drcuzo
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Post by drcuzo on Jul 19, 2008 0:07:21 GMT 10
My JW kit arrived from Andrew this week. Securely packed as you can see. Out of the box, note the square tips. Tips and fuse shaped. I am missing the spars and ailerons. Does anyone have an opinion on the spars, fiberglass vs Carbon? Where can I buy aileron stock? Steve
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Post by sean on Jul 19, 2008 10:32:03 GMT 10
Hi Steve,
Looks great! For the spars go carbon, for DSing it's best to have the wings as stiff as possible. If possible get some carbon with thick side walls - the thin-walled stuff shatters really easily. In addition you could use Andrew's trick of glass spars top and bottom in addition to the main spar, but IMO carbon is best for the main spar.
It's hard to locate TE stock on the sunshine coast. Nambour Toyworld stock some but they don't have a huge range of sizes. What size do you need? I ordered some online once but that wasn't the best idea - one piece was very heavy balsa the other very light, and one was broken...
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drcuzo
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Post by drcuzo on Jul 19, 2008 10:52:07 GMT 10
Sean The ailerons are 36ml. I may need to try brisbane or Pete may have some. Steve
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Post by ezza on Jul 19, 2008 10:57:23 GMT 10
Nice pickup Steve. The standard JW kit comes with 6mm hollow carbon spars. That is what is in mine. The guys in the US usually replace these with solid 6mm carbon spars. They are a bit stiffer and easier to repair if you have a horrendous crash. Yes, ailerons are 36mm chord. Thickness from 6-7mm to 2mm. About 750mm long. Eric
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Post by thevon on Jul 19, 2008 11:43:04 GMT 10
Steve, I've bought aileron stock from Budget Hobbies Capalaba a couple of times ph 3823 3033. Great service, quick post delivery. However I'm not sure what sizes they stock. The ones I got were pretty thick, for the Bat.
But I also got some from Pete of Wowings recently - I think he did me a favour and I"m not sure if he wants to do it regularly, but worth asking. Pretty sure he has some 8mm x 40mm so if you trim a bit off the thick edge they'd probably be perfect.
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Post by jirvin4505 on Jul 19, 2008 11:54:15 GMT 10
Alternative TE stock..
I notice some of the Bunnings stores have balsa. Buy some stock of correct thickness and using a balsa plane (I have a David plane) shape the surface to correct taper. Takes less than 10 minutes.
You can get creative and use long lengths of different thickness music wire as thickness guages but as i am usually working to the closest cm (and in a hurry) I just use the plane and a quick sand.
Alternative2. More detailed - cut some TE stock from blue foam and vac bag it.
cheers jeff
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Post by sean on Jul 19, 2008 12:18:38 GMT 10
Regarding ways to make elevons - I've been playing around with hollow carbon elevons recently. As far as strength goes they're quite incredible and it takes no special tools or skills. The technique involves laying up flat carbon sheet on a piece of waxed glass, cutting a top and bottom for each elevon from the cured carbon sheet, then CA gluing a balsa LE inbetwen to the top and bottom sheets. It's dead-simple but a little fiddly. I'm no expert when it comes to composite construction so I reckon anyone could do it. I'm gonna make some for my Moth so I'll post a quick thread on it.
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Post by skyboyken on Jul 19, 2008 22:12:07 GMT 10
You can get a selection of carbon rod and tube sizes from: www.briskites.com.auI just picked up 6mm and 12mm. As a suggestion, have a look at the thickness of the JW wing nearest the tip where the spar goes in, and try to get the largest carbon tube or rod you can to fit. Hobbyrama has a good selection of balsa elevon stock. You can glass it (that's what I do) or cover it with New Stuff (I do that too). You're after stiff and light. Stiff and heavy is no good because weight aft takes a BUNCH of lead up front to balance out. Go Great, I look forward to seeing your JW fly. Ken.
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drcuzo
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Post by drcuzo on Jul 20, 2008 21:35:09 GMT 10
Thanks Ken I had checked out their site and could not find the rods but went back and found them today. I will order this week. Can anyone tell me what to do with the TE of the wing. I see builds were people put a wood or CF spar along the TE and the aileron attaches to it. What is the purpose of this. The building instructions from Bowman's Hobbies do not include a TE spar. I am also interested in opinions on aileron hinges. The servo's I am looking at are Hitec 5955TG (US$ 85.99) do you think this is overkill for this model? I figure if you buy quality they will last and you can use them in other projects later. www.servocity.com/~servo/html/hs-5955tg.htmlThanks Steve
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Post by sean on Jul 20, 2008 22:12:05 GMT 10
I find it much easier to get a good hinge joint with a wood or carbon dragspar on the TE. It also helps stop the covering from deforming the wing near the TE, and adds a bit of much-needed stiffness, though probably not by a great deal.
The 5955TGs sound a bit like overkill to me, but if you don't mind spending the money you won't regret it, and as you say they should outlast the airframe. A cheaper option would be the standard size, karbonite digi Hitecs. They're about $40 I think? Andrew used them in his Bat and they're brilliant in a plane of this type. The standard size servos have bigger gears so you'd be very hard pressed stripping the karbonite gears - even standard size nylon gears are incredibly tough and hard to strip.
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Post by Hamburglar on Jul 21, 2008 8:55:02 GMT 10
Have a look at the Hyperion Atlas digitals. I'm using the DS-13 TMB in my Moth and they are great. I think I paid US$34ea (shipped) from Windrider.
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Post by Pij on Jul 21, 2008 13:28:32 GMT 10
My way of looking at drag-spars is this:
Grab a strip-hinge of some type, maybe a piano hinge or even a bit of cardboard which you have creased down the middle. Bend it to see the hinge work. THEN put a curve into it, along the hinge, and try to bend the hinge. A curve hinge line can't hinge! If you try to, it will tear away at one end, or both ends, or the middle.
Under load, a wing will bend. But a curved elevon hinge will either not work, or will try to tear away somewhere.
The drag spar keeps your hinge-line straight.
(OK, shoot me down now - I have never flown anything with a drag spar. My Orbus is still in the box, waiting on a new wing pair to be sent. I didn't know what drag-spars were for until Andrew (I think) explained it to me.)
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drcuzo
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Post by drcuzo on Jul 21, 2008 14:15:05 GMT 10
Thanks Pij & Jordan
Pij - a scholarly explanation - I'm convinced. I think I will goop some CF stip along the edge.
Jordan - thanks for that. I will order those servo's tonight - great value.
Steve
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Post by thevon on Jul 21, 2008 18:40:43 GMT 10
If you can fit std size servos in and can afford the $45 or so for them, get the HS5475's. No word of a lie, they're unreal. The digital resolution is great (very fine), huge power, and NO slop. I recently took mine out of the old Bat, which had heaps of use and many enormous prangs. Since it was my main learner DSer, it was totally smacked in many times. But they STILL have ZERO slop and are like new.
I think the carbon strips aren't enough for a dragspar as they'll kink and crack easily. If you're using carbon, get the 1.2mm thick (I think) stuff from Hobby model warehouse, or use wood.
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drcuzo
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Post by drcuzo on Jul 21, 2008 20:49:22 GMT 10
Andrew
What type of wood do you use?
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