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Author Topic: adventures with living room flyers  (Read 309 times)
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vinnieg
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« on: April 28, 2022, 09:19:25 AM »

I started dabbling with Indoor Duration models a few months ago and built a few penny planes. My eventual goal is to make a LRF with a duration of 4+ minutes without banging on the ceilings. This one weighs in at 1.25 grams without motor. It's based off the Poonker plans which are scaled up by 30%. The thrust bearing is 3D printed and the props are foam. The prop is likely a little small for the model. I plan on building a bigger one as the next step.


https://youtu.be/wSHAzXY4sho

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vinnieg
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« Reply #1 on: April 28, 2022, 06:15:15 PM »

I built a 6" prop which gets me to about 1:20 seconds with 1000 turns on a 1/16th strand
https://youtu.be/CTUqhdL5Htw
« Last Edit: April 28, 2022, 06:46:14 PM by vinnieg » Logged
lincoln
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« Reply #2 on: April 28, 2022, 08:59:19 PM »

Looks like fun. Also looks like your living room has a higher ceiling and fewer obstacles than mine. I wonder if you couldn't make  a lighter prop hanger and prop. Also, thin, properly shaped balsa blades might be more efficient.
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Hermie
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« Reply #3 on: April 30, 2022, 06:47:44 AM »

I’m still learning, so I won’t make any suggestions. Just keep trying because you are close to your goal. That living room has lots of height, but those corners really trap your bird.
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vinnieg
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« Reply #4 on: April 30, 2022, 02:19:18 PM »

I wonder if you couldn't make  a lighter prop hanger and prop. Also, thin, properly shaped balsa blades might be more efficient.

Yea, the whole plane needs to be about 50% lighter  Smiley. Currently I need the prop and bearing weight to get the correct CG. I will need to reduce tail weight first and then the prop/bearing will follow. There will be a V2 for sure. The model design itself is great. I didn't have much trouble trimming it.

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vinnieg
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« Reply #5 on: April 30, 2022, 02:21:52 PM »

Hermie -  I feel like I will need to get really lucky to nail a 4+ minute flight in this living room. The flight below is with a new 7" prop which never made it back to the floor.

https://youtu.be/mQauIsmwUvE
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lincoln
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« Reply #6 on: April 30, 2022, 03:32:55 PM »

Do you back off a few turns before you launch? That's very useful under low ceilings. It's also possible a thinner or longer motor would help.
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lincoln
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« Reply #7 on: April 30, 2022, 03:48:51 PM »

More prop pitch might help, too. Or a "flaring" prop that flexes for more pitch when the torque is higher. These and the ideas in the previous post are meant to slow the climb.

BTW, in competition, it's allowable to "steer" your model with a pole or a balloon on a string, to keep the model from hitting the wall. I think the rule is that you can't change the height and the prop shouldn't stop, but it's been a while since I checked the rules. If you have a light pole, long reed, etc. steering might help. However, it requires some finesse. There's probably an article at Indoor News and Views.
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ghostler
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« Reply #8 on: April 30, 2022, 06:11:36 PM »

Nice work, a little tweaking and bet you'll have an excellent flyer.

Some 50 years ago, I remember the Comet Struct-O-Speed (I think that is what it was called) sheet balsa full fuselage stand-way-off-scale low and high wing cabin die cut and color stamped kits, 1/32nd in. thick sheet balsa, with nominal wingspans of around 6 inches (150 mm). I managed to get them to fly, was kind of novel in a way and cheap.
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lincoln
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« Reply #9 on: April 30, 2022, 10:30:21 PM »

I don't think they'd qualify as living room models unless you made them out of light foam. There's a 15 inch Struct-O-Speed Piper Cub on Outerzone. Also a Cub and a Curtiss Robin here on Hip Pocket. At parmodels.com , you came find what must be dozens of similar model designs from a bunch of other manufacturers. They have the markings as well, which you can iron on. Hmmm..I wonder if it's actually possible to get a foam one light enough to do an 8 or 10 foot circle. Anyone know how light they can make extruded foam?
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vinnieg
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« Reply #10 on: May 01, 2022, 06:44:37 AM »

I did wind to 1250 and backed off a 100 turns. But more back-off is likely needed. And yes, the prop is a flarring design but I'm not sure how much my version actually flares. I will try increasing the pitch a bit. I also want to try an 8" prop version. I've been using the Prop Picker spreadsheet to help guide me when trying  different sizes, pitches and shapes. It's an awesome tool.



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Crabby
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« Reply #11 on: May 01, 2022, 07:43:11 AM »

Awesome indeed. I was gonna use it but first I think I need to head back to Yale for some refresher courses in trig, calculus, algebra, and Greek.
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vinnieg
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« Reply #12 on: May 02, 2022, 09:54:22 AM »

Awesome indeed. I was gonna use it but first I think I need to head back to Yale for some refresher courses in trig, calculus, algebra, and Greek.

Crabby  - the spreadsheet looks intimidating but it's pretty simple once you play with it a little. All you need to do is :
  • change "T/To for cruise" to 1 (for indoor models) under the TERTIARY INPUT inputs
  • change the "Cl  wing" value to 0.6 (for indoor models) under the SECONDARY INPUT
  • fill in the remaining SECONDARY INPUT values (motor width, motor weight, model weight, wing area, prop info, etc.)
  • review  the data in the "CHECK OUTPUT" section and ensure all the cell colors are GREEN !

If you're having difficulties, post a screenshot here and I'll be happy to help out. 
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