Moderators: richierich, ua900, PanAm_DC10, hOMSaR
aschachter wrote:Interesting that the USAF is trying this again.
I remember reading about this aircraft once, the USAF's earlier attempt at supersonic VTOL.
https://en.wikipedia.org/wiki/Rockwell_XFV-12
China's helicopter makers have reportedly conducted test flights for at least two types of helicopters with innovative designs: one is a blended-wing body multi-rotor vertical takeoff and landing aircraft, the other is a helicopter with a completely different, innovative design
kitplane01 wrote:I'm sure you know several of us fear the operational cost is not worth the additional benefit.
kitplane01 wrote:What I'm asking now is somewhat technical so maybe no one knows .. when are estimates of running costs created? Surely they don't spend many billions of $$ on multiple prototypes before deciding they can afford to run the thing. So how does that happen?
Over 3,000 American soldiers or contractors were killed in fuel supply convoys between 2003 and 2007 in Iraq and Afghanistan, officials said. Eighty percent of all supply trucks operating in the region are carrying fuel.
kitplane01 wrote:I was actually just curious at what point in the development process the operational affordability decision is made. I've read a lot about defense procurement and never read about that.
RJMAZ wrote:kitplane01 wrote:I was actually just curious at what point in the development process the operational affordability decision is made. I've read a lot about defense procurement and never read about that.
Multiple studies have already been done.
You will really enjoy the following link
https://dsb.cto.mil/reports/2000s/ADA473069.pdf
Page 68 has the costs.
Costs for a 30t payload tilt rotor in 2007 dollars.
$750 million R&D
$1.5 billion for new engine development
$2.5 billion for two prototypes
$190 million per aircraft with 100 aircraft ordered
The MVM estimates $250 million per aircraft. So we are looking at more than double and close to triple the cost of the C-130J.
The analysis even calculates the sustainment levels for battalions in combat to work out the number of VTOL aircraft are required. It directly compares it to the C-130 with runway construction in what they call an "enclave landing zone" or what we call a FOB.
Most of the concerns in the report regarding technical, reliability, safety and development risk have since been eliminated. The V-22 has proven itself. The V-280 development was fairly rapid.
RJMAZ wrote:[...]
Most of the concerns in the report regarding technical, reliability, safety and development risk have since been eliminated.
[...]
kitplane01 wrote:We're arguing that if you cannot maintain a FOB you're already losing the war.
kitplane01 wrote:And the solution might often be more soldiers to keep the peace, not more tiltrotors to fly over the territory we fail to control.
RJMAZ wrote:kitplane01 wrote:We're arguing that if you cannot maintain a FOB you're already losing the war.
A country can win a war and still suffer high casualties at their FOB. The whole point of heavy vertical lift is to reduce casualties. 3000+ fuel truck convoy drivers deaths is a start.
You're not arguing against me but the high quality research and plans of the US military. Page 19 shows the operational geometry. Intermediate supply bases contain all of the logistics but are located in a safe area. Battlefield enclaves do all the hard work done by a traditional FOB. No capability is lost.kitplane01 wrote:And the solution might often be more soldiers to keep the peace, not more tiltrotors to fly over the territory we fail to control.
That shows that you completely miss the point. The whole point of that document is to improve the US effectiveness again asymmetric adversaries, distributed war, insurgency and terrorism.
If territory can't be controlled it would just get bombed by the air. So the fact they are talking about soldiers on the ground means this is about controlling territory and reducing casualties.
50 soldiers tasked to protecting 100,000 litres of highly explosive jet fuel at a FOB contribute nothing to keeping the peace. Move that fuel to the ISB.
RJMAZ wrote:It seems China also has a high speed VTOL program.China's helicopter makers have reportedly conducted test flights for at least two types of helicopters with innovative designs: one is a blended-wing body multi-rotor vertical takeoff and landing aircraft, the other is a helicopter with a completely different, innovative design
https://www.globaltimes.cn/page/202204/1259635.shtml
Another popular theory, pushed by the nationalist tabloid the Global Times, attempts to connect the virus's origins to a US coronavirus expert, Dr Ralph Baric, and researchers at Fort Detrick.
The newspaper suggested that Dr Baric created a new human-infecting coronavirus, citing a paper the North Carolina-based researcher co-authored about the virus's transmission from bats in Nature Medicine.
bajs11 wrote:
[...]
You do know that the Global Times is a CCP nationalist daily newspaper.
https://en.wikipedia.org/wiki/Global_Times
They've been spreading all kind of misinformation from covid-19 to Xinjiang to HK protests to the ongoing war in Ukraine.
[...]
RJMAZ wrote:One thing the US is good at is predicting the future. The US has the guts to cancel expensive programs when it no longer suits the future B-2, F-22, Commanche, FCS, LCS, Zumwalt etc. They will presist with troubled
flyinggoat wrote:This might sound crazy, but how feasible would it be to use the F35B engine and lift fan for these larger VTOL projects? Maybe a blended wing body aircraft with two, four, or even six (depending on size) F35B engines and lift fans would be feasible.
The MTOW of a F35B is 60,000lbs.
The MTOW of a C130J is 155,000lbs.
At first glance, a C130 size aircraft with four F35B engines and lift fans would appear to provide more than enough lift, possibly even with an engine or lift fan failure.
Ok, maybe far fetched, but at the same time, why not? A blended wing body with four F35B engines and lift fans in the wings sure would be neat. Much cheaper than developing a whole new lift system too.
kitplane01 wrote:We super-a-whole-bunch don't see the world the same way.
You REALLY believe the LCS was cancelled when they understood it was a bad idea?
Did you know there are still 11 ships under construction and/or waiting to be commissioned?
https://en.wikipedia.org/wiki/Littoral_ ... mbat_ships
RJMAZ wrote:[...]
The Bell concept is effectively a tilt rotor.
[...]
RJMAZ wrote:kitplane01 wrote:We super-a-whole-bunch don't see the world the same way.
You REALLY believe the LCS was cancelled when they understood it was a bad idea?
Did you know there are still 11 ships under construction and/or waiting to be commissioned?
https://en.wikipedia.org/wiki/Littoral_ ... mbat_ships
The LCS is a favourite punching bag. They were developed for littoral operations with a very shallow draft around 4 metres. South east asia has lots of islands and shallow waters. They are around half the draft of the new Constellation-class frigates. China has simply transitioned from a green water navy to a blue water navy much quicker than anyone expected. Had war started in 2015 the US Navy would have wished for 100 LCS.
RJMAZ wrote:kitplane01 wrote:We super-a-whole-bunch don't see the world the same way.
You REALLY believe the LCS was cancelled when they understood it was a bad idea?
Did you know there are still 11 ships under construction and/or waiting to be commissioned?
https://en.wikipedia.org/wiki/Littoral_ ... mbat_ships
The LCS is a favourite punching bag. They were developed for littoral operations with a very shallow draft around 4 metres. South east asia has lots of islands and shallow waters. They are around half the draft of the new Constellation-class frigates. China has simply transitioned from a green water navy to a blue water navy much quicker than anyone expected. Had war started in 2015 the US Navy would have wished for 100 LCS.
By your logic the F-22 is a terrible aircraft. They couldn't cancel it fast enough. F-15's will still be flying long after the F-22 is retired. When the F-22 started production the chance of a near peer war suddenly dropped to zero. The role of the aircraft had just been made redundant for a couple decades. Same with the LCS.
IADFCO wrote:RJMAZ wrote:[...]
The Bell concept is effectively a tilt rotor.
[...]
If you refer to the full flight envelope, i.e., hover plus forward flight, it's most definitely not.
kitplane01 wrote:So, answer the question if you want. Do you believe the LCS was cancelled at the right time? There are still 11 building/on-order/waiting-to-be-commissioned.
744SPX wrote:Sikorsky ought to revisit the X-wing concept that they investigated with the S-72. It would be less draggy, have far superior disk loading, and capable of higher speeds than Bell's folding rotors concept.
https://www.sikorskyarchives.com/X-WING.php
This is Sikorsky's to lose if they go this route.
IADFCO wrote:The problem with the X-wing concept was (and is) its extreme complexity.
The airfoils by itself had no trailing edge in the conventional sense. The trailing edge was "recreated" by the airflow pumped through one or both the blade/wing spanwise slots (this was the concept proposed by Prof. Cheeseman) by the Coanda effect, i.e., the airflow sticking to and following a solid surface under certain conditions.
This airflow would have come from and be regulated by (from a caption in the interesting link provided by @744SPX) a circulation control valving system consist[ing] of 48 valves, 24 for leading edge blowing and 24 for the trailing edge. Note the size of the plenum hardware in relation to the technician working on it. It also required a very complex control system to precisely synchronize the airflow in the presence of centrifugal pumping and Coriolis effects. This complicated system was partially fixed (to the aircraft) and partially rotating, which means that some of the seals also had to be rotating.
As a laboratory/research experiment it was fascinating, and it was fantastic that NASA and Sikorsky spent the time and money to study it. As a practical solution IMHO it was doomed to failure. The maintenance effort required to keep the slots on the wing clean and the hub valving system operational must have been staggering, especially because both would have probably been flight critical.