Thank you very much flyingbob for this new resource, and I will be installing it shortly. I'm finding that it is very hard to judge things right now and I clearly need something like this to get me over the hump because I'm starting to be a little frustrated, especially after watching that Snoopy helicopter video from the other thread! To answer a question I posed above, and in answer to myself, the DCS Black Shark probably isn't the best trainer because it is a coaxial rotor without all the quirks associated with a more conventional heli. One question, on the gauge download page,it says FS2004 only. I suppose that it works just the same for FSX?

After several hours of practicing landings tonight with the Dodo, I am pleased to say that I've gotten a lot better now. I decided afterall not to use the training gauge (but thanks for pointing out it availability, flying_bob) and I also decided that the graduated levels of difficulty, 1 thru 5, wouldn't really be "realistic", so in the end I just decided to grit it out without aids and at max level. Little by little without really analyzing it too much I'm getting closer and closer to my landing targets (a helipad). Yesterday, I could barely land on a football field! After tonights practice, though not ready to cue up the Airwolf music yet, I'm pleased to say I'm at least within the helipad now for the last 10 tries with fairly close circling approaches. Now I need to start tightening things up quite a bit. It seems more like a concentration and confidence thing than anything else, so thanks for the good advice in this thread.

After going though this excercise, I loaded up DCS and played around with the coaxial rotored KA-50. I have to say that that copter is a LOT easier to fly than the twitchy Jetranger!

 

I'll keep practicing. I have a long way to go, clearly, but I'm glad that I finally decided to explore the realm of helicopters after all these years. The big, stable fixed winged planes were getting a little boring and it was time to shake up the experience a little bit. I hope the OP sticks with it too. I for one, am somewhat invigorated by the challenge because I am starting to see a glimmer of light now.

 

P.S. Although I understand it is completely realistic, I still don't quite get why the Ground Effect forces one to add MORE collective instead of LESS collective. Why is that? On the surface, I would think that the ground effect on a copter would provide a cushion just like it does on fixed wing aircraft...so why do I have to add more collective?

I would think that the ground effect on a copter would provide a cushion just like it does on fixed wing aircraft...so why do I have to add more collective?

 

Good to hear you getting better.

 

The helicopter do not have a wing. Time to read about helicopter dynamics..

it's just the way it work. I can sit here and explain in a lot of scientific mumbo jumbo why it happen, but you can google and read up on this yourself. there are 100's of sources available online that might explain it better then me.

 

bottom line is the blade loose downforce the closer it get to the ground (downwash and vortes). not so much air between the helicpter and the ground as it gets closer to ground. less air between ground and helicopter mean you have to increase collective to make up for "lost" downforce the closer you get to the ground. Blade work with air not with ground. You can say, as the helicopter get closer to ground air is forced out under blades (between helicpter and ground) so the effect is less air and thus less "force" thus you have to increase collective to subsititute same blade effectivness. its all about the "Lift" created by the blades. this is very elementary.

The whole science include among others (not all mentioned here)

-aerodynamic force changes

-angle of lift changes

-direction of airfoil chnages

-downwash angle reduced

-induced drag

etc etc etc..

 

It is better to read up on this phenomona yourself. English not being my mother tongue, so I rather let you read up yourself as I might say something wrong in english that could be misunderstood. Hope you understand.

 

edit

maybe someone fluent in english can explain better.

Flying_bob, that is a great tutorial video! Very nice work!

 

It's great to see more people interested in an extremely rewarding aspect of flight simming, helicopter flight. Difficult, yes, but once mastered there's nothing like it.. B)

Am wondering if you're adding more collective because you've moved out of translational lift.

Am wondering if you're adding more collective because you've moved out of translational lift.

 

yes in effect you can say so even though translational lift is 95% associated with takeoff/hoover transitioning to flying and not so much mentioned in the same sentance as landing. You lost that "extra" lift at so slow speed and close to ground. ground effect is just opposite to translation lift

 

tranlational lift

helicopter blade are designed to push air out of the way. As the helicopter moves forward and gains speed, the air becomes less turbulent around the body and rotor, allowing for the production of better lift through translational aerodynamics that creates a sort of forward inertia for the vehicle.

 

ground effect

the ground effect is the opposite of translational lift, and is a opposite effect experienced as the helicopter wants to land. As the downward thrust hits a solid surface, it creates an increased upward thrust for which must be compensated. This can also occur in flight/hoover taxi if the helicopter passes close to a building or other solid areas as runway. therefore taxi over uneven terrain can become nightmare to manage these forces as they change all teh time

 

ground effect is explained nicely here with graphics showing what hapen when there is limited air between helicopter blades and ground

 

http://www.dynamicfl.../ground_effect/

On the surface, I would think that the ground effect on a copter would provide a cushion just like it does on fixed wing aircraft

 

Your right. In real life, that is exactly how it works. That's why a helicopter has IGE (in ground effect) and OGE (out of GE) hover performance charts.

 

Coming in to land, as you slow down on the approach you come to a transition point where you have to bring in more and more collective to maintain the approach path while at the same time nudging the cyclic forward to keep the forward rate going (increasing the collective will make the nose pitch up and will stop the forward pace in an approach).

 

On an approach, you will always have the most collective in the end - ie in the hover. However, less air between you and the ground will reduce the downflow, giving you less induced drag in the rotor system.

 

So a low hover is beneficial from a power standpoint as a hover IGE requires less power (less collective) as opposed to a OGE hover.

 

Am wondering if you're adding more collective because you've moved out of translational lift.

 

Correct - you are getting more and more on the back of the power curve as you slow down to zero IAS (say from 60-40 knots depending on the aircraft type), requiring more power as you slow down in order to maintain the approach angle.

 

have to increase collective to make up for "lost" downforce the closer you get to the ground.

 

I am sorry but this is absolutely wrong. The reason you are increasing the collective is because of decreasing forward airspeed.

Think of the rotor disk, rather than each blade, as an airfoil equivalent to a wing, and then remember that in a FW, flying is about angle of attack, which is about angle of chord to the relative wind (in many cases then, the angle of the wing relative to your flight path). Think how much more power you need to keep flying at high angles of attack. Then think how high your angle of attack becomes in a heli as the rotor disk moves from forward flight into a hover (picture the angle of the rotor disk to the flight path as you slow and begin to hover). It quickly moves from something like a normal FW AoA while moving forward at even 40 kts to something close to 90 degrees as you hover, at which point a FW would long ago have fallen out of the sky.

 

I think that's the simplest way to understand the need for more power as you transition into very slow flight and vertical hover. There's more at work of course, which is why a heli can hover at all and a FW can't. But that's part of the reason for the need for additional power.

I am sorry but this is absolutely wrong. The reason you are increasing the collective is because of decreasing forward airspeed.

ok I will rephrase because you taking again out of context and maybe I assume people will be able to put 1+1 together, but alas it do not seem so.

so here it is..

"have to increase collective to make up for "lost" downforce the closer you get to the ground at very slow airspeed such as landing"

 

"lost" downforce can be interpreted as you like that is why it is in inverted commas. My sentence above is nothing else then what you sayd

"On an approach, you will always have the most collective in the end - ie in the hover. However, less air between you and the ground will reduce the downflow, giving you less induced drag in the rotor system."

 

happy now ?

maybe my way of saying something can be interpreted other way round, but I know what I mean even if it comes out scew in english then so be it. I think 99% of people here understand what I try to say.

 

and on that note, please continue your education here. I am done..

No, what I said was exactly the opposite.

 

Whilst you said a lot of things, not much of it made any sense though. Here it is again:

 

The helicopter do not have a wing. Time to read about helicopter dynamics..

it's just the way it work. I can sit here and explain in a lot of scientific mumbo jumbo why it happen, but you can google and read up on this yourself. there are 100's of sources available online that might explain it better then me.

 

bottom line is the blade loose downforce the closer it get to the ground (downwash and vortes). not so much air between the helicpter and the ground as it gets closer to ground. less air between ground and helicopter mean you have to increase collective to make up for "lost" downforce the closer you get to the ground. Blade work with air not with ground. You can say, as the helicopter get closer to ground air is forced out under blades (between helicpter and ground) so the effect is less air and thus less "force" thus you have to increase collective to subsititute same blade effectivness. its all about the "Lift" created by the blades. this is very elementary.

The whole science include among others (not all mentioned here)

-aerodynamic force changes

-angle of lift changes

-direction of airfoil chnages

-downwash angle reduced

-induced drag

etc etc etc..

 

 

If you are hovering, the rotor disc is more efficient with less air between the rotor disc and the ground. It is called ground effect. And it is the exact same thing for helicopter as it is for an airplane.

 

Apparently we agree that one needs more collective as one comes in to a hover, you just don't seem to understand why that is.

 

That's all. Didn't mean to step on your toes there.

"have to increase collective to make up for "lost" downforce the closer you get to the ground at very slow airspeed such as landing"

 

Except that the loss of lift has nothing to do with being close to the ground. It has to do with reduced airspeed. The loss of translational lift. Sorry, flying_bob, but your explanations are so far removed from what I learned that I don't understand them at all.

 

Hook

Except that the loss of lift has nothing to do with being close to the ground. It has to do with reduced airspeed. The loss of translational lift. Sorry, flying_bob, but your explanations are so far removed from what I learned that I don't understand them at all.

 

I am so glad I am not the only one

Let's see if I can explain this the way I learned it, in layman's terms. I'm intentionally only focusing on the primary control inputs, not all the things you have to do to keep the helicopter straight.

 

You're sitting on the ground, engine running and ready to take off. You add collective until the helo gets light on the skids, then a bit more until it rises into a hover. At this point it's sitting on a cushion of air, which is the ground effect. Apparently this cushion is quite substantial, making it easy to maintain a given altitude in a hover near the ground, although I've never seen this modeled in any helo sim I've ever tried.

 

You nudge the cyclic forward and the helo starts to move. As you gain speed the helo will "fall off" the air cushion, and you have to add a bit of collective to keep from descending. After gaining a bit more speed, the helicopter will start to climb as you enter "translational lift".

 

During landing the opposite happens. As you slow, you lose the translational lift and need to add a bit of collective to compensate. As you slow to a hover, you get into the ground effect cushion and you need to reduce collective.

 

You'll get this cushion of air near the ground, but not at say 100 feet, because near the ground there's nowhere for the air to go except sideways and it gets compressed. At 100 feet the air has more freedom and can travel downward as well, so there's no ground cushion.

 

Hook

I guess the curve for translational lift must be quite substantial and steeper than I realize because it seems even decellerating from a smallish forward motion of 5 to 10 knots and a very shallow approach angle, I am surprised by the amount of collective I have to pour on--like from 50% to 60%. I'm happy to say that I've gotten the motor skill memory down now, so I'm doing it subconsiouly now, but that was one of the earlier things that was giving me problems. Right now I'm practicing doing approaches faster and steeper and trying to discipline myself to pick an aim point a little beyond---I'm typically coming up about 5 feet short consistently. I guess practice, practice, practice....

 

Can anybody point me to some good EZdok Vibration profiles and/or Accufeel settings that would be good to use with a JetRanger? I'll check over at Hovercontrol in the meantime.

I'm typically coming up about 5 feet short consistently

 

That's typical the first times in the realworld too. Getting the approaches down and getting the proper feel and understanding can take some time. But like you say, muscle memory and repetitions, repetitions, repetitions.. keep on practising, suddenly the Eureka moment comes.