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Search: Posts Made By: SplineDrive
Showing results 1 to 23 of 23
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Forum: Rotorheads
20th Mar 2024, 02:20
Replies: 100
Views: 7,177
Posted By SplineDrive

On a teeter rotor with no pitch flap coupling and...

On a teeter rotor with no pitch flap coupling and no hub spring rate, the first flap frequency is at 1/rev, i.e resonance with the rotor rpm. A system in this state has a phase lag of 90 degrees....
Forum: Rotorheads
28th Feb 2024, 11:44
Replies: 13
Views: 1,288
Posted By SplineDrive

Notice what's missing? An X-2 configuration....

Notice what's missing? An X-2 configuration. Sikorsky management must realize that after a billion+ dollars invested in a dead end technology, they need to play catch up on winged configurations with...
Forum: Rotorheads
17th Feb 2024, 14:08
Replies: 186
Views: 38,902
Posted By SplineDrive

Personally, FARA was always strangely...

Personally, FARA was always strangely incompatible with FLRAA, particularly the range and thus speed requirement. If one of the goals of FLRAA was giving the Army a credible Pacific combat capability...
Forum: Rotorheads
22nd Dec 2023, 15:18
Replies: 2
Views: 1,314
Posted By SplineDrive

It's the stiff out of plane rotor head that is...

It's the stiff out of plane rotor head that is wholly impractical for a two bladed rotor on a passenger carrying aircraft. While a stiff out of plane rotor can be trimmed with cyclic for various...
Forum: Rotorheads
4th Nov 2023, 13:25
Replies: 186
Views: 38,902
Posted By SplineDrive

I gently disagree... X-2 aircraft do have a...

I gently disagree... X-2 aircraft do have a commercial application, just not the one Sikorsky intended: they will all make good museum pieces.
Forum: Rotorheads
24th Oct 2023, 17:12
Replies: 186
Views: 38,902
Posted By SplineDrive

Several posters here talking about Raider-X...

Several posters here talking about Raider-X having a serious speed advantage over Invictus and Evalu8er mentions closing the gap to a V-280 escort with Raider-X since it will be much faster than the...
Forum: Rotorheads
15th Oct 2023, 14:13
Replies: 186
Views: 38,902
Posted By SplineDrive

Odds on favorite could be program cancellation,...

Odds on favorite could be program cancellation, but let's see what the Army AoA says. Both teams will have their engines very soon and it'll be game on to get in the air. Then we'll see if Raider-X...
Forum: Rotorheads
9th Oct 2023, 11:22
Replies: 186
Views: 38,902
Posted By SplineDrive

Looks like Raider-X is complete enough to put...

Looks like Raider-X is complete enough to put together a sizzle reel for AUSA.
Sikorsky video link
...
Forum: Rotorheads
4th Jun 2023, 15:53
Replies: 40
Views: 5,535
Posted By SplineDrive

I'll bite, but I'll preface this that my opinion...

I'll bite, but I'll preface this that my opinion is counter to the eVTOL industry trend.

Wisk has moved to the increasingly common "lift + tilt cruise" approach for distributed lift. Their front 6...
Forum: Rotorheads
22nd May 2023, 11:57
Replies: 40
Views: 5,535
Posted By SplineDrive

My comment about an X-2 style aircraft losing to...

My comment about an X-2 style aircraft losing to a simple winged helicopter was a reference to the US Army FARA competition where the Sikorsky Raider-X is pitched against the Bell Invictus.

I have...
Forum: Rotorheads
22nd May 2023, 11:40
Replies: 40
Views: 5,535
Posted By SplineDrive

Because people fly aircraft to the point of...

Because people fly aircraft to the point of energy exhaustion and errors/mistakes are made in the energy loading/consumption process. Should we have passenger fixed wing aircraft that can't glide?...
Forum: Rotorheads
21st May 2023, 15:30
Replies: 40
Views: 5,535
Posted By SplineDrive

There's a couple of key differences between...

There's a couple of key differences between lifting an aircraft vertically with "blowing air" and pushing it forward via "blowing air". Lifting an aircraft requires generating enough thrust to...
Forum: Rotorheads
21st May 2023, 15:10
Replies: 40
Views: 5,535
Posted By SplineDrive

X-49 as a research platform has been going on for...

X-49 as a research platform has been going on for a while, but not a ton of public data. The configuration adds a wing (which is key to high speed performance with a flapping rotor) and the ducted...
Forum: Rotorheads
20th May 2023, 19:22
Replies: 40
Views: 5,535
Posted By SplineDrive

eVTOL got "high end money" back when interest...

eVTOL got "high end money" back when interest rates were near zero. A cash crunch is coming soon and most of the players won't survive their cash burn rates as certification is delayed. The FAA cert...
Forum: Rotorheads
20th May 2023, 14:33
Replies: 40
Views: 5,535
Posted By SplineDrive

Aside from the technology involved, which is hard...

Aside from the technology involved, which is hard enough, you're right that the finances required to get a certified product in customer hands and have the stability to support a growing fleet is...
Forum: Rotorheads
19th May 2023, 14:42
Replies: 271
Views: 54,276
Posted By SplineDrive

“Declutching” down to a slow rpm basically...

“Declutching” down to a slow rpm basically eliminates the blade tip noise from the prop which, like a tail rotor, is far worse than the main rotor noise. Being low to the ground, blade tip erosion...
Forum: Rotorheads
26th Apr 2023, 19:06
Replies: 271
Views: 54,276
Posted By SplineDrive

If Sikorsky doesn’t win FARA, X-2 Technology is...

If Sikorsky doesn’t win FARA, X-2 Technology is dead for another few decades until people forget why it died in the first place… again. I don’t see any European group being willing the fund the...
Forum: Rotorheads
23rd Apr 2023, 23:21
Replies: 271
Views: 54,276
Posted By SplineDrive

Boeing's FARA wasn't simple or conventional. It...

Boeing's FARA wasn't simple or conventional. It was a thrust compounded single main rotor helicopter which is more complex than Bell's lift compounded design. Both are simpler than Sikorsky's...
Forum: Rotorheads
14th Apr 2023, 22:17
Replies: 271
Views: 54,276
Posted By SplineDrive

https://www.gao.gov/assets/820/818991.pdf ...

https://www.gao.gov/assets/820/818991.pdf

Here is the full GAO report for public consumption. I know this forum probably wants to read the juicy details of an evaluation between a thrust...
Forum: Rotorheads
6th Apr 2023, 19:33
Replies: 271
Views: 54,276
Posted By SplineDrive

https://www.gao.gov/press-release/gao-statement-pr...

https://www.gao.gov/press-release/gao-statement-protest-sikorsky-aircraft-corporation%2C-b-421359%2C-b-421359.2

Looks like Bell won FLRAA… again.

“In denying the protest, GAO concluded that the...
Forum: Rotorheads
6th Jan 2023, 17:29
Replies: 271
Views: 54,276
Posted By SplineDrive

Yes, Sikorsky flew a modified S-61 called the...

Yes, Sikorsky flew a modified S-61 called the S-61F that could add wings, jet pods, and a rotating tail rotor along with some aerodynamic cleanup. Sort of a precursor to the S-72 RSRA. They called...
Forum: Rotorheads
15th Dec 2022, 22:14
Replies: 271
Views: 54,276
Posted By SplineDrive

What ability to design new helicopters? Boeing...

What ability to design new helicopters? Boeing has bought/merged into every helicopter in their suite of offerings, or licensed the design for them. Even the YUH-61 had an MBB derived rotor system.
Forum: Rotorheads
8th Dec 2022, 19:37
Replies: 271
Views: 54,276
Posted By SplineDrive

The V-22 is an amazing machine, especially...

The V-22 is an amazing machine, especially considering it’s a 1980’s technology aircraft, but it’s unfortunate that it was the first tiltrotor to go into production because in may ways it represents...
Showing results 1 to 23 of 23


 
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