Helicopter Help Needed

[Mick]

... It's vital to work the FDE that there is a relatively flyable bird, btw. Like a complete model, pretty decent panel, like that. Gotta fly it to test it Textures, sound, the little details, not really important, you know? just so long as there are usable gauges, and I'm not sitting on nothing, I'm good. It kinda messes with my pea-brain to fly around sitting on air, you know? Pat

The bird is flyable now, at least for test purposes. The present flight model is adapted (without great success) from the AlphaSims Sikorsky S-55/H-19/HRS with only a near-minimum of changes: contact points, second engine installed, UI sections, lights, not much else. The performance is like the S-55, which was about half as fast as the S-56.

The worst problems are a strong right turn tendency and an extreme nose-down attitude in forward flight at even fairly low speeds. David followed the earlier suggestion to angle the rotor shaft four degrees back, but that's a tiny fraction of the excessive pitch angle. Alpha provides a rotor trim gauge for the S-55 that allows trimming out a left turning tendency but it doesn't work in the direction we need.

Two 3D models are finished and the other needs some final work. The 2D panels are almost finished except for a couple items that should be added to the panel background that are giving me fits. The VC is built but not yet painted. The H-37 VC panel needs tweakage and the HR2S VC panel isn't started yet. The sounds, a mash-up of the AlphaSims S-55 rotor sounds and Nigel's twin R-2800 sounds from Milton's Ventura are finished and sound great. Almost twenty skins are painted.

So that's where we are now. With work to be done on the HR2S 3D model, the 2D panel needing final tweaks, VCs to be finished and painted, we have plenty to do before we have to dive into the flight model. You will almost certainly be all healed up by the time we have to stop procrastinating on it, especially since both David and I have been hit with true life issues that are seriously impacting out hobby time. I think it's a corolary of Murphy's Law of FS Modeling that any time you post a public request for help, something will happen that keeps you from paying as much time and attention as they deserve to the answers you get.

... it can be made realistic, but still easier to fly than the real. As far as I know, however, programming an AFCS, or even a control assist type system is a real adventure, and I am pretty much a tyro at HTML. Best I can offer is to make the FDE as though the controls are assisted by making it fly like there is. Does that make sense? Pat

Yes, it makes sense! We don't need, or even want, an actual, functional Automatic Stability Equipment (HR2S) or Lear Autostabilization System (H-37B). We're just happy to have an excuse if our helicopter isn't as hard to fly as some might think it should be.

Promise not to laugh! I was on the bottom step of a low, two step, step-stool... Pat

No laughter! My sincere sympathy for your injuries and the prolonged recovery period. I've known of other folks who got seriously mangled in home accidents. I chuckled at your mention of how long it takes you to type in your present condition because I'm typing this one click at a time with the mouse on the on-screen keyboard, necessary because a certain cat, after performing an elegant full body keyboard flop, is laying against the keyboard with his head on my mouse hand. But you're stuck with your situation for now, while I could escape mine if I were to risk moving the cat. That would involve a certain amount of ripped, torn flesh and flowing blood, but at least I have the option.

 

[PhantomTweak]

The worst problems are a strong right turn tendency and an extreme nose-down attitude in forward flight at even fairly low speeds. David followed the earlier suggestion to angle the rotor shaft four degrees back, but that's a tiny fraction of the excessive pitch angle. Alpha provides a rotor trim gauge for the S-55 that allows trimming out a left turning tendency but it doesn't work in the direction we need.

Actually, there are ways to fix these sorts of troubles, as well as the top speed. A mix of .air file and aircraft.cfg entries. One thing David should have done is set the static angle of the main rotor forward, not aft, and then adjust the .air file settings to match. See my examples to find the setting I mention. The left turn tendency can be adjusted with the tail rotor settings in the .air file. The ease or difficulty to fly has to do with the low realism settings, placement and weight of the station loads, and MOi values. The station weight values and placement can affect the attitude as well.
All this "stuff" is complexly interrelated and one small detail can affect something that doesn't seem at all related to it in any way. Be cautious about what you adjust, how much, and in which numeric direction.

I chuckled at your mention of how long it takes you to type in your present condition because I'm typing this one click at a time with the mouse on the on-screen keyboard, necessary because a certain cat, after performing an elegant full body keyboard flop, is laying against the keyboard with his head on my mouse hand. But you're stuck with your situation for now, while I could escape mine if I were to risk moving the cat. That would involve a certain amount of ripped, torn flesh and flowing blood, but at least I have the option.

I can relate!
We have 3. Was 4, but one of the two brothers we had passed on recently. He had a good long life. And they are all experts at the flop.
All we can do is love them, and, of course, care for their house

I'll really get helping as soon as possible
Pat










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[Mick]

Actually, there are ways to fix these sorts of troubles, as well as the top speed. A mix of .air file and aircraft.cfg entries.

Well, that's pretty much what we figured, but neither of us knows how! We're just full of vague generalities but rather empty of specific knowledge. I've learned more than I ever knew before just from your posts. David knows a lot more than I do from his experience building models, but he's almost a novice with helicopters.

One thing David should have done is set the static angle of the main rotor forward, not aft, and then adjust the .air file settings to match...

I will let him know if he hasn't read it here already (Maybe he hasn't - life is pressing him for time even more than me these days.)

I can relate! We have 3. Was 4, but one of the two brothers we had passed on recently. He had a good long life. And they are all experts at the flop.

You have my sympathy for your loss. I'm down to my last cat now. We lost Rowdy's co-kitty a couple years ago to cancer. I'd love to adopt more but I'm in my seventies and lack suitable godparents, so I don't feel right about adopting a pet that I would almost certainly leave an orphan.[/QUOTE]

All we can do is love them, and, of course, care for their house

Yep. As for caring for their house, Rowdy is a firm believer in the old adage, "Dogs have masters; cats have staff."

I'll really get helping as soon as possible

I really appreciate that and I'm sure David does too, or will when he sees your comment. There is absolutely no rush. We have a lot to do before we can seriously delve into the flight model. The H-37 VC is just started, the VC panel isn't finished and the VC isn't painted. The HR2S VC isn't even started yet. The 2D panels still need work. We still need a few slightly different versions of both the H-37 and HR2S 3D models.And work is barely moving along on these things because both of us have come into times when real life matters have reduced out hobby time to almost nothing for at least a little while yet. So we appreciate your willingness to help and we gratefully accept, but there is absolutely no rush. If you were ready to jump in right now, we'd probably have to keep you waiting around.

 

[Bushi]

a little graphic for illustration

Okay, first, I agree with Huub that the simviation Wessex is a very nice helicopter to fly. Stable, no funky issues, even when flying with a rather well used twist grip joystick that sometimes gets squirrelly with the rotation axis!

I would download it, fly it a bit, see what you think of it's dynamics, and what you could do to adapt some of these to your project as far as flying stability is concerned.

As for the rotor mast angle. Now.. I could be so far off here in my thinking, but it seems to me that FS doesn't actually care WHAT angle the fuselage is modeled at when it comes to flight characteristics. It seems to be HEAVILY if not solely reliant on what that rotor disc angle is. In the hover.. it wants that disc LEVEL, and in forward flight, it want's it canted forward.. the more it is canted.. the faster you are going. Just like the real aircraft. Hence why you see all these canted forward rotors in real life.. and why they all are tail down in the hover as a result.

My Jet Ranger unfortunately has a mast that is vertical to the fuselage, meaning that in the hover, the fuse is level, as is the rotor disc. so.. in forward flight, with the rotor canted forward.. so is the fuselage. The air file and dfg I'm now using has taken a bit of that nose down attitude out of it, to the point I can live with it... but I'm still convinced that the difference in angle between the rotor disc and the fuselage centerline in the model is a big factor in the heli's attitude in flight. Based on my Nemeth MD 500E wih a distinctly forward cant to the disc, and the Alphasim Chinook as well.

I've attached a couple of screenshots of my Jet Ranger on floats (so I could use the upper float structure to better illustrate the centerline of the heli) .. one showing an unedited forward cruise flight Jet Ranger, and the other in which I put the bird into a hover, (level fuselage) and added the forward tilted main rotor to the image.
The related angles to rotor disc (red), fuselage (green), and horizon (yellow), angles with and without that disc (mast to fuselage) being angled is quite apparent.

I think that playing with the rotor disc to fuselage angle will still yield a more 'livable' nose down attitude for your heli.

It's too bad there isn't a way to actually adjust this while in flight!!!!!

But hey.. I'm no modeler by far!!! I'm just basing my thoughts here on observations from flying several heli's in the sim.

And hoping that with enough input from members here, you guys can put something together that you will be VERY proud of!

Cheers
Dave

 

[Mick]

Thanks for your comments.

We've set the flight model aside for a bit. David is busy dealing with a serious illness in his family and I've been battered with demands on my time and attention, not to mention that flight modeling is far from my areas of expertise.

For the tie being we're back to a flight model that David apparently derived from the stock Robinson. With it the S-56 flies like an R-22, which is not bad but probably not much like an S-56. The turning tendency I grumbled about with the modified S-55 flight model is gone, and adjusting the rotor seems to have helped quite a bit (but still not enough) with the excessive forward pitch attitude in forward flight. Aside from that, the most obvious thing is that it has the top speed of an R-22, which is about half the speed of the S-56, which was a helicopter world speed record holder.

Anyway, for now, as time allows (not much these days) we will work on finishing up the VCs and the variants of the visual models. We have a LOT of work to do in those areas and not much hobby time to do it, so it will keep us plenty busy until Pat is healed up and able to help with the flight model.

We have learned a lot from the comments you and others have made here and we really appreciate them, but we are still novices with helicopters and especially with their flight models.