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Author Topic: President by A.E. Hatfull  (Read 640 times)
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hp35
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« on: March 26, 2016, 03:57:00 AM »

Currently I'm building an enlarged version (125cm) of the President ( rcrevue.cz/objednejte-si/planky&planek=president[68] ) (sorry for not linking, square brackets are't recognized correctly by the editor), a model originally designed as FF by A.E. Hatfull.
As I know pendulum elevator from my F3J model only, I'm stuck in relation what the correct deflection for the elevator is. As the arm of the lever should be quite long, I do not have enough space for it, its only 35mm long. That results in a rather short servo arm. At a full servo throw of 45° only approx. 2mm of push rod throw is needed to lift the trailing edge for 5mm (this is what the drawing says I made).

So, how much deflection do I really need for flying?  Although the elevator looks nice as a pendulum, a divided elevator may be a better soluton?
Thanks for your support,
Chris
« Last Edit: March 26, 2016, 04:09:32 AM by hp35 » Logged
dosco
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« Reply #1 on: March 26, 2016, 08:40:04 AM »

It appears to be a full flying stabilizer, I'd think that 5mm deflection might be fine. Are you planning a flying stab or something else?



-Dave
President by A.E. Hatfull
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hp35
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« Reply #2 on: March 26, 2016, 10:52:57 AM »

Yes, full flying stab. I just wonder, how sensitive the elevator is with just 5mm deflection.
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dosco
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« Reply #3 on: March 29, 2016, 03:04:14 PM »

Hard to predict analytically ... I've never built one so I'm afraid I can't help.

-Dave
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Konrad
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« Reply #4 on: March 31, 2016, 02:39:01 PM »

Full flying stabs in general are more efficient than camber changing (articulated) stabs/elevators as they have less drag. But for any degree of motion they are less powerful.

As this model looks to be a Free Flight R/C assist type model, the limited motion looks to be about right. I wouldn't look for more performance (motion) as the spars in the drawing don't look to be stressed for loops or any aerobatics. If you still have concerns you can always add about 40% exponential (flatter around the stick center) to the radio's elevator response curve.

All the best,
Konrad
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Cut it twice and it's still too short!
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