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Forum: Rotorheads

11th Sep 2017, 19:02

Replies: 85

Sikorsky + Boeing pitch ‘X-2’-based design for US Army JMR TD effort

Views: 35,850

Posted By SansAnhedral

Defiant?s delay due to blade manufacturing...

Defiant?s delay due to blade manufacturing challenges (http://www.defensenews.com/digital-show-dailies/dsei/2017/09/11/defiants-delay-due-to-blade-manufacturing-challenges/)

Well, clearly they...

Forum: Rotorheads

20th Aug 2014, 12:44

Replies: 85

Sikorsky + Boeing pitch ‘X-2’-based design for US Army JMR TD effort

Views: 35,850

Posted By SansAnhedral

The X-49 fell well short of its speed goals, and...

The X-49 fell well short of its speed goals, and the tech was not chosen to be pursued in JMR mainly due to those concerns.

Forum: Rotorheads

18th Aug 2014, 13:20

Replies: 85

Sikorsky + Boeing pitch ‘X-2’-based design for US Army JMR TD effort

Views: 35,850

Posted By SansAnhedral

Rigid rotor tip path plane divergence at larger...

Rigid rotor tip path plane divergence at larger rotor diameters.

The rotor scales essentially infinitely aerodynamically on paper. Building sufficiently light and rigid blades is the issue.

You...

Forum: Rotorheads

1st Jul 2014, 14:42

Replies: 85

Sikorsky + Boeing pitch ‘X-2’-based design for US Army JMR TD effort

Views: 35,850

Posted By SansAnhedral

The rotor center of rotation is at a higher...

The rotor center of rotation is at a higher waterline, but the disc declination puts them at interference. In the -47 the rotors intermesh at any Nr > 0 where CF stiffening and flapping/coning is in...

Forum: Rotorheads

26th Jun 2014, 14:49

Replies: 85

Sikorsky + Boeing pitch ‘X-2’-based design for US Army JMR TD effort

Views: 35,850

Posted By SansAnhedral

Well this certainly is interesting Boeing...

Well this certainly is interesting

Boeing proposes high-speed Apache, heavier Chinook - 6/26/2014 - Flight Global...

Forum: Rotorheads

23rd Jun 2014, 14:44

Replies: 85

Sikorsky + Boeing pitch ‘X-2’-based design for US Army JMR TD effort

Views: 35,850

Posted By SansAnhedral

That is a bit of a stretch. Concept development...

That is a bit of a stretch. Concept development is one thing, but expertise in helicopter design does translate especially well to the world of tiltrotors, especially in the arena of rotor dynamics. ...

Forum: Rotorheads

20th Jun 2014, 13:51

Replies: 85

Sikorsky + Boeing pitch ‘X-2’-based design for US Army JMR TD effort

Views: 35,850

Posted By SansAnhedral

That would be prudent, provided they understand...

That would be prudent, provided they understand the idea of diminishing returns and non-linear relationships.

2 data points does not make a curve.

Forum: Rotorheads

19th Jun 2014, 13:50

Replies: 85

Sikorsky + Boeing pitch ‘X-2’-based design for US Army JMR TD effort

Views: 35,850

Posted By SansAnhedral

Sikorsky will do their best to use the S97 as a...

Sikorsky will do their best to use the S97 as a flying billboard for the FVL X2 based technology, despite the fact that scaling issues are unavoidable, and I maintain that the demonstration of yet...

Forum: Rotorheads

21st Oct 2013, 19:38

Replies: 85

Sikorsky + Boeing pitch ‘X-2’-based design for US Army JMR TD effort

Views: 35,850

Posted By SansAnhedral

Perhaps Gene Roddenberry's estate made out well ...

Perhaps Gene Roddenberry's estate made out well

http://images2.wikia.nocookie.net/__cb20090215194746/memoryalpha/en/images/f/f9/USS_Defiant,_NCC-1764.jpg
...

Forum: Rotorheads

21st Oct 2013, 19:05

Replies: 85

Sikorsky + Boeing pitch ‘X-2’-based design for US Army JMR TD effort

Views: 35,850

Posted By SansAnhedral

SB>1? Assuming SB is Sikorsky-Boeing ...

SB>1?

Assuming SB is Sikorsky-Boeing

What is with the ">" ???

Forum: Rotorheads

11th Oct 2013, 14:38

Replies: 85

Sikorsky + Boeing pitch ‘X-2’-based design for US Army JMR TD effort

Views: 35,850

Posted By SansAnhedral

Ah good catch, my initial recollection was that...

Ah good catch, my initial recollection was that he was from Mil, but for some reason I thought Kamov due to their historical experience with coax.

Forum: Rotorheads

11th Oct 2013, 13:09

Replies: 85

Sikorsky + Boeing pitch ‘X-2’-based design for US Army JMR TD effort

Views: 35,850

Posted By SansAnhedral

The JMR TD paper proposal did not cost $100M....

The JMR TD paper proposal did not cost $100M. Sikorsky basically confirmed they were going to fly the essentially-existing S-97 as the demonstrator, despite it clearly being far undersized for FVL-M....

Forum: Rotorheads

10th Oct 2013, 18:25

Replies: 85

Sikorsky + Boeing pitch ‘X-2’-based design for US Army JMR TD effort

Views: 35,850

Posted By SansAnhedral

Still have yet to hear an explanation as to why...

Still have yet to hear an explanation as to why the fairings never made it on the aircraft from the onset.

1G was a swag number, I was attempting to illustrate any given substantial maneuver on a...

Forum: Rotorheads

10th Oct 2013, 15:16

Replies: 85

Sikorsky + Boeing pitch ‘X-2’-based design for US Army JMR TD effort

Views: 35,850

Posted By SansAnhedral

I should qualify that thick roots are not...

I should qualify that thick roots are not necessarily penalizing due to reverse flow, but with a typical helicopter the thick root would likely see closer to zero flow on the retreating side (and...

Forum: Rotorheads

9th Oct 2013, 11:45

Replies: 85

Sikorsky + Boeing pitch ‘X-2’-based design for US Army JMR TD effort

Views: 35,850

Posted By SansAnhedral

Thats debatable, in airplane mode on a tiltrotor,...

Thats debatable, in airplane mode on a tiltrotor, a high t/c ratio becomes more frontal area profile drag and essentially equivalent to a much larger spinner....all of which put a cap on Vmax. It...

Forum: Rotorheads

8th Oct 2013, 13:07

Replies: 85

Sikorsky + Boeing pitch ‘X-2’-based design for US Army JMR TD effort

Views: 35,850

Posted By SansAnhedral

Actually, thats part of the entire equation....

Actually, thats part of the entire equation. Structurally, blade "thickness" is a result of stiffness targets and material capabilities.

Generally low speed helicopters live with blades designed...

Forum: Rotorheads

7th Oct 2013, 17:21

Replies: 85

Sikorsky + Boeing pitch ‘X-2’-based design for US Army JMR TD effort

Views: 35,850

Posted By SansAnhedral

An over-simplified explanation (hinted in post #4...

An over-simplified explanation (hinted in post #4 above):

Cruise speed is driven primarily by profile drag at these velocities

~40% of rotorcraft drag is driven by hub area

Hub area is...

Forum: Rotorheads

7th Oct 2013, 12:21

Replies: 85

Sikorsky + Boeing pitch ‘X-2’-based design for US Army JMR TD effort

Views: 35,850

Posted By SansAnhedral

The mere idea that an S-97 is an appropriate...

The mere idea that an S-97 is an appropriate demonstrator for an FVL contract is flat out preposterous. The ABC coaxial design simply does not scale up to the size mandated by FVL-medium and above...

Forum: Rotorheads

1st Mar 2013, 15:13

Replies: 85

Sikorsky + Boeing pitch ‘X-2’-based design for US Army JMR TD effort

Views: 35,850

Posted By SansAnhedral

In other news, supplies of unobtanium will be...

In other news, supplies of unobtanium will be running short as Sikorsky will be buying the remaining quantities to construct high-hinge offset infinitely rigid closely-spaced blades at large spans...

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