Realism?

[Cralis]

I am battling to keep the TREX 450SE in a stable hover. Infact, can't do it right now, but will get it, I am sure.

However, when I switch to the LAMA as an aircraft type, I find it mUCH easier than the real one. More stable and reacts better to my inputs. Also, you can be in fast forward flight, and then pull back full on the elevator to slow down, and down slightly on the throttle, and it works.

In real life you try that, and the balance bar strikes the blades, and you have a wipe out.

I have the Esky LAMA. Is the version in the sim different and therefore, in real life, maybe more stable?

This worries me, as if I am battling with the TREX in the sim, I am going to pay quite a lot of money to fix the real one when my maiden flight comes up... I was hoping that if I coulf control the TREX in the Sim, I would manage in real life, but judging by the Lama... this won't be the case...

Or will it?

[Smoothound]

It won't be a problem

It will feel different on the real thing.

You probably won't have the urge to go screaming round the skies on the real thing when you transfer just because you can on the sim because of the wallet factor

You will go nice and gently and learn to fly the real thing just as you did learning on the Sim you will just know more about how to fly the thing than going straight into the real thing

[moyesboy]

The trex in phoenix is realistic in the way it transits from forward flight to hover and back again.
It is less stable in the hover than my trex.
The tail is nailed on the sim, and it isn't that absolutely nailed in real life. It is pretty much nailed while hovering, but with big pitch applications there tends to be some tail movement. Perhapos I need to finally upgrade my plastic tail assembly!

If you have 2200-2400 head speed you will not get any blade/boom strike problems on the trex unless you contact the ground.
Make sure the blades are tight enough in the grips as it is when they swing in the grip as the rotor slows that they hit the boom.
With the head going at 2400 I have bounced on the ground hard enough to break the (weak x400) undercart without any other problems (till it had to land with a broken uindercart!).
Basically you have to hit the ground to break the trex, in idle up you can slam the sticks about in the corners and you wont break it, provided you can recover control afterward!
If yu have -10 with throttle closed in normal mode, then you can get a boom stick if you "chop stick". You need to limit negative pitch to -2 degrees in normal mode.
Of course if you are high up and go to apply full negative in normal - so the rotor stops, then you are toast!

[Cralis]

Thanks guys.

Another quick question then. Moyseboy, you mentioned FF transition. With the Lama, when you put forward elevator to fly forwards, and then release the stick to centre, the helis nose lifts and it goes back into a hover attitude.

With the Trex, this doesn't happen. You go into forward flight, but letting the stick go back to centre doesn't bring the nose up. It just stays down and you gather speed until it stops in a nearby hedge... Is that normal, and if so, how come the Lama returns to balanced flight, but the Trex stays with nose down, and you need to basically balance it yourself?

Also, you mentioned being high, and cutting the engine. With the blades being set to allow full +10 to -10 pitch, you can do an autorotation if the engine fails.

But it seems if you only allow -2, the heli crashes with you flare... is that riight?

[andylinney]

The Lama is designed to be positively stable, the top set of rotors are controlled by the two mass balances on the flybar. Next time you fly it, put in a hard left or right cyclic command and you'll see the top rotors acting in the opposite direction to dampen the movement.

This creates a stability that keeps the heli from moving any more than a few degrees in any one direction, as you release the forward command the gyroscopic effect of the top rotor / flybar automatically counters the forward effect of the lower, directly controlled rotor.

I'm no expert on other heli's but the flybar on the 'rex only acts in this fashion in a very limited way, leaving almost all of the control to the pilot. Therefore, an input on the 'rex is not damped out to quite the same degree as equally, there is no mechanism to automatically return the heli to straight and level.

[moyesboy]

Thats pretty much right.
The collective pitch heli has neautral stability, it stays at the angle you put it.
The fixed pitch heli has natural stability and wants to return to horizontal.

If you try to fly your lama in a gusty wind, then you'll see that it blows about all over the place.
with the collective pitch heli then the wind blows past it and it stays horizontal, it is just buffetted sideways a little but doesn't tip at all.

One analogy is to compare the fixed pitch heli with a high wing trainer fixed wing. The trainer eventually levels its wings up and returns to straight line - wheras a low wing 3D plane will stay at the angle of bank you last put it at.

The flybar and bell hiller mixing does add stability and makes it more predictable and controllable but the effect is to make it neutral and stay at the angle it is put. The full explanation of how the flybar mixing works is very complex but there is a good series of articles by colin mill, the boffin behind CSM gyros, at the bottom of this webpage page if you want to try to understand it:
http://www.w3mh.co.uk/articles/articles.htm

As regards the realism of Phoenix, don't wory the way the models fly is pretty realistic to me.

[ajenkins]

Thats pretty much right.
The collective pitch heli has neautral stability, it stays at the angle you put it.
The fixed pitch heli has natural stability and wants to return to horizontal.

Actually this doesn't have to do with fixed pitch versus collective pitch, it has to do with coaxial rotor versus single main rotor helis. A FP heli such as an ESky HoneyBee is neutrally stable as well. However coaxial rotor helis such as an ESky Lama or E-Flite Blade CX are designed to be positively stable. In fact you literally can't get them to bank more than 10 or 20 degrees, and when properly trimmed and assuming no wind, they'll hover pretty much in place hands-off. No single-main-rotor heli that I know of behaves this way, whether FP or CP.

As for the original question, I found the Lama model in Phoenix to be better behaved than the real coaxial helis I've flown, in just the ways you described. The bigger helis like the Trex though are much closer to real. If anything it's a little easier to hover a real mini heli than the trex 450. I'd guess the Phoenix folks just didn't put a lot of effort into getting the Lama right, rightly in my opinion since you don't really need a simulator to learn to fly coaxials anyway.

[gazza]

Out of interest although I find the 450SE flight model very accurate, going into edit mode & increasing hovering stability to 100% makes it that little bit tamer-Kind of like it is with the flybar weights fitted