S97 Raider
If you have ever worked in aircraft development and certification you would know nothing is ever simple, rapid, or “clear cut”. Read and learn, all that post simplistic responses on both sides of this discussion.
https://www.ntsb.gov/_layouts/ntsb.a...06X42741&key=1
However, it does seem to me that the 525 was cruising to certification when this accident happened. The inquiry has resulted in a material certification delay, rather unexpected had the cause been as obviously pilot error as was suggested above,
A shroud is not needed for noise control. They have a clutch. I can tell you the X2 main rotor is orders of magnitude quieter than any single rotor helicopter that I've heard. I don't believe this is due to stiffness, just awesome aerodynamics. Regarding vibration, the X2 vibes were lower than a UH60 when it was cruising at 250 kts. We got it there using conventional balancing methods cleaned up with AVC.
Ultralight gyros? How is that relevant?
Ultralight gyros? How is that relevant?
I’m surprised that IFMU didn’t also suggest that SA might also propose an alternative: a compound version of the RAH-66 Comanche for FARA. Now that might get even my attention!
Adding a shroud is not free. Performance gains from a shroud are sketchy and that is weight where you don't need it.
A compounded RAH-66 would have a wing to help offload the rotor as mu increases... that alone should enable the extra speed for FARA with a usable payload. At 180 knots, it wouldn’t need a pusher. I think Sikorsky’s leadership is pretty clear they want an X-2 in the FARA role, regardless if the complexity makes sense for the requirements or not.
Sorry, wasn’t thinking about a wing, only a pusher. Just dreaming, I think. We did wing on/off maneuverability comparison with the S-67 as a NASA or Army contract ( do not recall the sponsor ).
I’ve got those reports on the S-67 somewhere, I recall they’re for the Army. They’re on one of the .mil data servers.
The point was, we achieved some additional Nz capability with the wing, but less than some of us were expecting My point re the pusher was based on guessing that the FARA requirement might include a fairly respectable maneuver envelope at the 180 kt point, and having a pusher would provide for a lower rotor Ct/sigma at 180, allowing that maneuverability. I should add that I haven't a clue as to the FARA maneuverability requirements.
Last edited by JohnDixson; 4th Aug 2019 at 15:46. Reason: add'l statement.
New pictures of the latest mods on S-97. Interesting comment 'way down inside the article' and they made mention of how much 'pointier' the nose is on this prototype.
If you look at the Army's decision to drop the OH-58D and go with "attack helicopters (AH-64) + drones" as their concept for armed reconnaissance, this is an interesting way to achieve that. You could also just load a few hellfires or other Air to Ground munitions based on the mission. The 3 barrel 20mm is hopefully common to this and the Marine AH-1Z (Viper). Joint logistics and all that ... and note that they got rid of that "tail wheel in the tail" in favor of a more conventional tricycle landing gear configuration.
Its modular effects launchers are extended but can be folded into the fuselage to reduce drag during flight. Those pods can also be loaded with other munitions, including air-launched drones. They also can be removed to clear space for assault troops or casualty evacuation.
Lone,
Holy S! This is the most insane weapons configuration I have ever seen for the following:
1. Flight crew will not be happy with missiles stowed in the cabin and aimed at the back of their heads during missions. Will be a significant distraction. One bullet igniting a motor and game over.
2. In an emergency at low level it will be difficult to jettison the weapons to reduce weight and/or get rid of things that go boom before impacting the ground.
3. Unlike Airwolf this configuration looks impossible to deploy symmetrically or asymmetrically at high speeds due to high drag and having gaping holes in the side of the cabin. Anything loose in the cabin will end up going through the pusher.
4. The pusher is directly aft of the weapons and will be impinged face on by the back blast of the missiles. Good way to get things blown off.
Holy S! This is the most insane weapons configuration I have ever seen for the following:
1. Flight crew will not be happy with missiles stowed in the cabin and aimed at the back of their heads during missions. Will be a significant distraction. One bullet igniting a motor and game over.
2. In an emergency at low level it will be difficult to jettison the weapons to reduce weight and/or get rid of things that go boom before impacting the ground.
3. Unlike Airwolf this configuration looks impossible to deploy symmetrically or asymmetrically at high speeds due to high drag and having gaping holes in the side of the cabin. Anything loose in the cabin will end up going through the pusher.
4. The pusher is directly aft of the weapons and will be impinged face on by the back blast of the missiles. Good way to get things blown off.
Lone,
Holy S! This is the most insane weapons configuration I have ever seen for the following:
1. Flight crew will not be happy with missiles stowed in the cabin and aimed at the back of their heads during missions. Will be a significant distraction. One bullet igniting a motor and game over.
2. In an emergency at low level it will be difficult to jettison the weapons to reduce weight and/or get rid of things that go boom before impacting the ground.
3. Unlike Airwolf this configuration looks impossible to deploy symmetrically or asymmetrically at high speeds due to high drag and having gaping holes in the side of the cabin. Anything loose in the cabin will end up going through the pusher.
4. The pusher is directly aft of the weapons and will be impinged face on by the back blast of the missiles. Good way to get things blown off.
Holy S! This is the most insane weapons configuration I have ever seen for the following:
1. Flight crew will not be happy with missiles stowed in the cabin and aimed at the back of their heads during missions. Will be a significant distraction. One bullet igniting a motor and game over.
2. In an emergency at low level it will be difficult to jettison the weapons to reduce weight and/or get rid of things that go boom before impacting the ground.
3. Unlike Airwolf this configuration looks impossible to deploy symmetrically or asymmetrically at high speeds due to high drag and having gaping holes in the side of the cabin. Anything loose in the cabin will end up going through the pusher.
4. The pusher is directly aft of the weapons and will be impinged face on by the back blast of the missiles. Good way to get things blown off.
It is pretty insane. That said, internal weapons carriage has been around for a while and the number of bullets that have hit Hellfires and not ignited motors or warheads, is significant. The risk is high but the likelihood incredibly low.
On the jettison function, I'm thinking the whole doors might go, rather than an open to jettison munition pods. Just a thought.
On the FOD threat to the pusher, via points 3 and 4, I would think that it is of much less consequence to the pusher than that to a tail rotor. You would only lose speed, rather than a total TR drive/control failure. I know which I would prefer to lose.
All great points you have raised. I just saw the pretty pictures until you raised the questions about certain practicalities. Thank you for making me think.
Photo Op
Sikorsky appears to have learned a lesson from Bell after the Defiant fumbles in regards to sticking to promised schedule, and being more open with the press. From the photos it appears their FARA aircraft has progressed well towards first flight. But on close examination of the mast and the weapons carriage, they are obviously wood or plastic mock-ups of real parts. The nose gear reality also looks questionable.
So while I complement Sikorsky on their apparent change in ability to meet schedule and on being more open to the press, I have to wonder how much of the aircraft was just slapped together for a photo op.
So while I complement Sikorsky on their apparent change in ability to meet schedule and on being more open to the press, I have to wonder how much of the aircraft was just slapped together for a photo op.
Doors
Impact of weapon exhaust on the tail has always been a concern and looked at very closely. That’s why the weapons are placed on all helicopters I know of where the tail rotor is not directly behind it. On the Raider the pusher is very big and face on to the back blast. If damaged the pusher wouldn’t just stop working, but be significantly out of balance. If the unbalance is large enough you loose the whole tail.
As to one of your other points about internal weapons carriage; name one helicopter where the missiles are mounted inside the occupied space? They are normally mounted externally or in dedicated weapon bays. When working around military helicopters I always paid attention to the “Armed” warnings and avoided standing in front of the missiles (even knowing if one launched it didn’t have to hit you to cause serious damage to the body). Won’t be able to do that in the Raider.
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You can see the right side door in this picture. https://www.thedrive.com/uploads/202...to2-scaled.jpg
One other things these two photos confirm: On an X2, all usable internal space has to be forward of the mast, making the vehicle have to be longer than a conventional helo of comparable cabin/bay size.
Lone,
Holy S! This is the most insane weapons configuration I have ever seen for the following:
1. Flight crew will not be happy with missiles stowed in the cabin and aimed at the back of their heads during missions.
2. In an emergency at low level it will be difficult to jettison the weapons to reduce weight and/or get rid of things that go boom before impacting the ground.
3. Unlike Airwolf this configuration looks impossible to deploy symmetrically or asymmetrically at high speeds due to high drag and having gaping holes in the side of the cabin. Anything loose in the cabin will end up going through the pusher.
4. The pusher is directly aft of the weapons and will be impinged face on by the back blast of the missiles. Good way to get things blown off.
Holy S! This is the most insane weapons configuration I have ever seen for the following:
1. Flight crew will not be happy with missiles stowed in the cabin and aimed at the back of their heads during missions.
2. In an emergency at low level it will be difficult to jettison the weapons to reduce weight and/or get rid of things that go boom before impacting the ground.
3. Unlike Airwolf this configuration looks impossible to deploy symmetrically or asymmetrically at high speeds due to high drag and having gaping holes in the side of the cabin. Anything loose in the cabin will end up going through the pusher.
4. The pusher is directly aft of the weapons and will be impinged face on by the back blast of the missiles. Good way to get things blown off.
From a practical point of view, I am certain that number three is the most pressing. Self FOD is a poor idea, so a procedural 'clean up' has to be implemented or what you suggest will for darned sure happen at least once. Humans are humans, right?
As to number 4, I suspect that the weapons rack can include a CAD type thing that pushes the munition down before the rocket engine fires. But I agree with you that this issue must be addressed by the FARA team.
WTF, I agreed with The Sultan? That means that I am buying the next round!
Lone wrote:
On the pushing down this is hard successfully for an aircraft that lives nap of earth.
As to storage of the missiles in the cabin I recommend Holland's "Big Week" about the bombing campaign in Europe (one of, if not the best on the subject). It includes numerous examples on how bombers just vanishing after their load explodes and how devastated the other crews were witnessing it. Sure fortified their belief they would not make it to their going home mission count. Not exactly a moral builder.
I suspect that the weapons rack can include a CAD type thing that pushes the munition down before the rocket engine fires.
As to storage of the missiles in the cabin I recommend Holland's "Big Week" about the bombing campaign in Europe (one of, if not the best on the subject). It includes numerous examples on how bombers just vanishing after their load explodes and how devastated the other crews were witnessing it. Sure fortified their belief they would not make it to their going home mission count. Not exactly a moral builder.