Scioly.org

Welcome to Wright Stuff!

The Nationals Free Flight Society (NFFS) now sponsors the flying events, and we are striving to be an ongoing resource center for flying excellence. We have just updated our Science Olympiad Website, including a resource links page. As new resources are developed, we will keep adding to these pages. You can find them at https://freeflight.org/join-learn-fly/science-olympiad/

If you have questions on building, trimming, etc., this forum is the best place to ask. Coach Brian, Coach Jeff, and I frequent this forum and answer pretty quickly. Asking and answering here ensure the responses benefit everybody in the flying community. In addition, digging thought the prior years' forums, posted by Bernard above, is a hugely valuable resource.

Good luck, and get building!
Coach Chuck

Hello! It’s gonna take me a second to get back into the swing of wright stuff but just a general question….
Around how long should the rotor rubber band be cut in relation to the distance between propeller and back hook?

Thanks,
Scioly2345

It really has little to do with the hook-to-hook distance, other than you want the rubber no longer than 2x the hook-to-hook, and probably no shorter than 1x.

It really has to do with the width of rubber needed to sustain flight, given your propeller and airplane characteristics. This year rubber motor mass is limited to 1.5g, so the wider the rubber, the shorter the loop (you want to be right at 1.5g). I suspect you will be in the 0.05g/in range for linear density (width), give or take 25%, depending on your prop pitch and the drag on your plane. This will give you a loop length in the range of 10-18 inches. This is a VERY wide range, which will be narrowed through experimentation.

Coach Chuck

coachchuckaahs wrote: ↑September 11th, 2021, 1:18 pm It really has little to do with the hook-to-hook distance, other than you want the rubber no longer than 2x the hook-to-hook, and probably no shorter than 1x.

It really has to do with the width of rubber needed to sustain flight, given your propeller and airplane characteristics. This year rubber motor mass is limited to 1.5g, so the wider the rubber, the shorter the loop (you want to be right at 1.5g). I suspect you will be in the 0.05g/in range for linear density (width), give or take 25%, depending on your prop pitch and the drag on your plane. This will give you a loop length in the range of 10-18 inches. This is a VERY wide range, which will be narrowed through experimentation.

Coach Chuck

well said coach chuck
its uh been like two years for me so yeah i get the whole swinging back into it thing but you got this!

One area I see students struggle with is bending wire to shapes, especially prop shafts. Our team uses the "Reverse S hook" design, which does a great job keeping the rubber centered with hard o-rings. This is a tough one to bend, but I have tons of wire and keep cutting pieces until they get it right.

Now Indoor Free Flight Supply has come out with pre-bent reverse s-hooks for $3 for 10 of them. I can't bend them for that. These are in 0.020", which is perfect for SO.

To use with Ikara props, cut out the supplied wire, measure length, insert new S-hook, bend at 90 degrees (sharp), and trim off. We also glue them into the prop, rather than allowing to freewheel.

These will fit the aluminum prop hangers supplied with a number of the available kits.

While the supplied hook certainly works, the reverse-S excels as your rubber motor gets longer than the hook-to-hook distance. A normal diamond or simple loop hook can cause the hard rubber o-ring to wrap up and start hitting the motor stick.

We also like to use hard nylon for our O-rings with this. The black rubber ones are fine, but a hard nylon will stay centered and not wrap around. We use Dubro 511 antenna housing, about $2 from local hobby stores for 3 feet. Slice about 1mm wide with a sharp razor blade.

Coach Chuck

Hi,

Just want to see if it is we just got smart and patient kids or the Freedom Flight really did an excellent job for the design this time.

3 planes build by 3 pairs of students ALL fly pretty good the first time to try (~40 seconds), without any adjustment, or advices from me. Normally, I am happy if the first fly got more than 10 seconds.

Out of 3, the best one is built by 2 first time students, no flying experience.

We did get very good placement in past a few years flying events, but that was results of so many gym time flying, playing with prop pitch and rubber thickness. This year, they built and it just flys.

Tiger

FFM is known for quality designs and very good instructions. In addition, this year's rules make a very flyable plane.

WS is not so much a build event but a flight optimization event. So, congrats on a successful build and first flights. Now the actual work begins. keep a careful and complete log, and try to change one thing at a time.

Good luck, fly a lot, and ask questions if you get stuck.

Coach Chuck

Thanks Coach Chuck. Cannot agree more.

Where could I find some 1.4 to 5 micron mylar that's a wider roll than 12.4-12.6 inches?