Pike Precision - Baudis RDS - Page 4 - RC Groups
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Feb 03, 2013, 08:25 AM
F3B and F3K
RetoF3X's Avatar

Optimal RDS design

Designing an optimal RDS linkage (first order approximation):

Say your servo has +-50 degree maximum throw. Test how much subtrim your transmitter can give you. In my example 75%. This gives you 50deg +0.75*50=87.5 deg of servo throw for the downward flap deployment. Use this value for the calculation (use the common spreadsheet or do it yourself, simple geometry) of the wiper angle and the servo angle, not the 50 deg that would result if you would use not servo offset.

When you install the RDS, the flap surface is flush when you apply the 75% servo subtrim, at neutral servo trim, the flap must already be deployed.

Last edited by RetoF3X; Feb 04, 2013 at 06:56 AM. Reason: temper management
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Feb 03, 2013, 02:16 PM
Team USA F3F Member
ttraver's Avatar
Hey Reto!

Yes, I forgot to mention that part, but since it is totally different for each radio on how to do that, I just made the blanket statement that you need to zero everything, and then make your radio give it maximum throws...

I had already had the flap offset stuff going in my transmitter for the flaps...

On another note, depending on your radio, you not only can use the sub-trim to get your servo in the right place, but you can actually use camber presets as well if you run out of sub trim.

In my radio, I have the ability to set camber presets in all of my modes, so I can supplement the sub trim to get the flap back to center, but still allow the full range of motion...

Feb 03, 2013, 09:12 PM
F3B and F3K
RetoF3X's Avatar
Hey Tim

Good to know that you did over the camber presets. Yes, it is possible on some radio to completely bias all throw in one direction using subtrim and camber preset. So if you don't need much up movement of the flap, you can have all throw to deflect the flaps down.

So let's summarize it like that, conventional and RDS, when you have 0 subtrim and 0 camber preset, the flaps should be pre-deployed and you bring them with trim or camber mix to their intended position.

Last edited by RetoF3X; Feb 04, 2013 at 06:57 AM.
Feb 08, 2013, 12:47 AM
Team USA F3F Member
ttraver's Avatar
Originally Posted by Yablonsky
Nicely done Tim....I'm going to be going through everything I've done so far and taking new pictures. The GoPro doesn't seem to handle up-close pics very well, so I'll be using my iPhone, for ease of use...and the quality isn't so bad.

Looks like you're right where I am so far. I'm heading up to Bakersfield to visit my brother so I can't really do much for this thread until I get back, but then I'll be ready to move forward.

You're only down in Carlsbad...Perhaps I can drive down and check out the install in person or we can meet up or you could drive up and assist?

Anyways, I'll be updating the photos soon.

Hey Ken!

Have you started your build yet? Do you have any questions?

Hope its going good!

Feb 08, 2013, 02:10 AM
Registered User
Yablonsky's Avatar
Hi Tim,

I'm back home and will be starting on the Pike this weekend. I'll be starting off with taping everything around the servo bays and such to make sure to mark everything as needed. I'd sure like to hook up with someone that has done this before to get a better understanding.....anyone available and want to drop by? I'll buy the beer.

Feb 08, 2013, 04:18 PM
Team USA F3F Member
ttraver's Avatar
Hey Ken,

well, I think that I gave you a pretty thorough step by step, so you should be able to do it!

Just take it slow, and double and triple check things, and you'll be ok...

If I was ever up in your area, I would stop by when you were doing it...

Feb 09, 2013, 10:11 PM
Registered User
concreteman's Avatar
I visited Ken today, his Pike will be up and flying in short order. He had it totally under control.

Feb 10, 2013, 12:26 AM
Registered User
Yablonsky's Avatar
Had Warren over today and he help me with my Pike. We got the servo bays all taped off and everything drawn up and lines everywhere And we got the RDS In place and cemented in place and the servo trays locked in place And the wiper arms locked into place in the RDS And the servo trays epoxied into place ... On the left wing.

After Warren left I took on the right wing with a little bit of help from my friend Todd And I got the Servo trays epoxied into place along with the RDS wipers.

I left both wings set aside to dry overnight And then started working on the fuselage.

The servo tray that was in the fuselage was very tight Warren attest to that So I pulled up the front end as it was drooping a little bit and I CA'd The front in place and then I epoxied the rest of the servo tray in place.

I got the servo pockets ground out a little bit so I could get the servos fitted into place. I then predrilled the holes for the screws to hold the servos in place And then I got the v-tails set into place And finally got the v-tail pushrods cut to length and glued and connected to the servos.

Everything is all set in drying overnight.

a couple of photos including one of my templates to make sure that the Flap and aileron servo match from wing to wing

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I HUGE thanks goes to Warren for dropping by and helping out just to get me started!!!

Feb 10, 2013, 12:29 AM
Registered User
Yablonsky's Avatar
Now I just need a little assistance with programming the spectrum DX 18 QQ

Will try to tackle that tomorrow

Feb 10, 2013, 06:22 PM
Registered User
Yablonsky's Avatar
Got the RDS servos installed soldered and buttoned up.

Here's a couple of pics of the ailerons and flaps

Left aileron
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Left Flap
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Right flap
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Right aileron
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I found a DX18 model setup on the Soaring USA site. I'll post a link to that soon.

Feb 10, 2013, 06:48 PM
or GPS, F, J, K, or even TD
FLY F3B's Avatar

DX18 Precision Program


Sorry for my delays in getting back to you. I just sent you a PM, but I figured others might be interested in my setup.

I have 10 flight modes for this model in this program.

Launch A
Launch B
Launch C
Fast Distance
Normal Distance
Slow Distance

Switch B is the main flight mode switch, and switch C is the flight mode modifier switch, and switch A gets you to Thermal mode with the C switch for selecting Float.

Flap stick will envoke landing mode when pulled down a couple of clicks.

When flight mode switch B, is in Distance (middle position), use switch C to select fast distance, normal and slow distance.

When switch B is in Launch position, switch C is used to select Launch a, b and c.

When B is in speed, that is all you get, Speed. Switch C will not do anything when in speed mode.

All mixes are designed for well coordinated maneuvers at the target airspeed, so you will notice a lot of rudder mix in thermal and float modes, as well as landing and launch modes. Speed has the flaps following the ailerons 100% so the wing looks like it has a big flaperon. Launch has 100% differential in the ailerons and the flaps don't move at all with ailerons in launch mode. So ailerons will not move downward at all past the launch camber position due to the 100% diff.


Feb 10, 2013, 07:01 PM
Registered User
Yablonsky's Avatar
Just got the elevators servos all buttoned up and the receiver and battery all in place along with the satellite receiver.

Another pic...

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Feb 10, 2013, 11:35 PM
Registered User
concreteman's Avatar
Way to go, Ken.
Feb 11, 2013, 02:14 AM
Registered User
Yablonsky's Avatar
Final steps are the tail cone and then balance.

Warren says the CG is at 102 mm at the fuse.

I'll be getting the Pike all finished up tomorrow or the next day.

Feb 11, 2013, 04:37 PM
Registered User
Yablonsky's Avatar
Here is a link for the Soaring USA page for the Spektrum DX18 radio & setup.


I've also included the Setup file located on their site for DX18 Sailplane with 2 Ailerons 2 Flaps. It's simple enough to change the Wing setup to a V-Tail.


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