Lumenier RB2205C-12 2400KV SKITZO Ceramic Bearing Motor
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Old Mar 30, 2005, 04:47 PM
fly1milehi is offline
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Why aren't there more 70+inch span flying wings?


Okay, Im not a slope genius when it comes to flying wings so I have to ask why there are not many 70+inch wings? Knowing what I do know about conventional designs (bigger span = better efficiency) It seems surprising to me that most of the flying wing designs on the slope are 60 inch wing spans or less.
Is it a convenience matter because many slopes require a bit of hiking? Or is it a more of a "higher degree of building skill required"? Give me your opinions!

Thanks in advance
Greg
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Old Mar 30, 2005, 04:54 PM
MtnGoat is offline
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Tu ne cede malis
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I've built 5 72" span wings with 2 still flying, and a 96" on the drawing board. Love 'em big. They fly better and you can see them way better too.

Problems that do get worse with size:

1) you *can* damage EPP if your plane weighs enough
2) must pay attention to good spars
3) servo size increases and must be anchored better than a foam pocket
4) surfaces get huge and must be carefully built to avoid flex and flutter
5) difficult to transport, must have a joiner system generally
6) wire and nylarod pushrods no longer suffice, I use solid CF rods with stainless ends attached with kevlar thread windings and soaked with CA
Old Mar 30, 2005, 05:06 PM
steve wenban is offline
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Crikey never leave beer behind
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big wing made of plastic


did you mean like this I built this awhile back flew very nicley but transporting it was a pain
SteveW
Old Mar 30, 2005, 05:16 PM
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Why not big wings? Because big wings roll like pigs... but they do loop really fast.
Old Mar 30, 2005, 07:05 PM
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Quote:
Originally Posted by steve wenban
did you mean like this I built this awhile back flew very nicley but transporting it was a pain
SteveW

OMG it looks like he has a 5 pound rock taped to it for ballast
Old Mar 30, 2005, 07:44 PM
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Because big wings take up an enormous amount of space in your vehicle.
Because they fly fast, but look slow (they look like any other combat wing at a distance).
Because while looking like a combat wing, they're really not useful for combat. And god help everyone if someone does take it down in the middle of the furball and it spirals into a crowd of people.
Because they have no flaps/flaperons/spoilerons they land fast, heavy, and hard on their face tearing up the covering and breaking elevons.
Because they're slower than comparable span planks and crunchies, which
generally don't suffer from all of the above problems.

ian
Old Mar 30, 2005, 08:14 PM
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Go to this link: http://www.aerodesign.de/ then click on Modell, then nuflugel and see some larger flying wings.

Here are a couple of great links for flying wing info: http://www.b2streamlines.com/winglinks.html or http://www.b2streamlines.com/OTW.html

Seems to me as you get larger, you have to deal with some structural issues like torsional strength etc. that foam and tape cannot handle.

Just think how cool this would look tooling around at your favorite slope (from the aerodesign.de link)
Last edited by sloperut; Mar 30, 2005 at 08:19 PM.
Old Mar 30, 2005, 09:15 PM
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Crikey never leave beer behind
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Quote:
Originally Posted by Dax
OMG it looks like he has a 5 pound rock taped to it for ballast
No dude thats the esky where I keep the beer cold
SteveW
Old Mar 30, 2005, 09:21 PM
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wow! that's awesome, may have to build myself one of those! ryan
Old Mar 30, 2005, 09:56 PM
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slope'n somewhere in the Andes
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MtnGoat summed it up very well: they require more commitment building, and if slammed into the ground for a landing, they'll break. With all those short-comings, you may as well just get a crunchie (heaven forbid... : )

Dieter Mahlein, ShredAir
Old Mar 30, 2005, 10:10 PM
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Interesting............... Most of you assumed that EPP is the only building material available or suitable and then the defination of performance seems to be only based on combat, and crash survival.

maybe new building techniques will enable bigger designs.... I know the Big Bluto looks incredible and if it goes out and sets a new record in DS we'll be rethinking... maybe.. LOL

Keep posting this is all good stuff!!!
Old Mar 30, 2005, 11:09 PM
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Tu ne cede malis
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bigger flies better. that's all you need to know! my 5 lb behemoth pretty much stays up with the weasels in light lift (low loading) , and when the wind machine turns on and the lead comes out, a couple of lbs on there and watch out!
Old Mar 31, 2005, 12:18 AM
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There's no inherent limit to the tailless market, only what "most people" are willing to pay for. Mainly that seems to be EPP and 48" or less, for many of the reasons raised by Ian and others, ergo most of the kits are designed to service that market.

Doesn't mean that this is ideal or anything, it's just what people want to buy. As for one-off/scratchbuilds, obviously there are all sorts of things out there, of which we only have a limited and imperfect grasp via RCGroups.

FWIW, here are couple "somethings" I'm working on...

"Aniso" 84", EPP


"FSW 01" 60" Balsa Sheeted Wing / Glass Fuse


Steve
Old Mar 31, 2005, 01:01 AM
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One of the biggest reasons is simply ..... Foam Size.

To get larger than 50" span, I need to join foam blanks together to make a larger wing: and that's a royal pain in the arse.

A friend and I are working on a couple of planes at the moment, (well... 3, but the 3rd one's different) The first one looks disturbingly like the Queen Bee (we cut the blanks 8 months ago, and have done nothing since), and the second one could be likened to the M60.... just, erm... more of an M"100" (with crow braking if i can balance it out right.... and a drag-chute if I can't )

Neither of them are EPP: they're going to be Vacuum Bagged, and the Plank will be finished in Carbon with a carbon/kevlar body.

It's True: big wings don't roll, But they're fun to buzz the slope with, and people will ALWAYS ask "how can it fly if it doesn't have a tailplane?"


At the moment though, time is being devoted to a not-so-crunchy "hard-plane"
Old Mar 31, 2005, 01:51 AM
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I built this last year but only have a couple of flights on it. It is kind of big and floaty, rolls realllly slooow. I was just going to build it with tape but peer pressure got me to veneer the wings, it does look nice. I am a bit scared of breaking it in half though as I undersized the wing rods quite badly. I think it is 2,18cm, it was the biggest I could get out of one sheet of roofmat.


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