Helicopter Autorotation

[Brianl 2]

I've searched for an answer/suggestion around the forums without success and am hoping for help here.

The general "forum" opinion is that in flight simulation, rotay wing modelling has always fallen far short of fixed wing. I fly a Cabri G2 in real life. I find the MP Design Studio version for P3D works very well indeed and compares to the real thing nicely, except for autorotations. We all know what they're about. The engine fails, lift can't counter gravity, nose drops, main rotor slows down when collective pitch is increased, etc.

Real recovery needs quick pull-back on the cyclic followed by immediate full-down collective then careful main rotor RPM control with collective and a final flare to reduce the forward speed and collective up to slow verical speed to zero.

This process can be started OK in the sim by pulling back on the cyclic and flooring the collective. But the engine has not failed, as it would have done in reality. So I would need to cut engine power completely to simulate the cause of an autorotation. How? And to reduce main rotor RPM during the rapid descent I would need to increase collective pitch, but if I did this with the engine still running and the governor engaged, I would get an increase in lift! So the autorotation process has failed in the sim. And so it goes on.

The consencus amongst flight simmers is that sims don't model autorotation. I think that's true because the flight dynamics involved aren't what's needed in normal flying. I also think that there's scope for getting P3D and my Cabri G2 to behave as expected during an autorotation by changing settings that relate to governor, collective pitch, independent throttle control and possibly others. I've never believed in reinventing the wheel so at this stage I'm wondering if anyone out there has already studied this, especially with P3D and the Cabri G2.

I'd be delighted with any ideas that can be offered. I intend to persuade my setup to produce realistic conditions that lead to autorotation and respond realistically to the right sequence of corrective actions. I'm sure I could do this much quicker with your help than on my own by trial and error.

All the best,

Brian

[jcomm 5,929]

Helis in MS FS .... Hmmm, sorry, but simply forget it...

Well, there's an exception, but afaik not available for p3d yet - DODOSIM Bell 206. That was indeed a reference, in times of fs9 / fsx.

My best suggestion is... Want helis, go DCS World UH-1H...

[jabloomf1230 2,445]

I agree with jcomm about DCS, but lacking a DodoSim helicopter for P3d, I would go with the Milviz  UH-1 Redux.

[Chock 17,769]

As far as I'm aware, the light at the end of this particular tunnel may be the Dodosim JetRanger, which the developers did say they were going to make compatible with P3D. Other than that, it's a case of looking at different sims specifically aimed at chopper operations for that kind of thing. And there are a few worth noting...

If you can find it, 1C made a very good sim of operations with the UH-1 Huey in Vietnam. It's a bit flaky in places but if you stick with it, it does model chopper operations pretty well and has a good mission which simulates the Airborne operation which is the basis of the Book/Film, We Were Soldiers. Another one worth a look is Bohemia Interactive's Take on Helicopters, which used to be sold at simmarket but is now available direct from them and is pretty cheap now (£11.99 for the game and £5.99 for the MiL-24 Hind expansion). It's not 100 percent realistic, but it is kind of fun in terms of its first-person perspective which allows you to genuinely walk around your chopper and perform maintenance on it. Then of course there is the Huey in DCS World, which is truly excellent.

Take on Helicopters Vid on my youtube channel from way back when it was in beta:

 

Edited May 4, 2020 by Chock

[BlueStar 323]

I flew high inertia rotor systems in the military and have never found a desktop flight simulator that I could fly. They just didn't seem realistic to me.  High inertia rotor system autorotations are not flown like the OP said, they are two different animals.  

I could be wrong since I only have 3,000 hours in helicopters including the UH-1, AH-1, OH-58 and CH-54. 

[HighBypass 2,339]

BlueStar - I read somewhere (don't we all? ) that with a high inertia rotor system like a JetRanger, and thus presumably the AH-1, and maybe the UH-1, if the pilot managed an autorotation conservatively then he could pick the machine up again, pedal turn 180 dgrees and set it back down before the rotor speed decayed low enough to be unusable? Was there some ebellishment of the facts or is that close enough to be real?

If I can go off at a slight tangent - would accurate modelling of gyrocopters be similarly afflicted or do they fly sufficiently different between helis and planes?

[Chock 17,769]

34 minutes ago, BlueStar said:

they are two different animals.

Well there is that, but then again, some choppers handle differently from others as you know. I was talking to one of the guys who flies the UK-registered UH-1D Huey and the Hughes OH-6 Loach - the later of which was actually shot down and recovered when serving in Vietnam during the war. He told me he much preferred flying the Iroquois, which he said was 'ponderous' on the controls compared to the Cayuse, which he said was extremely twitchy, and that I can well believe from the size of the thing.

Those OH-6s are really small but they don't look particularly resistant to gunfire, a fact confirmed by the one I went in which had been shot down in Vietnam. So I can't say I'd have fancied being in any of them under fire whether that led to an autorotation or not, plexiglass and aluminium is not known for its stopping power against bullets, and every helicopter I've ever been on smelled so much of jet fuel when you got within a hundred yards of it that it felt like the thing was ready to burst into flames just sitting there. 🤣

You have my admiration sir.

Oh and here's a fun fact about the Hughes OH-6 Cayuse: When it was being developed and Hughes were looking for materials to help reduce vibration with their acoustic qualities, but still be reasonably light and tough, the material they ended up developing found another use owing to its acoustic properties - it's what they ended up making the bowl back of Ovation Acoustic guitars from in the 1970s. So if you like all those ELO and Supertramp etc tunes from around that time, then you can thank Hughes Helicopters for the guitar sounds.

Edited May 4, 2020 by Chock

[HighBypass 2,339]

Alan, that wouldn't be Neil Airey would it? At the time I met him he was, possibly still is the chief pilot for Huey 509 and a pilot for the NW Air Ambulance - I had a good chat with him and a guided tour of the EC-135 he'd dropped into the village to attend to a 999 call. (It was determined that the patient was going to travel to the hospital via terrestrial means, hence the tour whilst we were waiting for the paramedics to finish up).

[Chock 17,769]

1 minute ago, HighBypass said:

Alan, that wouldn't be Neil Airey would it?

I'm afraid I did not get the guy's name at the time, although I daresay it probably would have been that guy because he did mention being one of the Air Ambulance pilots. He was very nice to talk to and enthusiastic about showing off the little Loach chopper to me in spite of him preferring the Huey.

[KenG 492]

56 minutes ago, BlueStar said:

I could be wrong since I only have 3,000 hours in helicopters including the UH-1, AH-1, OH-58 and CH-54. 

Agreed helos in real life and helos in FS/P3D makes me think ACES just missed the boat completely. Heck they were on a different boat going to a different destination.  

I am also a rated helo pilot from back in the day and I cannot fly a helo in FS. I attempted to autorotate the Jet Ranger, a helo I was rated in, and watched in bemusement as the aircraft entered into a vertical spin midair then just sat there spinning nose over tail in complete defiance of gravity. The bigger the Helo gets the worse the FD is in FS. I also have some S70 time and the hawk in P3D, IMHO, is a joke. 

Maybe I have lost my hover button after all these years, but I suspect it is more like the sim is just that far off of reality. 

Brave Rifles. From when the ACR still had a RAS

Edited May 4, 2020 by KenG

[BlueStar 323]

6 hours ago, HighBypass said:

BlueStar - I read somewhere (don't we all? ) that with a high inertia rotor system like a JetRanger, and thus presumably the AH-1, and maybe the UH-1, if the pilot managed an autorotation conservatively then he could pick the machine up again, pedal turn 180 dgrees and set it back down before the rotor speed decayed low enough to be unusable? Was there some ebellishment of the facts or is that close enough to be real?

If I can go off at a slight tangent - would accurate modelling of gyrocopters be similarly afflicted or do they fly sufficiently different between helis and planes?

The CH-54 when not loaded could do an autorotation  then picked up and turned.  The UH-1, AH-1Gs and OH-58s were all done when the autorotation was completed.  The UH-1/AH-1s had a lot more inertia in the rotor system than the OH-58.  It may not seem like it, but the UH-1H is three times bigger than the OH-58.

 

[Brianl 2]

I didn't expect such a large response to my query. Neither did I expect an almost complete disregard of my question. Nor  a complete absence of helpful suggestions. I'm more than a bit surprised.

Well, if you lot want to chatter about other things and depart from my original subject matter let me join in. Your responses contained lots of comments about the tiny number of helis that work in sims. You all seem to reckon that sim heli flying is not realistic. Wrong. I've flown several in FS & P3D and a couple have  been very lifelike, i.e. the Schweizer 300CBI and the Guimble Cabri G2. I've flown them both at a nearby airfield for the past 4 years and FS & P3D do them justice - apart from autorotation.

I'm still hoping for a helpful response or two - Please.

Brian

[HighBypass 2,339]

I consider myself chastised, Brian. My apologies. 

 

Re-reading your original post, you say that the Cabri G2 is quite realistic and you can enter into an autorotation initially. I guess the "easy" way for an autorotation would be to turn off the engine or fail it. Have you tried that to see if the one way ticket autorotation works to your satifaction?

[Wells 5]

From what I can tell, if the 1400 sections are in the air file, then autorotations are possible, but no other helicopter things work, like tail rotor translation, torque vs collective, mast tilt, etc.  If the 1400 sections are absent, and the aircraft config file contains all the updated ( since FSX:A ) entries, then everything except autorotations will work.  So, either way, you are screwed, unless you have external code, such as HTR or something else ( dodosim? ).  Unlike aircraft, the config does not overwrite the air file, if the 1400 sections are present.

[Brianl 2]

20 hours ago, HighBypass said:

I consider myself chastised, Brian. My apologies. 

 

Re-reading your original post, you say that the Cabri G2 is quite realistic and you can enter into an autorotation initially. I guess the "easy" way for an autorotation would be to turn off the engine or fail it. Have you tried that to see if the one way ticket autorotation works to your satifaction?

Yes I've tried that by pressing F1 which should cut the engine - it doesn't. But I can start "autorotation" OK like we do in the real aircraft by flooring the collective, that's not where the problem is. In a real auto the main rotor revs increase with vertical speed. to keep NR in the green you have to raise the collective; if the engine is still running that also repowers the main rotor and the autorotation stops. Same thing happens in the final stage of correction where you raise the collective to setle the aircraft on the ground with the VSI showing zero; if the engine is still running you get engine-induced lift which wouldn't  happen in real life.

Thanks for trying to help HighBypass.