need track replay Apache falls from the sky like a ton of bricks...

[AndreNL]

    Dear pilots, 

Me and my buddy have been flying the AH64 since its launch. We have experienced all kinds of things with the updates, both positive and negative, and in the end we have seen the module grow positively into something beautiful. 

Now we both often experience losing our grip out of nowhere and falling like a stone from the sky. This usually happens when we approach an airport and slow down to land quietly. 
Or when we circle around an AO where our speed is around 40 knots. 

Could this be a desync problem, or is there something wrong with the flight model? 

Before I start making videos again, I would like to ask if more pilots experience this. 
I also fly the KA-50III where I can't even create this problem. 

Thank you in advance!

[Oldahpilot]

It certainly is very sensitive to low airspeed and rates of descent of more than 300 fpm. Battle positions down wind are particularly challenging when heavy, I'm planning escape routes all the time, leaving enough clearance to get the nose down and turn into wind to gain airspeed at any time.

When approaching to land I use a very deliberate combination of gradual reduction of speed and height, or a quick stop into wind at a shallow angle of approach. Whichever method i use i'm always aware of the wind. This is more of a truck than a sports car.

[[DE] T-Bone]

I haven't had anything like that myself before. Does it happen more in the transition to a hover. Does it happen also above 40 knots?

Edited June 13, 2024 by [DE] T-Bone

[AndreNL]

@[DE] T-Bone

 

    We have flown together many times and we notice that we both experience this. But it does happen during slower flying around 40 knots. It's not that we don't have experience with the ah64, we have been flying since the rollout of the ah64. We wonder if the flying model is realistic, we think something is wrong... 
I will try to film it...

[Floyd1212]

It's hard to say if this is just VRS, or if something else is going on.  Can you fly an Instant Action mission and do a couple landings and see if you can capture it with a track file?

[LuseKofte]

Have you switched from Caucasus to Syria 

I am not sure how much temperature is a factor in this simulation. According to interviews I seen we can load the choppers more than they did in rl in hot temperatures. 
Anyway it is a difference in lift between hot and cold weather in this sim. And you will notice it close to the choppers envelope. 
My impression is that most sim pilots are hesitant to take less ordinance and expect the chopper to perform as they do in normal temperature

[T.Power]

I'll throw my two cents in as someone who recently upgraded from a X52 to a full Winwing setup with pedals.  I own all the rotor modules aside from the Kiowa, I mostly fly the Hind which has it's own quirks and nuances, but I fly them all periodically to remind myself of the differences.  The Apache is a very odd machine, as someone else pointed out it's a truck not a sportscar, and I really do feel that the Apache suffers from feeling like it's actually a sportscar to the point I used to have my axes with saturation set at 20 and I used the trimmer all the sodding time.  Desaturating the Joy axes really helped me learn to fly it like a truck, then I used autopilot modes to help transition and landing, because when VRS sets in with the Apache, it appears nigh on impossible to stop it.  Rotors really do benefit from longer sticks with dampers and soft springs.

[[DE] T-Bone]

54 minutes ago, AndreNL said:

@[DE] T-Bone

 

    We have flown together many times and we notice that we both experience this. But it does happen during slower flying around 40 knots. It's not that we don't have experience with the ah64, we have been flying since the rollout of the ah64. We wonder if the flying model is realistic, we think something is wrong... 
I will try to film it...

Same here, I fly it almost every day and have never seen this effect before, not even after the patch...

Yes, a video or a track file would be perfect to take a look at the phenomenon. 

[Homelander]

 vor 5 Stunden schrieb LuseKofte:

Have you switched from Caucasus to Syria 

I am not sure how much temperature is a factor in this simulation. According to interviews I seen we can load the choppers more than they did in rl in hot temperatures. 
Anyway it is a difference in lift between hot and cold weather in this sim. And you will notice it close to the choppers envelope. 
My impression is that most sim pilots are hesitant to take less ordinance and expect the chopper to perform as they do in normal temperature

The temperature has a very large influence on the AH-64D in DCS. Setting the temperature to 50°C causes the Apache to crash like a wet sack.
Is this intentional? I don't know.

@BIGNEWY
Do you know more about this?

[Floyd1212]

I'm not sure we need BIGNEWY in here to tell us that helos do not operate well in extreme heat or at high altitudes.

[LuseKofte]

24 minutes ago, Homelander said:

Setting the temperature to 50°C causes the Apache to crash like a wet sack

Altitude and heat should have that effect. I tried to hoover Hind in heat and altitude. And it should not do that with full load. 

[Tholozor]

If the outside air temperature is greater than 24°C, the intermediate gearbox can overheat if hovering out of ground effect for extended periods of time.

[Homelander]

I'm not really familiar with the flight characteristics of helicopters. But what I don't understand is that George can't keep an Apache hovering at 50°C without armament. However, with a Ka-50, this poses no problem, even when fully armed.

Here is a trackfile.

helo temp.trk

[Floyd1212]

2 hours ago, Homelander said:

But what I don't understand is that George can't keep an Apache hovering at 50°C without armament.

Ah, you didn't mention George in your previous statement.  You may just have a "George" problem.  There are reported issues with George not being able to hold a hover in situations where a human pilot can.  You may be better off commenting in one of those threads; the OP in this current thread was talking about losing the aircraft when coming in to land with a human pilot.

Maybe try this one:

https://forum.dcs.world/topic/350096-george-hovering-skills/

 

2 hours ago, Homelander said:

However, with a Ka-50, this poses no problem, even when fully armed.

Yes, but the Ka-50 has twice as many rotors, yes?

I'm half kidding, but the point is that the two aircraft are hard to compare because of their very different rotor designs.

Edited June 14, 2024 by Floyd1212

[Homelander]

@Floyd1212
The Apache sinks right at the start of the mission. The airspeed is set to 0. Take a look at the track.

PS: If the Apache is armed, then even as a pilot I can't keep it in the air at all.

Edited June 14, 2024 by Homelander

[Floyd1212]

1 hour ago, Homelander said:

The Apache sinks right at the start of the mission. The airspeed is set to 0. Take a look at the track.

This appears to be a George issue.

The PERF page says you will require 91% torque to maintain an OGE hover in the current conditions and weight.  George seems to only want to pull 87%.

Edit: Forgot to insert my screenshot.

Edited June 14, 2024 by Floyd1212

[JetCat]

On 6/13/2024 at 11:40 AM, AndreNL said:

Now we both often experience losing our grip out of nowhere and falling like a stone from the sky. This usually happens when we approach an airport and slow down to land quietly. 

This can happen when the variomater indicator crawls down to more than -500 feet per minute when the Apache goes below 10 knots of air speed. The variometer begins to go down very fast the slower the Apache gets because oncoming air enhances the uplift, and slowing down rapidly takes away this uplift. In this case it´s the vortex ring state, and it falls vertically down with the cockpit frame shaking. In this case you must pull the stick forward to gain forward momentum, at 15 to 25 knots you will go out of the VRS. Coordinating the loss of uplift while slowing it down without getting into vortex ring state is rather difficult.

The second quirk it sometimes does is suddenly pulling the nose up very radically (20° or even 30° of pitch) while slowing down, combined with falling out of the sky while slowly flying backwards. I think there is some rear rotor disk stall simulated, but I don´t know enough about helicopters (yet) to confirm that, or to know how to provoke rotor stalls.

Yes having it fall out of the sky like a brick is possible, which makes flying it even more exciting

[mcfleck]

I'm not really familiar with the flight characteristics of helicopters. But what I don't understand is that George can't keep an Apache hovering at 50°C without armament. However, with a Ka-50, this poses no problem, even when fully armed.
Here is a trackfile.
helo temp.trk

Dude, 50°C...
I don't know the operational OAT limits for the Apache, but the helicopter types I flew (military and civil) were/are all limited to ISA +35°C.

With ISA being 15 degrees at sea level, 50°C is an extreme stress for the aircraft and all its parts.
You cannot expect being able to hover in such conditions.

Have you looked into your engines page? What is the limiting factor? In hot/high conditions it is not necessarily your torque. Your engines might run out of power (T4/TOT or N1/Ng being the limiting factor) before your gearbox reaches its torque limit.

Btw: Sorry, but I have not looked into your track file, as I won't have my PC available for the next couple of days.

[[DE] T-Bone]

@AndreNL

I tried to recreate the problem for over an hour yesterday without success, the helicopter didn't show any sudden descent or anything like that.

Were you able to reproduce it again?

[Yurgon]

On 6/13/2024 at 11:40 AM, AndreNL said:

Now we both often experience losing our grip out of nowhere and falling like a stone from the sky. This usually happens when we approach an airport and slow down to land quietly. 
Or when we circle around an AO where our speed is around 40 knots. 

Track or it didn't happen.

This certainly sounds like Vortex Ring State, i.e. the helicopter falling in its own rotor downwash, but at 40 knots forward speed VRS shouldn't set in.

I've read over and over from real life helicopter pilots that VRS is over-modelled in DCS. But at least I'm not aware of any significant flight model changes to the Apache in this regard.

Since variables like air temperature and altitude aka density altitude were already entered into the discussion, it's not much use trying to remote-debug such issues. We need to see it happen first hand. A short track would be preferable, and barring that, a video that starts at least 10 seconds before the onset of the problem would be good.

Edited June 17, 2024 by Yurgon

[AndreNL]

6 minutes ago, Yurgon said:

Track or it didn't happen.

This certainly sounds like Vortex Ring State, i.e. the helicopter falling in its own rotor downwash, but at 40 knots forward speed VRS shouldn't set in.

I've read over and over from real life helicopter pilots that VRS is over-modelled in DCS. But at least I'm not aware of any significant flight model changes to the Apache in this regard.

Since variables like air temperature and altitude aka density altitude were already entered into the discussion, it's not much use trying to remote-debug such issues. We need to see it happen first hand. A short track would be preferable, and barring that, a video that starts at least 10 seconds before the onset of the problem would be good.

 

I'm gonna make a video. But at the moment very bussy at work

Edited June 17, 2024 by AndreNL