Bell/Boeing V-22 Osprey

[Warbird Keith]

DUSTY22

[Scott Youmans]

Post Hop

[bilwor]

Bell/Boeing MV-22B Osprey 168012 YX-11 VMM-166 Sea Elk   WTI 1-13 MCAS Yuma

[Brian Lockett]

Bell-Boeing MV-22B Osprey BuNo 167909 modex 07 of VMM-162 Golden Eagles at MCAS Yuma on October 23, 2012..

[Jay Beckman]

Caught "'between-ing" at Thunder Over Utah

[Jeff D. Welker]

^^^^ If this doesn't win the "Steady-Eddie" slow shutter speed panning award, I'm not sure what/who would. Great image Jay!

[Jay Beckman]

Thanks Jeff

[Scott Youmans]

Yes indeed.  What was that? Something like 1/30 sec?  Very nice.

[Jay Beckman]

Indeed it was at 1/30

[Scott Youmans]

I'd better play the lottery this week.  In truth I figured out once what shutter speed is required to get a full disk with an Osprey.  As I recall it turns out to be 1/15 sec for the rotor to turn 120 degrees.

[Jay Beckman]

I'm not sure that even 1/15 would ensure full disc.  Those rotors are sooo big.

I've tried Sky Crane at 1/10 and that wasn't slow enough for a five-blade rotor head.

1/8 down to 1/4 is probably a safer bet.

[Dave S.]

The only reference to rotor speed that my friend Google and I could locate was for 332 rpm in forward flight (found in some NASA study).  To get 120 degrees at 332 rpm, Scott had it right - 1/15 of second.  This seems to jive with Jay's photo taken at 1/30; which gave about 60 degrees of rotation (or about 1/2 of what was needed for a full disc).  So, to double the rotation on a three bladed prop/rotor (60 -> 120), just double the time the shutter was open and that results in Scott's 1/15 shutter speed.

So Wow to Jay for holdin' her steady at 1/30!  Can we 'double' down on that and see who can get a steady shot at 1/15?

The next question, is rotor/prop speed relatively constant for the V-22, or does it vary depending upon flight regime/condition?

[BillOz]

Usually Turboshafts run at a fairly constant rpm throughout the flight regime, but this one may be a little different between vertical and horizontal ops.  Probably not much difference though, if any.

Info I found indicates a prop tip speed of 662 ft/s., which works out to 331 rpm, so that matches with the info you found Dave.

So a shutter speed of 1/15 should give just a little more overlap than a full disc.

[Joe Copalman]

It's been a while, and I wasn't taking notes, but I recall the V-22 ferry pilot we met at Willie telling Jack and I that rpm was constant and that power/speed were controlled through nacelle angle and blade pitch. 

[Scott Youmans]

That sounds correct. Fairly typical for gas turbines.