Flight Times

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blue cobra
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Re: Flight Times

Postby blue cobra » March 28th, 2010, 9:11 am

illusionist wrote:does anyone have an idea as to where i can get curved wing ribs to create the aerofoil?



IMS sells them.

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Re: Flight Times

Postby illusionist » March 28th, 2010, 10:42 am

Will having an aerofoil give me a large advantage? Is it going to significantly improve the flying ability of the airplane?
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Re: Flight Times

Postby blue cobra » March 28th, 2010, 11:28 am

I believe you can fly on a flat wing, but it has to be at a high AoA, which means a lot of drag. I believe it flies similar to those light rc planes that fly basically solely on thrust from the propeller and the ailerons. Many people on here know more about the physics involved with airfoils, but I'd say you definitely want to use an airfoil to be competitive. I'm not sure what's making people think of using a flat wing, since real planes and every plan I've seen use airfoils.
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Re: Flight Times

Postby eta150 » March 28th, 2010, 12:14 pm

There was a document link posted somewhere that describes the lift given by an aerofoil, but the gist of it is that the differences in air pressure cause it to rise. Therefore, the lift is much better and the rag is lower (for the amount of lift).
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Re: Flight Times

Postby jander14indoor » March 28th, 2010, 7:44 pm

illusionist wrote:does anyone have an idea as to where i can get curved wing ribs to create the aerofoil?


Cut them yourself. Its easy once you see how.

Make a pattern (a simple arc works fine for these planes, simplex curve is nice too) from heavy poster board, mat board, illustration board, the back cardboard off a notepad. Start with a simple rectangle, say 3-4 inches wide by the longest rib you want (say 15 cm) Now, along the 15 cm edge draw a nice smooth curve (you can print out a curve from you 'puter and paste it on the cardboard). Cut along that curve as smooth as you can. Harden by soaking it with thin CA. Sand smooth.

Now, take a rectangle of balsa as long as your rib. Grain should run along the length of the rib. Cut along your pattern so that rib length edge is now curved. Slide the pattern down 1/16 to 3/64 of an inch (or per plan). Repeat cut. You now have a nice curved rib piece. Slide down again, repeat cut. Another rib. And so on.

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Re: Flight Times

Postby Draylon Fogg » March 31st, 2010, 3:03 pm

Ok just to verify, what is everyones prefered band size??
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Re: Flight Times

Postby eta150 » April 2nd, 2010, 10:40 am

For rubber bands? you have to trim your plane yourself to find out. It seems like a lot of people are flying on rubber a little above 0.090" though.
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Re: Flight Times

Postby blue cobra » April 3rd, 2010, 3:16 pm

I got my personal best time today with 2:14.50
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Re: Flight Times

Postby Chantofox » April 4th, 2010, 9:52 pm

Congratulations, mine was about 2:18
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Re: Flight Times

Postby YadoMestor » April 5th, 2010, 7:40 am

Wow, those are really nice times.
How high were the ceilings?

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Re: Flight Times

Postby blue cobra » April 5th, 2010, 9:36 am

Thank you. It was in a gym about... 23, 28 feet high? I know I could get more in a higher gym too.
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Re: Flight Times

Postby DanielleS » April 5th, 2010, 9:50 am

If anyone here is in PA, do you know the flight times that were good in each region? Thanks.

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Re: Flight Times

Postby AlphaTauri » April 5th, 2010, 12:43 pm

Lemoyne won Central with at least a 1-minute, possibly approaching 2-minute flight.
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Re: Flight Times

Postby eta150 » April 5th, 2010, 4:44 pm

BC won south with a 2:48 flight
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Re: Flight Times

Postby GitItWright » April 6th, 2010, 6:21 am

illusionist wrote:does anyone have an idea as to where i can get curved wing ribs to create the aerofoil?


[color=#0000FF]Here is another technique for making ribs. Mold them. Get a block of basswood that is at least 2" wide x 4" tall x 6" long. Lay the block on its side (4" side down) and draw a curve using a French Curve drawing template along its length, Bandsaw the block along that line. You now have two halves of a RIB SHEET MOLDING FIXTURE (RSMF).

Use either 1/20" or 1/16" balsa sheet. Cut 3 sheets to fit the width and length of the RSMF. Now, soak or slow cook the sheets (simmer) in water for about half an hour. Pull the sheets out, blot the excess water off and layer onto the bottom half of the RSMB. Press down the top half of the RSMF and clamp everything together- tight.

If you use a metal clamp, you can heat the assembly in a slow oven (200 degress) for an hour. If not, let dry for two days. When dry, unclamp the RSMF and remove the top half. Then carefully remove the 3 sheets of balsa. If really dry, they will remain curved. In fact, if you press them flat and then release them, they bounce back into their new curved state. The top and bottom sheets are the sacrificial sheets. Its the middle sheet that is important.

From here on its easy. 1) Cut a straight line to true the LEADING EDGE. 2) Mark that leading edge with a colored Sharpie marker. 3) Slice the ribs by pushing the sheet flat and cutting the length along a straightedge.
An [color=#FF0000]Master Airscrew Balsa Stripper
is a great tool for this step!

All the ribs will pop back to their curved shape and actually be tougher as their grain runs parallel to the camber of each rib. When you use them in building, try to trim them by only by cutting from the back edge which allows the curve/camber to be consistent throughout the wing or stabilizer. You can vary the camber of a rib sheet by choosing different places to make that primary, leading edge cut before slicing the ribs.

GOOD LUCK![/color][/color]
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