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Old May 14, 2012, 09:27 AM
Always Fly 2 Mistakes High!
RGS2010's Avatar
Houston, Texas
Joined Mar 2010
3,646 Posts
RX Troubles

Sorry to hear about your crash Kurt...I had one of my own!

I had landing gear problems taxiing on the ground...every time I ran up to near full speed it turned right quickly and one time hit a post very softly but apparently enough to unseat the nose wheel servo. SOOOOOOO...

I retracted gear and decided to hand lauch it. It just didn't seem to have enough power to launch but all you guys attested to the fact the it does (I have V1).

Well, I hand launched with the help of a club member and it flew off with authority, smooth and effortlessly. I got it up to about 75 feet, made a right turn and then it never completed the right turn...it went straight up to about 100 feet (no control of model) and then did a hammerhead turn and headed straight down. I was working controls feverishly but nothing happening. At about 50 feet it "flinched" and pulled up just a hair and then nothing again and went nose first into the ground hard. When I found it in the field, about 50 yards out from the runway, All controls were working and the battery was, of course, connected and unharmed. The carnage (I didn't take pictures) looked almost exactly like the nose of Kurt's except my tail boom section is completely intact (fiberglass mesh with epoxy held up) but the nose broke in half and broke the "supercharger" sections on top of each wing section although the wing was intact. Otherwise the boom sections were in good shape.

I probably won't rebuild it since it will take too much time. I only paid $39 for the airframe back with BH had it selling for that and I have another project or two in the works.

Bigger Issue: I was flying with Spektrum DX6i with DSM-X with a real Spektrum AR-600 DSM-X receiver. I have had a few DSM-2 "brown outs" but never on a DSMX. I was really confident in DSMX until yesterday. It was so obviously a radio problem. I flew two other planes after the crash and they perfored flawlessly...one with an OrangeRx and one with same kind DSMX rx that failed.

I was worried about how the RX was crammed into the middle section of the P-38 with all those wires. My ESC's were in the booms not in the center section.

Not sure if I just had a bad RX (it was brand new from LHS) or ???

Might be looking at Futaba now???

Russ
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Old May 14, 2012, 12:27 PM
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Kurt's Avatar
United States, TX, Houston
Joined Sep 2003
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man that sucks... sounds like a similar failure to the one described by Z8RC, but he was using a DX8.

found another casualty of my crash - one of the rudder servos is stripped. Amazing that the rudders aren't damaged at all... luckily ordered a few extra HXT900s so I've already replaced that one, and also done the first glue of the fuse crack with CA. Will go over on the inside with epoxy, maybe with a bit of CF reinforcement.
Also the nose gear door is cracked but still in one piece, some minor CF reinforcement will fix that nicely.
Thinking about sanding down most of the plane (to identify any other cracks that could use surface repairs), filling in the nose crunching, and painting silver. Now's the time to do it.
Also one of the motor shafts was slightly bent from my crash. Bent it back so it's very close to spinning true, but thinking about upgrading to 3mm shaft versions like on the V2.
Anyone upgrade the motors on their V1? What did you use?
This seems to be the 1150kV size that's on the V2, but what type of mount would you use?
http://www.hobbyking.com/hobbyking/s...dProduct=18160
I'll definitely put the props back on mine and see if the one that I tried to fix spins true before spending $50 upgrading.
thanks!
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Old May 14, 2012, 01:10 PM
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rdeis's Avatar
United States, CO, Colorado Springs
Joined Aug 2003
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RGS2010, were you using a stand alone BEC, or working from the ESC built in BECs?

The first place I'd go looking after a DSM lockout is a drop in voltage to the Rx, and there are a LOT of servos in this airplane...

Another cause could be the ESC placement, as you noted. My dad had a recurring failure in his SA Stick with one of those orange brick recievers and eventually traced it to ESC interfearance at certain attitudes. He moved the ESC-to-motor wires and hasn't had a problem since.
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Old May 14, 2012, 01:58 PM
Always Fly 2 Mistakes High!
RGS2010's Avatar
Houston, Texas
Joined Mar 2010
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Yes, I had two opto ESC's and a HK 5 amp UBEC (BEC). I used a 40C-3S-2200 Zippy lipo freshly charged.

If I had it to do all over again...I would use a RX with a remote satellite at least.
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Old May 14, 2012, 09:43 PM
If it's to be, it's up to me.
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Sydney, Australia
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Quote:
Originally Posted by RGS2010 View Post
Yes, I had two opto ESC's and a HK 5 amp UBEC (BEC). I used a 40C-3S-2200 Zippy lipo freshly charged.

If I had it to do all over again...I would use a RX with a remote satellite at least.
Given that you were using a large capacity, separate UBEC it sounds like your problem was not a brown out as you suggest, rather a signal loss. There is a big difference to those two failure modes and should not be confused.

I'm guessing a range test may have indicated a problem before you flew? Jamming a small rx into a tight space with lots of other wires is a sure way to ruin rx antenna separation and diversity. If you can't get a clean install, definitely a satellite is the go. Shame to have had to learn the hard way.

Sub
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Old May 15, 2012, 08:45 AM
Always Fly 2 Mistakes High!
RGS2010's Avatar
Houston, Texas
Joined Mar 2010
3,646 Posts
Sub,

Exactly right...poor choice of words on my part...because I still had a good connection to RX with steady light. Although I'm not sure how the DSMX rx's indicate "brown outs" like the DSM2 did I still think they flash, dont they after a brown out. Mine wasn't.

I do think it was a reception issue due to magnetic fields but outside of putting the RX on the outside of the plane...what are you guys doing about those mass of wires in the center section?

I'm drowning my sorrows in building a 70mm F-86 Sabre. You can bet the rx will be miles away from wires in that cavernous fuselage!

Russ
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Old May 15, 2012, 08:54 AM
Hey Guys, Watch This.......
mike2663's Avatar
USA, TX, El Paso
Joined Dec 2003
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Quote:
Originally Posted by RGS2010 View Post
Sub,

Exactly right...poor choice of words on my part...because I still had a good connection to RX with steady light. Although I'm not sure how the DSMX rx's indicate "brown outs" like the DSM2 did I still think they flash, dont they after a brown out. Mine wasn't.

I do think it was a reception issue due to magnetic fields but outside of putting the RX on the outside of the plane...what are you guys doing about those mass of wires in the center section?

I'm drowning my sorrows in building a 70mm F-86 Sabre. You can bet the rx will be miles away from wires in that cavernous fuselage!



Russ
Russ FYI from the Spektrum Website. It doesn't provide a answer to the issue.

"»Brownout Detection - Not Available on DSMX Receivers

DSM2 receivers feature Brownout Detection that flashes the receiver's LED if a power interruption occurs. While DSMX receivers have QuickConnect and recover instantly from a power interruption, the architecture of DSMX prevents Brownout Detection when operating in DSMX mode".

Mike
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Old May 15, 2012, 09:38 AM
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Owatonna MN 55060
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Quote:
Originally Posted by RGS2010 View Post
Sub,

Exactly right...poor choice of words on my part...because I still had a good connection to RX with steady light. Although I'm not sure how the DSMX rx's indicate "brown outs" like the DSM2 did I still think they flash, dont they after a brown out. Mine wasn't.

I do think it was a reception issue due to magnetic fields but outside of putting the RX on the outside of the plane...what are you guys doing about those mass of wires in the center section?

I'm drowning my sorrows in building a 70mm F-86 Sabre. You can bet the rx will be miles away from wires in that cavernous fuselage!

Russ
I use a AR6100 receiver in each boom. Mount them on top of the wing under the hatch. Lots of trouble free flights on both of mine this way.
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Old May 15, 2012, 10:10 AM
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United States, CA, Sunnyvale
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Quote:
Originally Posted by Gohmer View Post
I use a AR6100 receiver in each boom. Mount them on top of the wing under the hatch. Lots of trouble free flights on both of mine this way.
How do you bind 2 AR6100s to 1 model?
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Old May 15, 2012, 10:18 AM
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Owatonna MN 55060
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Originally Posted by vhuang168 View Post
How do you bind 2 AR6100s to 1 model?
They both need power and bind plugs, then you push the bind switch and turn on the transmitter after it's set to the model memory you want. Works with my DX-7.
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Old May 16, 2012, 05:49 PM
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United States, TX, Houston
Joined Sep 2003
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Humpy dumpty is back together again, stronger even.

Since ~1/4 of the elevator "hinge" was separated and the elevator was cracked almost through, I cut it entirely off and installed 4 du-bro hinges as well as epoxying a strip of 1x3mm CF right down the middle in a trench cut with an Xacto knife.
Did the same on the top of the main wings in an existing panel-line, which REALLY stiffened them up. They run from almost the wing tip all the way through the engine boom to about 1 inch inside the main fuse.
Ugly, but it should really tie her together.
Also cut a hatch in the belly to reinforce the main wing joint with a strip of basswood to prevent flexing.
Think I'll mount the satellite receiver back here as well, well away from the servo wires and main receiver.


Question - where are you guys getting pushrods online when you switch over to stoppers?

Tower and Hobbypartz doesn't sell 10"+ lengths of 1.2mm rod that I can find.

LHS only had 0.050" rods (which works out to 1.22mm, but they are a bit too big for the 1.2mm snap links I got on ebay: http://www.ebay.com/itm/360400173652...84.m1952.l2649 and also the 1.2mm stoppers http://www.hobbypartz.com/79p-5007.html

I ordered some of these 160mm x 1.2mm pushrods, but the rudder ones need to be ~7" long so have to find something else
http://www.ebay.com/itm/230429360286...84.m1497.l2649

BTW The servo horns hole and control-arm need to be slightly drilled to fit the stoppers, leaving a very small amount of material around the hole. Are you fortifying the horns in anyway to guard again breaking them?

thanks! She's ready to try for the skies again, once I get the control surfaces hooked up. Jpower really could have included spare clevis in the box without breaking the bank....
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Old May 16, 2012, 10:47 PM
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United States, TX, Houston
Joined Sep 2003
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found answer to my question on replacement motors here:
http://www.rcgroups.com/forums/showp...postcount=4427

One of my 2mm motor shafts is indeed bent, shakes like crazy over 25% throttle. Off to find new motors...
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Last edited by Kurt; May 16, 2012 at 10:56 PM.
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Old May 17, 2012, 12:26 AM
If it's to be, it's up to me.
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Sydney, Australia
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I replaced mine in a similar fashion. Post about it here: http://www.rcgroups.com/forums/showt...3#post20578559
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Old May 17, 2012, 08:28 AM
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United States, TX, Houston
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Originally Posted by subsonic View Post
I replaced mine in a similar fashion. Post about it here: http://www.rcgroups.com/forums/showt...3#post20578559
Thanks Sub! Still using the stock V1 ESCs?

Appears that HK has the market cornered on <$20 (Turnigy) motors, and the couple that have been used here (3536, AerodriveXp SK-3530-1100kv) are OOS.

How did you go about choosing that motor? W, kv and physical size of can, shaft length?

Hobbypartz seems to have some in stock, but I've overwhelmed by all the choices...
this one? http://www.hobbypartz.com/86ma66-2215-1050kv.html

HK has a TON of choices in stock, but not sure which one would be 'best' with the stock ESCs and 2200mAH, 3s battery (350W? 400+W? Don't know how powerful the stock motors are. Might as well go a little stronger).
http://www.hobbyking.com/hobbyking/s...idCategory=520

edit: searched this thread some more and found numbers reported between 150-300W for the stock motor, so 350W-ish sounds like a good number for a replacement.
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Last edited by Kurt; May 17, 2012 at 10:34 PM. Reason: added motor
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Old May 18, 2012, 11:26 AM
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United States, TX, Houston
Joined Sep 2003
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went ahead and ordered a couple Turnigy Aerodrive SK3 - 3530-1150kv :
http://www.hobbyking.com/hobbyking/s...dProduct=18160

Pretty pricey, but who knows when the cheaper ones will be back in stock.
From the specs they should be a bit more powerful than stock V1, about the same weight, and 1mm larger shafts

Specs:
Turns: 28T
Voltage: 3~4S Lipoly
RPM/V: 1150kv
Internal resistance: 0.069 Ohm
Max Loading: 24A
Max Power: 330W
Shaft Dia: 4.0mm
Weight: 76g
Motor Plug: 3.5mm Bullet Connector
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