Elastic Launched Glider B

[brianv]

Is there an advantage to a long launcher with a pistol grip handle on the bottom as opposed to a simple stick? Thanks in advance.

[wlsguy]

Is there an advantage to a long launcher with a pistol grip handle on the bottom as opposed to a simple stick? Thanks in advance.

If the launch handle has gages or indicators for pullback distance, elevation (up/down angle), and pitch (left/right angle) then yes, it has an advantage.
If not, then probably no.

That being said, not everyone needs an elaborate angle / measurement system to be successful. Launching is a lot like a golf swing, if you can do consistantly, you have good results, if not, you end up in the water sometimes.

[homesciencenerd]

In most competitive states, what would be a top 5 time

[Bilbo McSwaggins]

Soo...


Would it be legal to build a launcher that rests on the ground?

I'm pretty sure the 2013-2014 National champion had a launcher that rests on the ground.

[jander14indoor]

Careful, while last years launcher was on the ground, rules changed. I don't have my copy handy so I don't know if it is directly legal, but with the 1 m length limit, hard to build like that now.

I supervised a contest this weekend. Two teams had long launchers with angle gages, they had a very consistent launch. The winning team had none of that, but had obviously worked hard to become consistent. The launcher very obviously managed their body position to have a consistent elevation, and their partner lined up behind and corrected the bank. Dead consistent launches, probably less than 3 ft variation in peak height. And their glider was well trimmed, out of 5 launches, only one had a little drop, less than 3 ft, during the transition.

Jeff Anderson
Livonia, MI

[bernard]

Careful, while last years launcher was on the ground, rules changed. I don't have my copy handy so I don't know if it is directly legal, but with the 1 m length limit, hard to build like that now.

I supervised a contest this weekend. Two teams had long launchers with angle gages, they had a very consistent launch. The winning team had none of that, but had obviously worked hard to become consistent. The launcher very obviously managed their body position to have a consistent elevation, and their partner lined up behind and corrected the bank. Dead consistent launches, probably less than 3 ft variation in peak height. And their glider was well trimmed, out of 5 launches, only one had a little drop, less than 3 ft, during the transition.

Jeff Anderson
Livonia, MI

It's in rule 3.g.. "1 m long in any orientation at launch" still seems like a lot of space to make a ground launcher.

[Bilbo McSwaggins]

I think freedom flight models are the best.

Based on data from Nationals for the past 2 years, there is no "BEST".
Of the 60 teams at Nationals, Freedom Flight Models have finished as high as 5th and as low as 59th. They are distributed in a normal pattern throughout the rankings.

The key points are:
1) Build consistent- Too many models were sloppy or had warps or issues which limited performance
2) Practice- If you expect to build a model and suddenly win, you are mistaken. This is not a contest of who can build the best glider. Taking and using data to improve your launch technique is what wins or loses competitions
3) Build Light- As with all of the flying events, if everything else is the same, the lighter glider will win. Just one word of caution, if you build so light your glider breaks every time your practice, your data or glider will have the issues from 1+2 above and you will perform poorly.

Thanks,
John Hance

But you can't build too light because the glider will not be able to go any higher after a certain height.

[Bilbo McSwaggins]

Just wondering how to determine the quality of the foam flaps. (I use freedom flight)

[fifty_missions]

Just a quick report on the Indiana State Finals. The ELG event was held in the Mellencamp Fieldhouse with a height of 60'. Thomas Jefferson MS won with all5 flights in excess of 38 seconds EACH. Their total score for 3 flights was 112. The second place team was 72. TJ would have won the event with just two flights. Thomas Jefferson won the overall IN State Competition and will be flying at Nationals in Nebraska (60' ceiling).

They did not use the Freedom Flight design as that design has too many inherent issues. These include the following-
1) It is essentially short coupled and the fuselage is too short with the wing's trailing edge too close to the stabilizer which makes the model very pitch sensitive (nose up, nose down)
2) With the fuselage is so short, many have not passed the go-no-go gauge length inspection as they have a tendency to bow slightly shrinking the length. Those teams get tiered below all others.
3) The foam has tendencies to warp.
4) The FFlight design works best under 30' but cannot climb any higher. Height is everything in this event.

Instead, the TJ team have been using a format that they developed based on the AMA Educational Videos as well as the AMA Glider website. Their glider was in the neighborhood of 5 grams, an all balsa model, with a fuselage at about 37cm long, wings in polyhedral format at 32 cm span. The longer length allows the tail surfaces to be slightly smaller than those on the FFlight version with just enough stability to handle the high velocity launch yet just unstable enough to allow a transition with minimal altitude loss. See similar model in the picture below-

Here is the video that helped them the most...

http://amaflightschool.org/diy/2015-sci ... nch-glider

Regards,
50 missions (and counting)

[fifty_missions]

The Freedom Flight design has short coupled fuselage. That's ok if you have 20 years experience in trimming gliders. I highly recommend building a new fuselage that is more like 35-36 cm long. In addition,
try sanding the tail surfaces so that the trailing edges are about 1/64" thick. Another trick is to check the incidence relationship between the wing (positive) with the leading edge about 1/2 a degree higher than the trailing edge. If you can manage to do the reverse on the stabilizer (negative) with the trailing edge 1/2 degree higher than the leading edge you will have a glider with a good set-up for launching and transition.

Light weight is extremely important. Build the glider just under 4 grams and with the clay ballast you should be just over. The thinner trailing edges in the tail surfaces will allow you to tweak some trim. To bend in UP elevator, pinch the wood on the the trailing edge of the stabilizer and bend the wood up no more than a degree (about 1 mm). You can use the same method to add more or reduce the turning orbit by bending the trailing edge of the fin (rudder adjustment).

There are more issues but I always recommend starting the glider with a stalling flight pattern. You can either add more mass on the nose or reduce the UP elevator. BTW, NEVER add down elevator!!

Good Luck,
50 Missions