Auto hover problems

[achoice]

Hello, I've experienced some problems regarding auto hover.

Several times I've engaged auto hover only to find that I loose control - chopper spins etc. When I glance at the blue auto-pilot buttons 3 of them are flashing!

My interpretation of what happens is this;

I fly fast... The three normal AP-dampers engaget

I spot a target, lock it, engage "Auto turn to target"

I manually try to hover chopper.

I engage "auto hover". (perhaps a bit to early...)

Whoops - I loose control. Chooper spins and is very hard to control!

 

It seems as auto-hover has disabled the three AP-dampers. Looking at the blue buttons they are now flashing! I disable Auto hover and manually click the three dampers again - phew. I've had several crashes due to this.

 

I wonder - what causes the three AP-dampers to flash/disengage?

 

Follow up question: Some times the texture on the blue AP-damper-buttons change. The brightness changes so that it is hard to tell if they are enabled or disabled. Anyone experienced this?

 

regards David, Sweden.

[sobek]

Hello, I've experienced some problems regarding auto hover.

Several times I've engaged auto hover only to find that I loose control - chopper spins etc. When I glance at the blue auto-pilot buttons 3 of them are flashing!

My interpretation of what happens is this;

I fly fast... The three normal AP-dampers engaget

I spot a target, lock it, engage "Auto turn to target"

I manually try to hover chopper.

I engage "auto hover". (perhaps a bit to early...)

Whoops - I loose control. Chooper spins and is very hard to control!

 

It seems as auto-hover has disabled the three AP-dampers. Looking at the blue buttons they are now flashing! I disable Auto hover and manually click the three dampers again - phew. I've had several crashes due to this.

 

Is any of these true?

 

[ ] you engaged the autohover below 4 m AGL

[ ] you did not trim for a hover before you engaged AH

[ ] you pulled so much collective on entering the hover, that the funny beeping noise sounded and the zebra light flashed

 

Please elaborate :)

[achoice]

Is any of these true?

 

[ ] you engaged the autohover below 4 m AGL

[ ] you did not trim for a hover before you engaged AH

[ ] you pulled so much collective on entering the hover, that the funny beeping noise sounded and the zebra light flashed

 

Please elaborate :)

 

a) Every time was way above 4 AGL.

b) I trimmed. but perhaps I was 1) not quite in hover-mode when activateing auto-hover 2) engaged Auto Hover "while trimming"..?

c) Hmm. No dont think so.

 

Any how - I wonder what causes the AP-dampers to disengage and flash when I'm way above 4 AGL. I'm learning to take more care with auto hover - but still - I find quite dangerous.

[159th_Viper]

At what speed do you engage AH? Advisable to do so at 0-5 km/h IAS.

[VMFA117_Poko]

^ Yeah, better to engage autohover when you're already in hover.

[achoice]

At what speed do you engage AH? Advisable to do so at 0-5 km/h IAS.

 

Yes I know - it might well have been above 5 km/h IAS. I understand I should engage below 5. But I find it puzzling and dangerous that AP-dampers are flashing/disabled without warning if I engage when flying to fast.

 

Perhaps it's part of simulating an unforgiving reality? :)

 

regards David.

[sobek]

a) Every time was way above 4 AGL.

b) I trimmed. but perhaps I was 1) not quite in hover-mode when activateing auto-hover 2) engaged Auto Hover "while trimming"..?

c) Hmm. No dont think so.

 

Any how - I wonder what causes the AP-dampers to disengage and flash when I'm way above 4 AGL. I'm learning to take more care with auto hover - but still - I find quite dangerous.

 

b) You need to be properly trimmed for a hover for the autopilot to be able to hold you steady. Remember, the AP has only 20% authority. If you trim past 20% of the stick position necessery for the hover, what's the AP supposed to do? Right, go haywire :). Press right ctrl+enter when you're in the hover and make sure all your control surfaces are not trimmed way out of line, then and ONLY THEN will you engage the auto hover :)

 

c) Think again ;) But seriously, this slips past a lot of newcomers. Try to pay close attention. If the heli starts to beep, that means your rotor RPM is low, which causes your generators to go on vacation and that means the INS gyros get all depressed because the generators are just really nice fellows to trade some current with. :) The AP, in turn, needs the INS to tell him what the heck he is doing but instead its just lying in the corner being depressed so he says: f*** me, i'm outa here, you looneys fly that thing alone.

 

This and being below 4m AGL are the only reasons known to man (that's me, i'm the man ;)) causing the AP to shut off. At least these are the ones that i caused when i started to fly.

 

god i need some sleep :music_whistling:

 

edit: btw. i'm usually not that goofy, it's just to celebrate the 10000th time somebody explained this on the forum, so maybe next time, try the search button, it won't bite you :thumbup:

Edited September 2, 2009 by sobek

[EinsteinEP]

Another cause of auto-hover madness is if you engage auto hover before doppler nav system is up. Check the upper left of the hud. No ground speed = no doppler nav. (BTW, this is one of the reasons why low rotor rpm knocks out the auto-hover too. Low rpm = generators disengage = doppler nav goes sleepy time).

[Martillo1]

If the heli starts to beep, that means your rotor RPM is low, which causes your generators to go on vacation and that means the INS gyros get all depressed because the generators are just really nice fellows to trade some current with. :) The AP, in turn, needs the INS to tell him what the heck he is doing but instead its just lying in the corner being depressed so he says: f*** me, i'm outa here, you looneys fly that thing alone.

 

I tought the INS was well served with batteries power (either DC or AC through the inverter). Is it not that way?

[sobek]

I tought the INS was well served with batteries power (either DC or AC through the inverter). Is it not that way?

 

 

Uh, ya i think you're right, IIRC it's the doppler nav that ceases to work, either way, AFAIK the doppler nav is linked to the INS which is in turn linked to the AP. The result is the same.

[Slayer]

Lighten up on the stick a bit and try to work the controls smoothly this will go a long way. If you ever fly in the mountains at high altitude you will quickly see how heavy handed flying impacts the helicopter.

 

Any easy trick to keep engine power up is to turn off the dust/ice protection if you don't need them...They rob engine power.

 

You can also bump up the engine throttles to emergency power and this seems to help a bit if your heavily loaded and manouvering hard. Some purists get mad about this one but who cares...it's modeled and pretty much any mission you fly will be over before the engines start to degrade..

[Celo63]

I am quite surprised that you need to trim the aircraft perfectly before the autohover can safely keep you in one spot. After all, the trim system is directly linked to the autopilot. Why can't it trim itself out if you aren't quite spot on when you engage hover mode? It should be able to handle that easily despite using only 20% controls. Surely it can trim itself out and maintain the hover in most conditions???

 

Russian helicopters have long been famous for their advanced autopilot systems and Kamov was one of the foremost pioneers. Look at this article on the Kamov KA-32. Look to the right under "Facts and Figures, 3rd one down...

 

http://www.aviastar.org/helicopters_eng/ka-32.php

 

Quote "When flown by a single crewmember the Ka-32 can be left on autopilot while the pilot operates a winch from the cabin."

 

You'd need alot of confidence in your autopilot to leave the seat and go play winchman in the rear. I bet their hover mode doesn't start going wild on them while they're winching in a survivor - and in pretty severe weather too.

 

In the sim, the KA-50 seems to need constant babysitting, even in very light wind conditions. Surely the real KA-50 has a more robust and confidence inspiring autopilot and autohover system?

[Shepski]

If your altitude is too high for the current weight of the Ka-50 to hover when you try to auto-hover it will disengage the stability channels.

[ruprecht]

Using simplified flight model buggers up autohover. Sounds weird, but that's my experience in a mission that "forced" simplified FM. It was all over the shop as you describe.

 

Make sure Flight Director is off if you're using autopilot/autohover.

[scatter]

I found early on that my survival rate increased dramatically after I removed "autohover" from my HOTAS.

 

In the sim it's not worth it in my opinion as I need to be pretty much hovering first, and then if any of its "disengage" parameters occur it actually switches stabilisation off which is suicidal.

 

Hovering manually is pretty easy - in V1.0 I trimmed my cyclic slightly forward after take off to maintain a hover, and then tried not to touch it again. From then on when I release the cyclic the aircraft would go to something resembling a hover (depending upon wind). In V1.01 it seems to be a bit more difficult but I'd still avoid autohover like the plague.

[GGTharos]

Surely it can trim itself out and maintain the hover in most conditions???

 

It surely can, but a lot of people can't use it very well it seems.

 

Russian helicopters have long been famous for their advanced autopilot systems and Kamov was one of the foremost pioneers. Look at this article on the Kamov KA-32. Look to the right under "Facts and Figures, 3rd one down...

 

There's nothing advanced about them.

 

You'd need alot of confidence in your autopilot to leave the seat and go play winchman in the rear. I bet their hover mode doesn't start going wild on them while they're winching in a survivor - and in pretty severe weather too.

 

I bet they never go out single-handed and have the pilot leave his seat to perform such an operation. The possibility exists, but reality dictates that doing such things is a good way to die.

 

In the sim, the KA-50 seems to need constant babysitting, even in very light wind conditions. Surely the real KA-50 has a more robust and confidence inspiring autopilot and autohover system?

 

All aircraft need babysitting. That's why you don't see airliners literally flying themselves.

[159th_Falcon]

All aircraft need babysitting. That's why you don't see airliners literally flying themselves.

 

Actually the reason is something else. If passengers of an airplane would know there actually is no pilot onboard they will refuse to get in.

Technically its perfectly possible for an aircraft to start up, taxi, take-off, follow an route, land, taxi and shut down. All whitout any interference from an human pilot.

(actually on some airlines it already happens, yet the pilots are still there to monitor everything.)

[astrospud]

...Technically its perfectly possible for an aircraft to start up, taxi, take-off, follow an route, land, taxi and shut down. All whitout any interference from an human pilot.

(actually on some airlines it already happens, yet the pilots are still there to monitor everything.)

 

AFAIK, modern UAV's can perform auto return and land after losing links with ground operators.

I am not 100% certain, but I think Global Hawk is a truly pilotless UAV, i.e. "autopilot", performing entire sorties autonomously.

 

Achoice, with regard to your original question, I believe I have experienced something similar to what you describe. I pinpointed the problem for my experience to my bird entering VRS (vortex ring state), as I flared too aggressively, and with too much collective to pull it up in a short distance from a high forward velocity. Just a guess, but it sounds familiar.

[ruprecht]

(actually on some airlines it already happens, yet the pilots are still there to monitor everything.)

 

In modern airliners the pilots are there for 3 reasons:

 

- passenger confidence

- emergencies

- sequencing with ATC

 

They are not technically required to pilot the aircraft from A to B, but airspace is dynamic and the existing ATC systems are not advanced enough to manage fleets of autonomous aircraft mixing it up with bugsmashers, thunderstorms and plain old idiots.

[Celo63]

It surely can, but a lot of people can't use it very well it seems.

 

There's nothing advanced about them.

 

I bet they never go out single-handed and have the pilot leave his seat to perform such an operation. The possibility exists, but reality dictates that doing such things is a good way to die.

 

All aircraft need babysitting. That's why you don't see airliners literally flying themselves.

 

1) It only works well when already trimmed for hover - which is how its supposed to be used of course. All I was saying is that it doesn't cope well with the aircraft being a bit out of hover trim. It will tend to drift easily unless you trim very well before engaging hover mode. Or so I have found.

 

2) Maybe compared to modern technologies they don't seem advanced but back in the days when Kamov was pioneering them, they were considered cutting edge. They were more advanced than most western systems of the time.

 

3) They would avoid single pilot operation if possible I'm sure. Its wise to have a 2 man crew. However, I'm sure they have been used single pilot on at least a few occasions and have performed very well. It was designed specifically for that and they would have tested and proven the system. Does what it says on the tin.

 

4) As others have said, systems are advanced enough today that pilots are no longer 100% neccessary, but rather are desirable to have onboard for various reasons.

 

I do agree that the KA-50 system works well as long as you trim properly beforehand - which is how its supposed to be done. I just thought that it could cope with "out of trim" situations a bit better. Unless properly trimmed beforehand, the KA-50 will most likely start to drift in hover mode.