On the off option. Be careful, if the surface has a balance tab it could free wheel full up or down. You may wonder how I know this. Did land but with some puckering. BTW this was a wire failure nothing to do with RXs.

Yes, you definitely do NOT want to use the OFF feature of the failsafe for a surface that move! I have seen a few test cases myself that even without balance tabs surfaces move and get stuck in an overthrow condition (that would not normally happen when the servo is driven). Ugly, ugly, ugly when that happens!

The OFF feature was added after many people requested it so that they could monitor failsafe conditions and use auto-pilots that watch the PWM pulse from the receiver to enable the auto-pilot mode.

Originally Posted by JimDrew

I DON'T recommend splitting the surfaces UNLESS you are going to set the failsafe to a neutral position for each controlled surface. A good example of a potential problem is if two receivers were to control each elevator half. Even if one surface went neutral because of a failsafe, pulling or pushing the functioning elevator half would induce a roll. It all depends on your personal preference of what happens during a failsafe. The good news is that we really don't need to worry about signal loss.

Success with your own company Jim !!

My large 1/4 scale Super Cub flew like a dream with the two nanos. I have split surfaces, with failsafe to neutral as you recommended.
The preflight range test was very good, I guess about 50 meters +. But still i have some doubts regarding the Nano´s installation.

The Nano´s placed way back in cockpit, on each side of fuse.
Antenna´s in line with the direction of flight, but higher than electric motor, esc, etc with about 10-15 mm clearance (when flying level).
The places meet the requirements.

Questions:
1. I was looking around for a radiation pattern with distance measurement for the Nano´s. Have you made one?

2. Should I rather have antenna orient 45 or 90 degrease on flight direction, or is the range in the weakest part of radiation still sufficient (Pointing towards transmitter on loooong final approach).

Nice plane!

I never made a radiation pattern, but it is a standard dipole with a tuned circuit, so I expect the 'doughnut' to be off a little bit to one side.

Keep in mind that the two wires form a single antenna. So, with the wire stretched out, the parallel lines running from both sides of the receiver are the narrowest point of that doughnut. So, with your setup the absolute worst case (and how you should be range checking) is with the nose (or the tail) of the aircraft pointed directly at you. If your range testing is good that way, then you won't have any issues as the signal reception only improves the closer you get to perpendicular to antenna axis (the side of your plane in your case).

MAKE SURE that those wires for the flaps and ailerons are NOT moving anywhere near the antenna!!!! I can't stress this enough. If those wires passed over the antenna, the antenna tuning changes completely and you can lose all signal! Use some type of wire holding device (rubber bands work great for cases like this) that prevents the wires from just dangling and moving around.

Jim,

I've been flying my Four Star 120 on two Nano receivers as situated as in the first figure (airplane top view). The aft rx with the antenna parallel to the flight path has the rudder, elevator, and throttle servos, the forward one with the antenna parallel to the wingspan has the ailerons and flaps. No problems, but your advice on the orientation is interesting and if I can improve things I'm open to ideas.

Would rotating both receivers as seen in the second diagram improve the reception for a wider set of typical orientations? I'm thinking that the aft one (that used to be parallel to the flight path) might have improved reception when flying head on, like on landing approaches.

What do you think? I am having trouble picturing that dipole doughnut thing relative to the shape of the Nano Rx and its antenna wires.

Thanks,

Paul

orientation to each other is not important as they're not working together for diversity. I don't think their orientation is anywhere near as important as what you can do to get them separated from other equipment and flopping wires. I've just been using velcro to stick them to the sides of the turtledeck on my aerobatic planes...

Is this correct? Nano in red on an image taken from google. The figure eight shape is a cross-section of the "doughnut."

KM - Thanks for the clarification about the two Rxs not working together to achieve diversity. I am mostly concerned with the orientation of each Rx with respect to the transmitter in my hands on the ground - and I'll check my wiring for movement in the area of the Rxs.

Come to think of it, in what direction is the strongest signal coming off of the transmitter antenna?

Thanks,

Paul

Originally Posted by FlyingW

Come to think of it, in what direction is the strongest signal coming off of the transmitter antenna?

Thanks,

Paul

From the sides at the tip... that's why you should not point the antenna directly at the model....

Originally Posted by JimDrew

Nice plane!

I never made a radiation pattern, but it is a standard dipole with a tuned circuit, so I expect the 'doughnut' to be off a little bit to one side.

Keep in mind that the two wires form a single antenna. So, with the wire stretched out, the parallel lines running from both sides of the receiver are the narrowest point of that doughnut. So, with your setup the absolute worst case (and how you should be range checking) is with the nose (or the tail) of the aircraft pointed directly at you. If your range testing is good that way, then you won't have any issues as the signal reception only improves the closer you get to perpendicular to antenna axis (the side of your plane in your case).

MAKE SURE that those wires for the flaps and ailerons are NOT moving anywhere near the antenna!!!! I can't stress this enough. If those wires passed over the antenna, the antenna tuning changes completely and you can lose all signal! Use some type of wire holding device (rubber bands work great for cases like this) that prevents the wires from just dangling and moving around.

Thanks for the reply and suggestions Jim.
Suspected it was a dipole. Had that in mind the whole time, but the rangetest was going to deside if I would fly it or not.
And yes, tale in/out was what I focused on during range test, with good result.

Actually not easy to find The perfect place for two nanos. The 2" rule includes the distance between Nano antennas as well I guess.
Perpendicular to direction was my first choise, but impossible to do without even more servowires.
Anyway, not going to take any more chanses, will change the antennas direction.
The flaps and ailron -wires where secured with nylon ties, but I will add some rubber band inside wings to keep them stretched.

Originally Posted by FlyingW

Come to think of it, in what direction is the strongest signal coming off of the transmitter antenna?

Thanks,

Paul

The same as the Nano antenna.
Do not point TX antenna towards the airplane...

Yep, you guys are all correct on your theories. Nanos do not work together to provide any type of diversity. However, I have thought about making the bigger power expander (XPander+) with the ability to use two Nanos for diversity. You would have to program them as Master/Slave, and only the master could be programmed for channel mapping, offsets, and reversing. But this would be a way to get true diversity. We had the satellite receivers for that - as a big request by Graupner. They soon learned that it didn't make a bit of difference in the real world. Both receivers would have signal loss at nearly the same time. So, I am not sure how much sense it makes to provide diversity support other than making someone feel warm and fuzzy because they spent more money for an extra receiver that they really didn't need.

Thanks for all your explanations.

I suppose if the radiation patterns of both the Tx and Rx were both spheres, then any orientation would be optimal.

Given the doughnuts and lobes and such of the real-world emissions of these devices, and the evidence from flying that the signal strength is strong enough in any orientation my planes have experienced, I am happy with the product as is.

I want to go flying.

Originally Posted by theKM

orientation to each other is not important as they're not working together for diversity. I don't think their orientation is anywhere near as important as what you can do to get them separated from other equipment and flopping wires. I've just been using velcro to stick them to the sides of the turtledeck on my aerobatic planes...

Hi. I am curios.
I see you have a vertical orientation of antennas in your installation. How is the range in the formal range test compared to Horizontal orientation ? Thinking doughnut radiation pattern. Obviously, you should get the weakest signal flying level high straight above you.
But than again, you might just only hover, which makes antennas horizontal

Originally Posted by JimDrew

Nice plane!

I never made a radiation pattern, but it is a standard dipole with a tuned circuit, so I expect the 'doughnut' to be off a little bit to one side.

So, with your setup the absolute worst case (and how you should be range checking) is with the nose (or the tail) of the aircraft pointed directly at you.

I just changed mine two nanos in the 1/4 scale Super Cub - to a V shape, horizontal orientation, just a bit over 2" apart tip-tip. Now have to wait on nice weather to range test it.
Any experience with V shape config.?
To which side will the Radiation be off?

If you are going to do a V shaped, I would recommend tipping the V inwards towards the front of the plane. Otherwise, on final you could end up standing the same angle as the outward pointing V.

In reality, it probably makes very little difference as the range is about 1/2 if both antennas are pointing perfectly at each other. So, half of mile or so (at ground level) is probably further out than most fly anyways.

Originally Posted by JimDrew

If you are going to do a V shaped, I would recommend tipping the V inwards towards the front of the plane. Otherwise, on final you could end up standing the same angle as the outward pointing V.

In reality, it probably makes very little difference as the range is about 1/2 if both antennas are pointing perfectly at each other. So, half of mile or so (at ground level) is probably further out than most fly anyways.

Thanks for replying. Jim.
At some point one of The Antennas will point at The RC pilot.

Ok, so V shape is not a good choise.
With one receiver, antennas should point perpendicular to direction

What would you recommend with 2 Nanos in the same plane, and can't have both perpendicular to flight direction?
A slight V shape, L shape , H shape , vertical and Horizontal differential....TheKM style ...

I want The very best solution possible in this plane.