Need Help (Big Time) - Approach Speed Control and Landing

[jjohnson241]

Hi Guys,

I have yet to land successfully (by that I mean not by accident). I'm having problems with contolling speed during approach and / or entering a hover before landing. Efforts typically result in a smoking hole in the ground.

I've attached a TRK file for your giggles and analysis.

Hopefully someone can help me with some pointers.

Thanks.

Landing Crash.trk

[Yurgon]

I've attached a TRK file for your giggles and analysis.

Hopefully someone can help me with some pointers.

 

The flight looked pretty good, except for the crash, obviously. :music_whistling:

 

The training videos that come with the Huey, "Takeoff" and "Landing", explain quite well what happens to the helicopter during the transition from a hover to forward flight and vice versa.

 

In a nutshell, as you pick up speed, the rotor blades become more efficient because they travel through "clean" air. That's when all the shaking starts, and after that you'll have "Effective Translational Lift" (ETL). As soon as that happens, the Huey tends to climb, so you have to lower the collective if you want to maintain your altitude.

 

More importantly, the exact same thing happens the other way around as you slow down to a hover. At approximately 30 to 20 kts, you'll lose ETL, which means you'll lose a lot of lift. At that point you must counter the loss of lift by increasing the collective quite a bit.

 

It really is a challenge to make this whole process look good, but for starters, as soon as the chopper starts to shake while slowing down, bump the collective up. If you gain altitude, you've good a lot of time to correct for that later.

 

But if you don't increase collective enough, you'll get into my very dear friend, the "Vortex Ring State" (VRS), where the rotor system basically pumps through the same, "used" air. To recover from VRS, you must add collective (in the Huey, that is. In the Black Shark, you actually MUST drop the collective!) and you should try to gain forward air speed. Needless to say that this will fail if your altitude is too low, and this is exactly what I saw happen in your track.

 

As a rule of thumb, keep your rate of descent above 500ft/minute to avoid VRS altogether. As soon as you drop to 1000ft/minute, you're in deep trouble and your reflex should be to ignore anything else, raise collective and avoid VRS. This, as I hope is clear by now, refers to flight in or near a hover. As long as you have sufficient forward airspeed, you can drop at 3000ft/minute and easily recover by just pitching back a bit.

 

Finally, I'm no RL pilot, so take all of this with a grain of salt and just keep practicing. I'm sure you'll be doing rooftop landings in no time. :thumbup:

[jjohnson241]

Thanks Yurgon.

I've viewed the training vids so many times now that I can recite the narrative.

Question.. how do you control the decrease in speed as you lose altitude during the approach?

For some reason, I find myself carrying too much speed and attempting to correct that with the cyclic (pitch up), only to gain altitude when I just want to slow down.

Thanks again for the tips.

[Yurgon]

I've viewed the training vids so many times now that I can recite the narrative.

 

I have that with some of the campaign missions, for a variety of reasons. :D

 

Question.. how do you control the decrease in speed as you lose altitude during the approach?

For some reason, I find myself carrying too much speed and attempting to correct that with the cyclic (pitch up), only to gain altitude when I just want to slow down.

 

Yup, that's definitely a problem I'm having, too. The "proper" way to do it is to lower the collective in such an instance, but just so much that it counters the helo's tendency to gain altitude. I think it's just a matter of practice.

 

I've crashed during many campaign missions for this exact reason, but things massively improved after I discovered the mission Sample: huey troop pickup/dropoff via radio command. I've flown it twice, never got a MISSION SUCCESS, but have landed so many times in a short time that it really helped to train the muscle memory.

 

And I think that's what it's all about: muscle memory, having hands and feet do the right thing without the brain getting in the way all the time. :)

 

You could create a simple test case where you try to slow down to a hover at 1000ft, so that if something goes wrong you can easily recover and try again instead of crashing all the time. Accelerate to ~80 kts, then gently slow down and try to maintain altitude by leaving the cyclic mostly alone and working with the collective.

 

Then do the same thing at 100ft several times, and then, finally, near ground level. Don't worry if you gain some altitude, just make sure you don't lose any unless you want to.

 

The Huey is by far the most challenging aircraft I've ever flown in a sim. I try to get as much stick time as possible and work on one problem at a time, and I've loved the Huey every stop of the way, even when it tried to kill me (and kill me a lot it did!). :D

[jjohnson241]

I downloaded that mission but have yet to fly it. I'll certainly give it a shot. It appears to me that the formula is decrease collective coupled with back pressure on the cyclic until slow forward progress (crawl slow) is reached at low (how high?) altitude and maintain until IGE is achieved. Then increase collective slightly (how much?) to compensate for loss of lift until ground contact.

We'll keep pluggin (and probably dying).

Thanks again for your help.:)

[Yurgon]

It appears to me that the formula is decrease collective coupled with back pressure on the cyclic until slow forward progress (crawl slow) is reached at low (how high?) altitude and maintain until IGE is achieved.

 

Almost. The sudden loss of lift, accompanied by shaking, will occur at ~20 kts. That is when you must increase collective and keep your eyes peeled on the VVI to keep it in the 0 - 500ft descent range.

 

IIRC, hover IGE can be achieved at about half the rotor diameter, so that's just around 25ft max.

 

Then increase collective slightly (how much?) to compensate for loss of lift until ground contact.

 

How much? That's a good question and really also the answer to the problem. I can't really give an approximation in percent. You should closely monitor the VVI and adjust the collective so that the rate of descent stays well above 1000ft/min. The VVI is the single most important instrument in this situation.

[jjohnson241]

Ok, think I understand now.

Off to battle the "shakes".

Thanks.

[wess24m]

Hi Guys,

I have yet to land successfully (by that I mean not by accident). I'm having problems with contolling speed during approach and / or entering a hover before landing. Efforts typically result in a smoking hole in the ground.

I've attached a TRK file for your giggles and analysis.

Hopefully someone can help me with some pointers.

Thanks.

 

Not sure if it will help but

one of my videos where I do a full approch from speed; no voice over but some good music and you can watch my control indicator in the top left. I also have my take on hovering, getting to speed, and coming out of ETL with a landing in a different video as well.

[jjohnson241]

Thanks Wess24m.

I'd be interested in watching all the videos you mention in your post.

BTW, your tutorial videos are excellent and have gotten me off the ground at least.

[TimeKilla]

This is what i do

 

Line up at 150 ft, 300 yards from runway speed 80 knots once at 100 yards pull up hard while decreasing collective to slow speed, Once at 10/20 knots and shaking while you're attitude is dropping heavy as you're entering near hover.

 

Up collective until level flight (this has to be done very fast or you will enter VRS.) If you miss and end up in VRS, as you are travelling forward slowly all you need to do is roll.

 

After that you will be over the runway and in ground affect at 10 ft above runway travelling at 10 knots or less then you will just slowly lower collective while pulling back slighting and losing attitude at 2m/s and flare and land.

 

The even easier way to land is just skid land this can be done at 120 knots and that's no joke as long as you don't land to hard on the skids and are lined up right it will skid land then once collective is down pull back to slow you're self down while on ground.

Edited May 26, 2013 by TimeKilla

[fjacobsen]

When entering VRS You should definitly NOT raise collective, but rather lower it. Otherwise You will simply "pump" even more into the downwash in wich You are trapped.

 

So lower collective and gain forward speed is the best solution.

[jjohnson241]

Timekilla and Fjacobsen,

Thanks for the tips. I think the objective is to avoid VRS (which I have yet to achieve). I've experienced exactly what you say in terms of the effect of raising collective while "trapped" in VRS, that is, a big fireball landing. I have not tried to roll out of VRS and I'll give that a shot as undoubtedly I'll have that opportunity.:cry:

[SimFreak]

During approach when speed dropping bellow 40 indicated, make sure VVI is less than 300. That will allow you to catch VRS before it becomes unrecoverable.

 

 

http://www.youtube.com/watch?feature=player_embedded&v=anT3kx-ci3Y

[Yurgon]

During approach when speed dropping bellow 40 indicated, make sure VVI is less than 300. That will allow you to catch VRS before it becomes unrecoverable.

 

 

http://www.youtube.com/watch?feature=player_embedded&v=anT3kx-ci3Y

 

Yup, with 300 on the VVI, the pilot should be on the very safe side.

 

Nice vid! :thumbup:

[jjohnson241]

Well, as a result of the help offered here I was able to land the beast and walk away. :joystick:

The VVI tip along with Simfreak's video did the trick, although I still need alot of work in coordinating the collective with cyclic when the "Shake" starts.

 

SimFreak.. any chance you could redo your video with control inputs on?

 

Thanks again.

[SimFreak]

Here's a remade video with controls enabled. Little ruff on controls due to flying under influence....good luck

http://youtu.be/DoThVnuda7w

[jjohnson241]

Thanks much Simfreak.

 

Edit:

Just watched your video Simfreak and all I can say is you fly better drunk than I fly sober.

Thanks again.

Edited May 26, 2013 by jjohnson241

[Mogster]

I'm having exactly the same issues, moving around and hovering near the ground is OK, transition from high speed flight to landing is the problem.

 

Slowing down seems to lead to me climbing which I counteract by reducing power/collective. I loose speed/height but enter VRS, by that time I'm at dead men's corner and ready for a fiery death :(

 

I'll try not descending too fast.... I don't want to resort to sliding landings all the time as it doesn't feel particularly realistic.

 

Edit ...................................................................................

 

I feel I'm getting to the root of this now and its at least partly a controller issue. I use an MSFF2 stick with X45 throttle and Saitek pedals. The sticks fine but using the throttle as collective I'm trying to make tiny adjustments using the first half inch of travel, the mechanism isn't really up to it. I need to set up a custom curve not set around the centre though as with a normal axis.

Edited May 27, 2013 by Mogster

[jjohnson241]

Mogster,

Misery loves company.

I find that while descending and slowing down, once the "shake" starts (about to enter VRS), you need to apply quite a bit of collective to avoid VRS. And yes, if you don't manage the cyclic, you'll gain altitude.

Watch Simfreak's video (the one with control inputs on).

Also, manage the descent to not exceed 300 m/s (monitor VVI gauge).

 

After that all said, I'm still digging flaming holes in the ground half the landing attempts.

 

Practice I guess.

[Bulletstop]

This thread helped me a hell of a lot. I now understand I have to be thinking a lot further ahead on my landing. I also start dumping altitude further out also. That youtube vid did it for me No more holes in the ground from me entering into the VRS. Thanks guys :)!!

 

 

Bullet

[Chelco]

In my hands, the critical airspeed where hell breaks loose is 40 kts. I got over it finally, although my airspeed control is still bumpy at <40 kts.

 

http://forums.eagle.ru/showthread.php?t=107261

 

And a video of my landing:

[Sundowner.pl]

Be aware, that such shallow and slow approach puts you into the "avoid" area of H-V diagram:

 

 

If you loose power on that approach, you will not make it to the landing spot. I've actually had such occurrence two days ago - I'm flying one mission I made, and constantly change - what I did, was to remove all of the targets from Sukhumi airport... but forgot to remove a single BRDM. Few flights later I'm landing at the Sukhumi airport, and suddenly I'm thrown into the co-pilot seat, and lost all power. I'm keeping the approach speed at 50-60kts pretty well into the landing spot, and approach angle is close to 30° so I still had plenty of room for autorotative landing... although the helicopter was shot to pieces on the ground :music_whistling: