Wright Stuff C

[CrayolaCrayon]

Then later we saw a SO 2019 plane flying 4'25"!

[lechassin]

I see your avatar and your sig

Since you flew almost twice as long the "good" flyers last year, I'm not ruling out that this year you will fly between 2 1/2 and 3 minutes

[CrayolaCrayon]

I see your avatar and your sig

Since you flew almost twice as long the "good" flyers last year, I'm not ruling out that this year you will fly between 2 1/2 and 3 minutes

Chuck's kids and I have a late start. We've been doing F1D for the past 4 months

[coachchuckaahs]

A big change this year will be that we cannot go for a "safe" flight and then go for broke. Both flights will count under the bonus system. That may change things. As Andrew notes, we have not started yet (though we have discussed design options), and have a lot to do in upcoming months. Our Regions are in January, so time to get to work! Between State and Nationals, if we make it that far, we will have a time out for Worlds, as well as Eager AZ competition (AMA). I have no idea how we will get it all done.

As in other years, first step is a decent flying plane. You have that now. The rest of your time will be spent optimizing trim (sounds like good progress), and then optimizing rubber and prop. Keep a detailed log, look for trends, and optimize. We usually attain 300-400 flights or more, and regularly review the logs. The fact that you are in the gym already is a huge advantage.

If something is clearly indicated to be deficient in the plane design, you may need a new plane or components. But generally, if hte plane is well constructed, it comes down to trim, rubber, and props.

Coach Chuck

[lechassin]

I hope our design ideas are good and that we don't need to start over. Hearing/seeing that others have similar potential with monoplanes, two-bladed props, etc... does make me wonder.

But at the very least, our plane isn't disgraceful

[xiangyu]

I hope our design ideas are good and that we don't need to start over. Hearing/seeing that others have similar potential with monoplanes, two-bladed props, etc... does make me wonder.

But at the very least, our plane isn't disgraceful

I think bi-plane and mono-planes each have their advantages and disadvantages. As coach Chuck said, the most important part is testing the plane. As long as the plane is decently flying (I think yours looks great), then it's probably fine. So I suggest continuing using the plane you have since it works great and focus on playing around with rubber width, propeller, and other minor tweaks. At the same time you could try out the monoplane designs but I wouldn't focus too much on it.

Xiangyu

[lechassin]

Interesting day today:

We tried a rigid prop with large surface area akin to a box fan and found no time advantage. The draggy prop took high launch torque nicely (0.6 in.oz to get to the ceiling) but that was offset by high number of remaining knots, until we had reduced the pitch and cut the prop down so much it looked like our others. The next step for us is to find a plastic bottle with thin enough material to make a flaring prop.

We used the plane with wings offset to either side for CW/CCW flight and the efficiency is noticeable higher. The fixed wing version gets to the ceiling on 0.3 in.oz torque, and this plane hits the rafters once, sometimes twice at 0.25 in.oz torque. 0.2 in.oz was good but we sacrificed too many of the initial turns, so the day was a wash with times still around 1'25" both ways. We still have a ton of this rubber, so hopefully a flaring prop will help.

The offset wings have 1mm less incidence going to the right which reduces the erratic climb behavior, although the landings are a bit nose down. I suspect a motor stick with controlled bending might be optimal, especially going to the right, but again, I hope a flaring prop helps.

[lechassin]

The gym was open later today so I went back with a flaring prop made from a single-serving Pepsi bottle (0.010" thick).

1"44" to the left and 1'39" to the right.

That's a 10% increase! Never less than 1'35", say on a too-conservative launch torque. Launch torque +/- 0.3 in.oz, around +/- 3900 turns.

Everything else is the same, even the prop is identical except for thinner plastic.

Flaring works for sure.

[xiangyu]

The gym was open later today so I went back with a flaring prop made from a single-serving Pepsi bottle (0.010" thick).

1"44" to the left and 1'39" to the right.

That's a 10% increase! Never less than 1'35", say on a too-conservative launch torque. Launch torque +/- 0.3 in.oz, around +/- 3900 turns.

Everything else is the same, even the prop is identical except for thinner plastic.

Flaring works for sure.

How exactly do you make a flaring propeller? I've tried to look through the forums but still couldn't find detailed instructions on how to make them. If you can tell me some steps I would greatly appreciate it!

We went back to the gym today, we were able to get up to around 1:15 but not much further than that. Our plane seems to have random stall problems where the plane suddenly starts to slow down and then drop like 5 feet vertically. I'm suspecting it might be bacause CG is not forward enough, we didn't quite get to test my theory though since there was drift in the room (Fan on) and my plane smacked into a wall on like our third flight so RIP the wing. Nothing I couldn't fix though, but a delay nevertheless.

Congrats on the high times.
Xiangyu

[bjt4888]

Xiangyu,

See reply #125 and after here for flaring prop ideas:

https://www.hippocketaeronautics.com/hp ... =23474.125

Also, instead of creating twisting flexibility in the prop spar, you can us a flexible material for the prop blade to cause flaring. Orienting the blade so that most or all of the blade area is forward of the spar is typical. You can use a number of different materials for the propeller spar; carbon rod, basswood, hard balsa, etc. I would suggest copying a successful style and building the prop and try it. Then test as many variations and as many rubber motor densities as you have time for.

Brian T