Auto Hover

[EtherealN]

If I bank the heli it turns which I dont know if Im missing something here cause I fly rc helis and banking does not change the heading unless I am in forward flight and the weather vane effect begins.

 

Not that it is necessarily directly applicable to this situation, but I would caution you against taking advice from how a small RC heli behaves to infer behaviour of an 8 tonne aircraft. The effects of mass on momentum scale up real fast in this wherefore you most definitely will not see any "real" helicopter perform the way an RC heli does. Another example would be my RC Cessna, which did wingovers, barrel rolls, loops and all kinds of such fun stuff until I flew it into a tree. (Oops.) The only behaviour it had in common with the real Cessna was the tree thing, though I've never done that in a real one. (Besides, real cessnas are so boring I dunno if I'd want to get more time than necessary in them. :P )

 

This is also the reason why a small insect can take a fall 200 times it's height whereas humans might break apart from falls as short as once or twice our height. Things just doesn't scale linearly.

[Frederf]

I've discovered that my earlier statement is incorrect. The DT-DH switch or the PVI-800 task light status does matter outside of ROUTE mode with regards to being able to set your heading hold direction with the trim button.

 

The lesson: If you want to set your own heading hold direction while in autohover, you cannot be in DH or DT mode or you have to extinguish the active PVI-800 task light.

[sweinhart3]

I've discovered that my earlier statement is incorrect. The DT-DH switch or the PVI-800 task light status does matter outside of ROUTE mode with regards to being able to set your heading hold direction with the trim button.

 

The lesson: If you want to set your own heading hold direction while in autohover, you cannot be in DH or DT mode or you have to extinguish the active PVI-800 task light.

 

Yep thats kinda what I found.

 

As far as comparing the real deal to rc models, I fully agree, BUT the principle aerodynamics that are acting on it are the same but in a non linear scale, and basic cyclic and yaw maneuvers remain the same i.e. adding just cyclic in a hover state should not induce yaw. The point I was trying to make was that there seems to always be a some kind of heading hold in affect. If your near an airport, the heading somehow always lines up with runway even with a different waypoint tasked on the PVI. If you are away from an airport then the PVI current waypoint becomes the new heading hold even outside of route mode. This is just my own findings where I question if this is accurate in the real thing because personally I find it difficult to get my own headings locked in without some kind of AP interference and some of it doesnt make sense. How can you fly to a random airport and the runway heading becomes locked in the computer without changing frequency? I know I read in the manual that all the tower frequencies in the sim were the same to simplify the pilots need to not have to retune frequencies. Does this apply to ILS approach as well? What about when I just want to overfly the airport? Is there a way to make it so this magical ILS approach isnt always present?

[Frederf]

I think you're hallucinating. The Ka-50 doesn't magnet on to runways as far as the autopilot, PVI, or Route mode is concerned.

[Eldur]

Personally I don't hold trim during simply yaw-only autohover corrections. Why? Because when you hold trim button it disables all 3 channel holds and you start to float off the autohover mark in pitch and bank as well. In fact the trim button also resets the autohover position.

 

So what do you do then?

[bogusheadbox]

So what do you do then?

 

First thing i would do. ** Learn to hover without autohover **

 

Once you have that sorted, and want to rotate whilst in autohover. Whats wrong with "slew to target" command using the schval ?

[Frederf]

So what do you do then?

 

If I'm in an autohover state and I simply want to yaw without changing position or altitude then I simply put in rudder pedal and overpower the autopilot. Once I'm to my new heading I stabilize on that new direction for a second to make sure my pedal input is right and I tap the trim button.

 

If I were to press-n-hold the trim button during that yawing then I could easily drift away from my hover point and even build up some lateral or longitudinal velocity before I finished.

 

Turn-to-Target is nice for short yaw displacements but it requires that you have the Shkval out which may not be what you want to do at the time and the AP is not so good at compensating with rudder to not overshoot the mark and then wobble back and forth.

[Nate--IRL--]

What He said

 

I hope Kamov are taking note.

 

Nate

[bogusheadbox]

 

Turn-to-Target is nice for short yaw displacements but it requires that you have the Shkval out which may not be what you want to do at the time and the AP is not so good at compensating with rudder to not overshoot the mark and then wobble back and forth.

 

Why would you not want the schval out ? How on earth could it hamper?

 

There is no problem slewing arcs of 180 degrees or more and definitely no wobble. Hell its even far simpler using the HMS. The only time you would get a wobble is if you were not correctly trimmed out for autohover. ANd hence my first statement. Learn to hover without autohover and you will have very steady autohover from precise trimming.

 

Why on earth you would want to overpower/fight against the autopilot and then reset trim risking a control issue is beyond me, especially when the helo has a safe system to slew you accurately and, i bet, quicker --- Mindboggling:music_whistling:

Edited December 12, 2009 by bogusheadbox

[Frederf]

Perhaps you have a DL Ingress target queued up that you are going to going to use to hit a moving convoy so you have your weapon, ground moving target, etc queued up. So if you are using your Shkval to turn while hovering now you have unselect DL ingress, uncage, slew, turn to target, reset it and reprogram it before you uncage onto the DL memory point. That's a lot of faffing about!

 

There is most definately wobble with large AP yaws. It overshoots the heading and oscillates onto the heading. It also takes forever for the 20% control authority to execute the maneuver. Be aware that adding in manual rudder pedal does not fight the AP, that is a n00b myth. If the AP is using -1% authority in yaw to maintain heading it doesn't "soak up" +21% of pedal input by the pilot. It's simply additive and the AP doesn't try to maintain its overall state (just it's pre-pilot-input contribution) in the presence of pilot input.

 

If you want to yaw to a new heading while maintaining position and altitude the way I described is both the best and the most "real pilot" method.

[bogusheadbox]

Perhaps you have a DL Ingress target queued up that you are going to going to use to hit a moving convoy so you have your weapon, ground moving target, etc queued up. So if you are using your Shkval to turn while hovering now you have unselect DL ingress, uncage, slew, turn to target, reset it and reprogram it before you uncage onto the DL memory point. That's a lot of faffing about!

 

Wrong. .3 button clicks, to slew onto any designated target from any position i have already slewed onto, i give it about max 3 seconds to click away. Thats pretty safe and efficient in my point of view.

 

There is most definately wobble with large AP yaws. It overshoots the heading and oscillates onto the heading

With my method my schval is already slewed onto traget, any oscilation if any is within the bands of my main cannon firing solution and i already have a firing solution. sounds like you need to get things set up ready (once you have stabilised the helo). Not exaclty efficient in my view

It also takes forever for the 20% control authority to execute the maneuver

Well under what purpose do you want to alter heading in an autohover. I pressume its for scanning purposes. SLew to target gives a quick turn whilst enabling to scan the terrain you are sledwing through.

 

Be aware that adding in manual rudder pedal does not fight the AP, that is a n00b myth. If the AP is using -1% authority in yaw to maintain heading it doesn't "soak up" +21% of pedal input by the pilot. It's simply additive and the AP doesn't try to maintain its overall state (just it's pre-pilot-input contribution) in the presence of pilot input.

Let me get this straight. You say that the autopilot uses rudder input to maintain a stable hover and then say that manual rudder input does not fight against this. I beleive that is called a contradiction. However i must be wrong becase you said n00b (with two zero's for coolness - wow i wish i was 12 again). But i don't think so. If you are in a stable autohover and you yaw left and release pedels back to no input, does not the helo try to put you back at your original heading ???? That to me is fighting against autopilot.

 

If you want to yaw to a new heading while maintaining position and altitude the way I described is both the best and the most "real pilot" method.

 

Like i said. depends on what you want to do. For me, when i am stationary i like examine the area ahead in the direction i beleive i will travel for my firing position. I then slew using the schval to look and scan the areas to see if i will be comprimised on ingress and scan the areas where i would assume to be enemy contact. If i spot anything i have an instantaneous firing solution and ranging solution to either engage or mark any threats. 3 seconds later i am programmed to head onto my ingress heading with any threats found marked on my moving map.

 

however, if you want to spin around on the spot, and bumble blindly in the direction you wish to travel, then be my guest its your game.

 

If i was to do it your way. I would simply disengage the autohover manually rotate to the direction i wished to point and re-engage the autohover.

 

P.s. Real pilot method.... Are you a real pilot ? I don't fly anthing military and i don't fly helos, but i certainly know that the only time i overpower my autopilot is in the event of an emergency (trim runaway), but i always try to disconnect first.

 

Thats just the way i do it.

[Frederf]

Whatever.

[ARM505]

And, once again:

 

- Turn off heading channel.

 

- Point helo where you'd like it to go.

 

- Trim if needed.

 

The end. :)

 

P.S. Deal with Kamov rep complaining about doing naughty things with AP channels when you get home, receive Order of Lenin (or whatever they get nowdays), get movie/book deal for blowing up 3000 Abram's because you didn't end up being killed by your autopilot etc etc.

Edited December 13, 2009 by ARM505