Wright Stuff C

[nobodynobody]

We were trimming the other day and something interesting happened. I'm sorry that we don't have a video, we weren't recording at the time.

Our plane started to climb but the radius was too big. It hit (sort of grazed) the wall and instead of recovering, it dived straight down to the ground and the prop broke. Why is this?

We have a ff monoplane, with about 3-4 mm of incidence. The rudder was about 5 degrees to the left and the cg was 1.15 in forward of the trailing edge of the wing. We were using about 2g of .065" rubber at 100x15 winds.

I have no idea either lol. I had the same problems too. I have found that if my plane does the same thing. It has a hard time regaining its momentum as planes are pretty sensitive this year. Sometimes, my plane will even go a half circle in the wrong direction after hitting something. Check if the cg was pushed up because it hit the wall. Props also break a lot this year. My recommendation is to just continue testing normally and make the radius smaller.

[lechassin]

Agree to just make the radius smaller. Add some wing incidence if the extra rudder causes extra banking and results in diving. I don't think any airplane can recover from dragging a wingtip against a wall.

The small props this year are spinning fast so they'll tend to break if they hit something, and power-diving into the floor only makes that worse. The props that are included in this year's kits are nothing more than cut down larger props meant to spin slowly, and they are poorly adapted to this year's rules.

A prop with a strong hub and flexible blades will minimize the risk of breakage.

[coachchuckaahs]

I would not change anything substantial in the basic vertical trim based on one wall hit. I would tighten the circle and re-establish vertical trim as others have mentioned.

However, I would suggest "trying" for a light ceiling hit or two, and see how it recovers. Wall hits are tough. If it lightly hits a girder and does not recover, you need to increase stability and retrim.

Props MUST be robust. If you have to change props between flights, you lose the bonus.

Coach Chuck

[Lorant]

How do we select proper rubber band length?

[coachchuckaahs]

How do we select proper rubber band length?

Take careful notes, review your log.

You need to match your rubber to your prop and your plane.

Out of rubber before landing, go to thinner rubber. Too many wings left, go thicker. As far as length, that is an optimization through experimentation. All these items work together. Change one and others will have to be adjusted.

Coach Chuck

[coachchuckaahs]

All I can say is plan for the unexpected!

A few weeks ago we got notice that our Regionals had lights at 30', girders at 33. So we focused our half rubber flights at 15-16 feet.

When we entered the gym yesterday, the lights were clearly lower, around 26-27 feet. Unfortunately, we got so focused on adjusting our rubber and torque for 30, we had little recent data to work form at lower altitudes. We backed off our launch torque a bit and hoped for the best. There was also a curtain partially lowered, which prevented us from accessing the largest spot between lights.

The plane flew well, but exceeded the light height by about 6 inches. The lights are old-time fluorescent flat fixtures, hung by two wires. The plane passed over a fixture, between the wires. The next pass, it had come down a few inches, and hit on top of the light. The plane got hung. Our stick was not long enough to knock it down, so the kids had to go to the backup plane. The plane actually hung by the 0.018 metal skid under the prop, which was installed to prevent prop damage on landing. Guess that has to go!

The second plane/prop require higher torque, but had not been flown much by these two (I have 4 kids on the team). They were concerned about hitting the lights again, so reduced the torque even more (though it should have been at least 0.1 higher than plane 1), and the plane only climbed to 10 feet. Got 56 seconds out of it, but just did not use the gym well. Fortunately, it was still the winning time, but we must learn form our mistakes.

1. Know the game plan for BOTH planes. Don't assume that Plane 1 will survive! It was a written game plan, but we only reviewed plane 1 the morning of the event.
2. Have retrieval options suitable for the facility. Our stick was 20' long, and the plane was only inches out of reach. I had a damaged carbon stick in the car, which we retrieved, taped two sections to the good stick, and retrieved the plane in a few seconds. Had I thought it through, we would have had the taped-together sticks ready during the event, and would have been able to fly the plane for the reverse direction bonus.
3. Work diligently to get the two planes to perform the same. We essentially split into two pair in practice to perfect each plane, but the end results were too divergent. We need to do better in converging to a common solution.

On to State. Only 3 weeks to prepare!

Coach Chuck

[lechassin]

Thanks for sharing your experience. It confirms what we've noticed too which is that there are many many parameters to optimize beyond a good flying plane.

Congrats on making it to State (again) and good luck, I'm anxious to see what your times are near the end of the season. I don't think we will advance past regionals, but we are still enjoying maximizing the plane's performance.

[bjt4888]

Coach Chuck,

Very unfortunate that the room dimensions weren't as communicated. I'm sure your team will gain redemption at States and fly much better.

Yes, challenges this year are great. We also had "room issues" with an Invitational. Really bad blowers moving air laterally. My team that won had a lot of practice by that time and saw the issues other planes were having. They calculated how long they could be in the air before traversing the long dimension of the floor space with the blowers pushing them and determined that a 1/2 power flight was all they could do. So, they flew about 18 ft high in a 30 ft ceiling site and got up and down in each direction before hitting the obstructions that the majority of the other teams had trouble with. Not an ideal situation. My other two teams that were at this invitational each had contact with the obstructions (basketball goals) on one flight, they were lucky enough to retrieve to fly both flights though and finished second and third.

More excitement than necessary.

Brian T

[jsegal]

Can you make a freedom flight monoplane turn with just rudder or do you have to use a shim. I am having trouble understanding what a shim does can anyone inform me. Thanks for the help!

[Creationist127]

Can you make a freedom flight monoplane turn with just rudder or do you have to use a shim. I am having trouble understanding what a shim does can anyone inform me. Thanks for the help!

As far as I know, the shim works best. To use one, you put it between the wing mount and the motor stick, behind one of the wing posts, so that it warps the wing, making one side of the wing tilted higher than the other. To my knowledge, this makes one side rise more than the other in the air, making the plane turn. To change direction, put the shim under the other wing post and tilt the rudder in the other direction.