how to land outside helipad?

[griffin12]

Hello,

About 50% of the times I try to land outside an helipad, on flat land, I crash. Everything looks good, I touch the ground about at 1m/s, but then, as soon as I'm on the ground, the helicopter starts to bend to the left, more and more until the rotor touch the ground and breaks.

 

What am I doing wrong? Is this a bug or something?

[1.JaVA_Platypus]

You should provide us with a track or a video. It makes looking at your performance a lot easier. Also, do you fly with the 1.5 open beta or the 1.2 stable version?

[griffin12]

Ok. Here you are, I've been trying it for a while and it happened on my last landing so you can fast forward to the last minute or so.

 

I managed to stabilize it at the last second but you can see there what happens to me all the time.

 

Im using DCS 1.5 but I see there is no bug, its my bad, I need some tip to land it, because seeing my tracks, I realize my landings are very bad.

 

Regards.

landings.trk

[Flamin_Squirrel]

You didn't do too badly, just need some tidying up.

 

Helicopters are complex beasts. In the hover, you need to apply pedal to oppose torque, which you probably realise, but this in itself brings other forces into play. It causes the helicopter to move (see translation tendency) opposite the direction of the applied pedal, requiring cyclic input to counter, which you've probably noticed too.

 

However, because the tail rotor is below the main rotor, the sideways forces are not in the same horizontal plane. This causes the helicopter to roll as well. This is why it's perfectly possible to be in a steady hover with the helo tilted to one side; this is quite pronounced in the DCS Mi-8. It looks strange, but you'll improve once you realise it's normal.

 

Now, avoiding tilting over or more formally: dynamic rollover. When landing, avoid any drift. You can make this easier by taking note of the wind. Like any aircraft you should land into it, but in the Mi-8 in particular you should avoid landing with a wind from the right (which I think is what you're doing in your track) as it will only make the drift/roll problem worse.

 

Avoiding dynamic rollover on takeoff is slightly easier; raise collective slowly and find the balance point with cyclic/pedals. If you feel yourself start to roll, lower the collective then try again. Don't raise it.

Edited November 1, 2015 by Flamin_Squirrel

[dooom]

i also cut throttle when i land and that helps immensely

[Flamin_Squirrel]

Very true, I forgot that.

 

Also, you'll find flying a gradual approach like an aeroplane helps. I've attached a track as an example.

example.trk

[griffin12]

Ok I see...

Is there no way to avoid that trembling at around 50km/h when braking? I usually panic there and raise collective to avoid VRS, so I get a lot of height and it breaks my plan.

 

I will keep practising the hover I thought the side movement was because some strange wind but now it makes sense, haha. Thanks

[Flamin_Squirrel]

You get that shuddering when you lose what's called transitional lift. It's not related to VRS (you avoid VRS by making sure you're not descending too fast when you lose transitional lift).

 

While you can't completely eliminate the shuddering as you slow, you can reduce it by decelerating less rapidly as you approach 50km/h.

[gospadin]

Ok I see...

Is there no way to avoid that trembling at around 50km/h when braking? I usually panic there and raise collective to avoid VRS, so I get a lot of height and it breaks my plan.

 

I will keep practising the hover I thought the side movement was because some strange wind but now it makes sense, haha. Thanks

 

With practice, you'll be able to raise collective to exactly counter the loss of translational lift, which will allow you to maintain your altitude. It takes a lot of practice to smooth it out, but once you get the hang of it it'll seem easy and natural.

 

VRS itself isn't scary, unless you have no recovery altitude remaining or terrain hazards would prevent a significant cyclic input to recover.

[1.JaVA_Platypus]

Every once in a while, I enter a VRS. Everybody does. You can escape from it by pushing the stick forward and raising the collective (not too high, RPM's will drop, generators will fail and the autopilot will cut off)

[gospadin]

Every once in a while, I enter a VRS. Everybody does. You can escape from it by pushing the stick forward and raising the collective (not too high, RPM's will drop, generators will fail and the autopilot will cut off)

 

Pushing the stick forward is good.

 

Whether or not to raise collective depends on where it was set when you tried to recover from the VRS.

[griffin12]

You get that shuddering when you lose what's called transitional lift. It's not related to VRS (you avoid VRS by making sure you're not descending too fast when you lose transitional lift).

 

While you can't completely eliminate the shuddering as you slow, you can reduce it by decelerating less rapidly as you approach 50km/h.

 

With practice, you'll be able to raise collective to exactly counter the loss of translational lift, which will allow you to maintain your altitude. It takes a lot of practice to smooth it out, but once you get the hang of it it'll seem easy and natural.

 

VRS itself isn't scary, unless you have no recovery altitude remaining or terrain hazards would prevent a significant cyclic input to recover.

 

Thanks guys, I'm doing much better knowing that. I just thought that vibrations = bad, so I tried to avoid them as a priority.

 

Every once in a while, I enter a VRS. Everybody does. You can escape from it by pushing the stick forward and raising the collective (not too high, RPM's will drop, generators will fail and the autopilot will cut off)

Yep, I don't crash that much on VRS (not anymore =D)

 

Now that you say, most of the times I take off with a heavy load my generators usually fail, whats the right technique to do it? When I'm on a mountain I just use ground effect to throw myself downhill, but it doesnt looks right, and anyway is not an option on flat ground.

 

Also I see there is two levers left of my collective for left and right engine throttle, but if I put them to maximum the only thing I achieve is make the generators fail earlier, but no significant power difference... What are they for?

[gospadin]

Thanks guys, I'm doing much better knowing that. I just thought that vibrations = bad, so I tried to avoid them as a priority.

 

 

Yep, I don't crash that much on VRS (not anymore =D)

 

Now that you say, most of the times I take off with a heavy load my generators usually fail, whats the right technique to do it? When I'm on a mountain I just use ground effect to throw myself downhill, but it doesnt looks right, and anyway is not an option on flat ground.

 

Also I see there is two levers left of my collective for left and right engine throttle, but if I put them to maximum the only thing I achieve is make the generators fail earlier, but no significant power difference... What are they for?

 

Per the manual, the engine governor cannot keep up with a change in rotor blade pitch of more than 3 degrees per second.

 

Ideally, you don't want to change it more than 1.5-2 degrees per second to give you some margin. This means pulling up much more gradually on the collective.

 

Similarly, dropping collective too fast will over-speed the rotor blades.

[Yurgon]

Now that you say, most of the times I take off with a heavy load my generators usually fail, whats the right technique to do it? When I'm on a mountain I just use ground effect to throw myself downhill, but it doesnt looks right, and anyway is not an option on flat ground.

 

The Russians had the same problem in Afghanistan, so they kind of pioneered the high-pitch rolling take-off where only the nose wheel remains on the ground until lift-off.

 

Fast forward to 5:59 minutes:

 

 

The entire 2-part documentation is highly recommended:

 

Mi-8 The Magnificent Eight (Film 1/2)

Mi-8 The Magnificent Eight (Film 2/2)

[gospadin]

Rolling takeoffs are awesome (and look great to observers)

[Slazi]

It's quite easy to take off with heavy payloads without rolling in the Mi-8. Just do it slowly and step by step. Unlock wheels, Apply a little collective. Adjust pedals and stick to hold you still. Trim. Apply. Adjust. Trim. Keep repeating and you'll be hovering nicely if weight allows. If you're a little to heavy, you need to add a little forward momentum.

 

If you're too heavy, then a rolling start will make things a lot easier.

[Looney]

Here I am, exactly the same problem with the shuddering at 50 km/h. I've been avoiding it like the plague since I thought it was the precursor to the VRS.

 

Although I can fly the MI-8, somewhat, I'm constantly dreading the descent-rate at slow speed (dead-mas curve) and still need to get to grasp on a good method of decelerating and descending without crashing.

 

The MI-8 does grow on me though, every time I fly it, I get better at it and it brings me more fun. In the beginning I danced the can-can for a long time as per Chucks MI-8 guide :P

 

How do you approach a landing zone where you have to land vertically, like a FARP?

[Flamin_Squirrel]

How do you approach a landing zone where you have to land vertically, like a FARP?

 

Unless you're landing in a small clearing amongst very tall trees, there aren't many situations where you have to make a true vertical descent. Most of the time you can still make an angled approach like a fixed wing aircraft, albeit the last bit might have to be steeper.

[griffin12]

Thanks guys, I learned more in this thread than in many weeks flying on my own. I'm starting to do better landings and take offs now

[Yurgon]

One thing I learned from reading books by helicopter pilots is that these guys are practically paranoid regarding engine failures.

 

Most decisions in helicopter flight must first and foremost make sure that the helicopter can be safely landed in case of engine failure.

 

Altitude (as with fixed wing aircraft) means safety.

 

Speed (as with fixed wing aircraft) means safety.

 

Thus, the most dangerous thing a pilot can do is enter a regime where neither are available.

 

Rescue choppers, those used for construction or lumber work, and of course military and police choppers that drop off troops on ropes, will be forced to fly in this regime. Every other pilot should avoid it like the plague.

 

A vertical descent landing puts helicopters right into that area where they would drop dead, so unless there are very good reasons to descent from OGE hover, a pilot should always keep up forward airspeed as long as possible, even if the final stage of the landing is just a small clearing like in the example given by Flamin Squirrel.

 

Once I realized this, my way of flying choppers in DCS changed quite a bit, even though only my virtual life depends on it. :thumbup:

[Slazi]

One thing I learned from reading books by helicopter pilots is that these guys are practically paranoid regarding engine failures.

 

Wise pilots.

Vertical descent isn't too bad in the Mi-8. You just have to be ultra careful. Get into a perfect hover. Turn on direction hold on SAS - one less thing to do. Then, very slowly descend. Aim for 0.5 - 1m/s rate. It may be slow, but its safer than rushing it.

 

Ideally, you want to be able to move forward in case of problems, but sometimes that isn't possible.

 

Doing this on a windy day is a different matter.

[vicx]

This is a different observation to the OP ... I find that once you get in the safe operating region inside the DCS sim then you can get away with a lot of silly things that you probably shouldn't be able to do.

 

I can land very roughly or bounce the helicopter very hard without penalty as a long as I keep the rotors out of harms way.

 

Can the suspension be damaged or broken? I haven't experienced that yet.

[Flamin_Squirrel]

This is a different observation to the OP ... I find that once you get in the safe operating region inside the DCS sim then you can get away with a lot of silly things that you probably shouldn't be able to do.

 

Depends what you mean by getting away with something. A heavy landing in DCS, just as it would in reality, may not result in any immediate/obvious damage. The difference is that minor damage in DCS won't result in a virtual mechanic coming to kick your arse, so you never notice.

[gospadin]

This is a different observation to the OP ... I find that once you get in the safe operating region inside the DCS sim then you can get away with a lot of silly things that you probably shouldn't be able to do.

 

I can land very roughly or bounce the helicopter very hard without penalty as a long as I keep the rotors out of harms way.

 

Can the suspension be damaged or broken? I haven't experienced that yet.

 

Yes, you can break the skids off of a Huey. You can also break the landing gear on the Mi-8, however, the force required to do so exceeds the force required to break the tail boom, so you'll typically break your tail boom first.

 

When I fly helicopters, whether this is a good practice or not, I typically land in this order:

 

1. I descend before losing my airspeed. I try to keep my velocity above 100km/h to maintain transitional lift, which allows me to descend at a rate significantly faster than 3m/s with low risk.

2. Approaching my landing area, I level out, which reduces vertical velocity to 0.

3. I then pull back on the cyclic and reduce collective, to cut my horizontal velocity, with an increase in collective as I lose translational lift.

4. I then do my final descent of the last 30m or so as needed, as carefully as possible.

[Flamin_Squirrel]

That's not good practice tbh. You leave youself vulnerable to crashing if your engine(s) fail.

 

Your approach should be at a constant angle, liked a fixed wing aircraft (albeit steeper). At an appropriate point in your approach, start to bleed off speed, which should also be constantly reduced, aiming to reach 0m and 0km/h at the same time.