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

JMR (Joint Multi-Role) & FVL (Future Vertical Lift) Programs

DWG

ACCESS: Top Secret
Joined
Feb 11, 2007
Messages
980
Reaction score
870
She's a tall girl... I guess that what they are all thinking.
Here's a shot of the V-280 with some folks. I post it for height comparison. The bigger thing to me is not so much how tall the two are fully ready for flight, but how big they are when folded up.
Without disagreeing in the slightest with the point on folded/hangar size, there's also the issue of maintaining them on austere forward operating locations and how you manage to do any needed work on the SB>1's rotors/rotor hub - stepladder on top of a HMMWV?
 

F-14D

I really did change my personal text
Senior Member
Joined
Oct 4, 2007
Messages
1,810
Reaction score
270
She's a tall girl... I guess that what they are all thinking.
Here's a shot of the V-280 with some folks. I post it for height comparison. The bigger thing to me is not so much how tall the two are fully ready for flight, but how big they are when folded up.
Without disagreeing in the slightest with the point on folded/hangar size, there's also the issue of maintaining them on austere forward operating locations and how you manage to do any needed work on the SB>1's rotors/rotor hub - stepladder on top of a HMMWV?

That's an incredibly excellent point
 

F-14D

I really did change my personal text
Senior Member
Joined
Oct 4, 2007
Messages
1,810
Reaction score
270

Grey Havoc

The path not taken.
Senior Member
Joined
Oct 9, 2009
Messages
15,026
Reaction score
4,761
Without disagreeing in the slightest with the point on folded/hangar size, there's also the issue of maintaining them on austere forward operating locations and how you manage to do any needed work on the SB>1's rotors/rotor hub - stepladder on top of a HMMWV?
Some sort of maintenance robot, autonomous or otherwise? (Send for the Droids!)
 

DWG

ACCESS: Top Secret
Joined
Feb 11, 2007
Messages
980
Reaction score
870
Without disagreeing in the slightest with the point on folded/hangar size, there's also the issue of maintaining them on austere forward operating locations and how you manage to do any needed work on the SB>1's rotors/rotor hub - stepladder on top of a HMMWV?
I was thinking some more about this, and even with flip-out working platforms at fuselage top height, which ISTR UH-60 has for the forward maintenance scenario, that top rotor hub is still going to be at head height. If Sikorsky/Boeing haven't addressed forward maintenance adequately I can see it coming back to bite them in the assessment.
 

yasotay

ACCESS: Top Secret
Top Contributor
Senior Member
Joined
Oct 19, 2006
Messages
2,645
Reaction score
1,067
Without disagreeing in the slightest with the point on folded/hangar size, there's also the issue of maintaining them on austere forward operating locations and how you manage to do any needed work on the SB>1's rotors/rotor hub - stepladder on top of a HMMWV?
I was thinking some more about this, and even with flip-out working platforms at fuselage top height, which ISTR UH-60 has for the forward maintenance scenario, that top rotor hub is still going to be at head height. If Sikorsky/Boeing haven't addressed forward maintenance adequately I can see it coming back to bite them in the assessment.
Ever pulled a ~15 foot tall, very heavy, transmission in a field environment? 16 rotor blades per aircraft to inspect (which is why Bell pointed out in the article they have six) on a regular basis.
 

VTOLicious

ACCESS: Top Secret
Senior Member
Joined
Nov 24, 2008
Messages
743
Reaction score
378
She's a tall girl... I guess that what they are all thinking.
Here's a shot of the V-280 with some folks. I post it for height comparison. The bigger thing to me is not so much how tall the two are fully ready for flight, but how big they are when folded up.
Without disagreeing in the slightest with the point on folded/hangar size, there's also the issue of maintaining them on austere forward operating locations and how you manage to do any needed work on the SB>1's rotors/rotor hub - stepladder on top of a HMMWV?
:D
 

Attachments

  • IMG_20190325_085635.jpg
    IMG_20190325_085635.jpg
    656.4 KB · Views: 46

F-14D

I really did change my personal text
Senior Member
Joined
Oct 4, 2007
Messages
1,810
Reaction score
270
In the upcoming FLRAA RFP, it will be interesting to see how the final requirements for two key factors play out, speed and range.

In the former case, if the requirement for speed is significantly lowered (not saying it will be), that could mean one of two things. First, as seems to be happening on some contracts throughout DoD, competition is becoming the end, not the means. In other words, the acquisition folks want there to be a "competition" even if it means compromising mission needs. The more cynical suspicion would be that the fix is in.

The range question would be a bit more complicated. When JMR/FVL got started, I believe everyone was told they could base their ultimate designs and capabilities on the Government' FATE (Future Affordable Technology Engine) that Army was developing separately. However, Army's pace on getting FATE on line doesn't appear they're going to deliver it when FLRAA is going to need it. Bell has already said they're going to go with a Rolls Royce engine for their production V-280s, I don't know where Defiant-X is on this. My point is that if either aircraft has to use a heavier, thirstier engine than was expected, some performance requirements may have to be lowered.

This exact thing happened to the V-22. During design Bell-Boeing were told the Gov't would supply an advanced engine it was going to select, both Pratt and GE were competing with advanced designs. A selection was made, but at the last moment the selection group was overruled and the V-22 team was told they would be supplied with an Allison engine. It was more powerful than the other two engines, but it weighed more and burned more fuel. Bell-Boeing responded that they could work with that GFE engine after some redesign, but with it they would not be able to meet all of their original promises. So the Gov't relaxed some of the requirements, including range.
 

F-14D

I really did change my personal text
Senior Member
Joined
Oct 4, 2007
Messages
1,810
Reaction score
270
Interesting statement in the video ( :011) : "We showed that 230 knots that's what the Army asked for..." . I thought that so far the Army had set the threshold speed at 250 knots, which the SB team had said they'd meet. Am I wrong or has something changed?
 

yasotay

ACCESS: Top Secret
Top Contributor
Senior Member
Joined
Oct 19, 2006
Messages
2,645
Reaction score
1,067
Well if they flew today at 230 knots straight and level then that is new. Perhaps they are aware of the requirements.
 

F-14D

I really did change my personal text
Senior Member
Joined
Oct 4, 2007
Messages
1,810
Reaction score
270
What I was getting at was the way they phrased it, they were implying they met the Army's requirement at 230 knots. Have they seen the RFP already and the speed requirement is lower, or am I reading too much into this?

I also wonder how much power and torque they were using @ 230 knot level flight.
 

TomcatViP

Hellcat
Joined
Feb 12, 2017
Messages
3,799
Reaction score
2,885
I think the value was lowered in the initial part of the competition to get more entrants. They are also claiming a 70% power setting to reach that speed (from my memory only).
 

DWG

ACCESS: Top Secret
Joined
Feb 11, 2007
Messages
980
Reaction score
870
For "Hey, we finally cranked her up to 230!" they sure did spend a lot of that clip talking about low speed lifting capability.

And I presume the lift requirement is for more than just *low speed* capability. I don't expect them to get to 230 with a howitzer underneath, but equally I'd expect more than just walking pace.
 

_Del_

I really should change my personal text... Or not.
Joined
Jan 4, 2012
Messages
643
Reaction score
416
For "Hey, we finally cranked her up to 230!" they sure did spend a lot of that clip talking about low speed lifting capability.

And I presume the lift requirement is for more than just *low speed* capability. I don't expect them to get to 230 with a howitzer underneath, but equally I'd expect more than just walking pace.
I think they're just pointing out that their lower disc loading should give better lift capability and hot-high performance assuming both aircraft would get the same shp engines.
OEI scenarios will favour them, too (at least in the case of a sling load and hover).

The entire competition reasserts the old maxim that "what helps you in a hover is bound to hurt in drag/speed department." It's all about where the desires for compromise come in.
 

yasotay

ACCESS: Top Secret
Top Contributor
Senior Member
Joined
Oct 19, 2006
Messages
2,645
Reaction score
1,067
No one does OEI sling loads. But I do agree with the comment about compromise. Given the "pivot to the Pacific" range and endurance will likely be at the top of the list.
 

_Del_

I really should change my personal text... Or not.
Joined
Jan 4, 2012
Messages
643
Reaction score
416
No one does OEI sling loads
Well, noone plans an OEI sling load ;) You're just going to cut the load, but the lower disc loading gives you more time to recognize what's going on, flash the landing lighta, and perhaps avoid cutting it above or placing it otherwise on the little squishy men wearing green who had helped hook it earlier. They probably appreciate the few extra seconds to run the opposite direction to the rendezvous point.
 

F-14D

I really did change my personal text
Senior Member
Joined
Oct 4, 2007
Messages
1,810
Reaction score
270
For "Hey, we finally cranked her up to 230!" they sure did spend a lot of that clip talking about low speed lifting capability.

And I presume the lift requirement is for more than just *low speed* capability. I don't expect them to get to 230 with a howitzer underneath, but equally I'd expect more than just walking pace.
I think they're just pointing out that their lower disc loading should give better lift capability and hot-high performance assuming both aircraft would get the same shp engines.
OEI scenarios will favour them, too (at least in the case of a sling load and hover).

The entire competition reasserts the old maxim that "what helps you in a hover is bound to hurt in drag/speed department." It's all about where the desires for compromise come in.

Defiant-X, if they get it to work, has always been expected to have better hover performance. For one thing, no matter how much extra twist you can put on a Tilt-Rotor's blades, you can't get around the fact that there's a wing there with its attendant weight and is in the Proprotor's downwash. In fact, what Bell says they can do for the hot and high requirement is meet or somewhat exceed the Army's requirement, but not overwhelmingly so. They expect to dominate in other areas. Sikorsky-Boeing's claim for Defiant, OTOH, is a HOGE at an altitude much greater than the Army requirement. It's all a tradeoff between capabilities, assuming both meet their promises.

BTW, the V-280 has already demonstrated carrying external loads.
 

F-14D

I really did change my personal text
Senior Member
Joined
Oct 4, 2007
Messages
1,810
Reaction score
270
I think the value was lowered in the initial part of the competition to get more entrants. They are also claiming a 70% power setting to reach that speed (from my memory only).
That would be something I worry about, making competition an end rather than a means. They had four entrants, and at the time they cut it down to just Valor and Defiant, Army said they werren't going to a full and open competition because they felt that those two were the only ones who would be technically capapble of meeting the requirement.
 
Last edited:

yasotay

ACCESS: Top Secret
Top Contributor
Senior Member
Joined
Oct 19, 2006
Messages
2,645
Reaction score
1,067
Never underestimate the Army's myopia. This is the same service that at the US entrance into World War 2 told Congress that the Horse Cavalry had to be doubled in size. The Army does h-e-l-i-c-o-p-t-e-r-s. If the requirement that is written after analysis is too demanding for anything that looks like a helicopter, well ...
 

Hydroman

ACCESS: Restricted
Joined
Jan 28, 2008
Messages
17
Reaction score
34
As an example, the Comanche could have gone into service as its intended light attack/scout role but the Army messed that up by piling on all nice to have features/capabilities up front, bringing the weight way up, adversely affecting engine and vehicle performance then cancelling the program all together, they could have grown its capabilities gradually over time.
 

Similar threads

Top