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Author Topic: A Midair with my pennyplane...  (Read 2522 times)
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rick121x
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« on: May 23, 2012, 11:07:25 PM »

http://www.youtube.com/watch?v=RT-iy8tjmoU&feature=channel&list=UL This was at Miribelli Recreation Center in Las Vegas, where we are privileged to fly on Tuesday mornings.

The first 15 seconds of this video - in the left hand side, and definitely watch this on full screen: An flyzone electric meets up with my pennyplane. You would expect nothing but scraps of balsa knotted together with mylar flim to be remaining- well, I did anyway. But within seconds you will hear the laughing begin as the pennyplane miraculously continues it's flight, and the electric hits the floor.

A lot us us were amazed! A little glue on a moderately loosened joint, and it was good as new!

Richard
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Olbill
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« Reply #1 on: May 23, 2012, 11:59:43 PM »

This was the correct outcome!
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rick121x
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« Reply #2 on: November 19, 2013, 01:55:48 AM »

Last Tuesday, I received retribution for my plane's part in the collision of the above video. At the end of the morning's flying time, my planes were all lined up on the bench awaiting to be packed in their boxes. One fellow, still flying his electric Flyzone "something or other", clipped the wall and the plane fell onto the bench, exactly on top of my favorite indoor flyer, yes, the one in the above video. It was completely mashed, including the propeller. Wow, there was a whole gymnasium, and it had to hit exactly on that spot....

It is nearly a week, and I am still mourning.
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rick121x
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« Reply #3 on: November 19, 2013, 10:46:18 AM »

...a video of one of the early flights of this plane... in memorial.

http://www.youtube.com/watch?v=Vkekny2Yd0Y&list=ULZm9e01bZ8W8
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Bulldogger
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« Reply #4 on: November 20, 2013, 08:26:27 AM »

Sorry to hear about the fatal accident.  She was a very graceful flyer, calming to watch.  Thanks. 

How do you get the propeller to turn so slow, is it just a function of the long length and small rubber, or is it geared?

Bulldogger
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rick121x
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« Reply #5 on: November 24, 2013, 12:03:28 AM »

The slow prop speed is a function of the diameter and pitch of the prop together with the rubber thickness and winding torque. ... lots of variables, all taking testing, time,  and experience to operate reasonably.

There are reams of internet information on indoor propellers! It is an arcane art/science, and interesting that only a relatively few model builders seem to understand these variables and build record setting models year after year. True artists... and genius builders!
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lincoln
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« Reply #6 on: November 24, 2013, 07:28:53 PM »

I think a lot of RC flyers are aware only of the immediate area around their plane and don't look ahead very much. It requires a fair amount of situational awareness to fly indoors without hitting things, and many RC flyers don't have it. I like to think that I do, but it's a relative thing. I have an indoor flyer I built which is so slow that the only fun thing is to dodge obstacles. Under the swing set, over the barbecue (in use, not too low!), around that little tree, etc.  It's kind of like a big Vapor made of balsa.
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lincoln
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« Reply #7 on: November 24, 2013, 07:38:06 PM »

Bulldogger,
If you like this kind of flying, it's really not hard to build a successful pennyplane. I did my first good one in two days. I used the No Non Cents article from the following URL:
http://www.rcgroups.com/forums/showpost.php?p=11402495&postcount=62
I may also have referred to the Cezar Banks design linked to in the same post. I'm not sure. BTW, if getting Ultrafilm or something is a pain, I think that the bags that supermarkets have on a roll for putting produce in are probably light enough to use as covering. They are much lighter than Japanese tissue. Not all supermarkets use the same weight. Maybe open up and drop and pick the one that drops the slowest.

I once helped a first time Pennyplane builder get 5 minutes under a 35 foot ceiling.
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rick121x
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« Reply #8 on: November 25, 2013, 03:31:11 PM »

Re produce bags to cover indoor rubber duration models... did that. And I found that it was not really very light. I found that the local newpaper was delivered on rainy days (Not that often in Las Vegas!) with double bags - which were much thinner than the produce bags, and much lighter. These made great covering while I was learning the basics.

Now I am using the heavier covering from Ray Harlan.  http://www.indoorspecialties.com/  Nice stuff! I have not tried the thinner material that he supplies. My models are not so advanced that the lighter weight covering would make significant difference.

Good luck on flying indoor. I find the satisfaction like no other in modelling.
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lincoln
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« Reply #9 on: November 25, 2013, 07:14:25 PM »

It's true that some produce bags are too heavy. But, at least at one time, some were very light. A fraction of Japanese tissue's weight, even before doping. There was a kind that was slightly foggy and a bit crinkly that I found the lightest, but that was some years ago.

It might be necessary to shop around. I just checked two produce bags we had lying around. They are about 7 grams per square meter, which is maybe twice what I remembered. That works out to something like 0.0007" or 0.02mm. You can buy very thin trash bags in that thickness, but I've seen lighter produce bags.*

Ray's light film is very susceptible to static, but it's sort of beautiful, because it's thin enough to have color bands.

Anyone using either kind of Ray's film for the first time should be very careful about starting rips in it. On the model, it's plenty strong, but if you get a tear going, it's hard to stop. Some people use a surgical cautery or other hot tool to melt it instead of cutting it. I imagine a soldering iron with a temperature control might be a good tool. It's wonderful stuff.

*Just for yucks, I came up with a way to measure, very approximately, the weight using just a stopwatch. I arranged a bag flat, and a bit convex toward the bottom. This gave it a stable "glide" with maybe a 1:4 glide ratio. I figured that was close enough to straight down and that the drag coefficient was around 1. If you work out the math, and you're close to a standard atmosphere, the loading in ounces per square foot is around (v/7.3)^2. In this case, the bag would drop about 6 feet in around 4 seconds. (Don't just count out the seconds. Doing that, I was off by a factor of around 2!) That gives us 1.5 feet per second, or a loading of .042 oz/ft^2. Divide by two because there are two layers, and you have .021 oz/ft^2.     Times 28.3 grams and 3.28^2 (3.28 feet in a meter) and you get 6.4 grams. Pretty close, isn't it? But don't trust this method to be really close, and only try it in still air.
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TheOtherLeft
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« Reply #10 on: November 30, 2013, 06:59:37 AM »

Some measurements I took about 6 weeks ago to compare with 5 micron Mylar @ 6.8g/m2
Woolworths brand cling wrap 10g/m2
the thin plastic bags you use to bag loose bread rolls, fruit and vegies in at Woolworths etc 9g/m2, less stretchy than cling wrap, more stretchy than mylar and a lot cheaper
the bag my frankfurters came in from the Woolworths deli, bag weighed 1.6g which measures out to 4.2g/m2... thats lighter than 5 micron Mylar. You may not want to recycle if you have a cat or dog
last time I got the bread rolls they had the 4.2g/m2 bags so it can vary quite a lot
Woolworths is a local supermarket
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