Those were the words that jumped out at me when I read this otherwise edifying article (H/T occasional reader Flatlander) about robot helicopters teaching themselves to fly:
Writing software for robotic helicopters is a daunting task, in part because the craft itself, unlike an airplane, is inherently unstable. “The helicopter doesn’t want to fly. It always wants to just tip over and crash,” said Oku, the pilot.
To scientists, a helicopter in flight is an “unstable system” that comes unglued without constant input. Abbeel compares flying a helicopter to balancing a long pole in the palm of your hand: “If you don’t provide feedback, it will crash.”
Ya see, this is what I’ve been on about: Airplanes want to fly. And they will, so long as Mongo can be taught to restrain his baser impulses. Helicopters don’t want to fly: They’re composed of a thousand moving pieces, each built by the lowest bidder, continuously enaged in patient, grim determined opposition to one another. At very high speeds, considering how slowly the whole Goldbergian aggregation mutters through the sky.
This is why, envious Kiwi chopper crooners notwithstanding, airplane pilots tend to be even-keeled models of social grace and optimism. While helicopter pilots – like their aircraft – tend to be a little, well: Inherently unstable.
Because it helps to be inherently unstable to pull off a stunt like this:
About 40 minutes following the crash (of his wingman in an Iraqi desert), enemy personnel suddenly appeared and began firing on their position. At this time, (CWO5 David) Cooper and his co-pilot were already starting up their engines to get an aerial view of the situation. Immediately upon taking off, Cooper’s aircraft became the target for enemy fire. Cooper flew his helicopter directly into the enemy fire, attacking the enemy positions and diverting fire away from the ground forces.
He landed his helicopter near the crash site twice during the engagement, where his fellow pilots downloaded ammunition and fuel from the crashed Little Bird and transferred it to his. These actions kept Cooper’s aircraft in the fight for as along as possible. After a third series of aerial gunnery attacks, the enemy personnel finally ceased firing and fled the area.
Lt. Gen. Robert W. Wagner, commander, U.S. Army Special Operations Command, described Cooper’s actions that day as seemingly impossible.
Of course it’s seemingly impossible. But rotary-wing aviators do the seemingly impossible every time they man up. They trust that once again, their whirling rotor blades will somehow not fly, so much, as to flog the air into submission.
Ah, backhanded compliment to those who thrive in the “constant input” environment….Actually, I always thought they used laser holograms and never actually left the deck.
the bad guys deliberately went out of their way to piss off a CWO5??!!! what were they thinking!
Sure. You can get away with this blatent disrespect now that you are retired. I can guarentee that had you said this while you were still deploying, you would have made the “No pick-up list.” of your local helo squadron.
Or the “Let’s dunk him three or six times before we reel him in” club
Aren’t the current generation of fighters also inherently unstable? I thought the fly by wire systems allowed the computers to keep the aircraft under control while the pilot directs the computers. I was thinking that started with the F-16, but I certainly could be mistaken.
NSDQ!
…to Jim Collins,
Run On Sentence follows: No disrespect to you, but one of the most bestest compliments an Naviator can give is to say in his best Friday after work T1600 O’Club drawl/horsevoiced howl/first toast of the afternoon, raising yer fist to the sky saluting the gall/spirit/memory/joy/honor of a brother in Service, especially a Rotorhead:
TO THE INHERENTLY UNSTABLE! That guarantees a hearty second, a true affirmation of all that we really do indeed respect in a slow moving, lightly armored, vulnerable weapon platform that no matter what YOU think, would pick a fellow airmen UP out of harms way.
v/r jug
Any one ever see the Harry Reasoner thing about helo pilots?
“That’s why being a helicopter pilot is so different from being an airplane pilot, and why in generality airplane pilots are open, clear-eyed, buoyant, extroverts. And helicopter pilots are brooders, introspective anticipators of trouble.
They know if something bad has not happened it is about to.”
The current Prime Minister of New Zealand before disbanding the strike wing of A-4 KAHU Skyhawks in 2001 called them “clapped out”. Now without a real combat capability we can ‘slow handclap’ the RNZAF helo dudes?
Pogue – the B2 comes to mind. Basically, the pilot’s control inputs are requests that the redundant flight control computers take into consideration (“thank you very much, now just sit tight for a sec while we decide if you’re trying to kill us all or not”). Once the FCC’s are all “thumbs up” on the pilot’s request, they take him on his way.
As I recall, the word on the B2 crash in Guam was that the FCC’s were getting bad (or no) data from some airflow sensors on the leading edge of the wing. There’s good (well, actually it’s pretty ugly) video out there of that crash.
As for the dissing of helo drivers – it kinda goes under that old saying that you don’t piss off the guy who packs your parachute
Brian
Pogue-
more stability = less maneuverability and vice versa.
SO…if you want to build an ass whoopin’ fighter, you want it to be able to turn on a dime and give you some change. Computers allow that. In a fly-by wire jet, you put in a “request”, via the “control stick” (aka “voting lever”). The various computers decide if what you want is possible and if so, what is the best way to achieve it. Por example: You are nose high and slow and want to roll right. Best way to roll when slow is rudders, but the “normal” way to roll is with ailerons. You (being a potato behind the problem) slam the stick right but the FCCs decide to use rudders to make the turn. You usually get what you want, but not always in the way you expect…
They built that fwd swept thing a few years back. Fwd swept wings verrrrry turny, not at all stable. Computer coughs, you are a tumblin’.
I think Brian is correct – lots of Guamian rain got in a pitot tube or a static port and sent bad Air Data to the FCCs. Plane couldn’t figure out how fast it was going and did it’s own thing.
Lex knows much better, but when I went to CQ in Hornet the first time we were told that off of the cat if the jet ain’t doing what we think it should be or if we do something with the stick and the jet doesn’t respond, our next move was for the handle between our legs. We have lost a couple of jets right off the cat for stuff similar to B2 crash.
Nose
Run-on sentence to commence: Regardless of how much muck the jet jockeys fling in the direction of the “inherently unstable” (hey, my husband resembles that remark…), said “inherently unstable” will still be there to sling the jet jockey’s sorry butts out of whatever mess they’ve managed to get themselves into
Like this.
Grew up in H-3 sqds in Jax, 80s. Several COs and more than a few DHs were HAL pilots missing the ole days a bit, and exercising the old frames prolly more than needed for stbd-d and sonobuoy drops. What a crew to live among and what an education for a wide-eyed lad’s first couple deployments. Inherently unstable indeed.
…sorry, and lest there be any misunderstanding, the closing comment above was uttered with the utmost respect.
it was a HAL-3 guy that made me want to become an aviator — instructor at the military Disneyland NROTC dept, he was the only guy I wanted to be like — FSU grad, BIG guy, big moustache, probably well outside regs. Always wore greens in the winter — certainly to piss off the shoes. I knew instinctively that I wanted to be around people like him. I could tell with him, it was mission first, do the rest, if it fit in — otherwise, screw it. Probably inherently unstable, but later experience showed he was within 1 std deviation of most naval aviators on the stability chart. Which is to say, about two away from the rest of the world.
Nose – I like your fly-by-wire explanation much better than mine.
Re the B2 crash – I’m not all that up on that a/c’s systems, but I think I read somewhere that they have something like 30 air flow sensors (not sure if they’re actually static ports or something else) all along the leading edge of the B2′s body to give the FCCs data on how air is flowing over the entire body. Some of those sensors are what I understood to have failed, aparantly without informing the crew. Can you shed further light on that?
R – Brian
When I went through the Huey frs in the mid 80′s the skipper was an HAL-3 guy. Then later at Pt. Mugu, HAL-5 was just across the street from us and I think some of their 5′s senior guys had some 3 experience too. A good bunch of guys that held their liquor well and told excellent stories. They even bought a round occasionally…
Sort of keeping with this theme, a friend I cruised with on Saratoga was a helo pilot, callsign “Wingnut”.
HFS, thx for the link, The cartoon is great!
Flat, I did 92 Sara cruise, when were you on her?
Brian,
I don’t know anything systems wise, but I did hear that the Guam heavy rain messing with the B2 systems was a known problem, but for some reason didn’t get passed down to the guys who had the jet crash.
Nice.
Nose, I cruised 83-84 and 85-86 on Sara.
Course I was only 2 years old at the time, more or less.
The USAF had gone back and forth about putting B-2′s Guam for a while-however a lot of the Anderson AFB Milcon budget was predicated on building facilities for them. Same was true for DGAR as I undertsand it-USAF did not want to do it-because of moisture concerns. I was in DGAR before OIF began and they brought these blow up shelters for the aircraft.
“He landed his helicopter near the crash site twice during the engagement, where his fellow pilots downloaded ammunition and fuel…”
Pardon my french but… Damn. Just, Damn.
Buy that man a drink on me and put him on plane guard when I’m in the stack. Hoo-rah, indeed.
unkawill, you might wanna check those bifocals.
Rotor heads are the ultimate best friend a fast mover can ever hope to have. That said, the best line I ever heard about flying helo’s was at the bar in Cubi a long time back, “Flying helo’s is like playing with yourself, it’s really a fun thing to do but you don’t talk about it in public”
HFS, I stand corrected.
Skippy-san, Good cartoon!
Hah. I finally thought of the algorithm for inherently unstable systems. Proportional Integral Derivative – P.I.D. All those unstable system use a learning mode that says for this movement apply this force, not linearly but proportionally. All the math makes my head hurt and my youngest nephew Ben could explain how all those numbers get to be where they are; when he’s not dropping electron microscopes on his body (really!). That’s also the science behind the Segway scooter. Amazing stuff that math, holding upright a two wheel vehicle with a 200lb doofus on it. Its also what overcompensated and turned a B2 into a bonfire in Guam. Oh, well. back to the whiteboard for the engineers……..
unkawill ~ I didn’t realize Skippy had posted a cartoon. I thought you mistook the image I linked to was a cartoon.
I want one of those Kimchee depth gages.
Mr. Coopper is a true stud, along with the reast of the people in the SOAR.
Holy Crap! His co-pilot had already previously eeceived a Silver Star! I had never heard that when this story first came out.
Big Brass Ones!
NSDQ
All this is at least a hundred years old. Wilbur and Orville knew how to build an inherently stable airplane, but deliberately chose to make an inherently unstable airplane, counting on developing their skills to keep it pointed the right way. They had inherently stable helicopters as toys, when kids. I’ve built replicas of them.
When Lindberg was having the Spirit designed, Ryan was going to increase the tail volume to account for a bigger wing, but Lindberg told him to leave the empennage the same size, so he’d have to actively fly the thing all the time. He thought that would help keep him awake
Should I worry when the “Firescout” flies over me house? LOL.
b2
Thanks for the Reasoner cartoon, Skippy; I sent that link to my old high-school buddy, the retired Pave Low pilot. My first flight instructor was a retired VN-era Army Aviator, and I’m pretty sure it was impossible to scare that guy – although I certainly did my best on a few occasions.
A humble correction to Nose’s comment on the X-29 (They built that fwd swept thing a few years back. Fwd swept wings verrrrry turny, not at all stable).
I worked on the X-29 back before they ripped up the runway at Bethpage and built a bean processing factory. Forward swept wing A/C are not inherently unstable. We built the X-29 with a negative static margin to increase maneuverability, but the forward swept wings were intended to drastically reduce transonic drag and (IIRC) give us a better transonic L/D. The A/C instability came from the relative positions of the Cg and Cp, not the wing sweep.
The real challenge with forward swept wings is structural. Without sufficient stiffness they diverge very rapidly and depart the a/c which is, to say the least, inconvenient. Composite materials finally made it possible to build a wing with sufficient stiffness without a prohibitive weight penalty.
That being said, the X-29 was, I believe, the first a/c designed with such a large negative stability margin (-30% IIRC).
I once ran our maneuver simulation software without the FCS subroutines, and it showed the a/c performing several 360 deg. pitch excursions in 2 seconds (not physically possible, but the s/w didn’t know that).
We used to joke that the FCS computers should be hooked directly to the ejection seat, and that the mission objective was to pull 1 g more than the F-5G at 0.9 M/30 k ft.
Thanks Paul. If you hang around here long enough, you will find that I am basically pretty ignorant and usually have no pecking idea what I’m talking about.
Interesting stuff.
Nose
But Mongo likes his baser impulses, Lex!
I’ll pass along here an oft forwarded story about helicopters and their pilots:
Helicopter flight: A bunch of spare parts flying in close formation.
Anything that screws its way into the sky flies according to unnatural principals.
You never want to sneak up behind an old, high-time helicopter pilot and clap your hands. He will instantly dive for cover and most likely whimper…then get up and smack the shit out of you.
There are no old helicopters lying around airports like you see old airplanes. There is a reason for this. Come to think of it, there are not many old, high-time helicopter pilots hanging around airports either so the first issue is problematic.
You can always tell a helicopter pilot in anything moving: a train, an airplane, a car or a boat. They never smile, they are always listening to the machine and they always hear something they think is not right. Helicopter pilots fly in a mode of intensity, actually more like “spring loaded”, while waiting for pieces of their ship to fall off. Flying a helicopter at any altitude over 500 feet is considered reckless and should be avoided. Flying a helicopter at any altitude or condition that precludes a landing in less than 20 seconds is considered outright foolhardy.
Remember in a helicopter you have about 1 second to lower the collective in an engine failure before the craft becomes unrecoverable.
Once you’ve failed this maneuver the machine flies about as well as a 20 case Coke machine. Even a perfectly executed autorotation only gives you a glide ratio slightly better than that of a brick. 180 degree auto rotations are a violent and aerobatic maneuver in my opinion and should be avoided.
When your wings are leading, lagging, flapping, precessing and moving faster than your fuselage there’s something unnatural going on. Is this the way men were meant to fly?
While hovering, if you start to sink a bit, you pull up on the collective while twisting the throttle, push with your left foot (more torque) and move the stick left (more translating tendency) to hold your spot. If you now need to stop rising, you do the opposite in that order. Sometimes in wind you do this many times each second. Don’t you think that’s a strange way to fly?
For Helicopters: You never want to feel a sinking feeling in your gut (low “g” pushover) while flying a two bladed under slung teetering rotor system. You are about to do a snap-roll to the right and crash. For that matter, any remotely aerobatic maneuver should be avoided in a Huey.
Don’t push your luck. It will run out soon enough anyway. If everything is working fine on your helicopter consider yourself temporarily lucky. Something is about to break.
Harry Reasoner once wrote the following about helicopter pilots:
“The thing is, helicopters are different from planes. An airplane by its nature wants to fly, and if not interfered with too strongly by unusual events or by an incompetent pilot, it will fly. A helicopter does not want to fly. It is maintained in the air by a variety of forces and controls working in opposition to each other, and if there is any disturbance in this delicate balance the helicopter stops flying; immediately and disastrously. There is no such thing as a gliding helicopter. This is why being a helicopter pilot is so different from being an airplane pilot, and why in generality, airplane pilots are open, clear-eyed, buoyant extroverts and Helicopter pilots are brooding introspective anticipators of trouble. They know that if something bad has not happened, it is about to.”
bc,
What squadron? We might have crossed paths a few times. I was with HS-15 from May 84- Nov 87.
Some Rotorhead History
Jim Collins:
I hope you calmed them down some. I was in the same Air Wing with them until May 84. The Red Lions were the wildest bunch on the ship.
Can’t remember the exact details, but Harv Fielding (CO) did one nifty piece of flying during the Grenada thing.
xairboss,
I got there just as you left. Quiet that bunch down, you have to be kidding. Wasn’t much I could do as an E-3 Mech. I was at the ceremony where Cdr. Fielding got the DFC. I never did get the exact story of what happened. By the time I got there, it was pretty much a legend and I was never sure which part was truth and which part was sea story.