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Post by st on May 17, 2007 15:51:26 GMT 10
Andrew, you're message just made me realise that I could probably use this wing with a real short fuse also - effectively a plank. Alternatively, different wingspans on the same fuses. A mix-n-match solid wood plane family ;D
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Post by ezza on May 28, 2007 9:18:04 GMT 10
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Post by st on May 28, 2007 14:04:44 GMT 10
I spent last week relaxing on the beach at Tallebudgera ;D and don't get to work on it on the weekends, so not much has happened since the last update Nice video. It'l be just a little step up from the bee , I hope I can fly it
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Post by st on May 30, 2007 17:57:58 GMT 10
Had a little time to work on it yesterday. Got the horizontal stab and elevator done.
I used a silicone hinge, and I really like it. It's quicker and easier to do than using tape! It turned out to be a little stiffer than what I'd like, so I ran a blade down each side a little. Still slightly stiff so I then poked the blade through in a few locations and now it is great. Feels strong, and is aerodynamic.
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Post by thevon on May 30, 2007 22:01:21 GMT 10
I did silicon hinges for the first time when I did the ailerons on the Minij, and it's excellent - nothing better I reckon. Closes up the gap, very strong, easy to do. But you need to have a test run to get the feel of it. Good to use a syringe to squirt the bead of silicon, and cut/shape a tiny spatula from an ice cream container to spread it well. You only get one go at it really. But if it's wrong, you can wait a day and rip the whole thing off like a rubber band, and re-do it.
But I couldn't get it to work for foamies. Don't know why. I think it sticks best to a surface which is epoxied then sanded after curing, to roughen it up. If anyone works out how to use silicon for foamies I'd be keen.
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Post by st on Jan 3, 2008 13:44:37 GMT 10
Bringing up the dead ;D Just spent a bit of time in the shed and had a look at this unfinished project! Despite severe humidity changes over the last half year, the wing is still straight and flat! Must've selected a good piece of wood Stiff in torsion too, though a little flexible in bending over its length.... Wing mostly done, fuse largely done, tail only half done. Hmmm, if I turn it into a plank instead, then plane almost finished!! Less work to get it in the air, and means I don't need to buy a rudder servo (cheapo hey!)! SO, should I just turn it into a plank, or do the extra work and stuff and make it proper? ? For general flying and might try some DS'ing with it too.....
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Post by thevon on Jan 3, 2008 14:10:27 GMT 10
Simon, Sean would be good to comment on this. But my understanding is that certain airfoils are suited to planks - ie not interchangeable. I reckon that a conventional design with rudder and tailplane would be much more easy to set up and trim. Planks can be nearly impossible to get sorted out and it could be a nightmare with such a big heavy one. With a fuse and tail, it might fly badly at first but it will probably fly.
The Thorn is just the thing you need in the gale force winds lately!
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Post by st on Jan 3, 2008 14:31:31 GMT 10
......... The Thorn is just the thing you need in the gale force winds lately! You're right about that!!! Another crazy thought........ Planks are super sensitive in pitch (and hence require tight linkages, no servo slop etc). Wondering if a mini horizontal stabilizer, with no elevator, would remove some of this sensitivity?? Probably expect a small reduction in efficiency, but if it is kept small (1/3 or 1/4 normal size) might be OK?
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Post by sean on Jan 3, 2008 15:49:49 GMT 10
Hi Simon, glad to see this project is still going.
I'd keep it as a standard plane with a tail. Problem with planks is they land very fast and the timber has no shock absorbance. You can certainly build a standard plane without a rudder, it's definitely not needed, just smooths out turns if you're flying for maximum efficency.
Planks and conventionals do use different aerofoils but if you've eyeballed the aerofoil anyway it probably wouldn't matter much, although planks do seem more critical in this regard.
If you add a tail-plane then you need to have an elevator on the tail-plane for pitch control - adding a tail changes the aerodynamics so plank-style elevons wouldn't give reliable pitch control (they become flapperons and change the wing's camber, rather than provide pitch control). The only time you can have a fixed tail is when using wingerons - that's where the entire wings rotate for pitch and roll control.
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Post by st on Jan 7, 2008 10:42:20 GMT 10
Thanks fellas! I was thinking elevator when I wrote rudder earlier.......... Sticking with the conventional format - it will be easier to get flying I think. Bolts - wing to fuse join. What diameter plastic bolts do you guys use? I'm not going to be using plastic bolts because I refuse to pay the ripoff prices they want for them.... I have however come up with an alternative, that also keeps in theme with the rest of the plane Yep, pine bolts. ;D Hand screw a 1/4" fly nut onto 6mm dowel ($1-2/m) and you've cut (compressed really!) a thread that takes 20 seconds, can be used repeatably and works perfectly. Nut at each end and it is done. My only worry is that I think it may be a bit too strong! Might have to put a notch (couple strokes with the hacksaw) into it. Also working on elevator/aileron horns. It'd cost the factory in china a couple of cents to make the plastic ones that the shops charge a couple dollars for..........
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Post by thevon on Jan 7, 2008 11:42:45 GMT 10
Simon that things going to be so heavy you'll need very strong bolts! The plastic ones would shear every landing! Even Sean breaks them regularly on his Reaper and me on the Minij. The dowel could be just the thing. I have a stack of bits here so if you're going past you're welcome to drop in and grab some spare elevon horns ... (Woody Point).
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Post by st on Jan 7, 2008 12:02:26 GMT 10
Thanks Andrew, I'll try them with just a small notch and see how it goes. Probably better to er on the side of weakness at first (don't break anything major) - will find out soon enough! Your offer of elevon horns is very generous - but are you offering a supply for life? I'd like to come up with something cheap and repeatable! I guess I like being 'innovative' ! OK, I realise some of you would use other descriptive words ;D Going to silicon the ailerons on today. They are quite long so wish me luck!
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Post by thevon on Jan 7, 2008 13:32:59 GMT 10
Excellent. I've done silicon ailerons! Fiddly the first time but excellent method, works really well and never any hinge slop. Use plain masking tape, not the coloured stuff. Use a syringe to make a fine silicon bead. Cut a little spatula from an ice cream lid and shape it to spread the bead just the right way. Hold the aileron gap open wide while you spatula it. Don't make it too thick. Then lay the wing/aileron on the bench pressed flat with weights while it goes off. Don't be tempted to move it till it's hard. If you stuff it up you can rip it all out and try again.
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Post by sean on Jan 8, 2008 9:48:46 GMT 10
Hi Simon,
Regarding the bolts, they proved to be the weak point on my Reaper's wooden nose. I used 10/32 (approx 5mm) nylon bolts and thanks to the high landing speed, they'd shear on every other landing - I went through about 10 in a few weeks. I replaced them with metal bolts which worked for a while but a particularly heavy landing caused one of the bolts to tear it's hole. Finally I added double-sided tape between the wing and fuse, with the metal bolts and now all is good - the tape stops the wing shearing the bolts in a hit. If I were to build the Reaper again I'd goop the wing to the fuse and add a couple of bolts to be sure.
Sean.
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Post by thevon on Jan 8, 2008 10:47:20 GMT 10
Hot glue's not bad, as you can slide a hot knife back into the join to undo it. Not sure how it would go on such a heavy wing, though.
It would be great to have some sort of locating pins that can shear, combined with strong rubber bands holding the wing to the fuse so it can take a big hit without cracking something important.
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