HK401B gyro help

[themagicnumber]

I've just handed down my brushless car to my seven year old son, to help him get to grips with laying down power I put the gyro in the car but it acts like it has a mind of it's own and I'm finding it hard to set it up correctly.

I have it at the front of the car with what I assume to be the front of the unit facing forward and the top facing up it has a delay (I have that on 100) and a limit (I have that around 50%) it has DS (which is off) and DR (which is on normal).

I don't have any instructions as this was given to me in with a load of heli stuff and have no clue how to get this to be helpful rather than a hindrance...any help appreciated.

[Nitroholic]

Seen a few attempts at sticking a heli gyro in and expecting it to help the steering, keeping things straight and true. Doesn't work like that though. Took the pro's a while to get a working system.

[Tamiyacowboy]

OK its a copy version of a futaba 401 gyro one of the top cheapys around. 

 

you have two pots ( small dail adjusters ) on the gyro. 

one is for gain, the other for servo throw. 

 

install the gyro so its sticker sits up and the little arrow points to the front of the car. 

place the gyro mid center chassis and use good vibration foam ( you must isolate the gyro as its very sensetive) 

 

now plug gyro in and power up your handset, all trims center, power up the car and leave it alone.

DO NOT WIGGLE IT etc etc leave it alone while the gyro initalizes.

 

PICK UP CAR and turn it left and right , you should see the front wheels moving, infact the should be counter steering the skid your making gyro see. 

 

 

in real life the action is weird your not used to it and it seems all wrong. 

with the gyro turned off the car will spin out when you hammer the throttle on dirt, you will auto adjust steering to catch that kicker rear.

the gyro when turned on is told straight is good, anything else is bad and the gyro must override and counter that turn. so when you beef the throttle the steering stays straight

no wiggle or tail kicker it just nails down straight like an arrow. 

 

gyro, it plugs into the rx, then into a servo ( on a helicopter it would be the servo to control the tail rotors angle of attack stopping the heli spinning on the spot )

on your car the gyro sends a signal to the servo ONLY when it sees a rotation around its center ( its why most gryos are mounted mid chassis or nearly mid center a helcopter just behind the rotor head).

 

 

Throw this is how far the servo travels, if its set incorrect the servo will only move so much so stick it to 25% , you want all the throw for steering.

gain is how sensative the gyro responds to movement around its center , you adjust this higher for more straight line adjustment, or less so its not so strong.

the tail kicks but not right out the gyro comes into effect just before helping straighten out but not overly so.

 

 

Adding a gyro to a car is a differnet kettle of fish, vibration is 100% more than a heli , the gyro will feel every small kick of the rear every tweek knock click etc etc.

so that gain is very friendly and needs lots of fine adjustment to get it bang on.

 

CABLES : 

 

 

you have two leads one lead has a socket plug where your steering servo will fit in.

the second lead is two plug

 single yellow wire plug needs to be pluged into a THIRD CHANEL ( ie a dial if possible) this single lead is a signal lead and allows gain change via handset ( you must have it plugged in)

the second plug is just a standard power feed. so plug this into the BATTERY marked pin slot on the rx .

 

 

so your layout should be this 

 

channel three on rx (aka aux channel ) needs to have the single signal wire pluged into the signal pin for the spare channel needed.

the gryos servo socket lead is pluged direct into your steering servo

the black and red plug lead is placed into the pos and neg power pins on the rx .

 

thats how the drifters are fitting out the hk401b and running a third channel to control gyro gain

Edited March 2, 2015 by Tamiyacowboy

[themagicnumber]

Thanks for that reply TC. That's almost exactly how I set it up but when I gave it a quick test it just kinda steered whenever/wherever it wanted to..like it had a mind of it's own I'll have another look at it this weekend and take it out for a more thorough testing.

 

Thanks again.

[Tamiyacowboy]

Thanks for that reply TC. That's almost exactly how I set it up but when I gave it a quick test it just kinda steered whenever/wherever it wanted to..like it had a mind of it's own I'll have another look at it this weekend and take it out for a more thorough testing.

 

Thanks again.

 

 

yep it should do that. 

 

see whats happening is its so sensative untill its gained out it sees a slight movement a tiny knock and it triggers the system in. in a heli its called tail wagging where the gyro is to fair gained in

and is running a max 100% , toning gain down has the effect of making the gyro less sensetive to those movements it sees. and thats why you think its wrong

its just the gyro being to clever for its needed use and with some little tweeking it can be toned down

 

with the third channel running ( we use a dial so we can move from zero to ten (0% - 100% ) then we start to dial it either up or down.

in a heli this action is called headhold. the helicopters nose always points forwards , and its why it seems very weird to you.

 

to a heli pilot he will understand this feeling and be acustomed to the system doing its own thing leaving him to just add in a little left or right turn when he wants.

with a car your always tweeking the steering, making very minor adjustments  and this means YOU over ride the gyro. 

 

and as a little extra gift, here is the HK401B gyro instruction manual link 

 

http://atorie-m-m.main.jp/HK401B_manual.pdf

Edited March 2, 2015 by Tamiyacowboy

[Nitroholic]

Of course....tweak it too far...and it won;t work either. The car will have lost the tail before the gyro starts to compensate.

[NuttyProfessor]

I use a Futaba G190 micro gyro in my Vaterra V100, set to around 55-60%, perfect powerslides but once you press on, front wheels over compensate and wobble like hell, only need about 30% to be honest for normal bashing unless your boy loves powerslides

[themagicnumber]

 

 

 

with the third channel running ( we use a dial so we can move from zero to ten (0% - 100% ) then we start to dial it either up or down.

in a heli this action is called headhold. the helicopters nose always points forwards , and its why it seems very weird to you.

 

 

Thanks for another well written post and thanks for the PDF. I think I may have an idea as to why it's being crazy..you say to use a dial for the third channel?..I have a simple push on/off switch for the 3rd channel on the Tx (FS-GT2B) No way to adjust it as far as I can tell.

 

EDIT: I was just having a fiddle on the bench (can't take it out as I have no rear tyres for now) and I noticed that with it set up correctly (following your posts) it works fine..as soon as I hit that 3rd chan button on the Tx the gyro loses it's mind and goes back to being an entity to itself. So..if it works with the button off I'll leave it like that. I think maybe I had left the 3rd chan switch on the first time I tried to set it up without realising and that's what gave me the quirky results.

 

Edited March 4, 2015 by themagicnumber

[Tamiyacowboy]

 

 

 

yes usually we have the third channel, but you have to remember this unit is normally used with an aircraft handset so has like 8 or even more channels.

on a aircraft handset we get two way toggles - three way toggles - and dials ( pots ) we tend to hook the gyros signal lead for the adjuster channel into one of these channels on the handset that is a dial. 

 

on a rc land handset the third switch is a on-off, in signal terms thats zero percent or one hundred percent. where the air handset can go from zero percent all the way to 100 percent in 1 percent steps.

its adjustable in its range unlike an on-off switch. and thats why your seeing this unusual action , the switch is giving a full on or full off. full gain would mean the craft is very tail hoppy ie the steering would be very sensative and just be wild. 

 

as long as the gyro moves the front wheels when the truck slides out / rotates on its center around the gyro all is good, no need to mess with the gain switch for now.

but having more control over it is going to be better in the long run, you may find it needs adjusting when powering up on dirt .

 

now the cars gonna drive funny its going to drift, the gyro is a headlock gyro. and when fitted into a drift car should do and work like this 

 

Edited March 4, 2015 by Tamiyacowboy

[NuttyProfessor]

Mine is like that but at 35-40mph, just makes it more enjoyable to drive with a big power plant.

Can you not adjust the EPA on the 3rd channel to say 50% or less via a menu?

Edited March 4, 2015 by NuttyProfessor

[Tamiyacowboy]

Mine is like that but at 35-40mph, just makes it more enjoyable to drive with a big power plant.

Can you not adjust the EPA on the 3rd channel to say 50% or less via a menu?

 

it wont work . 

 

the works like this, 

 

my helicopter without a gyro i have to constantly add left and or right rudder if i did not the whole craft would spin round in circles. 

like a car doing doughnuts. 

now if we add a gyro into the servo line on the rudder, it senses this rotation and move the rudder to compensate. but it does this very very fast

millions of times a second..

 

now when a heli takes off sometimes you see its tail kinda wagging like a dog left to right, this is the gyro over conpensating. or under compensating.

so what we do is adjust this gain while we are in flight , when gain is in the sweet spot the helis tail sits dead still and the nose front. no flicking tail to left and right.

thats why we must have this very fine control on the gain.

 

gyros can be fun in a car, but drifting and off road racing most people frown upon the idea. it should be the drivers skill, not electronics.

but they can be installed and used if you make certain adjustments , if your on the gas and that rear steps out your either running to hard on the throttle for the grip there

or you overcooked the speed. a gyro can only do so much it trys to keep the truck in a straight line and this can sometimes be a bad thing.

you forget its wired in, hard corner to dift out of danger, hammer throttle and gyro say ohhhh yeah straight ahead ....... thud.

 

you may also need to reverse the gyro to get it to countersteer out of a slide, its all a playing game to see what works best. find the COG of car

front to back - left to right, now place that gyro bang in that spot  ( in a heli we mount the gyro right behind the rotor head roughly where the cog is 

doing this in your car gives you the best outcome from the gyro.

Edited March 4, 2015 by Tamiyacowboy

[NuttyProfessor]

Mine don't do that, whatever way I aim it, it goes. I let other people drive it and they always comment how balanced it is and how fast it can hold itself in a powerslide. Luckily my Vaterra V100 is a very balanced chassis.

[themagicnumber]

Thanks TC for taking the time to bother fully explaining this stuff Appreciated.