How to improve crappy flap geometry?
01-28-2012, 04:45 PM
#1
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How to improve crappy flap geometry?
I have sort of dug myself a hole here. I'm not sure how serious it is, but I am looking for ways to improve it. I wanted to hide all of the linkages on this ESM Raiden. On the ailerons I used that RDS system so they are fine. The flaps are iffy.
The control horn is on the leading edge of the flap as far from the hinge line as I could get and still have them hidden. Right now I have those medium red Hitec arms on them. Unfortunately the small control horn close to the hinge line means that, with the huge flaps, you can sort of overpower the servo (HS-645MG).
I can't do anything with the flap control horn. It is buried in there. In this situation will a longer servo arm make this situation better or worse?
The control horn is on the leading edge of the flap as far from the hinge line as I could get and still have them hidden. Right now I have those medium red Hitec arms on them. Unfortunately the small control horn close to the hinge line means that, with the huge flaps, you can sort of overpower the servo (HS-645MG).
I can't do anything with the flap control horn. It is buried in there. In this situation will a longer servo arm make this situation better or worse?
01-28-2012, 05:33 PM
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RE: How to improve crappy flap geometry?
A longer arm gives the servo LESS mechanical advantage on whatever is being actuated.
The short horn on the flap means higher stress on the hinges. As the rod moves closer to the pivot point, more and more of the servo's force is directed towards ripping the hinges out rather than pivoting the surface.
A torque tube on the flap with a brazed or silver soldered horn on the inside of the fuse would let you relocate the flap servo(s) into the fuselage. The torque tubes horn can be fabricated to any length you want and give huge mechanical advantage
The short horn on the flap means higher stress on the hinges. As the rod moves closer to the pivot point, more and more of the servo's force is directed towards ripping the hinges out rather than pivoting the surface.
A torque tube on the flap with a brazed or silver soldered horn on the inside of the fuse would let you relocate the flap servo(s) into the fuselage. The torque tubes horn can be fabricated to any length you want and give huge mechanical advantage
01-28-2012, 06:25 PM
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RE: How to improve crappy flap geometry?
If it were me in this situation I'd do one of two things. First move the linkage closer to the center of the servo. Doing this will require more movement of the servo to open and close the flaps. But it would have more mechanical advantage (less torque needed from the servo to move the surface) but would require more servo arm movement to achieve the same flap open travel distance. Option two would be to switch to digital servo's which tend to have more torque but also can be very pricey... The only other option is as stated by Sessholvlaru. If otion one or two are not available, Iwould work on a secondary linkage advantage in the the same bay as the flap servo.
01-28-2012, 06:26 PM
#5
RE: How to improve crappy flap geometry?
Also,
With you current set up you can also help increase holding power by having the servo not at 90 degrees like your pic shows, but closer to the 180 degree side with flap deployed, 90 degrees or where ever with flaps retracted. If the "picture" is with flaps down,, I'd shorten that rod to get the angle more to your atvantage.
good luck
With you current set up you can also help increase holding power by having the servo not at 90 degrees like your pic shows, but closer to the 180 degree side with flap deployed, 90 degrees or where ever with flaps retracted. If the "picture" is with flaps down,, I'd shorten that rod to get the angle more to your atvantage.
good luck
01-28-2012, 06:33 PM
#6
Thread Starter
RE: How to improve crappy flap geometry?
ORIGINAL: scale only 4 me
Also,
With you current set up you can also help increase holding power by having the servo not at 90 degrees like your pic shows, but closer to the 180 degree side with flap deployed, 90 degrees or where ever with flaps retracted. If the ''picture'' is with flaps down,, I'd shorten that rod to get the angle more to your atvantage.
good luck
Also,
With you current set up you can also help increase holding power by having the servo not at 90 degrees like your pic shows, but closer to the 180 degree side with flap deployed, 90 degrees or where ever with flaps retracted. If the ''picture'' is with flaps down,, I'd shorten that rod to get the angle more to your atvantage.
good luck
01-28-2012, 06:51 PM
#7
Thread Starter
RE: How to improve crappy flap geometry?
ORIGINAL: tschuy
If it were me in this situation I'd do one of two things. First move the linkage are closer to the senter of the servo. Doing this will require more movement of the servo to open and close the flaps. But it would have more mechanical advantage (less torque needed from the servo to move the surface) but would require more servo arm movement to achieve the same flap open distance. Option two would be to switch to digital servo's which tend to have more torque but also can be very pricey... the only other option is as stated by Sessholvlaru. But I would work for a secondary linkage advantage in the the same bay as the flap servo.
If it were me in this situation I'd do one of two things. First move the linkage are closer to the senter of the servo. Doing this will require more movement of the servo to open and close the flaps. But it would have more mechanical advantage (less torque needed from the servo to move the surface) but would require more servo arm movement to achieve the same flap open distance. Option two would be to switch to digital servo's which tend to have more torque but also can be very pricey... the only other option is as stated by Sessholvlaru. But I would work for a secondary linkage advantage in the the same bay as the flap servo.
01-28-2012, 08:05 PM
#8
RE: How to improve crappy flap geometry?
Lengthen the control horn on the flap. When in the extended position it will increase the distance between the linkage and hinge. This will give you better power to the surface. The revised drawing should explain the rest.
02-05-2012, 09:03 AM
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RE: How to improve crappy flap geometry?
ORIGINAL: Sessholvlaru
That's a good tip. I can go in one more hole on the servo arm and I have plenty of throw to spare. Thanks!
ORIGINAL: tschuy
If it were me in this situation I'd do one of two things. First move the linkage are closer to the senter of the servo. Doing this will require more movement of the servo to open and close the flaps. But it would have more mechanical advantage (less torque needed from the servo to move the surface) but would require more servo arm movement to achieve the same flap open distance. Option two would be to switch to digital servo's which tend to have more torque but also can be very pricey... the only other option is as stated by Sessholvlaru. But Iwould work for a secondary linkage advantage in the the same bay as the flap servo.
If it were me in this situation I'd do one of two things. First move the linkage are closer to the senter of the servo. Doing this will require more movement of the servo to open and close the flaps. But it would have more mechanical advantage (less torque needed from the servo to move the surface) but would require more servo arm movement to achieve the same flap open distance. Option two would be to switch to digital servo's which tend to have more torque but also can be very pricey... the only other option is as stated by Sessholvlaru. But Iwould work for a secondary linkage advantage in the the same bay as the flap servo.
02-05-2012, 12:35 PM
#10
Thread Starter
RE: How to improve crappy flap geometry?
ORIGINAL: tschuy
Did you get-r-done?
ORIGINAL: Sessholvlaru
That's a good tip. I can go in one more hole on the servo arm and I have plenty of throw to spare. Thanks!
ORIGINAL: tschuy
If it were me in this situation I'd do one of two things. First move the linkage are closer to the senter of the servo. Doing this will require more movement of the servo to open and close the flaps. But it would have more mechanical advantage (less torque needed from the servo to move the surface) but would require more servo arm movement to achieve the same flap open distance. Option two would be to switch to digital servo's which tend to have more torque but also can be very pricey... the only other option is as stated by Sessholvlaru. But I would work for a secondary linkage advantage in the the same bay as the flap servo.
If it were me in this situation I'd do one of two things. First move the linkage are closer to the senter of the servo. Doing this will require more movement of the servo to open and close the flaps. But it would have more mechanical advantage (less torque needed from the servo to move the surface) but would require more servo arm movement to achieve the same flap open distance. Option two would be to switch to digital servo's which tend to have more torque but also can be very pricey... the only other option is as stated by Sessholvlaru. But I would work for a secondary linkage advantage in the the same bay as the flap servo.
I moved the clevis in two holes, it seems to have helped a lot.
