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Acro Wot ARTF (balsa) chat


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  • 2 weeks later...

This is what happens to your stock ARTF Acro Wot if you don't replace the supplied metal U/C bolts with nylon alternatives...!

Purpose of my session this afternoon, having finally fitted the cowling and sorted static balancing (30g to tail, 20g to port wing tip) was to settle trims and rates for both normal flight and with landing-flaperons. Patch has been a bit of a mess recently, with a labyrinth of mole tunnels and hills, plus winter mud and the residue of sheep-shit from their Christmas visit.

Arrived to find mole-catcher had set first of his traps in southern half of N-S runway. There was still more than enough run into the gentle northerly for both takeoff and a careful landing, but I hadn't factored in the sudden dead-stick half way through the tank. Wasn't then ready - having safely cleared the trap marking-poles on my way in - for the excessive glide-speed without the slowing effect of a turning prop, and floated on fast beyond the north end of the runway. As she came down, at some distance from the flight-box, the undercarriage clipped a mole hill and ripped off in one clean snap, then she belly-landed in the soft grass.

The damage is easily repairable (including getting rid of the funny rebate behind the cowling which is unnecessary for IC), and I'll fit new captive-nut and NYLON bolts!dsc_0192 copy.jpg

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Edited By Jonathan M on 19/01/2017 23:09:12

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I'm sorry to see your bent AcroWot Jonathan, but I'm not sure that nylon bolts would have prevented much less damage than what's already been done judging by the size of those mole hills!

The possibility of deadstick issues is just one the reasons I've converted to electric power after using ic motors for well over 30 years of model flying.

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Posted by Bill_B on 20/01/2017 09:52:04:

I'm sorry to see your bent AcroWot Jonathan, but I'm not sure that nylon bolts would have prevented much less damage than what's already been done judging by the size of those mole hills!

Thanks for the commiserations Bill.

I'm working on the theory that a more robust solid ply mounting which bonded to the fuselage nose area with, say, 4mm nylon bolts should result in snapped bolts rather than reconstructive surgery to the airframe. A properly designed 'weakest-link' (with a few spare bolts) should do its job whatever causes excessive shock to the undercarriage... a carelessly-heavy landing or an unfortunate clip of Pen-y-fan.

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Sorry to  see that too Jonathan. I have the Kit Balsa not ARTF Acrowot with an OS80(the one in my header!). I have had it about 2 yrs and it is flown a lot. It's a bit heavier than the ARTF but flies very well. The reason I built the kit version is that I could strengthen it properly especially the undercarriage. It's much easier when you have full interior access while in construction. I have seen loads of the ARTFs rip undercarriage. Mine as no problem if I have to put it down in the adjacent ploughed field 😳. By the way I don't believe dead sticks are a good reason to choose electric, I have seen plenty of electric planes having to make forced landings too😊, but that's another discussion. I'm a committed IC fan especially for this model. ( I do enjoy foamies and electric helps occasionally). I like the Acrowot so much I'm considering another for a spare. I'm actually now half way through my Wot4 kit which will be a great winter hack and great fun with its air brakes. If I build another Acrowot I might put them on that too and increase aelieron depth to compensate 😊

Edited By Timothy Harris 1 on 20/01/2017 11:47:14

Edited By Timothy Harris 1 on 20/01/2017 11:47:39

Edited By Timothy Harris 1 on 20/01/2017 11:48:02

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Nice plane too Daniel. Rather than flex exhaust etc, I would just turn the exhaust round and point it down running out through bottom of cowl. That's what I m doing in my laser powered wot4 and already do in my laser powered Wots Wot XL. Connecting extra pipeoutside the plane might be a bit messy and cause drag.

Edited By Timothy Harris 1 on 20/01/2017 11:54:08

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Posted by Timothy Harris 1 on 20/01/2017 11:43:20:
..... By the way I don't believe dead sticks are a good reason to choose electric, I have seen plenty of electric planes having to make forced landings too😊, but that's another discussion. I'm a committed IC fan especially for this model.

Hi Timothy, I would have sent you a private message but your profile isn't public so I'll make a very brief interlude here: There are many other reasons for perhaps choosing electric power in the Acrowot (and other airframes), but eradicating dead sticks was one of my main reasons, not the sole reason. Also, I've been flying various electric powered aircraft for many years now and have yet to experience a deadstick landing. wink

Bill.

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dsc03973.jpgThis is how I modify the U/C to prevent the problem of ripping the bottom out of the acro wot, wot 4 and any other model with a similar arrangement. I use 6mm bolts and a plywood packer that is also about 6mm thick. The reason for this is so that when the bolts break and the heads come off there is enough thread to be able to get the remainder of the bolts out easily. Also use a small amount of cyno to fix the t nuts in otherwise they will work loose and you will have to remove the tank to get at them. nearly every one in our club has adopted this method as once the undercart are ripped out the tank bay is usually fuel soaked and never glues back with any strength.dsc03972.jpg

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Hi Glen, I posted my electric conversion setup a couple of pages ago, but I've reproduced here for you. Please note the original post mentioned an Eflite Power 60, this was a typo, it should have read 'Power 52'.

"For anyone that's thinking of going the electric route, you may find that the supplied battery tray isn't of much use for a 6s set up (5s is recommended in the manual), and that you will most likely need to manufacture your own tray as I did. Also, as I elected to use an Eflite Power 52 the supplied stand offs were too long so I fitted my own adjustable units to achieve the correct spinner clearance . The AUW of my particular Acrowot with a 6s 4000mAh battery is 2.98 Kg (6.5Lbs) and has unlimited vertical performance using a Graupner G-Sonic 13" x 8" prop and an aerobatic flight duration of 5-7 mins, dependant on throttle use."

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Thanks for that Glenn

I was going to fit 4 or 5mm nylon bolts, but I'll go with your setup and pop into my LMS tomorrow for 6mm with matching captive-nuts.

Clever idea the 6mm ply spacer. (My original plan for removing any broken studs was to heat up a parallel shank screwdriver and ram it into the stud fast enough to melt a slot!).

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  • 2 weeks later...

I did similar to Daniel to an artf Ripmax Wot4, light fibreglass epoxied to the ply floor and a couple of inches up the sides. Irretrievably damaged a succession of alloy and g/f undercarriages, but the fuze remained entirely undamaged.With hindsight if I'd used nylon bolts I wouldn't have even had to buy any replacement U/Cs either.

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  • 1 month later...

Massive discovery today...!

I couldn't understand why on previous flights my Acrowot needed 2-3mm of up-elevator trim for normal flight.

So, before going up to the field today, I measured the incidence of the wing relative to the tailplane (decalage if you like), and discovered that the wing actually had 1 degree of negative geometric incidence!

So I quickly made up a temporary shim, 100mm x 30mm x 4mm aero-ply, which fits under the trailing-edge and is held captive by two holes through which the nylon wing-bolts pass. This creates a positive incidence of about 0.5 degrees, which is how I understand fully-symmetric wings should be set up for traditional (i.e. non-3D) aeros.

Model now flies beautifully, with no elevator trim needed at all.

But this really begs the question as to why Ripmax supply an ARTF which is so dramatically out?!

Mind you, when my LMS originally got the Acrowot in for me, I discovered the tailplane was entirely lacking the elevator halves!

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Edited By Jonathan M on 11/03/2017 22:03:16

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