What happens if Marine One's rotor blades fail?

Question

While I was reading news, I came across this image of Marine One:

On a closer look, I see there are two big exhausts just under the blades at the top of Marine One. And there is also a big wing at the end of Marine One.

I know I would be wrong, but I am not sure about it: I thought these two things are inter-related to each other in case of rotor failure, i.e if the rotor fails then the exhaust would pump out air backwards like a blast giving it forward thrust, and the wing at the end would help it in direction or upward/downward thrust balance (just like in F1 racing cars). Essentially making it work like a plane for some time until it lands safely.

I tried searching about it, but could not get information about it. I did come across an older Marine One image whose exhaust is too small and is at the side rather than at the back and this does not have a wing at the back:

This is Sikorsky SH-3 Sea King

Citation of Image 3 Citation of Image 4

I have 3 questions:

Why is the exhaust at the back of new Marine One so big now?
Why is there a wing at the back of the new Marine One ?
What would happen if rotor blades of Marine One fail ?

Citations

Welcome to Aviation.SE! If the rotor blade fails (comes off/breaks), the helicopter will crash. The exhaust nozzles do not provide lift and the tail doesn't either. I think somebody should be able to give you a good answer in detail. — Ron Beyer, Jul 17 '17 at 17:35
See https://en.wikipedia.org/wiki/United_States_presidential_line_of_succession. — Fred Larson, Jul 17 '17 at 18:05
@FredLarson Doing a Ctrl+F, then typing Marine One and hitting Enter does not show any mention of Marine One on the page you mentioned. — GypsyCosmonaut, Jul 17 '17 at 18:10
Meaning if the rotor of Marine One fails, the presidential line of succession comes into effect. — Fred Larson, Jul 17 '17 at 18:14
Hahahaha.. Okay, got it. But then what is the use of that big exhaust and big wing at the back? — GypsyCosmonaut, Jul 17 '17 at 18:15
This helicopter is a (slightly modified) black hawk. You can now search what you want about this helicopter and ask questions about specific parts of it (either the regular version or the one for the US president) — Manu H, Jul 17 '17 at 18:25
@GypsyCosmonaut: Should it? Or are you making the mistake of assuming your particular browser's search command (which is what I'm guessing the Ctl-F is supposed to be) is universal? — jamesqf, Jul 17 '17 at 18:33
@ManuH Thanks. But I'm not sure if someone is right now typing an answer to this question or not, if I delete the question and they have typed a long answer then it might be a waste. I would ask specifically if I do not get an answer to this. — GypsyCosmonaut, Jul 17 '17 at 18:40
You might get some info on the "big wing" here: https://aviation.stackexchange.com/q/25308/520 — Fred Larson, Jul 17 '17 at 18:56
The two large exhausts just below the rotor pointing back serve the exact same purpose as the ones pointing to the side do on the older helicopter - to exhaust burnt fuel from the twin turbine engines that provide power to spin the rotor shaft. Aiming them backwards vs sideways is simply a design decision made by the manufacturer when balancing out all the other design decisions that needed to be made. While there is some force from the hot exhaust gas, it's negligible in terms of what is necessary to move the bird or keep it flying. — FreeMan, Jul 17 '17 at 20:43

score 23 · Accepted Answer · edited May 22 '18 at 06:33

23

No helicopter can fly if the blades fail. The overwhelming majority of the lift produced, required to counter gravity, is from the blades. There is some lift from lots of other parts of the helicopter but all combined, nowhere near enough to keep it flying. The blades are also required to manoeuvre the helicopter.

It is also most probable, and this what usually happens, that if one blade fails, or is lost, the resulting imbalance in the heavy, fast rotating rotor assembly leads to instant breakup of the aircraft.

The wing at the rear is called an horizontal stabiliser and its job is to push the tail up or down, depending on the load and speed of the helicopter, to keep the fuselage more or less level throughout the operating range of the craft.

Marine One would simply plummet if the blades failed.

edited May 22 '18 at 06:33

Federico

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answered Jul 17 '17 at 20:12

Simon

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Okay.. Thank you. My question has gained some negative feedback. How can this question be improved so as to help the community ? Or shall I delete it because this is just another stupid duplicate question. – GypsyCosmonaut Jul 17 '17 at 20:21
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Neither. I don't know why it's been downvoted and it's not a duplicate. Quite simply, no-one has asked this "obvious question" before so it belongs here. I am very much of the school there are no stupid questions; perhaps not right time, right place but if this is not a place where someone who does not understand can ask these questions, then where is? +1 from me to help the natural balance of the interwebs. – Simon Jul 17 '17 at 20:36
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Blade failures are one thing that is not trained, discussed or thought about since every helicopter pilot knows, unless they are slow and close to the ground, that they are dead if it happens. Not nice reading, but this is typical of what happens. P.S. you really need to edit your question to provide the attribution to the images. We are big on crediting sources here and it's possible some people might downvote because of that. – Simon Jul 17 '17 at 20:40
Finally, I don't see what's wrong but if you want advice, by all means try asking here – Simon Jul 17 '17 at 20:43
Another +1 on citing image sources. – FreeMan Jul 17 '17 at 20:45
Full disclosure - the "Not nice reading" link apparently needs access, which I seem to have via my employer, even though I didn't realize I had until I clicked. (Circular logic is circular) – FreeMan Jul 17 '17 at 20:47
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@FreeMan Ah, yes, I was only reading the summary. I think this accident report is accessible without restriction. – Simon Jul 17 '17 at 20:59
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@Simon I did all the citations now. I did not know it was that important in this community. Thanks for helping – GypsyCosmonaut Jul 17 '17 at 22:03
Well, on a different question on here, I was informed helicopters could safely land if the engines failed... – Cloud May 22 '18 at 10:14
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@Cloud Engine failure and rotor (or blade) failure is not at all the same thing. – user May 22 '18 at 12:59

score 14 · Answer 2 · answered Jul 18 '17 at 13:47

To answer the other questions...

Why is the exhaust on the Blackhawk so much larger than the Sea King? One reason is - the Blackhawk has larger engines, 1500hp as opposed to 1200hp. The primary reason, though , is dispersing the exhaust heat, making the Blackhawk a harder target for heat seeking missiles. Note the fairing above and around the exhausts, also part of the heat disperson system.

Why does it have a wing on the back? This Q/A thread suggests it is tied to airspeed, not the cyclic, for stability reasons.

As for a main rotor blade failing... yes, you're pretty much dead if that happens. One reason helicopters cost so much more per hour to operate than aircraft is the more rigorous maintenance and inspection schedule, especially on the main rotor and blades. Fortunately, main rotor failures outside of the blades hitting something due to pilot error are extremely rare.

According to Wikipedia, the current generation UH-60L's have two General Electric T700-GE-701C turboshaft engines, producing 1,890 hp each. https://en.wikipedia.org/wiki/Sikorsky_UH-60_Black_Hawk#Specifications_.28UH-60L.29 — SnakeDoc, May 22 '18 at 16:00

score 14 · Answer 3 · edited Dec 04 '17 at 06:08

I served as a Helicopter Crew Chief on a Sikorsky H-34 helicopter in Vietnam and I agree that blade failures are incredibly rare on properly maintained aircraft.

On most helicopters the main structure of the blade (spar) is hollow and contains pressurized gas — usually nitrogen. Before each flight, the Crew Chief and Pilot check a gas pressure indicator on each blade. If a crack develops in the blade, the gas will leak out and likely indicate a problem before there is a failure.

Military helicopters are designed to work very hard and handle a great deal of stress. Marine One probably has a very easy life compared to its counterparts in the rest of the world. I’d say it is a very safe aircraft.

What happens if Marine One's rotor blades fail?

3 Answers3