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Old Mar 16, 2012, 04:51 PM
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United States, WA, Duvall
Joined Mar 2012
38 Posts
Question
Diagnosing a maiden voyage crash

Hey guys,

I did a maiden voyage with my recently built EPP FPV today. The first flight went relatively well until I lost engine power what seemed like half a mile from my take-off spot. It was probably 15 minutes in to the flight so I'm guessing I ran out of battery. Since it was the first flight, I wasn't sure what to expect out of the pack I'm using...

Here's a video with most of the flying cut out. Fast forward to 2 minutes if you want to see the power failure and seemingly endless glide home. And who said EPP FPV's can't glide?

EPP FPV Maiden Flight (2 min 58 sec)


The second flight didn't end so well. At some point the plane stopped responding to my controls. It ended up in a death spiral from several hundred feet. It's salvagable but I'm bummed.


I'd like to rule out the transmitter and ESC as causes. I'm running a Futaba 9C with a new 9 channel PCM receiver.


A couple of questions...

Is the battery meter on the front of the Futaba 9CAP reliable? It was showing 9.9 volts at the time of the crash which seems reasonable. If I wanted to get a new battery for a 9CAP, where's the best place? I generally don't like to buy batteries on Ebay as you can't tell if they're really new.

On the initial flight when it shut the motor down the ESC was beeping some codes. You can hear them in the video. The ESC manual doesn't list any of the error codes so I'm not sure what to make of it. I'm not sure it had anything to do with the second flight failure and crash.

I'm off to glue some foam.

Thanks guys,

Aaron
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Old Mar 16, 2012, 07:37 PM
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Daemon's Avatar
Lakewood, Colorado
Joined Aug 2002
28,474 Posts
Looks like a 2-3 hundred yards out, not a half mile. That plane glides like the space shuttle.

Anyway, I'd bet that you overloaded your ESC or ESC's BEC, killing power to the Rx.
This plane uses *a lot* of power to go anything other than really slow, and it'd be easy
to under-spec the ESC.

ian
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Last edited by Daemon; Mar 16, 2012 at 07:45 PM.
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Old Mar 16, 2012, 07:51 PM
Registered User
United States, WA, Duvall
Joined Mar 2012
38 Posts
Ian,

You might be right on the distance. I'll use Bing maps to measure it sometime. It sure felt far when the engine went dead.

Yeah, I'm wondering about the ESC and BEC. It's a 50 amp ESC with a 3 amp BEC. I wasn't running anything but the receiver and four small servos onboard so I'd be surprised if I overloaded the BEC?

Here's the specs on the motor:

2814-06 Motor
Li-Po Battery: 2 / 3 cells
Max Current: 40A / 60 sec
Weight : 100g (3.52oz)
Watt Range: 230W - 350W
Kv: 1450
Recommended Model Weight: 1,000 - 1,900g (35oz - 67oz)
Recommended Model Prop: 3 cells Li-Po : 9.5 x 5 (Approx 40oz of thrust)

And the ESC:

Weight: 50g (1.7oz)
Size: 46 X 35 X 8 mm
Battery Input: 2-3LIPO
Throttle Calibration: Auto
Constant Current: 50A
Max Current: 65A / 10 Sec
AUTO CELL DETECT!!!
BEC: 3Amp
Timing: High
High rate Switching: 8k
Voltage cutoff: 3.0V A Cell Li-Poly 0.8 NiCd/NiMH
Brake: Programmable On/Off
Auto shut down when signal is lost
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Old Mar 16, 2012, 08:04 PM
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United States, TX, Mansfield
Joined Jan 2012
527 Posts
Quote:
Originally Posted by AaronHartwell View Post
Hey guys,

I did a maiden voyage with my recently built EPP FPV today. The first flight went relatively well until I lost engine power what seemed like half a mile from my take-off spot. It was probably 15 minutes in to the flight so I'm guessing I ran out of battery. Since it was the first flight, I wasn't sure what to expect out of the pack I'm using...

Here's a video with most of the flying cut out. Fast forward to 2 minutes if you want to see the power failure and seemingly endless glide home. And who said EPP FPV's can't glide?


http://www.youtube.com/watch?v=mpdJnWuwoPk

The second flight didn't end so well. At some point the plane stopped responding to my controls. It ended up in a death spiral from several hundred feet. It's salvagable but I'm bummed.

I'd like to rule out the transmitter and ESC as causes. I'm running a Futaba 9C with a new 9 channel PCM receiver.


A couple of questions...

Is the battery meter on the front of the Futaba 9CAP reliable? It was showing 9.9 volts at the time of the crash which seems reasonable. If I wanted to get a new battery for a 9CAP, where's the best place? I generally don't like to buy batteries on Ebay as you can't tell if they're really new.

On the initial flight when it shut the motor down the ESC was beeping some codes. You can hear them in the video. The ESC manual doesn't list any of the error codes so I'm not sure what to make of it. I'm not sure it had anything to do with the second flight failure and crash.

I'm off to glue some foam.

Thanks guys,

Aaron

Sorry to hear about your crash. Of course as I'm sure you probably know all too well (just like the rest of us) that it happens even to the best of us sometimes. At least it's salvageable, and not a total re-kit. Trust me, that is no small thing! (again, I'm sure you know this already)



The batt meter in your 9cap should be quite accurate assuming nothing is damaged/defective, etc. Still, you DO ALWAYS charge your TX before you go out to fly, right???

I do, even if I am 100% sure it is not needed. If it's been more than 24hours since I touched that TX, it goes on the batt charger before I fly with it. NO EXCEPTIONS.

I am not quite so anal about land vehicles, tho. But I digress...


How many series cells are you running? If above 3s, the BEC in your ESC will be VERY unreliable most likely.

Even at 3s, I wouldn't trust it with my RC gear. Spend $15-$30 and get a decent stand-alone power supply for your RC gear. That is always my recommendation...


Also, if you don't have one, you should think about getting a watt/amp/volt meter. There are several brands out there that look similar, and most work quite well.

If you have that you will not have to guess how long your flight battery will last. You will be able to calculate it with reasonable precision.

Good luck!
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Old Mar 16, 2012, 08:22 PM
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United States, WA, Duvall
Joined Mar 2012
38 Posts
Hey CTvxL,

Thanks for the response! Yeah, I'm glad it's repairable. Glue is drying as we speak. I ran out of the Goop glue I've been using and had to switch to Weldbond. Hopefully it sets up OK on the EPP.

I do generally charge my radio between flights. Because this radio is new to me I went ahead and cycled the transmitter all the way to zero and did a full 18 hour charge (per the manual). I think it was fully charged.

Good catch on the battery. I should have listed that. It was a 3S 5000 mah LiPo from HobbyKing. Notice I said "was". The impact smashed the end in.

I have four 2S 5500 mah LiPo packs. The motor says it will run with 2S. I'm hoping I can use them. If not, I'll order another 3S pack or two.

A standalone power supply for the receiver sounds like a good idea. Are we talking about a receiver pack? Or an external BEC?

Voltmeter also seems like a wise investment. I'll see if I can find one.

Thanks again!
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Old Mar 16, 2012, 09:26 PM
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United States, TX, Mansfield
Joined Jan 2012
527 Posts
Quote:
Originally Posted by AaronHartwell View Post
Hey CTvxL,

Thanks for the response! Yeah, I'm glad it's repairable. Glue is drying as we speak. I ran out of the Goop glue I've been using and had to switch to Weldbond. Hopefully it sets up OK on the EPP.

I do generally charge my radio between flights. Because this radio is new to me I went ahead and cycled the transmitter all the way to zero and did a full 18 hour charge (per the manual). I think it was fully charged.

Good catch on the battery. I should have listed that. It was a 3S 5000 mah LiPo from HobbyKing. Notice I said "was". The impact smashed the end in.

I have four 2S 5500 mah LiPo packs. The motor says it will run with 2S. I'm hoping I can use them. If not, I'll order another 3S pack or two.

A standalone power supply for the receiver sounds like a good idea. Are we talking about a receiver pack? Or an external BEC?

Voltmeter also seems like a wise investment. I'll see if I can find one.

Thanks again!
Welbond: Never used it myself. Also never glued EPP so I can only stand back and say, "good luck" as I have no idea about those things


I'm sure your radio was charged and good to go. The Futaba 9 series is a very nice radio and is usually VERY reliable. I LOVE my 9CHP!!!!!! Better radios do exist, but this one is a keeper IMO. I've had mine for a few years, and wouldn't sell it today, even for twice the price I paid for it (second-hand btw. It came with a helicopter I purchased from a guy who wanted out of the hobby)


Have you done a proper range check? Do you know how? (please don't be insulted by this ?)




Watt Meter: I have one of these, and I LOVE it. It's TINY and failry accurate. There are many similar devices, and most work equally well: http://www.western-robotics.com/inspector_hp.html


You connect it BETWEEN your LIPO pack and ESC (yes, there will be some small loss, but not too much for taking measurements)

It tells you exactly how many amps the system is pulling, etc. It also records max watts, amps, volts, etc. You can take it up in your plane, fly it full throttle for several seconds, land, then check to see max watts, etc. VERY useful...

Of course, you can also use it to test other conditions other than full throttle such as cruse watts, etc. It gives you a lot of very valuable information for a thing that really does not cost very much...

It's the next best thing to OSD with current meter (and costs A LOT less in most cases)




Stand-alone power supply: Could be battery pack or stand-alone BEC or voltage regulator. Batteries are heavy, so most use a BEC.

Top of the line according to many is the Castle Creations BEC. I don't own one myself, but I don't think I have EVER read anything but glowing praise about it. EVERYONE who owns one says it was well worth the price from what I have read.


However, any good quality stand-alone BEC should be fine.


hth,

Charles T.
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Old Mar 17, 2012, 12:41 AM
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United States, WA, Duvall
Joined Mar 2012
38 Posts
The wattmeter looks pretty slick! I'll probably end up ordering one. It would be nice to take some of the guesswork out of the equation when it comes to battery life, power usage, etc.

I ran a Castle BECs on one of my electric helis. It was nice. It made my ESC run quite a bit cooler.

The ESC I ordered for this plane was supposed to include an external 5 amp BEC but Grayson Hobby sent me the wrong ESC with an onboard 3 amp instead. I blame them for my crash. Not really.

I'll look into an external BEC or battery pack tomorrow at my local hobby shops and pick something up. I've wanted to have a receiver pack around to have when checking receivers, servos, etc, so I might go that route.

I don't think I know how to do a proper range check honestly. I've heard you do the check with the antenna down but that's about all I know. I'll do some searching to see what I can find.

Aaron
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Old Mar 17, 2012, 01:10 AM
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Joined Sep 2011
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this is why it is very nice to record the video with the OSD info, showing voltage and amps

It's how I figured out I had some bad batteries (from eBay - will never buy batteries form eBay ever again!

I run a similar power setup on my EPP FPV, no problems, though I fell the ESC I have is more robust than a typical ESC - it is a Turnigy DLux 55A, running a 3536-5-1450, w 9x5 prop and 3500 3S. And I am ripping it all out to put in a Zephyr2

15 minute maiden - bold! I usually keep it to 5 min.
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Old Mar 17, 2012, 01:36 AM
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United States, WA, Duvall
Joined Mar 2012
38 Posts
BC - Yeah, I'm looking forward to having OSD data. I forgot to turn on the camera on the second flight where I crashed or I would have engine / ESC noise to go on. Dumb...

Good to know that your set-up worked with a similiar config though i agree, your ESC is probably better. I'm going to follow Charles advice and seperate power to the receiver.

Zephr2, nice! If this thing ends up getting cracked up again such that I can't repair it I think I'll go for a wing as well.
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