rcspaceflight
creator of virtual planes
And here I am thinking about using a NiMH pack for my DLG. I also plan on using steel on mine. ... It's probably going to turn out a hair heavy.
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I didn't add details about the tail feathers yet because the design is still a bit in the air. I know though that the original design I had for the hstab wasn't going to work. It used to have a little riser piece so the elevator could travel down like a traditional DLG but this was a very weak point in the foam board design. Removing that was necessary.
As of now I have the hstab sitting at the end of the boom and the vstab is either going to notch into the arrow in front of the hstab or ????? Not sure yet.
I'm still planning on using a rudder so I'm going to continue working out a solution to the riser issue. But just a thought.
But if you're not using a rudder, I don't really see a reason why you can't just have them switch places, with the elevator hanging past the end of the tail boom instead. Then you wouldn't need a riser at all, and could just glue the vstab to the side of the tail boom in front of the hstab.
Guys, I love what you're doing here, but your material restrictions are not making this easier.
A cheap FB glider has already been built, using parts that aren't hard to find (yes, they need to be ordered or picked up at a good LHS, but most good LHS's will have it) and it flies pretty well for a 30' wing and seemed to hold up.
The typical term used around the DLG community is a "Tail Pylon", and building a simple one that is more durable than the plane is amazingly easy . . . if you use the right parts.
The main core is a small piece of balsa somewhere between 3/8-1/2" square, and about as long as the unmoving part of the H-Stab, grain counter to the long dimension(the grain will need to be vertical when you're done). Add on a dab of Rubbing-alcohol thinned epoxy (yes, epoxy) and a small piece of 12k or 24k carbon tow and you can build it super light -- my 0.1g scale couldn't even register it. I built one a couple of nights ago, and took about an hour's worth of sanding and shaping, another 10 minutes of doing a layup on a piece of shoe-polished packing tape.
Seriously, that's not hard. At all. The only downside is you have to wait for the epoxy to cure, and a simple layup on a piece of packing tape is something ANYBODY can do. I wouldn't hesitate to let a kid do these (with parental supervision, but melted hot glue is more hazardous than any of this stuff)
If you hate unfinished carbon that much and don't mind a 0.1 gram or two (you really should, but . . . ) wrap the balsa cross grain with spiderwire then lightly soak with thinned epoxy.
Guys, I love what you're doing here, but your material restrictions are not making this easier.
A cheap FB glider has already been built, using parts that aren't hard to find (yes, they need to be ordered or picked up at a good LHS, but most good LHS's will have it) and it flies pretty well for a 30' wing and seemed to hold up. The guy who built it didn't get stuck on material restrictions -- carbon strip spar (lighter smaller and makes for a single sheet thick wing), Balsa tail surfaces, and 1/16" ply for a dihedral brace. He sanded the wing instead of beveling and folding it. He then cleaned the wing and covered with packing tape.
By all means, guys, keep building, but I find it frustrating watching y'all struggle to not take the simple solutions others have been using for years out of fear a novice will have learn something new or have to wait for an $5 EBAY order to arrive.
Yeah, I wouldn't recommend they bag a new wing, or hotwire cores (neither of which is hard, but the setup is pretty involved), but this kind of work can be done in an evening for next to nothing with almost no experience except how to operate a piece of sandpaper, polish a shoe and stir a mixing stick, it's easier than the hoops you're already jumping through . . . and makes a huge difference in how the final airframe performs.
... rudder ... you really want the vstab to be furthest from the wings.
...
Other than those two things I can't really think of a reason to not switch them.
Thanks for the correction on the pylon, that makes more sense than riser
The process you described just to make this pylon though is more involved than making my entire DLG.
I had more to say about the rest of your reply, but I don't want to dilute that point. You've professed you want to be in that top corner -- fixed wing, advanced build -- right? You're limiting the "everyman" in your mind to what they can already do now, instead of what they CAN do when the expert (it's your build, so that would be you) shows them the simple trick to doing the next step better. So what if it takes a bit more work?
No need to think further, those are THE two reasons not to switch them...on a competition ship. In DLG competition, control input is your enemy because surface deflection = drag = lost energy = shorter time aloft. Most pros will do as little as possible with the ailerons, turning mostly with tiny rudder inputs.
But those are not really concerns of this aircraft. Not that you don't want the best performance out of your design, but you're still going to get a great DLG flying experience with just aileron/elevator ....which is basically how I flew my carbon DLG anyway since that's what I know, and I had a blast!
To that point, I don't see (much) reason for even having dihedral. If you've got full span flaperons and elevator control, you could simplify the wing to have a single solid full span spar - eliminating the aluminum weight as well. Just a thought.
That being said, if you DO want rudder, and to mount your horizontal on a pylon, a double-layer glued FB post served me well. It definitely was not the weak point of my design.
Of course it's easy to build a cheap, durable DLG if it only has a 30" wingspan. But where is the fun in a little guy?
Right now I'm debating what wingspan to go with for my next attempt. I think Nic is right with going with a 50" wingspan. Nice and big for a more floaty result. It's pushing the limits with G forces. But it's not pushing those limits too far. Maybe 60" would be better, but maybe that's starting to get awkward to swing around.
(Sorry if wingspan size was already covered in this thread, I didn't read 100% of it.)
The only restrictions I'm giving myself is price and availability of materials. I'm thinking of using a plastic bottle for the nose. But I haven't gotten that far in the design yet. I do know I'm going to try bamboo for the wingspar and fuselage rod. Bamboo has about the same tensile strength as aluminum. Which is about half of steel. Which is no where near how strong carbon fiber is though. But bamboo skewers Gorilla Glued together and wrapped in electrical tape should work. I guess I'll find out.
I didn't mean to talk down to the smaller DLG. You won't be able to launch it as high or (in theory) get the level of performance compared to a larger one though. I just think solving the structural issues at that size are not really an issue or challenge. Going for the 50" size is to attempt a high level of performance and with that comes the additional design challenges (my favorite part).
Are you planning to run bbq down the whole wing? Like normal 12" skewers or the beefy yard long spears?
Thanks for confirming that! You make a good point too, without rudder you can ditch the dihedral.. hmm. Can you get carbon that long for a decent price?
I disagree . . . and that's my point. This method takes a little LONGER but it's no harder or less approachable.
So what if it adds an evening to something that used to take 5 minutes but doesn't work? No this isn't fast, but it is functional and easy enough anyone can do it.
Doing a simple cut-shape-epoxy (with or without the carbon tow) of the pylon can solve your problem of a sound pylon in a short evening's worth of work. Epoxy, is certainly in every hobbyist household and if not, a quick trip to lowes can fix that. Balsa? Why shouldn't a hobbyist have some on hand? Pick up some 1/2" square sticks from Michaels or Hobby Lobby the cut and glue them together into a larger strip with Elmers glue. It's a good material to have on hand. As for carbon, you can do it without, but it will be heavier, you just need the spectra fishing line to do it. I can pick up each of those items within 10 minutes of me at places that don't carry Horizon RTFs. The carbon is a week away via EBAY (and yeah, I have a lot of it in my shop, and you may be surprised how many hobbyist have it in theirs.
I was replying to CraftyDan sharing a link to a 30" DLG. That's easy to do cheap.