Primarily for general aviation discussion, but other aviation topics are also welcome.
User avatar
By Flintstone
FLYER Club Member  FLYER Club Member
#1300762
Given the way my last 'this-thought-just-popped-into-my-head' thread went (south!) I'm reluctant to start another but here goes.

The Fury is a 7/10 semi-scale replica built from plans. What level of embuggerance would it be to scale the plans back up to 10/10 and build from there? Obviously some materials and components would require more than a simple beefing up but is it do-able?
User avatar
By davey
#1300766
Thinking laterally, and not having a clue what sizes are involved. How about photographing the profile parts, Ribs etc. then having them scaled up on a commercial printer ?


Edit: the photos would be of the plans not the actual parts..
Last edited by davey on Wed Jul 23, 2014 12:39 pm, edited 1 time in total.
User avatar
By VRB_20kt
FLYER Club Member  FLYER Club Member
#1300769
a) Not sure that they make bolts that are 10/7 of n millimetres...

b) Some (most I suspect) forces increase as the square of size... :pale:
User avatar
By nallen
FLYER Club Member  FLYER Club Member
#1300773
What level of embuggerance...?


A lot. (Plus, any the visual tweaks that the designer made to make the 7/10 look "right" would be enlarged, so that you might end up with something looking even less like the real thing.)
By ozplane
FLYER Club Member  FLYER Club Member
#1300776
And then you would need a RR Kestrel to drag it all along.
User avatar
By Genghis the Engineer
FLYER Club Member  FLYER Club Member
#1300777
Pretty straightforward, but it wouldn't be a linear scaling and you'd have to completely re-analyse the aeroplane.

70% linear is 0.7 x 0.7 x 0.7 = 34.3% So by volume that full scale aircraft will be just under 3 times the size, and thus weight. Your main structural components then will have to be at-least 3 times as strong, which means that some components - mainspar, fuselage longerons and undercarriage particularly will need to be about 3 times the cross sectional area as well, not just 30% bigger.

So the internal shape will change a lot, and the total weight for a 30% bigger airframe by linear scale will be around 4 times as great.


Rotational intertias will change as well, which particularly will change spinning characteristics so that'll be a major area of re-testing, as will stalling characteristic due to the significant change in wing loading (wing area will only increase by about (1/(0.7*0.7) = 2, so the wing loading will about double). Other than that, handling should be pretty similar, but performance will need completely re-evaluating.

G
By golfcharlie
#1300799
When I visited the build of the French 7/10 Mossie built at Lucon some years ago, I asked about the plans. The answer: Tres simple, Monsieur. Aeromodeller Plans Service and enlarge."
It worked for them. Saw their Mossie slow roll last weekend at Vichy. The rest was a bit of a bore.
By Crash one
#1300821
Doesn't the Reynolds Number thing come into this? I don't know how it is applied but it's not possible to just "scale" linearly or it's all wrong.
User avatar
By Paul_Sengupta
FLYER Club Member  FLYER Club Member
#1300931
Marjorie wrote:v(e/a*)in


Is that the equation to use?
User avatar
By mick w
FLYER Club Member  FLYER Club Member
#1300935
Think of a 32nd scale model Balsa Aircraft , it might have 16th" square longerons ,I doubt you would build the full size one with 2" x 2" ones . :thumright:
User avatar
By Flintstone
FLYER Club Member  FLYER Club Member
#1300941
Rotorboater wrote:Scaling is what photocopiers are for :D


By George, that's it.

A photocopier, right? Linked to a 3D printer!!
By Frank Leopald
#1300949
My warped mind works the other way.

What about a double scale Turb or Cub? Everything in proportion just twice as big. You'll have to compromise with the seat and controls but imagine the sight of something that looks much nearer than it is.

FL