75g/qdm?

Recently just by coincidence I was talking to several friends about wing loading and FAI limits. It was not clear to me how is actually surface area calculated. Searching SC4_Vol_F3_Soaring_12,  SC4_Vol_ABR_12 and asking Tomas Bartovsky about help I found following:

  • 1.4 DEFINITIONS OF EXPRESSIONS USED FOR MODEL SPECIFICATIONS AND RULES

1.4.1. Surface Area
The surface area includes the total surface of the wings and that of the horizontal or oblique stabilising surface or surfaces. The surfaces taken for calculation are the orthogonal projection on to a horizontal plane of the surfaces in question with each surface at zero incidences.
When wings or stabilising surfaces are built into the fuselage of the model aircraft the surface taken into account shall include that area contained within the normal contours of the flight surfaces extended so as to meet at the plane of symmetry of the model.

  • 5.3.1.3. Characteristics of Radio Controlled Gliders F3B

a) Maximum surface area ………………………………. 150 dm2
Maximum flying mass …………………………………. 5 kg
Loading …………………………………………………….. 12 to 75 g/dm2

My understanding of above mentioned paragraphs:

  • You should calculate projected surfaces (sure, even for wing)
  • You should include tail also (sure, projected surface)
  • You should include “…area contained within the normal contours of the flight surfaces extended…” i.e. wing/tail area instead of fuselage part is also included.

Few years ago nobody was taking care about this limits. I’m afraid time is changing and as everybody who is not using Tungsten today is already looser (smile) we should know what we are talking about…

P.S. In F5B Worlds they are going to use precise planimeter (wow!)

 

2 comments to 75g/qdm?

  • sylvain

    Hi, Roman, nice to find five minutes to change my mind from current wotk.

    I agree with you that if you want to load today’s glider using Tungsten, it become important to check the mesure of the surface.
    We calculate for FOSA LIFT and the total weight (full ballast) could reach 4400g. If we calculate only with wings surface, we shouldn’t be more than 4250g.
    Si we will recalculate with stab projection (not sure we need surfaces includes “contours”).
    For sure, the risk to be upper than 75g/dm exists today !

    See you soon (in Kircheim or …)
    Regards
    Sylvain

  • Hi Sylvain,
    you are happy man if your toy is able to fly so high wing load, nearly 4500g. Hopefuly your insurance is also for high amount. See you in Kirchheim.