QUAD WING CONCEPT GLIDER

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Been toying with an idea for a quad wing glider for quite a while so I thought I’d give it a try. I like oddroc gliders that don’t look like they ought to fly—but do. Just a sport flyer for kicks and giggles. Though I’ve seen some bi-plane designs (one wing stacked on top of another) I’ve yet to see a model with 4 wings in a linear configuration. There’s every reason to believe it may not work…and for so many reasons, like airflow disruption between the wings (e.g. downwash), instability of back-to-back airfoils, locating the CG in the wrong place…well you get the idea.

This may end up being a short build thread but I just couldn't resist following through to see if it’s a workable concept or just wishful thinking. Doesn’t hurt to try right?

Below is the rough sketch of what I’m thinking about. To minimize major downwash problems from the forward wing I’ll mount it on the bottom of the fuse, and mount the aft wing on the top. Also thinking of making it a Y-tail, or possibly a V-tail to lessen weight. Unlike my other scratch built explorations, this one will be a boost glider, both to reduce weight further and to simplify things (since there’s already enough parts that have to work together to make it glide-stable).

Considering it’ll have two sets of wings, I’ll be using 1/16” balsa for all the flying surfaces to keep weight down. Given that, I may tissue the wings so they won’t shred even though I’m only going to be using 13mm motors. Probably won’t bother airfoiling the wings at this stage.


dragonfly sketch.jpg
 
Somewhere in the cobwebs of my brain, I thought I had seen a delta-ish wing model, with 3 wings.

First wing was 1/3 length of last wing.

Second wing was 2/3 length of last wing.

But I can't find it. Best of luck.
 
Here are some thoughts:

https://www.youtube.com/watch?v=U-63LycJyts

Look at the first model, and at the 3 minute mark.

First model was stacked winged, almost like the old WWI biplanes. I was envisioning something with a linear arrangement, like a dragonfly. (Hmmm...might make a good name for this model). The flyer at the 3 minute mark was closer to what I was thinking except with only 2 wings and not flapping lol. Wish I could make mine do that but the mechanics of it are beyond me.
 
You are looking at making a rocket glider, so I think you are in the right spot. Responses sometimes take a little while.
 
IMG_0718.jpg


Put together a prototype tester from scrap balsa and thin cardboard. Made the stab a bit oversize to compensate for the larger area of 4 wings. I had to guesstimate the location for the wings based on where a single wing would be located in relation to the tail. Using the trailing edge of the aft wing I measured 2.5X forward of the tail LE.

The CG should probably fall somewhere slightly back of the aft wing’s LE. I admit I’m in unfamiliar territory here. But what the heck, all it cost me is a little bit of time to see if I can get something workable. Things are just attached with glue gun adhesive so if I have to move things around, no big deal.

Tried a few hand tosses and ended up having to move the wings forward a smidge plus add some nose weight. But hey, I’m pretty stoked that it actually does glide pretty good, though I can’t toss it more than 10 feet without it running into a lamp, couch, wall etc. I’ll test fly it outside as soon as the weather permits. If it actually glides a decent distance I’ll move on to a balsa build. Things look encouraging!
 
Cold and windy but I was able to duck outside real quick for a test flight.
One thing I can say is that it likes still air much better than bucking a breeze. The 10-12mph gusts kept blowing it off course when tossing it upwind
while downwind tosses tend to make it fishtail some. Not surprising since it weighs little more than a paper airplane and doesn’t have the mass to
push through easily. Things look promising enough to move on to a balsa version though.

All you knowledgeable glider peeps out there please feel free to chime in with your suggestions/advice/experience.
I’m pretty much flying blind here.:confused2:

[video=youtube;AC9gly_PLCk]https://www.youtube.com/watch?v=AC9gly_PLCk&feature=youtu.be[/video]
 
IMG_0715.jpg

Only now realized the unintended “flying blind” pun. :eyeroll:

Decided to laminate two 1/16” balsa strips for the fuselage. It’s something I’ve seen the chuck glider guys do to get a lightweight fuse that’s still stronger than a solid piece of 1/8” balsa. I’ll also add a 1/16” x 1/8” strip to the bottom of the fuse to stiffen and reinforce it as extra insurance.

Since I’ve snapped a few other gliders during trimming, I’m considering ordering denser hard balsa to use for fuselage sticks instead of just using whatever I can find at the hobby stores (I’ve given up on spruce. No one here carries it and it’s not all that plentiful or inexpensive online either). Or I may opt to try carbon fiber tubes. At least they’re easier to get locally.

This should be a fairly fast build since I’m not bothering with sanding in airfoils, just rounding the leading/trailing edges of the wings/stab/tail.

The only mod I’m making to the fuse boom is sanding in a 2° incidence for the tail so it kicks the nose up once the motor pod releases the glider.
 
This old Whitewings set had a 5 winged glider that worked fine. I don't see any issue with you are building.

kj

ww.jpg
 
Hmm......what if the Front Wing was angled down (at the edges; negative dihedral)? Or maybe the back wing angled down.

I am suggesting this for mainly looks, because it would cause the glider to look a little more like a dragonfly (maybe).

Hey, and the Front Wing with opposite dihedral might allow for TWIN SWING WINGS!!! :cool::cool::cool: Sexy........
 
This old Whitewings set had a 5 winged glider that worked fine. I don't see any issue with you are building.

kj

FIVE wings? How cool! White wings are books about paper planes? Hmmm...might be a good source of ideas for odd roc gliders. Also encouraging that my build might actually get off the ground (no pun intended). I should know soon, no flaps, hinges, slide wing mechanisms, etc. to worry about with this build.
 
Setting the wings free.

All flight surfaces shaped except for the rudder, which I may or may not use. I’ll tissue everything except the fuse boom. It’s lightweight and cheap insurance against shredding and I’ve never had a failure yet.

IMG_0712.jpg
 
Hmm......what if the Front Wing was angled down (at the edges; negative dihedral)? Or maybe the back wing angled down.

I am suggesting this for mainly looks, because it would cause the glider to look a little more like a dragonfly (maybe).

Hey, and the Front Wing with opposite dihedral might allow for TWIN SWING WINGS!!! :cool::cool::cool: Sexy........


Interesting ideas, especially the swing wings but maybe for version 2.
It's probably safer to keep it simple for now to increase the chances that this design will actually work--less sexy but less to go wrong.
 
All ready for 2 coats of dope, sanding, and then tissuing. Might have to finish tissuing tomorrow depending on how fast the dope cures, but otherwise things are
moving along pretty fast.

IMG_0723.jpg


IMG_0727.jpg
 
Laid the tissue down with the grain running the long way, brushed the tissue with lacquer thinner and it’s stuck down tight after 60 seconds. Still needs a spritz of water to shrink out the fine wrinkles after I trim off all the excess.

IMG_0731.jpg
 
Not surprisingly one wing is a tad heavier than the other. That one will go up front.

IMG_0737.jpg


Really like this technique I learned from the chuck glider builders: cut the wing out as a single piece than carefully slice them part way through on the mid-line. Sand in a bevel then raise one wing to the total dihedral angle. Way easier than sanding the root edges of each wing separately to get the same dihedral.

IMG_0743.jpg


Kind of a pain getting the forward wing glued on perfectly horizontal with the fuselage boom, so my fin alignment jig really came in handy to prop things up till the glue dried. The aft wing should be a tad easier…just need to sand the bottom where the wings meet to make it flat enough to balance on the top of the fuse.

IMG_0746.jpg
 
Minor disaster: the fuselage broke right between the wings after it sailed off the lawn and hit the driveway.
I’m surprised it snapped at all considering I added a reinforcing balsa strip to the bottom of the fuse boom. I’ll salvage whatever I can and make another fuselage. I just need to figure out how to make it stronger. I’m thinking of reinforcing the sides of the boom from the nose back to aft wing with some 1/64” ply that I have. Or tissue-wrapping the length of the boom?


IMG_0751.jpg
 
Back in business. Fortunately I was able to salvage the wings, tail and rudder. A little careful use of alcohol
to soften the wood glue and acetone to dissolve the CA and I was able to strip them off intact.
Added a 1/64” ply strip to reinforce the front half of the fuselage boom. Looks good as new.

IMG_0820.jpg


Just need to put together a pop pod to get it airborne. I decided to go with something longer
just to make sure it’s launch-stable. 12” ought to do it.

IMG_0798.jpg


I may do an Easter launch tomorrow if I can finish trimming it today. Current weight is 12g (0.4oz).
I’ll add some color for visibility after. I’m eager to see how it performs. Fingers crossed.
 
Happy Easter everyone! Did an early morning test flight. Pleasantly surprised. (Well okay I’m actually kinda stunned and stupid happy) that:
(1) it didn’t loop into the ground at launch;
(2) it boosted straight with only a single 360° rotation on the way up (maybe that’s why #1 didn’t happen);
(3) it didn’t lawn dart—it only almost did because the A3-4T delay is waaaay too long;
(4) it transitioned to a nice shallow glide immediately after the ejection charge—though it must have been only 15 or 20 feet up by that point. And the 10pmh gusts didn’t knock it out of control.

I actually expected the worst because it seems to violate a lot of aerodynamic principles (or I’m just not familiar enough with them). I’m still not completely sure why it works as well as it does…or at all. Guess it doesn’t matter, I’m just glad it does. Guess it’s earned its paint. :D
 
Congrats!! :headbang::cheers::wave:

I think you were also very careful with your build. :clap: Well done.
 
A light fog of fluorescent orange and some permanent marker work and the Dragonfly is all dressed for her debut at my club’s launch this month. Hopefully someone will bring a video cam and will agree to get some footage (I suck at grabbing video, especially when I have to keep one eye on the glider and the other on the motor pod. That’s about as possible as licking your forehead with your tongue. Unless you’re Gene Simmons maybe).

IMG_0979.jpg

Some thoughts: I need to go with an A10-3T. The higher impulse and one second shorter delay will really keep it from deploying so close to the ground. Hopefully it won’t shred with the A10.
I’m also thinking about doing an upscale with slightly larger wings, maybe 15% bigger since the current ones are a bit stubby and the glider could use more lift. I think I’ll also go with 4mm square hollow carbon rods for the fuselage this time. I’ll be back to update the thread as soon as I free up some time to get working on version 2.0.

IMG_0977.jpg
 
Very cool Eric.

Funny, I have been working on a “quad wing” concept for a few years, but my concept was a biplane, one wing pretty much just above the other. Had never thought of a “staggered” configuration.

My limited reading on biplane gliders is that, for GLIDERS the biplane config has more drag for same surface area of the wing compared to monoplane, bit that my be offset by advantages to shorter wings during boost on a rocket model.

I think the perfect support for your fuselage would be a carbon fiber STRIP. Would have more surface are to attach than a rod, still pretty light, and would not need to run the full length. Because it is flat would add minimal drag as it conforms to your fuselage.

I am trying to mate up a biplane with a square cross section fuselage. I am thinking while a square cross section definitely has more drag than a cylinder, for gliders and external blade helicopter (rotaroc and my designs, not the competition ones which carry the blades internally) the biggest drag is the multiple interfaces (for helis and for folded or swing wing gliders— those that alter wing orientation at deployment ) between the wings or blades and the rocket body causes a ton of drag.

You have probably seen the Jenny, a biplane fixed model .

https://www.rocketreviews.com/plans---estes-industries-flying-jenny-mike-salter.html

https://www.spacemodeling.org/jimz/eirp/eirp_21b.tif

Here is a link to my failed attempt of a biplane swing wing

https://www.rocketryforum.com/showt...e-Swing-Wing-Boost-Glider&highlight=Agamemnon

I continue to enjoy your builds!

Tom
 
Very cool Eric.

Funny, I have been working on a “quad wing” concept for a few years, but my concept was a biplane, one wing pretty much just above the other. Had never thought of a “staggered” configuration.

My limited reading on biplane gliders is that, for GLIDERS the biplane config has more drag for same surface area of the wing compared to monoplane, bit that my be offset by advantages to shorter wings during boost on a rocket model.

I think the perfect support for your fuselage would be a carbon fiber STRIP. Would have more surface are to attach than a rod, still pretty light, and would not need to run the full length. Because it is flat would add minimal drag as it conforms to your fuselage.

I am trying to mate up a biplane with a square cross section fuselage. I am thinking while a square cross section definitely has more drag than a cylinder, for gliders and external blade helicopter (rotaroc and my designs, not the competition ones which carry the blades internally) the biggest drag is the multiple interfaces (for helis and for folded or swing wing gliders— those that alter wing orientation at deployment ) between the wings or blades and the rocket body causes a ton of drag.

You have probably seen the Jenny, a biplane fixed model .

https://www.rocketreviews.com/plans---estes-industries-flying-jenny-mike-salter.html

https://www.spacemodeling.org/jimz/eirp/eirp_21b.tif

Here is a link to my failed attempt of a biplane swing wing

https://www.rocketryforum.com/showt...e-Swing-Wing-Boost-Glider&highlight=Agamemnon

I continue to enjoy your builds!

Tom


You have some mad engineering skills! That biplane design is impressive in terms of how you solved some pretty complex functions. I really like how you used (basically) a single strand of elastic to perform multiple things like hold the engine and flaps in place as well as anchor the wings in launch position.
 
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