landeck

My Feedback: (1)

[quote]ORIGINAL: eclipse3g

Beautiful Waco, Ken! May be your Waco’s power plant is balanced very well???

I will try to mount my GYA351 on the heavy duty 3M Velcro tape. I heard that is not so precise for gyro because this method allows gyro to move a bit from side to side. But, I think it’s not so crucial for an aircraft rudder gyro. I use Velcro tape to mount all my receivers on electric as well as glow planes and have never had any failure (detachments, crystal and filters problem, cable disconnections and so on). However, I can post my test fly results only after winter time. I do not fly in winter.

>>>>> One thing you might check is to see if you have the gain set too high

otrcman

If I understand correctly, your rudder oscillates even on the ground when the engine is at full throttle ?

If so, then it's structural feedback rather than aerodynamic and can be treated differently. With structural feedback, the engine vibration is shaking the airframe and the gyro is feeling the shake and interpreting it as airplane motion. The gyro moves the rudder to compensate for the airplane motion that it thinks is going on. So we need more isolation between the gyro and the airframe. That's what the servo mounting tape is for, but sometimes it isn't enough. The problem is that the gyro is so light that there is too little flex going on in the mounting tape.

As an experiment, you can try adding weight to the gyro. Wrap some solder around the gyro (an ounce or so) temporarily and run the engine again. If that does the trick, then you can do it more permanently by sticking a layer of tape to the airframe, then a small square of metal (aluminum, steel, lead, etc), then mount the gyro to the metal using another piece of tape. The metal square needs to weigh an ounce or so to be effective.

The GY401 has a "delay" adjustment, which I don't really understand. Perhaps one of the more experiences folks can chime in here. Is the delay simply cutting off the high frequency inputs ? If so, then you might be able to cure the vibration problem by adjusting the delay. The frequency of the vibration is far higher than the frequency of the airplane body motions, so by cutting off the response to higher frequencies you may be able to cure the shakes without affecting the flight performance.

Dick

summerwind

check out the price on the Futaba GY401 at this place,

http://www.sdshobby.net/futaba-gy401...pjccrpejmd0tr3

there seem to be some good reviews

but as with any knockoff, you get what you pay for including possibly a big rusty nut

eclipse3g

My Feedback: (5)

Thx Dick!

I think you right. I will put a metal square between standard Futaba mounting pads. Now I also understand, why we have another adjustment trimmer on the gyro. On GYA350-352 it named "control trimmer". For me that name has no meaning at all. During a gyro test (the engine was off) I tried to turned it from 0 to 100% and had no effect. Eventually I left it in 100% position. I will try to play with that trimmer (we can call it a delay trimmer for simplicity) later when the engine runs.

>>>> check out the price on the Futaba GY401 at this place

rcmiket

What gain are you all running on the 401. On a heli we use the gear channel travel adjust to control the gain over 50% is HH under 50% is rate. On most of my 500 and 600 size heli's I'm running right around 63%. How we determine that is we fly the heli and lower the gain till the tail won't hold. On a aircraft I'm guessing it would be a different set up.
Mike

BEAR-AvHistory

Right now on the HK401b I use +-80 for HH & Rate. Thing is I use the flap channel (3 posistion switch) so I can also use 0 to cut the gyro out of the loop.

rcmiket

Interesting thanks. That's high compared to a heli.
Mike

summerwind

[quote]ORIGINAL: eclipse3g

Thx Dick!



>>>> check out the price on the Futaba GY401 at this place

otrcman

deleted post

otrcman

[quote]ORIGINAL: summerwind


[quote]ORIGINAL: eclipse3g

Thx Dick!



>>>> check out the price on the Futaba GY401 at this place

summerwind

Dick,
i'm betting that it is as well.
for 20 bucks though i figured what the heck.
i have also bought one (if it ever gets here) of the HK401's from HobbyKing for 13 bucks (can you say cheep).

the GY401 i ordered from Tower is suppose to be here on Monday.
will be neat to compare them.

the close up shots look like a gold plated connector for the one that is a fake, and it has a green wire instead of white which is a dead giveaway.
what i really want to do is compare the counterfiet to the HK401.

summerwind

Dick,
just realized where you are.
we have a shop in arroyo.........i go there quite often.
is it raining?

otrcman

Not raining right this minute, but it's been coming and going all day. And the weatherman promises more tomorrow, along with wind. I didn't even bother to charge up for tomorrow.

What shop do you have ? Love to have you visit when you're in town. We seem to have common interests.

The difference between the "real" Futabe GY401 and the clones may be not only construction quality but also the type of sensor used. I'm completely out of my depth here, but it looks like the Futaba uses an SMM sensor and the clones use a piezo type. From what I've read, the SMM type is more expensive, but is less prone to temperature drift. Here is a quote from another thread regarding the differences between the two types of sensors:

"The Tokin and Murata sensors work well,..they are piezo sensors, I used them in various gyros for several years,..but they are very temperature dependant and therefore tend to "drift" on centering during a flight. The SMM sensors in all the new futaba gyros are far superior. I'm gonna have to look at that web site to see just how they work, but I've been so impressed with the GY401/502/601 that all my machines have been switched over to these in the last month. Now I've got a drawer full of "obsolete" Piezo gyros that will probably never be used again. The SMM gyros are _that_ good. Definately an order of magnitude leap in performance."


Dick

rcmiket

It's a knockoff. Read both good and bad reports on the heli forums.
Mike

summerwind

Dick, thanks for posting that.
being a bit (ok a lot) anal i disect every aspect of a gadget til i fully understand it.
the price of the clone is self explanatory. for what the Futaba GY401 does i even think it's price tag is well within reason although others find it to be expensive.
the clone and the HK401 have some good reviews, but for me neither will ever see service in any of my planes. what i want to do with them however is experimentation and learning.
i'd much rather screw up a cheapie to learn how to set and adjust than to goof up the Futaba unit.
both clones are so cheap, it'll be fun for me just to see what they can do in a mock up, and i'd like to see how the components compare.
i have buddies who are now installing cheapie Gyros and have some issues in the air..............they's never spend more than like 60 bucks on a gadget. like anything else, you get what you pay for.

not sure when the next time i'll be in AG, but i would like to meet you too. i use to be the only one working over in the area, but now i just come over when the current tech is over his head, or he has an issue he can't solve.

summerwind

seems a lot of guys were taken already by fakes from barfbay.
a lot have reported that thes fakes do work for typical uneventful flying.
the ones that are mad are the guys that paid 70 bucks and more and got a GY401 with a rusty nut inside used as a spacer.

anyone who is reading this, i have posted a link to a 20dollar GY401. i have assumed anyone would know that it is not the real thing. do not buy it unless you are simply having no problem burning a 20 dollar bill for nothing more than curiosity.
i'm interested in the knockoff to see how it compares to another even cheaper gyro.
i have also edited the original post where i linked to the knockoff so that you know it is a fake.

Big_Bird

My Feedback: (1)

I finally received the HK401B yesterday. I haven't had a chance to see how it operates but may find some time today. I'm still amazed that a company can ship anything like this half way around the world for $15.78 including shipping.

I understand that temperature drift in the sensor element could be a problem in a helicopter because of the length of time that it is used during a flight. However, from AVCS initialization on the runway in the Bucker Jungmeister to liftoff may not be over 10 to 15 seconds. The gyro is then put into the rate mode. I can't believe that temperature change in that time period could cause a problem.

I have an old Rookie test bed airplane that I will use to try out the HK401B before I put it into something better. Since I mostly fly scale airplanes and giant scale at that, the cost of the highly reliable GY401 is pretty insignificant.

opwan

My Feedback: (2)

Get a heli gyro with HH from E-flite, they work just fine, put it on a switchable channel and turn it off at liftoff. Simple

otrcman

I'd really like to try using gyros in all three axes at the same time. Rate only, of course. I have tried each axis individually and can see some improvements in each one. Yaw is the most dramatic improvement for takeoff and landing naturally. But in flight I really liked what the gyro does to the roll axis. The airplane becomes very "steady" feeling, much like a bigger plane. Pitch seems to be the least noticeable, although there is still some benefit. In the landing flare it seems to be easier to get a smooth touchdown without ballooning.

Most of my experimentation has been with expendable ARF's a GWS Tiger Moth 400 and an Electrifly PT-19. On those I wouldn't mind using the cheap gyros. As a matter of fact, I flew the PT-19 with an old Futaba mechanical gyro just to see how well it worked. Using three good gyros in an ARF, it will be easy to have more $ tied up in the gyros than in the whole rest of the plane.

Has anyone actually heard of a gyro failure incident and what the results were ? I can visualize a hard-over servo, which would almost certainly be curtains for the plane. With all the heli flying using gyros, surely someone has had a failure.

Dick

Big_Bird

My Feedback: (1)

Dick, not a problem with a modern gyro but once I nearly lost my Ziroli B-25J with an Airtronics spinning gyro on the rudder. It started generating a lot of electrical noise. I did get it down safely and took it out. Never replaced it.

Gremlin Castle

My Feedback: (14)

Like Big Bird I have not seen or heard of a total failure in a modern solid state gyro. Most problems are operational and programming mistakes that the operator does not want to admit to.

The chances of an airplane going hard over into the ground are much more likely to be pilot induced rather than gyro/servo related.

Again like Big Bird I only use rudder gyro on a few planes that can be problematic under certain runway and wind conditions.
We both fly Futaba equipment and fly most of the same fly ins so I guess we share similar positive results in using gyros on the rudders of select squirrley aircraft.
Here is one of mine that is much more assured of a straight line take off with no drama.

landeck

My Feedback: (1)

My HK401B gyros arrived today. All you get is the gyro in an unlabled plastic bag, no instructions or anything else. An initial examination turned up that the cut outs for the switches and pots are covered with clear plastic of the label. A model knife will be needed to cut out the openings. Also there is no heat shrink tubing on the split pig tail. Later this afternoon I will make the internal modifications suggested in an earlier post to help prevent vibration damage. Following that I will give it a basic test to see how it works.

Big_Bird, I agree with you that temperature drift should not be a problem with this servo when used on an aircraft rudder for takeoff.

Bruce

Big_Bird

My Feedback: (1)

Before a GY401 was put in that Byron Wedell-Williams racer it was a real bear in a cross wind takeoff. Now with the gyro it is a real pleasure to takeoff under the same conditions. As a racer, it really lives up to its reputation of being fast.

Big_Bird

My Feedback: (1)

Bruce you are right about no instructions. I guess that the nice sheet of decals advertising the product was a good substitute for instructions.

landeck

My Feedback: (1)

Correction to my above statement. The label is cut out for the switches and pots. But there is a clear sheet covering attached to the switches inside the gyro. When you take it apart to do the modifications for preventing vibration damage, be sure to remove that clear covering so that you can get to the switches.

Bruce