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Author Topic: 2019 Elastic Launched Glider  (Read 1718 times)
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applehoney
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« Reply #25 on: September 11, 2018, 09:37:07 AM »

....... and don't leave the glider in back of the car in hot sun ...you may find the noseweight in a soft soggy mess on the floor underneath the fuselage.   :-(
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flydean1
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« Reply #26 on: September 11, 2018, 09:57:28 AM »

I use plumber's putty, from the local ACE Hardware store.  One coil lasts a lifetime.  Better yet is lead tape from golf suppliers.  It's adhesive backed and easy to cut tiny amounts for fine trimming.  I would argue that lead is "malleable".
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Olbill
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« Reply #27 on: September 11, 2018, 10:04:48 AM »

The gliders I got from Mr. Ishii have what looks like masking tape as the nose weight. This works well but probably wouldn't be legal under the SO rules.
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Re: 2019 Elastic Launched Glider
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Olbill
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« Reply #28 on: September 11, 2018, 10:12:50 AM »

This question reminded me that my supply of clay has disappeared. I just ordered this from Amazon:

https://www.amazon.com/Sargent-Art-22-4000-1-Pound-Modeling/dp/B003FGVNPM/ref=sr_1_1?ie=UTF8&qid=1536675062&sr=8-1&keywords=Sargent+Art+22-4000+1-Pound+Solid+Color+Modeling+Clay%2C+Cream
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wlsguy
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« Reply #29 on: September 11, 2018, 01:44:55 PM »

Just got word from Paypal that my order of gliders from Guru Engineering just got shipped from Ohio.

I seriously hope the actual kits aren't represented by the photo on their website. Grain direction is important. Also, I'm having trouble with the idea that a piece of 1/8" sq balsa is really a great basis for a fuselage.

Hopefully I'll be proven wrong...

Hello, This is John from Guru. Thanks for your interest.

The last time the event was in rotation (2014), the average time per flight at Nationals was 12.5 seconds. The top flight was 32 seconds and the bottom was 2.5 seconds with a median of 8.3 seconds. More than half of the field used the Freedom Flight Glider with mixed results (evenly distributed between 3rd and 57th places). This was at Nationals with many of the best teams. I'm sure across the country flight times averaged much less. Obviously we all want to see better times, more successful flights, and a better overall opinion of the sport.

The Guru Glider was based on the design my teams used then (and they would have placed 7th at Nationals with typical 23-25 second flights). They didn't need the heavy fuse but the 1/8" balsa was a compromise to make gliders flyable for new students. The modifications are pretty simple; sand the flap area a little bit, change out the 1/8" fuse for 1/16"x 1/8'' fuse, and reduce the clay.

Of course, with as many experts here, many experienced teams will choose to make their own design but we strive to make an affordable design alternative.
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bjt4888
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« Reply #30 on: September 11, 2018, 05:10:41 PM »

Glider Coaches,

Actually, glider times in Michigan were better than at Nationals in 2014. My four schools used the design posted in the plans section of this forum and averaged 27.5 to 28.5 second flights in a 27 ft. Ceiling site (launches to about 25 ft.). The rules that year were shorter wingspan and lower weight but about the same wing loading for most designs. My average flights with this same design same flying site were 28.5 to 29.5 seconds. My teams finished 3rd and 4th at Michigan States that year due to very conservative flying (the other two teams overall didn’t get out of our small, very competitive Regional).

If you are interested, I wrote extensively about this glider in the Hip Pocket forum thread for 2014. The glider design, construction methods, testing methods, etc. borrows from Bill Gowen, Kurt Krempertz, Lee Hines, Stan B., Jim Buxton, Ron Whitman, Curt Stevens, and others.

Brian T
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bjt4888
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« Reply #31 on: September 11, 2018, 05:27:17 PM »

The 30+ second flights at Nationals in 2014 were in a higher ceiling site than what we used. If memory serves me correctly, ( which it sometimes doesn’t, so someone can correct me on this) the Nationals site was a 37 or 38 ft. Ceiling. As my student’s best flights averaged 1.14 seconds per ft. Of launch height, they should have been capable of 40 or 41 seconds at a 36 ft. Launch height at Nationals.

We confirmed this flight time capability at an AMA cat III ceiling contest later that year. The gliders were only capable of launching about halfway to the 65 ft. ceiling at this contest and flew 40 seconds. A couple of my students also built Bill Gowen’s Cat II record holder that year and, partially trimmed, they flew 54 seconds at this 65 ft. Ceiling site. The goal was the AMA Junior national record of two 59.5 second flights; didn’t quite make, but with another trimming session it looked possible.

Brian T
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Olbill
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« Reply #32 on: September 11, 2018, 05:54:12 PM »

I yearn for a return to the 2013 rules. 10g max weight, no minimum. Let the kids that are interested build real indoor gliders. The eventual champions were doing 30 seconds in a 22'-8" site in practice.
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jdpsloflyer
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« Reply #33 on: September 12, 2018, 08:33:50 PM »

Plane dimensions listed below

30 cm wing span max
3.5g to 10g weight
1.1 flight time bonus if the fuselage is longer than 32 cm


Roger L



Paraphrased:

Ballast may be any malleable non-metallic substance.

The launch handle(s), excluding elastic, must be less than 1 m long in any orientation, be supported completely by a participant,  be of a safe configuration.
(I think this is a result of a national a few years ago that used a mechanical launch device setting on the gym floor.)

The elastic used in the launch handle must be non-metallic and must be in contact with the glider throughout the launch.

Additionally:

Bonus of a 1.10 multiplier will be applied to the Final Score of any team that begins its 5-minute Flight Period in 1-minute or less.

No mention of chord or tail configuration is in the rules that I can see, or that the glider must be traditionally a wing/stab/rudder.  This opens designs to canards, deltas, twin wing (canard slightly smaller than the 30 cm main wing, etc.  Lots of room to imagine for the kids.  Only time to settle on a good performer as the limiter.  I expect this will come down to traditional designs on the plans pages or combinations of them.

What about elastic?  Any thoughts on that?  Like size for given weight/height achieved or flight characteristics/bunting/roll ... 

All the planes produced in 2014-15 would meet requirements with dihedral changes to meet 30cm span.  I think the min mass was 3gm so ballast would be required and perhaps cg adjustments.

Slopoke
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jdpsloflyer
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« Reply #34 on: September 12, 2018, 08:37:43 PM »

Coaches probably need to ask SO officials about non traditional designs and weather they will be allowed.

Slopoke
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bjt4888
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« Reply #35 on: September 12, 2018, 10:39:17 PM »

Jdp,

My teams worked pretty hard on a canard glider several years ago, including a couple variants with largish foreplane surface area, with little success. They flew ok and with the canard bonus that year they would have been moderately competitive. I would recommend focusing on a traditional design or, better yet, a flapper design, and having the students practice a lot. Probably you already know this, but the fine trimming of the best decalage setting and determining the best bank angle and inclination angles for launch takes a fair amount of time. Every version of the same glider that my students built over the years required slightly different final trimming for best duration. I described this some in the previous year’s Hip Pocket threads. Sorry if this is already stuff you know about.

Brian T
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Olbill
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« Reply #36 on: September 12, 2018, 11:03:44 PM »

There are glider builders out there who can build a glider to fly the way they want it to. I'm not one of them. I have to experiment endlessly to find out how to get the most out of each glider.

If any of you are interested in the finer points of glider design and performance I'd highly recommend the Facebook group "Everything about F1N". Also I'd recommend following or friending Mitsuru Ishii. ( 石井満 in Japanese ). Mr Ishii writes about glider design several times a week and what he writes is always interesting.
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jdpsloflyer
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« Reply #37 on: September 13, 2018, 10:25:28 AM »

Jdp,

My teams worked pretty hard on a canard glider several years ago, including a couple variants with largish foreplane surface area, with little success. They flew ok and with the canard bonus that year they would have been moderately competitive. I would recommend focusing on a traditional design or, better yet, a flapper design, and having the students practice a lot. Probably you already know this, but the fine trimming of the best decalage setting and determining the best bank angle and inclination angles for launch takes a fair amount of time. Every version of the same glider that my students built over the years required slightly different final trimming for best duration. I described this some in the previous year’s Hip Pocket threads. Sorry if this is already stuff you know about.

Brian T

Brian,

I agree that traditional gliders are the best solution with the limited time we have to spend with our kids.  My teams flew flappers, polyhedral, and other 'traditional' ones three years ago.  Additionally, with all the refinements that Olbill and the others you have mentioned that have evolved over the years, there is no need to re-invent the wheel.  I was pointing out the imagination of middle school kids to experiment with this years rules.  I can "tell" them what is best, however I think they learn better through experiment and guidance. With gliders I have more time to do hands on learning with them since gliders are simpler and easier to build.  We build from balsa sheets and plan templates that the kids draw with examples from the plans forum.  Each team can settle on their favorite design based on their abilities.

I have built aver 40 "demonstration" models over the years and can use those to guide the kids to a good design.  The most successful ones were based on Olbill's record setting models with some simplifications to make it easier for the kids to build.  I have to pull these out to select the ones that are still flyable.

Here's to another good year in SO.

Slopoke

P.S.  Thanks Olbill,  I signed up for the Facebook group you recommended. At my age I need to re-educate myself all the time.
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Olbill
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« Reply #38 on: September 13, 2018, 11:23:15 AM »

This year there is no chord limit. I would suggest looking at state of the art F1N-150's for some ideas of new ways to go.
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bjt4888
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« Reply #39 on: September 13, 2018, 03:50:20 PM »

Jdp,

I agree, the simplicity of the glider construction allows for some fun experimentation for the students. 40 sample gliders is quite a lot. Have fun.

Bill,

Thanks for the info on Ishii and the F1N info and ideas.

Brian

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Little-Acorn
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« Reply #40 on: September 15, 2018, 12:58:47 AM »

Just got word from Paypal that my order of gliders from Guru Engineering just got shipped from Ohio.

I seriously hope the actual kits aren't represented by the photo on their website. Grain direction is important. Also, I'm having trouble with the idea that a piece of 1/8" sq balsa is really a great basis for a fuselage.

Hopefully I'll be proven wrong...

I just got mine today from Guru (four gliders in the kit), and built one exactly according to the instructions. The wood looks good, flat and straight, no warps or unevenness in density or grain. Laser cutting is wonderful (as Ziegler's is). Grain in the wing is spanwise, the "correct" way you'd expect. In the stabilizer it's diagonal, which looks a little odd but I don't think will cause any problems. In the fin the grain is nose-to-tail, exactly parallel to the bottom where the fin is glued to the stab. I would have expected it to be 90 degrees different from that, pointing straight up and down. Should fly fine as it is, but I'd guess this will be the most-easily-broken part of the plane.

It's a flapper, with two wing panels (of course). Each panel is a single piece of 1/32" balsa. They join together at the front half of their chord, with the flaps (i.e. the back half of the 1/32" panel) hanging freely at the back half. The wing is cambered at the front half where they join, by a curved two-layer balsa former.

The one I built came out at 3.84 grams, before I put any ballast on the nose or anywhere else. But without that nose weight, it balances about 1-1/4 inch behind where the instructions say it should. The instructions go on to tell you to put weight in the nose until it balances at a mark in the middle of the wing. I did, and now it weighs 4.25 grams.

Flight tests tomorrow.
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Little-Acorn
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« Reply #41 on: September 15, 2018, 11:58:44 AM »

I just got mine today from Guru (four gliders in the kit), and built one exactly according to the instructions. The wood looks good, flat and straight, no warps or unevenness in density or grain. Laser cutting is wonderful (as Ziegler's is). Grain in the wing is spanwise, the "correct" way you'd expect. In the stabilizer it's diagonal, which looks a little odd but I don't think will cause any problems. In the fin the grain is nose-to-tail, exactly parallel to the bottom where the fin is glued to the stab. I would have expected it to be 90 degrees different from that, pointing straight up and down. Should fly fine as it is, but I'd guess this will be the most-easily-broken part of the plane.

It's a flapper, with two wing panels (of course). Each panel is a single piece of 1/32" balsa. They join together at the front half of their chord, with the flaps (i.e. the back half of the 1/32" panel) hanging freely at the back half. The wing is cambered at the front half where they join, by a curved two-layer balsa former.

The one I built came out at 3.84 grams, before I put any ballast on the nose or anywhere else. But without that nose weight, it balances about 1-1/4 inch behind where the instructions say it should. The instructions go on to tell you to put weight in the nose until it balances at a mark in the middle of the wing. I did, and now it weighs 4.25 grams.

Flight tests tomorrow.

OK, it's morning, just did the first test flights and adjustments.

First few flights with no changes from the above, swooped up and stalled once or twice each flight. Looks tailheavy. On the second flight, the bottom of the nose hook broke off (I was flying in our asphalt cul-de-sac, early morning with no wind). The grain of this nose hook is also front-to-back, not vertical. It's two small pieces of balsa, both with horizontal grain, glued together like plywood. It broke along the grain. Since the glider apparently needs more weight in the nose, I replaced the hook with a D-shaped piece of 1/16" birch plywood. That hasn't broken since.

Added nose weight until it glided flat with no stalling. It has a VERY pretty, flat glide. Launched as flat and glide-like as possible, by hand from eye level, the best time I got was about 4-1/2 seconds in a flat, non-swooping-or-diving glide. That suggests to me that if I can get it to transition well (a BIG "if") near a 26-foot ceiling, it would then take 22-23 sec to reach the floor from that point. Not bad for a glider just starting its trim/test phase.

Launched gently with the simple launcher provided (Guru advertises a more complex one if you want). Best flight got up to maybe 20 feet, bobbed a little, then that nice flat glide, total time 14 seconds. It carried a lot of speed after transition, didn't slow down to that nice-glide speed until it was at eye level, I have to work on my launches.

With the replacement nose hook and no ballast, the glider weighs 3.93g. It needed 0.59g of clay in front to get that sweet glide, total weight 4.52g. It now balances 7mm forward of where the instructions said it should (where it used to swoop and stall), balance point is now 173mm from the nose.

Overall I am very pleased with this glider, especially at this early stage of trimming/testing. Later the above numbers will probably change as I dial it in, but I don't think they'll change very much. Well, that's a major guess, I don't have any experience with ELG, mostly Wright Stuff last season plus a lot of flying Stratos and Stunt Flyers 50-plus years ago, and every model imaginable in between.

So far so good. Grain direction was a problem in the nose hook, that's the part that takes the biggest beating obviously, both in launch and landing, we can't always fly in gyms with smooth wood floors during testing. And if I have to warp the fin for directional control as the instructions recommend, that could prove difficult with the odd horizontal grain, but so far haven't needed to. It makes a nice 20-25 foot circle with that sweet glide, right off the building table.

Nice plane, John. You mentioned possibly sanding the flaps. Others here have mentioned this for their designs too. Can you elaborate on this for a beginner like me?
« Last Edit: September 15, 2018, 01:18:20 PM by Little-Acorn » Logged
Olbill
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« Reply #42 on: September 15, 2018, 04:00:51 PM »

As you have figured out the grain on the nose hook and the fin should both be vertical.
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wlsguy
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« Reply #43 on: September 15, 2018, 11:07:16 PM »

Thanks for the feedback.
I guess I use more glue when making the nose hook “sandwich” and haven’t had the same issues with the nose hook breaking. That being said, I adjusted the rib sheet to rotate the nose hooks 90 degrees for added strength on future kits.
As far as the fin grain direction, my students always experienced trouble with the fin splitting along the grain when it was vertical so we thought out of the box and flipped the grain to longitudinal. It made it easier to wet and adjust without splitting. While I have never had an issue with fins breaking, 2 are included with each glider just in case.

As far as making it lighter: we replaced the fuse with a 1/16 x 3/16 balsa stick, used only 1 nose hook and wing support (both reinforced with glue), sanded the rear half of the wing to approximately 50% of the 1/32 thicknesses.
These changes may be too much for the beginners but still gives the more experienced students something to adjust to make the glider their own. I plan to make a video of the changes soon.
Thanks again for the feedback because we are always trying to make a better kit for happier students

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« Reply #44 on: September 21, 2018, 04:03:43 PM »

I did a fair amount of flying of the Protégé on Saturday and got some nice footage:
https://youtu.be/dSyZ6Cz_KU4
Finished the day with a string of flights in the low 20's, so it's definitely a competitive airplane. I think a well coached team spending several focused sessions with it could fly a fair bit longer. I was only flying the one plane, and it has some structural issues from me messing up the stab and then doing a trimming video over wet grass.

One of my customers reported 25 seconds in his first flying session. A definite reminder that my trimming skills with flapped gliders are sub-par. Kinda ironic that I can design a kit that others can fly extremely well with very little effort, but I can't make I fly nearly as well. Weird.
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Ross J
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« Reply #45 on: September 30, 2018, 09:47:16 PM »

I will be coaching a Sci-Oly team this year and will follow this thread closely, and join the F1N page on Facebook. I'm thinking about designing a WIF 7 for the aforementioned rules with a 2mm carbon rod fuselage and unreinforced wings. I've built and flown my own WIF 7 as per Bill's plans and think with a few simplifications it could be a good model for these beginners. If those on this forum have any suggestions I'm open to them.
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Olbill
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« Reply #46 on: October 01, 2018, 06:21:10 AM »

I will be coaching a Sci-Oly team this year and will follow this thread closely, and join the F1N page on Facebook. I'm thinking about designing a WIF 7 for the aforementioned rules with a 2mm carbon rod fuselage and unreinforced wings. I've built and flown my own WIF 7 as per Bill's plans and think with a few simplifications it could be a good model for these beginners. If those on this forum have any suggestions I'm open to them.

Sounds like a good start. I haven't done anything with a glider so far. My thinking is something along the lines of an enlarged F1N-150.
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« Reply #47 on: October 03, 2018, 10:26:09 AM »

Here's a tip I posted in the WIF7 SO thread:

It's very important to have a way of adjusting the incidence. With a 3.5g weight budget you should be able to use screws to attach the wing. A small foam pylon under the wing will give you the ability to make small adjustment by tightening one or the other screw. If the adjustment needed is out of range for that method then it's easy to remove the wing and sand the foam pylon for a larger adjustment. For a 12" glider I would use 3/48 nylon screws. Leave enough meat in the fuse under the wing to drill holes for the screws. Drill the holes undersize and then tap the holes with the screws you're going to use. Harden the threads in the balsa with thin CA.
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« Reply #48 on: October 10, 2018, 11:01:23 AM »

Apparently some of the ELG contests this year are being held in higher ceilings, so I came up with a Carbonette variant which should work well in those sites. It trims out super easily.
https://www.youtube.com/watch?v=k4gZhRKq8Yc
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« Reply #49 on: November 02, 2018, 11:07:31 AM »

Any suggestions, tables or threads on rubber size, weight, loop length for gliders of various weights and launch heights?

This years rules have loop length as a required data item.  I think that would correlate with pull back, launch height and glider mass to explain the energies involved for SO CLG (it is science after all, as well as fun)

I'm using Olbills diagram of bunting to explain the process and interaction of incidence, decalage, and flaps for some more advanced students to explore.  I have 4 students returning from 2 years of Wright stuff (8th graders) who have an interest in tuning higher performance gliders.

My younger students are learning to build from scratch with sheets of balsa.  Building, breaking, building, trimming, breaking, repairing, trimming, flying, breaking,  and so on and so on ... fun for all.  Now if I can get them through the point and shoot phase.

I'm using heavier balsa for early models.  When they get better at building and flying we go on to the lighter (and more expensive) stuff.

As an introduction, I had them launch some of my 2014-15 gliders the first meeting, what a hoot!  I'm running low on demo models.

Jerry
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