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Search: Posts Made By: riff_raff
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Forum: Rotorheads
22nd Aug 2017, 05:06
Replies: 488
Views: 209,724
Posted By riff_raff

Sans- In this video of a tie-down run of...

Sans-

In this video of a tie-down run of the S-97 you can see how the pusher prop drive is de-clutched as the main rotors come up to speed. If my understanding is correct, doesn't the S-97...
Forum: Rotorheads
6th May 2017, 06:00
Replies: 488
Views: 209,724
Posted By riff_raff

I believe one advantage of tilt rotors versus...

I believe one advantage of tilt rotors versus helos is their ability to quickly climb and cruise at altitudes beyond MANPADS. There are many things Bell can do to reduce detection of this tilt rotor....
Forum: Rotorheads
29th Apr 2017, 07:32
Replies: 488
Views: 209,724
Posted By riff_raff

"Bearingless" rotors still have some arrangement...

"Bearingless" rotors still have some arrangement that permits adjustment of the blade pitch. Usually a torsionally flexible attachment structure or a laminated elastomeric bearing. However, they do...
Forum: Rotorheads
23rd Apr 2017, 05:46
Replies: 488
Views: 209,724
Posted By riff_raff

The justification for these flight demonstrators...

The justification for these flight demonstrators was risk reduction and minimizing schedule delays in the production aircraft program. Both Bell and Sikorsky have the financial/manpower/manufacturing...
Forum: Rotorheads
13th Apr 2017, 05:46
Replies: 488
Views: 209,724
Posted By riff_raff

Blade fold systems always seem to add a...

Blade fold systems always seem to add a significant amount of complication. Not easy to do cleanly.
Forum: Rotorheads
11th Mar 2016, 01:30
Replies: 488
Views: 209,724
Posted By riff_raff

CTR- In your post of March 7, you voiced concern...

CTR- In your post of March 7, you voiced concern about "momentary engine failure" when the S-97 would be flying close to ground level. What type of event do you see causing a momentary engine...
Forum: Rotorheads
9th Mar 2016, 00:00
Replies: 488
Views: 209,724
Posted By riff_raff

Lonewolf_50 brings up a good point in post #143...

Lonewolf_50 brings up a good point in post #143 about improved engine reliability. The S-97 currently uses the YT706, but I'm sure Sikorsky intends to use the ITEP engine (GE3000...
Forum: Rotorheads
6th Mar 2016, 22:20
Replies: 488
Views: 209,724
Posted By riff_raff

CTR- I hope you'll pardon the fact that I'm not...

CTR- I hope you'll pardon the fact that I'm not an Army pilot, but here is how Lockheed-Martin-Sikorsky management apparently sees the S-97 being applied to the US Army's future rotorcraft needs.
...
Forum: Rotorheads
5th Mar 2016, 05:54
Replies: 488
Views: 209,724
Posted By riff_raff

CTR- I agree that Bell was smart to place a big...

CTR- I agree that Bell was smart to place a big emphasis on cost reduction with their V-280 design. Things like a non-tilting engine and a straight, single piece wing structure reduce both...
Forum: Rotorheads
2nd Mar 2016, 00:57
Replies: 488
Views: 209,724
Posted By riff_raff

In the past two weeks the Army has issued RFI's...

In the past two weeks the Army has issued RFI's for the FVL small variant (CS1) (https://www.fbo.gov/utils/view?id=a5565b60f76fb235432f6779d0a9c97d) and medium variant (CS3)...
Forum: Rotorheads
29th Feb 2016, 02:33
Replies: 488
Views: 209,724
Posted By riff_raff

Sikorsky is going through a change in ownership,...

Sikorsky is going through a change in ownership, and the S97 project is internally funded. So it would not seem unusual for the project to be idled until the business situation at Sikorsky is all...
Forum: Rotorheads
22nd Oct 2015, 00:09
Replies: 488
Views: 209,724
Posted By riff_raff

What you note about tapered roller bearings is...

What you note about tapered roller bearings is essentially correct. The sliding contact between the inner race shoulder and roller end faces generates quite a bit of heat, especially on high speed...
Forum: Rotorheads
20th Oct 2015, 00:00
Replies: 488
Views: 209,724
Posted By riff_raff

SA- That's actually quite an interesting...

SA- That's actually quite an interesting question.

The answer to your question would depend on the specific configuration of split torque transmission. And since the number of potential split ...
Forum: Rotorheads
17th Oct 2015, 22:40
Replies: 488
Views: 209,724
Posted By riff_raff

Lonewolf_50- here's a later AHS paper on the same...

Lonewolf_50- here's a later AHS paper on the same subject if you want to spend $30.

https://vtol.org/store/product/load-sharing-test-of-the-ch53k-split-torque-main-gearbox-2474.cfm
Forum: Rotorheads
15th Oct 2015, 23:39
Replies: 488
Views: 209,724
Posted By riff_raff

Lonewolf_50- Just a couple final comments...

Lonewolf_50- Just a couple final comments regarding the challenge of designing a split torque gearbox.

First, back in 2003 under the AATD RDS-21 program, Sikorsky demonstrated they could get load...
Forum: Rotorheads
14th Oct 2015, 01:54
Replies: 488
Views: 209,724
Posted By riff_raff

I would not consider the split torque design to...

I would not consider the split torque design to present an "order of magnitude" greater difficulty than that of the CH-53E. However, simply growing the existing CH-53E configuration to accomodate a...
Forum: Rotorheads
9th Oct 2015, 00:18
Replies: 488
Views: 209,724
Posted By riff_raff

The 53K MRGB is also a fairly complicated...

The 53K MRGB is also a fairly complicated design, but in a different way than the S-97 MRGB. The 53K has three engines driving a single main rotor, while the S-97 has a single engine driving two...
Forum: Rotorheads
6th Oct 2015, 23:41
Replies: 488
Views: 209,724
Posted By riff_raff

I recall reading somewhere a comment from...

I recall reading somewhere a comment from Sikorsky saying with the S-97 they wanted to accumulate a certain number of hours of drivetrain bench test for each hour of planned flight test. Seems...
Forum: Rotorheads
3rd Jun 2015, 04:00
Replies: 488
Views: 209,724
Posted By riff_raff

One major difference between the V-22 and V-280...

One major difference between the V-22 and V-280 is that all of the rotor moments/forces in the V-22 had to pass thru the gearbox structure.
Forum: Rotorheads
28th May 2015, 02:22
Replies: 488
Views: 209,724
Posted By riff_raff

I would agree with this point. A torque split...

I would agree with this point. A torque split configuration should help reduce the plan view profile of a (intermediate or final) bull gear stage. One major consideration when sizing a bull gear...
Forum: Rotorheads
4th Oct 2014, 04:51
Replies: 488
Views: 209,724
Posted By riff_raff

The most interesting feature shown in these new...

The most interesting feature shown in these new pictures is the engine cowl. Nice clean installation of the single T706. Hard to tell, but it looks like they route the exhaust aft and disharge it...
Showing results 1 to 21 of 21


 
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