"Understanding Hiller Decay and other Skookum cyclic gains" soko & pg #30 johnahamelv

[fusionsx00]

Well not to boast or anything, but i am advancing


And im pushing the limits of my helis and electronics. Ive done my homework on setups troubleshooting, tweaking, eliminating interactions in flight.

Now im just working on my flying skills, and really dont want to tweak anything unless it affects my flights. I do my preflight checks, a little r&r every # of flights and just fly.

[soko]

Half of the fun for me is building/changing/tweaking the heli. The other half is flying

bdw: what's r&r?

[Luvmyhelis]

Originally Posted by soko

bdw: what's r&r?

[ Home > Spirits > Canadian Whiskey > Rich & Rare Canadian Whiskey ]










100% SL absolutely required!

[soko]

do fill your nitro heli with it or your own build in engine

[npomeroy]

I'm with Soko on trying understand these things. I think a confusing aspect is the way the numbers go: My understanding is they refer to Hiller decay RATE, i.e. a bigger number means the Hiller (stabilising) effect goes away more quickly.

Not wanting to divert the thread, but I generally fly with SL on, and am getting flying experience waiting to install a scale body on my Atom 500. I'm quite happy with big-air figure 8's, and have started practicing precision flying around cones spaced a few metres apart. I'm not very good at it, and wonder if with the SL on the heli is not responsive enough. I also wondered about the Hiller decay, but with SL on does the HD mean much anyway?

Hope you also enjoyed a sunny Christmas Soko.

Nelson NZ

[Scallybert]

Originally Posted by npomeroy

I'm with Soko on trying understand these things. I think a confusing aspect is the way the numbers go: My understanding is they refer to Hiller decay RATE, i.e. a bigger number means the Hiller (stabilising) effect goes away more quickly.

On a ‘real’ flybar, the cyclic pitch between the paddle and the flybar disc is what makes the flybar disc precess. This is the sum of what is set by the swash and the angle between the flybar disc and the mainshaft.

The latter part is (AIUI) the Hiller Decay part. If the swash is level, it makes the flybar disc return to level. If the heli leads the flybar, it speeds up the flybar disk precession.

My take is that on an SK-720, 100% HD is like a real flybar. 0% is no HD. 200% is ~doubling the HD effect you’d see on a real flybar.

I reckon I’m doing a similar kind of flying to you, and my HD is set around 35%.

[fusionsx00]

Originally Posted by Luvmyhelis

[ Home > Spirits > Canadian Whiskey > Rich & Rare Canadian Whiskey ]










100% SL absolutely required!

exactly what i need and do drink after i get done working on my helis.

im not a big drinker, but sometimes these things get frustrating, and i really dont like working on them, i listen to music, get focused on the heli and push myself to do it.

i guess toward the begining of me flying helis i did like messing with stuff that was perfect , now if its not broken, i leave it. too many times i have had bad luck, i mess with something that was fine, and i end up crashing, or breaking something.
maybee its all the crap i went thru trying to get this to work on my x5?

when im out flying, its nice and peaceful. i get home relaxed and dont even think about drinking.

[Luvmyhelis]

Originally Posted by fusionsx00

exactly what i need and do drink after i get done working on my helis.

im not a big drinker, but sometimes these things get frustrating, and i really dont like working on them, i listen to music, get focused on the heli and push myself to do it.

i guess toward the begining of me flying helis i did like messing with stuff that was perfect , now if its not broken, i leave it. too many times i have had bad luck, i mess with something that was fine, and i end up crashing, or breaking something.
maybee its all the crap i went thru trying to get this to work on my x5?

when im out flying, its nice and peaceful. i get home relaxed and dont even think about drinking.

I understand, I meant this as an offbeat joke. It actually took forever just to find a pic of the stuff. I haven't been able to even drink a beer much less anything decent in over 2 years, the meds I am on make me violently ill with any kind of alcohol.

Honestly I just want to see you up and flying in that perfect place of heli nirvana that you just so aptly described. I think everybody here feels and understands your frustration.

Personally all my helis are down right now with serious issues and have been torn down into shells. I am once again faced with the prospect of throwing more uber expensive parts on them due to design flaws in the already expensive parts I was using. Oddly as I just wrote that last sentence an epiphany hit me and it resolved my fbl head issue. Wow, thanks fusions! Had I not been in this exact spot doing this exact thing the solution would have never presented itself. An easy redesign of how my swash lock arms fit on the head. One problem down (maybe) several more to go!

[fusionsx00]

my x5 is up and running , not with skookum, but none the less it is.

its my daily flyer, and i ussually do 12 packs when all is running good.

i guess one good thing that came of this is my abilty to see a problem before it

causes a crash. its almost a gut feeling, but there has been a few times i spool up

and something feels off, i shut down drive all the way back home(3min) and start

checking stuff that wasnt in my preflight checks. and the very first thing i check is

whats wrong.

im looking forward to getting my 700 size, but not learning the quirks of it, all helis

have them.

[jhamel]

The SK-720 has lots of gains and adjustment possibilities to fit various flying styles. However, there is not sufficient information to intelligently go about making these adjustments for the individual machines and flying styles.

I would like to concentrate on Hiller Decay. According to the 3.00 revision of the manual:

Causes accumulated Hiller response to decay back to neutral, to make the gyro more forgiving of perturbations. If you watch a helicopter with a flybar in hover, you’ll see the flybar’s disk offset for a moment then drift back to level after a sharp control input. This option provides the same effect digitally.
A value of 100% here can help smooth out rapid tic-tocks, piros or other 3D maneuvers, especially repeated ones. However, high values for Hiller Decay will also limit the gyro’s ability to hold steady in gusty wind or trim the helicopter precisely in hover.

Unfortunately, that blurb discusses a flybar. Although I have used flybar helicopters in the past, I never really understood how it worked (increasing or decreasing the size and/or weight of paddles), so that explanation makes it difficult for me to understand Hiller Decay in terms of a flybar.

Interestingly, the Trouble Shooting Guide of the manual does not discuss the Hiller Decay at all. What happens when it is too high or too low.

I understand that you want to trim the helicopter on a windless day at 200% Hiller Decay. For 3D flying, it is recommended to keep the Hiller Decay between 100-150%. For scale flying, it is recommended to keep Hiller Decay at around 75%. So it seems that the lower the Hiller Decay, the more stable and less agile the helicopter will be.

I have read other threads here in HF discussing Hiller Decay. The threads discuss how the Hiller Decay gives you the flybar feel, which again I do not understand what a flybar is suppose to feel like. However, the threads do not say which value (200% or 75%) gives the flybar feel.

Maybe, Hiller Decay has to do with how "locked in" attitude-wise the helicopter feels after centering the cyclic stick? Higher values (200%) completely loose, and lower values (50%) really "locked in"? Will the helicopter make a robotic stop attitude-wise when I center the cyclic stick with a Hiller Decay set to 50%? Will the helicopter make a smoother and softer stop attitude-wise when the Hiller Decay is set to 150%?

Also, if lower Hiller Decay values makes the helicopter more stable, should I set the SL bailout bank with a lower Hiller Decay (50-75%), even though the other bank used for flying has a Hiller Decay set to 125%?

I would like to read other pilots views and understanding of this mysterious Hiller Decay.

[dpelletier]

These are really good questions... I'm sure Georgi will chime in to illuminate us

[georgi UK]

=] John, your thread is now merged with soko's, to keep valuable material under one roof,

for some reason? >ME< yours was added to the bottom, sorry! but anyway it's in chronicle order.

i think soko's thread covers it, but take it from here, as I am sure you will!

[jhamel]

Originally Posted by gmcallister

=] Hiller Decay belongs to the gyro side of things...

As opposed to belonging to what? The transmitter? The environmental/wind conditions?

[jhamel]

Originally Posted by martin_

Other than different flyght caracteristic with different hiller decay value, the decay is how fast the swashplate return to level after the cyclic command is released, the faster it level, the faster you see if your heli is well trimmed for hand free hover, if its too slow, it can mask the drift.

Which way is consider fast return, 200% Hiller Decay or 50% Hiller Decay?

[jhamel]

Originally Posted by gmcallister

=] for some clarity here, Hiller Decay is a stability component of the gyro, the lower the % the more stable the heli becomes.

for trimming purposes this is temporarily increased to its max 200% value where the heli becomes drift exposed (less stability) to assist this adjustment process.

HD is when you let go of the stick! ie how quickly it returns to level.

stick centered = Hiller Decay + low values = stability

According to the above statements, it seems that one would want a HD of 75% or lower for the SL bailout (panic button).

[jhamel]

Originally Posted by Scallybert

My take is that on an SK-720, 100% HD is like a real flybar. 0% is no HD. 200% is ~doubling the HD effect you’d see on a real flybar.

Is the above statement accurate? That would explain a lot if it is.

[georgi UK]

Originally Posted by johnahamelv

As opposed to belonging to what? The transmitter? The environmental/wind conditions?

=] John, here we go! some SK settings are for the gyro/heli, some are for the pilot/heli, hiller decay is for the gyro/heli, bell gain is for the pilot/heli.....

[Colonny5]

Clear as mud.

[dpelletier]

Originally Posted by Colonny5

Clear as mud.

+1

[georgi UK]

=] paused!