Mi-24P flight characteristics

[manielebo]

The Hind is an enigma to me. I feel like I have a pretty good handle on helicopters and helicopter flight. Very proficient in the Huey and Hip. Passable with Apache. But for whatever reason the Hind perplexes me. I find myself constantly battling when coming into a landing, between the lack of visibility and the propensity for the Hind to enter VRS, anything other than a very long slow approach is instant death.

Also, uncertain if it’s a bug, or intentional, when making a turn in the hind, pulling aft cyclic, if the airspeed drops below ~150kph the nose pitches up violently and performs a “hockey stop”.  https://19216811.cam/ Is this intentional? How do I avoid this?

I guess my question is, what am I missing? What am I doing wrong? Is the Hind just that much of a handful? Is this just a get gud idiot type of thing? Or am I just missing something?

Edited October 31, 2023 by manielebo

[AeriaGloria]

1 hour ago, manielebo said:

The Hind is an enigma to me. I feel like I have a pretty good handle on helicopters and helicopter flight. Very proficient in the Huey and Hip. Passable with Apache. But for whatever reason the Hind perplexes me. I find myself constantly battling when coming into a landing, between the lack of visibility and the propensity for the Hind to enter VRS, anything other than a very long slow approach is instant death.

Also, uncertain if it’s a bug, or intentional, when making a turn in the hind, pulling aft cyclic, if the airspeed drops below ~150kph the nose pitches up violently and performs a “hockey stop”. Is this intentional? How do I avoid this?

I guess my question is, what am I missing? What am I doing wrong? Is the Hind just that much of a handful? Is this just a get gud idiot type of thing? Or am I just missing something?

I don’t know what you mean about 160 kmh, but from 200 kmh to max speed there is a pitch up behavior called “Podkhvaht (pick up in Russian).” 
 

If you exceed the G limits set in the manual, it basically causes an aggressive mush/rotor stall that requires you to move cyclic forward and reduce collective 1-3 degrees to recover

 

It is described in many army manuals, but you can get the gist of it from this video 

 

 

It basically happens when teaching 0 AOA or positive AOA at high speeds, which causes up flow through the rotor disk and thus causes a rotor stall. 

Coincidentally, to Create maximum lift the wings are installed at a 19 degree angle, and stall at around the same angle. So when you hit this 0-positive AOA region, the wing also stalls. 
 

If you notice, the wing isn’t directly below the rotor, but behind it. This means that as it creates lift, it also creates a nose down force that helps you need less forward cyclic in forward flight. 

But when that wing stalls, the nose down force it was creating mostly goes away, increasing the pitch up tendency of the now stalling rotor 

The manual places a heavy speed restriction on this, the faster you are the more you should limit G. In my experience in DCS the speed you are doesn’t effect the G that this effect happens, but does increase how sever it is and how much effort it takes to recover 

At low weights and altitudes this is around 1.8 G. If extremely lightweight and near sea level 2 G is the absolutely maximum you could ever pull without this “cobra” effect happening 

As you go to 1000m, you might be limited to 1.6 G, and once you are at 2,000m or above more like 1.4 G. 
 

If you are fully loaded (11,500 kg), even being low to the ground you are often limited to 1.6 G just out of weight. 
 

It has been tuned recently and is less aggressive, but still happens around these G levels. 
 

While the normal reaction is cyclic forward, and you do need that, reducing collective has the greatest effect as it increases the angle the rotors can be without stalling. You will often notice just a 1-3 degree decrease in collective will snap the nose back down. 
 

As a preventative, you can even reduce collective beforehand. At max collective it is worst, 12-14 degrees is good middle ground, and below 10-11 degrees the effect starts to stop being sudden and basically goes away unless you force it. 
 

So keep an eye on G meter and collective pitch, You will hear the blades start to flap as this occurs 

It is good to be conscious that wether you are in a fixed wing or rotary wing, in a level turn your G has a direct relation with bank angle. If we consider 2 G the limit, this means that at low altitude and weight your absolute bank angle limit in a level turn is 60 degrees. At more medium weights and low altitude, for a 1.8 G limit, you are closer to 55 degree bank angle limit. 
 

At higher altitudes and weights, where you are limited to 1.4-1.6 G, you may only be able to bank 45-50 degree in a level turn. It is for this reason there is a 45 degree bank angle limit in the manual for peacetime and the aerodynamics section warns that any level turn with bank angle above 45 degrees begins to become unsteady and hard to perform. 

I hope that helps, cheers 

 

[martin.kloubek]

I saw a video of a Czech pilot with Mi24, he said that you have to fly this machine like a plane. Since then, i change my atitude with Mi24 and i stoped faling down. RN after 1 year of flying Mi24, for me its most stable and controlable helicopter from all in DCS. Its not a fighter, its more like flyng tank. Fully loaded its like 8 tons compare to Ah64 Apache with 5 tons. All those quick reactions will lead to a crash. For safe landing, you need always movement, even minimal but still movement. Sure you can land from hoover but it take a lot of practice

[Gunnar81]

58 minutes ago, martin.kloubek said:

I saw a video of a Czech pilot with Mi24, he said that you have to fly this machine like a plane. Since then, i change my atitude with Mi24 and i stoped faling down. RN after 1 year of flying Mi24, for me its most stable and controlable helicopter from all in DCS. Its not a fighter, its more like flyng tank. Fully loaded its like 8 tons compare to Ah64 Apache with 5 tons. All those quick reactions will lead to a crash. For safe landing, you need always movement, even minimal but still movement. Sure you can land from hoover but it take a lot of practice

Agreed 100%. I went from flying the Apache a lot and back to the Hind after 6 or more months and I rolled it over to pull a tight turn and it pitched up and bled airspeed so fast I almost dropped out of the sky. Totally my fault. But yes if you treat it more like a plane with big deliberate movements it feels really stable.

Edited November 3, 2023 by Gunnar81

[LuseKofte]

I can land it just as I land a hip. A heavy hip. You need to always look at your descent rate and if you go below 5 too fast you ain’t going to make it. You cannot expect pulling the collective in a hurry to help you

[Sobakopes]

To overcome lack of visibility you land sideways going diagonally. Heading hold is useful for takeoff landing and hover

[Brigg]

On 10/30/2023 at 11:15 AM, manielebo said:

The Hind is an enigma to me. I feel like I have a pretty good handle on helicopters and helicopter flight. Very proficient in the Huey and Hip. Passable with Apache. But for whatever reason the Hind perplexes me. I find myself constantly battling when coming into a landing, between the lack of visibility and the propensity for the Hind to enter VRS, anything other than a very long slow approach is instant death.

Also, uncertain if it’s a bug, or intentional, when making a turn in the hind, pulling aft cyclic, if the airspeed drops below ~150kph the nose pitches up violently and performs a “hockey stop”.  https://19216811.cam/ Is this intentional? How do I avoid this?

I guess my question is, what am I missing? What am I doing wrong? Is the Hind just that much of a handful? Is this just a get gud idiot type of thing? Or am I just missing something?

 

That's interesting, I'm a Jug main normally but being playing the whirly birds lately and find the Hind by far the easiest to fly. I suppose we all have a different feeling of what feels natural 

[AeriaGloria]

5 hours ago, Sobakopes said:

To overcome lack of visibility you land sideways going diagonally. Heading hold is useful for takeoff landing and hover

Or you could approach with forward motion as normal, while looking out the left hand side