Marxpek

[TC15] Paper Plane, a Functioning Glider

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This is something i was already eager to try before this competition, but never actually ordered the sails.. but tonight a bricklink package arrived with the 42074 race yacht sails.

Here is the idea: make a functioning glider looking somewhat like a paper plane.

This is what i did for now:

Model A:

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Model B:

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Both models can actually glide (short indoor couch tests..) when you throw them with a little bit of force,

I tend to expand the A model since it has a the bigger wings compared to the weight of the subframe, but i do like the simplicity of the single wing plane.

The long axles with the connectors allow to slide the center of gravity back and forth, something i will play with a bit later to balance them out for longer flights, the frame will most likely become fully black for least visibility.

Please let me know what you think and what model you like best!

 

 

 

 

 

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A nice, original take on the competition theme! :thumbup: Also, good to see someone use these parts for something useful.

I prefer the "model A" with 2 pairs of wings, since it's less "trivial" and therefore feels more like an actual model rather than just a little test thingy.

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Nice! I like the first one best, I think it looks a bit sleeker than the second one.

2 hours ago, TechnicRCRacer said:

Lego can fly now!

Well, gliding is more like slow falling than flying, but I think it's best not to start that discussion again... :wink:

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Great idea - it would be very interesting to see how well this can work.

I say go with whatever design flies best, and fine tune it! 

Could a powered launcher be possible...?

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Cool :thumbup::thumbup::thumbup: I was hoping someone would try this. When the set with sails came out I thought this might actually work for a small glider, but never went to buy additional sails. I hope you succeed. The idea with launcher is also great and would add some more Technic to the build. 

Best regards!

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Very interesting, I will definitely be keeping an eye on this thread to see how it works out. May very well have to pick up a second sailboat and have a go at this myself, not for the contest of course. 

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This is super cool! :thumbup: Now I want to get those sails :D I'm also curious how this works out.

How about replacing some axles with hoses (the thin, rigid ones)? Might save some weight. 

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That's an excellent concept, it's cool to know it actually flies! I agree that the first one looks a bit sleeker. Once you've got a final design I'd love to see a video of it in flight.

11 hours ago, mocbuild101 said:

Well, gliding is more like slow falling than flying, but I think it's best not to start that discussion again... :wink:

It's falling with style :laugh:

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Thanks for the feedback everyone! 

I will continue with model A, it looks and performs better, so it is an easy pick in the end.

Observant forum readers might have seen my request to use my DIY pneumatic container, which got denied, so i have been thinking about launching this.. but considering my DIY air container was a modded fire-extinguisher, it is probably a good thing it got denied, it would have blown this thing into pieces and destroy the sails.

I also considered a winch system, a pulley system and a system using the thin tracks, but after throwing the plane i am getting doubts whether a launcher would be effective, you need quite a delicate throw to make it glide and at the moment the plane itself gets priority, the balance on the plane is a bit tricky, one big other issue is the fact the sails want to curl up a bit, giving a nice wing shape on one side, but the other side does not want to sit really well as it is arched opposing to how it wants to curl up.

If anyone has some advice on how to curl these sails the other way, i would love to hear, i was considering rolling them up and leave them for a few days in that position, but i have no idea if it will do anything at all.

I've made some small changes, the front 10L "bumper axles" are now separated so they allow the sails in between, before there was a little stress on the sails because they could not go in between:

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There is also a bit of additional weight in the front because the rear got a bit heavier, it was needed for balance, i will reduce the weight more, that will also require a re-balancing, so until the design is final i will not spend too much time on balancing. The rear now has a few connectors making it possible to make small adjustments to the wing's positions, before there was a unsupported bar holding the wings down. The old setup performed fine, but was no part of the frame and held together by the connection holed in the sails, something i do not really like, i do not want to tear them and impacting the ground after being thrown is always a risk on damage i think. If the added weight turn out to be a big issue i might still use the old system, but for now i like the way i can fine tune the wings positions.

more later..

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1 hour ago, Marxpek said:

If anyone has some advice on how to curl these sails the other way...

Have you tried to do something with strings? Also maybe try to move those back sails holders (seen on picture 2) underneath the sails. Maybe that way you can somewhat constrict the curling, and it will give you a clean top surface.

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have you considered adding a vertical tailplane ? that may add some stability if you think of a paper plane even if it doesn't have a tailplane sticking above the wings it has a vertical surface for the fuselage

 

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16 hours ago, Marxpek said:

i was considering rolling them up and leave them for a few days in that position, but i have no idea if it will do anything at all.

I think, this should work

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5 hours ago, Seasider said:

have you considered adding a vertical tailplane ?

I have tried to fit another sail in between, but it just looks off, way too big, and it is sort of hanging without support, only the biggest sail can be used if you want to support the top and it would need more weight in the rear, but all seems fixed when i tried this:

20 hours ago, pagicence said:

Also maybe try to move those back sails holders (seen on picture 2) underneath the sails. Maybe that way you can somewhat constrict the curling, and it will give you a clean top surface.

This my dear friend, was a stroke of genius! Simple and highly effective, thanks for that! Like Seasider mentioned the vertical plane could be better for a more stable flight, but your idea solved this as well, i was able to to throw it a good 5-6 meters into my couch (that's about how far i can get from it now, damn you Christmas tree!) for a few times, despite the still not perfectly shaped wing , on top of that: a little weight reduction as well!

Here is how the rear looks now:

800x450.jpg

Next step is to curl back one of the sets of wings, I will roll them up tonight and leave them like that until the weekend, fingers crossed.

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Really happy of seeing it done, and it flies!

 

I thought on doing using the friend's one , because of the uncutted tip, but never ordered the parts to make a try.

There are smaller "windsurf" sails in two sizes for that vertical tail, if you really want to, check "plastic triangle" in bricklink

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This weekend i have done some outdoor test throws, and man.. that is another story from throwing it into a couch, conditions were far from ideal, but not really windy either. results where not that great, more tweaking to do, but while doing this i saw an easy way to improve the design:

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the nose has an adjustable weight system built in (2L crossbeams) it can also resist some impact, it just slides back.

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The rear has some weight reduced but as you can see the frame is not 100% straight, seems one of the axles is torqued, I'll have to fix this or use another one.

The old 4L wide structure is now 2L wide, it looks better but also lets less air pass through the center of the plane. I am also working a way to attach the sails without the ball-joints in between the 2 connectors using half-pins and the 4L "Lightsabre blade" bar , fully closing the gap, like a real paper plane has and catching more air. But since the sails will go in between the 2 connectors it will not be a 100% true Lego connection, what do you all think about that? Allow it? the sails are really paper thin and i am inclined to try it after this was tested.

In the meanwhile i am seriously looking into adding weight to the front, it tends to glide for 5-6 meters when i throw it carefully, then stalls and heads for the ground in a hurry, in other words, it is going too slow for its wings to carry it, but when I throw this harder it does not go anywhere since the COG is still too far back and the heavier rear overtakes the front resulting in a instant crash, of course. To be able to throw it harder there are 2 solutions, remove weight from the rear, or add some to the front. Weight reduction in the rear would be great, but very hard to do so, @Davidz90 i might use that flex-hose idea after all if i happen to own the correct lengths for the rear wing holders, this might help with the weight in the rear, if anyone has more ideas on how to reduce weight in the rear, i would love to hear! (that's what she said) Adding weight to the front IS pretty similar to a paper plane since the bulk of the paper is folded into that area on most designs (aka COG in front of COL, google it if you like the technical info behind it) but adding weight to a plane feels counter-intuitive, and at what point is this a dart with wings? What would you rather see? a slow short glide or a faster longer one?

 Good.. now that i have found a nice way to over-complicate a seemingly simple project, back to work!

More later..

 

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This is one of my favorite tc-15 projects. Very original and maybe it can actually float / fly eventually. Keep up the good work 👍.

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I'd try to find a way to connect both sails to single axle, effectively halving the weight here. It would be less rigid, but less mass = way slower speed = smaller forces. The classical, triangular paper airplanes work well ONLY because the wing loading (e. g. mass divided by wing area) is small. One can test this by adding mass to the paper airplane while keeping the COG - the speed (and the so-called Reynolds number) will increase and at some point, this type of wing will just refuse to work, basically producing more drag than lift.

 

You are right that reducing mass at the rear is critical - every gram at the rear means few additional grams at the front to keep COG. Unless the front sticks out far away, but that tends to destabilize the aircraft. Flex hoses are worth trying. Alternatively, maybe hold the rear sail tips with rope only?

Edited by Davidz90

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How about this: if you put the sails in-between the 6536 “Axle and Pin Connector”, but use 2780 “Pin with Friction” to connect the 6536 parts (if that is actually possible with the sails between two 6536), or 3L axle with some bushings. Then you won’t be needing the 41677 “Liftarm 1 x 2 Thin” lengthwise. So that would be significant weight reduction including ditching the tow balls. Basically you will have two separate wings joined together, only friction locked, not form locked like they are now. But that will also significantly deform the wings, so it may not be the best idea.

Also have you tried testing with those rear axles lowered in the same plane as the longitudinal axles? It will change the shape of the wings, but I don’t know what it will do to the flight performance.

wing%20holders.png

The sale will go in-between LBG and DBG part.

Edited by pagicence

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