1972: Autogyros

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Autogyros

Title text: I understand modern autogyros are much more stable, so I've probably angered the autogyro people by impugning their safety. Once they finish building the autogyros they've been working on in their garages for 10 years, they'll come after me.

Explanation

This explanation may be incomplete or incorrect: Have created sections for explaining each of the statements, but they need to be expanded. Do NOT delete this tag too soon. If you can address this issue, please edit the page! Thanks.

Randall has been looking at the facts about autogyros, hence the title of the comic. He has drawn Megan flying in such a vehicle with several statements of the facts he has unveiled.

Randall states that an autogyro is nothing like a helicopter (which it looks like), nothing like a plane (but flies like one) and works like a powered parachute (without anything looking remotely as such). He continues to make a total of 12 statements which will be explained individually below.

The final statement at the bottom right is the punch line of how strange these flying machines are, because they are safe, as long as you do not do what a pilot instinctively would do in a plane in case of a stall, because if you do so the autogyros will crash immediately... See the explanation below. That sentence is almost rendered unnecessary by the one above it that states that autogyros never stalls!

Randall's conclusion is clear: Autogyros are weird.

In the title text Randall continues on the last statement by saying that today autogyros are much more stable. Which must refer to that this was not always the case. And this new stability probably means that a stall situation is much less likely and the last statement is then not so relevant anymore.

Randall then goes on to suggest that the autogyro people will be angered by this comic, which impugns (i.e. attacks) the safety of their beloved machines. But he keeps on mocking them. In fact, he states that they will come after him, once they have finished building the autogyros they have been working on in their garage for the last 10 years. By this, he implies that the people who work on them do this as a home garage project so they will never get them finished and able to fly. Thus, they will probably never come after him.

Statements

• Below each of the statements in the comic are explained
  • The optimal reading order is to read them in the four columns they are arranged in:
  • The left with four, the two single in the middle and the six on the right.

Nothing like a helicopter

Looks like a helicopter, but is nothing like a helicopter

It is like a helicopter in the sense that a horizontally spinning fan provides the lift. It is unlike a helicoper because A) the fan is not powered, B) the fan does not provide forward propulsion, C) it is incapable of hovering, or moving in any other direction than forward.

Nothing like a plane

Flies like a plane but is nothing like a plane

Its flight pattern resembles a plane in that it can only move forward, turns by banking, and needs to maintain forward velocity in order to create lift. However, unlike a plane it has no wings to generate that lift.

Powered parachute

Sort of like a powered parachute

Rare in the US

Rare in the US, usually homemade. Common in Europe.

Big blade on top

Big blade on top is not powered and spins freely

Flown without a license

Can often be flown without a license

Cheap

Helicopters are notorious for being extremely expensive to operate. At a typical general aviation service in the US, a two-seat aircraft may rent for under $100/hr, while a helicopter runs over $200/hr. Similarly, a small used helicopter may cost almost $200,000 while a small new autogyro may cost under $25,000. Since many people home-build their autogyros, it would often be even cheaper.

Needs a runway to take off

Needs a runway to take off, but not a long one

Can land vertically

An autogyro can land vertically: for that matter, so can any airplane. What matters isn't ground speed but airspeed, and as long as there's as much headwind as the landing airspeed of the aircraft, it will land vertically. Now, with fixed wing airplanes the landing speed is at least 40-50 mph, and you don't often find headwinds like that. The much lower landing airspeed of an autogyro makes vertical landings feasible.

Cannot hover

True hovering would require the rotor to be powered. However, an autogyro must be moving forward in order for the rotor to generate lift.

Never stalls

Most conditions that would cause a stall in a fixed wing airplane such as low speeds, high-G maneuvers, and gusty winds don't apply to autogyros. The rotor in an autogyro is in equilibrium, the inner, slower part is stalled, the middle part makes it spin and the outer, faster part slows down the rotor and provides lift. As the angle of attack increases, a fixed wing aircraft would stall, however, on an autogyro, it will just make the lift-generating area smaller, causing the rotor to automatically spin faster and the equilibrium is restored. This is not entirely correct however. If you reduce the forward speed of an autogyro, the rotor slows down, reducing lift so the autogyro will descend. Under most circumstances, this would lead to a controlled landing. However, if it happens at high altitude, you can run out of lift completely while still high above the ground causing a stall. This is more likely to happen if there is a strong tailwind.

Extremely safe

Extremely safe, unless you do the one thing you instinctively do to escape a stall in a normal airplane, in which case it will crash immediately

On a normal airplane, one will push the yoke forward in a stall or engine out situation, to regain airspeed and to stabilize the plane. On an autogyro, this leads to negative angle of attack, decelerating the rotor, which may lead to a crash. Also pushing the yoke hard forward while flying full throttle may lead to a crash.

Transcript

[A picture of Megan wearing aviator goggles, sitting in an autogyro and holding the control stick. The autogyro is surrounded by sentence fragments, explaining characteristics of it. The one above the blade that concerns the blade has an arrow pointing from the text to the blade. The sentences in columns from the left (i.e. left sentences first, then the two above the autogyros body and finally the sentences to the right):]

Looks like a helicopter, but is nothing like a helicopter

Flies like a plane but is nothing like a plane

Sort of like a powered parachute

Rare in the US, usually homemade. Common in Europe.

Big blade on top is not powered and spins freely

Can often be flown without a license

Cheap

Needs a runway to take off, but not a long one

Can land vertically

Cannot hover

Never stalls

Extremely safe, unless you do the one thing you instinctively do to escape a stall in a normal airplane, in which case it will crash immediately.

[Caption below the panel:]

Autogyros are weird.

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Discussion

Land vertically?

Hi, searching 'autogyro' has led me to find autogyros can't land vertically. Could this be a mistake on Randall's part, or am I missing a joke here?

172.69.186.58 13:55, 26 March 2018 (UTC)

I just read about them on Wikipedia and I see that they can't take off vertically, but there are kinds (possibly all) that can land vertically 108.162.219.76 14:01, 26 March 2018 (UTC)

The Wikipedia article was edited this morning to claim that they could not land vertically, but the edit was short-lived and reverted. So, be careful what you trust. JohnHawkinson (talk) 14:37, 26 March 2018 (UTC)

It appears they can land vertically with the correct wind conditions. Here is a YouTube video: https://www.youtube.com/watch?v=GAoK9zM8FFQ - and they say "Actually it is a 'Zero GROUND Speed Landing' approx. 25 kts headwind".

Here is a YouTube video of a zero ground speed takeoff: https://www.youtube.com/watch?v=Kd7_V4pW--Q

I think the confusion here is that yes, it can land vertically: for that matter, so can any airplane. What matters isn't ground speed but airspeed, and as long as there's as much headwind as the landing airspeed of the aircraft, it will land vertically. Now, with fixed wing airplanes the landing speed is at least 40-50 mph, and you don't often find headwinds like that. The much lower landing airspeed of an autogyro makes that feasible. Gbisaga (talk) 21:26, 26 March 2018 (UTC)

"Landing vertically"...having so little forward airspeed on touchdown that it is negligible108.162.216.208 23:40, 26 March 2018 (UTC)

I disagree with this. If that were the case, an autogyro could NOT land vertically or anything close to it. I think it's clear that "vertical" refers to movement relative to the ground, as movement relative to airflow is invisible. I'm having a hard time finding hard numbers on minimum airspeed for an autogyro (and unlike fixed wing aircraft, I've never flown one myself, so I don't have practical experience to fall back on). However I've seen a typical autogyro's best rate of climb speed is 50-50 mph, versus almost 70 for a 152; so I'll project about 30 mph for a minimum speed in landing configuration. Landing in that kind of headwind is certainly not unreasonable (though it would probably be not that much fun). Gbisaga (talk) 12:56, 27 March 2018 (UTC)

I'd expect an autogyro to be capable of landing the same way a helicopter with an engine malfunction lands - autorotate the rotor to store energy and then stop while relying on the rotor to slow the descent. Does not sound like the safest of procedures, but it certainly gives you a vertical landing. Mat (talk) 08:30, 27 March 2018 (UTC)

Doesn't the downward motion of the autogyro during descent contribute to the autorotation of the rotor, thereby providing lift while descending even through air that is calm laterally? 162.158.154.43 14:29, 27 March 2018 (UTC)

Thanks for the comments, guys. I'm not the original commenter, but I had a severe misunderstanding of what "landing vertically" meant. 172.68.26.71 13:54, 27 March 2018 (UTC)

Cannot hover?

I would assume that autogyros can hover in some conditions (i.e. in a headwind). This is the same argument as the one for "Land Vertically?"; namely that it's the wind that matters. Is Randall wrong here or is this just an impractical edge case? Here is a YouTube video Kosak2000 (talk) 15:58, 27 March 2018 (UTC)

It can hover in the sense that any fixed wing airplane can hover - by having a fast enough headwind. I've "hovered" in a Piper Cub before - even flown backward! But that isn't the conventional use of "hover" by aircraft pilots. Hover it meant to refer to purposeful powered flight over a stationary spot 'with no wind'. Such as a Helicopter can do. An autogyro cannot do this, as it must maintain forward movement (compared to the air) to maintain lift. However, with some "trick piloting," you can vertically land an autogyro. You're not hovering because you're not holding your altitude, but if you come in with some forward speed and high-ish descent rate, you can flare a few feet above the ground to a horizontal stop, turning your formerly forward speed in to slowing the descent rate to an acceptable descent rate to land at. 172.68.174.94 03:21, 28 March 2018 (UTC)

Trivia

First successful flight of an autogyro was in 1923, so they have been around for close to 100 years. Rtanenbaum (talk) 17:04, 26 March 2018 (UTC) The 1981 movie Mad Max II prominently featured an autogyro as part of the action. Rtanenbaum (talk) 17:04, 26 March 2018 (UTC) Also James Bond 007 flew the autogyro 'Little Nellie' in " You Only Live Twice". Reputedly prompting a bit of an autogyro revival. RIIW - Ponder it (talk) 17:46, 26 March 2018 (UTC)

There was also an autogyro in the 1980 adaptation of Ray Bradbury's "The Martian Chronicles" --Mr. I (talk) 00:51, 30 March 2018 (UTC)

First of all, I've converted section headings to bold labels - we should avoid them in discussion content. Secondly, my take on how to order the labels around the autogyro is down the left side, then across the top, and finally down the right side. I realize it's entirely up to the reader, but that order makes the most sense to me instead of clockwise - the text on the lower-right seems to be climactic in a strange Randell-esque way. Ianrbibtitlht (talk) 18:15, 26 March 2018 (UTC)

Agree with your entire comment, and have changed the order in the transcript --Kynde (talk) 20:03, 26 March 2018 (UTC)

Has Megan been seen wearing goggles before? Herobrine (talk) 23:05, 26 March 2018 (UTC)

"Powered parachute"? Sounds to me like this awesome thing. Fabian42 (talk) 08:50, 27 March 2018 (UTC)

It's actually this similar awesome thing and I've updated the main descriptions to link there. -boB (talk) 20:14, 27 March 2018 (UTC)

Section Headings

Re-converted section headings to bold labels in discussion content - please avoid re-adding them because they can interfere with auto-layout templates in the explainxkcd page system. Ianrbibtitlht (talk) 17:04, 27 March 2018 (UTC)

I feel like the "Not popular in the U.S., popular in Europe" should say "Self explanatory", then link to a page showing stats about popularity. (I can't find anything quickly, and am in a hurry right now). NiceGuy1 (talk) 07:19, 30 March 2018 (UTC)

Stack Exchange question

FYI: This xkcd was a subject on the Avionics Stack Exchange site: Is this XKCD comic list about autogyro features accurate? --PeterMortensen (talk) 12:46, 30 March 2018 (UTC)