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Old Apr 01, 2010, 01:45 PM
Which shall it be, Passworthy?
Near Dallas, TX
Joined Jun 2007
2,495 Posts
Question
Optima 6 shadowed?

I recently gave in to the urge to go 2.4GHz with my Eclipse 7 and bought a Hitec module here on the forums. Got an Optima 6 rx and installed it in a 32" ws profile foamy (replaced a Micro 05S; the Optima weighs 5 or 6 grams more, by the way, with full case, BODA antenna, and antenna mount).

I have the rx in a slot cut under the wing in the vertical fuse piece; the antenna points straight back, positioned just under the horizontal fuse piece.

Took the Xiphos (that's the plane's name) out to "maiden" the upgraded radio system. Started out fine, except that I had dialed in too much control throw. After a couple of minutes of flying, I had the plane coming toward me (almost directly) and it *seemed* I lost control for a couple of seconds. I kept pushing the aileron stick further and further to turn then suddenly it "caught" and the plane almost violently turned. Almost the same scenario happened on the 2nd flight. In both of these instances the plane was relatively close to me (no more than 20 yds?) and pretty much pointed at me.

In going over this in my mind it occurred to me that I may have broken a basic rule of 2.4GHz antenna placement. With the antenna located longitudinally near the centerline of the plane, was it "shadowed" by the motor?

For complete disclosure I will note that I have been flying Spektrum for some time, mostly with 6100 rx's, without issue of any kind.

I don't recall any repeats of this behavior on the 3rd flight (2nd battery), during which I flew predominantly further away and higher. Now, there was a little wind, and this plane has a lot of wing area and only weighs about 16 oz., so that could have contributed to my apparent momentary loss of control.

I think I'm going to change the orientation of the antenna, maybe poke a hole vertically through the horizontal fuse for the antenna. What do y'all think?

Dave

One more factor -- I was running the radio in scan mode.
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Old Apr 01, 2010, 04:12 PM
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Joined Aug 2002
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Quote:
Originally Posted by hancockdw View Post
I recently gave in to the urge to go 2.4GHz with my Eclipse 7 and bought a Hitec module here on the forums. Got an Optima 6 rx and installed it in a 32" ws profile foamy (replaced a Micro 05S; the Optima weighs 5 or 6 grams more, by the way, with full case, BODA antenna, and antenna mount). I have the rx in a slot cut under the wing in the vertical fuse piece; the antenna points straight back, positioned just under the horizontal fuse piece. Took the Xiphos (that's the plane's name) out to "maiden" the upgraded radio system. Started out fine, except that I had dialed in too much control throw. After a couple of minutes of flying, I had the plane coming toward me (almost directly) and it *seemed* I lost control for a couple of seconds. I kept pushing the aileron stick further and further to turn then suddenly it "caught" and the plane almost violently turned. Almost the same scenario happened on the 2nd flight. In both of these instances the plane was relatively close to me (no more than 20 yds?) and pretty much pointed at me. In going over this in my mind it occurred to me that I may have broken a basic rule of 2.4GHz antenna placement. With the antenna located longitudinally near the centerline of the plane, was it "shadowed" by the motor? For complete disclosure I will note that I have been flying Spektrum for some time, mostly with 6100 rx's, without issue of any kind. I don't recall any repeats of this behavior on the 3rd flight (2nd battery), during which I flew predominantly further away and higher. Now, there was a little wind, and this plane has a lot of wing area and only weighs about 16 oz., so that could have contributed to my apparent momentary loss of control. I think I'm going to change the orientation of the antenna, maybe poke a hole vertically through the horizontal fuse for the antenna. What do y'all think? Dave One more factor -- I was running the radio in scan mode.
Why use Scan mode, are you flying in a very dirty 2.4Ghz area? if the receiver loses power, indicated that no problem with 2nd battery, it will take longer to re-bind than when in Normal Mode.
AFHSS - Normal & Scan Modes Explained includes Redundant (Dual) Receivers.
Hitec Spectra 2.4 GHz and Optima RX Review of AFHSS in operation -Video #3.
AFHSS - How To Select Optimum Channels - For Your Field
suggest use of SPC port
Optima RX - SPC Cable for Optima RX & Use Of SPC - detailed.
and much more info
Aurora A9, Spectra Pro & Optima - FAQ & Undocumented Features - Mixes, Setups, Tips. {frequently updated}

Regards
Alan T.
Alan's Hobby, Model & RC FAQ Web Links
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Old Apr 01, 2010, 07:08 PM
Which shall it be, Passworthy?
Near Dallas, TX
Joined Jun 2007
2,495 Posts
Quote:
Originally Posted by A.T. View Post
Why use Scan mode, are you flying in a very dirty 2.4Ghz area? if the receiver loses power, indicated that no problem with 2nd battery, it will take longer to re-bind than when in Normal Mode.


Regards
Alan T.
Good question, Alan. I plan to attend a couple of fun fly days here in North Texas in the coming weeks, and this plane will come with me. So, I rebound the RX in scan mode. Yes, I know Mike said they flew at Joe Nall in normal mode. And I understand it will take longer to reconnect after LOS: that's one of the questions I have about my experience. I believe my loss of control, if that's actually what it was, lasted only for about 2 seconds each time. Is that consistent with Hitec's expectations of behavior? Or maybe I'm barking up the wrong tree?

Dave
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Old Apr 01, 2010, 11:17 PM
Hitec/Multiplex USA
MikeMayberry's Avatar
Poway, California, United States
Joined Sep 2000
4,200 Posts
The first thing I would do is rebind. You should not have any shadowing no matter what the antenna orientation. At least we've never seen an instance of it.

Yesterday Hitec team pilot Joe Manor accompanied by aviation icon/living legend Burt Rutan flew a full carbon wing with carbon/Kevlar fuse D80 http://www.manormodels.com/main.sc to speeds over 350 Mph with the single antenna Optima 7 mounted inside the fuse. He did mount it vertically though.

I'd also do some power down range checks if you think there is a problem.

Mike.
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Old Apr 01, 2010, 11:21 PM
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Quote:
Originally Posted by hancockdw View Post
Good question, Alan. I plan to attend a couple of fun fly days here in North Texas in the coming weeks, and this plane will come with me. So, I rebound the RX in scan mode. Yes, I know Mike said they flew at Joe Nall in normal mode. And I understand it will take longer to reconnect after LOS: that's one of the questions I have about my experience. I believe my loss of control, if that's actually what it was, lasted only for about 2 seconds each time. Is that consistent with Hitec's expectations of behavior? Or maybe I'm barking up the wrong tree?
Dave
Unable to give a definite reconnection time as so much depends upon battery condition, servo demand and other associated factors which depress voltage. e.g. holding aileron & elevator servos over during high load manouver and time to release either or both.
How good was your range test with motor running and working the servos before flying that day? Similar antenna placement (along roll access) through much larger block of metal (DLE-55 petrol engine): Range check 300ft through DEL engine & firewall
The following reports may assist.
A look at 2.4GHz radios with in built telemetry whilst you would be most unlikely to see the receiver's blue LED flashing whilst flying, you may be able to set up on bench applying light load to servos whilst operating system
One Very Close Call
Brown Out - RX Voltage Sag
AFHSS - ID-Setup A.K.A, binding or linking Spectra Pro Module <> Optima Receiver - in need.

Regards
Alan T.
Alan's Hobby, Model & RC FAQ Web Links
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Old Apr 02, 2010, 01:41 PM
Which shall it be, Passworthy?
Near Dallas, TX
Joined Jun 2007
2,495 Posts
Quote:
Originally Posted by MikeMayberry View Post
The first thing I would do is rebind. You should not have any shadowing no matter what the antenna orientation. At least we've never seen an instance of it.

Yesterday Hitec team pilot Joe Manor accompanied by aviation icon/living legend Burt Rutan flew a full carbon wing with carbon/Kevlar fuse D80 http://www.manormodels.com/main.sc to speeds over 350 Mph with the single antenna Optima 7 mounted inside the fuse. He did mount it vertically though.

I'd also do some power down range checks if you think there is a problem.

Mike.
Range check? Umm, I suppose I should have done that.

I've seen the recommendation to rebind a couple of times, but I don't understand why that would be a fix. Can the rx and tx achieve a partial binding?

In your range checks, have you ever had the rx antenna pointed directly away from the tx? I moved mine to a vertical orientation last night, so this discussion may be academic now. Thanks for your suggestions, Mike.

Dave
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Old Apr 02, 2010, 01:55 PM
Which shall it be, Passworthy?
Near Dallas, TX
Joined Jun 2007
2,495 Posts
Quote:
Originally Posted by A.T. View Post
whilst you would be most unlikely to see the receiver's blue LED flashing whilst flying, you may be able to set up on bench applying light load to servos whilst operating system


Regards
Alan T.
Alan's Hobby, Model & RC FAQ Web Links
reading your suggestion above, I had a sudden recollection! I remember hearing beeping. However, I thought it was coming from another flyer's system nearby (I have trouble distinguishing directionality of sound sometimes). Maybe it was the module's low voltage alarm.

If that is the case, then my ParkBec may be going bad, or possibly I have a servo somehow binding. Or an intermittent connection (I hate those). I don't recall anything unusual while storage-charging the battery. I certainly didn't run it anywhere near flat, more like 50%.

If today's rain doesn't produce a pond at the club field, I'll be out in the morning doing some more testing. Including a range check.

Dave
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Old Apr 02, 2010, 02:24 PM
Hitec/Multiplex USA
MikeMayberry's Avatar
Poway, California, United States
Joined Sep 2000
4,200 Posts
Then it was the BEC. This is the root of many crashes with 2.4ghz due to brownout.
The solution is to simply solder a servo connector (+/-) to the plug on the ESC and plug that connector into the SPC port. This will then power the RX independently with the main flight battery and the BEC will still supply the power for the servos.

Mike.
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Old Apr 02, 2010, 11:03 PM
Which shall it be, Passworthy?
Near Dallas, TX
Joined Jun 2007
2,495 Posts
Quote:
Originally Posted by MikeMayberry View Post
Then it was the BEC. This is the root of many crashes with 2.4ghz due to brownout.
The solution is to simply solder a servo connector (+/-) to the plug on the ESC and plug that connector into the SPC port. This will then power the RX independently with the main flight battery and the BEC will still supply the power for the servos.

Mike.
Thanks for taking an interest in my small problem, Mr. Mayberry. I was uncertain about using a separate connection to the SPC because of postings that indicated that it wasn't useful if you weren't using a separate battery for the rx. Most people don't put rx packs on 1 lb. foamies! In this case the presumed faulty BEC would be bypassed so the rx would be powered. The servos would suffer, however, and I might watch the still happily connected rx hit the ground with the rest of the plane.

Assuming that there was indeed a low voltage event, and the rx was bound in scan mode, how long does it take to regain control after V bounces back?

Dave
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Old Apr 03, 2010, 12:19 AM
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MikeMayberry's Avatar
Poway, California, United States
Joined Sep 2000
4,200 Posts
Once power is regained in any mode control should be restored almost instantly. It's only at start up that Scan mode takes longer to initialize.

The Optima RX's can draw similar power to a servo so when taking it out of the BEC loop you also take some load off of it as well.

I pretty much use the SPC always now for electrics as it just another layer of protection that does not hurt you. For example... in my Merlin I have (4) digital HS-5055 servos on an old MPX BL-17 ESC that has a 1.5A BEC. If I ran it like normal with the BEC powering both the RX and servos, when I moved all the servos quickly it would brown out. I then just tapped a servo connector off the ESC plug for the SPC so the BEC only powers the servos and I have 20+ flights on it with no issues. If I were to have flown it with the standard set up (or on any other 2.4ghz radio system most likely) it would have crashed on the first flight.


Mike.
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Old Apr 03, 2010, 07:05 PM
Which shall it be, Passworthy?
Near Dallas, TX
Joined Jun 2007
2,495 Posts
Thanks for the clarification, Mr. M.

I went to the club field this morning and flew the plane with the antenna in its new location (mounted vertically, poked through the right side horizontal fuse plate). I did see a minor recurrence of the aileron behavior (plane not seeming to respond enough to right ail input), but I'm thinking now that is was never a radio problem. It may not be a problem beyond inexperienced observation.

I did notice, last night while resetting failsafe positions, that one of the batteries I use in this craft wasn't initializing the ESC, even though I had charged it a few hours before. This same battery may well be the one in use when I first experienced my trouble. As then, a different battery did not show the problem. So, I probably have a batt that won't hold voltage, or other electrical problem, but the chance that any of this was caused by the rx is down to a choice of slim or none. And I think I saw Slim leaving town last week.

Thanks for everyone's attention. I think we can put this one to bed.

Dave
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Old May 17, 2010, 11:12 PM
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Mystery crushes

Quote:
Originally Posted by MikeMayberry View Post
Then it was the BEC. This is the root of many crashes with 2.4ghz due to brownout.
The solution is to simply solder a servo connector (+/-) to the plug on the ESC and plug that connector into the SPC port. This will then power the RX independently with the main flight battery and the BEC will still supply the power for the servos.

Mike.
Hi, Mike,

I recently switched to Aurora 9 from 72Mhz. My first flight day with my Wild Stik 46 was great, I was impressed with the radio. However, on the second day, after I took off I felt that I did not have enough controls, for example to make a simple left turn, I had to give full aileron and rudder input at the same time. I attempted to land the airplane but it literally fell out of the sky on the approach. I am not a very experienced flyer but I have never had a problem with simple approaches. So, the Wild Stik is a total "write off".

At the time, I blamed it on the weather, it was a little more windier than usual. But a couple of days ago I took up my Katana EP with a brand new Optima 6 rx. Flew a couple of circles, everything was fine. I tried to do a loop and the airplane never came out of it, it just spiraled down to the ground.

At this point, I am not sure what to do. I can't trust the Aurora anymore...

Both times I did range checks and everything seemed to be fine.

What did I do wrong? What would be your suggestion?

Thanks,
Sergei
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Old May 17, 2010, 11:20 PM
Hitec/Multiplex USA
MikeMayberry's Avatar
Poway, California, United States
Joined Sep 2000
4,200 Posts
It sounds like a brownout... did you follow the suggestion by using the SPC as described earlier in this thread? What servos and ESC did you use?

Mike.
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Old May 18, 2010, 09:03 PM
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Quote:
Originally Posted by MikeMayberry View Post
It sounds like a brownout... did you follow the suggestion by using the SPC as described earlier in this thread? What servos and ESC did you use?

Mike.
Thank you for the response, Mike,

I was using a 30 amp ESC with a 2A BEC built in with 4 hitec mini servos (55s). Today, I called the customer service at Hitec. The technician suggested the same thing - brownout. Unfortunately, I was not aware of a possibility of brownouts, so I did not research it prior to using the radio. That was a lesson taught the hard way.

The question about my Wild Stik with a glow engine still remains. The customer service rep could not guess what might have happened to the radio/receiver or if that could have been caused by something else. So, the mystery why I could not control the airplane still stands. On that airplane I was using my old 4.8V NiCad pack. It was fully charged with voltage around 5V. I used regular size Futaba and Hitec servos on it. The strange thing is that I flew it a couple of days before with a great success. The airplane was responsive with no indication of any problems. But the day I crashed it, it felt like it did not have enough throws of the control surfaces. Before taking off everything checked out fine, I am pretty sure of it.

Mike, can you please suggest any possible reasons for what happened?

During the crash, the plastic piece from the tip of the receiver antenna broke off, and now when I am checking the range in power down mode, I can't get my 100' that are required for a successful range check. I think, if that piece on the tip of antenna is so crucial for the receiver, it could have been protected (cased in).

Thank you.
Sergei
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Old May 19, 2010, 08:45 PM
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Sergei pretty hard to diagnose radio issues in a forum.

Hitec service is second to none - sent the stuff in, they will check it all out for you and fix or replace anything that is broken. They rock.

Mike
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