Oct 11, 2015, 02:46 PM i can't learn fast enough Aubur, NY-- Finger Lakes Joined Mar 2009 253 Posts Help! Material Questions, and calculations Well I have been building for the last couple of years with about half success ration, some fly well others, quick dirt finders. I have several sheets of MPF bought last year, and several \$tree foam. Would like to build a slow flyer for the indoor season coming up, So the questions: Suggestion for some indoor planes with plans. Trying to remember the proper calculations for wing loading and keeping it lite. I weigh the components and then try to figure out the size of plan and am getting myself completely confused Sq Ft of wing divided by weight ='s ?? How lite should I be for a slow flyer indoors. Then if I have the component weight I need to work backwards to figure the size and weight. I really hope this rambling is somewhat clear, Thanks in advance for your time and patience and all the the great sharing of info. Terry
Oct 11, 2015, 07:31 PM
Hot glue held together by foam
United States, WA, Vancouver
Joined Aug 2010
4,507 Posts
Quote:
 Originally Posted by Terry Glenn Well I have been building for the last couple of years with about half success ration, some fly well others, quick dirt finders. I have several sheets of MPF bought last year, and several \$tree foam. Would like to build a slow flyer for the indoor season coming up, So the questions: Suggestion for some indoor planes with plans. Trying to remember the proper calculations for wing loading and keeping it lite. I weigh the components and then try to figure out the size of plan and am getting myself completely confused Sq Ft of wing divided by weight ='s ?? How lite should I be for a slow flyer indoors. Then if I have the component weight I need to work backwards to figure the size and weight. I really hope this rambling is somewhat clear, Thanks in advance for your time and patience and all the the great sharing of info. Terry
I don't worry about calculations - if I want to make a plane VERY slow flying I make the airframe as light as possible with as much wing area as possible , and then add the lightest weight electronics that will fly the plane . I don't add anything it doesn't need to fly - no landing gear , reinforcements , decorations , etc . And if all you want it to do is fly slow , an under-cambered wing ( permanent droops and flaps ) helps , and set the CG to the rear just shy of porpoising .

This is probably my slowest flying scratch-built foamy :

 Lightweight 40" wingspan FT Old Fogey-ish (2 min 58 sec)
 Oct 12, 2015, 11:09 AM treefinder SE MI Joined Oct 2004 11,056 Posts Terry: I think you are looking for wing loading: plane weight in ounces /wing area in square feet. Most of my onesheeters are in the 5-7 ounces /sq ft range and are nice slow floaty flyers if need be. If you can get a plane down to around 3 oz/sqft, you will have a real floater. Like BOC said, go for as light a build as you can and as much wing area as you can. My One Sheet Floater does just that; oversize wing and tail surfaces, and dollar store foam with minimal reinforcements.
 Oct 12, 2015, 12:10 PM i can't learn fast enough Aubur, NY-- Finger Lakes Joined Mar 2009 253 Posts Thanks Springer. What I am trying to do is go backwards. I know the weight of the mtr, esc, servos and battery. So in order to keep it lite, by working backwards I can determine the wing area needed to keep it at 3 oz. Thank way I can determine the size for indoor flying. I am having brain blank, to be able to reverse the calculation. Does any of this make sense Thanks again for all your help and insperation. Terry
 Oct 12, 2015, 12:48 PM treefinder SE MI Joined Oct 2004 11,056 Posts It'll be tough to get a perfectly accurate number, as the weight of the foam is going to be variable depending on how much area/size you decide, but if you figure for instance, the gear weighs 3oz and you add in 3oz for the airframe you are at 6oz total and 1 sqft/3oz X 6oz = 2sqft. Now 3oz/sqft is a real floater, and you can fly indoors (in a larger gym, or soccer arena, etc) at double that wing loading nice and slow. A lot depends on the plane design, as a draggy plane will naturally fly slower just due to the drag on the plane, while a sleek design may be harder to slow down. High wing undercambered airfoil, boxy fuselage, landing gear for more drag, large tail surfaces to add more area and reduce loading (even though we don't count that in the calculations) all will help slow it down.
Oct 12, 2015, 03:50 PM
Hot glue held together by foam
United States, WA, Vancouver
Joined Aug 2010
4,507 Posts
If you want to go really slow and small , you could try building a foam or carbon fiber rod skeleton airframe with film covering on the wing and tail feathers , powered by a micro all-in-one brick ( like a Night Vapor ) . Many plans , etc in the scratch-built indoor/micro forum . I've made a few planes that way using the ( free ) lightweight film from a grocery store produce bag for the wing/tail feather covering .

Spektrum compatible brick for 2S brushless motor :
http://www.targethobby.com/ar6400lbl...p-4162363.html

Flysky compatible brick :
http://www.banggood.com/WLtoys-F929-...-p-930768.html

Here is one I made flying inside a church sanctuary :

 Homemade indoor slowflyer (1 min 16 sec)