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Old 09-29-2007, 04:17 PM
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WM T-34 crash. Spektrum to blame?

Nice day so I thought I would fly my T-34. I had about 3 good flights. I noticed me flight pack was low. Put it in the quick charger and then its ready in about 20 min. Took off and was doing some high speed passes. On the final turn, the plane get turning and went upside down and went it full throttle inverted. What happened? I don't think it could have locked out because it was at full throttle.The plane is totaled. All bits of balsa now. The receiver was even broken in the crash along with my rudder servo. It could be the spektrum or the rudder servo stripping in flight and making it go in.
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Old 09-29-2007, 05:19 PM
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Re: WM T-34 crash. Spektrum to blame?

did you have any failsafe setting?like low throttle.if you did and it went in at full throttle i bet your rudder stripped out hard over
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Old 09-29-2007, 05:38 PM
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Re: WM T-34 crash. Spektrum to blame?

My fail safe was set to go to idle.
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Old 09-29-2007, 05:44 PM
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Re: WM T-34 crash. Spektrum to blame?

When you say it went in full throttle, do you mean you tried bringing then throttle back but it did not work ?

Albert
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Old 09-29-2007, 05:49 PM
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Re: WM T-34 crash. Spektrum to blame?

No, I didn't move the throttle. I was more occupied by the fact that my plane is turning and I'm not telling it to do that in the split second before it went in.
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Old 09-29-2007, 08:34 PM
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Re: WM T-34 crash. Spektrum to blame?

ya know, sounds like to me the battery pack would be a good place to start here. since it didnt go to failsafe. i doubt that it is the radio, although most are quick to blame that first.
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Old 09-29-2007, 09:34 PM
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Re: WM T-34 crash. Spektrum to blame?

I'm sure I'm going to get flamed over this... but... I have heard of 5 crashes like this locally that make me suspicious of the component quality of Spektrum/2.4. Assuming your power system is/was good and your servos did not lock up you may have just had a component failure. I'd send the RX in to have them check it out anyway.

I have had a Spektrum TX go bad and had the board replaced. Prior to that I had a bunch of good flights on big gassers but just before it failed I had some very wierd mushy control response. Luckily I did no lose a plane over it and the board was replaced.

I'm not bashing 2.4 - I think the technology is probably sound but I'm not convinced of the quality of the components. My flying buddy also had a TX go bad when his was new. I don't know what the failure rate is on 72mhz stuff... don't get me wrong I have seen some 72mhz mysteries this season too. It could be that you see more Spektrum's going in due to a combination of "normal" component failure and a likely some power systems are not up to the task which is a valid and known issue.

I had a mystery one myself 3 weeks ago. Flying a 25% 40cc Edge, the batteries were freshly charged and tested (2600mah LiIon), the regulator is capable of 10amps sustained, it only had 5 digital servos ... all of which combined could not draw 10 amps. I actually took someone up in the plane on the buddy box because he wanted to buy it. He said land it and I'll write you a cheque. Just before turning on to final the airplane did 2 uncommanded snaps and then a big KE loop into the ground. It never went to failsafe and I had no control what so ever as it flew by itself for 45 seconds at least. Luckily only the airframe and RX were a write off. The RX was intact but not working... which is probably why it crashed and never went in to failsafe. I took the carnage to my garage, plugged in a new RX, bound it and everything worked fine. The battery load tested fine, the regulator worked fine under load...

Last weekend one of the most experienced flyers I know lost a King Kat jet on a 9303 X or whatever the 2.4G version is called. He had a Powerbox and ample batteries too... it never went to failsafe, it just flew away and crashed (luckily it didn't fly far or hit anyone/anything.)

Personally I can't trust it in big planes and no one at my home field is using it any more except on small electrics. I still use mine on smaller electric planes and EDF Jets up to 3S 2200mah size... with no issues (assuming you keep the BEC voltage high enough.) I figure when the Futaba FAAST system (the 8 and 14 ch version) comes out I'll try again since I'd love to be immune to shoot downs.

Just my 2c... keep in mind that the VAST majority seem to have no issues at all. You could have just been unlucky and got a bad Rx... the same thing happens (rarely) on 72mhz. Lots of people had problems on Futaba PCM G3 when it came out too... For me PPM / PCM FM works great and the only issue is getting shot down (which luckily where I fly is very rare.)
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Old 09-29-2007, 11:04 PM
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Re: WM T-34 crash. Spektrum to blame?

My flight pack was 5. something volts under load. So I have taken that variable out. Crhammond, I think you may be right about the quality issues. But will spektrum cover the broken receiver? It was damaged in the crash. But the thing that gets me, is that someone elses plane went down in the same area using a futaba 9z with a 2.4module. Coincidence? or something is weird at our field?
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Old 09-30-2007, 12:35 AM
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Re: WM T-34 crash. Spektrum to blame?

What I don't get is that nobody stops using 72mhz when they have unexplained problems...

People continue to use it on small electrics because the potential loss is smaller, or an out of control electric is less dangerous than a large model?



Quote:
Originally Posted by crhammond View Post
Personally I can't trust it in big planes and no one at my home field is using it any more except on small electrics. I still use mine on smaller electric planes and EDF Jets up to 3S 2200mah size... with no issues (assuming you keep the BEC voltage high enough.) I figure when the Futaba FAAST system (the 8 and 14 ch version) comes out I'll try again since I'd love to be immune to shoot downs.

Just my 2c... keep in mind that the VAST majority seem to have no issues at all. You could have just been unlucky and got a bad Rx... the same thing happens (rarely) on 72mhz. Lots of people had problems on Futaba PCM G3 when it came out too... For me PPM / PCM FM works great and the only issue is getting shot down (which luckily where I fly is very rare.)
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Old 09-30-2007, 12:45 AM
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Re: WM T-34 crash. Spektrum to blame?

CRG, people still use 72mhz when they have problems because they understand how to fix the problems. We're still figuring out how to work around the problems with 2.4ghz. Hell, when I called Horizon about the voltage issue back in Feb they told me that it is wasn't an issue. Quique proved them wrong.
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Old 09-30-2007, 08:13 AM
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Re: WM T-34 crash. Spektrum to blame?

Quote:
Originally Posted by CRG View Post
What I don't get is that nobody stops using 72mhz when they have unexplained problems...

People continue to use it on small electrics because the potential loss is smaller, or an out of control electric is less dangerous than a large model?
I get your point... I'm still using it in my small electrics because I have not had any 2.4 problems in them. I have only had problems in gassers. I don't own any glow planes so I can't speak to that.

Who knows, maybe it's vibration or heat related?

I know plenty of people who HAVE ditched 72mhz to go to 2.4... I was one of them. Early in the season I was hooked and had quite a few trouble free flights. When I started having problems I went back to 72mhz ... for exactly the reason dubd said, I know how to work around RF issues in gassers etc with 72mhz. I learned those lessons the hard way too. When a gasser passes a range test on 72mhz flawlessly, has a good power system and is correctly soft mounted, I have never had a problem... I guess I have not had any 72mhz Rx failures.
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Old 09-30-2007, 08:40 AM
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Re: WM T-34 crash. Spektrum to blame?

What size and voltage is that battery, if you just charged it the peak voltage is pretty high and it can make servos do some crazy stuff. My buddy has a 10x with spektrum and in his jet with a full charged battery (6 volts, peak at 7.2) the aileron servos wont work. If you have low resolution servos a high voltage through the spektrum RX can screw with some stuff.
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Old 09-30-2007, 09:17 AM
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Re: WM T-34 crash. Spektrum to blame?

I fly in a small club 3 guys are flying 2.4 in glow and electric planes. Between them they have had 2 receivers quit one in flight. 2 of the guys have had blown fuse problems with their transmitters none while flying. The receivers were sent in and replaced by horizon. I know you guys will say 72mhz has the same problems but in 4 years of flying i have not seen anyone have a problem with 72mhz. We fly in a remote area so we don't have interference like a lot of you guys that fly near the city may experience. Our club is growing and i personnel was shot down by a beginner so i am anxious to change over myself just sitting on the fence right now. These guys are still flying their DX7s. I think the quality issue that crhammond mentioned may have merit
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Old 09-30-2007, 10:25 AM
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Re: WM T-34 crash. Spektrum to blame?

My battery was a 600ma 4 cell. We tested it after the crash and it read 5.2 volts.
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Old 09-30-2007, 10:39 AM
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Re: WM T-34 crash. Spektrum to blame?

Were you using dual switches and back up battery supply????Check your switches....Six thou for a plane and ten bucks for a switch....Redundancy is the secret...
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