How to destroy your best plane in one easy lesson.

[Flanker .]

Ok. It has taken me around three months to get over this. I am sharing it in order to perhaps save some one else's model.

 

So. With a large aircraft like my (ex) YAK and a large petrol engine one needs perforce to be extra careful safety wise . So I would check EVERYTHING before each flight, clevises, charge, bolts, hinges, the lot.

 

On the fateful day I had not had a weather / time window for a long time and had just enough time to get a fly in before going out. Great. Anxious for some new fly cam footage I took that along too. So careful check, all good. Canopy on (four fiddly bolts) fire her up - oh forgot to put pilot bear back in, never mind I don't ALWAYS have to have a toy bear in the seat - I CAN fly myself, so fire her up power checks, n off. Now dear Alex has pointed out that planes try to tell you that you have beeped up, and mine did. She dead sticked. The DLE 30 NEVER dead sticks, odd BUT I wanna fly. Go home and CHECK? No Wanna fly OK so off again and what a flight, I have been moving the pack back to find the sweet spot and this is THE sweet spot, wow. Really my best EVER flight with my best EVER plane. Now I had looked at poor Pilot Bear on the ground. And after the dead stick I got as far as taking one canopy bolt out in order to replace him, but no, no time. If ONLY I had looked more closely !

 

Vertical climb now using the power and feeding in rudder and elevator for a oh so sweet vertical tail, flick roll thingy - and - what is that ? I thought I saw a flash of something come off the plane - but nowt is falling and then ... oh god she's on her back and I have NO CONTROL wigggle nowt, Oh help, No NO she's going in! So flick the kill switch. Nothing, a 30cc powered plane on half throttle is now in an inverted dive and I have no control. The worst feeling ever, only had it once before long ago. Not my YAK not my best plane ever, not my new DLE. OH no No No. I watched her fall behind some scrub and just prayed that there had been no one underneath.

 

Post Crashum - No one dead. Thank god for that. But What, what could have failed ? The pack was a couple of meters from the wreck but all else was in the hole. Plugging it in revealed full working gear. Great , an intermittent fault in the radio. Not only a total loss but I have to send off working radio. Only consolation. She hit into sand and the motor looks ok. Flycam is in tiny little pieces. What caused this ?

 

Next day I got it. I had been moving the batt pack back to find the sweet spot so it had no strap but that was fine because it could not move sideways due to packing and it couldn't move up because of ... Pilot bear who sat on it with his head in the canopy thus fixing the batt in place. If I had put the bear in I would still have the plane. One little slip. The high G had flicked the batt out of its seat. The thing I saw fall off was a piece of the canopy, shattered as the pack flew around in the cockpit un plugging itself in the process. So a nasty nasty shock and a lesson learned.

 

I hope the above may help others to avoid a similar accident. I now have put the gear and motor into a spare YAK and we will see what is what when the grass on the patch is short again. I don't mind telling you that this was one of the biggest confidence knocks that I have ever had .

 

Go well dear all. Flanker.

PS Pilot bear is talking to me again after I fixed him up with a new plane and locked in battery.

[Tim Mackey]

Oh dear, sorry to read that Flanker - and uncannily like the sad tale that BEB relayed about his BEBbit a few days ago.

[Erfolg]

Sounds similar to my own little incident. I wrote about it in the "Weathers improving........." thread.

 

In my case the, the canopy was held in place by a rear, turnbuckle type latch, relying on friction to maintain position and an elastic band near the front. The rear friction catch worked loose and the elastic band acted as a rubber hinge.

 

I my case the battery escaped whilst bunting, unplugging it from the Rx, ESC. The battery fell to earth, to be found 5 days later.

[Ben B]

I can understand why you're a bit upset. Try not to be too hard on yourself though, these things happen occasionally. Nasty feeling though, one of my planes did something similar and it took a while for me to realise I had absolutely no control over it as it decended at speed.

[Steve Hargreaves - Moderator]

Flanker I am sorry for your loss....but as you say hopefully it may prevent a similar issue occuring in someone elses plane.

 

In the fullsize world they have a system of anonymous reporting of accidents & incidents with the aim of alerting other pilots to a potential issue with their aircraft. I think the forum does a similar job. I wonder how many people have read of an "incident" & then thought..."Oooh I'd better check that on my aircraft..." I know I have....!!

 

You do raise an interesting point though....how often do we just hold a battery or such like in place with a bit of foam or some sticky tape & then proceed to throw our models across the sky pulling God knows what "g".....that 4 oz battery pack weighs 1.5lbs at 6g & I bet our models pull a lot more than that......still think a bit of foam will hold it in place??

 

And of course with bigger models weights increase so a typical 3300 Nimh battery weighing around 8 oz suddenly gets to 3lbs at 6g....Gulp!!

 

This issue occured to me recently when installing a 16ox tank in my latest (90 powered) model.....when full thats 1lb of fuel.....at 6g thats 6lbs!!! At 10g thats 10lbs....more than the whole aeroplane weighs at rest!!! Bloomin' heck I'd better make sure thats strapped down then.

 

Recently a newcommer turned up with his trainer & the battery & Rx weren't fixed in at all....when this was mentioned he said it would be OK....gravity would keep them in place.....quickly inverting his fuselage convinced him that gravity isn't always his friend!!!

[Ben B]

Good point. I'm rather OCDish nowadays about canopy / battery fixings after the battery on my Zagi exited the plane rather quicky during a bunt taking with it the ESC, the receiver and the propeller. I found the plane but the above and the canopy are still MIA somewhere. The new battery is well and truly fixed in place and the replacement canopy is secured with a wing bolt through the canopy top into the fuselage at the back and hinged at the front with glassfibre re-inforced tape so even if the battery wiggles loose it's not going anywhere in a hurry.

[Alan Cantwell]

a hard lesson, many commiserations

 

and another thing, the strain on things like extension leads, how many of us do anything about stopping them coming apart, well, after losing a model a couple of years ago, i secured them, but it was a tad cumbersome, now, i have found, from ripmax, a superb easy to use widget, i will try to find them, and post back,

 

one thing i cannot find, and i am running out of them, is a tag, that velcros to the fuzz side, and the wire passes through an eye, these i use for stopping wires beating the fuselage to death, anyone any ideas?

[David Ashby - Moderator]

The only consolation is that you know what caused it and can learn from it. There's nothing worse than never being able to establish the cause of a crash - you can loose trust in your radio and your own flying skills and confidence goes a long way where the flying is concerned.

 

 

 

[Myron Beaumont]

Flanker

Sorry to hear of your loss

Interesting about G forces isn't it? Never really thought about it before( like most of us I suspect) I'm pretty sure that because of your experience .a lot more of us will make sure it doesn't happen, even if it wasn't the cause .Steve said it all regarding G forces .Wow!

We live and learn from every one else don't we .That's life

[Tim Mackey]

No apologies for cross posting this , but this is what I use for battery retention on any model over a few pounds in weight.

I posted on BEBs crashed BEBit thread but seems it might be useful to spread the word around a bit more.

 

I recommend you use a "proper" Velcro strap such as that shown in the picture. It loops over the battery, and through the buckle - like a proper belt, and then back on itself to really grip very well indeed.

This - coupled with some Velcro on the battery and tray should mean nothing shifts unless you want it to.. Here is a belts and braces twin strap that I use on the big PC9.

Available from several model shops, and some DIY sheds too.

PS I also use a strip of self adhesive on the battery and tray too, to stop slip.

Edited By Tim Mackey - Administrator on 16/06/2011 18:50:27

[Myron Beaumont]

Timbo

As a novice to lipos I'm tempted to ask "Wouldn't the buckles cut through the battery containing plastic stuff that keeps it together in the event of a sudden arrival" From your experience this is not the case . Something else I / we have all have learnt today .

[Tim Mackey]

Nah, they are fine Myron. I have had a couple of badly damaged Lipos in recent months following severe crash damage ( one on Saturday actually in a mid air at the PSSA ) and they were fine. I wont use them of course, but they present no hazard unless the actual case is punctured and very high currents are allowed to flow.

[Josip Vrandecic -Mes]

Dear Flanker ,I'm really sorry ....I have no words..

[Biggles' Elder Brother - Moderator]

Sorry to hear about that Flanker - as Tim says I have fresh experience of how you feel - full of "if only's"....

 

Still we accept it as part and parcel of what we do don't we? Shed a few tears , curse and swear a bit , raise a glass or two in memory of the glorious departed , then move on in search of the next blue horizon, a little older and hopefully a little wiser.

 

BEB

 

 

[Vecchio Austriaco]

Flanker,

 

Be carfull with bears - they have their own ideas. The guy in the picture destroyed an Edge 540 EP in December 2009 over Italy and got a second chance.

Same plane different field: April 2011 - Made a knive edge which was toooo low and what you see on the picture is all what is left.... You can immagine the G force as the bear weighs almost nothing...

 

To be ,more serious: Fixing the battery is extremly important as it is the heaviest device in the plane. This is even more valid for electrics. Too all: look that there is nothing in the way of the battery which could damage it in case of a crash. Had a crash once where the engine screws were too long and pierced the Lipo - the plane was in a cloud of grey smoke in seconds. The lipo - if pierced - burns like a firework! And as the ESC is close to it you know what will be ruined next. How do I know that ?

Edited By Vecchio Austriaco on 16/06/2011 23:48:31

[Alan B]

Hi

 

In addition to using velcro straps to hold the lipos/batteries - all my batteries have a strip of self adhedsive velco running the complete length of the battery - usually the hook part as it is more ridged and the loop part as it is more flexible in the model. This ensures that there is no movement of the battery if things work loose. I find lipos are slippy things and will still slide through the retainers/straps under certain conditions.

 

Al

[Tim Mackey]

The title for the new section is now done, and this thread is just one of several in that section, and has probably now run its course - I'll clean it up a little.

[Steve Hargreaves - Moderator]

Tims velcro straps are a good idea. I quite like & use release-able cable ties lots available....see here which perform the same function .

 

@Alan C....might a self adhesive cable tie base be suitable? Again lots available here. I've also seen some made of thin alumium sheet which have a self adhesive backing & are cut to form two prongs which you can then fold around the wires to hold them in place.....personally I don't like them as I think the ally might abrade the wires & cut through the insulation with the airframe vibration....if you took steps to avoid this issue though they might be a good solution...

[Tim Mackey]

I used to have box of those little aluminium ones you mentioned - used em for tidying cable runs in PC chassis etc - they were great, and worked out very cost effective. Cant seem to find them these days. CPC do have a large range of the re-usable straps eh Steve - just off to order now

[Steve Hargreaves - Moderator]

CPC are brilliant Tim.....part of the Farnell group they are just up the road from me & I use them all the time. I commend them to you!!!

 

Lots of bits & pieces for the modeller....glues, electronic components, plastic bolts for holding your U/C on. cable ties, batteries, tools, soldering irons, flat screen TVs....all at excellent prices!!! The best model shop you've never heard of....

 

Ooops...off topic....

[Bob Cotsford]

I found some of the self-adhesive tie bases at B&Q, and they also do the velcro and other straps in the gardening section. TBH it's the only reason I would ever have for going anywhere near a gardening section

[Tim Mackey]

Oh I know them well enough for electronic components Steve - had an account woith em for donkeys years....just never thought of them for velcro straps

"Farnell online" I think my bookmark is.

[Kozmyk]

Velcro straps are standard fare in the RC heli world, from fastening Lipos to ESCs and Gyros.

Here's a page full of them for you.

Fast Lads - Hook & Loop straps

 

Regarding self adhesive velcro to stop slippage, I find that just a strip or two at one or each end is enough to stop slippage and not so much that a lot of force is required to undo.

 

Edited By Kozmyk on 17/06/2011 12:02:17

[Flanker .]

All good advise. Thanks. I think the real point here is that I changed my restraint (bear) inadvertently. So each thing needs to do its job so that changing or leaving out doesn't affect other systems. I knew the bear held the battery in but forgot. Bear and batt should have been discrete so that forgetting bear did not affect the battery fixing.

 

The only plus is that we will see how the rebuilt YAK goes.

All this is less stressful if you do not suffer from church mouse syndrome !

 

Ah well.

 

go well dear friends. Flanker

[Peter Beeney]

Flanker, I can really empathise with your misfortune. Like many others, I’ve dinged a model or two and it really does hit hard when it’s your best and most expensive aeroplane. I was very sorry to read your story. I suppose one consolation, if you can call it that, is the fact that you have a perfectly rational explanation for it, I’m sure it would be ten times worse if it were some obscure and untraceable radio fault, say.

With the greatest respect, and I sincerely hope you won’t mind me saying this, but one little situation that can arise is that even without the battery flying around in the model the battery plug can manage to disconnect itself from the switch harness socket. I’m sure this is a very rare occurrence, but I do know it’s happened, I have seen it, at least twice that I can remember. On another occasion I saw the battery fall out of the open cockpit of a bi-plane whilst it was in flight and inverted, but not for long, and a mate saw the same thing at another site. So as a consequence of all this I make no apologies for repeating once again in these posts that for the more adult beginners I advise that it’s a good idea to tie the plug and socket together, and for the younger members it’s mandatory. One of only a very few things that are.
I use string tied long ways round the socket, though the wires. I’m not quite sure that insulation or masking tape is fully up to the job, and as I’m used to lacing twine it seems the obvious thing… Purely a personal preference.

I can remember reading in the mag, a long time ago, about someone whose Christian name was Dave, I think in Ireland, who designed and flew aerobatic models, and also wrote articles for the magazine. One story he related was how the battery fell out of the model, I can’t remember why that was, but he had tied the plug and socket together so the battery stayed with the plane so that he could land it. I struck me at the time that my stance on this was thus fully justified!

I also seem to remember he went on to build a very large scale model, I think it might have been a Hercules, there was a list of materials, which included 10 jars of PVA glue, just for starters………..

There is one more battery story. A long time ago, again, a beginner built a large model, I think it was a DB Hannibal, or some such name, a high winger. Another lad flew it around on it’s first flight, and on the way in to landing went round a nice gentle loop. The model touched down and was trundling down the runway when the pilot said “I haven’t got that!”. We set of in pursuit and managed to catch up before it got to the far hedge, which was fortunately quite a long way. On examination the battery was lying in the bottom of the fuselage, disconnected from the switch. The builder had made a really nice job of it, and because of the vast interior, had constructed a nice neat ‘pocket‘ on the fuselage side, which the battery exactly fitted into. In those days we only ever seemed to have the standard 500 mAh square pack nicads. What he had forgotten, and with the ever easy hindsight, most importantly, was to put a lid on it; and we concluded that the battery had just slid out of it’s container at the top of the loop and the little bump of touching down was sufficient to then pull the battery of the harness!

Sometimes you can get lucky…….

PB