US Navy’s UCLASS / CBARS / MQ-XX / MQ-25 Stingray Program

[Mike Pryce]

Would it have changed the 1154 picture had the ski-jump been invented earlier?

Although, looking at the evolution of the HS.1154RN, what's clearly happening is this...

"It works better with the twin engines, old boy - but since we're using the catapult and arrester hook anyway, do we still need those funny moving bits on the engine? We could blow the flaps, like the Bucc. And shouldn't we look at the J79 while we're at it? Might cost less than RR wants to charge us..."

Hawker never thought the RN version was a 'goer', but the golden rule... Twin Spey was inspired by RR political pressure. Hawker were clear the single BS100 version was preferred, and that was the only one submitted formally. Vectored thrust allowed a smaller wing, optimised for high speed cruise, which saved weight and needed no complex lift enhancing devices. Also allowed smaller ships to be used. RN wanted big new carriers, RR needed more work. Phantom was the interim answer, plus notional VG wonder plane for the future. Notional wonder planes always are!

Ski-jump depends on the nose gear. The Harrier got lucky and had the right one already.

A-6 used limited vectoring, and well aft of the CG, so pitching moments had to be limited. All the complexity, limited benefit.

 

[sferrin]

Wouldn't the last couple pages fit better in an 1154 specific topic? ???

 

[AeroFranz]

Yes, we went off the deep end
Interesting conversation though.

 

[Mike Pryce]

Yes, we went off the deep end
Interesting conversation though.

It's all about avoiding the deep end, whether a flying fuel truck or a jump jet.

 

[NeilChapman]

Yes, we went off the deep end
Interesting conversation though.

It's all about avoiding the deep end, whether a flying fuel truck or a jump jet.

Good one. Definitely want to avoid that deep end.

 

[Sundog]

I thought Boeing was supposed to do a big MQ-25 reveal today? Or was that limited non-event of a partial forward view they put out a couple of days ago their "big" reveal? Pfft.

 

[Flyaway]

I thought Boeing was supposed to do a big MQ-25 reveal today? Or was that limited non-event of a partial forward view they put out a couple of days ago their "big" reveal? Pfft.

That was it for now. More next year at some point.

 

[autoeac]

I wonder if anyone has looked at a dedicated F/A 18 for this role. Engineer more tankage into it and you have near the same capability at a fraction of the cost plus the same engines and footprint.

 

[Colonial-Marine]

I wonder if anyone has looked at a dedicated F/A 18 for this role. Engineer more tankage into it and you have near the same capability at a fraction of the cost plus the same engines and footprint.

I don't think that's very feasible. To the best of my knowledge it (and most fighters for that matter) simply aren't good platforms to make a tanker from. You could slap EFTs on and it might help somewhat but the MQ-25 will be better.

Is there intention to use the MQ-25 in any other roles at the moment?

 

[totoro]

The general shape is kinda clear now, the butterfly tail seem most likely at this point... but where the heck is the intake? Or intakes?

 

[TomS]

The general shape is kinda clear now, the butterfly tail seem most likely at this point... but where the heck is the intake? Or intakes?

On the upper fuselage ahead of the wing. You can see a black square marked with "DANGER JET INTAKE" warnings on the top side of the fuselage at about the 5-second mark. Must be pretty close to a submerged inlet as in Tacit Blue.

 

[sferrin]

There's a picture at the top of page 55 of this topic.

 

[TomS]

There's a picture at the top of page 55 of this topic.

Right, but the old pic has a big inlet that isn't visible in the actual vehicle. It now seems to be totally submerged in the upper surface.

 

[sferrin]

There's a picture at the top of page 55 of this topic.

Right, but the old pic has a big inlet that isn't visible in the actual vehicle. It now seems to be totally submerged in the upper surface.

I don't think the inlet in the old picture protrudes. It's just the angle that's making it look like it is. I think when we see it with the inlet cover removed the inlet will be a "notch" in a curved surface rather than flush like Tacit Blue. More like Bird of Prey.

 

[TomS]

I see what you're saying, but that "notched" inlet that takes a piece out of the fuselage side isn't consistent with the markings. The JET INLET warning runs in a straight line just below the curve where the top meets the sides. If the real inlet looked like the ones in those paintings, it would cut through the JET INTAKE warning label.

 

[sferrin]

I see what you're saying, but that "notched" inlet that takes a piece out of the fuselage side isn't consistent with the markings. The JET INLET warning runs in a straight line just below the curve where the top meets the sides. If the real inlet looked like the ones in those paintings, it would cut through the JET INTAKE warning label.

I guess we'll just have to wait and see. I'd thought I heard the inlet on Tacit Blue was particularly bad, and not something I'd think they'd want to duplicate.

 

[LowObservable]

The top line at 0:02 looks completely flat.

I'm sure they know what they're doing... ;D

 

[TomS]

I guess we'll just have to wait and see. I'd thought I heard the inlet on Tacit Blue was particularly bad, and not something I'd think they'd want to duplicate.

Only on the ground, apparently. Having two engines feeding off one inlet caused starting problems (asymmetric airflow and so forth). In flight, the inlet was OK, it was the rest of the airframe that sucked.

I'm not sure if the Boeing MQ-25 is single or twin engine, so it may not have the same engine issues. Or they may have solved them with better engines or a better inlet.

 

[Mat Parry]

A bold choice considering the the angles of attack and instant power requirements for carrier landings (especially with low observables removed from the requirements).

But hey, with all of Boeing's recent tanker experience, what could possibly go wrong... :-[

 

[sferrin]

A bold choice considering the the angles of attack and instant power requirements for carrier landings (especially with low observables removed from the requirements).

But hey, with all of Boeing's recent tanker experience, what could possibly go wrong... :-[

Not to mention their stealth experience.

 

[Sundog]

Dorsal inlets don't really present a problem until you get to very high alpha and high yaw angles with the main issue being vortex ingestion. Most of the airframe manufacturers don't have an issue with it today, as modern engines are much more resistant to disturbed airflow and the inlets are generally far enough forward and operate at low enough alpha (under approximately twenty degrees of alpha) that there usually isn't a problem with vortex ingestion.

The only problem I could see is what Tom mentioned, but there are ways to mitigate the two engines one inlet problem. It seems to have been fine on the B-2, but I don't have information one way or another in that regard. When I was in school, the main problem with a single inlet for two engines tended to be with supersonic inlets, in that if you had an inlet unstart in one engine it could cause an unstart in the other.

 

[sferrin]

Dorsal inlets don't really present a problem until you get to very high alpha and high yaw angles with the main issue being vortex ingestion. Most of the airframe manufacturers don't have an issue with it today, as modern engines are much more resistant to disturbed airflow and the inlets are generally far enough forward and operate at low enough alpha (under approximately twenty degrees of alpha) that there usually isn't a problem with vortex ingestion.

The only problem I could see is what Tom mentioned, but there are ways to mitigate the two engines one inlet problem. It seems to have been fine on the B-2, but I don't have information one way or another in that regard. When I was in school, the main problem with a single inlet for two engines tended to be with supersonic inlets, in that if you had an inlet unstart in one engine it could cause an unstart in the other.

The XB-70 had THREE engines for each inlet. ;D

 

[sferrin]

The top line at 0:02 looks completely flat.

I'm sure they know what they're doing... ;D

Yeah, looking at these shots I think I have to concede it's a flush inlet on the top. I wonder if that small inlet towards the front is a cooling inlet or if it maybe does something downstream to make the flush inlet more efficient.

 

[Dragon029]

If you look carefully at the top left of this screenshot you can see some odd curvature on the paintwork, which might be part of the intake's opening.

 

[DrRansom]

Does the MQ-25 program require low-observability or a low-observable design? The Boeing aircraft is clearly intended to be more than a little stealthy... Maybe Boeing thinks that the Navy won't pass up this chance to get a stealth UAV onto the carrier deck.

As for the overall planform, does anyone know why there is such a long body ahead of the wings? What principle would leave Boeing to do that? Though, Boeing is hiding everythign about the aircraft's aft.

 

[raptor82]

I guess we'll just have to wait and see. I'd thought I heard the inlet on Tacit Blue was particularly bad, and not something I'd think they'd want to duplicate.

Only on the ground, apparently. Having two engines feeding off one inlet caused starting problems (asymmetric airflow and so forth). In flight, the inlet was OK, it was the rest of the airframe that sucked.

I'm not sure if the Boeing MQ-25 is single or twin engine, so it may not have the same engine issues. Or they may have solved them with better engines or a better inlet.

FAA registry says "single engine" :

http://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=234MQ

 

[Moose]

Does the MQ-25 program require low-observability or a low-observable design? The Boeing aircraft is clearly intended to be more than a little stealthy... Maybe Boeing thinks that the Navy won't pass up this chance to get a stealth UAV onto the carrier deck.

As for the overall planform, does anyone know why there is such a long body ahead of the wings? What principle would leave Boeing to do that? Though, Boeing is hiding everythign about the aircraft's aft.

Things have been fairly fluid in this program, but there has been a stated desire for the MQ-25 to use an airframe that can gain stealthy/LO features for follow-on variants after the tanker is in hand.

 

[Flyaway]

This article does some analysis on the design. As it points out it’s almost as interesting to note what we don’t get shown as to what we do.

http://www.thedrive.com/the-war-zone/17336/new-details-emerge-in-boeings-first-video-of-its-carrier-based-tanker-drone

 

[JeffTracy]

@Boeing UCLASS grows a tail, loses an intake - adapted from BDS CEO Chris Chadwick's May 21 investor-day presentation

Link: www.twitter.com/TheWoracle/status/469479264321277952/photo/1


The intake is still there, just not visible in this picture. :
I presume, it is on top of the fuselage. A NACA duct like on stealthy cruise missile???

Looks like this design dates from UCLASS days when there was a greater emphasis on LO.
Also noticeable is the shallow angle of the V tails reminiscent of the McDD JSF.
Maybe the angle of the photo but the undercarriage looks strangely close to the leading edge. If this was rumour forum I might even say Hansa-jet like.

 

[Dragon029]

Does the MQ-25 program require low-observability or a low-observable design? The Boeing aircraft is clearly intended to be more than a little stealthy... Maybe Boeing thinks that the Navy won't pass up this chance to get a stealth UAV onto the carrier deck.

As for the overall planform, does anyone know why there is such a long body ahead of the wings? What principle would leave Boeing to do that? Though, Boeing is hiding everythign about the aircraft's aft.

As far as I'm aware there's no requirement for low observability, but there'll likely still be some weighting for it as an 'extra feature / capability'. Ultimately, both General Atomics and Lockheed's MQ-25 proposals use external pylon-mounted AAR pods which isn't very conducive to LO, so chances are that the final winning MQ-25 won't exactly be a VLO platform unless it's flown clean or with an internal sensor / weapons payload. Right now the Boeing proposal doesn't appear to have any internal bays, but perhaps that could change with an upgraded variant down the line.

As for the long body - you need space for a satellite uplink, plus to have that recessed intake on top you want an intake ramp that has a relatively long and smooth transition. The longer the fuselage the more stable you are in pitch as well, which will be important for carrier landings.

This article does some analysis on the design. As it points out it’s almost as interesting to note what we don’t get shown as to what we do.

http://www.thedrive.com/the-war-zone/17336/new-details-emerge-in-boeings-first-video-of-its-carrier-based-tanker-drone

Something pointed out in that article that I missed the first time around is the bump around the wing-fold mechanism (on the right of the attached image).

Perhaps Boeing plans to gain an advantage over their competitors by having their AAR pods mounted far out on the wings (necessitating bulkier wing-fold mechanisms), potentially enabling the simultaneous refueling of 2 fighters? It'd be neat if that bump housed the hose and drogue internally behind a door, but I doubt that's the case.

 

[Hood]

I wonder if a new LO refuelling pod will be developed?

Also, wouldn't have a completely flush intake, perhaps with a long internal ramp, sacrifice internal volume required for fuel tankage?

 

[Flyaway]

More analysis here of its LO features and why it may still have them even though they are seemingly not required.

Why Does Boeing's MQ-25 Prototype Look So Stealthy?

A short teaser video posted by Boeing on Twitter showing the company-funded prototype of its offering for the U.S. Navy’s MQ-25 Stingray has raised questions about why its design for an unmanned carrier-based aerial refueling tanker should look so stealthy.

http://m.aviationweek.com/blog/why-does-boeings-mq-25-prototype-look-so-stealthy?

 

[Sundog]

It's been well known/stated that the USN would also like to use the airframe for some ISR roles in the future. So you design it to become stealthy, but you don't have to use the higher cost materials, etc, for the tanker version to keep costs down. Although, I'm sure some manufacturing costs are higher as a result, but if the difference is a few percent, then it's probably worth it to gain more capability later.

 

[sublight_]

More analysis here of its LO features and why it may still have them even though they are seemingly not required.

Why Does Boeing's MQ-25 Prototype Look So Stealthy?

Maybe it was Boeing's RQ-180 entry?

 

[Airplane]

More analysis here of its LO features and why it may still have them even though they are seemingly not required.

Why Does Boeing's MQ-25 Prototype Look So Stealthy?

Maybe it was Boeing's RQ-180 entry?

Not likely. It costs more to produce to a stealthy air vehicle versus one without signature reductions. There is zero reason to use a mere design study of a stealthy vehicle and recycle it and then produce it for a non-stealthy mission. More than likely this vehicle was built with the intent of performing more than merely refueling 18s and 35s. Too small for a weapons bay to hold more than a couple SDBs (I don't even see a small weapons bay), so perhaps it will be a battlefield target finder as well.

 

[sublight_]

There is zero reason to use a mere design study of a stealthy vehicle and recycle it and then produce it for a non-stealthy mission.

But isn't that exactly what X-47B was? It had all the stealth shaping but none of the actual RCS reduction enhancements in place.

 

[marauder2048]

It's been well known/stated that the USN would also like to use the airframe for some ISR roles in the future. So you design it to become stealthy, but you don't have to use the higher cost materials, etc, for the tanker version to keep costs down. Although, I'm sure some manufacturing costs are higher as a result, but if the difference is a few percent, then it's probably worth it to gain more capability later.

Some of the more recent Navy slideware (this is from RADM Darrah's presentation from Aug 2017) suggests they
haven't abandoned the strike aspect in their vision for MQ-25.

 

[Flyaway]

It's been well known/stated that the USN would also like to use the airframe for some ISR roles in the future. So you design it to become stealthy, but you don't have to use the higher cost materials, etc, for the tanker version to keep costs down. Although, I'm sure some manufacturing costs are higher as a result, but if the difference is a few percent, then it's probably worth it to gain more capability later.

Some of the more recent Navy slideware (this is from RADM Darrah's presentation from Aug 2017) suggests they
haven't abandoned the strike aspect in their vision for MQ-25.

There might be some advantage to making their primary shipboard refueller fairly stealthy as well. Especially if it has to operate in certain more contested environments.

 

[jsport]

Boeing appears to have a barely hybrid wing with mostly dragging nearly verticals and fuselage. Not optimum.

Current technology and diligence would build an max endurance/payload BWB 'complete airplane'. (not a 'flying wing' which is unstable on landing w/ a full tank on a carrier.)

 

[sferrin]

Current technology and diligence would build an max endurance/payload BWB 'complete airplane'. (not a 'flying wing' which is unstable on landing w/ a full tank on a carrier.)

Lockeed calls it a Hybrid Wing Body design.