Wright Stuff C

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Re: Wright Stuff C

Post by CrayolaCrayon »

lechassin wrote: October 23rd, 2019, 7:19 pm We went to the well-lit parking lot near our house with one of the first planes I made, very little breeze, and torqued the 0.008" thick prop to 0.3 in.oz, our usual launch torque.

The prop works, um, great...

...the plane climbed above the lights (25-30 feet) and just plain disappeared into the night sky. It surely came down somewhere but I absolutely cannot find it.

Soooo, that's two planes that have flown away outside testing improved props, without intentionally over-torquing the launches. We're down to the plane Luke made and the plane I made with the shifting wings, so in addition to me making another 0.008" thick prop, now's a good a time for Luke to make himself another plane.

Note to self: stop over-doing it outside :oops:

Range finders are helpful! If you're able to get one, you can spot your plane in the sky if you fly in somewhat visible light.

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Re: Wright Stuff C

Post by lechassin »

I was able to try again outdoors today and the 0.008" prop spins much faster at launch than the rigid prop, so I think the blades are stalling from excessive pitch. Even launching at 4110 turns and 0.4 in.oz torque, the plane behaves fine but the flight is a blah 1'07" with 1/2 row remaining. At least we know not to bother with thinner material.

So the 0.010" thick blades seem to be best for us at this time, maybe we'll try 0.009".
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Re: Wright Stuff C

Post by lechassin »

We made a video of a flaring prop build in case anyone else wants to take advantage of the increased surface area intrinsic to a three-bladed design:

https://www.youtube.com/watch?v=vmB4-4I ... e=youtu.be

The new blades are from lower down on the same single serving Pepsi bottle that provided our 0.010" blades, but they're 0.012". Apparently where the blades are cut from a bottle matters. The video is longer than I thought it would be but it is detailed enough to be useful. The sound isn't strong but with earphones is easily understood.
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Re: Wright Stuff C

Post by lechassin »

All our motors today seemed weak. I hope I just over-stretched them during break-in because they all did the same thing today: two runs using 4200 turns to reach to 0.6 in.oz torque, breakage on the 3rd run, power during the flight seemed anemic, many turns remaining, no airframe changes. This is how our motors usually behave just before breaking (5-10 flights). Launches at 0.3 in.oz torque and 4000-ish turns.

In spite of that we got consistently around 1'30" all day both ways with both planes. The flaring props work well and we note a consistent need to have less decalage going to the right to reduce erratic climbs.

Luke's plane with 0.012" prop blades and a 1mm shim we remove from the under the wing's leading edge when going right (climb still erratic):
https://www.youtube.com/watch?v=gIZRCyU ... e=youtu.be
1'33" right and 1'32" left.

My plane with 0.010" prop blades and shifting offset wings, 1mm less decalage to the right. The thing to note is that climbing to the right is much cleaner:
https://www.youtube.com/watch?v=5ewFOZ8 ... e=youtu.be
1'30" to the right and 1'31" to the left.

My plane did match its best 1'44" once with a motor left over from last week. Hopefully this is where we're at with good motors made up for next week, with shifting offset wings and 0.010" blades installed on Luke's plane.

Luke also needs to make his back-up plane.
Last edited by lechassin on October 28th, 2019, 4:42 am, edited 1 time in total.
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Re: Wright Stuff C

Post by DatSciolyBoi »

My airplane just refuses to climb, no matter how much we change the decalage, But whenever we raise the front post to provide more lift, we need to compensate with ballast at the front so it won't stall. How can we get the plane to start climbing?
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Re: Wright Stuff C

Post by xiangyu »

DatSciolyBoi wrote: October 27th, 2019, 4:42 pm My airplane just refuses to climb, no matter how much we change the decalage, But whenever we raise the front post to provide more lift, we need to compensate with ballast at the front so it won't stall. How can we get the plane to start climbing?
Did you build your own plane or did you build from a kit? Try moving wing back a bit, our wing is almost at the center of the plane (this year is a little different than last year where we were able to put wing right up in front).

Otherwise, provide more details/a picture and I can try to help you more.

Also, I'm sure that many others on this forum who are more experienced than me can be a better help.

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Re: Wright Stuff C

Post by xiangyu »

lechassin wrote: October 27th, 2019, 2:09 pm All our motors today seemed weak. I hope I just over-stretched them during break-in because they all did the same thing today: two runs using 4200 turns to reach to 0.6 in.oz torque, breakage on the 3rd run, power during the flight seemed anemic, many turns remaining, no airframe changes. This is how our motors usually behave just before breaking (5-10 flights). Launches at 0.3 in.oz torque and 4000-ish turns.

In spite of that we got consistently around 1'30" all day both ways with both planes. The flaring props work well and we note a consistent need to have less decalage going to the right to reduce erratic climbs.

Luke's plane with 0.012" prop blades and a 1mm shim we remove from the under the wing's leading edge when going right (climb still erratic):
https://www.youtube.com/watch?v=vmB4-4I ... e=youtu.be
1'33" right and 1'32" left.

My plane with 0.010" prop blades and shifting offset wings, 1mm less decalage to the right. The thing to note is that climbing to the right is much cleaner:
https://www.youtube.com/watch?v=5ewFOZ8 ... e=youtu.be
1'30" to the right and 1'31" to the left.

My plane did match its best 1'44" once with a motor left over from last week. Hopefully this is where we're at with good motors made up for next week, with shifting offset wings and 0.010" blades installed on Luke's plane.

Luke also needs to make his back-up plane.
Interesting. Just a note maybe it's just me but I don't think your first youtube link is working.

Updates on my progress today in the gym.

After fixing the plane, we tried some different things with the rubber length and is able to increase our flight time consistantly by 10 s up to around 1 minute 18 seconds both ways. I built a "flare prop" out of some Ikara propellers but it didn't appear to work. Lechassin, your new video on how to build flare propellers will probably be my guide to build another flare prop (since I built the previous one before you posted), and I'm fairly confident I can get it right (some what), so thanks for the video!

I'll keep you updated on our progress! If you don't mind me asking, what size rubber do you use? (I'll understand if you want to keep this secret :D )

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Re: Wright Stuff C

Post by DatSciolyBoi »

Testing my plane right now (tryouts are tomorrow) :( , whenever we launch our plane, it dives all the way to the left, the rudder is pointed so that it should be turning right, like all the way. But the plane still goes left, another problem is that whnever the plane runs out of winds, it glides straight forward, without turning. How can we fix the rudder?
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Re: Wright Stuff C

Post by xiangyu »

DatSciolyBoi wrote: October 27th, 2019, 7:30 pm Testing my plane right now (tryouts are tomorrow) :( , whenever we launch our plane, it dives all the way to the left, the rudder is pointed so that it should be turning right, like all the way. But the plane still goes left, another problem is that whnever the plane runs out of winds, it glides straight forward, without turning. How can we fix the rudder?
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Re: Wright Stuff C

Post by lechassin »

Xiangyu,

I think I fixed the incorrect video link. Our motors start with a 66+ inch 2.8g strand of 1/16" FAI rubber. We end up with a 32"-ish motor that stretches to 33+.

Take that with a grain of salt: rubber management is what we're weakest at. Our flight times are inconsistent which suggests we're inconsistent. A few of our flights are close to 1'45" but most are around 1'30". I don't know why there's such a range, but I think it's little errors adding up. I bet an expert would be able to point them out, but we cannot. Sometimes we run out of knots and other times there's almost a full row left, same plane and settings :? .

Luke reliably hits the 1'30" mark, so 1'45" is more of a long term hope/goal, after which I don't think there's much more to be had with our approach. It bothers me that we do best by getting to the ceiling quickly, not much more than one lap, followed by a short cruise of only a few laps, then a long/accelerating descent. We would prefer the climb, the cruise, and the descent to be more evenly divided.

I'm amazed that your monoplane with double the wing loading is already at 1'18"!
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