David Gladwin

Craig, I was out flying my dual gyro equipped BobCat yesterday, one on yaw axis, the other on roll in bumpy conditions, That model is rock solid now and produces beautifully clean stops on the 4 point roll etc AND even helps keep loops more accurate, corrections to turbulence induced displacemens are immediate. Several of my jets have this set up and all are being progessivly modded, it makes the flying just SO much smoother.

Yesterday I was using the Futaba 352 but I also use the ACT Fuzzy Pro which works to perfection and has stick fade out meaning that the handling is almost totally unaffected, with perhaps just a tad more aileron travel required.

120 degree gyro set ups MAY work very well on some aircraft but individual gyros on individual functions give me what I'm looking for, MUCH smoother flying, particularly in bumpy conditions, whilst retaining normal handling.

We now await, with baited breath, a demo by DAVO 58 of any of his aircraft in bumpy conditions, I really want to see how he does it !! I need to know as we may then have a solutuion to PIOs, ie pilots trying to correct deviations and getting it all out of synch and making things much worse !)

Regards, David Gladwin.

PS For those interested I did an article in RCJI about a year ago (Feb/March 2008) expaining the workings of both flywheel and solid state gyros and their application in models.

Craig B.

Good to hear David. I am certainly sold on the virtues of gyros, and I think anyone into scale aircraft or precision flying will eventually be to.

To clarify, you use the ACT fuzzy pro SMM, yes?

I tested my F16 with a 351 on the ailerons a couple of weeks ago. Immediately after I heard the click of the gain switch she flew on rails. A few low passes at half throttle revealed the gyro correcting the roll oscillations...you could see it working at 80% gain, but at 90% it was so smooth it was hard to pick. The only thing left was a slight yaw oscillation which was so minor I probably won't bother with it. Time to upgrade the whole fleet! Awesome stuff!

With your 352 on your bobcat....do you have each aileron on a separate channel so the gyro was only affecting one aileron, or are your ailerons y-leaded so the gyro could influence both ailerons?

Great thread guys!

Regards,

Craig.

Guillermo Ibanez

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Hi Guys:

Very interesting thread

I have flown my first Jet (Skymaster F-16 1/8 with flapperons and elevators - set up like Craig's one but with CG in 143 mm unlike Craig's), 22 times since February 9 to August 10 2.008 when it crashed due to a sudden low battery voltage (4.3 volts) during a steep turn with full tanks at low altitude, and I can confirm all that you are discussing in this international thread about flying in bumpy air. (Tail wiggle, very difficult landings with cross wind, nose an main wheels supports broken because landing out of the runway, etc.)

Taking in account the high cost I paid to recover my Jet, I will not doubt in installing all the accesories for keeping alive my investment, so I ordered Duralite Batteries with powerbox, and I am going to install two ACT Fuzzy Pro SMM Gyros, one for ailerons and one for rudder/nose wheel. (My nose wheel is in a sepparate channel and is mixed with the rudder channel, just to adjust the wheel center line with the trim without affecting the rudder trim). I also am going to set up the CG in 175 mm as Craig's said. (Any suggestion about these set up for my new maiden flight will be welcome)

My question about the tilted Gyro is: How does this arrangement control the nose wheel to keep a straigh line during take off or landing if it controls yaw with ailerons? Nobody have made this question in this thread.

These is my first Jet and I have no experience with Gyros, so I would like anyone help in set up once I begin to set again my model (New fuse, rebuilt turbine, etc.).

Although reading all these thread have helped me to understand about Gyros, I will appreciate anyone's help.

Craig:

I have not read nothing about the servos coupled to Gyros. Do I need like helicopters a special servos for Gyros? I mean very fast servos like those that have a speed less than 0,1 sec?. My ailerons servos are Futaba 9351 digital servos with 0,16 sec / 60Ā° at 4.8 V and 0,13 sec/60Ā° at 6.0 V and the Rudder Servo is a Futaba 3102 with 0,25 sec/60Ā° at 4.8 V and 0,20 sec/60Ā° at 6.0 V. (My Power Box Duralite 40/16 Evolution regulates at 5.90 V).

Chad:

I also have not read nothing about voltage with Gyros. All Futaba Gyros are set for 4.8 Volts. My set up with the Power Box is in 5.90 volts. Am I going to have problems with the ACT Fuzzy Pro SMM Gyro? (ACT Web page is in German and I can read something like: "Betriebsspannung 3,0...8 Volt)

Guillermo

SinCityJets

No voltage problems with the Fuzzy. The voltage range is 3.3 - 9 volts.

As far as your question about the tilted gyro set-up controlling your nose wheel; it won't. When Jesus refers to controlling yaw, he is referring to in the air, and it does it with ailerons only. It is a unique set-up and I have not tried it. Personally, I am going to have to side with David Gladwin. Rather than let one gyro control two planes half-ass, I would rather use two gyros to control them both perfectly.

I do think it is a creative idea and probably works quite well considering.

Also, I have the SMM manual sheet if you send me your email. It is in three languages.

David Gladwin

Craig, Each aileron is on a separate channel, the 352 processes each channel. One of my AW Hawks has a Futaba 352, the other a Fuzzy pro as recommended to me by Thommy Gleissner, (works fine on the 5.7 v from the Weatronic DR. My Bobcat XL also has a Futaba 352.

You don't need ultra fast servos to work with gyros, just accurate digital ones for good results.

I doubt I will ever build another swept wing jet without aileron gyro(s) installed almost all of my jets have a gyro on nosewheel steerring and rudder, all JR piezos.

Guillermo : an expensive jet = TWO receiver batteries !!!!

Setting up the gyro is easy, you start with very LOW gain, increase until it overcontrols then back off a shade, thats really all there is to it, but take a look at the RCJI article. Its a bit more complicated if using attitude hold (only heli pilots call it heading hold, ) and its important you know how or rather, when, to use the Tx aileron trim.

Regards, David Gladwin.

shonny

Ah, slight problem there when mind is missing!

Guillermo Ibanez

My Feedback: (1)

Thanks Chad for your help.

I am going to have to side with David Gladwin too. Two Gyros. One for Rudder/Nose Wheel and the other for Ailerons.

Chad, my mail is: [email protected]

I would appreciate if you can send me the ACT Fuzzy manual.

David:

Thanks for yor help.

My new set up use a Power Box with two redundant Duralite Li-Ion 4.300 mAh 4 cells 7.2 V receiver batteries and 7.2 V 4.300 mAh 4 cells Duralite battery for ECU.

I was wondering that heading hold was able to keep heading so in a landing procedure, once aligned with runway and both Gyros in Heading Hold mode, the model path was directly to the runway center line no matter bumpy (cross wind gust) conditions, but you said that the mode is no heading hold but attitude hold. Please clarify me this concept.

About Craig's and many other comments about Davo580, I would add that as Craig said, Gyros can compensate very fast, any slight changes in attitude (faster than our brain can do), remember that some Gyros use PID (Proportioal, Integral Derivative algorithms). That mean that Gyro response can anticipate any changes in attitude, faster than one can. Real Pilots use autopilots to fly Jets and even to land and when landing conditions are aggresive, autopilots do all the job ant the pilots just take control before wheels touch down. Now, we are not in the cockpit, and although unlike autopilots, Gyros don' fly the model, they just make minor corrections, is more difficult to us to anticipate any change in attitude without putting our investment is high risk. (I already did and payed for it).

Dear Folks, as many of us, my intention is to enjoy my jet with extreme precaution to protect my investment. I don't want deffinitely use "mind over thumbs". I don't want to show to others or to the public my skills. I want to fly in a safe manner as real pilots do. I am sure that Airlines don't pay their pilots to show their skills, but to bring the passegers and the Jet safe to the ground.

I have seen many pilots crash their Jets to a total loss for flying in an agressive fashion and that is not my intention. I prefer to fly in a very conservative fashion and using all the electronics available on the market to return home with my jet in one piece.

Once I read the ACT Fuzzy instructions, I will bother all of you with new questions.

Guillermo

Gonzalo38

Anybody knows were to download the instructions of the Fuzzy Pro ? I would like to take a look at them before deciding to purchase one.

causeitflies

With all the work the servos do under the control of the gyro, do you guys notice more power consumption compared with no gyro?
Any effect on servo life?

Guillermo Ibanez

My Feedback: (1)

Gonzalo:

Chad is going to send me the Fuzzy instructions by mail.

Please post your E-Mail. Maybe Chad will send them to you too. If not, I can send them once received.

Guillermo

jseppanen

ACT Fuzzy SMM manual, in english pages 5-7; http://www.acteurope.de/intanlfuzzySMM.pdf

ACT Fuzzy Pro (no external smm sensor) manual, in english pages 7-9; http://www.acteurope.de/intanlfuzzypro3.pdf

Regards,

Janne

Gordon W

Excellent thread!

Here: http://www.acteurope.de/html/download.html

Gordon

Guillermo Ibanez

My Feedback: (1)

Thanks Gordon.

Guys:

Now I am confused:

I have read both manuals and looks almost the same.

Which is the best Gyro? ACT Fuzzy or ACT Fuzzy Pro? Differences? Advantages? One is piezo and the other SMM ?

Chad:

Please your help.

Guillermo

Craig B.

Hi Guillermo,

My aileron servos are jr 8411...they work well and are certainly fast enough. I think that your rudder servo might be a bit slow but I doubt you will need a gyro on the nosewheel steering as the steering is very docile and ground handling very good, but it certainly would not hurt either.

The smm fuzzy gyro is better....the sensor is better and does not suffer from temperature drift like piezo gyros. My futuba 351 is operating on a powerbox at 5.9 volts and is rated to cope with that ( I think 6 volts was specified maximum voltage

Hope that helps.

David, thanks for the info. I was under the impression that the 352 was dual axis with one channel dedicated to each axis, while the 351 was single axis, dual channel. Can you please clarify the nature of the 352?

Thanks.

Regards,

Craig.

SinCityJets

There you go folks! Great links Janne!

SinCityJets

Guillermo,

The Fuzzy SMM is their top of the line gyro, and is the only one I import. As has already been stated, it's external SMM sensor is not prone to a lot of factors standard piezo gyros are, with temperature drift being the most significant. Aside from that, it has a better response and more accurate sensor.

Chad

David Gladwin

In haste but a few points;

The 352 gyro processes TWO channels on a SINGLE axis. I use mine on the roll, longitudanal axis.

Servo life. One of my BobCats has 250 flights on it. Used a JR gyro and 9411 servos on rudders since day one, 7 years ago, servos still behave perfectly.

Fuzzy pro: It uses a very good professional British Aerospace sensor, top equipment. I believe my BMW ASC also uses it.

Heading hold. These gyros were first designed for helis and have the ability to hold a constant heading in the hover as hovering heading is a YAW function on a heli. On fixed wing heading hold is a ROLL function and the autopilot on real jets is slaved to the compass . The A/c corrects its heading by ROLL inputs (so does a heli in forward flight. )

Using the hold function on a jet means that on whichever axis you have the gyro it will resolve angular displacement (velocity times time) and then remove that displacement to return it to its position or attitude before the displacement. ( Boeing used to use a simiilar system called CWS). It is POSSIBLE that if you EXACTLY line up a model on the centre line and slect HOLD on rudder and aileron you might stay on centerline. Winds are never exactly constant so I doubt it would work in practice ! You should try it !

Remember tho. that in HOLD mode the model will still respond to stick movements, and the HOLD function only works when the stick is at neutral (which is why you must trim in normal mode.)

Morning gardening beckons, (it will be too hot this afternoon, plus 34 C !) but hope this helps. I will get back if you need further info.

Regards,

David.

Couch Potato

Is this the gyro you are using or an older now obsolete model ?
The only Futaba 352 I can track down is GYA352, a dual axis one.

http://manuals.hobbico.com/fut/gya352-manual.pdf
http://alshobbies.com/shop/lookupsto...?pc=3240&Desc=

I found the article Mr Gladwin authored/referred to:
RCJI Feb/March 2008 GasFlow Page 9...
Orange/Grey Boomerang Elan on the front cover

David Gladwin

My sincere apolgies guys, the Dual channel Futaba is the 351 not the 352 just looked at the boxes. Again my apologies for confusing you (god, am I getting THAT old ?)
Regards, David.

mick15

The 352 is a dual axis gyro David.

m


LOL you just get there before me........foiled again!!

Couch Potato

I was getting mighty confused with the Futaba gyro model numbers too.
I thought you were doing something RADICALLY clever with the DUAL axis gyro in a tilted orientation

Guillermo Ibanez

My Feedback: (1)

Craig:

Thanks for your help.

The rudder servo is only for rudder. For nose wheel I am using a Futaba Digital servo 3050 with 0,16 se/60Ā° at 6 V in a different channel mixed with rudder (Master: Rudder, Slave: Nose Wheel). The problem with the rudder servo is that there is no space to a faster Futaba servo. Which servo are you using for rudder and nose wheel?. Are both of the connected to the receiver via a Y cable?

In respect to Gyros, I want to use 2 Fuzzy SMM, one for ailerons and one for rudder/nose wheel. Although I know that they are very expensive, I want the best for my F-16 and I want to align the model with runway centerline during landing, and once at the ground, forget about steering corrections while aplying brakes. This is because in my 22 fligths, my F-16 landed at 50+ mph (very fast) I think due to the models weight (24 pounds without missiles), and the runway is very dangerous. Is like an aircraft carrier, so you need to land where you should, and apply brakes inmediatly or you are going to destroy the model at the runways end. And if you land too short (close to where the runway start), you can crash your model.

Watch this video, where I landed with the brakes activated:

http://www.rcuvideos.com/video/Skyma...18-Flight-No-2

By the way: How much does your model weight? (The one with the P-80 in the center)

Guillermo

Guillermo Ibanez

My Feedback: (1)

Hi Chad:

Got it:

I will get two of these.

By the way: Your web page can handle international credit cards?

Thanks

Guillermo

Guillermo Ibanez

My Feedback: (1)

Hi David:

Real Jets Autopilot is slaved to compass in cruise flight but in landing, autopilot is salved to ILS. So it doesn't matter wind gusts, the jet is centered to the runway like a rock. Some times you can see in cross wind landings, the nose pointing in to the wind while the jet is flying laterally. That's not the case with Gyros.

Very clear your explanation about heading hold.

I will try with bot Gyros (Rudder and Ailerons) in heading hold once aligned with the runway and I will tell you the results.

Of course this will happen maybe at end January because I am still installiing all the stuffs in my new fuse.

Guillermo

David Gladwin

Hi Guillermo,

I tried to keep the anaology to fullsize jets quite basic although I have made hundreds if not thousands of coupled approaches on real jets, many terminating in Cat 111 autolands, it can get complicated. Models don't have any ils/vor, or irs track guidance, just you on the sticks controlling heading by adjusting bank angle and maybe some gyro stabilisation ! Even fullsize jets on Autoland may NOT have the nose pointing into wind when the autopilots begin the runway alignment mode !! As I said it gets involved !

Here is the text of the article I wrote for RCJI but you'll need to get the mag for the pictures etc.

Hope it helps,

Regards, David.

Gyros.,
Smoothing it out and keeping it stable !

One of the hot topics of conversation at the Jet World Masters in Northern Ireland was the use of gyros for stabilization. The use of such devices is allowed by the IJMC rules and most of the top fliers were using them either as yaw dampers, or stabilizers, or to hold attitude, particularly bank angle, when no control input was being made. Whilst opinion varied as to whether these devices should be allowed in a flying competition what was agreed is that modern gyros can vastly improve the smoothness, precision and accuracy of flying as proven in the superb performances displayed by many competitors at the event. Clearly, modern gyros have been developed to an exceptional degree of accuracy and reliability and, whether or not they will continue to be allowed in competition, they can greatly enhance the flying of all model aircraft, jets or otherwise. The aim of this article is, therefore, to describe modern gyros and their application but perhaps to give a better understanding some gyro theory (and a little history) will be useful.

The first working gyros were made almost 200 years ago but it was an American, Elmer Sperry, who made the first practical application of gyros in navigational instruments in the early 1900s, firstly for marine use in the gyro compass, and later for aircraft, both in flight instrumentation and in autopilots. The Sperry Gyro Company continues to this day and many modern, and not so modern, aircraft incorporate Sperry equipment.

Original gyros were mechanical devices utilizing a spinning mass or flywheel to provide the stabilization. Such a rotating mass exhibits two important properties, that of rigidity and that of precession which is a form of conservation of angular momentum. Itā€™s rigidity means that the rotating mass will stay in a fixed position unless acted upon by an external force and if such a force is applied the mass will tend to move in a direction at 90 degrees, in the direction of rotation from the point of application of the force. There are two basic forms of gyroscope dictated by the form of gimbal mounting. There is the free gyroscope, used in instruments such as aircraft artificial horizons, or attitude indicators, which have virtually total freedom of movement dependant on gimbal design, and the rate gyroscope which was, and is, used to measure rate of turn in aircraft, this latter known simply as the turn indicator and it is this latter form of gyro which has the most widespread commercial application and is the type used for model aircraft stabilization.

The adjacent diagram explains how a rate gyro works. The flywheel is mounted in a gimbal which is restrained by a system of springs. When the gyro case is turned by aircraft movement a force is applied as shown. This force , due to precession will tend to rotate the gyro axis and that twisting force, restrained by the spring system will rotate the gimbal at 90 degrees to the direction of rotation. The greater the rate of turn the greater the precessional force and the greater the deflection of the gimbal as there is more force to overcome the spring system. By connecting a pointer to the gimbal the instrument will show the direction and rate of turn. If we replace the pointer with potentiometer a voltage can be created to drive an electronic circuit which will operate the rudder servo in the opposite direction to the yaw thus damping any unrequired turn or yaw. This is the basic principle of the yaw damper used in so many swept wing jet aircraft and used originally in model aircraft to control the tail rotor in model helicopters.

The rapid advance of model helicopters soon revealed the shortcomings of the spinning mass gyro; they were somewhat imprecise, and subject to wear from the vibration present in helicopters and the development of solid state resonator gyros for commercial applications ( as distinct from the complex, highly accurate and very expensive ring laser gyros used in aircraft navigational systems) led to their use in model gyros. These Piezo electric gyros such as the JR 1000 offered vastly improved performance with a ten fold increase in sensitivity, lower current drain and, being sold state, a virtually unlimited service life.

Piezo electric gyros comprise of a cylindrical piezo electric ceramic oscillator rod on which are printed polarized electrodes When a voltage is applied to the rod it torsionally vibrates. When the rod rotates it outputs voltages in proportion to the rate of rotation as a result of Coriolis * effect. The downside of the PE gyro is that it is quite susceptible to changes in temperature but its accuracy and reliability resulted in very rapid acceptance in the model helicopter field for stabilisation of the tail and such gyro units (the actual sensors are all made by specialist companies) were, and are, made in large numbers by such companies as JR and Futaba.. The latest development of the solid state gyro (or MEMS , micro electrical mechanical system) is the silicon ring gyro from Silicon Sensing Systems, a sub division of BAe Systems which also uses Coriolis effect to detect rotation but has the added advantages of increased sensitivity, resistance to shock and vibration and very little reaction to temperature variation, in other words, perfect for model use. It is now being produced, in the millions per year, for a wide variety of applications from car stability systems to video games and camera image stabilization. This device is used in the ACT Fuzzy gyro which will be described later.

The first sold state gyros on the model scene, such as the JR 1000 were purely rate gyros which dampened the swinging of tails in helicopters but were also used on rudder and nosewheel steering on fixed wing models . Such a gyro was used with great effect on my BVM T33 which had very poor ground handling with the original landing gear (vastly improved with BVMā€™s own, excellent, landing gear units) and many tailwheel models were ā€œtamedā€ with a gyro controlling the rudder. Following the appearance of solid state rate gyros a British company, CSM , developed a gyro system, the ICG 360, which would not only detect a rate of turn but would calculate the amount of turn and apply a corrective control input to return the helicopter to the original heading. It is possible to switch between modes in flight using the gain control. This breakthrough device was extremely effective and when hovering a helicopter the heading of the machine remained absolutely solid , even when lifting off in a very strong crosswind. The device was called heading lock but heading could only be held in the hover as in forward flight the heading of a helicopter is controlled by lateral cyclic, as the ailerons of a fixed wing aircraft, and if heading hold remained active on the tail rotor the machine would be very difficult to turn as the gyro would attempt to hold the nose in a constant direction. Clearly, if used on a fixed wing aircraft a heading lock gyro cannot be used on rudder as rudder inputs would then oppose normal turning and result in large yaw angles as a result of rudder deflection, but such a gyro CAN be used to maintain a constant bank angle or pitch attitude and it is in these two axes where ā€œheadingā€ hold gyros are being increasingly used in fixed wing models.

So then, a standard single axis, single channel rate gyro can be used on rudder and /or noswheel steering and if necessary the control out put from one channel can be modified (in direction , throw and center) by the use of a Match box type unit to fine tune both the rudder and n/s servos to achieve just the degree of control required. The gyro can be placed after the receiver and before the Matchbox thus acting as a damper on both channels or after the Matchbox to act as a damper on just one Matchbox output. Such gyros have a sensitivity or gain pot to allow the response of the gyro to be tailored to the aircraft requirement so that any yaw oscillation is opposed by instant correction generated by the gyro. Most of my jets, including the BVM F4 and Sabre, are so equipped and the use of a gyro has been particularly beneficial to my two BVM BobCats. This model uses the landing gear doors as airbrakes and the turbulent and uneven airflow around these flat plate, and very simple but effective, brakes causes some directional instability, oscillation, when the gear is down. By using a gyro on the rudder channel such instability is eliminated as the gyro gain channel is slaved, via a mixer, to the gear channel so that the gyro operates at high gain with the gear down, but at very low rate with the gear retracted. As the nosewheel steering is also controlled by the gyro take off and landing rolls are very straight with minimal control input as any heading deviation is instantly opposed by gyro output. I t should be noted that the yaw deviation is opposed by the rate gyro but it will NOT be returned to the original heading in this mode. This function has worked flawlessly in the Bobcat, the same model as reviewed in RCJI, for 6 years.

As the use of gyros for fixed wing aircraft began to take hold Futaba released a gyro specifically aimed for aileron use on these models and this unit incorporated a ā€œhold ā€œ facility and processed two channels on a single axis making it ideal for use on aircraft which utilize a servo on each aileron. Mark Savage was one of the early users of this gyro on his superb Vampire and has made this relatively small model rock solid in the air, no doubt aided by Markā€™s super smooth piloting ! The Futaba GY 351 processes two channels and can be used as a rate gyro or in the ā€œholdā€ mode. . The gyro has two servo reversing switches so that the gyro output can control servos in the correct sense. In addition the unit has two gain pots and these, respectively, adjust the gyro sensitivity, or gain, and the other adjusts the servo output allowing fine tuning of the gyro effect on the model. The gain of the gyro can be manually adjusted without receiver input (but then the gyro will work only as rate gyro, the ā€œbeginner modeā€) or a receiver channel can be connected via a fly lead and the effect of the gain by tx adjustment will vary dependant on the initial manual setting of the gain pot. Setting the remote gain switch or knob to neutral will reduce gyro effect to nil, whilst gain setting to one side will increase gain in ā€œrateā€ to maximum whilst rotation to the other side will engage the gyro to ā€hold ā€œ mode with increasing sensitivity. Whilst in ā€œhold ā€œ mode any stick deviation from neutral will switch off the ā€œholdā€ allowing normal control but as soon as the stick is released the gyro will hold the bank angle at the value present when the stick was released to neutral. Clearly, any trim input whilst in ā€œholdā€ mode will be seen as a control input so any trimming should be performed whilst in ā€œrateā€ mode and the neutral seen by the gyro when ā€holdā€ is selected will become the new neutral setting. The 351 has a tiny, but bright, LED which is off when in manual mode or gyro gain is zero, steady red when in ā€œholdā€ mode and flashes twice when it senses a stick deviation from stored neutral when in ā€˜hold ā€˜ mode. Futaba refers to their ā€œholdā€ mode as AVCS, angular velocity control system. Sadly the Futaba 351 gyro is no longer in production but is still available from some model shops. Increase in gyro use led to the incorporation of a gyro function in the superb Weatronic Dual Receiver and the latest Weatronic DRs the 12-26, incorporate a dual axis gyro system although both gyros work only in the rate mode.

The latest development in dual channel single axis gyros is the Fuzzy Airplane gyro from the German company ACT and one of these units was purchased at the recent Jet Power Show. This gyro contains the latest , state of the art, silicon ring sensor manufactured in Japan to a British design by SSS as mentioned earlier. The SSS sensor, highly protected by patents, uses an inductive effect vibrator and the manufacturers claim classĀ¬- leading resistance to shock, vibration and temperature. This is the unit used by Tommy Gleissner in his Jet World Masters winning Hawk and can be used in bothā€ rateā€ and ā€œholdā€ modes.

The ACT system is a two part unit comprising the electronic controller and the external gyro unit which is the SSS CRS03 angular rate sensor The unit processes two channels in one axis and each channel has its own reversing switch to enable servo output in the correct sense. There are two other dip switches, one to select ā€œnormalā€ or ā€œrateā€ mode, (only) or, in the opposite direction, it selects ā€œheadingā€ which functions at one side of the remote gain control travel whilst at the other side of the gain channel travel the gyro functions in ā€œnormalā€ or rate mode. A fourth switch allows the unit to ā€œlearnā€ the maximum servo travel it is allowed to command to avoid physical control system restrictions. In addition there are two pots one of which controls stickā€ fade outā€ (the deflection from stick neutral at which the gyro has no effect.) and the other controls gain in manual mode (ie without receiver input) or dynamic gain when the unit has a receiver gain input. Only by flight testing can this latter setting be made and the optimum gain is when the gain is set as high as possible without the servos ā€œhuntingā€ or ā€œwagging .

The tiny LED on the main case indicates the active mode with one flash indicating manual gain, two flashes the normal mode and the three flash sequence indicates the unit is operating in ā€œheadingā€ or ā€œholdā€ modeā€ .

So, the ā€œholdā€ mode can be used on ailerons to hold a constant bank angle, including wings level, (but it is NOT a wing leveler unless ā€œwings levelā€ was the starting point) , and that is the main application but care is needed when using a gyro for this function as there are hazards. Clearly, if the gyro is set in the incorrect sense the model WILL be uncontrollable and WILL crash. It should also be remembered that there is no speed input so even as the stall is approached the unit will still try and maintain bank angle by use of ailerons and at the stall that COULD lead to a spin so the use of ā€œholdā€ mode at low speed s should be used with caution.
The Futaba gyro was fitted on my BobCat on ailerons in the simple rate mode. Gain on both gyro sensitivity and control out put was set at 70 % of maximum. On the first flight the model was notably more solid in roll . However the ailerons were seen to be hunting, with quite large amplitude, low frequency oscillations. After landing the model the gain was reduced by about 20%and again the model was absolutely solid with no sign of hunting. As well as being much smoother it was very noticeable that when releasing any aileron input, the model stopped rolling very cleanly and with a positive ā€œlock inā€. Aileron exponential need slight adjustment to restore the same feel as when flying without the gyro but such adjustments were quite small.

As well as a controller on the roll axis there is no reason why a gyro should not be used as a pitch damper to smooth out pitch variations, or to hold pitch attitude. . However, it should be used with great caution in the ā€œholdā€ mode on this axis as the gyro will try and hold the attitude of the model such that it may rapidly lose speed and even if the model is stalled it will still make elevator inputs to try and hold the attitude at which the model was when the last stick input was made. Futaba cautions against the use of this mode during take off and landing and similar cautions were issued by Boeing in the use of an autopilot mode known as CWS (control wheel steering) which used the autopilot to hold a fixed pitch and/or roll attitude much the same as the ā€œholdā€ function on model gyros. .

A few other cautions when using gyros. It must be absolutely certain that the gyro outputs to the control surfaces OPPOSE the motion of the aircraft and an independent check to confirm gyro action is highly advisable. Several models have already been lost because of incorrect control outputs and a models with wrongly set gyros ARE uncontrollable even by the most skilled pilot.

When mounting the gyro it is essential that they are mounted in a secure but not rigid mounting. If the sensor unit were to come loose it will continue to work and may sense a totally different axis to that intended with the result that the model may become uncontrollable.

There is no doubt that gyros, correctly set, up can enormously improve flying performance and is the damping effect is particularly effective in gusty, turbulent conditions (when gyro gain increase usually has a very beneficial effect) and make even an average pilot look super smooth . You may care to give gyros a try, after flying with them Iā€™m hooked !

* Coriolis effect. In a rotating system, every point rotates with the same rotational velocity. As one approaches the axis of rotation of the system, the rotational velocity remains the same but the speed relative to the axis of rotation decreases. Thus to travel in a straight line lateral speed must be either increased or decreased and this change of speed is an acceleration (plus or minus) and the Coriolis force is the mass times acceleration of the object whose longitude is to be maintained.



References.

Silcon Sensing Systems: www.siliconsensing.com
Action Control Team (ACT) : www.acteurope.de
JR: www.jrradios.com
Futaba: www.futaba.com