Hovering references
 

Hey there,

any books or other literature out there about picking the references for hovering? The science behind it, the teaching and so on. Shawn had a bit in cyclic&collective, but for initial pilot training only. NVG brings own issues, vertical referencing for longline its own… anything about that out there?
A big thanks in advance!
cheers

ADS-33
 

You might have done l luck in a book about test flying and how the available cues in a particular environment are determined. As a starter for 10, you might search for ADS-33 which is the US Army design standard for helicopters.

In the section about usable cue environments, it discusses whether you have sufficient external cues to maneuver the aircraft increasingly aggressively (and it also describes the appropriate level of automation needed if you don't have the right cues). Whilst this doesn't specifically list that you need a two o'clock daisy it does give you a method for detmining if the environment you do have is enough.


https://cimg8.ibsrv.net/gimg/pprune....83945915de.jpg
Visual cue rating
So you go and fly in the environment you are interested in (say daytime in good light in the IGE hover) and you try various manoeuvres to see how good the cues are to maintain attitude and move logitudinally and laterally. Then you (and 2 other pilots) score it.

Then you take the scores and plot on the next graph.
https://cimg6.ibsrv.net/gimg/pprune....252f67549e.jpg
UCE
If your UCE is low then you have great cues and you should need minimal AFCS support (R22) but if your cues are poor (dust cloud, NVIS, night) your UCE will be high and you'll need much higher levels of AFCS support to achieve what you want (eg hover hold or groundspeed hold).

There's a lot more in ADS33 and its accompanying manual. Take a look

Great stuff, thank you very much! If anything more comes to mind, do tell.

We taught a selective radial scan on SAR which worked well for over water hovering when references can be poor.

It concentrated on the hover attitude and assumes you have a visual horizon. Looking out of the front gives you attitude, heading, lateral drift and some height information.

Then scan down through the AI and compass and rad alt to confirm what your visual references are telling you is correct and then a glance to the side to assess longitudinal drift.

Do this with minimal head movement if possible as that can disorientate you.

The scan can be adapted for NVG but requires more head movement.

You can do this IMC over the water using the AI and a doppler meter if you have one - or buy a modern SAR helicopter with auto hover.

Using the relationship between an object in the near to middle distance and another object further away can give excellent height references.

Thank you Crab! Any literature on that? Seems very interesting.

No literature sadly but it works - it is an extension of what most people are taught when learning to hover - use of the hover attitude.

I wish I knew the contact information for Larry Pravacek, who did the back seat flying to place the CN Tower in place. Larry had joined SA from the 101st in Vietnam, and after 7 or so years with us, left with the other S-64 team to work at Erickson. To this day I watch that video of him doing the tower and marvel at how smoothly it takes place, with ZERO references close at hand. If he or one of his compatriots reads this, perhaps they can suggest that he checks in here and describes how on earth he accomplished it.

It is impressive - I wonder if the precision work was done from the front or the rear facing stick controller?

Thats a good question in general, 212. There was another renowned S-64 pilot Bob Brown who espoused the left front seat and had modifications made appropriate to using that location. I know, from experience with Larry at SA, that he was a master in the back seat, and assumed he kept using those electrical ( thru the S-64 AFCS ) rear facing seat controls ( except for the collective, which was mechanically connected to the ship’s mechanical control system ), and used the superior wide open view of what was going on right in front and below.
Erickson also continued the work started by a senior engineer at SA, Al Albert* in designing a structural element “ accessory “ : to the airframe to enhance the stability of the load vs the helicopter. Erickson’s designs were in house, I believe, modified by field experience, and reflected structural integrity and engineering excellence. Certainly have stood the test of time.
* Al was the S-67 design chief as well.

For VR work the "reference" becomes the load which you fly as if it is the aircraft.

There will be a control delay which roughly equates to half the period of the pendulum which will increase as the line length increases.

A tip for height is if the conditions are suitable is to use the shadow of the load.

After a while it becomes second nature like a normal hover.

Longlining is a skill I never acquired, but always admired.

20 years ago, I flew as the panel-monitoring sandbag in a 212, while placing the letters "AMP" on top of the Centrepoint Tower in Sydney, 1000' up. No references at all anywhere near our height, he did it all looking down the 100' line via the left-side bubble. I was amazed at the rapid and large cyclic movements, though the aircraft itself moved position very little, apart from the attitude changes with cyclic.

Thank you guys, I really appreciate your input!