Autorotation in UH-1H

[fixen]

Hello Huey pilots

 

Let me start by telling you that I am a noob huey pilot so I might have some things wrong.

I would like to know how you guys autorotate in DCS, but first let me tell you what I do:

 

Once I notice that the engine RPM is going down I drop the collective. I will try to keep the helicopter in a low angle dive and steer it to a good location for landing. When close to the ground I flare and pull the collective.

 

But what happens in DCS. The moment engine RPM is going down and I drop the collective, I drop like a brick. Cyclic inputs do nothing and rotor RPM keeps going down. When I increase the collective a bit the rotor rpm goes up a bit, but not enough and I still drop like a brick. If I increase the collective even more the rotor RPM drops again and I fall like a brick.

 

I thought that the whole idea behind autorotation is trading altitude for rotor RPM by lowering the collective and then using that RPM for the slowdown when you are close to the ground.

[KLR Rico]

I will try to keep the helicopter in a low angle dive and steer it to a good location for landing.

 

Do you mean a steep dive, or a shallow one? In a steep dive you don't get the air flowing perpendicular to the rotor plane so it won't build RPM. If you don't have any cyclic authority, increase collective a bit until you can level out some, then reduce the collective again. Overall it sounds like you have the right idea.

[fixen]

Shallow dive. But the moment I drop collective it very quickly nose downwards into a steep dive with complete loss of control and rotor RPM. Should I really drop collective down completely or keep it somewhere halfway in the beginning?

 

I have done it before quite some months ago. But now I somehow just cant get it to work.

[bart]

I'm no expert here at all as to the aerodynamic forces at play, but here's what I do.....

 

First I shut the throttle (simulating an engine failure).

 

Drop the collective and pull back on the cyclic a little, which has the effect of increasing the rotor rpm, I then increase the collective to stop the rotor from over speeding and I find a balance between slight back pressure on the cyclic to maintain rotor rpm and an increase in collective to check its rpm, and aim to keep the rotor rpm in the middle of the green area on the gauge, and look for somewhere to land. If you are 2000ft + this gives you quite a bit of time for the decent and pick a decent spot to land.

 

In the decent I try to decrease forward speed a bit so once I'm near the ground I can slow to a stop just before touchdown. As the ground comes up I start to add more collective to reduce the decent and try to time it so I touchdown just before I run out of energy in the rotor.

 

It works, but required constant practice to get it right.

 

Hope this helps you out a little :)

Edited April 13, 2016 by bart

[Frank00]

Hello Huey pilots

 

Let me start by telling you that I am a noob huey pilot so I might have some things wrong.

I would like to know how you guys autorotate in DCS, but first let me tell you what I do:

 

Once I notice that the engine RPM is going down I drop the collective. I will try to keep the helicopter in a low angle dive and steer it to a good location for landing. When close to the ground I flare and pull the collective.

 

But what happens in DCS. The moment engine RPM is going down and I drop the collective, I drop like a brick. Cyclic inputs do nothing and rotor RPM keeps going down. When I increase the collective a bit the rotor rpm goes up a bit, but not enough and I still drop like a brick. If I increase the collective even more the rotor RPM drops again and I fall like a brick.

 

I thought that the whole idea behind autorotation is trading altitude for rotor RPM by lowering the collective and then using that RPM for the slowdown when you are close to the ground.

 

You must to keep rotor RPM in the green arc and for this you must sometime use the collectif and the cyclic to keep a speed of 65 kts. Near the ground do a flare (pulling cyclic) and use collectif jsut after to land smoothly and safe :D

[KLR Rico]

Shallow dive. But the moment I drop collective it very quickly nose downwards into a steep dive with complete loss of control and rotor RPM.

 

Gotcha. Yes, you can't really drop the collective to the floor right away otherwise you loose all cyclic. There's a balance somewhere in there.

[ESAc_matador]

Forward speed at 80 knots during descent....at 100 ft start reducing, at 20 ft flare and pull colective.

[Charly_Owl]

[ame]

[/ame]

[GunfighterSIX]

The correct procedure out of the US Army ATM

 

2. Procedures.

a. Maintain entry altitude and airspeed as directed until reaching the entry point. Initiate the maneuver by lowering the collective to the fully down position. Retard the throttle to engineidle stop, and adjust the pedals to maintain trim. Maintain ground track while crabbing (above 100 feet) and slipping (below 100 feet) the helicopter. Adjust the cyclic to attain an 80-knot attitude. Before reaching 100 feet AGL, ensure that a steady-state autorotation is attained. If it is not attained, execute a go-around or terminate with power as appropriate. A steady-state autorotation means that—

 

(1) Rotor RPM is within limits.

(2) Aircraft is at the correct airspeed.

(3) Aircraft is descending at a normal rate.

(4) Aircraft is in a position to terminate in the intended landing area.

 

b. At approximately 100 feet AGL, apply aft cyclic to initiate a smooth, progressive deceleration. Maintain aircraft alignment with the touchdown area by properly applying pedals and cyclic. Adjust the collective, if required, to prevent excessive rotor RPM. At approximately 15 feet AGL, apply sufficient collective to control the rate of descent and ground speed. (The amount of collective applied and rate of application will depend on the rate of descent and ground speed.) Adjust the cyclic to attain a landing attitude just before touchdown and apply collective as necessary to cushion the landing. After touchdown, maintain ground track alignment with the pedals. When the aircraft has come to a complete stop, lower the collective and neutralize the pedals and cyclic.

Edited April 14, 2016 by GunfighterSIX

[Xtrasensory]

The pitch down moment is caused by the drop in collective. Apply a little aft cyclic to maintain the helicopters attitude simultaneously while lowering the collective.

You are probably to slow with lowering the collective while rotorspeed decays, the lower the RPM the less your control inputs will have effect.

 

So either try entering the autorotation with the procedure Gunfighter Six described (lower collective first, then retard throttle) or if you simulate an actual sudden engine failure, be quicker with lowering the collective and apply aft cyclic to keep the attitude.

[Robert31178]

Lol....thnaks for the help Owl :-) J/k......

 

what is the correct rate of decent for the auto? I've noticed that when I keep it in the green for rotor RPM and also at 80kts that I am falling at 2000+ft/min?

 

~S

[Robert31178]

Aye aye Vertical. Thank you!

[Robert31178]

Just an update on my progress in auto's.....I noticed that for some reason when I turn force trim off for loss of hydraulic practice that I can fly more stable? So I messed around with it and here's what I found:

 

I've noticed that while using the force trim during auto's that 1) it takes me longer to get the helicopter out of it's terrify nose dive, 2) when using force trim I seem to fight to keep the helicopter at 80kts as it feels like it wants to hang out around 60kts, and 3) by resetting the trim for zero set and flying the aircraft that it doesn't pitch up quit so bad when I flare at the bottom of the maneuver.

 

I started applying this to a wider number of maneuvers and low and behold I seem to be using the force trimmer less and less for maneuvers. I'll keep it for level flight and for slower descents, but anything requiring finesse I'm going without and I am finding I can do more advanced maneuvers waaaay smoother.

 

Anyone else messing around with this?

 

~S

[Beazle]

Just an update on my progress in auto's.....I noticed that for some reason when I turn force trim off for loss of hydraulic practice that I can fly more stable? So I messed around with it and here's what I found:

 

I've noticed that while using the force trim during auto's that 1) it takes me longer to get the helicopter out of it's terrify nose dive, 2) when using force trim I seem to fight to keep the helicopter at 80kts as it feels like it wants to hang out around 60kts, and 3) by resetting the trim for zero set and flying the aircraft that it doesn't pitch up quit so bad when I flare at the bottom of the maneuver.

 

I started applying this to a wider number of maneuvers and low and behold I seem to be using the force trimmer less and less for maneuvers. I'll keep it for level flight and for slower descents, but anything requiring finesse I'm going without and I am finding I can do more advanced maneuvers waaaay smoother.

 

Anyone else messing around with this?

 

~S

 

1) if are getting a nose dive when you dump the collective it is simply because you don't pullback on cyclic fast enough. As you drop the collectice you should, at the same time bring the cycle aft

2) in autorotation your reference speed is 60 kts not 80 kts like a lot of guys in DCS seems to think. If you want to reach a further spot ok go pick 80 kts to increase gliding distance but you should never flare at that speed! Flare speed on a Huey is 55-60kts. Otherwise youre just going to float for ever abd won't be able to land without forward speed

3)force trim should always be on so if I'd be you I would get use to fly with it in on position!

 

Keep it up man! And if you want more info son't hesitate!

[Robert31178]

Send all you got, I'm a thirsty sponge for Huey at this point. Pretty much stopped playing my other two games and also quit flying my other aircraft to focus on becoming super good in this helicopter.

 

Neither would be caught dead playing a sim, but both of my stepdads flew Huey in Vietnam, my first stepdad was a 3 tour pilot, twice in Hueys and once in Mohawks, and my current stepdad was a medevac pilot. I've grown up being in love with this particular helicopter simply because it played such a huge role in shaping who these men are. Absolutely wonderful module and I want to be great at it!!

 

~Rob

[Beazle]

Yeah!!! The Huey is just an awesome module!! I love how close it is from reality!! I am aspiring myself for being a Huey pilot one day(or maybe more its civilian equivalent the 205). When I first started using DCS, I wanted to learn to fly fighters jets but bought the Huey too because choppers are the best and I never or barely touched my mirage aha always flying with the Huey.

 

What I would really want to be implemented in it though is, engine damage. There is too many people torquing the Huey at 54 psi and leaving it there for the whole flight aha!!

 

If the right engine could be in the airframe, that would be cool aswell hehe!!

 

I love practicing autorotation in DCS!! It is really realistic(Maybe the RRPM have a tendency to give you more margin than real life. But I only fly 206 in real life so maybe it does have more inertia in the system!! But still all the motion, flapback, altitude velocity chart are pretty damn good!!

 

I like to practive engine failure in such position where in real life it would end up in damaging the aircraft!! It's great for my reflexes and I keep my hand fesh with emergencies since I practice them only once a year at the recurent training!!

 

Anyways how's your autos coming?

[Robert31178]

I would say that yes the 205 has more rotor inertia than 206, look at the wide blades of Huey! I know from reading that it had enough momentum to auto, touchdown, then pull collective and the torque still remaining would spin the A/C 180.

 

do you have access, and maybe could put a link to, a good Huey manual for the H (205)? It would be VERY helpful to me, especially if BST made this to match the actual Huey.

 

~Rob

[Beazle]

I would say that yes the 205 has more rotor inertia than 206, look at the wide blades of Huey! I know from reading that it had enough momentum to auto, touchdown, then pull collective and the torque still remaining would spin the A/C 180.

 

do you have access, and maybe could put a link to, a good Huey manual for the H (205)? It would be VERY helpful to me, especially if BST made this to match the actual Huey.

 

~Rob

 

The 206 as enough inertia to take off again and do a 180. Don't mixed torque and rrpm tough aha! When the monkey quit, you have no torque at all!

 

You have to remember too that the weight counter balance the fact that their is more inertia in the system. So to create enough lift for that weight you will need to pull a lot of pitch which will create a lot of drag which will result in rrpm lost. So that is my questionning to know how it affects the the rrpm deccelaration when you start pulling pitch for the flare.

I'll ask my buddy who flies our 205 to see how it is comparted to the 206!

 

I do have the flight manual for the 205! But its directly on Bell Helicopter website. If you want, send me a pm with which info you want and I'll try sending a bunch of screenshots. I think you would like the normal iperation section.

 

Cheers

Billy

[Sandman1330]

While there is a huge amount of inertia in a 206 rotor system, there is not nearly enough to lift off and do a 180. Somebody has been reading too much Chickenhawk. ;)

 

As a matter of fact, there is - I've seen it done.

 

Some models have weights added to the tips of the blades to improve inertia. I believe the model I flew was so equipped.

[Ironwulf]

Just a question/confirmation.... you do not need to (manually) disengage the rotor system from the (dead) engine- this is automatic, yeah?

[Sandman1330]

Just a question/confirmation.... you do not need to (manually) disengage the rotor system from the (dead) engine- this is automatic, yeah?

 

Yup - there’s a sprag clutch that (functionally if not mechanically) acts like the pedal clutch on a mountain bike. You pedal and provide power, it engages and drives the wheel. Stop pedalling and let it freewheel, and it disengages and lets it coast. (The pedals are the engine and the wheel is the rotor in this analogy)

 

This is why, even with the engines running, an aggressive flare or low collective setting can allow the rotor to exceed limits on the high side, while the engines just sit at idle.

Edited February 19, 2019 by Sandman1330

[Implicit]

Speakling of disengaging the freewheel.

The only way I can get it to disengage is cutting the fuel. Rolling off the throttle (With or without the Governor switch on EMER), keeps the engine pegged to the RRPM.

Seems like a bug to me as I've seen it behave correctly in some of the older DCS Huey Auto videos.

It doesn't, however, appear to be influence the autorotative performance much.

[Deezle]

Speakling of disengaging the freewheel.

The only way I can get it to disengage is cutting the fuel. Rolling off the throttle (With or without the Governor switch on EMER), keeps the engine pegged to the RRPM.

Seems like a bug to me as I've seen it behave correctly in some of the older DCS Huey Auto videos.

It doesn't, however, appear to be influence the autorotative performance much.

This has been known about forever, the devs have just ignored it.

 

[rmakowsky]

One issue with the module is the gigantic pitch coupling to the collective.  So when you lower the collective  your nose pitches down rapidly.  (On the other side, when you raise the collective, the nose pitches up rapidly).  

So when starting an autorotation, you lower the collective and the nose pitches down severely.  So much so that only a very strong aft cyclic input will keep the nose level so you can build RPM back.  Without a rapid pitch input you will be chasing the nose low attitude all the way to the deck.  

 

Pitch coupling of the magnitude in the sim, is not correct.