Battery ejection - bad crash

[Tony Kenny]

Hi all,

I'm sharing this photo of my pride & joy after the battery was ejected whilst pulling out of an outside loop after performing various other high-G manoeuvres. Turns out velcro is quite reliable, but, the self adhesive backing is really weak! Battery came out leaving me with no control!

Future plan: 1) more secure battery mounting, 2) a small lipo backup for rx & control so I'll at least have control if this happens again.

I'm also considering some sort of latch on the battery connector so the weight of the battery cannot pull it out.

[Chris Walby]

Tony, commiserations for your loss and yes you are spot on when it comes to checking the Velcro baseplate is fully attached especially after lots of flights. While fitting a battery on my Carbon Yak I noticed the end of the tray lift a bit. Further investigation and it came out with little difficulty (originally glued in with silicone sealer).

IMHO I would change battery fixing system/prevent the Velcro detaching and leave it at that.

UBEC and lipo add complexity and weight and one day you might want to disconnect the lipo very quickly without undoing the locking system.

PS My Wots wot tray fell out (yes there are people that have never had this issue, but when its does) and before I landed the lipo disconnected from the EC5 connector, the massive change in C of G would have probably made it un-flyable anyway.

[Peter Miller]

I always stick my non self adhesive Velcro down with epoxy. Had too many self adhesive Velcro come adrift.

I lost my Super 60 when the battery came out in aerobatics. This time the whole mount came loose after a rought field take off. Well, there isn't much structure to stick the mount to.

RIP

[Ben B]

Not sure if this is the problem but self adhesive Velcro is really bad at sticking to foam. A really effective trick is to glue a thin ply / balsa plate onto the foam then attach the Velcro onto that. The velcro will hold onto the wood much better. An alternative is to smear the foam with epoxy- again the Velcro will bond much better.

[Tony Kenny]

HI All,

Some good advice thank you.

Ben, I agree, it's not great on foam at all. My plan is to do the same as I did on the glider which was to use the double sided velcro that sticks to itself and glue that to the fuz so it's nice and secure. For this model I'll probably do that in 3 places and also consider adding an additional 'gate' by way of a piece of balsa under a couple of clips to just slot in place.

I am a bit surprised that ARTF models don't tend to have any form of battery mount whatsoever and even those that do tend to be inadequate. The canopy of this one also had such weak magnets that it fell off the first time I flew inverted, which prompted me to add velco to that too.

We live and learn, but it will be a while before I get time to fix this.

[trebor]

Evostik Impact contact adhesive

Ps test foam first or use Por Uhu 

Edited By trebor on 29/09/2018 09:43:15

[Capt Kremen]

Commiserations and sympathies Tony.

My MaxThrust 'Ruckus', (recently reviewed here too!), has suffered a not dissimilar fate.

The LiPo secured with two(2) strong velcro straps around the pack passing thru the fuselage so no sticky to come unstuck. Then the magnetic top canopy/hatch, lip engaged on the front so slipstream forces it down and can't get under to blow off - hmmm or so I thought!!!

I'd been successfully flying the aircraft for numerous flights, including the usual sports aerobatics of loops, rolls, stall-turns, inverted etc. all with the battery securing arrangement and position as described above, no issues. After the usual pre-flight safety checks including pulling both velcro straps tight around the Lipo, taxied out to the runway.

After a steady, straight ahead take-off, a very gentle bank to the left, away from the flight line, (of course!), was commenced. Hardly established in the turn, canopy/hatch flew off and the LiPo ejected itself. With no power, the airframe spun in, exit one aircraft as a write-off!

Moral of this tale - Don't totally rely on velcro or magnetic hatches, even in very gentle, non-aerobatic flight.

[Tony Kenny]

Yep, we've become too reliant on convenience and these easy answers are just too tempting! I'm annoyed with myself because I was concerned that the battery wasn't properly secure but it had been OK in all flights for the past year so didn't so anything. That was my mistake, I should have gone with my gut and done something, especially knowing that each time I remove the battery I'm pulling on that velcro and the weak adhesive beneath it!

I'll submit this photo to RCME too, maybe somebody else can learn from my mistakes.

To make matter worse, i also ripped the motor mount out of my FW190. The u/c got damaged and other club members suggest just hand launching and belly landing and the prop would knock out of the way. Unfortunately, a couple of these landings knocked the prop but pull the motor mount out. Thankfully, that's an easy fix, but I wonder what damage these landings will eventually do to the motor shaft. I've bent enough on other model already. The moral again, fix the thing properly!

[trebor]

Posted by Capt Kremen on 29/09/2018 10:20:26:

Commiserations and sympathies Tony.

My MaxThrust 'Ruckus', (recently reviewed here too!), has suffered a not dissimilar fate.

Capt, would you say the Ruckas would have been a keeper ? I keep looking at it and my pockets are burning !

[Ron Gray]

UHU Por is excellent at providing a really strong adhesion between Velcro and the surface it’s applied to, but it must be applied as per the instructions, in other words, coat both surfaces, let it go touch dry and then stick together. I have found that the longer it is left before sticking together the better, I once forgot about one until the next day, then stuck them together, no problem and one of the strongest joints I’ve made with it!

[Stuphedd]

My rule is over 1000 3s use straps to secure and vecro to stop the lipo moving .!

I have actually had 1000 3s break through the bottom of the fuz due to excess very high G aerobatics as well as frequently loosing rudders when pulling out of "Blenders" !!! (same plane )!

[Trevor Crook]

Another vote for velcro straps. Never had a problem with them, and it's easier to peel a strap apart than it is to lever out a "velcroed" battery, which of course stresses the adhesive each time.

[Capt Kremen]

To reply to Trebor - Mmmm ... it was OK but, IMHO, had lots of imperfections, as said 'down to an (expensive) price, not necessarily up to TOP quality'. If purchasing again, would get basic airframe, no motor, servos or linkages and improve U/C, axles, wheels, LiPo & canopy retention AND add a missing pilot in that canopy!.

[Don Fry]

Sympathy, but unless the ejected flight battery was on the centre of gravity, when it went a battery supply to the receiver won't have saved tou. The trim shift will be severe, and or it will still be uncontrable. Don't trust glue, it always comes off.

[onetenor]

A blind (pop) rivet or two will hold Velcro to a ply plate (add in a washer for additional support if you feel the rivet might pull through) Glues can fail in a couple of ways.Especially if they get hot. Even sunlight can do it particularly if repeated as in a shed in strong sunlight. Exposure to heat from radiators/convector heaters etc. Contact cement glues/cement can go powdery or if exposed to fuel goes soft and gooey. Any solvent based glue can be subject to this. Por types go glass like and brittle and shatter with a sharp knock or vibration. So if your model is old check all joints carefully.Even Velcro's adhesive can and will dry and go powdery (OR GOOEY) sooner or later

[Keith Berriman]

Hi all. I find that Velcro branded name own self adhesive 2" wide from Amazon sticks like ????? and difficult to remove when needed to

[Shaun Walsh]

Posted by Capt Kremen on 29/09/2018 10:20:26:

Commiserations and sympathies Tony.

My MaxThrust 'Ruckus', (recently reviewed here too!), has suffered a not dissimilar fate.

The LiPo secured with two(2) strong velcro straps around the pack passing thru the fuselage so no sticky to come unstuck. Then the magnetic top canopy/hatch, lip engaged on the front so slipstream forces it down and can't get under to blow off - hmmm or so I thought!!!

I'd been successfully flying the aircraft for numerous flights, including the usual sports aerobatics of loops, rolls, stall-turns, inverted etc. all with the battery securing arrangement and position as described above, no issues. After the usual pre-flight safety checks including pulling both velcro straps tight around the Lipo, taxied out to the runway.

After a steady, straight ahead take-off, a very gentle bank to the left, away from the flight line, (of course!), was commenced. Hardly established in the turn, canopy/hatch flew off and the LiPo ejected itself. With no power, the airframe spun in, exit one aircraft as a write-off!

Moral of this tale - Don't totally rely on velcro or magnetic hatches, even in very gentle, non-aerobatic flight.

Hi Capt

There's a mod for the Ruckus on the Century UK web site

https://www.centuryuk.com/images/Max%20Thrust%20Ruckus/ruckus%20addendum.pdf

Looks like canopy ejection may be not uncommon, perhaps if you contact Century you might get a discount on a replacement.

Edited By Shaun Walsh on 29/09/2018 16:40:34

Edited By Shaun Walsh on 29/09/2018 16:45:40

[Biggles' Elder Brother - Moderator]

I only use straps now, anchored to something I put in with hard backstop etc., which in turn is securely attached to the main structure. So unless we get catastrophic structural failure, in which case it's all over anyway, that battery ain't going anywhere.
BEB

[Engine Doctor]

+ for Straps passing around or through fuselage .

[Peter Miller]

Just something to consider.

I have an Eagle Tree G meter.

I did a test with an i.c. model, a long full power vertical dive and maximum up elevator pull out.

The recorded G was 24.8g. which meant that the model weighed about 95 lbs at pull out

Oh yes, the model was fine afterwards.

[Phil 9]

here is my take and it echo's some comments above

I use stick on Velcro to stop the battery moving back and forth and use a strap to tie it down. or I have used foam pieces glued in to make a battery tray to stop lateral movement

I guess you could wrap Velcro around a battery and attach it to itself so it wont un-stuck but I much prefer to fix the strap to the body of the model

Edited By Phil 9 on 30/09/2018 17:34:28

[Mark Greer]

May I add I think this very much depends on how much you are prepared to pay for velcro tape.

I bought some today that cost £7.00 a meter not just cheap stuff from the local model shop.

The Glue is Ultra strong and the velcro is very strong and could support a lot of weight.

Now I,m only a sports flyer for now owning a Extra 300 eflite 1.3 meter but when I decide to start serious 3D I will not regret it.

When flying 4S 3900 mah lipo that pack a punch and cost nearly £60.00 its worth paying the extra for the little things .

Hope this advice helps happy flying

[Frank Skilbeck]

If you want something really strong then the 3M Dual Lock is really good, don't use too much though or you may never get your battery out again!

[Nigel R]

I use straps that loop through a buckle and then velcro back on themselves, there's no moving those under high G.

[Richard Clark 2]

Posted by Peter Miller on 29/09/2018 09:03:34:

I always stick my non self adhesive Velcro down with epoxy. Had too many self adhesive Velcro come adrift.

I lost my Super 60 when the battery came out in aerobatics. This time the whole mount came loose after a rought field take off. Well, there isn't much structure to stick the mount to.

RIP

Me too. And a lot of 'supermarket' velcro is only available self-adhesive but it comes off with cellulose thinners. And epoxy can 'peel' so I also put a couple of countersunk screws through it. Velcro is fine otherwise, even for big batteries (in my case a Kilogram in an EDF) if you have a large overlap. Alternatively put a loose loop of the two sorts of velcro sewn together with 'button thread' passing UNDER the battery platform

As for BECs etc. I only use them on small low value/low effort planes. I would rather larger planes carry three or four ounces of Eneloops for the radio than have zero control.