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Great Planes - L-39 Mods. and Radio Questions:

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Great Planes - L-39 Mods. and Radio Questions:

Old 03-13-2011, 11:50 AM
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Default Great Planes - L-39 Mods. and Radio Questions:

Hi Guys,

1. I have the Great Planes L-39, which I am just starting to put together. I know that as planes are built, Modifications develop from issues that arise and as a result better ideas come up while in building stage. I am looking for these or any Mods that may have come up during this building stage.

2. On YouTube, I have seen some L-39 crashes, either resulting from piloting error and or from construction error.

A.) Battery Mods - while bigger batteries will give more power to the motor, these same batteries will add additional weight to the plane and can also cause a nose heavy condition. Even if the C.G. is correct, a hard belly landing may break off the nose of the fuse just in front of the wing because of the weight. Some videos have shown this happen.

B.) From out in the trenches guys, what are the battery sizes being used that seem to work. What batteries give the most power yet get us in the right weight size, with still enough power to have good speed and flight times while keeping the CG correct so it flies good without issues.

3.Now another thing I came across is with the elevator. The pushrod is located and connected to the Elevator on port side. It seems that force of the high air speed keeps the starboard elevator from functioning up and down correctly (Not a Good Thing). So in essence, at full speed, you have only half of an elevator functioning while traveling at the fastest speed the plane will go (Definitely Not Good if this is True?). Any comments on this? Please step up to the Mic and Speak..….

Also if this is true, it may possibly cause a rolling issue with the plane since only one elevator half is working. There may be other issues as well. Has anyone else seen this or experienced this to confirm this issue?

4. Receivers - Guys what receivers are you using for this plane (L-39 by Great Planes). I am looking for some suggestions for receivers in the 72 MHz band. I have a Spektrum DX7 radio in the 2.4 GHz band. However being fairly new to the 2.4GHz systems I am not totally immersed yet in how they work inside and out, so I am standing by my tried and true Futaba 9C super transmitter.

A.) It is my understanding that the 2.4GHz systems are proprietary and use only the receivers of the same name brand as the Transmitters. (Ex. Spektrum Transmitters with Spektrum Receivers, Futaba Transmitters with Futaba Receivers and JR Transmitters with JR Receivers and so on and so forth). No Mixing Hitec Receivers with Futaba Transmitters etc.

B.) Then there are the module systems, but the theory of non mixing of the brands from what I understand is still the same, correct? So I could not get away with using a Hitec 2.4GHZ receiver, with my Spektrum radio, correct? I also have a Futaba 9C super radio that at this time I will use until I learn otherwise about the mixing of equipment. So I am left with looking for a Futaba receiver, small and light enough for the L-39.
While being new to the Park Flyer World, I have noticed that there are Receivers with what they call a short crystal in them, like the Futaba R114F 4-Channel FM Receiver 72MHz Low Crystal. While these may be perfect for slow flyers and park flying the range is only approximately 650 feet or (200m). Which raises a Red flag for me as being rather a short distance, hence the name short crystal. So either one of the Castle Creations, GWS or Hitec receivers below seem so far fit the bill. If there are any other choices of receivers that would work, please let me know

In Summary:

1. Mods: Modifications that may exist. What are they?

2. Batteries: Which will be the lightest yet maintain the power needed.

a. FlightPower - EONX30 (Lite) LiPo - 3S, 11.1V, 1200mAh, 30C - wt. 4 oz.

b. Great Planes - ElectriFly LiPo - 3S, 11.1V, 1250mAh - 20C - wt. 4 oz.

c. FlightPower - EONX 30 LiPo - 3S, 11.1V, 2200mAh - 30C - wt.6.9 oz.

3. Receivers: FM 72MHz – So far these look like my choices for my Futaba radio.

a. Hitec - HFS-05MS 5-Channel SC Micro – Receiver - wt. 0.3 oz.

b. Castle Creations - Berg Microstamp 4L 4Ch. Micro Rx FM - wt. 0.14 oz. (4 grams)

c. Castle Creations - Berg 7P 7Ch FM Programmable Horiz Rx

d. GWS - Naro Receiver 6-Channel Horizontal Pin Futaba

e. GWS - Pico Receiver 4-Channel Horizontal Pin Futaba

I am looking for what will be the best set up for this L-39 plane. A combination of the right battery, with the right receiver and any Mods that would make the plane fly the best it could be and if possible any suggestions or Mods that would make it fly better. So any suggestions and or comments would be much appreciated especially since this is my first electric and I do see some issues that I have seen come up thru various mediums. I was never a real big fan of YouTube, but I see that watching some videos of the L-39 on YouTube has shown me some insight as to how the plane flies. The do’s and the don’ts as I sat and watched other people flying the L-39.


Any comments and /or suggestions please respond.


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