DARPA/SOCOM Speed and Runway Independent Technologies (SPRINT)

yasotay said:
The fan in wing drastically improves the flexibility to the logisticians and operational commanders with its fixed wing range, speed, with the flexibility of landing sites too. It does not however solve the CSAR/Medical Evacuation and to a lesser extent a set of the Special Operations missions.
The issue, I believe that while the fan in wing will likely not have the downwash velocities of a Harrier or F-35, I believe it would have greater down wash velocities than some of the missions called for. Higher than the current M/CV-22B. The Ospreys down wash velocity is already considered at the edge of viability for safe operations away from prepared surfaces. Certainly, the ability to land at much lower speeds on unimproved surfaces compared to a C-130 for instance, is a significant enhancement. However, mission sets that require prolonged VTOL, such as fast rope or foliage penetrator for CSAR seem very high risk. VTOL landing to small unimproved restrictive landing areas likewise would seem exceedingly high risk. This is more pronounce in those terrains where the bearing ratio of the land is that of a plowed field or less. While VTOL aircraft can overcome this challenge by maintaining hover and not putting the full weight on the landing gear, anything much higher velocity than the Osprey will likely begin to sling dirt and rocks in doing this. If I recall correctly there was a bit of Harrier lore from BAOR days about them "digging their own grave" on unimproved terrain and that the RAF had very effective engineers who could quickly establish "semi-improved" landing sites. While this might be a viable methodology still, I suspect that the ubiquitous ISR of our information age makes this higher risk. Roads and car parks in the parts of the world most likely to see this sort of operation tend to be high traffic volume areas, further exacerbating the observation challenge.
The ability of the fan in wing platform to move significant (C-130 sized loads[?]) over larger distances and perform VSTOL to roads and car parks is a drastic improvement over current runway dependent aircraft. I certainly hope to see the successful development of this concept for those reasons. I just do not see it fulfilling all of the mission sets that I have seen put forward for this HSVTOL program.
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I think CSAR is going to be limited to V-22s and V-280s for a long time.
 
yasotay said:
….. If I recall correctly there was a bit of Harrier lore from BAOR days about them "digging their own grave" on unimproved terrain and that the RAF had very effective engineers who could quickly establish "semi-improved" landing sites. ….
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The RAF liked to lay pressed steel plates to “improve”’short-term forward operating bases for Harriers.
During the Falklands War, they built a PSP landing strip over-looking Falkland Sound. There is a video of a Harrier approaching the PSP in a slow, forward hover. It’s down-wash inflated a few sections of PSP and peeled them upwards. The forward operating strip was “shortened” for a few weeks until engineers could replace the damaged PSP.
So PSP is a huge improvement for forward airstrips, but not available for landing near targets forward of your front line.
 
What happened to LM Various and of which effort was it part of?
 
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Sea state is calm, wind is fair but the offset in landing is over a meter. I doubt that this is quite a positive result.
(targeting point is defined by the QR code).
 
TomcatViP said:
Sea state is calm, wind is fair but the offset in landing is over a meter. I doubt that this is quite a positive result.
(targeting point is defined by the QR code).
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I disagree. They put the camera right on the back edge of the QR code target. That's not a huge miss by any reasonable standard.
 
www.aurora.aero

A Revolutionary Solution for Contested Air Transport - Aurora Flight Sciences

Fan-in-wing technology powers Aurora’s concept for unprecedented speed and stealth in a vertical lift platform.
www.aurora.aero www.aurora.aero

The team is currently designing an uncrewed demonstrator with a 45-ft wingspan and 1,000-pound payload capacity for the SPRINT program. The propulsion system includes off-the-shelf turbofan and turboshaft engines that would power the vehicle to a maximum of 450 knots true airspeed (KTAS).

The technology demonstrated in the SPRINT X-plane could be scaled to medium and heavy lift aircraft, creating a future family of systems. For example, Aurora envisions a manned, 130-ft wingspan aircraft with four lift fans and 40-ft payload bay. The FIW aircraft could meet or exceed the payloads, ranges, and speeds typical of fixed wing military transport aircraft while delivering the tactical advantage of true vertical takeoff and landing.
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raptor82 said:
www.aurora.aero

A Revolutionary Solution for Contested Air Transport - Aurora Flight Sciences

Fan-in-wing technology powers Aurora’s concept for unprecedented speed and stealth in a vertical lift platform.
www.aurora.aero www.aurora.aero
Click to expand...
If it demonstrates payload/range/speed superior to a typical fixed-wing military transport, a CTOL derivative might be a possibility. On the other hand, the BWB airframe might not be big enough to take advantage of increased payload provided by removal of the lift systems and CTOL operations. The impracticality of stretching a BWB airframe is one of the configuration's downsides.
 
Barring a semi-successful CTOL or STOL version, I don't really see the US military buying a lot of these. Replacing AFSOC's MC-130s, yes. Replacing all the C-130s? No.
 
I could be wrong, but in this case, I am not sure that this propulsion methodology is going to land in fields any more than an F-35 or Harrier. It is still of significant benefit to be able to operate away from airfields.
 
yasotay said:
I could be wrong, but in this case, I am not sure that this propulsion methodology is going to land in fields any more than an F-35 or Harrier. It is still of significant benefit to be able to operate away from airfields.
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For the vertifan at least, the downwash was much more benign than either a harrier or F-35 - you wouldn't have someone walking under either of those in a hover!

View: https://youtu.be/zbXVjx_kqu8


At t=3:20 & 12:00 you can see a ground crewman walk under a hovering vertifan
 

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TomS said:
I disagree. They put the camera right on the back edge of the QR code target. That's not a huge miss by any reasonable standard.
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Another advantage of the quad-copter configuration is that they can shut off one or two outboard engines to improve loiter time (ala. Lockheed P-3 Orion).
 
Their website does mention being able to feather or even fold unused props in horizontal flight.
 
From the recent articles posted above it appears that Bell has done considerable work to reduce the potential parasite drag associated with the drive and folding mechanisms. As much as I am a believer in tilt rotor as a step forward in VTOL flight, I would have to think that the fan in wing competitor has an advantage if range is a primary driver. It will come down to how much 'VTOL' time and very low speed maneuvering weighs against cruise efficiency.
 
Conversion also. A fan in wing needs to manage the low speed that comes with transition. You are not going to pop the nose at near the vertical before the VTOL system take over (think at your cargo).
What that means is that your are constrained with over dimensioned wings, hence high drag during the cruise portion.
 

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