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Mar 09, 2019, 07:48 PM
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Terminater's Avatar
Try using a Spektrum RX instead of the orange one :P
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Mar 13, 2019, 02:10 PM
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hello Terminater
yes I did that before asking to the group. A friend was having a receiver from spektrum, but only 6 channels.

the result was the same if not worst.

I think the problem is the frequency of the BEC as it is 50kHz and seems to disturb the receiver.

Since then I made the Following modifications: changed the receiver to an orangeRx 820 V2 (faster to recover from a lost signal) and less sensitive to the 50kHz.
I also replaced the BEC from the ESC to a separate BEC YEP HV 20A
I also added some external capacitor to the bec 4000µF)

Now all is working fine. And I don't see any new blocking situation with the build of the DC3.
attached picture are signal on a digital memory scope showing:
2207: original signal wave form on the external BEC as original
2208: BEC with capacitors Added
2206: slower recording of same as 2208

Enjoy flying
Apr 05, 2019, 03:47 PM
Registered User
hello,
Some more progress on this bird.
it arrives close to the first flight day. Now all is prepared and almost ready.
Here are some informations and details.
the final take off weight is 3.867kg including:
- a graphène 5000mA, 3S battery 40C or Heavy duty 5000mA 3S 60C
- 2 motors 130gr 1450kV
- propellers Master Air Screw CW and CCW 9x7x3
- 4x servo 9gr for flaps
- 2x servo 18 gr for ailerons
- 2x servo 26gr for direction and elevator
- 1 x BEC 20A
- retractable landing gear
- 85gr lead in the tail for balance (behind the tail weel)
- XT90(from battery) to 2x XT60 (to ESC) + T Dean (to BEC) connector

For first flights:
CG set at 94mm with landing gear retracted
CG set at 97mm with landing gear extended
Ailerons up 3mm
Elevator down 3mm
Flaps at 0°, 10° and 30°
All deflections as recommended in the manual.
All dual rates at 50%
All expo at 30%

If using only 1 motor, the max curent is 52A at start of battery
If using 2 motors the total curent is 84A at start of battery. This shows the limitation of the curent due to battery impedance (RI) and cable between battery and spliter of about 0.016 Ohm.
Total traction with above information is around 3.1 kg.
The selection of a single battery to feed both motors is not a good option. However too late for me as I purchased them already.
The best solution is to use a single battery per motor.
This has 3 benefit:
- there are plenty of 2200~2700mA battery with cheap price because you only need 30C. For example Turnigy 2200 3S 40C is only 15€ each.
- the weight of the battery is lower than equivalent single battery as the weight depend on the C rating. (small weight difference)
- the place to put the battery will be 2 in parallel (aside of each other) which permit also to reduce the lead in the tail as the weight is more backward than with a single battery which is longer.

With the actual 5000mA 3S; the flight duration with only 70% of power will be about 4 minutes. Could be a bit more if power is even lower.
The alarm voltage on the ESC should be set very low like 3.2V ~ 3.3V: as the ESC is at the end of wiring of 0.6m (distance between the battery and the ESC) where I used 12AWG, the voltage drop at around 30A is already ~ 0.36V. So the effective alarm is set at 3.6V at the battery level.
The battery is almost not warming up, happily as there is no ventilation in the fuselage. Temperature of a full discharge at full power (3.5 minutes) is around 39°C

Now waiting for good weather to make the first flight.
I hope I'll have somebody to make a video of it.
Last edited by broty; Apr 05, 2019 at 03:49 PM. Reason: typo
Apr 06, 2019, 12:50 PM
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E-Challenged's Avatar
Re: Tritle Brodak DC-3 Project

Having problems getting started with other model repairs and small work area clutter to get started. Will do build thread in the Scale Electric Kit and Plans forum. Not many of this model built yet.
Apr 16, 2019, 02:00 AM
Registered User
and YES! it flies!!!
after so many waiting time and modifications and questioning, yes it flies. Looks good in the air and on the ground, but the fly is too fast due to weight. So far away from a floating DC3 like the real one.
My first and unique fly (at now) was a lot bumpy. The take off was not a problem, as I maintained it on the ground to gain speed. Then the flight was a disaster: the sensitivity of all gouvern is a lot tooooooooo sensitive. Can not even touch the stick. Also I was so nervous to keep it flying that I forgot I setup dual rates down to 50%. So the fly was barely 3 circuits to have time to reduce the speed a bit and to trim aileron and elevator. Then I land without problem. Ready for the next fly after some throw modifications.
So guys this is the good news: It flies. and it is nice in the air.
Hope to have somebody to film for the next fly.
All settings like above are OK to fly. It seems to be quiet stable with such settings. Hope to go further to anaysing the settings during the next fly.
Last edited by broty; Apr 16, 2019 at 02:02 AM. Reason: typos
Apr 16, 2019, 04:17 PM
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hombresinropa's Avatar
Awesome!!! Do you recommend just 50% expo, or are you going to reduce the throw/deflection by 50%?

Congrats on the maiden! I hope to do mine this weekend
Apr 17, 2019, 02:56 PM
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hello Hombresinropa
Do not recommend anything yet. I have to check again and see if the throw are as explained or if there is some mistake somewhere. Could be I set the values as per the manual but while in 50% mode :-(
I hope to have time to check this weekend.
Apr 18, 2019, 02:30 PM
Registered User
Hello Hombresinropa
As you plan to fly this weekend, I organised to measure the throw.
As I suspected, the throw are good WHEN in 50% dual rate! That's my mistake.! And I almost crashed due to that.
So with the balance point as I set, the throw as on the plan should be OK to start with and then adding a 50% as dual rate and 30% exponential.
This could be a good point to start with.
As just measured, the full throw for
- elevator was 22mm and 50% is 13mm
- direction was 35mm and 50% is 20mm
- ailerons was 25mm and 50% is 14mm (a bit special to figure out as I have differential here)
- flaps 10 degree and 30 degree
I hope I'm still on time for you and so you can make a safe maiden flight.

I'll modify that and come back after the next fly.

Enjoy it, it is beautifull in the air.
Apr 20, 2019, 06:24 PM
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hombresinropa's Avatar

Maiden flight


Flew great but my retracts came loose on takeoff. Had to put it in the grass to avoid ripping the gears apart. Minimal cosmetic damage. Broken prop and slight damage to the leading edge. Easy fixes

It flew great! Power setup was way more than enough.

Had the CG at 95mm. Throws as listed in the manual. Flew it on low rates set to 60%. 30% expo. 2x 5000mah batteries.

Can’t wait to get it up again!

VQ C-47 maiden flight hi def - April 2019 - Alaska - Frontier Fun Flyers (2 min 50 sec)
Last edited by hombresinropa; Apr 20, 2019 at 08:04 PM.
Apr 20, 2019, 08:30 PM
Registered User
Quote:
Originally Posted by hombresinropa
Flew great but my retracts came loose on takeoff. Had to put it in the grass to avoid ripping the gears apart. Minimal cosmetic damage. Broken prop and slight damage to the leading edge. Easy fixes

It flew great! Power setup was way more than enough.

Had the CG at 95mm. Throws as listed in the manual. Flew it on low rates set to 60%. 30% expo. 2x 5000mah batteries.

Can’t wait to get it up again!

https://youtu.be/HYHQZ2DDMcU
How much does yours weigh?
Apr 20, 2019, 08:53 PM
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hombresinropa's Avatar
9.4 pounds flying weight
Apr 21, 2019, 12:58 AM
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Terminater's Avatar
Next time hold the phone sidewards heheh
Apr 21, 2019, 02:39 AM
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congratulation. Well done. At least it is flying even at that weight.
but why 2 x 5000 mA? that's a lot. and weight too.
Better use 2x 2200 or 2500. You will spare 1 pounf of battery!
The lighter the best it flies
Good luck for the next one.
enjoy this beauty in the air.
Last edited by broty; Apr 27, 2019 at 03:18 PM. Reason: spelling
Apr 21, 2019, 11:39 AM
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hombresinropa's Avatar
I went with the 5000mah batteries because 1) I already had them, 2) I want more than 4 minutes flying time, and 3) wanted to see if this weight was flyable.

I really wanted to get it in the air - part of my impatience was forgetting to put threadlocker on the gear. That's why it came off on the gravel runway. Glad I didn't put the cowls on yet. Next flight will be on our grass runway. I’ll fly once or twice more with the 5000mah batteries and see how much power this is actually draining during flights. If I can squeeze 6 minutes out of 2x2200 batteries I will switch them because you are right, it would be nice to be lighter. It's good to know that it will fly at this weight though - I have some plans to add some things to the plane that will make it heavier.

By the way, thanks for the details on your build, broty! It helped get me motivated to get mine up in the air! Great work on yours!
Last edited by hombresinropa; Apr 21, 2019 at 12:41 PM.
Apr 21, 2019, 03:31 PM
Registered User
ok, I went for a new session today.
2 flights. both OK no problem. Since I changed the elevator throw back to normal, it is really flyable. With the 5000mA 40C battery, I flew 8 minutes. Mostly at 1/2 (or around) throttle. With my setting, it is enough power for flying. Flaps 10° is OK with a bit of gaz down, flaps 30° need compensation.
This time aI made a video but the camera man was not the best, however he was the only one so at least the best I can get . The video is now 550MB but I'm sure I can not post that much here. what is the limitation of size?


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