Surface throws

[Alex Hasell]

Hoping someone can quickly clarify this one for me i think i have the controlsurface throws set as per my kit instructions but would very much like to hear from you all how and what you find the best and most accurate way of setting and measuring yours

Many Thanks.

Alex

[Andy Harris]

Alex

Some kits come with a measuring jig (Precision Aerobatics) and some quote as deflection in millimetres.

I guess from your post that yours says 30 degrees or similar.

On a trainer you don't have massive control surfaces, this gives rise to two things:

     a) Lots of control input is required to give an effect in flight

     b) You can't do any tight manuveurs

The layout of the surfaces and servos will mean that the throws will naturally drop out right.

To double check you can use simple maths. if the throw is 30 degs then deflection is:

   def = sin(30) x ControlSurfaceWidth 

   so for a 20mm Aileron 0.5x20 = 10mm  -- just measure with a rule. 

Here's some online tables:

http://www.industrialpress.com/en/tabid/63/default.aspx

In practice you can tell what the max throws are by the physical movement available, set full rates to be a little less than this to avoid stress, then make low rates about half of this. 

The centres are set on the push rods and the throw ratio is set by the horn hole chosen, closer to the surface the more throw you get. 

Back in March I was asking the same questions ... 

Regards

Andy 

PS remember the EXPO and apparently JR and Futaba have different numbering schemes, 

[Alex Hasell]

Thaks for the reply there Andy. Im sorry to say although that does help me understand the process a little more i am still slightyly confused. You see no my model does not come with any sort of jig at all yes it is a trainer. The throws in the manual are given not in degrees (i wish they were) but in inches which to start with really doesnt help me as i was taught metric! Although having said that your above estimate of the aileron been 20mm wide = a throw of 10mm is about right as in the manual  its given as 3/8" up 3/8" down which is roughly 10mm so that is obviously what it should be, it then states to measure this dimension at the thickest part of the control surface! as in the instance of the ailerons which are slightly tapered do i measure this 10mm as close to the hinge as poss which then gives the trailing edge a greater deflection than 10mm or measure at the tip of the aileron so the whole aileron would have a totall travel of 20mm from the max up to down deflection. I just want to be sure i have this correct before any flights so i do not have a fight on my hands before i start.

Many Thanks

Alex

[Tim Mackey]

tip of the aileron ( trailing edge )  and other control surfaces ditto.

[Andy Harris]

Alex

 This is about right. 3/8 near enough 10mm, and 20mm max deflection.

 Regards

Andy 

[Kelly]

Hi Alex,

I use a ruler held vertical to the control surface.

 

 measure at the points shown by the red arrows.

Make sure the trims are set at zero  and the control surfaces are centred  with the radio gear on ( see your instuction book that came with your radio gear).

Using the ruler as shown measure the throws and adjust the dual rates  as per your insructions for your radio.

You will find the boomer is very responsive on the training/low rates. 

Hope this makes it a bit clearer.

[Tim Mackey]

well done there kelvin

[Alex Hasell]

indeed well said Timbo that is excellent thankyou Kelvin i have gained so many usefull things from you guys which i can now pass on in my build blog . You know that has really quite suprised me that 10mm is all it takes to manover the airframe through the sky well i guess all things are proportional and as its not a 2m acrobat then 10mm is quite alot in comparison.

I thought to myself that was the logigal way of doing it but when the book says measure at thickest part of the surface i hope you can see why i had to question it!

And Kelvin i very much enjoyed your 109 build blog good stuff

Thankyou All, Alex

[Doug Ireland]

Hi Alex, next time you're on an airliner get a seat over the wing and you'll see just how little control movement is needed to put a 747 into a 60 degree bank! Its quite impressive!

[Tim Mackey]

Ah yes, but thats because the pilot / computer is synchronised with the trolley dolly leaning over the seats with bottles of wine for the boozers in the window seats !

[Alex Hasell]

[Doug Ireland]

Hmm, forgot about the c of G shift! must get slimmer Trolley Dollies!

[Tim Mackey]

yeh, and female only too

[Former Member]

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