Height-Velocity / Deadman's Curve
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- เผยแพร่เมื่อ 16 ก.ย. 2024
- Welcome back! I'm Jacob and in this video I cover the Height-Velocity Curve, also known as Deadman's Curve.
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Just about every operator's manual has a diagram that depicts airspeed in relation to altitude and calls it either the Height-Velocity Curve, the Avoid Region, or Deadman's curve. Generally it outlines the area of certain altitude and velocity combinations that you want to stay away from because, if an engine fails, the likelihood of safely landing is unlikely. Each chart should be tailored to a specific aircraft. The reason you want to avoid operating in this region is because there simply isn't enough kinetic or potential energy in the form of airspeed and altitude, respectively, to safely autorotate. In this video I'd like to outline what the curve is based on, what isn't mentioned or explained, and some considerations.
First off, the chart is based on a few factors. To be certified, the curve must e demonstrated under the helicopter's maximum gross weight. This is so the worst-case scenario is what is depicted. Anything lighter weight would be a shrinking of the curve. Second, the curve is based off of the average pilot. This doesn't mean a pilot or training but instead a proficient pilot who can perform basic emergency procedures. Above the knee part of the curve, there is usually a 1 second delay factored in between onset of engine failure and the pilot inputing the corrective action. That said, highly experienced pilots have been known to "beat the curve" and safely recover the helicopter despite being inside the curve. I wouldn't recommend ever pushing your luck here because this is done by trained pilots who know the exact indications and symptoms of an engine failure (usually seconds before it happens) and react instantly with the corrective action as if they'd been spring loaded to do so.
Moving on to what the chart doesn't show. Most of this testing to determine the curve involves a run-on or roll-on landing to a suitable landing area. If you're not over a flat runway, theres no guarantee your autorotation will be survivable. Furthermore, just because you are outside the curve doesn't mean you're necessarily safe either. While being outside the curve you could still have an engine failure over a wooded area, lake, or rocky terrain. Being outside the curve just means you have the potential to make it to the earth's surface in a controlled fashion instead of an uncontrolled plummeting. Lastly, not all charts account for pressure altitudes. In fact, many are based on sea level altitude. By flying in higher altitudes, the curve expands right and up to cover higher airspeed and altitude combinations.
The last thing I want to cover is other considerations such as the high-speed low-altitude region that is sometimes present. This is for pilots operating so low and fast that a pilot might not have enough time to safely react to an engine failure and recover in time. Also, dual engine helicopters usually have a smaller curve depicted. If 1 engine fails, the helicopter may still maintain flight if outside of the dual engine curve. But if the second engine fails (for instance because of a fuel issue) the helicopter would still need to be outside the single engine curve. Lastly, some federal regulations outline that intentionally operating in this avoid region is breaking an aircraft limitation and therefore should be avoided at all times. But this usually applies to larger, heavier, multi-passenger helicopters and not your typical commercial one.
That wraps up this video. The Height-Velocity Curve or Deadman's Curve is simply an area that you may want to avoid or not linger in because its unlikely you can safely recover the helicopter if you lose an engine.
Be sure to hit like and subscribe below. Once again, I'm Jacob and this is Helicopter Lessons in 10 Minutes or Less. Safe flying.
The best training videos for rotary wing flight I have watched. Having watched them all I would love an advanced series of lessons that go in depth and extend the discussion.
Interesting. I took a tour in an AS350 recently and sat in the front so I could observe the instrumentation. Pilot said you need three things to fly a chopper -- 1) brains, 2) speed when low, 3) height when slow. He said that as we went down low and fast following a river. I instinctively understood what he meant by that but did not mentally graph that as you explain here. Thanks for all your explanations. 👍🤠
Video day....great content as always...u r doing a fantastic job jacob,😎✌️
As someone who operates in Papua New Guinea and always operating on the very edge of the deadman’s curve, this video is a really good explanation for new pilots entering the industry.
Love it bro. You're videos have gotten me through the SIFT, all the way through the 64E course, and even now at my first Aviation unit!
I’m in the process of putting together my WOFT packet, and I’ve been constantly studying the SIFT Guide. What tips can you give me to increase my chances of selection? Also, how can I excel during flight training?
keep on learning. thank you.
You make the ground lessons I've come across, Well Done!
👍 well done. Great content
Great video lesson sir. As always, thank you.
Great Job as always. Thank you.
Clear and concise. Great video!
Something to remember about this is that not always you can stay out of that greyed-out area. For example a single engine heli doing utility work or firefighint has to hover to attach/detach the cargo or load the bucket with water and you will be forced in that area. Ofc you don't want to hover for 10 minutes at 150ft just because you want to.
Now, i'm not a pilot and if i'm wrong please correct me.
Daniel Helicopters Photography. I completely agree. Many helicopters have to operate in this zone as part of a job. But lingering in this area for no legitimate reason shouldn’t be done. And if you have to operate in this region the pilot just needs to be hyper aware of any malfunction in order to react as quickly as possible. Thanks for the feedback!
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This is also a good reason to do a thorough pre-flight inspection. SAR, Search And Rescue missions most of the time operate in the Dead Man's curve, so it essential to do a thorough pre-flight on these choppers. Mechanical, Electrical, hydraulics, fuel, proper gear, weight n balance, instruments, etc. You want to make sure the chopper is air worthy n good to go.
You also need to have good CRM, Crew Resource Management skills, where everyone knows their jobs n how to communicate effectively...
Dude! That 'Not explained' part is GOLD! The rest of it too, of course ;)
Thank you very much Jacob!
Fantastic video!
well-explained Jacob...
Excellent one as always. Thanks very much indeed. Waiting for the "Advanced Autorotations" vedio. Particularly, interested about "turns" in Autorotation. Why the NR increases and decreases in turns and all those staffs. Thanks very much in advance for forthcoming vedios. Cheers.
Raihan Shuvo. It’s still on the list and I apologize for the delay. I’ve had quite a bit of videos requests. Thanks for the feedback!
I'm binging these videos in order while working my day job and sometimes can't see the title...
*Music starts*
Me: Ooo, this must be serious
Jacob: I'll be talking about the height velocity curve. Also known as the DEAD man's curve
Me: 😵 Oh. Nice.
Thanks so much for these videos Jacob! They are clear and concise. I'm in the process of relocating states to become a pilot. Keep it up and fly safe out there!
Good vídeo 👍🏾🚁
Always good,
Hi good night excellent video, can u do a Video on the power curve.
Couple of things: First, I like the beginning of your videos showing the Unicorn...an Apache actually that is actually FMC...LOL. Secondly, in a dual engine aircraft that chart has nothing to do with autorotation. It is a single engine failure chart. In the Blackhawk it is set for 15°C, sea level and a 0.85 EFC. It has multiple weights and different curves for each. The Lakota it allows for different PA and Temperature conditions. You can interpolate between the different weights. The top of the curve is the minimum height you need to be at, in order to accelerate to a minimum single engine landing speed. The knee is that minimum single engine airspeed.
Ray Blevins. Glad I could let you see the unicorn in flight haha. Well said on your second part. I believe I outline in the video about how it is different for dual engine conditions but thanks for adding that in. Most Army helicopters have charts for varying conditions but some civilian charts are bare bones and leave the pilot lacking quite a bit of clarity. Thanks for the feedback!
dave sniw thanks for putting me in my place.
Helicopter Lessons In 10 Minutes or Less, I provide your link to my students. I just felt the info could have been presented differently. Keep up the good work.
I would think on newer helicopters with glass cockpits they could either display the curve with helicopter location on the curve or at least display a warning light when in the the danger zone (assuming you have input the current load weight)?
Tom Mendenhall. I don’t think it would be hard to put in some sort of advisory like that. Most military helicopter pilots are taught about this zone early on and its importance is instilled in you over and over through emergency procedure training. I can’t speak much on civilian flight instruction however. Thanks for the feedback.
Where can I purchase it books in australia
Could you do a video on recirculation of air in IGE & how that can cause loss of lift?
I’ll add it to the list!
As one of my Marine IP told me in flight school, don’t be low, slow and stupid. Always maintain your Jesus factor.
Valuable info! 🚁 😭 🚑
👍☝🤜
Was this @ Ft. Polk?
This made me think of my economist class
T
Oh no I’m out of videos now, I need more!
Austin Taylor. I generally try to put out videos every 2 weeks or so. Stay tuned. I promise there'll be more!
Helicopter Lessons In 10 Minutes or Less awesome! I can wait to see the next one