AXN battery mount

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AXN battery mount

Postby mikem » Sat Aug 04, 2012 10:57 pm

I'm a beginning RC flyer. Am not part of a club or anything so I'm pretty much on my own with it.

Flew a Yard Stick 3-ch park flyer for awhile then moved to an AXN thanks to the RCMR and Xjet videos which I consider a great find.

The RCMR videos were *very* helpful in sorting out AXN details. Assembled my AXN as per suggested practice. All the advice on ESC's, batteries, and the like, were very good. With a 2200mAh 3s in the nose my AXN balances very well.

To build my confidence I did dozens of hours with the Hobby King FMS simulator. I found online some plane sim profiles (.par) somewhat close to AXN: "Hawk Sky", "Graupners Tipsy", and "EasyStar". No problem.

BTW, Anyone have a link to an AXN.par that will run on FMS?

Before I knew it I was flying loops, doing Immelmann turns, and actually landing where I wanted to land. I must have done 200 touch and go's, flew every plane sim I could get my hands on. FMS is great fun, especially for $15.00US!

Anyway after a week I thought I had made all the stupid beginner's mistakes flying FMS. I was especially wary of being overpowered with the AXN as I watched you folks flying them like jet fighters but I thought I was ready at last!

After a very short flight I crashed hard, stalling due to the battery shifting aft suddenly. Crunched the nose and cracked the fuse aft of the prop. Battery also took out the rudder servo arm.

Felt pretty wretched for a day looking at the limp crash victim on my dining room table.

Then, surprisingly, the crash actually cheered me up as if I had passed some kind of rite of passage. We can rebuild and make it better...

So I'm hoping you experts will give me some advice:

1. What's your advice on securing the 2200mAh LiPo? That's the main problem I think. There must be more G force on it than I expected. I had carefully cut just enough foam so the battery would just slide in with the aft edge flush to the end of the foam. Also I CA'ed a 1" velcro "belt" into the cockpit to strap the battery in putting about an inch of fuzzy on the top of the battery so it wouldn't slide. I'm really surprised it could move at all but it did. It felt pretty tight in there. There must be a better way to secure it.

2. Also can you recommend how to fix the split in the fuse behind the prop... in that skinny little winestem? In the RCMR videos Bruce talks about hot gluing the foam. Is hot glue gun glue better for repairs than the Chinese foam glue that came with the kit? Seems to me the fuse now needs some kind of reinforcement. It is cracked almost through back there.

3. The nose is pushed back a bit and split along the top. Should be able to glue it together. Any suggestions about stiffening it, making it stronger? Coat it with epoxy perhaps?

I bought two AXNs in my original order so I have a backup when I have beat this one to death... but I'm sure there's quite a bit of life left in her yet!

Really it is a wonderful plane and I am delighted with the whole project in spite of the present difficulty.

Thanks in advance for your help!

mikem

Mike McDade
Bangor, Maine US
maturin@roadrunner.com
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Re: AXN battery mount

Postby cynr100 » Sat Aug 04, 2012 11:40 pm

Welcome Mike,

That must have been one biffo, sounds like you had the battery well secured how sure are you that it came adrift in flight. Ground impact may have dislodged the battery as you have stated that the battery tookout a servo.
Half the fun in this game is building or rebuilding :D
Take some time out and read through this thread
viewtopic.php?f=54&t=1443
unfortunately it is not all business, lots of socialising taking place here but you will pickup some good "fix em right up" tips. I used some carbon rods to stop the fuselage from "bending" which translated the forces of impact into the nose area which is now utter toast.
The best idea for repairs is to "fly better and get some altitude" :lol: :lol: :lol: :D (sorry couldn't help myself :) )
My preferences are - hot water for restoring shape (freshly boiled water BUT don't stick it in boiling water) and the good old hot glue gun and tape.
Epoxy.......hmmmmmmmm.....one would need to be carefull the epoxy doesn't chew the foam up. It would also add weight plus make the fuselage rigid which is not going to be kind if you have a similar biffo, crush zones can be repaired whilst anything resembling glass is in the dust bin.
The split in the tail stem.......... carbon fibre rods (2mm dia) each side of the break and extending from middle of main wing to the tail plane, glue the crack and hold the rods in place with tape.

Hope this helps some and keep us informed as how you are going.

Cheers
Dennis :D

PS: Pictures are a great way to get your problems sorted plus we like to see carnage....... :lol: :lol: 8-)
Not enough time in the day for all my crazy ideas, I'm not slow, I'm just pacing myself
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Re: AXN battery mount

Postby mikem » Sun Aug 05, 2012 12:21 am

All sounds like good advice.

I take your point about getting aloft. I noticed that Bruce says elsewhere that FM simulators tend to act like the plane is filled with helium. I might have expected it to fly "heavier" than the sim, but that could be my problem.

I'm still puzzled about the battery. It seemed to have shifted aft not forward as in a nose dive which is what I expected. I suppose it could have rebounded on impact. I guess I'll add a second "belt" around it this time if that's all it needs.

I had not thought of using hot water for reshaping. Excellent idea!

The thread you suggest was useful. Will have to study how to lay in some CF rods to stiffen things a bit. Should do the trick.

Thanks a bunch!

mikem
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Re: AXN battery mount

Postby cynr100 » Sun Aug 05, 2012 4:01 am

mikem wrote:
I'm still puzzled about the battery. It seemed to have shifted aft not forward as in a nose dive which is what I expected. I suppose it could have rebounded on impact. I guess I'll add a second "belt" around it this time if that's all it needs.


mikem


Did she nose dive into the ground :?: if so that would be more than enough to unseat and "shift aft" the battery and break the tail boom.
I never strapped mine in, it was just jammed inside the nose between the foam with a velcro strip down one side of the battery allowing friction to hold it in place. I have smacked mine so many times I have forgotten but I never did loose the battery (its out of shape from all the impacts :P )
The battery would have to move a long way to upset the CG causing a loss of control, I'd be looking at airspeed, wind speed, atitude and stick inputs at the time.
Enjoy the rebuild and get her back up. :mrgreen:

Dennis
Not enough time in the day for all my crazy ideas, I'm not slow, I'm just pacing myself
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Re: AXN battery mount

Postby mikem » Sun Aug 05, 2012 3:12 pm

Hi Dennis,

I had a quick nose up, sudden stall, then plowed right into the ground before I could react. Probably I overreacted to the plane being heavier than I expected from FMS experience. The simulator is good news and bad, isn't it?

The battery must have pulled forward on impact and then rebounded aft. I can see that I gave the battery opportunity to torque around the single Velco patch on its top... in version two I'll put some fuzzy on the bottom as well.

I'm thinking of laying in a 2 or 3 mm CF rod maybe 180mm long, one on each side of the fuse break behind the prop.

I have a couple of "carnage" photos as soon as I can see how to post them... looks like I have to load them as attachments somewhere but I don't see how just yet.

Thanks for the good advice!

Mike
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Re: AXN battery mount

Postby mikem » Sun Aug 05, 2012 3:55 pm

Hi Dennis,

I think these carnage pix should come through okay:
DSC00593aj1.JPG
cockpit
DSC00593aj1.JPG (203.43 KiB) Viewed 3846 times

DSC00594aj1.JPG
nosejob
DSC00594aj1.JPG (154.01 KiB) Viewed 3846 times

DSC00595a2j1.JPG
fusebreak
DSC00595a2j1.JPG (116.09 KiB) Viewed 3846 times


In the third photo I drew in a location where it seems to me the fuse needs reinforcement as with a carbon rod.

Mike
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Re: AXN battery mount

Postby cynr100 » Sun Aug 05, 2012 8:48 pm

Mike,
You will find it difficult to bend the carbon rods and keep them in place, best to apply them as they are and retain using fibre tape. Bruce has suggested carbon fibre plates fixed across the tail break, rejoin the tail by gluing then shave a flat surface on both vertical sides to accommodate the carbon plate, afix by glue.
The nose has been weakened and will need more than glue to retain original strength so I would suggest:
1/Strip out all electrics and bath nose in hot water until all the wrinkles are removed.
2/Using the kit glue close the gap in the nose and apply thin strips (10mm) of reinforced tape 90deg to the joint.

Hot water, you will notice that the surface of the foam will take on a pimply appearance, this can be smoothed out by rolling with a biro or AA battery.
The tape, will strengthen the damaged nose and hold it together for the next bunt. Overlap the tape in a crossways position under the fuselage, this will seat the tape flat.

All in all, not too much damage there, have a look at Xjets YouTube channel and look for the ugliest AXN, it belongs to Doc :lol: :lol: and it was still flying.

Dennis
Not enough time in the day for all my crazy ideas, I'm not slow, I'm just pacing myself
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Re: AXN battery mount

Postby mikem » Sun Aug 05, 2012 9:48 pm

Dennis,

I like the idea of coaxing the nose into shape with hot water... will do that.

I was thinking of cutting a trench so the carbon rods would bury-in completely straight. Not sure what that would feel like until I get some CF rods on hand in a few days. That's my plan A. Perhaps CF tape is a better plan though, I don't have any of that... what to use for glue? I ordered from HK a 100ml bottle of the standard Chinese EPO glue that comes with the AXNs, I suppose that will work as well on CF.

Another thing I haven't tried but which looks interesting is "Sugru". Have you used it? Apparently it makes a rubbery outdoor-friendly patch on things, doesn't mind heat or cold. I don't know how heavy it is when it is applied so want to try it out on something first. I heard about it and just got a sample from a place in NYC where I often buy electronics gizmos:
http://adafruit.com/products/437
It may not like to stick to EPO foam... we'll see. Life is experimental isn't it?

"Biro" was a new word for me. Looking in my Aus-US, US-Aus dictionary I see it is what you blokes would pronounce "pin". I used to work with a physicist from Melbourne who was great fun to listen to... he had terrific stories and told them with gusto. He had married a lady from Hong Kong somewhere in the midst of getting *two* PhD's from Cambridge... Last I knew, years ago now, the two of them were planning to take a train from London, UK, to Australia. He had figured out how to thread through the bureaucrazy to ride the Trans-Siberian and then, since he was giving a paper in Beijing, he had permission to ride through China, then be on a boat-train I guess to Darwin or to wherever the rails begin on your patch. I never heard how the project came out but if he did it I imagine they have dined on that story a good many times since then! I got a jar of Kraft Vegemite from him one year for Christmas and that's the last I heard from them. I miss hearing him talk 'Strine'.

I have played too much this weekend so no AXN stuff for a couple of days. My wife is in Boise for a conference so me and the cat have to get some chores caught up before she arrives back tomorrow!

I hope Bruce hasn't jinxed the Mars landing with his Ladybird quad copter sendup! Will be up tonight watching the NASA channel, lands around 1:30am Eastern Daylight Time here. That's an amazing piece of RC isn't it?

cheers,
Mike
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Re: AXN battery mount

Postby cynr100 » Mon Aug 06, 2012 12:54 am

mikem wrote: I miss hearing him talk 'Strine'.


Strewth mate :!: :!: :lol: :lol: you're really getting into techy stuff to fix your AXN, if you can do it go for it. I prefer to keep my simple, reinforced tape (you guys call it duct tape :?: ) and hot glue. The more rigid you make it the more carnage is going to happen on each biffo, my carbon rods are only taped on. Like a cars' crash/crumble zone, designed to absorb impact without fatal damage.

Anyway, stop playing with your toys and get back to the house work :!: :lol: :lol: :mrgreen:

PS "Biro" ....ballpoint pen.........designed by Count Biro... 8-)
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Re: AXN battery mount

Postby mikem » Mon Aug 06, 2012 3:40 am

Duct tape, eh? "The handyman's secret weapon" as they say in Canada, according to Red Green... do you guys get that show? I'm sure I'll get less fussy as time goes on.

Right, "Biro".... a ballpoint "pin"... that's how Bruce would say it but he's a kiwi right?

I have been a fan of Captain Cook and have nifty book with charts of his three big voyages. I noticed that he was in Cairns, dropped anchor in Mission Bay on 9 June 1770. Is he a local hero there? That was just a couple of days before they ran aground up north and had to toss out all the cannons to float off. I can't imagine all the navigation they did with sextants and pitiful clocks for longitude, can you?

Well Callie and I are waiting for the Curiosity to land on Mars. It isn't easy to get cats interested in such things...
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