Elastic Launched Glider C

[wlsguy]

Just finished a flying session with the local HS team. I can confirm what Jeff says about the longer nose moment. The team has new a glider that originally had a shorter nose. They began trimming by starting with slightly up elevator that allowed the glider to stall and not dive. After many adjustments, the glider would transition after a vertical launch but had an issue with a tiny stall that happened about every 5' while in orbit. No combination of very minor nose weight or up elevator seem to cure the issue.

After a short conference, the team members, head coach and myself agreed to lengthen the nose with a splice by 10% added length. This was done with long angle splices and reinforced with thread and glue. The extra nose moment adding 10% did the trick. Less clay meant the glider was still around 3.2 grams but... the best time before modifications was 24 seconds. The best time after the longer nose became a consistent 30-31 seconds. The gllider now flies like its "on rails" with no hint of the intermittent stall. It still has up elevator, slight down aileron on the starboard wing, 1 degree left rudder. Launch is near vertical with slight left wing tilt.

Hope that helps..

Good times. How high was the ceiling?

[fifty_missions]

Ceiling height- 28'-5" to the bottom of the girders. Glider flew below the girders in a 20'+ orbits (3 orbits/launch). Temps were 63 degrees and humidity 51%. Loop on launcher is 1/16' cross section, 7" loop.

Glider is now set to fly under a 60' ceiling this coming weekend. The team is hoping for a couple of 50+ second flights. The new longer nose allows this glider to be launched with high velocity in near vertical "penetration" .

[fanjiatian]

Won States today with a combined flight time of 42.8 seconds under a 28 foot ceiling (more like 25 ft without the net or girders)

[Lake101258]

I made a plane that gets about 16-17 seconds and its mass is about 4 grams. Im hoping that with the design I can get 20+ if I take the mass down. Any tips on how to take mass off?

[jander14indoor]

Look back up this page for previous responses to that question?

Jeff Anderson
Livonia, MI

[Asteroidea]

Many many pages back someone posted a link to the Feathershooter plan. I've recently built it and even though I haven't had chance to really launch it yet, when I hand glide it the glide is all over the place. It'll dive to the ground after a short distance and instead of gliding on a horizontal plane, one of the wings tilt towards the ground and causes it to crash. I've tried putting some weight on the opposite wing to counteract it but it hasn't helped too much. Any tips on how to fix this? Thanks!

[fifty_missions]

Having built and flown this design, I can guestimate some of the issues...
This glider has been designed for 2 gram total WITH CLAY and chances are yours is twice that weight
Here are other issues...
#1) Are the wings sanded to both the right weight and thickness especially in the flap area? If not, the flap is not working on launch correctly and not flaring flat to launch straight. It will always have a tendency to pitch up or pitch down (climb or dive) until corrected.
#2) Are the fuselage meaurements as written on the plan? if they are too short, it will be always be pitch sensitive.
#3) Did you modify the nose to meet the SO rules? Do this and it will automatically add mass to the nose.
#4) What density and grain of wood did you use for the fuselage? I suspect the fuselage is too weak for the stabilizer/fin mass and it is fluctuating due to those loads during launch and slow down.
#5) Is the leading edge of the wing slightly lower than the aft section of the pylon? This will cause a terminal dive sickness that can not get corrected unless disassembled and corrected.
#6) How much dihedral is there? If there is not 1.5" high on each wingtip, it will be unstable in the roll axis.
#7) Use 1/16" cross section rubber with a 7" loop for launching. Any larger rubber may damage the glider on launch.
I recommend giving some "up" elevator to the trailing edge of the stabilizer and adding more clay to the nose until the glider is stable. Without a flaring flap and equally cambered wings, the glider will be sensitive to higher speed launches. It may be the you can launch the glider in a vertical attitude but it curves down forward and dives. Issues above, #2, #4, #5 can all contribute to this issue. Again, adding up elevator and more mass to the nose should alleviate some of this. Gliders are more stable nose heavy and slight up elevator so worth those mods to try.

Once the glider stable than you need to address the orbit possibly by bending the trailing edge of the fin (rudder area) to the left to gain a left flying orbit.

Frankly, this is an expert glider meant for someone who has built and succeeded with flying these indoor gliders for about ten years. A simpler to build design may have a slightly shorter flight time but will be much easier to trim for competition flying. Contact Joe Simmons at IL Science Olympiad and he can forward a more reasonable design with photo instructions.

Good Luck.

[Asteroidea]

Mine is actually around 2.7ish grams with clay.
Thanks for your response though!
#1 I've double-checked with a micrometer and I believe the flaps/wings are sanded to the same thickness
#2 Yes
#3 No, I usually do this last after I've finished trimming. I use a very very thin piece of wood, mass it and then take off the appropriate amount of clay
#4 I have no idea...should I add some carbon fiber to strengthen it?
#5 I don't think so
#6 none....the plan didn't call for any so I will go fix that
#7 Will do

Thanks for you help!

[fifty_missions]

Indiana State Competition, Final results on Glider, Top 5, based on two best flights..
1) Whiting HS- 33.10 & 29.50 total of 62.60
2)Valparaiso- 25.50 & 26.80 total 51.50
3) Carmel- 24.51 & 19.93 total 44.44
4) Chesterton- 22.20 & 19.60 total 41.80
5) Bloomington South- 17.40 & 16.30 total 33.70

The flying site is relatively high (62'+) with virtually no drift all day and has the footprint of a soccer field. The only worry was the girder clutter at the ceiling but no teams came within 20' of the ceiling. Whiting won with a low ceiling (AMA Cat I) single dihedral design while Valparaiso used a more conventional polyhedral design. None of the five schools in ELG move on to Nationals. Hopefully the two teams that do, Munster and Bloomington North will be able to figure out their solutions before they go to Wright State in May.

An interesting side note, an 8th grader from Thomas Jefferson MS was cooling his heels waiting to do his official flights in Helicopter and put up two unofficial glider flights of 36 and 40 seconds. Rumors quickly spread that he was a "ringer" for Valparaiso HS but was just out having some fun in a very nice flying site.

Good Luck to both Munster and Bloomington North.

[piimasta314]

I made a plane that gets about 16-17 seconds and its mass is about 4 grams. Im hoping that with the design I can get 20+ if I take the mass down. Any tips on how to take mass off?

You can try sanding down extra splinters that are adding unnecessary weight. I don't know your design but I'm pretty sure there will be places that you can shrink or shorten your glider to make it lighter. Also you can try using different materials, like lighter wood, and get rid of any excess glue or whatever if you can.