[TC15] Paper Plane, a Functioning Glider

[Marxpek]

thanks once again for your input! I have mixed up your ideas a bit and came up with this:

a flex cable (longest i seem to own, seems 19L) that supports the entire rear section of the sails, the axle to pin connectors have the "open center" style black friction pins that allow flex cables to pass through and allows for sideways adjusting (aka steering..) i doubt i can get any lighter by design, but who knows.. some suggestions have been amazing and lead to this already!  I feel as if the wings are a bit to bulged up by this design, however.. this resulted in my best indoor flight results yet, if that was because of the weight reduction or the wing position is hard to tell. I will have to search in some sets for other sizes of flex cable, 2 of a smaller size on either side will work as well, but 1 long one will be more easily adjustable. anyone familiar with the longest flex cables available?

@pagicence i tried what you suggested, wedging the sails in between, but the friction pins do not want to stay together because of the extra millimeter (or so..) of sails in between and the axle-bush solution loosens up, so the connection is not solid (for long) and it also seems to pinch the sails, making small folds, so i did not go on with that idea, however your little rendering plus the suggestion to lower the rear is what gave me the idea for putting a flex cable into that, so loving the input nevertheless! 

I am now looking into reducing the frame even further, a single 24L axle in the center would be great, connecting the sails to a single axle symmetrically is not that easy, but maybe doable. your suggestions and idea are more then welcomed for that of course!

more later. 

[MattL600]

Can we have a video of i flying?

[Marxpek]

Some changes to the design, I brought the entire front wings about 4 studs forward, shifting the COG more to the front and increasing the wing area.

It added a set of connectors and tow-balls and some  axle-length to the design, but since it was all in the front, it drastically improved the COG.

On 12/20/2018 at 8:53 AM, MattL600 said:

Can we have a video of i flying?

I have made some fast and dirty shots flight shots with this design for those interested, but for those who do not like spoilers i will hide the video.

Spoiler

 

Looks like i will have to search for a good indoor spot to shoot a video, at home i do not have a good spot to film and throw the plane, even with minor winds it has lots of trouble gliding stable, so at the start of winter, in The Netherlands, the chance of having a day without any wind at all, is slim at the very best..

I am still looking into making the design lighter by going to a single axle frame, but the weight in the front will most likely be similar, so relatively more weight in the rear mean that the COG shifts backwards again, so this thinking about how to overcome this, i am considering leaving the entire rear unsupported from the frame, i have an idea for it that might work, but crashes (which are common of course) might more easily do damage to the sails with that setup.

More on that later.

Edited December 22, 2018 by Marxpek

[pagicence]

If you spread the wings in the back (with 24L axle instead of 19L hose), how will it fly then?

[Didumos69]

Can't you attach it to one of your fast buggies and see if you can make it float like a kite? Perhaps in a sports hall?

Edited December 22, 2018 by Didumos69

[Marxpek]

12 hours ago, pagicence said:

If you spread the wings in the back (with 24L axle instead of 19L hose), how will it fly then?

I do not fully understand, there was never a 24L axle in the rear that is not possible either (the holes in the sails do not allow axles through), you mean the system i had earlier, with 2x 10L axles? i have not yet tried this with the new front end shown in my previous post. I will try it, but i expect somewhat worse results, since the COG shifts backwards with that setup since the rear will be heavier.           0

3.

10 hours ago, Didumos69 said:

Can't you attach it to one of your fast buggies and see if you can make it float like a kite? Perhaps in a sports hall?

This actually crossed my mind and i have my MOC " Supersoninc RC Buggy"  the 8475 / 8366 tribute buwizz tribute build, sitting on a shelf unused for too long long, it would be a perfect candidate for it, however, i think it is asking for troubles and crashes, so i might do this when i have all the shots made for a video on regular gliding, to avoid damage before that ( i have 2 sets of extra sails, but i was hoping to use those for pictures or backup ) it, would be a fun extra for the video.

[Marxpek]

I have finally managed to make the single axle frame and i am pleased with the results, turns out a pneumatics part was the answer.

 

Early tests show very promising, a LOT more lift, but as expected a bit tail heavy now, making it fly up sometimes, loosing speed from the climb, then stalls, when i weighted the front a bit more i had even better results, but i am closing in on the final design with the single axle build, it seems to want to glide fairly stable by design, but one thing i did learn while doing this: you also need to get a feel for the plane and how it should be held/thrown, this design with to much weight at the rear and glide pretty good when you thrown it softly at a slight angle downwards often doing a small air-hop from lift, but i would like a nice parabolic arch with a little air-hop from lift at the end, or at least after the peak, showing the lift it generates from the increase in speed from a drop, if possible... (that's even hard to get in a paper plane, but hey, let's aim high here..)

More later, and Happy Holidays to you all! 

[pagicence]

I'd say you nailed it. Simple and effective.

[Megamech]

Why not use the half bush with the pneumatic connector? 

[Marxpek]

 Closing in on the final design:

This rear setup allows me to make subtle changes to how the rear wings stand by either twisting the number 3 angled connector or the cross-hole to cross-hole connectors holding the ball joints, by twisting the number 3 connectors you can increase or decrease the lift (and drag) getting this positioned equally and and correctly is crucial for a decent flight. This setup also increases the dihedral angle of the wings, giving it more stability. 

By twisting the ball-joint and the cross-hole connector i can flare up or flare down the ends of the wings so I can somewhat counterbalance the lift for a straight flight.

Also the front wings now have a way to make minor adjustments to how they sit (the curling back is still somewhat of an issue..). The crankshaft is another strange, but great find here, it perfectly fits the pneumatic connector, and by twisting them up or down you can slightly re-position the front wings.

Brings me to: 

On 12/25/2018 at 3:04 PM, Megamech said:

Why not use the half bush with the pneumatic connector?

This indeed was the obvious thing to do, but i tried 4 different type of half-bush  that i have (of all ages, including the super old serrated ones) and none of them seem to have enough clutching power on such a small surface area, but i did find a better solution, i did have to rob my daughters  Lego Friends collection for it but hey.. i think they part is called " stud with open top", great clutching power and holds the sails better, would be nice if i can get them in black, i do not know if there is any weight difference, i have ordered a precision scale, that should arrive Friday, with that i can improve the weight a bit further maybe, as i am "eyeballing" the weight of some parts and solutions now.

 

 

Being able to adjust how the wings are set makes all the difference, but you really have to tweak and check the wings every time you throw this, everything is out of balance after each flight/crashlanding.

I hope to finalize the design soon.

More later.

Edited December 26, 2018 by Marxpek

[Megamech]

Do you really need to make it as light as possible? If it becomes too light then it may have some other problems.

[Marxpek]

8 hours ago, Megamech said:

Do you really need to make it as light as possible? If it becomes too light then it may have some other problems.

Well, yes.. less weight means less gravity acting on it, means it needs less lift to glide, less lift needed means i can set the wings in a position with less drag, less drag means more of the thrust goes into forwards momentum in stead of lift (more speed also increases the lift), means a longer/further flight. And i really want to make the design as good as possible, 

And it is not likely i will ever be able to make this lighter than a real paper plane of a similar size and outdoor flying any paper plane with some wind is asking for problems anyway, so i am not too worried about problems from it becoming too lightweight. i also already had to add a little bit of weight in the front to balance it out, while all the "weights" do have another function besides being a weight, i am still looking into loosing some weight, especially on this connection, maybe someone has a suggestion for it:

this is by far the heaviest connection to hold a sail in the plane, it even has a unused pinhole (and now that i look closely at this picture 1 heavier and 1 lighter version of the towball-pin..), something i really do not like here, I've been searching for a lighter (symmetrical) solution for this but i haven't been able to find a solution yet, if anyone has a suggestion for it i would be more than happy to try it.

More later.

[Seasider]

Would a 3L axle and pin connector 32184 with axle ballpins 2736 and then held on your central axis by half bushes ... would that be lighter?

i agree with one of the previous comments that ultimate lightness may not be your goal. But a good weight balance will be.

[1gor]

You can always calculate total weight for some 'subsystem' simply by using weight of several pieces in your construction. On BrickLink page for every part there is item info containing years of release, weight and size...

Wen you got some satisfying solution just calculate weight and you will see what is doable 

[Marxpek]

 

8 minutes ago, I_Igor said:

You can always calculate total weight for some 'subsystem' simply by using weight of several pieces in your construction. On BrickLink page for every part there is item info containing years of release, weight and size...

Wen you got some satisfying solution just calculate weight and you will see what is doable 

I have considered this, but the total is at 32 grams now according to my kitchen scale (goes by the gram), so every gram lost or missed by the scale is a 3% weight difference at the moment, quite substantial, when i weigh a subsytem of a few pieces they tend to be only a few grams or not measureable with my kitchen scale, the scale i ordered should be able to weight per 0.01 grams, bricklink data shows 0.1 grams for a lot small parts, something i do not trust. And since these scales aren't that badly priced and the wife might be able to use it for measuring spices to make me better meals, so i just ordered one to be sure and make my life easier, not having to eyeball or calculate weights from (inaccurate?) bricklink data.

in the meanwhile i did come up with a way to replace the connectors from the post i made earlier today, using the pneumatic T-piece:

I think it is a bit lighter by design (from eyeballing it), but it is not symmetrical, something i do not like, something i do like about this is the fact it gives me the possibility to adjust the rear wing a bit more, the half-bushes should be replaced with the stud with open top.

more later

[1gor]

Your solution could be symmetrical if you use technic cam piece, but it is 2 studs deep which often cased me a problem of to wide vehicles...

This is part that I was referring.

https://www.bricklink.com/v2/catalog/catalogitem.page?P=6575#T=C

BTW my wife uses fingers for appropriate spices doses, so there is not enough precise kitchen scale...

I must admit your project is more and more interesting

[Marxpek]

7 minutes ago, I_Igor said:

Your solution could be symmetrical if you use technic cam piece, but it is 2 studs deep which often cased me a problem of to wide vehicles...

This is part that I was referring.

https://www.bricklink.com/v2/catalog/catalogitem.page?P=6575#T=C

BTW my wife uses fingers for appropriate spices doses, so there is not enough precise kitchen scale...

I must admit your project is more and more interesting

Thank you!, i realize this build does not look very impressive because of its simplicity, but in practice making it really glide is a bit of a task, a task I've really grown to love!

I tried to fiddle with that part, but i did not find a way to make it fully symmetrical with that, the whole issue is the single axle frame, the connectors cannot be on the same place, obviously.. so i would have to flip one of them over to make the weight distribution evenly on left and right, but then the weight would (be ever so slightly) more to the front on one side and more to the rear on the other, just like my previous picture, if you had another idea how to use this part i would love to hear.

however i found another symmetrical and even lighter solution with this setup, using an ancient half-plate, it does slightly increase the drag tho, there is always a con it seems..

more later..

[1gor]

Last one is symmetrical, but you will have to test it to see if this construction is sturdy enough. This plate has axle hole in center so it is usable.

Regards

[Marxpek]

2 hours ago, Seasider said:

Would a 3L axle and pin connector 32184 with axle ballpins 2736 and then held on your central axis by half bushes ... would that be lighter?

Sorry i missed your post at first..

I have tried this setup earlier on since I also thought it was lighter, but the connector can rotate on the central axle (even when clamping it between serrated bushes) making the wings flap about loosing all stability.

and i agree that making it lighter is not the main goal, balance is indeed, however decreasing the weight will make it glide further and longer, planes are built as light as possible for a reason, to make better use out of it's thrust, go further on a drop of kerosene or in my case: go further on a single throw. After the weight reduction the re-balancing is up again.

[Marxpek]

So finally my new scale arrived! and after redesigning i can report the current and final design weights in at a whopping 28.39 grams, which is about 4.5 gram lighter than it was before the redesign (3rd frame from above on 2nd pic):

I have been experimenting with a flex-hose frame, which helps a lot with the weight, i have tested several designs, also designs i did not get a picture off sadly, one of those was a frame built only from flex hoses but this was way to flexible so it was rejected right away, here are a few other frame designs i have rejected:

Most designs had a regular axle in the front and a flex hose at the rear for reduced weight, and this seems to be the answer to my COG issues, reducing the weight in general, but more importantly, the rear. So here i would like to present the final design:

With this setup i am able to set the wings in several positions, changing the flight characteristics, getting a feel for how the wings should be positioned is vital, but i am getting better at it. This setup also increases the dihedral angle of the wings, since i have lowered the COG with the rear wing mounts, increasing stability. The plane seems to be balanced nearly perfect with the current frame.

I will replace the few brown pneumatic connectors for grey ones and i think i will build a few of these planes to make it easier to shoot a video.

More later.

 

 

[mocbuild101]

10 hours ago, Marxpek said:

So finally my new scale arrived!

Wait, those are your new scales?  I certainly wasn't expecting something like that... 

[Marxpek]

13 hours ago, mocbuild101 said:

Wait, those are your new scales?  I certainly wasn't expecting something like that... 

Look who is sharp today! I was already wondering who would comment on the antique scale in the picture, glad i could count on you , this was a little joke of course, so here is the actual picture of the new scale and the plane 

seems i lost 0.01 grams compared to yesterday (or air pressure is a bit lower today, or perhaps a small fluctuation in the space-time continuum, or I just simply misread it yesterday..)

Edited January 4, 2019 by Marxpek

[mocbuild101]

On 1/5/2019 at 3:53 AM, Marxpek said:

seems i lost 0.01 grams compared to yesterday (...perhaps a small fluctuation in the space-time continuum...)

 Most likely there was a tiny amount of sweat from building on it, which dried up overnight...

[Marxpek]

On 1/6/2019 at 3:21 AM, mocbuild101 said:

sweat from building on it, which dried up overnight...

you are the romantic type, aren't you? 

Paper planes rarely fly solo, so.. more importantly: this will help me tweak and compare flight characteristics, and will make shooting video easier (less walking back and forth..) The search for a suitable location to throw these is still ongoing...It is not easy to find a big empty indoor space where they allow you to play around for a few hours with some cameras it seems.. but i am sure i will find something in the end.

More later.

[Marxpek]

3 weeks of silence in the thread, so here is an update:

I managed to find a enclosed entry to a parking lot/shopping mall where no one comes if you go on Sundays before 10 am, did that twice. I was also lucky enough to get a freezing, but nearly wind-still day to try outside and the results are better than i had expected. The video is done and out on my YT channel, i also did a cartoony little intro just to spice it up a bit, i hope you like it! And for those who do not want to get spoiled:

Spoiler

 

i called it the Lego "paper" plane - A17,  A stands for initial 2 designs i started with and 17 is the number different frame builds i have tried, how inspiring.. I know.. you might notice the plane got a little bit heavier, i ended up putting a bit more weight to the front of the plane, preventing stalls when throwing it "harder than gentle"

 I still need to make better pictures for it, plenty of time for that.

More later.