Go Back  PPRuNe Forums > Aircrew Forums > Rotorheads
Reload this Page >

Helicopters and Fly-by-wire?

Rotorheads A haven for helicopter professionals to discuss the things that affect them

Helicopters and Fly-by-wire?

Old 4th Jun 2011, 11:49
  #1 (permalink)  
Thread Starter
 
Join Date: Jan 2006
Location: here, there, everywhere
Posts: 280
Question Helicopters and Fly-by-wire?

Are there any helicopters using a fly-by-wire system? I'm not thinking SAS/ASE, but a fully blown FBW, like for instance in A-320, or F-16, where pilot's inputs feed the flight control computers, which in turn execute control movements to meet the pilot's demands (like roll/pitch rate, load factor etc.) and there's no mechanical reversion. I am asking, because I think that helicopters, with all the control complexity, cross-coupling, instabilities and generally less-than-perfect handling qualities (at least compared to FW a/c) seem to be perfect candidates for such a system, which could greatly simplify the handling, ease pilot's workload and enhance safety...

So, are such systems currently available, or under developement, or maybe there are some issues precluding the use of FBW in helicopters?
Stuck_in_an_ATR is offline  
Old 4th Jun 2011, 11:57
  #2 (permalink)  
 
Join Date: Dec 2006
Location: australia
Posts: 202
yeh I am pretty sure the NH90 (MRH in Oz) is a full FBW aircraft...triple redundancy or something as well?? Not sure about any other types out there though.
Turkeyslapper is offline  
Old 4th Jun 2011, 12:31
  #3 (permalink)  
 
Join Date: May 2005
Location: WA
Posts: 27
The EC145 is more or less FBW. If hydraulics fail there is no mechanical reversion. For that matter so is the 412 except the wires are a bit thicker. Either way you are still buggered with total hyd failure.
Not quite what you were asking I know!
My point is, we have already taken the scariest step and few of us really noticed.
FBW . Beg deal !! It’s an autopilot.
Gymble is offline  
Old 4th Jun 2011, 12:35
  #4 (permalink)  
 
Join Date: Feb 2006
Location: On the big blue planet
Posts: 941
I think, the NH-90 is so far the only one which comes with full FBW as standard.
The Comanche had FBW and also some other prototypes. For instance, the DLR in Germany is flying an EC 135 testbed with full "fly by light" system.

skadi
skadi is offline  
Old 4th Jun 2011, 12:40
  #5 (permalink)  
 
Join Date: Feb 2006
Location: On the big blue planet
Posts: 941
The EC145 is more or less FBW. If hydraulics fail there is no mechanical reversion.


skadi
skadi is offline  
Old 4th Jun 2011, 12:41
  #6 (permalink)  
TRC
 
Join Date: Aug 2006
Location: Wiltshire, UK
Posts: 506
... an EC 135 testbed with full "fly by light" system
That's all very well, but what happens at night or on a really cloudy day?
TRC is offline  
Old 4th Jun 2011, 12:45
  #7 (permalink)  
 
Join Date: Feb 2006
Location: On the big blue planet
Posts: 941
That's all very well, but what happens at night or on a really cloudy day?
Serious question? It will fly as usual!

Fly-by-light EC135 helicopter makes first flight-05/02/2002-Flight International


skadi
skadi is offline  
Old 4th Jun 2011, 12:47
  #8 (permalink)  
 
Join Date: Sep 2010
Location: ...in sight of palmtrees
Age: 39
Posts: 97
The NH-90 is full FBW..not much "monkey skills" or particulary good basic Airwork needed since the sistem "cleans and correct" all the "wrong" inputs....whats left to the pilot is to manage all the systems...which can be challenging as well.....but werent we supposed to be pilots???...Cheers
212_Nightdipper is offline  
Old 4th Jun 2011, 19:02
  #9 (permalink)  
 
Join Date: Sep 2000
Location: UK
Age: 44
Posts: 1,589
I also read the Canadians have a FBW 205 or somesuch doing similar stuff like the DLR 135.
Brilliant Stuff is offline  
Old 4th Jun 2011, 22:12
  #10 (permalink)  
 
Join Date: Aug 2007
Location: In England
Posts: 373
Stuck in an ATR....Yep..the NH90 is the only fielded full FBW helo as yet ...and don't forget aspects of V22. You are right in assuming FBW would bring the same and some additional benefits to rotorcraft (depending on size and role) and that the challenge has been more complex and expensive in sorting it. Do not forget that FW FBW took many years of experiment, research and data gathering on specially rebuilt test platforms such as the EAP and a Jaguar at Farnborough..as just in the UK example. Several countries had experimental programmes running from the 80s onwards to sort the development...with only the US and Franco German programmes seeing their results reaching conclusions. The UK spent many years gathering the immense handling qualities data required to understand the control dynamic issues that would lead to the programming of any helo FBW AFCS. This also contributed jointly to the equivalent NASA programme which fed the Commanche AFCS development and design. In the UK we were to have a Lynx FBW development programme but despite it being a high priority research programme it was
cancelled in 1990.....it would have proven of immense value to the EH101 in due course, as well as aircraft such as the new Wildcat...but there we go...the UK committed techno industrial suicide again! Also at one stage there might have been some FBW in the Merlin HMA2 upgrade happening now...but the risks were considered to high for the time and money available so it has been dropped. Any other questions..PM me.

Last edited by Tallsar; 4th Jun 2011 at 22:22.
Tallsar is offline  
Old 5th Jun 2011, 01:09
  #11 (permalink)  
 
Join Date: Mar 2005
Location: Poplar Grove, IL, USA
Posts: 851
Originally Posted by Um... lifting...
The CH-148 variant of the S-92 is also fbw.
Yup. Also Sikorsky has a couple FBW UH60's and the X2. They had the Comanche. The CH53K will also be FBW.

-- IFMU
IFMU is offline  
Old 5th Jun 2011, 02:01
  #12 (permalink)  
 
Join Date: Oct 2002
Location: 1 Dunghill Mansions, Putney
Posts: 1,797
Originally Posted by IFMU
Sikorsky has a couple FBW UH60's and the X2. They had the Comanche. The CH53K will also be FBW
The irony here, given Tallsar's post, being that Sikorsky's FBW is a UK system (BAE).

The BA609, like the V-22, is FBW. Kawasaki's BK117 P5 and NASA's JUH-60 RASCAL demonstrators were also FBW.

The AH-64A and Apache AH Mk1 (but not AH-64D) also have a single-channel FBW system as the Back-Up Control System (BUCS).

I/C
Ian Corrigible is offline  
Old 5th Jun 2011, 02:45
  #13 (permalink)  
 
Join Date: Feb 2005
Location: KPHL
Posts: 340
I also read the Canadians have a FBW 205 or somesuch doing similar stuff like the DLR 135.
The NRC (National Research Council) runs a 205 and a 412 with one pilot FBW, and the other monitoring mechanical flight controls. The aircraft are used for research and development of FBW control laws, amongst many other things.

The CH148 (S92) is fully FBW, but is still under development. Many successful flight hours so far, but the number of minute aspects that must be managed in developing a full FBW control law is quite overwhelming.


I agree with Stuck-in-ATR's original post, that helicopters are ideal candidates for FBW. There is tremendous potential for vast improvements in stability & control, and reductions in workload. However, there are two issues that make it difficult: one is that the nature of the operation makes the control laws much more complicated, the other is that most helicopters are not economically feasible when the base model gets loaded with expensive avionics or the program suffers huge developmental costs.

Cheers,
Matthew.
Matthew Parsons is offline  
Old 5th Jun 2011, 12:30
  #14 (permalink)  
 
Join Date: Aug 2007
Location: In England
Posts: 373
....ATR....I think you can conclude that overall, helo FBW has been underdeveloped and therefore under-utilised. As MP's post implies...it is very risky and costly to try and design a platform and do all the FBW development on that platform as part of a production programme. V22 and I fear S92 suffers from this approach, Although 609 has gained much from the struggles to get V22 to work. NH90 has had problems but they were in part alleviated by the earlier research work done. Comanche is the irony as it had utilised all the tailored handling qualities research and data gathering done by both NASA and the UK RAE...only to be cancelled! Certainly it is not a sensible approach to assume that a rotorcraft designed with conventional controls and AFCS can quite easily be retrofitted with full FBW...unless you have variable time and an infinite budget of course!
Tallsar is offline  
Old 5th Jun 2011, 13:17
  #15 (permalink)  
 
Join Date: Jan 2006
Location: Western MA
Posts: 455
I believe the US Army has paid for some H60 FBW feasibility studies for their fleet.
Dan Reno is offline  
Old 5th Jun 2011, 17:08
  #16 (permalink)  
 
Join Date: Nov 2003
Location: U.K.
Posts: 1,066
Yes, I remember reading about it for the uh-60m, a quick google search showed this:
US Army revives interest in fly-by-wire for Black Hawks
By Stephen Trimble


A fly-by-wire upgrade for the Sikorsky UH-60M Black Hawk is back under serious consideration by the US Army.
Army acquisition officials "have a plan" to reinsert funding for fly-by-wire technology, which was removed from the UH-60M programme after 2008, says Maj Gen R Mark Brown, deputy for acquisition and systems management in the office of the assistant secretary of the army for acquisition, technology and logistics.
Brown's remarks come as Sikorsky nears the end of a two-year, 400h flight demonstration programme for the fly-by-wire upgrade, and show a revival of interest in the technology. Fielding an aircraft without mechanical linkages should have arrived with the Sikorsky/Boeing RAH-66 Comanche, but the aircraft was cancelled in 2004.

© US Army

Fly-by-wire was also inserted into the UH-60M upgrade, but the army declined to move the technology into production two years ago.
"We thought it was more important to buy less-capable aircraft faster and relieve our force structure," says Brown.
Inserting fly-by-wire into the UH-60M will save about 220kg (484lb), says Col Neil Thurgood, programme manager for utility helicopters. The technology also enables the army's vision to convert at least some of its Black Hawks into optionally piloted vehicles by the end of the decade.
The key benefit of fly-by-wire, however, is improved handling, says Thurgood. Pilots would no longer have to worry about controlling the aircraft in the last 650ft (200m) of a flight, when their eyes should be scanning the area outside the cockpit, he says.
Regards
Aser
Aser is offline  
Old 5th Jun 2011, 19:52
  #17 (permalink)  
 
Join Date: Mar 2008
Location: Where I'm pointing...
Posts: 583
In talking about FBW, are control inputs and linkages, including force feedback to the controls separable from the system that decides/overrides pilot inputs?

I.e. In creating an electronic control system, is it required to have this aided by a computer, or is that just the next logical progression/justifying factor?
birrddog is offline  
Old 7th Jun 2011, 03:33
  #18 (permalink)  
 
Join Date: Feb 2005
Location: KPHL
Posts: 340
birddog,

Theoretically, any control system you can imagine is possible. However, once you get into certifying the FBW system you will find some restriction. Imagine looking at a helicopter cockpit and you see one joystick, nothing else for 4-axis flight control.

In my opinion, this will be a challenge in the future. We can build something that is easy to fly and seems intuitive, but may not meet certification criteria. Not an insurmountable obstacle, but another challenge (=expense) that may delay commercial FBW.

Cheers,
Matthew.
Matthew Parsons is offline  
Old 7th Jun 2011, 10:45
  #19 (permalink)  

Purveyor of Egg Liqueur to Lucifer
 
Join Date: Nov 2002
Location: Alles über die platz
Posts: 4,617
For instance, the DLR in Germany is flying an EC 135 testbed with full "fly by light" system.
Is that not just a fancy way of saying 'solar powered' ?

I guess if it was the blades that had the solar panels on them, in flight the whole area of the disc becomes a large receptor which becomes vastly larger than the 4/5 individual blades themselves.
As shown in the pic below, instead of just the surface area of the 4 blades themselves producing the electricity, you'd have a panel the size of the red area as shown here;



or you could have a rotor system something like this to accomodate the solar panels;




But I guess the size and number of the batteries required would be the limiting factor for practical use, hence it's only on a testbed....for now.



But where do you stop?
Thermal power units that take the heat from the leading edges or maybe even little wind turbines along the leading edges topping up the batteries, the possibilities are endless... !
SilsoeSid is offline  
Old 7th Jun 2011, 12:35
  #20 (permalink)  
 
Join Date: Aug 2009
Location: Texas
Age: 61
Posts: 5,562
A few bits and pieces ...

1. Comanche was not only FBW, it didn't have rudder pedals.

2. Sikorsky UH-60 Blackhawk has had a fly-by-wire flight control surface, the horizontal stab, since the A model. (You can revert it to manual control, but in auto mode it exhibits all of the characteristics of a fly-by-wire control surface. It moves to help you without you doing anything.)

At certain airspeeds, this can lead to a bit of "hunting" (depending upon what you are doing), but one place that the automatic programming of the horizontal stab shines is during autorotation.
Lonewolf_50 is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information

Copyright © 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.