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Sikorsky S-97 Raider Ground Tests Today

IKE

Nerd Whirler
pilot
Who cares if it's a "helicopter" or not" Do you want a capability or rotors?
That was just a jab. 100% agree with capability >> nomenclature.

I'm wondering where you get the comparison of which type of design is more "robust."
Conversion is what makes tiltrotors more than just a helicopter or a turboprop, but if it breaks (I guess this never happens?), you either can't land in VTOL place or you can't fly very fast. If the pusher prop breaks on a coax, you can still do all the things a helicopter does, just not with those extra 50 kt at the top end. I meant it from an equipment failure perspective, not combat

You're presenting false dichotomy. A tiltrotor is more maneuverable than almost any helicopter. AOB, pitch up/down, G's, linear acceleration, etc are far greater than almost any helo, including a coax.
I'm not talking about maneuvering limits, but things like direction changes, altitude changes without flying forward, back of a DDG at night off Western Australia kind of maneuvering.

I'm trying to figure out why people are so stuck on low-speed manueverability.
The S-97 can hold 15°-ish nose-up in a hover. I'd think the Apache & Cobra crowd would be quite interested in that. The pusher prop also has beta, so you can hold high pitch down w/o accelerating (also useful for attack). For us Navy types, the coax is clearly better for vertrep, dipping sonar ops (not just the hovering, but the repositioning), etc.
 
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phrogdriver

More humble than you would understand
pilot
Super Moderator
What do you mean by “high gain” maneuvers?

To be fair from an escort perspective, you guys are considerably slower on short final than a Huey. In terms of getting to the deck, dropping ramps, and inserting Marines - I’ve seen Yankees do it considerably faster than any Osprey. That’s a function of cabin design with open doors, less pax, and ability to decelerate without doing the conversion on final. That being said, Huey’s are not doing battalion and company sized inserts. I’ve also noticed a significantly faster acceleration out of an objective area from Ospreys than other rotary winged aircraft, but I’ve also seen a decent amount of wave offs more so than 53s and Yankees in some environments due to that high disk loading.

I would imagine most attack platforms replacing Cobras and Apaches will be some version of a tiltrotor in the future. Mainly for loiter time, payload, speed, range, sensor performance, and the ability for increased vertical and horizontal standoff. I wouldn’t knock a hover hold for weapons employment though, there are certain situations that it is pretty effective. The Karbala situation had as much to do with poor planning as it did tactical employment of the aircraft. There are more details to that better not discussed here. It is nice to have the size and ability to maneuver in terrain and accel/decel rapidly from 0-60 kias in elevated threat environments for obvious reasons. I am not sure current tilt rotor technology can do rapid in and out of HOGE/HIGE transitions during contour and NOE flight. Atleast not with an aircraft the size of an Osprey in the terrain that helicopters like to use to their advantage. Not to say that it won’t in the future either.

You have some good points as far as the Osprey. It is, however, operating at around 50K lbs in combat. An FVL platform is likely half that. I'd also say that being able to maneuver like an airplane with the option of going slower is more survivable than being a helicopter that can occasionally go fast.


That was just a jab. 100% agree with capability >> nomenclature.


Conversion is what makes tiltrotors more than just a helicopter or a turboprop, but if it breaks (I guess this never happens?), you either can't land in VTOL place or you can't fly very fast. If the pusher prop breaks on a coax, you can still do all the things a helicopter does, just not with those extra 50 kt at the top end. I meant it from an equipment failure perspective, not combat


I'm not talking about maneuvering limits, but things like direction changes, altitude changes without flying forward, back of a DDG at night off Western Australia kind of maneuvering.


The S-97 can hold 15°-ish nose-up in a hover. I'd think the Apache & Cobra crowd would be quite interested in that. The pusher prop also has beta, so you can hold high pitch down w/o accelerating (also useful for attack). For us Navy types, the coax is clearly better for vertrep, dipping sonar ops (not just the hovering, but the repositioning), etc.

Being able to accelerate and decelerate and change one's velocity vector quickly is what maneuverability is. Outside the 0-20 knot arena, a tiltrotor is probably going to blow the doors off of any compound design. I'm assuming you meant compound as the distinguishing characteristic and not coax. The pusher prop makes it a compound--coax is just the stacked rotors--I'd definitely put a V-22 or a V-280 against a Helix or Ka-50 if we're debating the merits of coaxial rotorcraft.

The conversion actuators in a V-22 aren't prone to failure, seeing as they are triple-redundant. I wouldn't think the compound would fail either, barring pure material failure. That said, I don't think you'll be continuing on your mission either way. You're talking a high-rpm shaft broken and flailing around inside the tail, at least in the compound case.

Why would you want to be nose up in a hover? Nose down, maybe. I've held 10 up and 10 down in a V-22 at twice the gross weight of an S-97. It's a cool parlor trick but not something to hang an acquisition program on.

I think you're making conclusions based on video and promotional materials of an experimental aircraft with hardly any flight time behind it.

Remember that the S-97 is a scout sized (Cap Set I) aircraft. The Navy needs a Cap Set III aircraft (medium lift). The technology of the S-97 has to be scaled up, and Sikorsky is over a year behind timeline and counting in proving it's even possible.

Also, in terms of remaining relevant, long range and high speed are going to be a greater advantage than being great in a hover. A tiltrotor is always going to have a decisive advantage there. Besides, the compound S-97 hasn't demonstrated anything in a hover that the tiltrotor V-280 hasn't.
 
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Griz882

Frightening children with the Griz-O-Copter!
pilot
Contributor
From the perspective of an infantry LZ, I wonder how much the disc rotor size of the V-280 will come into consideration. Sure, there is plenty of open space in the typical Iraq LZ, but I don’t imagine we are planning all of our future operations in nice, wide open spaces. I can tell you that getting more than a squad down using fast rope is quite time consuming.
 

IKE

Nerd Whirler
pilot
Also, in terms of remaining relevant, long range and high speed are going to be a greater advantage than being great in a hover. A tiltrotor is always going to have a decisive advantage there. Besides, the compound S-97 hasn't demonstrated anything in a hover that the tiltrotor V-280 hasn't.
In your mission set, sure. Again, I need to hover at 70 ft for xx minutes, then reposition xx nmi away and get the transducer back in the water within xx minutes. I also need to land on the back of a CRUDES in heavy seas at night AND fit two birds in the hangar. Also, VERTREP.

Like I said, different mission sets = different capabilities/needs.
 

phrogdriver

More humble than you would understand
pilot
Super Moderator
In your mission set, sure. Again, I need to hover at 70 ft for xx minutes, then reposition xx nmi away and get the transducer back in the water within xx minutes. I also need to land on the back of a CRUDES in heavy seas at night AND fit two birds in the hangar. Also, VERTREP.

Like I said, different mission sets = different capabilities/needs.

Neither of those things would in anyway exclude a CapSet 3-sized tiltrotor design.
 

IKE

Nerd Whirler
pilot
Neither of those things would in anyway exclude a CapSet 3-sized tiltrotor design.
I'm not familiar with the CapSet 3 term. Is that V-22 size or smaller? For reference, CRUDES hangars just barely hold a folded H-60 on each side. DDG-1000 will be even tighter.

Also, are you understanding that the very nature of a titlrotor design and the compromises made on rotor size make it less efficient in a hover than a single-main-rotor or coax helicopter, and Navy missions entail much time in hover/low-speed flight?

Also-also, I've flown the V-22, so I'm well aware of how awesome it is, I just don't think tiltrotors are the answer for Navy missions (except COD).
 
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phrogdriver

More humble than you would understand
pilot
Super Moderator
Capability set 3 is H-60 size. 1 is scout. 5 is heavy lift. A V-22 is a 3+ or a 4.

At least in the publicly released videos, I haven’t seen an X-2 or S-97 do anything particularly exciting from a hover, so I’m wondering why the going in position is that a larger version will have especially amazing low-speed maneuverability. More than a V-22? Probably. But a V-22 is over twice the size.

Is dipping that dynamic an environment? I’d think being able to go to a different site farther, more quickly, and with greater endurance due to being wing borne would be worth something.
 

Jim123

DD-214 in hand and I'm gonna party like it's 1998
pilot
A tilt rotor dipper's prop rotors are going to put more noise into the water than the rotor of a same weight dipping helicopter. The tilt rotor’s advantages like a faster sprint and longer range might or might not be worth the trade off and there is a lot of computerized processing you can do about the extra noise and I’m not going to “nuke out” on the explanation, but more background noise never helps with ASW (not unless you’re the target who is trying to get away). Just one more thing to consider.
 

phrogdriver

More humble than you would understand
pilot
Super Moderator
A tilt rotor dipper's prop rotors are going to put more noise into the water than the rotor of a same weight dipping helicopter. The tilt rotor’s advantages like a faster sprint and longer range might or might not be worth the trade off and there is a lot of computerized processing you can do about the extra noise and I’m not going to “nuke out” on the explanation, but more background noise never helps with ASW (not unless you’re the target who is trying to get away). Just one more thing to consider.

I'll confess I didn't know that the aircraft's own noise was a big issue when dipping. Are you talking the actual noise of the engine and rotors going from the air into the water, or do you mean because of the downwash hitting the water? That'd be the primary difference between the V-22 and a helicopter of similar weight, I'd think. Nothing that large is exactly whisper quiet while hovering.

In normal helicopter noise situations, the biggest noise producer on a normal helicopter is usually the tail rotor, and the V-22 doesn't have that (not to say it's not loud). However, it's a higher frequency noise, so probably wouldn't propagate through the water as much. It does propagate through the air better than engine or rotor noise, though, which is why Hawaii tour operators almost all use fenestron tail helos due to strict noise controls.

I guess what I'm asking is whether this is actually something that's been looked into as far as ASW, or are you making an educated guess to some degree or another?
 

IKE

Nerd Whirler
pilot
For dipping, it's the efficiency, not the maneuverability that concerns me. Where I want hover maneuverability is over the back of the boat and during vertrep. I don't want any of that one rotor IGE, one rotor OGE stuff that was a hurdle to the V-22 landing on LHDs back in its DT days.

To keep it at the AW class level, while getting from a ship to an ASW datum quickly matters, 280 vs. 250 knots top speed doesn't matter as much as repositioning between dips, which happens on the order of minutes (in an H-60 at about 120 KIAS). Obviously, either solution will outclass the H-60 chasing a datum, but any datum provided by the SWOs is probably garbage anyway. And, like I said, hover efficiency matters, since idk, 50% or more of an ASW sortie might be spent in a HOGE.

Own helo noise matters both for counterdetection and sensor performance, but is usually only a concern for the first item. I don't know what happens to low vs. high frequencies when they refract at the air-water interface, but in general the propagation difference between low and high frequencies in the water is overblown (for tactical ASW units). The difference between 10 Hz and 10 kHz is < 2 dB prop loss over 5 nmi.
 

phrogdriver

More humble than you would understand
pilot
Super Moderator
There no problem with one rotor in HOGE and one out, at least not anymore.

Then there’s the fact that I saw a V-280 flying over I-20 in Arlington today, and the SB-1 only exists in someone’s imagination. 3ED519E2-0799-43EC-BFB5-DDA968F7FCA2.jpeg
 

Jim123

DD-214 in hand and I'm gonna party like it's 1998
pilot
I guess what I'm asking is whether this is actually something that's been looked into as far as ASW, or are you making an educated guess to some degree or another?
Ike answered it better than I could.

I wasn't making an educated guess so much as asking an educated question.
 
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