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Author Topic: US Navy’s UCLASS / CBARS / MQ-XX / MQ-25 Stingray Program  (Read 137888 times)

Offline NeilChapman

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Re: US Navy’s UCLASS / CBARS / MQ-XX / MQ-25 Stingray Program
« Reply #645 on: October 07, 2017, 06:02:38 pm »
blended wing bodies are always going to be better at carrying payloads as well as steath and high dynamic maneuver. Tube and wing is 'Model A' and has been for decades

Personally, I think an X-47-ish or LM HWB design, sized for a maximum takeoff of 80,000lbs would be the best.

I like the design, the efficiency of it.  Perhaps a "scaled" solution for the Navy then, potentially, a full-sized version for KC-Z solution.

-

Just been reading about 91 S-3's in storage.  11k hours of service life left in them and a tanker version was built that can haul 30k lbs of fuel.

Why wouldn't these fit the bill?






Offline red admiral

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Re: US Navy’s UCLASS / CBARS / MQ-XX / MQ-25 Stingray Program
« Reply #646 on: October 08, 2017, 12:21:20 am »
blended wing bodies are always going to be better at carrying payloads as well as steath and high dynamic maneuver. Tube and wing is 'Model A' and has been for decades

But probably not for operations on carriers where you need high lift devices and sufficient control power to trim them. You can't do this with a bwb and so have got to massively reduce wing loading, which then significantly impacts your cruise drag.

Just because X-47B managed to take off and land doesn't mean that there weren't significant sacrifices.

Offline AeroFranz

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Re: US Navy’s UCLASS / CBARS / MQ-XX / MQ-25 Stingray Program
« Reply #647 on: October 08, 2017, 09:01:45 am »
If you don't need all-aspect stealth, the tailless configuration is not the best choice for bringback capability. Can't trim high lift coefficients, like RA said.
All modern aircraft have four dimensions: span, length, height and politics.   TSR.2 got the first three right - Sir Sydney Camm

Offline sferrin

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Re: US Navy’s UCLASS / CBARS / MQ-XX / MQ-25 Stingray Program
« Reply #648 on: October 08, 2017, 10:27:29 am »
If you don't need all-aspect stealth, the tailless configuration is not the best choice for bringback capability. Can't trim high lift coefficients, like RA said.

LM HWB. 
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Offline AeroFranz

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Re: US Navy’s UCLASS / CBARS / MQ-XX / MQ-25 Stingray Program
« Reply #649 on: October 08, 2017, 12:18:08 pm »
The HWB can certainly trim high lift coefficients. It's my personal bias, but i'm still not sure taking a tube and wing and melding it with a BWB is necessarily better than either. Now you don't have the trim problems of a BWB, but you added back so much wetted area that it doesn't have the low drag either.
I have zero evidence to support this, but it smells a lot like a case of picking a certain configuration just because it's different from what other companies are doing. There are oodles of AIAA technical papers produced on the HWB subject, but in the end once you remove the effects of better engines (which can be applied to most of the alternatives), all these configurations end up within 5% of each other - that is, within the error margin of what you can demonstrate short of flying a prototype! I'll be curious to see what happens if and when NASA picks their X-plane demonstrators.
All modern aircraft have four dimensions: span, length, height and politics.   TSR.2 got the first three right - Sir Sydney Camm

Offline red admiral

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Re: US Navy’s UCLASS / CBARS / MQ-XX / MQ-25 Stingray Program
« Reply #650 on: October 09, 2017, 12:32:28 am »
I have zero evidence to support this, but it smells a lot like a case of picking a certain configuration just because it's different from what other companies are doing. There are oodles of AIAA technical papers produced on the HWB subject, but in the end once you remove the effects of better engines (which can be applied to most of the alternatives), all these configurations end up within 5% of each other - that is, within the error margin of what you can demonstrate short of flying a prototype! I'll be curious to see what happens if and when NASA picks their X-plane demonstrators.

Agree. You get funding to look at something different, but almost all gains are due to "technology factors" above the current day, which a conventional tube and wing can use too.

The HWB configuration is nice, but there are small gains over an advanded  tube and wing and a lot more risk. Maybe better value putting the money for a HWB demonstrator into additional subsystem technology research.

Offline sferrin

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Re: US Navy’s UCLASS / CBARS / MQ-XX / MQ-25 Stingray Program
« Reply #651 on: October 09, 2017, 04:04:20 am »
I have zero evidence to support this, but it smells a lot like a case of picking a certain configuration just because it's different from what other companies are doing. There are oodles of AIAA technical papers produced on the HWB subject, but in the end once you remove the effects of better engines (which can be applied to most of the alternatives), all these configurations end up within 5% of each other - that is, within the error margin of what you can demonstrate short of flying a prototype! I'll be curious to see what happens if and when NASA picks their X-plane demonstrators.

Agree. You get funding to look at something different, but almost all gains are due to "technology factors" above the current day, which a conventional tube and wing can use too.

The HWB configuration is nice, but there are small gains over an advanded  tube and wing and a lot more risk. Maybe better value putting the money for a HWB demonstrator into additional subsystem technology research.

A HWB or BWB has a lot more volume than a tube and wing for a given footprint.  That's important on a carrier.
"DARPA Hard"  It ain't what it use to be.

Offline bobbymike

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Offline jsport

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Re: US Navy’s UCLASS / CBARS / MQ-XX / MQ-25 Stingray Program
« Reply #653 on: October 11, 2017, 03:13:34 pm »
Claiming H/BWB have trim problems on landing is either design laziness in the 21st century or outright defense of inferior tube and wing designs. 

Dipping a H/BWB wing into the wind assists quicker cleaner landing w/ no crosswind rolling effect but rather an accelerated stable landing (Assuming the landing gear works.) while a T & W aircraft have perpendicular crosswinds rolling the tube not in the direction of landing,

Defending T&W is mumbo jumbo.

Offline NeilChapman

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Re: US Navy’s UCLASS / CBARS / MQ-XX / MQ-25 Stingray Program
« Reply #654 on: October 11, 2017, 10:44:57 pm »


Redid my numbers.

MQ-25 w/15k lbs of give @ 500 nmi. would increase range of a flight of 4 Super Hornets by 400 nmi - 200 out and 200 back when 3-480 gal tanks are carried.  W/Block III CFT's you could add an additional 200 nmi to range, opening up a 300 nmi. gap between the bad guys and MQ-25's. 

Navy's going to want more than 5 MQ-25's per deck.  Have there been any quantities mentioned?




Offline red admiral

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Re: US Navy’s UCLASS / CBARS / MQ-XX / MQ-25 Stingray Program
« Reply #655 on: October 12, 2017, 03:56:12 am »
Claiming H/BWB have trim problems on landing is either design laziness in the 21st century or outright defense of inferior tube and wing designs. 

Dipping a H/BWB wing into the wind assists quicker cleaner landing w/ no crosswind rolling effect but rather an accelerated stable landing (Assuming the landing gear works.) while a T & W aircraft have perpendicular crosswinds rolling the tube not in the direction of landing,

Defending T&W is mumbo jumbo.

Basic First Order Effects

Deploying flaps on a wing significantly increases Clmax so you can get away with higher wing loading for same Take-Off/Landing Performance. Deploying flaps also gives a large pitching moment, which is trimmed out with a separate control surface. You cannot do this on a configuration that doesn't have a separate pitch control device e.g. a BWB which results in you having to adopt an oversized wing or accept higher take-off/landing speeds to generate more lift.

This isn't anything to do with problems - these are basic design choices

Offline sferrin

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Re: US Navy’s UCLASS / CBARS / MQ-XX / MQ-25 Stingray Program
« Reply #656 on: October 12, 2017, 04:56:48 am »
Claiming H/BWB have trim problems on landing is either design laziness in the 21st century or outright defense of inferior tube and wing designs. 

Dipping a H/BWB wing into the wind assists quicker cleaner landing w/ no crosswind rolling effect but rather an accelerated stable landing (Assuming the landing gear works.) while a T & W aircraft have perpendicular crosswinds rolling the tube not in the direction of landing,

Defending T&W is mumbo jumbo.

Basic First Order Effects

Deploying flaps on a wing significantly increases Clmax so you can get away with higher wing loading for same Take-Off/Landing Performance. Deploying flaps also gives a large pitching moment, which is trimmed out with a separate control surface. You cannot do this on a configuration that doesn't have a separate pitch control device e.g. a BWB which results in you having to adopt an oversized wing or accept higher take-off/landing speeds to generate more lift.

This isn't anything to do with problems - these are basic design choices

HWB  Think of it as a "tube and wing" with built-in CFTs.
"DARPA Hard"  It ain't what it use to be.

Offline jsport

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Re: US Navy’s UCLASS / CBARS / MQ-XX / MQ-25 Stingray Program
« Reply #657 on: October 12, 2017, 10:49:17 am »
Claiming H/BWB have trim problems on landing is either design laziness in the 21st century or outright defense of inferior tube and wing designs. 

Dipping a H/BWB wing into the wind assists quicker cleaner landing w/ no crosswind rolling effect but rather an accelerated stable landing (Assuming the landing gear works.) while a T & W aircraft have perpendicular crosswinds rolling the tube not in the direction of landing,

Defending T&W is mumbo jumbo.

Basic First Order Effects

Deploying flaps on a wing significantly increases Clmax so you can get away with higher wing loading for same Take-Off/Landing Performance. Deploying flaps also gives a large pitching moment, which is trimmed out with a separate control surface. You cannot do this on a configuration that doesn't have a separate pitch control device e.g. a BWB which results in you having to adopt an oversized wing or accept higher take-off/landing speeds to generate more lift.

This isn't anything to do with problems - these are basic design choices

An unmanned carrier tanker is already projected with lesser wingspan than a manned carrier craft. Catapults speed takeoff and hooks stop/slow craft on deck. Exact flaps are design considerations for carrier and... When the whole craft is maximizing lift while minimizing drag having a time on BWB having to larger than a T&W..

Are we arguing WWI aircraft designs like Raven and Puma are reasonable designs in the 21st century. They are dinosaur's that folks are telling us are BMWs.

Offline red admiral

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Re: US Navy’s UCLASS / CBARS / MQ-XX / MQ-25 Stingray Program
« Reply #658 on: October 12, 2017, 12:02:06 pm »
What on earth are you on about jsport? Your comments don't even begin to make sense to me. Please could you explain more clearly.

Offline AeroFranz

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Re: US Navy’s UCLASS / CBARS / MQ-XX / MQ-25 Stingray Program
« Reply #659 on: October 12, 2017, 06:15:03 pm »
 ??? if bringback capability is something you care about, then trimmed CLmax is definitely something you try to maximize. Regardless of catapults and arresting wires, there is a combination of weights and airspeed limits that you can't exceed. High CLmax helps with both.
The trim power conferred by a horizontal tail acting at a long moment arm is hard to match by something that has little of either.

I'm no tube and wing zealot, i like exotic configurations as much as anyone else on this forum. But there's a reason 98% of all airplanes have that layout. It works. And it's not for lack of trying that other configurations haven't been adopted.
All modern aircraft have four dimensions: span, length, height and politics.   TSR.2 got the first three right - Sir Sydney Camm