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View Full Version : My First Crash - R.I.P. Easy Star


Sam_K
10-14-2007, 06:08 AM
Today I was at the club field and had just passed the "15 hours in the air" mark on my Easy Star (I log all my flights). I was waiting for my battery to recharge and friend at the club says "Hey wanna borrow my spare 3S LiPo?".

Now normally I run a 2S LiPo in my Easy Star with the stock speed 400 motor and a 14A ESC. My calculations have it running at around 6-8A. I know a 3S LiPo is too much volts for a speed 400 motor but I figured if I stayed at half throttle or less it shouldn't matter too much and the ESC shouldn't have any trouble. Besides if I shorten the life on my motor it just means I get to do that brushless upgrade sooner.

So I popped the battery in, checked my CG balance and went to the flight line. I launched the plane and everything seemed fine and I kept the throttle low and didn't go outside the usual "performance envelope" that I get from my 2S.

About 1 minute into the flight the motor suddenly goes to full throttle. I have no throttle control anymore! I turn the plane around to bring it back towards the field and onto final. I yell out "Stuck at full throttle!" to everyone else on the flight line. Then about 10 seconds later I lose all radio control and the Easy Star suddenly pitches into a vertical dive at full throttle and plunges into the deep, bushy valley just beyond the field.

I race off to the fire trail that leads into the valley. At this point I know the model is gonna be in a very bad way, but I am scared that if the throttle stays on full that it might catch on fire and then set the bush on fire!

When I find the model it is smashed to pieces. The speed 400 is still going flat out but the spinner and prop have come off and it is just spinning the shaft so it's not hot enough to burn anything. I pull the plug and start picking up the pieces.

After returning to the field we survey the damage. The tail has been ripped off which has broken the servo arms and then pulled the push rods through the guides causing the Z bend to rip the guides to shreds. The elevator is snapped in two.

The entire top part of the wing seat has broken off and the motor wire has ripped away half of the inner surface. The motor mount is broken and half of the upper part is missing. This is the only piece of the model I did not find.

The wing spar is badly fractured and has about 8 long lengthwise cracks along it. One wing is all torn up on the underside near the root. I think the wing foam actually exploded outwards as the spar bent whilst it was inside the wing.

The nose is bashed in and split open, though not enough to open up the battery bay.

I already knew just from the sequence of events that it must have been the ESC that went bad, causing me to lose throttle control at first and then causing loss of power to the RX. Another modeller at the field said that when ESCs let go it's usually because the bit that carries the main current load gets so hot that the solder melts. I inspected the ESC, it stinks of burnt electronics, and sure enough i can see gobs of solder "splashed around" under the heat shrink casing.

Oh well, lesson learned, it was my own dumb fault for not knowing the 3S + Speed 400 was too much for the 14A ESC.

Even if I could glue all the foam back together reasonably straight, a lot of the hardware was ruined and would need replacing. The cheapest way to replace it would be just to buy another ARF kit and then I might as well use the fresh new foam bits in it too. So this is a total write off.

Here are the pics...

:(

Note in the picture of the CF wing spar I am bending the rod with my hand to make the the fractures open up so you can see them in the pic.

Sam_K
10-14-2007, 06:17 AM
I just checked the RX and servos using an RX battery and they are working fine. Phew! Really glad the ESC did not kill my Spektrum AR7000 RX and/or servos or the repair bill could've been more like $350 (Australian) instead of the $140 I am looking at presently.

Airhead
10-14-2007, 08:24 AM
Sorry to hear about your crash Sam. :( Time to start a rebuild and some new electronics.. Keep us posted..

max2112
10-14-2007, 08:57 AM
I just checked the RX and servos using an RX battery and they are working fine. Phew! Really glad the ESC did not kill my Spektrum AR7000 RX and/or servos or the repair bill could've been more like $350 (Australian) instead of the $140 I am looking at presently.

Sam,
I like your "glass is half full" attitude! :tc:
I say use this as a reason to get that next plane on your wish list! Did you have any replacement airframes in mind?

Jkc123
10-14-2007, 09:49 AM
So that might not have happened if your friend had given you that bat.......hmmmm! Sorry bout your plane though!! :{

Sam_K
10-14-2007, 10:42 AM
Sam,
I like your "glass is half full" attitude! :tc:
I say use this as a reason to get that next plane on your wish list! Did you have any replacement airframes in mind?

Actually I do! Since I got back from the field I've been researching what to do about getting another plane in the air.

Lately I had already been thinking that I had learned all I could from the Easy Star and I've been thinking more and more about an aileron trainer.

So far the Ace Simple 400 (http://www.wattflyer.com/forums/showthread.php?t=19236) is looking like a winner!

The fact that it is really cheap to buy, is stocked by one of my local hobby stores, is powered from a Speed 400 like the Easy Star and uses similar servos means that it's probably the cheapest option currently available to me.

AEAJR
10-14-2007, 01:20 PM
That plane does not look all that badly damaged. Nothing there a little CA can't fix. 2 hours tops.

Of course you will need to replace the motor and ESC, but other than that, I would have probably fixed most of it at the field.

FlyingMonkey
10-14-2007, 01:48 PM
Hot Glue!!!!!!!!!!!!

CHELLIE
10-14-2007, 09:14 PM
Hi Sam, I have done things like that too, knowing better, and I do it anyway :ws: oh well, time to upgrade to a brushless, use a 30 esc in all of your planes, it wont have to work so hard and get hot, and that will never happen again, thats what I do, and have never had a problem with a esc, you control your amperage with the battery, 10c 15c 20c etc, the lipo will only deliver what its made to do, the esc does not control amperage, its just rated at what its max usage is, take care , Chellie

Ps That Ace Plane looks nice, you deserve it, No Matter what your wife says :)

http://www.acehobby.com/ace/images/airplane/ACE4244.jpg

Sam_K
10-15-2007, 02:59 AM
That plane does not look all that badly damaged. Nothing there a little CA can't fix. 2 hours tops.

Of course you will need to replace the motor and ESC, but other than that, I would have probably fixed most of it at the field.

Well now you've gone and made me feel like a wuss for not trying! :roll:

Seriously though, now that I've had some time to take stock and get over my grief I do agree that all the breaks are pretty clean and should glue back together without much trouble. The biggest task will be repairing the custom cover job.

I've ordered a new Tower Pro 2408-21 brushless motor and Mag8 30A ESC and I will fix up a custom motor mount for it. This motor should also be good for the Simple 400 when I do finally pull the trigger on that purchase (I may ask Santa to get it for me if the Easy Star repair goes well).

Do you think it is worth trying to use some epoxy to seal up cracks in the CF wing spar, or should I just buy a new one? Given that I am going for a stronger motor and I like to hoon around and do loops n stuff, I don't want a weakened wing spar giving up on me and causing catastrophic crash #2.

Hi Sam, I have done things like that too, knowing better, and I do it anyway :ws: oh well, time to upgrade to a brushless, use a 30 esc in all of your planes, it wont have to work so hard and get hot, and that will never happen again, thats what I do, and have never had a problem with a esc, you control your amperage with the battery, 10c 15c 20c etc, the lipo will only deliver what its made to do, the esc does not control amperage, its just rated at what its max usage is, take care , Chellie

Ps That Ace Plane looks nice, you deserve it, No Matter what your wife says :)

I would have thought that if you try to draw more amps than the battery can deliver then you would damage the battery and possibly cause a LiPo fire? Not sure, but that's what I always assumed.

My wife actually already approved of the Simple 400 purchase. We are going away for a 2 week beach holiday in 1 week's time and she knew how keen I was to get in lots of flying while we are away.

I decided to fix the Easy Star though cos I am a bit attached to it now. After spending so much time on it, I couldn't just chuck it in the bin. Besides I was also a bit dissapointed that I would not have the Easy Star around if any friends or family ever want to try their hand at RC flying.

CHELLIE
10-15-2007, 03:17 AM
Thats great that your going to fix up your easy star, if your going with a 3 cell with your 2408-21, a 8x4 prop will work great, that motor can take up to a 7x6 prop max on 3 cells, also add a extra carbon fiber tube, when you fix the wing, epoxy works great, and to fill in any gaps, mix a little epoxy with some lite spackle, 5 parts spackle to one part epoxy, works great, here are some prop specs from heads up rc, for the 2408-21 with a 2 cell and 3 cell, take care & have fun, Chellie

http://stores.ebay.com/Heads-Up-RC_Brushless-Motors_2408-21-motor_W0QQcolZ4QQdirZ1QQfsubZ4181263QQftidZ2QQtZkm

Propeller data for 3 cell Lipo batteries:
GWS props fit the 3mm shaft on this motor perfectly - no adapter needed. APC and Master Airscrew props require a prop adapter or prop saver for a 3mm shaft (available in my store).
The GWS EP8040 is the most commonly used prop with this motor. It will produce about 22 ounces of thrust at 14 amps with a pitch speed of 43 mph. This motor is only rated for 13 amps, so you need to provide for plenty of airflow over the motor and use full throttle sparingly until your Lipo has discharged somewhat.
The APC 8x4E produces 22 ounces of thrust at 14 amps with a pitch speed of 39 mph. The same caution must be used as with the GWS EP8040.
I do not recommend using any other 8 inch props with this motor when using a 3-cell Lipo.
The APC 7x5E produces 20 ounces of thrust at 14 amps with a pitch speed of 54 mph. The same caution must be used as with the GWS EP8040.
The GWS EP7035 produces 16 ounces of thrust at 9 ampswith a pitch speed of 47 mph.
The APC 6x5.5E produces 11 ounces of thrust at 10 ampswith a pitch speed of 65 mph.
The Master Airscrew 7x4 3-blade produces 15 ounces of thrust at 12.5 ampswith a pitch speed of 43 mph.
The Master Airscrew 6x4 3-blade produces 11 ounces of thrust at 9.5 ampswith a pitch speed of 48 mph.
Recommended props for 2 cell Lipo batteries:
The GWS EP1060 prop produces about 15 ounces of thrust at 11.5 amps with a pitch speed of 33 mph.
The GWS EP1047 prop produces about 15 ounces of thrust at 12.5 amps with a pitch speed of 24 mph.
The APC 9x3.8SF prop produces about 16 ounces of thrust at 11.5 amps with a pitch speed of 24 mph.
The GWS EP9047 prop produces about 14 ounces of thrust at 10.5 amps with a pitch speed of 27 mph.
The GWS EP9050 prop produces about 14 ounces of thrust at 10 amps with a pitch speed of 32 mph.
The GWS EP9070 prop produces about 13 ounces of thrust at 12.5 amps with a pitch speed of 35 mph.
The GWS EP8040 prop produces about 12 ounces of thrust at 7.5 amps with a pitch speed of 32 mph.
The GWS EP8043 prop produces about 12.5 ounces of thrust at 8 amps with a pitch speed of 31 mph.
The GWS EP8060 prop produces about 13 ounces of thrust at 10 amps with a pitch speed of 39 mph.
The GWS HD8060 prop produces about 12 ounces of thrust at 9 amps with a pitch speed of 41 mph.
The above data is a result of my own testing using fully charged Lipo batteries.
2408-21 Specifications:


Weight = 1.6 ounces (46 grams)

Diameter = 1.2 inch (31mm)
Total Length = 2.4 inches (62mm)
Shaft Length = 1.2 inches (31mm)
Shaft Diameter = 3mm (GWS Props fit nicely)
Voltage = 7.2 to 12.6
KV = 1750

Sam_K
10-15-2007, 03:58 AM
Thanks for the info Chellie, I have already been using the data from Heads Up RC to decide which motor to go with.

I currently have a 2S 2500mAh 25C LiPo that I would like to continue using for the time being. Eventually though I would like to standardise on 3S LiPos. I see this motor as a good compromise between 2S and 3S performance and it also fits the budget.

I am intending to make a raised mount for the motor on the Easy Star. By raising the shaft up 1" I can then fit an 8" prop and still clear the tail boom.

I know it's not the most ideal motor for the Easy Star but I am looking more to the future when I upgrade to the Simple 400 and 3S LiPos. Also I got the 30A ESC for even further into the future if/when I get a bigger motor.

CHELLIE
10-15-2007, 04:06 AM
Thanks for the info Chellie, I have already been using the data from Heads Up RC to decide which motor to go with.

I currently have a 2S 2500mAh 25C LiPo that I would like to continue using for the time being. Eventually though I would like to standardise on 3S LiPos. I see this motor as a good compromise between 2S and 3S performance and it also fits the budget.

I am intending to make a raised mount for the motor on the Easy Star. By raising the shaft up 1" I can then fit an 8" prop and still clear the tail boom.

I know it's not the most ideal motor for the Easy Star but I am looking more to the future when I upgrade to the Simple 400 and 3S LiPos. Also I got the 30A ESC for even further into the future if/when I get a bigger motor.

Sounds Good Sam :ws: thats what I do, I buy 30 amp esc, and use them on just about everything, I can use the 30 amp ESC on all the bell Towerpro motors, I have the 2408-21 great motor, the 2410-09 on a slow stick, 2409-12 on a Dr1 Fokker and getting in a 2409-18 for a pusher jet, I have had great luck with these cheapy little motors :D Take care, Chellie

Stan-the-Man
11-30-2007, 06:20 AM
Today I was at the club field and had just passed the "15 hours in the air" mark on my Easy Star... So this is a total write off.

Here are the pics...

:(

Note in the picture of the CF wing spar I am bending the rod with my hand to make the the fractures open up so you can see them in the pic.

A sad day at the OK Corral. You have my sympathy cause I'm a fan of the EZ*. I don't have one yet, but "I feel your pain". :sad:

Well, there's an old saying that I'm going by... everyone can call me what they will, but "if ain't broke, I'm not fixing it."

Sorry about your loss.

Happier landings.

flydiver
11-30-2007, 02:14 PM
Just a FYI, when you "over volt" an ESC and attempt to Keep things in control using throttle management you will have limited success. The whole voltage is still sent to the system just in shorter bursts (that's the switching the ESC does) AND it has to bring the higher voltage DOWN to the auxiliary level (servo, RX). The only way it has to do this is by making heat. That's why you can't run MORE servos with higher voltage systems (seems at first like you should be able to run more things with more voltage doesn't it?).

Also oddly, if you were "hot rodding" it, the motor would have been sucking more volts and the lipo would have "sagged" just a bit more making the ESC job of pulling the volts down for the other stuff a bit easier and it "might" have been OK-but unlikely since the EZ is so battery thrifty.

Rebuilding it will be a good experience. We all have to learn repair skills too. It's also a good reason to move on. You'll be doing that sometime anyway.

fly

guest001
11-30-2007, 04:23 PM
Jee, zus, Fritz, you are shaking early! Going to the field, today? It's mighty cold.

panzerd18
11-30-2007, 10:14 PM
Oh well, lesson learned, it was my own dumb fault for not knowing the 3S + Speed 400 was too much for the 14A ESC.

Not only that but a 3S is also too much for a speed 400 motor. It would have been better if the motor melted before the ESC, just unlucky.

flydiver
12-01-2007, 02:21 AM
Not only that but a 3S is also too much for a speed 400 motor. It would have been better if the motor melted before the ESC, just unlucky.

That depends of the 400. Some models last pretty well with 3S but it's hard to know which model you have unless you specifically order it and it would be unusual nowadays to do that with the number of acceptable cheap brushless replacements.

I agree with the motor melting sentiment. At least there would have been landing control.

fly

Captain
12-02-2007, 12:53 AM
I can vouch for the tp2408-21 motor as well. I run on one my F22 foamie and love it! The AUW is 9.5 and with a 2s it has all I need. They also sell extra shafts so if you bend one its nice to have a couple on hand.

RCairplane.pilot
12-02-2007, 09:47 PM
hi, did you tear your friends lipo up? be a drag if it puffs up when he recharges it, im by no means a expert, but im thinking maybe a radio"gilitch" instead of to much battery for ESC,"ive used 3S with 15A on speed 400 lots times before with no sweat," since you said you wasnt running WOT. but hard to say remember we dealing with cheapo eletronics made in china,lol. id repair it if you can, use it as your "range check" plane before flying the new planes you get

flydiver
12-03-2007, 12:13 AM
A glitch of that magnitude and manner seems very unlikely since he had just gotten done with his own 2S batteries in a field he was familiar with. Upon flying the 3S all hell broke loose. Coincidence? Doubt it.

It's REALLY common for people to push the "power" envelope in RC, either deliberately or through ignorance. Over propping, over-volting, too much motor (yes-you CAN have too much motor), and the reaction to frying an ESC-the next one is WAY big.

A really common one is to dork a Slow Stick geared system, (6:1 gearing, 11x8 prop on a 7-cell NiMh system), decide to do that cool brushless/lipo thing they read about on the internet. So they get a TP2408-21 (a relatively high revving motor only suitable for a 8x4 max prop and not the best option for the SS) and put the 11x8 on it, having a bunch of them since they were breaking them every 10 minutes while learning. Flies fantastic (or too much) for 3 minutes before burning up. One guy reported it did an immediate loop upon full throttle take off within 1/2 second and bashed back into the ground before he could even react.

fly

RCairplane.pilot
12-03-2007, 12:20 PM
hi, now that you mentioned it, im gonna put a $6 dollar 2410-09Y on a slow stick i just now bought for $10 bucks , with a GWS EP1170 prop an 3S 1250 lipo. should be a hoot to fly.

flydiver
12-03-2007, 03:34 PM
hi, now that you mentioned it, im gonna put a $6 dollar 2410-09Y on a slow stick i just now bought for $10 bucks , with a GWS EP1170 prop an 3S 1250 lipo. should be a hoot to fly.

Yeah, but that TP will handle the prop. I use that combo but generally a smaller prop.
fly

darylm44
12-03-2007, 05:20 PM
You will be glad you decided to repair your plane. I have an old wing dragon 4 and I am on my 3ed wing (really ate up the first two). It is nice to take it down and fly it first when I haven't been out to the feld lately. Helps to make sure I remember how to use the sticks with the plane coming at me.

flydiver
12-03-2007, 05:29 PM
You will be glad you decided to repair your plane.

Agree. There is something to be said for a plane that you don't have too much financial or emotional investment in. You are more willing to take some flying risks and maybe help other new fliers learn on it.
It wasn't so long ago that a broken prop on my slow stick was a minor tragedy. Now I barely flinch when it gets a new wing ding.

fly