Bird of Time Balsa Kit Build Thread

[TexMechsRobot]

I put some work into the transmitter today and made some progress. Here's a terrible video explaining where I am and what I need.

Right after I made the video I came here to post and remembered Craftydan's post. Using that, I was able to fix my Rudder issue. So the video will be wrong on this one point:

I have the rudder mixed to cancel itself out and then also mixed to be controlled by the aileron channel.​

The only thing left to do is:

1. Get the spoilers to not be controlled by the aileron stick.
2. Put the spoiler control on the throttle (unnecessary?)​

I like the flight modes method since I can mix elevator in on launch and landing to compensate for the motor and spoilers.

I really appreciate all of your help so far and can answer any specific questions you might have in the process of helping me troubleshoot.

 

[TexMechsRobot]

I figured out the Spoiler/Rudder issue. I used Craftydan's suggestion to do the same thing to the spoilers. I mixed the aileron input to cancel out the right spoiler motion and the left spoiler is already slaved to it. So now, the only "issue" is that I can't control the spoilers with the throttle stick.

I tried mixing the motor to the right spoiler but that didn't seem to do anything.

 

[Konrad]

...
2. Put the spoiler control on the throttle (unnecessary?)[/INDENT]

I like the flight modes method since I can mix elevator in on launch and landing to compensate for the motor and spoilers.

I really appreciate all of your help so far and can answer any specific questions you might have in the process of helping me troubleshoot.

I think that the spoilers need to be on the throttle stick. This is assuming you fly power on the side, along with gliders.

The reason I say this, is that while landing I assume you control the glide slope with the throttle on your power planes. With gliders this same glide slope control function is done with the spoiler. If you place the spoilers on the throttle you DON"T need to relearn how to land as the muscle memory is much the same. If landing short move the throttle/spoiler stick forward. If over shooting the landing zone pull the throttle/spoiler stick back.

All the best,
Konrad

 

[TexMechsRobot]

I think that the spoilers need to be on the throttle stick. This is assuming you fly power on the side, along with gliders.

The reason I say this, is that while landing I assume you control the glide slope with the throttle on your power planes. With gliders this same glide slope control function is done with the spoiler. If you place the spoilers on the throttle you DON"T need to relearn how to land as the muscle memory is much the same. If landing short move the throttle/spoiler stick forward. If over shooting the landing zone pull the throttle/spoiler stick back.

All the best,
Konrad

This was my thought process as well. Actually getting the radio to do this...that's another story. Still lost there.

 

[Konrad]

Lets see if I can help there? First my disclaimers: You are getting what you paid for. I also am not comfortable with the Spektrum (asian) master slave concept of mixing. I actually like the Multiplex and Fr-Sky object oriented mixing concepts.

Before we do any radio set up we need to define what we want before we can tell the radio what to do.

So I'll start with what I think I understand as your requirements. I assume you are flying mode 2.

On the right stick you want elevator, and primary directional control (rudder).

On the left stick, non centering action, you want lift control (spoilers)

On the rear slider (on the back left side) you want throttle control.

And as a Safety feature you need a motor lock out switch.

Before I go any further I have to ask is this correct? I also need to know how many servos controls are there in the model? I also need to know how many outputs are available from the receiver.

Yes, I too own a DX9, so I should be able to work out a mixing plan in real time!

All the best,
Konrad

 

[TexMechsRobot]

Lets see if I can help there? First my disclaimers: You are getting what you paid for. I also am not comfortable with the Spektrum (asian) master slave concept of mixing. I actually like the Multiplex and Fr-Sky object oriented mixing concepts.

Before we do any radio set up we need to define what we want before we can tell the radio what to do.

So I'll start with what I think I understand as your requirements. I assume you are flying mode 2.

On the right stick you want elevator, and primary directional control (rudder).

On the left stick you want lift control on the non centering action (spoilers)

On the rear slider (on the back left side) you want throttle control.

And as a Safety feature you need a motor lock out switch.

Before I go any further I have to ask is this correct? I also need to know how many servos controls are there in the model? I also need to know how many outputs are available from the receiver.

Yes, I too own a DX9, so I should be able to work out a mixing plan in real time!

All the best,
Konrad

Thanks for the support. Very close on your assumptions and I'm glad you started by defining these. It should help us figure this out.

I assume you are flying mode 2. --Correct

On the right stick you want elevator, and primary directional control (rudder). --Correct

On the left stick you want lift control on the non centering action (spoilers) --Correct

On the rear slider (on the back left side) you want throttle control. --Incorrect

And as a Safety feature you need a motor lock out switch. --Correct (I think)

I also need to know how many servos controls are there in the model? --4; Rudder, Elevator, Right Spoiler, Left Spoiler

I also need to know how many outputs are available from the receiver. --6; Throttle, Aileron, Elevator, Rudder, Gear, Aux 1


I'll deal with the two that need explaining from above. I want the motor controlled by a 2 position switch (right now it is on Switch H on the DX9). I don't necessarily need a separate lock out switch since Switch H is doing this.

I basically have it programmed exactly like I need at the moment EXCEPT the spoilers being controlled by the Throttle stick on the DX9.

 

[Konrad]

You really need a safety lock out. That is it takes two distinct inputs to bring the motor to life. They can be 2 switches. Using only one switch (or slider) is not safe as it is all too easy to accidentally flip it on. With two switches you have to accidentally switch both switches to the on state.

Why do you want to have the full torque of the motor coming on when you fly (on - off control)? I assume your ESC allows throttle control. There is a neat trick to help you drop out of the sky should the spoilers not be enough. Bringing the throttle up to just above idle allows the prop blades to come out adding a lot of drag to the airframe.

 

[Konrad]

I also need to ask what kind of mix corrections if any you would like? I NEED to mix in about 18% up elevator with the deployment of spoilers. I also NEED a throttle to elevator mix to keep the power on zoom and loop under control, often about 12% down. I assume you have about 6° of down thrust already built into the fuselage.

All the best,
Konrad

 

[TexMechsRobot]

I could get on board with two switches but I'll put that aside for now. Concerning having the motor on a slider, I won't need to spin the prop to dethermal. That's what the spoilers are for.

 

[nhk750]

I made a sticky note to keep in my radio box so I can remember some of the switches and what they do. The more complex the switching, the more I tend to forget, so I review my note before flights, because you wont have that chance once in the air. Yours sounds like a complex one and a fun one too!

 

[Konrad]

So as not to loose what you already have, select another model memory for this programing

As the DX9 does not recognize RESm models we will need to treat the model's rudder as if it were the ailerons. This is actually ok as ailerons are usually thought of as the primary directional control and that is how we are using the rudder. I also didn't see a control called spoilers. So I'm calling Gear as my spoiler input.

I'm going to first try a simple set up with the spoilers on a Y cable

From the System Set Up, Model Type select Sailplane Type

From the System Set Up, select Sailplane Type
Wing: 1-servo
Tail: normal
Motor: L Lever (if you really don't want the versatility of proportional throttle command we can work on that later.)

Again from the System Set Up, I went to RX Port Assignment I have
1 THRO:Motor
2 AILE: Aileron
3 ELEV: Elevator
4 RUDD: Gear
All other RX outputs are Inhibit

Going to Channel Input Config (the [NEXT] in RX Port Assignment)
I have
1 Thro: N/A (its a default)
2 Aile: N/A (its a default)
3 Elev: N/A (its a default)
4 Rudd: N/A (its a default)
5 Gear: Thr

For this simple model no flight modes are selected.

Go back to Main Screen, Function List
Go to Throttle Cut
Select the "inhibit box" and then activate which ever switch you want as your kill switch. I've chosen Switch A. The default is -130% with the "on" being back towards me, the on is the kill position (1)

In the Mot curve select the "inhibit box" and move lever "L"

Now going to Function list select Monitor
You should see only the elevator move when the elevator stick is moved
You should see only the Aileron move when the Aileron stick is moved
You should see only the Gear move when the throttle stick is moved
You should see only the Mot move when the "L lever" is moved and the "A" switch is in the 0 position (off, back away from you)
With the "A" switch in the 1 position (towards you) you should see the MOT bar in the monitor pointed down. And no amount of moving the "L" lever will make anything move on the Monitor screen.

Now plug in your esc in the first channel of your RX. Plug in the rudder servo into the second channel of your RX. Plug in the elevator into the third channel of your RX. And plug in your "Y"ed in servos for the spoilers into the 4 RX socket.

Next I'll work on the mixing. This is assuming both spoiler servos are moving the correct way. If not we will need to set up a more complicated mix that allows you the reverse the spoiler servo direction independent of each other.

Let me know if the spoilers are moving together.

All the best,
Konrad

 

[Konrad]

I'm going to assume it didn't work.
So going back into the System Set Up, I went to RX Port Assignment I have added another gear to the fifth RX output. As far as the TX is concerned both outputs are now controlled by the throttle stick. Going back to the Function List under Servo set up you can now reverse one of the two gear channels

Mixes to come after dinner.

All the best,
Konrad

 

[Konrad]

Now for the two mixes.

Under the Function List go to Mixing
There you should see what the radio thinks you might want to mix. In the case of this simple set up you should see AIL>RUD Inh
As we don't have ailerons leave it Inh
Go down to P-Mix 1 this will be our spoiler to elevator mix (remember gear= spoilers)
In the first line you put GER>ELE
Select curve (I like curves for future fine tuning)
Move the throttle stick to see a screen flash on and off saying add or delete point. Play with this a bit to learn how and where to add points.
I like to add all 7 points if I can.

Now spoilers are a bit weird, in that at the very beginning of their deployment they often aid in adding lift. So my second (Actually number 6 point as the points are labeled from idle to full throttle) is going to add about 6% down in my case. My third point number 5 will be a neg number -4% for the start of up mixing. Keep going to the points until you're at point 1. I think you will need about neg 20% (up).

I would have my mix curve looking like;
Point 1 -20%
Point 2 -16%
Point 3 -11%
Point 4 -8%
Point 5 -4%
Point 6 +6%
Point 7 0%
Switch is ON

Back to Mixing look for P-MIX 2 this will be you power to elevator down mix.
Select [curve]
Then in the 2 boxes labeled Inh change these to read MOT>ELE
I have 3 points to start with
You want to add a down mix as you move the "L"lever to the center back of the TX
My mix points look like:
Point 1 20%
Point 2 9%
Point 3 0%

Switch is on and trim is Inh.


For the spoiler servos try to set up your linkage so that you can use close to the full range of servo motion. You want the spoiler to pop up at least 70°.

Don't be afraid to use the sub trim to get a balanced feel to the spoilers (minimize roll). "Travel" and "Abs. Travel" are also helpful in getting the most from your servos.

When tuning a glider you want to keep moving the center of gravity aft as you narrow in on your trim setting. The closer you are to a neutral center of gravity trim the less work you will have as the speed of the glider changes. (Read the less down trim you will need as you add power, or dive between thermals ) Now the opposite might be true of the spoilers, you might have to add more up compensation when the spoilers are deployed.


Double check surface and mix directions before first flight!
Let us know if this helps. And more to the point let us know if this doesn't!

Your Bird of Time should wind up being a real nice "Raiden XL killer"

All the best,
Konrad

P.S.
Do you have about 6° of down thrust set into your motor mount? If not you might need more down MOT>ELE than I state.

 

[Konrad]

Now if you insist on a switch for the motor it is simply a function of selecting which switch you want, rather than the "L Lever" I used.

Go back to Main Screen, Function List
In the Mot curve select the "inhibit box" and move whatever switch you will be comfortable using as the motor on off switch.

Go to Throttle Cut
Select the "inhibit box" and then activate which ever switch you want as your kill switch. I've chosen Switch A. The default is -130% with the "on" being back towards me, the on is the kill position (1)

I've found that adding full power near a stall is dangerous in that the torque can drive a wing down into the ground. I also don't like the control limitation that on-off power systems demand.

All the best,
Konrad

 

[TexMechsRobot]

I didn't see your posts until I got to work this morning. I won't have time to try this out until much later, maybe even Thursday evening. I appreciate the very detailed response!

 

[Konrad]

Not a problem, this is a hobby not a job.

Wow, you are allowed to view these forums from work? My employers blocked all forums. You had to request access to the ones that supported your professional interests (Job).

All the best,
Konrad

 

[Konrad]

Looking at some of your photos I don't see any down thrust built into the fuselage.

I'm a mechanical engineer and as such I don't like to use "programed" fixes as a means to address issues. I tend to want to do things in the analog world before resorting to "1" and "0".

I'd recommend you break off the nose and point the motor down about 4° to 6° and to the right about 2°. This shouldn't be too traumatic as you have seen fit to give the nose a nice contrasting color (paint).

All the best,
Konrad

 

[TexMechsRobot]

Looking at some of your photos I don't see any down thrust built into the fuselage.

I'm a mechanical engineer and as such I don't like to use "programed" fixes as a means to address issues. I tend to want to do things in the analog world before resorting to "1" and "0".

I'd recommend you break off the nose and point the motor down about 4° to 6° and to the right about 2°. This shouldn't be too traumatic as you have seen fit to give the nose a nice contrasting color (paint).

All the best,
Konrad

I'm glad you stated your qualifications or else I wouldn't have given any credence to your suggestion.

I'm not breaking the nose off and will rely on the stabilator and rudder to compensate for flight characteristics under power. Too much retro work when the fix can be done in the digital world.

 

[Konrad]

Well, the elevator compensation (Computer down mix) will not work if you don't have enough airspeed. If you are not going to add down thrust be ready to add a lot of down trim and fast trying to avoid the Fig.9 that might end at the back of your feet as you power up!:black_eyed: Even more so if using an "ON" "OFF" motor switch.

All the best,
Konrad

 

[TexMechsRobot]

I got to maiden it last night. It went as well as could be expected and I figured out a few things to fix.

First off, I absolutely MUST get the programming of the radio right. The current setup is doable but not ideal. In some ways, it's downright dangerous. I'm going to spend as much time as necessary to get my transmitter doing these things before I fly it again:

1. Double switch the motor. Both 2 position switches will need to be up in order to activate the motor. It will be a full on or full off motor activation.
2. Program the spoilers to the throttle stick for fine control.
3. Mix down elevator with motor on to help control the climb.
4. Mix up elevator with spoiler deployment to help with landing.

It doesn't seem like a lot but currently, none of those things are happening and any one of them not working could spell disaster at the slightest mistake.

I also learned that Konrad was absolutely right about down thrust. His method of fixing it is not my favorite. I plan to add spacers to the motor mount to tilt the motor downward if there is enough room inside the nose to keep the motor case from binding against the top. If this doesn't give me enough angle, then I'll consider more drastic measures.

I need to increase the travel groove for the stabilator so that it has more upward deflection. It currently reaches the limit of motion before I run out of servo actuation or stick motion. I can increase it by 1/8" and solve that problem.

As for the maiden, it went well. I opted to let another glider expert at the club be on the sticks as he had decades of experience (including international wins) and I did the tossing. We were dealing with about 4-5 mph steady winds gusting to about 9 mph at times. It literally gusted right as I was letting go and tilted the left wing up so I released it a little sideways. I also threw it a little down (too much) because I was worried about stalling it on the throw. Sherman compensated beautifully and it glided easily to rest. There is no expo and the throws are at full so I imagine it was a bit twitchy to deal with. I won't know what to adjust until I get on the sticks myself. The balance looked good but again, I'll need to fly it myself to really dial it in.

We reset and decided to do a powered launch since everything seemed to be working well. As you can hear in the video, I barely tossed it and the BoT had plenty of power and just jumped out of my hand. This is where we learned that it wanted to do the figure 9 VERY badly. Sherman quickly ran out of elevator trim and still had the stick giving nose down to control the climb. As stated earlier, I can fix this by giving it some down thrust and mixing in elevator for the climb. He pulled it up to a decent altitude for a glide out. On the downwind turn, two things happened. One, the wind gusted again and lifted the left wing. Two, Sherman has basically only flown 6 servo sail planes for the last 15 years and tried to coordinate his turn from muscle memory but there is no rudder input on the left stick. Thankfully, he was able to save it without any trouble. But it was a scary moment I have to say. Even he yelped a little and I felt bad from him! The landing was a little hairy since it was running downwind at a lower altitude and he wanted to turn it back to us so it didn't land too far away. It dragged the right tip a little but no damage was done at all. It really was pretty gentle and I expect I'll do much worse over the coming months. There is a slightly audible "click" as it touches down. At first, I thought it was the sound of balsa snapping somewhere but realized it was just the left propeller blade bouncing off the ground and then clacking against the fuselage.

After that flight, I decided that there wasn't much else to learn until I fixed the above issues. I was flyable and I could have taken it up but the risk wasn't worth the reward. I exercised patience, packed it all away, and pulled out the Radian to get some easy flights in.

All in all, it was a success in my book. I plan to work on the items above and then wait for another nice weather day.