• Hi Guest! Forum rules have been updated. All users please read here.

Boeing-Sikorsky SB>1 Defiant (Model S-100)

Triton

Donald McKelvy
Senior Member
Joined
Aug 14, 2009
Messages
9,723
Reaction score
213
Website
deeptowild.blogspot.com
Are we going to create separate topics for each JMR Medium proposal?

http://www.secretprojects.co.uk/forum/index.php/topic,13812.0.html
 

TomS

CLEARANCE: Top Secret
Senior Member
Joined
Apr 16, 2008
Messages
3,264
Reaction score
149
We already have one for the Bell V-280.


http://www.secretprojects.co.uk/forum/index.php/topic,19036.msg246405.html#msg246405
 

hesham

CLEARANCE: Above Top Secret
Joined
May 26, 2006
Messages
24,136
Reaction score
1,027
VTOLicious said:
I just noticed that the Defiant still does not have its dedicated thread. Here we go!

Let's start with the latest video and some screenshots of the same:
https://youtu.be/SxSvsccwsXk

BR Michael

Nice find Michael
 

F-14D

I really did change my personal text
Senior Member
Joined
Oct 4, 2007
Messages
1,734
Reaction score
20
I note that the video is titled "Introducing the Boeing-Sikorsky SB-1 Defiant". Does this mean the designator will change to "BS"?

IT'S A JOKE!!

What happens to the Defiant if UTC spins off Sikorsky?. Sikorsky's military side looks like a natural pickup for Boeing, so it would then be the B-1. Oh wait... Boeing already has one of those.

Seriously, though, what would happen? The current DoJ would never allow that, merger or buy. Does Sikorsky standing on it own have the resources to complete their share of this program and the potential FVL follow-on?
 

TomS

CLEARANCE: Top Secret
Senior Member
Joined
Apr 16, 2008
Messages
3,264
Reaction score
149
F-14D said:
I note that the video is titled "Introducing the Boeing-Sikorsky SB-1 Defiant". Does this mean the designator will change to "BS"?

IT'S A JOKE!!

What happens to the Defiant if UTC spins off Sikorsky?. Sikorsky's military side looks like a natural pickup for Boeing, so it would then be the B-1. Oh wait... Boeing already has one of those.

Seriously, though, what would happen? The current DoJ would never allow that, merger or buy. Does Sikorsky standing on it own have the resources to complete their share of this program and the potential FVL follow-on?
Well, remember that SB-1 (or SB>1) is only the Bell-Sikorsky internal designation and has nothing to do with any eventual military designation. Which name comes first seems to depend on who wrote the rpess release.

In terms of a potential sale, I don't think we should be thinking of Sikorsky as separate military and civilian "sides." Anyone who bought the company would get both. The production of civil and military product happens in the same factory and there is considerable overlap in both production and engineering staff. A buyer might abandon future civil sales efforts, but why do that when the S-92 is mainly of interest for the offshore oil rig support market?

My hunch is that it's going to be a stand-alone company, at least for a while. No one will want to buy them until the JMR/FLV program is a little firmer than it is now.
 

yasotay

CLEARANCE: Top Secret
Senior Member
Joined
Oct 19, 2006
Messages
2,016
Reaction score
97
Actually I could see Textron making a play to acquire Sikorsky completely. It would then have almost all of the US commercial rotorcraft industry under its control and the market cannot stay soft forever. This would make Textron one of the strongest civil aviation concerns in the US. On the military side Textron would then be in a very strong position with DoD (all of the USN and USMC) and a good portion of the Army with the H-60.

I suppose that Sikorsky would stand on its own for a while, but cannot imagine its investors turning away from a buy out. If Sikorsky does not get sold outright, I think it will get ripped apart in the name of profit.
 

F-14D

I really did change my personal text
Senior Member
Joined
Oct 4, 2007
Messages
1,734
Reaction score
20
Triton said:
Lockheed Martin wouldn't buy Sikorsky?
That would depend on whether or not LM has any corporate interest in getting back into the helicopter business. Sikorsky's next big money-maker, the CH-53K, is not going to be generating substantial profits for a while yet, and beyond that the potential is on FVL (if it survives), which is by no means a sure shot if they win and even if they do it'll be daces before that starts brining in the cash. It may not be that attractive a business for LM.

If they did, though, it would be kind of ironic. Years ago Sikorsky worked hard to persuade the market that there was no need or advantage to rigid rotors (they tried the same thing with Tilt-Rotor), but now embraces them as they are essential to X2. It would be a doubly ironic case if the company they worked against ended up owning them.
 

yasotay

CLEARANCE: Top Secret
Senior Member
Joined
Oct 19, 2006
Messages
2,016
Reaction score
97
I just cannot see LM doing that. I think that there is a better chance that Textron might go for the brass ring, but sadly really think that the Grand Ol' helicopter company will get parted out by its investors in the long run.
 

F-14D

I really did change my personal text
Senior Member
Joined
Oct 4, 2007
Messages
1,734
Reaction score
20
yasotay said:
Actually I could see Textron making a play to acquire Sikorsky completely. It would then have almost all of the US commercial rotorcraft industry under its control and the market cannot stay soft forever. This would make Textron one of the strongest civil aviation concerns in the US. On the military side Textron would then be in a very strong position with DoD (all of the USN and USMC) and a good portion of the Army with the H-60.

I suppose that Sikorsky would stand on its own for a while, but cannot imagine its investors turning away from a buy out. If Sikorsky does not get sold outright, I think it will get ripped apart in the name of profit.
I can see a spinoff and standalone for a while. The main reason is that if UTC sells it outright, the US gov't is going to go after them with a big tax bill. However, if it becomes and independent company, UTC can divest itself and not have to worry about taxes. Then, if someone later buys it, there's no tax to be paid because UTC didn't get cash (although a sale would give them a nice one-time infusion they could spend on their core business). Bell/Textron is probably too financially weak to be able to afford Sikorsky.
 

VTOLicious

CLEARANCE: Top Secret
Joined
Nov 24, 2008
Messages
501
Reaction score
49
Sorry for interrupting your discussion gentlemen...

When looking at the pictures from the video I was wondering why the designers chose to install the engines/gearbox on top of the cabin fuselage.
Especially because the whole cabin is well in front of the gearbox!
And respectively, for what is the huge volume aft of the cabin used for? Fuel only? It seems the frontal area and overall height (of the SB-1) could be reduced significantly.

I have attached a sketch to illustrate my point.
Am I missing something?

BR Michael
 

Attachments

F-14D

I really did change my personal text
Senior Member
Joined
Oct 4, 2007
Messages
1,734
Reaction score
20
TomS said:
F-14D said:
I note that the video is titled "Introducing the Boeing-Sikorsky SB-1 Defiant". Does this mean the designator will change to "BS"?

IT'S A JOKE!!

What happens to the Defiant if UTC spins off Sikorsky?. Sikorsky's military side looks like a natural pickup for Boeing, so it would then be the B-1. Oh wait... Boeing already has one of those.

Seriously, though, what would happen? The current DoJ would never allow that, merger or buy. Does Sikorsky standing on it own have the resources to complete their share of this program and the potential FVL follow-on?
Well, remember that SB-1 (or SB>1) is only the Bell-Sikorsky internal designation and has nothing to do with any eventual military designation. Which name comes first seems to depend on who wrote the rpess release.

In terms of a potential sale, I don't think we should be thinking of Sikorsky as separate military and civilian "sides." Anyone who bought the company would get both. The production of civil and military product happens in the same factory and there is considerable overlap in both production and engineering staff. A buyer might abandon future civil sales efforts, but why do that when the S-92 is mainly of interest for the offshore oil rig support market?

My hunch is that it's going to be a stand-alone company, at least for a while. No one will want to buy them until the JMR/FLV program is a little firmer than it is now.
Again, I was making a joke about the Boeing-Sikorsky ;) designation.

It's unlikely that Boeing would have much interest in the civil side, they'd probably only want to go forth with just the military programs. There's precedent for this. When Boeing bought McDonnell Douglas Helicopters, they only wanted the military programs, the civil craft would have died had Lynn Tilton not stepped in and continued the civil side as MD helicopters.

Sikorsky's overall sales are down 7% for the first quarter of 2015, but civil sales are down 26%. that's probably related to the effect of lower oil prices. Sikorsky is currently the second largest helicopter prime in the world by revenue and market share (behind Boeing)., but that's due to the military side. Not as big a player on civil.

I do think that if UTC spins them off, they'll be a standalone for a while. The danger of operating as a standalone is that when you're part of a larger entity you're somewhat cushioned from the very cyclical nature of the rotorcraft market. There's also the question regarding whether the industry can really afford five primes.
 

F-14D

I really did change my personal text
Senior Member
Joined
Oct 4, 2007
Messages
1,734
Reaction score
20
VTOLicious said:
Sorry for interrupting your discussion gentlemen...

When looking at the pictures from the video I was wondering why the designers chose to install the engines/gearbox on top of the cabin.
Especially because the whole cabin is well in front of the gearbox!
And respectively, for what is the huge volume aft of the cabin used for? Fuel only? It seems the frontal area and overall height could be reduced significantly.

I have attached a sketch to illustrate my point.
Am I missing something?

BR Michael
This was actually looked at a while back in one of the other topics. The best guess is that as more became known producing X2 technology vehicles, it became apparent the mast and transmission required are so large that they have to impinge into the part of the fuselage that would normally be available for cabin space. As a result, the cabin has to be forward of the mast. In artist's depictions since around 2010, all illustrations of X2 vehicles show the whole cabin forward of the mast, while before that they didn't. This would impose an upper limit on how large an practical X2 vehicle could be. You probably won't see an x2 FVL-Heavy.
 

VTOLicious

CLEARANCE: Top Secret
Joined
Nov 24, 2008
Messages
501
Reaction score
49
the mast and transmission required are so large that they have to impinge into the part of the fuselage that would normally be available for cabin space. As a result, the cabin has to be forward of the mast.
F-14D, I'm aware of that. Did you read my post and look at the pic?

EDIT: I noticed that I wrote cabin, meaning fuselage:
"When looking at the pictures from the video I was wondering why the designers chose to install the engines/gearbox on top of the cabin fuselage."

The S-97s layout is different!
 

F-14D

I really did change my personal text
Senior Member
Joined
Oct 4, 2007
Messages
1,734
Reaction score
20
VTOLicious said:
the mast and transmission required are so large that they have to impinge into the part of the fuselage that would normally be available for cabin space. As a result, the cabin has to be forward of the mast.
F-14D, I'm aware of that. Did you read my post and look at the pic?

EDIT: I noticed that I wrote cabin, meaning fuselage:
"When looking at the pictures from the video I was wondering why the designers chose to install the engines/gearbox on top of the cabin fuselage."

The S-97s layout is different!
Yes I read your post and looked at the pic (that's why I quoted you). Using "cabin" instead of "fuselage" does have some impact. I would imagine the answer might lie in the size of the engines and part of the transmission. You'll note that even in conventional helos, once you get much above the light size, the engines tend to be on top and/or external. That also makes them easier to get to for service

The S-97 is smaller than the S-97, so that it's different is not too surprising.

BTW, you also said, "And respectively, for what is the huge volume aft of the cabin used for?" I was answering that as well.
 

bobbymike

CLEARANCE: Above Top Secret
Joined
Apr 21, 2009
Messages
9,054
Reaction score
211
http://www.janes.com/article/54127/boeing-sikorsky-defiant-next-gen-helicopter-approaches-design-review?utm_campaign=%5bPMP%5d_PC5308_J360%2011.09.15%20_KV_Deployment&utm_medium=email&utm_source=Eloqua
 

jsport

I really should change my personal text
Joined
Jul 27, 2011
Messages
1,336
Reaction score
32
VTOLicious said:
I think we're talking at cross purposes :)
so we are still no closer to an answer to your astute (IMHO) question :(
 

Triton

Donald McKelvy
Senior Member
Joined
Aug 14, 2009
Messages
9,723
Reaction score
213
Website
deeptowild.blogspot.com
"Sikorsky's Raider, Defiant Helicopter Programs Forge Ahead"
Oct 16, 2015 Graham Warwick | AviationWeek.com

Source:
http://aviationweek.com/defense/sikorskys-raider-defiant-helicopter-programs-forge-ahead

As Sikorsky looks forward to the pending merger with Lockheed Martin, two advanced rotorcraft programs are progressing at pace. The high-speed S-97 Raider has flown a second time, while the systems integration laboratory (SIL) for the SB-1 Defiant rigid coaxial-rotor compound helicopter – for the US Army Joint Multi Role (JMR) program for which Sikorsky has teamed with Boeing - will fire up this year.

The first Raider prototype completed a 1.2-hr. second flight on Sept. 29 at Sikorsky’s development test center in West Palm Beach, Florida. The aircraft, which had undergone several upgrades since its maiden flight May 22, completed several takeoffs and landings, low-speed flight and the first run-on landings, says Chris Van Buiten, vice president for Sikorsky Innovations. Final assembly of the Defiant demonstrator will begin in 2016 with the aircraft on track to fly in 2017, according to Doug Shidler, Sikorsky's JMR program director.

The first Raider prototype is not expected to fly again until the ground-based transmission system testbed (TSTB), also at West Palm Beach, has completed 200 hr. of endurance testing on the aircraft's General Electric YT706 engine, transmission, rigid coaxial rotors and tail-mounted variable-pitch propulsor. The TSTB has logged 32 hr. and plans call for 15-20 hr. of testing a week, says Dave Banquer, Raider chief engineer.

The second of the two industry-funded Raider prototypes, meanwhile, is essentially complete and will be displayed at the Association of the U.S. Army’s convention in Washington on Oct. 12-14. While aircraft 1 will be used for envelope expansion and demonstration of the Raider’s key performance parameters, aircraft 2 will be used for customer demonstrations.

The S-97 is a follow-on to Sikorsky’s X2 technology demonstrator, which exceeded 250 kt. in 2010. The Raider is designed to cruise at 220 kt. carrying weapons on external pylons, and is capable of exceeding 250 kt. when clean—100 kt. faster than any conventional helicopter, the company says.

The JMR program is demonstrating high-speed rotorcraft configurations that are candidates for the Army’s planned Future Vertical Lift (FVL) Medium program to replace the Sikorsky UH-60 Black Hawk utility and Boeing AH-64 Apache attack helicopters beginning in the mid-2030s. The 230-kt. SB-1 is also based on Sikorsky’s X2 configuration. The main task for Defiant “is to demonstrate the handing qualities of the X2 in this size class,” says Pat Donnelly, Boeing's program director.

The Defiant is now in detail design, with many parts in fabrication, Shidler says. The SIL at Sikorsky’s Stratford, Connecticut, plant will tie the aircraft’s vehicle management system hardware and software together with simulated sensors and a cockpit simulator. “It will test the digital flight control system and all it controls,” Donnelly says.

The Defiant propulsion systems testbed at West Palm Beach – similar to the TSTB for Raider - will begin running in 2016 and endurance-test a full set of dynamic components to qualify them for flight. The Defiant will be assembled in the hangar where the two Raider prototypes were built.

FVL began as a Pentagon initiative to replace all of its helicopter fleets with a family of advanced rotorcraft sharing technologies. In January, the Army introduced the concept of “Capability Sets” describing missions to be performed by the different classes of FVL. Sikorsky and Boeing are teamed to pursue FVL Medium, which encompasses Capability Sets 2, 3 and 4.

“Capability 2 is attack, a smaller platform to support the Army, Navy and Marine Corps. Capability 3 is a bigger aircraft, an assault platform carrying a squad of 12-14 troops," Donnelly says. "Capability 4 is larger still, more of a V-22 growth assault platform."

The final size of FVL Medium will depend on the customer, but “with Raider and Defiant we will bookend Capabilities 2 and 3, and collect data based on actual flight vehicles to support validation of our design tools,” says Shidler.

Interaction with potential Raider customers has increased since the aircraft began flying, according to Van Buiten. “Flying makes all the difference and we are having some exciting discussions,” he says. “The level of interest is global, but the bulk of discussions are domestic because of export authorization. We have engaged the U.S. government for permission to have more in-depth discussions with specific international customers.”

The dialog is not just with military customers, but also commercial. Raider, which is designed to carry six troops, is about the right size for a six-passenger offshore-utility and “really good,” according to Van Buiten, as a four-passenger VIP helicopter. “In VIP configuration we can do New York-Washington and New York-Boston in an hour, and Cupertino, [California] to Los Angeles in 1.5 hr. Raider is a reinvention of the helicopter. That’s the kind of thing you expect to see in Silicon Valley,” he says.

This article has been compiled and condensed from two separate pieces, which are available to subscribers. The first, "Sikorsky Raider Flies Again As Lockheed Merger Nears" goes into greater detail about the September Raider flight and plans for the program. The second, "Sikorsky-Boeing JMR Demo On Track For 2016 Assembly" looks at the JMR concept and examines rival development programs as well as the Sikorsky-Boeing bid.
 

bobbymike

CLEARANCE: Above Top Secret
Joined
Apr 21, 2009
Messages
9,054
Reaction score
211
http://breakingdefense.com/2016/10/we-defy-you-to-ride-the-sb1-simulator-with-us/
 

VTOLicious

CLEARANCE: Top Secret
Joined
Nov 24, 2008
Messages
501
Reaction score
49
bobbymike said:
http://breakingdefense.com/2016/10/we-defy-you-to-ride-the-sb1-simulator-with-us/
From the article: "...The Defiant ... is derived from Sikorsky’s award-winning X2 technology demonstrator but will be far larger – big enough to carry a dozen troops. It defeats “retreating blade stall” and other limits on normal helicopter speed by using two 25-foot-diameter coaxial rotors spinning in opposite directions and an 11-foot-diameter pusher propeller."

25ft-diameter rotors? The Raider has 34ft rotors ::) It will be rather 25ft radius!
 

yasotay

CLEARANCE: Top Secret
Senior Member
Joined
Oct 19, 2006
Messages
2,016
Reaction score
97
VTOLicious said:
bobbymike said:
http://breakingdefense.com/2016/10/we-defy-you-to-ride-the-sb1-simulator-with-us/
From the article: "...The Defiant ... is derived from Sikorsky’s award-winning X2 technology demonstrator but will be far larger – big enough to carry a dozen troops. It defeats “retreating blade stall” and other limits on normal helicopter speed by using two 25-foot-diameter coaxial rotors spinning in opposite directions and an 11-foot-diameter pusher propeller."

25ft-diameter rotors? The Raider has 34ft rotors ::) It will be rather 25ft radius!
Well... maybe they spin a lot faster... ;D
 

VTOLicious

CLEARANCE: Top Secret
Joined
Nov 24, 2008
Messages
501
Reaction score
49
VTOLicious said:
Sorry for interrupting your discussion gentlemen...

When looking at the pictures from the video I was wondering why the designers chose to install the engines/gearbox on top of the cabin fuselage.
Especially because the whole cabin is well in front of the gearbox!
And respectively, for what is the huge volume aft of the cabin used for? Fuel only? It seems the frontal area and overall height (of the SB-1) could be reduced significantly.

I have attached a sketch to illustrate my point.
Am I missing something?

BR Michael
Still don't see how the HUGE volume aft of the cabin is efficiently used ::)
Assuming the actual gearbox/fuel-volume is as depicted:
 

Attachments

TomS

CLEARANCE: Top Secret
Senior Member
Joined
Apr 16, 2008
Messages
3,264
Reaction score
149
VTOLicious said:
VTOLicious said:
Sorry for interrupting your discussion gentlemen...

When looking at the pictures from the video I was wondering why the designers chose to install the engines/gearbox on top of the cabin fuselage.
Especially because the whole cabin is well in front of the gearbox!
And respectively, for what is the huge volume aft of the cabin used for? Fuel only? It seems the frontal area and overall height (of the SB-1) could be reduced significantly.

I have attached a sketch to illustrate my point.
Am I missing something?

BR Michael
Still don't see how the HUGE volume aft of the cabin is efficiently used ::)
Assuming the actual gearbox/fuel-volume is as depicted:
Might be largely empty space. The rotors have to sit where they are for balance reasons (they have to be above CG, roughly) and the pusher needs to be well aft, clear of the top rotors. In theory, the space in between could just be filled with the bare rotor shaft, but the aerodynamics and structural implications of that are awful, so they fair it over to give smooth lines. You can't fill it up completely, because that would move CG too far aft.
 

yasotay

CLEARANCE: Top Secret
Senior Member
Joined
Oct 19, 2006
Messages
2,016
Reaction score
97
1. Fuel - requirement is to go roughly twice as far as the helicopter it is replacing. Going faster could mean a higher fuel burn rate as well.

2. Vibration Dampeners - original XH-59 had a pretty significant vibration challenge at higher speeds.

3. Electronics - requirement has a pretty impressive electronic capability.
 

TomS

CLEARANCE: Top Secret
Senior Member
Joined
Apr 16, 2008
Messages
3,264
Reaction score
149
yasotay said:
1. Fuel - requirement is to go roughly twice as far as the helicopter it is replacing. Going faster could mean a higher fuel burn rate as well.
Definitely will need a lot more gas. For comparison, the Black Hawk uses T700-701D turboshafts, rated around 1716 SHP continuous with an SFC of 0.462 lbs/SHP-hr (at sea level standard conditions), so around 790 lb/hr fuel consumption at max continuous power. The SB-1 is running a pair of T55s. They're slightly modified but in the same class as the ones currently on the CH-47, so roughly 4116 SHP and SFC of 0.51 lb/SHP-hr, for a consumption of around 2100 lbs at max continuous power. That's 2.65 times the fuel burn. Obviously, that's not the whole story -- the SB-1 may be able to operate at much less than its max continuous power for most of its flight regime, etc. But it sure tells a story about fuel use for FLV in general -- it's going to be huge compared to the current generation of aircraft.
 

Blitzo

CLEARANCE: Secret
Joined
Jun 9, 2011
Messages
362
Reaction score
0
TomS said:
yasotay said:
1. Fuel - requirement is to go roughly twice as far as the helicopter it is replacing. Going faster could mean a higher fuel burn rate as well.
Definitely will need a lot more gas. For comparison, the Black Hawk uses T700-701D turboshafts, rated around 1716 SHP continuous with an SFC of 0.462 lbs/SHP-hr (at sea level standard conditions), so around 790 lb/hr fuel consumption at max continuous power. The SB-1 is running a pair of T55s. They're slightly modified but in the same class as the ones currently on the CH-47, so roughly 4116 SHP and SFC of 0.51 lb/SHP-hr, for a consumption of around 2100 lbs at max continuous power. That's 2.65 times the fuel burn. Obviously, that's not the whole story -- the SB-1 may be able to operate at much less than its max continuous power for most of its flight regime, etc. But it sure tells a story about fuel use for FLV in general -- it's going to be huge compared to the current generation of aircraft.
A question about SB-1s powerplant -- it's meant to use T55, but is it two or just one?
I've read that SB-1 is meant to have a MTOW of 13.6 tons, and two T55s seems like a bit much for something only weighing that much?? (Ch-47 of course use two T55s and they have a MTOW of over 20 tons, whereas V-22 has MTOW of 27 tons using two T406s).

Many of the CGIs seem to show SB1 with two inlets and outlet suggestive of two turboshafts, and the promo video seems to show two turboshafts internally, but two T55s seems excessive? Is it possible that it's just one T55 instead for the SB1 demonstrator, similar to how a single yt706 is powers the 5 ton S-97 demonstrator as well?

Or, are there any indications that definitively indicates how many turboshafts will power the SB1 demonstrator?
 

VTOLicious

CLEARANCE: Top Secret
Joined
Nov 24, 2008
Messages
501
Reaction score
49
Blitzo said:
TomS said:
yasotay said:
1. Fuel - requirement is to go roughly twice as far as the helicopter it is replacing. Going faster could mean a higher fuel burn rate as well.
Definitely will need a lot more gas. For comparison, the Black Hawk uses T700-701D turboshafts, rated around 1716 SHP continuous with an SFC of 0.462 lbs/SHP-hr (at sea level standard conditions), so around 790 lb/hr fuel consumption at max continuous power. The SB-1 is running a pair of T55s. They're slightly modified but in the same class as the ones currently on the CH-47, so roughly 4116 SHP and SFC of 0.51 lb/SHP-hr, for a consumption of around 2100 lbs at max continuous power. That's 2.65 times the fuel burn. Obviously, that's not the whole story -- the SB-1 may be able to operate at much less than its max continuous power for most of its flight regime, etc. But it sure tells a story about fuel use for FLV in general -- it's going to be huge compared to the current generation of aircraft.
A question about SB-1s powerplant -- it's meant to use T55, but is it two or just one?
I've read that SB-1 is meant to have a MTOW of 13.6 tons, and two T55s seems like a bit much for something only weighing that much?? (Ch-47 of course use two T55s and they have a MTOW of over 20 tons, whereas V-22 has MTOW of 27 tons using two T406s).

Many of the CGIs seem to show SB1 with two inlets and outlet suggestive of two turboshafts, and the promo video seems to show two turboshafts internally, but two T55s seems excessive? Is it possible that it's just one T55 instead for the SB1 demonstrator, similar to how a single yt706 is powers the 5 ton S-97 demonstrator as well?

Or, are there any indications that definitively indicates how many turboshafts will power the SB1 demonstrator?
Given the envisaged speed and hot/high performance it is plausible that it requires two engines with lots of excess power.

For comparison:

UH-60L Blackhawk:
Powerplant: 2 × General Electric T700-GE-701C turboshaft, 1,890 shp (1,410 kW) each
Max. takeoff weight: 23,500 lb (10,660 kg)
Cruise Speed: 150 kt

->3.78kg/kW

CH-47F Chinook:
Powerplant: 2 × Lycoming T55-GA-714A turboshaft, 4,733 shp (3,529 kW) each
Max. takeoff weight: 50,000 lb (22,680 kg)
Cruise Speed: 160 kt

->3.21kg/kW

SB-1 Defiant:
Powerplant: 2 × Lycoming T55-GA-714A turboshaft, 4,733 shp (3,529 kW) each
Max takeoff weight: 29,980 lb (13,600kg)
Cruise Speed: 250kt

->1.93kg/kW

S-97 Raider:
Powerplant: 1 × General Electric YT706 , 2,600 shp (1,900 kW)
Max takeoff weight: 11,000 lb (4,990 kg)
Cruise Speed: 240kt

->2.63kg/kW
 

TomS

CLEARANCE: Top Secret
Senior Member
Joined
Apr 16, 2008
Messages
3,264
Reaction score
149
Blitzo said:
A question about SB-1s powerplant -- it's meant to use T55, but is it two or just one?
I've read that SB-1 is meant to have a MTOW of 13.6 tons, and two T55s seems like a bit much for something only weighing that much?? (Ch-47 of course use two T55s and they have a MTOW of over 20 tons, whereas V-22 has MTOW of 27 tons using two T406s).

Many of the CGIs seem to show SB1 with two inlets and outlet suggestive of two turboshafts, and the promo video seems to show two turboshafts internally, but two T55s seems excessive? Is it possible that it's just one T55 instead for the SB1 demonstrator, similar to how a single yt706 is powers the 5 ton S-97 demonstrator as well?

Or, are there any indications that definitively indicates how many turboshafts will power the SB1 demonstrator?
Yes, it's definitely two engines.

http://aviationweek.com/awin-only/bell-sikorskyboeing-build-army-jmr-rotorcraft-demonstrators

With rigid coaxial rotors, pusher propeller and advanced fly-by-wire controls, "Defiant will use Sikorsky’s proven X2 technology to overcome aircraft design challenges," says Mick Maurer, Sikorsky’s president. The demonstrator will be powered by a pair of Honeywell T55 turboshafts.
 

yasotay

CLEARANCE: Top Secret
Senior Member
Joined
Oct 19, 2006
Messages
2,016
Reaction score
97
Both JMR aircraft SB>1 and V-280 are using currently available engines for their test program. The engine they want to have has just started development. So while both will have an overabundance of power, they will not demonstrate the range expected of an FVL (recall they are technology demonstrators) program.

In related news... SB>1 finally breaks cover.
 

Attachments

Blitzo

CLEARANCE: Secret
Joined
Jun 9, 2011
Messages
362
Reaction score
0
TomS said:
Blitzo said:
A question about SB-1s powerplant -- it's meant to use T55, but is it two or just one?
I've read that SB-1 is meant to have a MTOW of 13.6 tons, and two T55s seems like a bit much for something only weighing that much?? (Ch-47 of course use two T55s and they have a MTOW of over 20 tons, whereas V-22 has MTOW of 27 tons using two T406s).

Many of the CGIs seem to show SB1 with two inlets and outlet suggestive of two turboshafts, and the promo video seems to show two turboshafts internally, but two T55s seems excessive? Is it possible that it's just one T55 instead for the SB1 demonstrator, similar to how a single yt706 is powers the 5 ton S-97 demonstrator as well?

Or, are there any indications that definitively indicates how many turboshafts will power the SB1 demonstrator?
Yes, it's definitely two engines.

http://aviationweek.com/awin-only/bell-sikorskyboeing-build-army-jmr-rotorcraft-demonstrators

With rigid coaxial rotors, pusher propeller and advanced fly-by-wire controls, "Defiant will use Sikorsky’s proven X2 technology to overcome aircraft design challenges," says Mick Maurer, Sikorsky’s president. The demonstrator will be powered by a pair of Honeywell T55 turboshafts.
ah okay, cool thanks for the confirmation.

Kind of surprising, that they're using such powerful turboshafts for a substantially lighter aircraft. I wonder if the coaxial/pusher prop configuration requires a much more powerful set of engines despite its smaller size...


VTOLicious said:
Given the envisaged speed and hot/high performance it is plausible that it requires two engines with lots of excess power.

For comparison:

UH-60L Blackhawk:
Powerplant: 2 × General Electric T700-GE-701C turboshaft, 1,890 shp (1,410 kW) each
Max. takeoff weight: 23,500 lb (10,660 kg)
Cruise Speed: 150 kt

->3.78kg/kW

CH-47F Chinook:
Powerplant: 2 × Lycoming T55-GA-714A turboshaft, 4,733 shp (3,529 kW) each
Max. takeoff weight: 50,000 lb (22,680 kg)
Cruise Speed: 160 kt

->3.21kg/kW

SB-1 Defiant:
Powerplant: 2 × Lycoming T55-GA-714A turboshaft, 4,733 shp (3,529 kW) each
Max takeoff weight: 29,980 lb (13,600kg)
Cruise Speed: 250kt

->1.93kg/kW

S-97 Raider:
Powerplant: 1 × General Electric YT706 , 2,600 shp (1,900 kW)
Max takeoff weight: 11,000 lb (4,990 kg)
Cruise Speed: 240kt

->2.63kg/kW
Thanks, yeah I think that makes sense (wrt above)
 

yasotay

CLEARANCE: Top Secret
Senior Member
Joined
Oct 19, 2006
Messages
2,016
Reaction score
97
Kind of surprising, that they're using such powerful turboshafts for a substantially lighter aircraft. I wonder if the coaxial/pusher prop configuration requires a much more powerful set of engines despite its smaller size...
Not an aerospace engineer but I recall that drag is *exponentially* increased with speed, or some such wizardry. Damned physics, always getting in the way of coolness.
 

Sundog

CLEARANCE: Top Secret
Senior Member
Joined
Aug 2, 2006
Messages
2,631
Reaction score
42
yasotay said:
Kind of surprising, that they're using such powerful turboshafts for a substantially lighter aircraft. I wonder if the coaxial/pusher prop configuration requires a much more powerful set of engines despite its smaller size...
Not an aerospace engineer but I recall that drag is *exponentially* increased with speed, or some such wizardry. Damned physics, always getting in the way of coolness.
Dynamic pressure goes up with the square of velocity (pressure or form drag), however, there are various forms of drag. Total drag versus airspeed actually looks basically like a stretched out "U" versus airspeed. You usually want your cruise point to occur at the lowest point, in the drag bucket ( sometimes there's a little divet there, that I won't go into here) since that is where minimum drag occurs and if the engine was designed for the aircraft that should be where it is most efficient. However, for helicopters it is bit more complex due to the rotor down wash. Now there are some fun calculations I haven't performed since my V/STOL aerodynamics course.

I'm definitely looking forward to seeing both competitors fly, but I really like how the SB-1 is shaping up.
 
Top