stunthanger.com

Building Tips and technical articles. => 1/2 A building. => Topic started by: Jeffrey Olijar on August 16, 2009, 03:12:34 PM

Title: Skyray formation
Post by: Jeffrey Olijar on August 16, 2009, 03:12:34 PM
I have had this idea for awhile now and decided to clean out my scrap box and build it.  the rear two skyrays will be the elevator and I will have the .049 mounted in the back in between the middle two in a pusher configuration.  So far the plane or rather planes weigh 2oz.  I just thought I would share my progress with everyone.  I have a few concerns mainly making it so it can pass a pull test.  Also I am not exactly sure where I want my center of gravity to be as I have never done a pusher before.  
Title: Re: Skyray formation
Post by: Robert McHam on August 16, 2009, 05:06:54 PM
I like!

Robert
Title: Re: Skyray formation
Post by: minnesotamodeler on August 17, 2009, 03:28:16 PM
Somewhere I saw a pic of a similar setup, using "Blue Angels" models or something similar, I think just 4 of them though.  Very clever, interesting look in the air.  It can work.
Title: Re: Skyray formation
Post by: Jeffrey Olijar on August 17, 2009, 05:01:45 PM
it was in model airplane news in the 70's-80's?  I remember seeing it when I was a kid (no im not that old but I did look through them when I was a kid)
Title: Re: Skyray formation
Post by: LARRY RICE on August 17, 2009, 06:05:06 PM
I AM THAT OLD,,,OLDER AND I REMEMBER IT TOO....SOMETIMES.
LARRY (HOW DO YOU MAKE THESE DAMN CAPS GO AWAY?)
Title: Re: Skyray formation
Post by: Larry Renger on August 17, 2009, 06:50:07 PM
Treat each model as the sum of its total area and note its position, counting the midpoint of the wing chord as the location of that bit of area.  Figure out the center of all the areas (a good guess will do).  Measure the frontmost to rearmost area centers, and put the cg 10% of that distance ahead of the center.  That should be a safe CG.  I am sure you will find that you need the engine as a tractor on the front plane to achieve this.

As a final test, tie a string to the model at that point, if needed, steady it with a stick from one of the wings (rubber band everything together) and swing the thing around in the air.  If it flies smoothly it is OK to fly, if it hunts or, worse, flops around, you need the CG farther forward.

I have successfully trimmed a variety of flying wings, including forward swept ones this way.  Never a bit of damage on the first flights!  And I do have a free-flight .010 formation of 4 Guillows gliders that flies just fine.  The engine is on the front model, and ff models tend to balance more aft than c/l.
Title: Re: Skyray formation
Post by: Bill Heher on August 18, 2009, 11:28:56 PM
  Here is a link to the Flying Lines site- with a picture of a diamond 4 formation flight. I think this set-up had a throttled .10-.15 on it.  Bill Darkow flew it- he might have some advice for you, he likes the unusual and different.

http://flyinglines.org/chehalisairfair.09.html