Mi-8 - not flying straight and vibration

[RabidRider]

A couple of weeks ago I bought the Mi-8 module, my first helicopter. So far, I've only flown the freeflight mission a few times and yesterday I tried taking off in the virtual aerobics server. I used the autostart sequence (haven't gotten to studying this yet:)) and after my second attempt, I took off succesfully.

 

I have the CH fighterstick and throttle, but no seperate rudder yet. I use the microstick on the throttle for that.

 

In the freeflight mission I can keep Mi-8 up in the air without any real problems. Only thing is that sometimes it starts to fly forward at an angle, so not straight forward. Applying rudder with the microstick does not really seem to help. Any advice on how to counter this?

 

Trying to land in the freeflght mission, the Mi-8 also seems to want to start flying at an angle or sideways. Cyclic or rudder does not seem to counter this. I must be doing something wrong.

 

I do use the trim, and that works, but not for the sideways drift or the angle at which the heli seems to want to fly.

 

 

In the multiplayer session, I managed to take-off and get a more or less stable flight initially, pretty soon however, the Mi-8 started vibrating. Collective was at almost full power I think. Why is this? Reducing collective didn't seem to help. Somehow vibration stopped after a while, then after a while recommenced. The angled orientation while flying forward was also more pronounced than in the freeflight mission. Trying to correct, adjusting collective, resetting trim, after a while I crashed. Instability was never this pronounced in the freeflight mission, very strange.

 

So, any ideas on what i'm doing wrong, how to just fly as stable and smooth as possible, or is this impossible without a seperate rudder?

[Art-J]

Difficult to say without You providing some recorded tracks for reference.

 

Do You use the heading channel of the autopilot? In high load/torque situations it changes the rudder position to maintain the heading but doesn't change it back when load gets lower and the heli starts flying with a constant sideslip until You use the trim reset button to straighten the rudder out. Actually You have to use trim reset as often as the trim engage function.

 

Heading autopilot or not, this chopper requires lots of smooth and precise rudder input in many situations. Microstick might not cut it. Something with longer throw should make flying much easier, not even expensive rudder pedals - I use a set from a racing wheel, they're not perfect, but they do the job just fine.

 

Vibrations at full power and high pitch-down orientation suggest You might be flying just too fast and hitting the retreating blade stall zone, but without a track it's just a guess.

 

Did You read the draft of English manual for the "Hip" posted somewhere here on the forum a couple of months ago? It has lots of good advice about flying this crate.

[RabidRider]

Yes I might have been flying too fast. Almost max collective and nose down.

 

Thanks for the info on the autopilot heading channel. Yes, I need to start resetting the trim more often, only reset it once during that short flight.

 

I guess I thought that flying this heli would be a bit easier :)

 

Will start saving up for a rudder too.

[Socket7]

Beyond 250 kph, you'll start noticing a marked tendency for the MI-8 to want to pitch down and roll. It is accompanied with vibrations. The solution is to slow down. :)

 

Stay below 250kph and you should be fine. In icing conditions however, you may find the vibrations persist all the way down to around 190 kph.

 

The only time I use the heading autopilot is when I'm going to be traveling in a straight line for a long period of time, and want to be able to take my feet off the pedals. Continuous maneuvering with it enabled causes the pedals to end up trimmed in bad ways that require a trim reset. Since you're using a ministick for your pedals, it could be a handy tool, if you bind buttons to adjust it manually, and are liberal with trim reset.

 

Flying a helicopter without pedals is a very tall order. Keeping the helicopter facing the way you want requires fine adjustment of the anti-torque pedals in response to other control inputs. It's not impossible, but some real pedals will help a lot, because you are adjusting them constantly.

 

I have a tutorial video on the doppler navigation system. It includes a meter that helps you hover, and a meter that helps you tell if your helicopter is crabbing to the left or right when moving forward. Could be useful info for some of your troubles.

 

Be patient! It's a very rewarding aircraft to fly once you get the hang of it!

Edited May 2, 2015 by Socket7

[RabidRider]

Thanks for the info and advice Socket7, will watch your tutorial!

[EagleFox]

VNE for mi8 is 250km/h so stay below that, also when flying on high altitudes that VNE falls down also in cold conditions. Keep that in mind. As I recall at the 1000m the VNE falls 100km/h maybe little less but its somewhere near that.