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I want to build a AT-6 and need help with FLAPS

cdfigueredo

Well-known member
#1
Hello, everybody.
I am interested in building an AT-6 Texan but I have a question about the flaps of the model.

This model has three split flaps, which are operated by a single servo in the central section of the wing.
2J7A6891.jpg

The flaps are joined by some mechanism that transmits the movement from the central section to the flaps on both sides. I've tried to find this mechanism but it didn't work. I have few servos so i want to make it simple, just like this model.
2J7A6809.jpg
Can someone explain me better how it works?
A diagram or a picture?
Thank you in advance
 

Kendalf

Well-known member
#2
My understanding is that your picture shows a top-down view of the inside of the wing. The servo rotates to the right when flaps are activated, thus pushing the control horn on the right side down, causing the split flaps panel on the underside of the wing to rotate down. I can't find any animation or video that illustrates this, however.
 

Paracodespoder

Well-known member
#3
My understanding is that your picture shows a top-down view of the inside of the wing. The servo rotates to the right when flaps are activated, thus pushing the control horn on the right side down, causing the split flaps panel on the underside of the wing to rotate down. I can't find any animation or video that illustrates this, however.
I think he wants the mechanism of how the separate splits are hooked together?
 

Paracodespoder

Well-known member
#7
You might not need flaps, my ft mustang and mig 3 both flew really slow without flaps (similar size). If you do flaps you could just use 2 servos and do separate flaps on each side without the middle flap.
 

Hai-Lee

Old and Bold RC PILOT
#8
On smaller planes with split flaps you can use "Fingers" at both ends of the Driven flap which lock onto the top and bottom surface of the outer flaps. When the flaps are deployed the central flap moves down and the fingers on each end of the flap push the outer flaps down also. When retracting the central flap rises and the other fingers on the outer ends of the flap push the outer flaps upwards as well.

For Larger and heavier planes the flaps can be driven by a central servo IF the central servo drives a rod/axle in front of the flaps. All of the flaps have a separate connection to the rod/axle. When the flaps are moved the Servo causes the rod/axle to rotate. This rotation causes the flaps to also move due to their mechanical linkages to the rod.

For even large it is advisable to use individual servos for each surface or pair of surfaces.

I hope that gives you a few options!

have fun!
 

cdfigueredo

Well-known member
#10
You might not need flaps, my ft mustang and mig 3 both flew really slow without flaps (similar size). If you do flaps you could just use 2 servos and do separate flaps on each side without the middle flap.
I know flaps are not needed. ;). Just want to make it more scale look. Want to use a single servo because i cant order online and like to save all servos i can. And also try it... it works for they... so i want to try it.
 

cdfigueredo

Well-known member
#11
On smaller planes with split flaps you can use "Fingers" at both ends of the Driven flap which lock onto the top and bottom surface of the outer flaps. When the flaps are deployed the central flap moves down and the fingers on each end of the flap push the outer flaps down also. When retracting the central flap rises and the other fingers on the outer ends of the flap push the outer flaps upwards as well.

For Larger and heavier planes the flaps can be driven by a central servo IF the central servo drives a rod/axle in front of the flaps. All of the flaps have a separate connection to the rod/axle. When the flaps are moved the Servo causes the rod/axle to rotate. This rotation causes the flaps to also move due to their mechanical linkages to the rod.

For even large it is advisable to use individual servos for each surface or pair of surfaces.

I hope that gives you a few options!

have fun!
thanks very much... looks more clear for me.. that was exactly what i was thinking. they use a kind of "Finger" to conect the ends of the flaps to the main section. But still stuck about how to reproduce the mechanism... could you make me a kind of diagram... thanks in advance.
 

rockyboy

Skill Collector
Mentor
#13
thanks very much... looks more clear for me.. that was exactly what i was thinking. they use a kind of "Finger" to conect the ends of the flaps to the main section. But still stuck about how to reproduce the mechanism... could you make me a kind of diagram... thanks in advance.
The picture that jumped into my head for this was to glue a slightly bent paperclip into the end of the flap that is connected to the servo, and just poke it into the other flap without any glue.
 

cdfigueredo

Well-known member
#14
The picture that jumped into my head for this was to glue a slightly bent paperclip into the end of the flap that is connected to the servo, and just poke it into the other flap without any glue.
This is my idea... is that what u mean?
i think this is the way they used on the kit, but think the side flaps could bend in the opposit end...
what do u think? Sin nombre.png
 

cdfigueredo

Well-known member
#16
Yep - I think that's what Hai-Lee was describing. Or at least that's what my brain did to his description :D
:D same for me.
still worried about bend the flaps... wind presure could bend it easily i thinks. they use plastic for flaps insted EPP. i think it could help to keep the shape without bend.
Any other solution to this last problem?
 
#17
The flaps wont move if you have them connected like that. If you connect the flaps they essentially become one large flap but it will try to rotate on three different axis at different angles. When the middle and side flaps go down the space in between them will enlarge, with that piece in between them fixed it won't want to do that.
 

rockyboy

Skill Collector
Mentor
#18
:D same for me.
still worried about bend the flaps... wind presure could bend it easily i thinks. they use plastic for flaps insted EPP. i think it could help to keep the shape without bend.
Any other solution to this last problem?
Good point - EPP is pretty bend when thin. Could try laminating it with simple paper and white PVA school glue.

The flaps wont move if you have them connected like that. If you connect the flaps they essentially become one large flap but it will try to rotate on three different axis at different angles. When the middle and side flaps go down the space in between them will enlarge, with that piece in between them fixed it won't want to do that.
The secret to making it work is NOT gluing the wire into the side flap - it slides in and out of the hole while moving up and down. I've seen this kind of setup used for the linkage in fowler flaps before, but it should work just fine for this application too.
 

cdfigueredo

Well-known member
#19
Good point - EPP is pretty bend when thin. Could try laminating it with simple paper and white PVA school glue.
Do you think a paper layer could work as reinforcement for EPP? i was thinking to do it with a piece of plastic due to split flaps are really thin.
Also thinking to replace the paper clip wire for a rect plastic sheat, like this one in this corsair... (not the case, this corsair's flaps are controled by diferent servos. just for guide).
Gess that a rect plastic sheat will give it more streng and transmit more force than a single wire....
opinions???
 

rockyboy

Skill Collector
Mentor
#20
I've seen other people cover EPP with paper so they can get a nice smooth painted surface, and it does add a good bit of strength depending on the type of paper (and glue) you use. Probably need some experimentation with local materials to see what works best for what you have.

A plastic sheet for the connector like you show will probably work a lot better over time - a thin wire could start to cut through the EPP over time. And doing the whole split flap out of plastic would probably work great too - just need a little bit of framing inside to give it the right shape and let the plastic connector slide in and out.