Throttle "Governor"

baronpilot

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OK, I will admit it: Once I start thinking about a project I can't stop until I am comfortable with the end result.

I really like the Helicycle and think the turbine is great, but the way the throttle is controlled scares me. Here is why:

On most helicopters you manually twist the throttle control and a rod pushes/pulls the throttle assembly at the fuel controller. Before you pull collective you get the engine/rotor up to speed by twisting until you are there. To help maintain RPM when pulling the collective some helicopters use a mechanical correlator that advances the throttle even further to help maintain the desired RPM, but you still have to tweak it a bit with some minor twisting.

On other helicopters you have a governor. You still set the throttle where you want it and the governor electronically "maintains" that throttle setting once it is set. If the governor fails you simply have to maintain the throttle setting yourself.

Both of the above systems still use mechanical linkages and are bullet proof.

Now, to the Helicycle. The pilot's operation is the same; however, the actual system is very different. The Helicycle uses an electronic throttle control, not a "governor." Here is the problem I see: When you twist the throttle you are actually adjusting a potentiometer on the end of the collective stick. That signal is then sent through wires to a computer that then sends power to a servo that runs the throttle. That sounds great except for one thing - it has too many points of failure and no backup. Stan tackled one obstacle by having an isolated automatic backup power source, but that is only part of the problem. If the potentiometer, wiring, computer, or servo fail you lose the ability to control the engine and that does not sit well with me.

It seems to me that this system should either be converted to a mechanical throttle and corellator or mechanical throttle and electronic governor. What it has now is not even good enough for a car IMO. I have repaired too many GM SUV's with failed fly-by-wire throttle controls to be in the air with nearly the same system.
 
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James

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Locally, a female pilot and her co-pilot were killed in an army heli, I forgot what type. Part of the FADAC system or the fly by wire failed rendering the machine uncontrollable. Her husband is sueing the military and the makers of the FADAC system for millions of dollars.
 

StanFoster

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Todd- The Helicycle fleet has way over 5000 hours now, and I don't know of any throttle issues. I love the way mine works, and the only time its used is when I go from idle to flight rpm's. This throttle issue brought up by you has never been spoken to me from experienced Helicycle pilots. It works great! Stan
 

hillberg

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Made a manual override & electric governor for the jet exec works very well. works on any T62 T32 with the torque moter controled FCU-:Cry:
 

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baronpilot

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Made a manual override & electric governor for the jet exec works very well. works on any T62 T32 with the torque moter controled FCU-:Cry:

Talk to me Goose... Are you saying that the throttle can be manually controlled regardless of whether the governor is operational? In other words: Can I control the throttle manually without any electrical help if needed? If so, we need to talk.

And Stan, I agree the Helicycle is the premier ship and the most reliable. Heck, the fact that I can only point out a few things that concern me says wonders for the ship. I don't think it is 100% accurate to say they never had a problem, though. Quite a few flamed out before the RF interference was figured out. I just want the most reliable system that can be made to work within reason and maybe that is what already is installed :)
 

baronpilot

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Guys,

Just so you know, I am not knocking this machine - I own one, so keep that in mind. My whole-home generator operates exactly the same way. The engine runs at at constant RPM and the changing electrical load required makes the throttle control respond as needed to maintain the proper speed. My "throttle control" computer failed in the generator 3 weeks after I installed the system. GE sent a repairman out and he said they fail once in a while. I can do without electricity in my home for a few hours, but losing power in the helicopter for even a few seconds does not work.

My suggestion would be this (and maybe this is how the Exec above works):

Mechanical linkages from the throttle handle to the fuel controller arm (not a POT that send a signal to a computer that drives a servo) to establish flight RPM of 61,500 (or whatever the speed is.) A button is then pressed to engage the governor which is pre-programmed to hold flight RPM. This would be a computer driving a servo motor that uses an additional linkage also attached to the fuel control arm that would advance the throttle up as required. Now, if the governor failed, you could simply twist the throttle to assume this function as you have a mechanical connection. Currently, you have no direct control over the throttle and no electronic backup and if any part of the throttle control system fails the whole system fails. This really would be an easy thing to produce. The only real challenge is in the design of the fuel controller arm. It would need to have two seperate arms riding on the same shaft or the governor would simply push on a tab on the existing arm as needed.
 

StanFoster

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Todd and Don- I am listenibg to something that never bothered me. Even though my throttle is working fine, that didn't stop me from doing mods to other things that were working! I just need a scenario throwed at me for the benefit of having a manual over ride. I may answer my own question partially by saying.......if the turbines rpm started running away, and the overspeed circuitry failed and the throttle alsio. Very unlikely but still posisible. I could close the fuel control arm manually. Ok, if the actuater motor went haywire, unlikely but possible, I could override that. I am listening, send me more what if scenarios. Stan
 

baronpilot

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Stan,

The overspeed does not bother me as much. You can kill the fuel and end that problem right away with an auto, but with a mechanical system you could override that also .

Here is the real problem:

As your machine now sits you have no direct control over the throttle. You only have the ability to tell a computer through the use of a POT, wires, computer, and servo to maintain the RPM you want. If any of those items fail you have no choice but to enter an autorotation. Would it not be much better to be able to control the throttle manually and let the computer fine tune the inputs knowing that if the computer or it's accessories failed you could still land the helicopter under full control? I would not be as concerned if the ship had redundant POTS, computers, and servo's, but it does not. In a GM car the gas pedal has two pots and the computer compares their output before commanding the throttle and they still have problems.

I think that in the excitment of making the turbine work they missed this very important point. They did a fabulous job with the transmissions and the rest of it. I just want to improve what I feel is the weakest link.
 

PW_Plack

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In fly-by-wire flight cyclic controls, the big guys now aim for triple-redundancy. I don't think the concern is unreasonable.

If I was looking for a backup to the electronic system, I might even look to a mechanical governor with a slightly wider "dead band" (to use the thermostat term) bracketing the more precise electronic regulation. If this mechanical governor was preset for flight speed, and was either engaged or not but not otherwise adjustable, I think you could greatly simplify any potential issues of conflict between the two systems.

If the manual throttle control (or is it just a speed control setting for the governor?) uses a robust pot, optical encoder, or other component, it should be pretty solid. But RFI could raise its head even in well-engineered systems, because the variables of owner modifications are sometimes unpredictable.
 

baronpilot

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PW,

I am not sure as I am new to the Helicycle, but I assume the pot simply varies a resistance that the computer then uses to move the servo and set the RPM. From that point the computer monitors the RPM and moves the servo as needed to mainatin the RPM.

I am not worried about RF because I believe that has been properly addressed. What I am worried about is the failure of a a single piece of electronic equipment that can take your flame away.

I'm not sure if you could easily build a "manual" governor and an electronic one since the range of RPM is very tight. You have only roughly 30 RPM on the rotor and 1000 RPM on the engine to play with.
 

HobbyCAD

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Stan, I was not aware there is a potentiometer at the end of your collective twist grip. Could you post a picture of it, as well as where it is wired to? I presume it goes to the Trim Speed connections G, H and J on your ESD5200 governor box. Is it able to select any turbine RPM from idle to max? How do you select max and min RPM range of the settings, can you overspeed it by twisting open too much? I suppose the governed RPM is then where this potentiometer is set at?

Regards,

Francois
 

HobbyCAD

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Todd, the T-62 range of turbines have 2 types of FCU's available. The most well known version is the electrically controlled governor FCU type, the type with the large torque motor on it. Then there is also the mechanically controlled governor FCU type, that is mechanically preset. There are a few of such installations in service, where the guys have tapped into that mechanical preset adjustment, and made the RPM selection a pure mechanical control. This is what I prefer, and seemingly what you are after.

I used to own 3 T62-32's, I salvaged them out of Alturdyne GPU's. The were exactly the common -32's most guy's have, but instead of the electric torque motor, it was the mechanical governor type. I've never again seen this configuration on -32's, only on -27's and -16B's. My -32's ran great in this configuration, I had a single ground idle/flight idle mechanical selector, and a second governed RPM range mechanical selector. Worked like a charm, no electronics needed to control it, once it was up and running.

I've attached some pictures.
 

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StanFoster

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Francois- I can control precisely the turbine rpm between idle which is around. 48000 to flight rpm which is 61500 rpm. It won't overspeed. I was just flying 2 hours ago, and the engine tach holds very closely to 61500. It may vary 100 rpm. You cannot feel or hear any rpm changesm. When hovering in ground effect, rapid up collective sees the governor reacting very quickly. I don't have my wiring diagram with me, but the terminals you mentioned sound correct from my memory. I will look next time I go to my shop and post back here. Stan
 

pancho

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That should be a fairly easy fix. A flex cable set to "follow" the computer controlled servo ought to be fairly easy to set up. I do think that arrangement would also make me a tad uncomfortable. I've had car computers quit on me and when they do it is sudden and as far as I can tell unpredictable. The problem with a helicopter would seem to be that when the ol p'uter konks out, you could just as easily have a runaway as a dead engine. Both would be potentially disastrous. As far as reliability of the Helicycle system goes, they may be ok, but I'd sure like to see closer to 5000 THOUSAND hours on the fleet. Heck at last tally I have substantially over half of the 5000 hours in my own logbook and I'm fairly inexperienced by professional standards.
 

baronpilot

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Please disregard my post. I will be leaving the throttle as it was originally designed.
 

hillberg

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The Solar,T62T32 has 3 types of FCUs 1- Fly weight hydro mechanical,2-Electrical Hydro mechanical & 3- Digital control Head.common problems for #2 are spring & torque moter failure along with RF spikes, the Didigital has too much going on and will shut down if rates & limits don't match onboard logrithims ( Ask the guys with the turbine Luscum project)# 1 is great but hard to get #2 is all over. #3 forget it.
An engine slaved to an electrical system is a problem if over rocks & trees, (Battery,Generator short,Broke wire,dead bus,)A pilot needs direct control of power when he needs to get out of trouble.
Had good friends die from FADEC ( Found Another Dead Engine Control.)
 

HobbyCAD

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The Solar T62-32 has 3 types of FCU's. 1- Fly weight hydro mechanical, 2- Electrical Hydro mechanical & 3- Digital Control Head.

#1 is great but hard to get. #2 is all over. #3, forget it.

Yup Don, mine was #1, the mechanical unit using the bobweights and fuel pressure to regulate RPM.
 

StanFoster

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Todd- .... Your questioning the throttle has me now thinking about it. I love the way mine has been working, but admit you bring up a valid point. Don and Francois, you two know far more about this than I ever will. Let's say I am flying along and my engine goes to idle..........48000 rpm instead of 61500. I need a mechanical link to my fuel control arm and need to operate it fast. It looks to me that it should be on the collective as I need my hand there during this incident. This mechanical overide has to allow the fuel control arm to freely move when its working properly, yet be over riden should the governor fail. I am ignorant how to go about this in a way I could easily modify my own system. The throttle part never concerned me, but I have thought that the governor just has to be trusted completely or an auto will result. I could see having a cable attached to the throttle grip that could move the fuel control arm but would have to have a way to instantly engage it to overide the governor, but be freely floating while the governor is working fine. Any thoughts? Can one even control the power precisely enough as that fuel control lever moves very little. Maybe I have been flying blissfully and ignorantly. I do fly like the governor or anything else could quit anytime, simply because anything mechanical can quit! Stan
 

HobbyCAD

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Stan, what you are referring to, is already implemented in modern FADEC helicopter engines. It's called freeze mode. If the FADEC misses a beat, or you have a total power failure, the engine throttle mechanically moves to 75% power. Might not be enough to pull you into a hover, but it is enough to do a running landing.

I would place your little camera (or a GoPro, I use 3 for our test flights) looking at your throttle arm, that one that hardly moves, but when it does, it moves very rapidly. See where it is at normal operations, and figure out a way how to get it to lock there, in case of an emergency.

I'm thinking of a horizontal plate with a V cut into it. The V open end is slightly wider than the full travel of the arm. Position the plate with the middle of the V at the point of 75% power, just next to the arm. Hinge the one side, mount a pull wire on the other. If you pull on the wire, the V moving over into the arm arc will force the throttle arm to move into the centre of the V groove, overriding the drive force keeping it anywhere else. This will place the throttle locked at 75%. Get my idea?
 

StanFoster

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Francois- Your explanation is extremely clear, and thanks for that. I see you are just saying over riding it going to idle, and your V notch idea seems brilliantly simple. A simple push pull choke wire could apply power back even more than 75% possibly. I do have two micro switches on my fuel control arm that shows when I am asking almost 100% by turning on a yellow light, and a end micro switch shows when I am at 100 %. Thanks for giving me something to chew on. I like your idea of immediately getting the power applied, but not trying to fine control it. Stan
 
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