Ingenuity Helo On Mars

[Brett327]

I like my helos like I like my coffee, no FBW.

To be serious, I know the tech is great and has been proven, but it's always made the hairs on my neck stand up. Probably just my ignorance of the FBW systems and redundancies, and also seeing and experiencing wiring and electrical problems on the shitter I flew (70/80's tech). Also, the environments and levels of maint support they're operated in.

I'm probably a Luddite regarding this issue. But, goddamit, I would want a mechanical link to that rotorhead.

Pointy nosed guys have been using FBW for decades. In the Rhino, it’s a redundant, four channel FCS system, and I’m not aware of an FCS failure that resulted in a catastrophic outcome. Lose an aileron or rudder? No problem. The system compensates to maintain control and do its best to give the pilot what is being asked for using the remaining flight control surfaces. Its not perfect, but the advantages are pretty overwhelming. The fact that they could create an entirely new flight regime with PLM for landing on the boat, with a software upgrade, it pretty mind blowing.

 

[Pags]

I like my helos like I like my coffee, no FBW.

To be serious, I know the tech is great and has been proven, but it's always made the hairs on my neck stand up. Probably just my ignorance of the FBW systems and redundancies, and also seeing and experiencing wiring and electrical problems on the shitter I flew (70/80's tech). Also, the environments and levels of maint support they're operated in.

I'm probably a Luddite regarding this issue. But, goddamit, I would want a mechanical link to that rotorhead.

Yeah, what Brett said. It was pretty awesome to implement totally new flight control modes and different approach capabilities with a SW drop on the V-22.

 

[JTS11]

Pointy nosed guys have been using FBW for decades. In the Rhino, it’s a redundant, four channel FCS system, and I’m not aware of an FCS failure that resulted in a catastrophic outcome. Lose an aileron or rudder? No problem. The system compensates to maintain control and do its best to give the pilot what is being asked for using the remaining flight control surfaces. Its not perfect, but the advantages are pretty overwhelming. The fact that they could create an entirely new flight regime with PLM for landing on the boat, with a software upgrade, it pretty mind blowing.

No, I get it. I was just relaying a tongue and cheek perspective from flying an old helo. If the CH-53K can land hands off in the dust at night, then I'm a believer.

I'd still like a mechanical link though ?

 

[Gatordev]

Pointy nosed guys have been using FBW for decades. In the Rhino, it’s a redundant, four channel FCS system, and I’m not aware of an FCS failure that resulted in a catastrophic outcome. Lose an aileron or rudder? No problem. The system compensates to maintain control and do its best to give the pilot what is being asked for using the remaining flight control surfaces. Its not perfect, but the advantages are pretty overwhelming. The fact that they could create an entirely new flight regime with PLM for landing on the boat, with a software upgrade, it pretty mind blowing.

Sure, all great stuff. But you have to also understand where the helo guys are coming from. The -60 has had a long-standing FBW system (but not the total system) that initially had near-catastrophic failures and programmed the community to fear it. That lessened over the (many) years, but it's still a failure that requires the PAC to utilize exclamation marks during the EP. Overkill? I'd argue yes, but it's still not an unheard of failure.

All that said, Sikorsky has had a fully FBW -60 flying for several years now (or at least it did), so I guess the overall idea has matured.

 

[Jim123]

The -60 has had a long-standing FBW system (but not the total system) that initially had near-catastrophic failures and programmed the community to fear it.

A couple of things to come out of the 60's FBW stabilator that have me puzzled about a handful of specific airplane crashes in the last few years-

With the now-infamous MCAS on the 737, all they had to do was build it using two completely redundant systems and build it to automatically shutdown both if they disagreed by more than a certain amount. I think I still remember that the tolerance on the -60 stab was if one channel disagreed with the other by 5-12° or something like that. Boeing could have averted a corporate disaster by just cribbing Sikorsky's notes from 1980 on their damn stab, which funny enough shared a broadly similar purpose- to make the aircraft "feel" a bit different.

Pitot heat 100% of the time in IMC. There are GA pilots who think of the pitot heat as something you use if you're worried about icing but don't turn it on as a matter of course in low visibility or flying through clouds. It was kind of a LAMPS-ism but if you didn't have the probe heat on in the simulator and you flew through a simulated cloud, the sim operator would crash you by commanding the stabilator to program full retard, just as the aircraft would supposedly do if the airspeed input to the stab channels went wonky... or so the community superstitions would have us believe.

 

[taxi1]

I'd still like a mechanical link though ?

Burt Rutan’s Virgin-X space plane and its high altitude ferry are both pure mechanical controls. Kind of cool.

 

[JTS11]

Pitot heat 100% of the time in IMC. There are GA pilots who think of the pitot heat as something you use if you're worried about icing but don't turn it on as a matter of course in low visibility or flying through clouds. It was kind of a LAMPS-ism but if you didn't have the probe heat on in the simulator and you flew through a simulated cloud, the sim operator would crash you by commanding the stabilator to program full retard, just as the aircraft would supposedly do if the airspeed input to the stab channels went wonky... or so the community superstitions would have us believe.

Icing was like a great unknown when I flew. Per NATOPS, you didn't fly in those conditions. If you were anywhere close, you turned on pitot heat, engine anti-ice (I think that was it). That was all you had.

I do know of a 53 driver out of Miramar who, bc of a bad ODO wx brief and a shitty OAT gauge, trying to get over the hill to Yuma training areas, unawares got iced up. He went on Mr Toad's wild ride through the clouds, at one point seeing the bottom of the meatball. He punches through the bottom of the layer, sees Gillespie Field, lands without talking to tower, shuts down, cleans his drawers, and calls base for a ride.

I'm fairly sure his pitot-static system froze up, while a boot copilot was at the controls, and they got into a weird attitude situation.

But, really not sure if there was any rotor blade icing involved. Probably not, but some of you test pilot types would probably know better.

 

[Jim123]

Icing was like a great unknown when I flew...

I think I wrote my post a bit ambiguously. I meant that we always turned on pitot heat in IMC in the 60 and that's always just been something I've done ever since. It seems strange to me that anyone would routinely leave it off for just about everything except for icing, yet there are occasionally guys who have stories about their airspeed going wonky and have "I didn't have the pitot heat on, do you think it would help?" kinds of questions. Things like that stump me why someone wouldn't have it on.

I do remember various NATOPS inadvertent icing conditions procedures to turn on pitot heat, sometimes phrased as "verify-on," I suppose in case you had forgotten it and possibly implying that it should already be on anyway.

 

[Brett327]

A couple of things to come out of the 60's FBW stabilator that have me puzzled about a handful of specific airplane crashes in the last few years-

With the now-infamous MCAS on the 737, all they had to do was build it using two completely redundant systems and build it to automatically shutdown both if they disagreed by more than a certain amount. I think I still remember that the tolerance on the -60 stab was if one channel disagreed with the other by 5-12° or something like that. Boeing could have averted a corporate disaster by just cribbing Sikorsky's notes from 1980 on their damn stab, which funny enough shared a broadly similar purpose- to make the aircraft "feel" a bit different.

Pitot heat 100% of the time in IMC. There are GA pilots who think of the pitot heat as something you use if you're worried about icing but don't turn it on as a matter of course in low visibility or flying through clouds. It was kind of a LAMPS-ism but if you didn't have the probe heat on in the simulator and you flew through a simulated cloud, the sim operator would crash you by commanding the stabilator to program full retard, just as the aircraft would supposedly do if the airspeed input to the stab channels went wonky... or so the community superstitions would have us believe.

Let’s be honest though. Having your stab program automatically at a prescribed airspeed is hardly a FBW FCS.

 

[Gatordev]

Pitot heat 100% of the time in IMC. There are GA pilots who think of the pitot heat as something you use if you're worried about icing but don't turn it on as a matter of course in low visibility or flying through clouds.

I do the same thing in GA. I can't think of a reason to not turn it on, other than forgetting to turn it off. FWIW, in the EC-135, pitot heat was always on. Period. I'm sure it was part of making sure the A/P and AFCS were fully functional for SPIFR. It was also amusing to watch smoke start to rise when sitting in a LZ, either because a rain drop would hit the tube, or something else would...I'm guessing a bug.

Let’s be honest though. Having your stab program automatically at a prescribed airspeed is hardly a FBW FCS.

It does more than that and has additional inputs and responses. It certainly isn't as complex as a Hornet's system, but it moves autonomously based off of aerodynamic, power, and rate inputs. While it's never something you pay attention to in the cockpit, it's constantly adjusting due to the weirdo Blade Element Theory that comes off the rotor head.

 

[Pags]

I do the same thing in GA. I can't think of a reason to not turn it on, other than forgetting to turn it off. FWIW, in the EC-135, pitot heat was always on. Period. I'm sure it was part of making sure the A/P and AFCS were fully functional for SPIFR. It was also amusing to watch smoke start to rise when sitting in a LZ, either because a rain drop would hit the tube, or something else would...I'm guessing a bug.



It does more than that and has additional inputs and responses. It certainly isn't as complex as a Hornet's system, but it moves autonomously based off of aerodynamic, power, and rate inputs. While it's never something you pay attention to in the cockpit, it's constantly adjusting due to the weirdo Blade Element Theory that comes off the rotor head.

Any risks that may be inherent in a FBW design are outweighed by the advantages in FC performance, ability to add/change capability, weight savings, etc. Legacy controls aren't without their risks either, it's just the devil that you know.

 

[Jim123]

Let’s be honest though. Having your stab program automatically at a prescribed airspeed is hardly a FBW FCS.

It's kind of FBW "lite."

It did have at least a couple other inputs though. I remember collective pitch being a big one and it would move a lot for that (especially when you entered an auto). Sideslip was another one (basically anything that affects the airflow on the stab, either from the rotor wash or from the slipstream/relative wind of the helicopter's flight path). The whole point of it was to keep the nose lower during dynamic maneuvering so you could see out front better—especially during an aggressive approach into an LZ—at least compared to conventional fixed stabs like the upside-down wing on the Huey. Overall I thought it was kind of a Rube Goldberg thing that did a better job than a fixed stab and it was an admirable engineering attempt to make the helicopter better at its mission, but I didn't think it wasn't worth the cost in spare parts, maintenance, and dispatch (no Huey or 53 ever scrubbed a mission for a stab amp, but at least for the Navy 60 that was a downer).

I will say that once they ironed out the bugs, Sikorsky got the common failure mode right by designing a very simple, obvious safeguard- i.e. if there's a fault then the system freezes in place and reverts to manual slew only. And in comparison, Boeing overlooked that obvious safeguard (and a few others) on their MCAS. It started as a really neat idea to use new technology to make the big airplane fly better and feel more like the little airplane from 50 years ago. They've successfully used something similar on one or two other types and it's a similar concept to the Sikorsky automatic stabilator (new tech to make the aircraft fly better, particularly in pitch feel). But they engineered their system with an unintentional but entirely foreseeable failure mode that let it run away, uncontrolled. Now, this isn't the whole story because you could always override a runaway MCAS by doing some very simple pilot 101 stuff (trimming the airplane... something the ET302 first officer utterly failed to do, and for whatever reason most of the aviation press doesn't hammer that point nearly as much as they should, but that's another discussion).

Anyway, as @Pags alluded about the "devil you know," everything on an aircraft is some tradeoff or another, and between the drawing board and when the system has been in service for ten or twenty years, sometimes it works out great and sometimes it's not pretty at all.

That's a complicated way of saying what I meant to say.

 

[Meyerkord]

For anyone interested... Ingenuity encountered 20+ degree oscillations caused by a single lost image from the navigation camera. This resulted in a mismatch between the images and the expected timestamps, resulting in the over correction of the controls. Was able to land itself safely.

In-Flight Anomaly Sends NASA's Ingenuity Mars Helicopter on a Wild Ride – Here's What Happened

On the 91st Martian day, or sol, of NASA’s Mars 2020 Perseverance rover mission, the Ingenuity Mars Helicopter performed its sixth flight. The flight was designed to expand the flight envelope and demonstrate aerial-imaging capabilities by taking stereo images of a region of interest to the west. In

scitechdaily.com

 

[JTS11]

Same happened to me on FAM-1 in the TH-57B. Timestamps didn't match up with my control inputs... luckily the IP brought us back to earth.

 

[taxi1]

This resulted in a mismatch between the images and the expected timestamps, resulting in the over correction of the controls.

Replace ‘timestamp’ with ‘tramp stamp’ and I was there in college.