, so the mechanicals are there). However, all the point for "why this won't work" are quite valid. $\endgroup$ – FreeMan Dec 3 '18 at 18:13
  • $\begingroup$ If the nacelles were mounted on the wings an adequate distance apart the rotors could be tilted to avoid striking the ground or water. The V-22 can not land with rotors pitched down either. Also, smaller rotors may be considered. The Vought V-173 "flying pancake" also bears similarities. $\endgroup$ – Robert DiGiovanni Dec 3 '18 at 23:41
  • $\begingroup$ @qq jkztd ok, please lower the nacelles to wing level and a little farther out to avoid striking the fuse. Also, superimpose 25 foot rotors. Thanks. $\endgroup$ – Robert DiGiovanni Dec 4 '18 at 2:11

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