Wright Stuff C

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DatSciolyBoi
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Re: Wright Stuff C

Postby DatSciolyBoi » October 28th, 2019, 10:52 pm

Just completed tryouts... :shock:
Chaparral Middle School -> Troy High School
Background in: Wright Stuff, Bottle Rocket, Mission Possible, Wind Power, Experimental Design, Elastic Launched Glider, Fossils, Mystery Architecture
Builder Cult Satanic Group .CO :twisted:
Co-Sassy of Game 138: Tanks and Turrets

Umaroth
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Re: Wright Stuff C

Postby Umaroth » October 28th, 2019, 11:02 pm

Just completed tryouts... :shock:
Bro how was it
Troy SciOly 2019-2020
Kraemer SciOly Padre 2018-2019
Dank Memes Area Homeschool Juggernaut 2018-2019
Kraemer SciOly Pretty-Much Head Coach 2019-2020
2020 Tryouts: Circuit, Code, Detector, DP, GeoMaps, Machines
SOLVI Events: Code, Detector, DP, GeoMaps, Machines

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DatSciolyBoi
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Re: Wright Stuff C

Postby DatSciolyBoi » October 29th, 2019, 6:50 am

Just completed tryouts... :shock:
Bro how was it
Decent, considering that I wrecked the plane day before yesterday. Maybe 4th place? That dude from last year is actually OP.
Chaparral Middle School -> Troy High School
Background in: Wright Stuff, Bottle Rocket, Mission Possible, Wind Power, Experimental Design, Elastic Launched Glider, Fossils, Mystery Architecture
Builder Cult Satanic Group .CO :twisted:
Co-Sassy of Game 138: Tanks and Turrets

bjt4888
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Re: Wright Stuff C

Postby bjt4888 » October 29th, 2019, 11:32 am

Eric,

It is party inherent in the airplane design, required by this year’s rules, that your best flights are characterized by rapid climb, short cruise and fairly long let down.

The very tiny propeller makes for difficulty managing horsepower output through the course of the flight. Usually, excessive climb rate would indicate that slightly more propeller pitch is needed, or slightly thinner rubber. However, more pitch will also possibly reduce horsepower too much during the letdown phase of the flight, so all phases of flight need to be monitored when making this change.

CG location and decalage can also affect climb rate when close to the extremes for stable flight for a particular design. The very small stabilizer In this years rules complicates evaluating CG as the airplane is very sensitive to changes (So, make changes in very small increments).

Another method of controlling climb rate is to induce roll during the initial climb. This is usually done by minimizing inner wing panel washin and playing with other turn settings. Roll can also be built into the design by minimizing winglet height or dihedral. This method is a little risky as poor roll stability can make the airplane not so great at recovering from upsets from bad air or ceiling hits.

Good luck to Luke with the fine tuning of your approach.

Brian T

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Re: Wright Stuff C

Postby bjt4888 » October 29th, 2019, 11:33 am

partly not “party”. Hard to keep up with crazy auto correct.

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Re: Wright Stuff C

Postby lechassin » October 29th, 2019, 1:11 pm

Brian,

Ref, induced roll: our wings have no twist, but we did find ourselves tweaking the initial climb rate by adjusting the rudder in tiny increments that don't affect the cruise radius. This tweaks the amount of launch banking (and therefore lift), especially to the left based on prop rotation. To the right there's not as much banking so we're having to also reduce decalage to control the climb. The rest of the flight suffers so it's a compromise. We haven't considered twisting the wings yet, that wouldn't be too hard for us the way the tips are braced.

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Re: Wright Stuff C

Postby ginajewelkim » November 2nd, 2019, 4:19 pm

What are the best or necessary materials?

bjt4888
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Re: Wright Stuff C

Postby bjt4888 » November 3rd, 2019, 6:29 am

Ginaje,

The teams that I coach (and other top teams) approach Wright Stuff partly as a materials engineering project. The density, weight, cross section and stiffness of ever balsa wood and carbon part is evaluated carefully and selected to provide adequate stiffness and to achieve correct CG and overall target weight (less than 8 grams).

Jeff Anderson created a basic example of “building to weight” that is part of this evaluation. This example in on this forum somewhere, but I can’t find it anymore.

Brian T

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Re: Wright Stuff C

Postby bjt4888 » November 3rd, 2019, 6:42 am

Eric,

Congrats again for your results to date and for the contribution to the forum.

With reference to your response about induced roll to control initial climb rate, you probably already know this, but the three methods I mentioned in my above posting are listed in the order my teams would approach. And, also I’m sure you already know, all three methods require multiple to many tested combinations (ex. Small reduction in rubber density or increase in prop pitch will usually increase circle size and reduce roll allowing, possibly, reduction is wing washin and/or turn setting changes which may indicate changes needed in CG and decalage; the stopwatch is the indicator of success; my teams completed about 600 test flights last year).

Also, if you are inclined, buying and learning to use a rubber stripper (not a simple task) is critical to reaching the top level.

Keep testing and having fun with WS!

Brian T

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Re: Wright Stuff C

Postby lechassin » November 3rd, 2019, 11:29 am

We had our best flight of the season!
1'47" to the left:
https://www.youtube.com/watch?v=SFSmUwS ... e=youtu.be

1'43" to the right:
https://www.youtube.com/watch?v=SqX2U7w ... e=youtu.be

Average is 1'45" which is where I had set my goal originally, so now I need to work more on consistency.

The climbs are still steep but we're launching at about 4500 turns/0.45 in.oz now, whereas we were launching at 4000/0.3 in.oz before today. As mentionned, it appears we need the steep climbs to get height quickly before the launch torque spins off. Also as predicted, we had to re-trim the planes from scratch.

The one I built is with the movable wings is consistently 10 seconds better so we will need to incorporate that onto Luke's plane as soon as he can manage the additional complexity. He's getting over 1'30" with some regularity, not too bad.

I won't rule out a rubber stripper (or 5/99 rubber, lol) but IMO we're not good enough yet to take full advantage or justify the investment.


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