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Old Aug 02, 2011, 12:09 AM
Team Wack-a-Mole
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Yes, the Futaba 401 is the most vibe INSENSITIVE gyro I have ever used. I've thrown it on helis that shake like a rattlesnake and it held the tail. HK401 is piezo. Any piezo will be more vibe sensitive than a Futaba 401. The GA250 is better at vibe tolerance than the GY48v or HK401 but I would not say it's as good as a Futaba 401 in the reguard. The slower vibe of a four stroke though will make a gyro controlled servo vibrate as well under the gyro control. Moving the gyro further from the engine or putting it with Zeal tape helps. I had Zeal on my gyros on of my 1.20 YS powered Spitifre (RIP)
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Old Aug 02, 2011, 12:47 AM
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scott page's Avatar
United States, WA, Richland
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I'm pretty sure this is the first time "zeal" tape has been mentioned I. This thread. I'm pretty sure because I've read every word at least once.

Ok Melnic, how are your disciples suppose to learn when you hold out.

So ... For the gyro impaired, ¿que' zeal tape ?
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Old Aug 02, 2011, 08:08 AM
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Zeal tape is this kind of green squishy tape that comes in a 4x2 " sheet/ You cut it to fit what you want it for. it is the best at removing any vibration from something you need to isolate it from.
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Old Aug 02, 2011, 11:10 AM
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scott page's Avatar
United States, WA, Richland
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Quote:
Originally Posted by Spidious View Post
Zeal tape is this kind of green squishy tape that comes in a 4x2 " sheet/ You cut it to fit what you want it for. it is the best at removing any vibration from something you need to isolate it from.
Am I just not finding the right place to purchase, or is it really over $10 for a single piece???
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Old Aug 02, 2011, 11:37 AM
Team Wack-a-Mole
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Yup, not cheap.
That sheet will allow for a number of gyros.
I don't recall but it's about 5"x2"????

Zeal at Amain
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Old Aug 02, 2011, 04:37 PM
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Perhaps old age leads to impatience, but having not received my updated GA-250s from Meng yet I had a reckless moment and ordered another handful from HK with EMS.
I'm ready to wring them out! I torque rolled my escapade on take off yesterday and ended up snapping the fuse in half. It was second flight after being rebuild (nicely). First flight was on conservative 4 cell pack. This flight was on 5cell which gives it quite a bunch more punch. Was having an issue as tail lifted so I punched it to get airborne - .......

Gyros on board would have saved it - but I hadn't finished checking it out yet.

:-(

Nobody to blame but myself. I have rudder gyro in my shoestring - which is also a handful to take off with any sort of scale roll out without a gyro. It's got 6s on same motor as the Escapade. One caveat - my spotter is instructed to remind me to turn off the gyro after take off because WOT out of a split-s is amusing to everybody but me. I just wet myself when it does the salmon dance.
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Old Aug 02, 2011, 05:39 PM
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Quote:
Originally Posted by otrcman View Post
One of the things I wondered about was resistance to airframe vibration and overall stability. I have a Futaba 401 and a couple of HK 401b's. I think the Futaba is a MEMS and the HK is a piezo. Is that correct ?

The difference in operating behavior between the Futaba and the HK is night and day. The Futaba is a dream to use and once set up you never even know it's there unless you turn it off to see the difference in the airplane's behavior. On the plane with the HK's there was a lot of jitter and they seemed more vulnerable to limit cycle in the air. I finally removed the HK's because the improvement in flying quality was no more than a push relative to the added weight and bulk.

If I had another plane that really needed a rate gyro right now I'd go ahead and spend the money for another Futaba 401. I don't like spending money any more than the next guy, but from what I've seen so far, you get what you pay for.

Where would you put the GA-250 relative to the Futaba 401 and the HK 401b ?

Thanks again,

Dick
The special issue of FlyRC - Radio Control Jets has an article of a turbine F-16 that uses a Futaba 401 on the rudder. They included a picture of the control deck inside the fuse showing the gyro. (A Habu 32 is on the front cover of this issue)
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Old Aug 04, 2011, 09:47 PM
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Japan
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Just started setting my GY48s up. How sensitive are they to EMI etc., and can they be mounted on a wing tip?
The best spots are: about 5cm from teh motor; next to teh ESC; possibly under the 2.4 ghz VTX.
Alternativley, it woudl act well as a wing tip counterbalance for my VTX.
There are other mount options, but they are not as efficient.
Thanks

EDIT: I'm getting a bit confused watching the video. I have an FF8 radio and am not sure which channels to put the gyros on and how to program the radio for gain, etc. This was a heli radio, so there are many switches, as well as 3 adjustment knobs on the face.
I tried the ailerons with the red plug on channel 8, this allowed me to turn the knob to switch between rate and HH and sensitivity of both. However, it seemed really gittery, and was murmering even at "0" on the dial, which is the equivalent of OFF. Adjusting teh gyros delay and limit screws didn't seem to make that big a difference.
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Old Aug 04, 2011, 11:06 PM
Team Wack-a-Mole
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I never put one that close to an ESC or motor. More the current, the further I like to keep them from each other.
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Old Aug 04, 2011, 11:10 PM
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These are pulling about 25A. The VTX is 500mw.
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Old Aug 05, 2011, 08:56 AM
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Here is someone who got an SK-720 flybarless heli unit to work on an airplane:

Erstflug Parkzone Extra300 mit Skookum SK720 am 2.8.2011 (5 min 49 sec)


If the option to turn off piro compensation and tail compensation are in Align's 3g software, then it might be possible to use it for airplanes also. I was opposed to this in the beginning do to the mixing flybarless units use for heli's.

Will have to keep an eye out for a 3g unit (sells for around $70 used these days). The SK-720 has self-leveling by the way, and I've been asking Skookum to develop firmware for airplanes (FPV/photography more likely, since it also has GPS capability) use. I have a feeling that they will eventually....
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Old Aug 05, 2011, 01:52 PM
Team Wack-a-Mole
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Keep pushing them. I do prefer the rate mode over Heading Hold. I think it feels more natural.
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Old Aug 05, 2011, 05:23 PM
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Nederland, ZH, Capelle aan den IJssel
Joined Feb 2011
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This is a verry interesting thread on "elevon/v-tail gyro mixing without a elevon/v-tail mixer".

It really looks to be unbelievable, but i tested it and it works for real..!!

http://www.rcpowers.com/forum/showth...von-mixer-unit

Eurofighter Typhoon Maiden. Elevon gyro mixing, 6mm depron tomhe plans. (3 min 21 sec)
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Old Aug 05, 2011, 09:28 PM
Team Wack-a-Mole
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Maryland
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remko, I did that back in June
In the case of the doghouse, it was not to deal so much with the wind but the bad tendancies of well, a flying doghouse. It was MUCH better with the gyros.
I also dissagree with his formula. I mounted mine angled at more of an angle since the pitch is less sensitive than roll
http://www.rcgroups.com/forums/showp...postcount=1107
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Old Aug 06, 2011, 12:13 AM
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GA-250 bench results

I spent all day with the GA-250's I just received directly from Assan. These have all of the updates on them. I'm not sure what they will look like label wise coming from HK -- yet. I have some ordered through that channel too so I can give them the same test as those directly from Assan. Those I received yesterday did not have a white or red label.

Fixed is the midrange jump to program mode. I could not get them to reboot or jump to program mode while in use one time.

Fixed is the random change to different servo types. I did toast three servos -- but all three were my fault.
I did the vast majority of my observations using cheapest analog servos for obvious reasons. I did some brief connections with digital, just for reference. I don't have surplus digital servos lying around so when I'm confident that I've checked out the analog thoroughly, I'll break out the digitals.

Problems I found:
1. They arrived in 1520us 333hz right out of the box. The Red label batch I purchased in May (or June?) were 960us 333hz right out of the box. Meng said the default was not 960/333 .. so I assumed they would be. They were not. (First servo smoked)

2. AVCS (HH) showed slow, but progressive drift over 30 minutes of sitting idle in one setup. This was not noted in the other setup. Temperature was stable. Tomorrow I'll check for drift with shifting temperature .

3. The manual really really needs to be rewritten. The instructions assume that you are setting this gyro up on a heli rudder. Hook up to ailerons or elevator of a plank and the commands you use when programming are different -- AND you should only program one gyro at a time and have the other disconnected -- or you might inadvertently change the servo type on the gyro you are not programming and are ignoring... (second and third servo smoked). For example.. if you're using the right stick (mode2) to program the elevator gyro and ignoring the aileron gyro.. ya. Stinky smoke in the wings. At first I thought the gyro reset itself --but I'm confident I did it when slopping around with the right stick trying to figure which elevator direction was analogous to rudder left.
-- Additionally the manual should have a big fracking warning on the top .. that reads "If you don't set up the servo type BEFORE hooking up the servo to the gyro you might make smoke".

Um.. that's it for problems I found. Really relatively minor depending on how that drift thing works out with further testing. I might have to write an English manual that addresses setting these up for winged aircraft.

Things I liked.

In Rate mode these are fast, solid, and very crisp. I mean, I had them on right next to me for an hour while I was soldering and never a peep. But when they detect motion, they move quickly and don't seem to bounce. Bouncing is hard to detect on the work bench. A 4 point roll will show bounce -- but I'm not ready to put them in a plane that will do a 4 point roll.

They are virtually immune to vibration. I hot glued one to a styrofoam motor pod on a Sky Surfer/Bixler and it was flawless with the motor at half throttle. I didn't go full throttle because it makes a mess of my shop area. I mounted one with velcro... no problems. Now -- I'm using smallish electrics with these right now. A nitro Heli has a totally different vibe -- but I don't have a nitro Heli. If they pan out they'll go in a 1.5 meter foam Yak next. Then.. my Shoestring if I'm feeling good about it. But, they were more vibration resistant, and moved the servo (even cheap cheap cheap analog) more crisply than any other <$50 gyro I've tested. By crisp, I mean at extreme travel, they quickly hit the spot and stop then hit the next spot and stop. If they were a person I'd say they are quick, precise, and confident.

Analogy attempt -- when you turn on an incandescent light bulb they seem to turn on immediately, when they flash on and off they seem to be immediately flashing on and off. Now do the same flashing with an LED and suddenly the incandescent bulb seems ramp up for full brightness, and fade slower -- because the LED flashes with a square wave response, and incandescent with a sine wave. Not sure if that works for anybody -- but all of the piezoelectric gyros I've used seem to react fast until being next to a GA-250. The GA-250 seems to respond with a square wave and piezo with sine wave response. I'm sure it's just the difference between the mems and piezo -- but mems for $10 and now they seem to be working as I'd like!!


I'm not recommending anybody use these, yet. However I'm willing to put them in the air, when they never made it off the bench the first go around. Tomorrow I'll test them on a pusher glider (Bixler/Sky Surfer) using aileron and elevator. I'm using a Turnigy 9x with stock firmware and I've got each gyro on a separate pot. My full time TX is Futaba 7C but I want two pots, and the 9x I've been fooling with meets that requirement. (I'm really impressed with the 9x... but like the Skysurfer/Bixler -- it needs a few mods. )


Ok -- GA-250 Day 1. Bench test .. gyros passed, are deemed safe and ready for flight testing. AVCS drift needs further investigation, and need to write a better manual.
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