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-   -   Skymaster L-39 Assembly and Scheme Change (http://www.rcuniverse.com/forum/rc-jets-120/10013139-skymaster-l-39-assembly-scheme-change.html)

k_sonn 09-19-2010 04:51 PM

Skymaster L-39 Assembly and Scheme Change
 
1 Attachment(s)
I started assembling the Skymaster L-39 today. I started with hinging the rudder. The first thing I noticed was the pre-drilled holes for the pin hinges in the trailing edge of the verticle stab did not line up with the pre-drilled holes in the rudder. I elected to fix this by drilling out the pre-drilled holes in the trailing edge of the verticle stab and epoxying inch and a half longpieces of 1/4 inch hard wood dowel (photo 1). The holes were drilled to line up with the pre-drilled holes in the rudder (photo 2). The hinge line was found and reliefs were filed into the leading edge of the rudder so the pin hinges could be recessed (photo 3). The last two photos show the rudder installed.

Kirk

trioval00 09-19-2010 05:18 PM

RE: Skymaster L-39 Assembly and Scheme Change
 
hey Kirk, keep doing what your doing. I had the same issue with mine. I filled the holes on the fuse end of the rudder , layed a strip of balsa over that, then re drilled.
here is a link to a great building thread on the Skymaster's L-39.

[link]http://www.rcuniverse.com/forum/m_9076297/mpage_16/key_/tm.htm[/link].....

you will enjoy this jet, very easy to fly and and moves along really nice with a P-80 in her.

Are you planning on attending Hamburg's Jet Jamboree? I will have mine there and will be able to answer any question you might have..

If you should have any other question. ask.


Mark

k_sonn 09-20-2010 11:28 AM

RE: Skymaster L-39 Assembly and Scheme Change
 

Quote:

ORIGINAL: trioval00

hey Kirk, keep doing what your doing. I had the same issue with mine. I filled the holes on the fuse end of the rudder , layed a strip of balsa over that, then re drilled.
here is a link to a great building thread on the Skymaster's L-39.

[link]http://www.rcuniverse.com/forum/m_9076297/mpage_16/key_/tm.htm[/link].....

you will enjoy this jet, very easy to fly and and moves along really nice with a P-80 in her.

Are you planning on attending Hamburg's Jet Jamboree? I will have mine there and will be able to answer any question you might have..

If you should have any other question. ask.


Mark
Thanks Mark. DId you come across any other issues during your build?

I've read through that build thread a couple of times. It is an execellent build thread. I started this one because I will be changing the scheme and didn't want that changing the direction of the build thread.

Iwon't be able to make it to Hamburg. I'm in the Pacific Northwest until early March.

Kirk

trioval00 09-20-2010 12:46 PM

RE: Skymaster L-39 Assembly and Scheme Change
 
1 Attachment(s)
Kirk, the only other major issues , and they are not really that big is,

1st, if you are using the gear that came with the kit, it's a must, get the BVM upgrade gear springs. mine collapsed on the first time I wanted to do a run up at the airport, and it set me back a few weeks before first flight.

2nd, again, if you are using the gear that comes with it, the nose of the L-39 will sit a little to low. On my first flight, it took a long time to break ground. my sollution was to add a 1/4 square stock to the rails, this will lower the gear 1/4 inch and solved all my problems. you might have another sollution.

3rd. Turbine, I set my thrust tube in as far forward as possible, then I set the P-80 accordingly. I wished the pipe was 2 inches longer but......... and for the balance I installed all 3 batteries in the nose. I use 2- 2300 nimh 6.0 volt and 1- 3500 nimh 7.2 Venom brand battery for the ECU, and with this set up, I only had to add a little weigth to the front. Yors will come out tail heavy, they all do.

4th. I built most of the electronics and gear under the cocpits, but in the rear compartment, I installed all the important gear, such as, on/off switches, air fill valves, propane and kero fills, I/0 board. this would make it easy not having to pull the cockpits out every time I go to fly.....

in the pic you can see the turbine stuffed into the inlet, I nolonger have it there. as I mentioned, set the tail pipe so it just clears the tail, then set the turbine.

enjoy and hope this works................

k_sonn 09-26-2010 08:35 PM

RE: Skymaster L-39 Assembly and Scheme Change
 
1 Attachment(s)
Since I'm changing the scheme I wanted to remove the paint before working on the install. This time I decided to strip the paint instead of samding it off. I used CitriStripe and it worked well. It took 2 coats to strip the vertical and horizontal stabs and 3 coats to strip the rear section of the fuse (the red and blue paint was pretty thick). The 1st photo shows the rear section of the fuse before applying the striper. The 2nd photos shows the results of striper after sitting for about 20 minutes. The 3rd photo shows what the first coat of striper removed. Two more coats were applied to completely remove the red and blue paint. The 4th and 5th photos shows the results after the last coat of striper is removed and the surface is washed with CitriStrip Cleaner and steel wool.

Kirk

k_sonn 09-26-2010 08:40 PM

RE: Skymaster L-39 Assembly and Scheme Change
 

Quote:

ORIGINAL: trioval00

Kirk, the only other major issues , and they are not really that big is,

1st, if you are using the gear that came with the kit, it's a must, get the BVM upgrade gear springs. mine collapsed on the first time I wanted to do a run up at the airport, and it set me back a few weeks before first flight.

2nd, again, if you are using the gear that comes with it, the nose of the L-39 will sit a little to low. On my first flight, it took a long time to break ground. my sollution was to add a 1/4 square stock to the rails, this will lower the gear 1/4 inch and solved all my problems. you might have another sollution.

3rd. Turbine, I set my thrust tube in as far forward as possible, then I set the P-80 accordingly. I wished the pipe was 2 inches longer but......... and for the balance I installed all 3 batteries in the nose. I use 2- 2300 nimh 6.0 volt and 1- 3500 nimh 7.2 Venom brand battery for the ECU, and with this set up, I only had to add a little weigth to the front. Yors will come out tail heavy, they all do.

4th. I built most of the electronics and gear under the cocpits, but in the rear compartment, I installed all the important gear, such as, on/off switches, air fill valves, propane and kero fills, I/0 board. this would make it easy not having to pull the cockpits out every time I go to fly.....

in the pic you can see the turbine stuffed into the inlet, I nolonger have it there. as I mentioned, set the tail pipe so it just clears the tail, then set the turbine.

enjoy and hope this works................
Thanks for the info Mark. I ordered the landing gear spring and fuel tank fitting upgrades from BVM. Nice install.

Kirk

k_sonn 10-19-2010 09:03 AM

RE: Skymaster L-39 Assembly and Scheme Change
 
1 Attachment(s)
Finally completed the paint stripping. The airframe is now 2 pounds lighter.

Kirk

smchale 10-23-2010 01:20 PM

RE: Skymaster L-39 Assembly and Scheme Change
 
Kirk,
Nice work. Amazing that you were able to pull that much weight out just by removing paint. Bet you can see surface detail again?
What scheme are you going to go with (I assume you aren't going to leave it in this winter scheme!? :) ).

AnthonyW 10-23-2010 07:15 PM

RE: Skymaster L-39 Assembly and Scheme Change
 
Curious,
Could you not get a all primer version?

k_sonn 11-01-2010 08:09 AM

RE: Skymaster L-39 Assembly and Scheme Change
 
1 Attachment(s)
More progress...
Photo 1 - Panels going into the rear fuse section were fuel proofed and the components were laid out and installed. The UAT craddle was glued together and fuel proofed.
Photo 2 - The ECUpanel installed. It's screwed to a piece of 3/8 square piece of bass wood that's epoxied to the bottom of the turbine mounting rail.
Photo 3 - The fuel panel and UAT craddled installed (the same way as the ECU panel).
Photo 4 - The power panel clamped in place. Ineed to make some mounting blocks.
Photo 5 - The pipe is installed. BVM has an interesting way of installing the pipe using carbon fiber rods. Works really well.
Photo 6 - All major components installed.

Kirk

k_sonn 11-01-2010 08:11 AM

RE: Skymaster L-39 Assembly and Scheme Change
 
Thanks. Still looking at schemes.

Quote:

ORIGINAL: smchale

Kirk,
Nice work. Amazing that you were able to pull that much weight out just by removing paint. Bet you can see surface detail again?
What scheme are you going to go with (I assume you aren't going to leave it in this winter scheme!? :) ).

k_sonn 11-01-2010 08:13 AM

RE: Skymaster L-39 Assembly and Scheme Change
 
Icould have ordered an all white one but I got this one on sale for less than the cost of the white one.
Quote:

ORIGINAL: AnthonyW

Curious,
Could you not get a all primer version?


k_sonn 03-30-2012 01:04 PM

RE: Skymaster L-39 Assembly and Scheme Change
 
1 Attachment(s)


I started this project a couple of years ago and got side tracked with a few other projects, but now it's time to come back to this one.</p>

The elevator servos (photo 1) and flap servos (photo 2) have been installed. I deviated from the instructions and mounted the elevator servos to the side of the fuse so that the horizontal stabs slide right over them.

I did run into a problem when attempting to install the aileron servos. The ply servo mounts were either installed a little too far forward or the servo covers were cut in the wrong location (photo 3). To solve this I was thinking about cutting the servo opening further forward so I can get to the forward mount and make new servo covers. Any other ideas?</p>

Last couple of photosshow the scheme I have settled on.

Kirk</p>

smchale 03-30-2012 04:39 PM

RE: Skymaster L-39 Assembly and Scheme Change
 

Quote:

ORIGINAL: k_sonn

I did run into a problem when attempting to install the aileron servos. The ply servo mounts were either installed a little too far forward or the servo covers were cut in the wrong location (photo 3). To solve this I was thinking about cutting the servo opening further forward so I can get to the forward mount and make new servo covers. Any other ideas?</p>

Last couple of photos show the scheme I have settled on.

Kirk</p>
Kirk, nice to see you back on this. I'd remove the servo tabs altogether and use Marc's servo dock system (he will cut them for Futaba servos too).
http://www.gbr-jet.com/catalog/index...vc1ei7tdja4j92
This way you can keep the covers as they are. If the wing is too deep you may need to lift the dock by creating a new floor for the dock to sit on. I have some of you need dimensions.


k_sonn 04-22-2012 05:47 PM

RE: Skymaster L-39 Assembly and Scheme Change
 
1 Attachment(s)


I solved the aileron sevo mouning issue by opening the servo bay a little to expose the forward servo mounting tab. I'll make new covers.

Photo 1
With the servos installed it was time to install the control horns. I started with the ailerons and when I cut the slot for the horn I was surprised to see balsa. Well, that didn't last long. Neither the flaps nor the elevators had balsa. Luckliy, the control horns for these are near the root so I cut a section out of each flap and elevator root and made up us balsa blocks to fit.

Photo 2
The blasa blocks were hysoled in place and when that had set, the blocks were slotted and the contro horns were hysiled in place.

Photos 3 - 8
The shaft on the canopy latch is too short and as a result some have lost the canopy in flight. Jack Diaz did a mod that eliminated the nedd for the canopy latch. I used his idea but did the mod differently. The mod started with removing the caonpy latch (Photo 3). I want to fill in the slot so a piece of poly ply was glued in place to give the filler some backing (Photo 4). Next, a 1/8th inch length of aluminum tube was fitted and glued in place and a piece of 4-40 control rod was cut and fitted. The final length of the rod will be determined once the two halves of the fuse are joined.

Photos 9 &amp; 10
I wanted to get some cooling air into the fuse so I installed some NACAducts on the front fuse in the area of the rear equipment tray.

Kirk
</p>

k_sonn 04-22-2012 05:49 PM

RE: Skymaster L-39 Assembly and Scheme Change
 
1 Attachment(s)


Photos 11 -13
I made some new mounting rails for the fan.</p>

Kirk</p>

smchale 04-22-2012 06:10 PM

RE: Skymaster L-39 Assembly and Scheme Change
 
Nice corrections Kirk. Good to see you back in the workshop!

EDFCrazy 04-23-2012 01:56 AM

RE: Skymaster L-39 Assembly and Scheme Change
 
Hey Kirk nice to see this project back on track, and going electric. I think this L-39 will fly really well with that fan. i See C&C models are flying what seems like the slightly larger Jetlegend L39 on electric. Hopefully this will give you an indication of the performance you should see.

here is there link and some videos below, videos below are from this link.
http://www.cmodels.it/modelli_jet/l39%20light.htm

http://www.youtube.com/watch?v=wTjoR...e_gdata_player

http://www.youtube.com/watch?v=8FZI5_ttq54

http://www.youtube.com/watch?v=Q0djV81VCOA

http://www.youtube.com/watch?v=8ruzs...e_gdata_player

k_sonn 04-23-2012 09:28 AM

RE: Skymaster L-39 Assembly and Scheme Change
 

Quote:

ORIGINAL: smchale

Nice corrections Kirk. Good to see you back in the workshop!
Thanks Sean. It is good to be back in the shop http://www.rcuniverse.com/forum/js/f...sn/biggrin.gif

k_sonn 04-23-2012 09:38 AM

RE: Skymaster L-39 Assembly and Scheme Change
 
Hi Simon. It's good to hear from you. Thanks for the video. The fan you see in the pics above is the 1st version of the DS-77. I removed it from the Panther so I could start getting the setup together. I received word from Schubeler last week that the 25 pound thrust DS-77 will be shipped in mid-May. Looking forward to getting that one and installing it in the L-39 http://www.rcuniverse.com/forum/js/f...sn/biggrin.gif

Kirk
Quote:

ORIGINAL: EDFCrazy

Hey Kirk nice to see this project back on track, and going electric. I think this L-39 will fly really well with that fan. i See C&amp;C models are flying what seems like the slightly larger Jetlegend L39 on electric. Hopefully this will give you an indication of the performance you should see.

here is there link and some videos below, videos below are from this link.
http://www.cmodels.it/modelli_jet/l39%20light.htm

http://www.youtube.com/watch?v=wTjoR...e_gdata_player

http://www.youtube.com/watch?v=8FZI5_ttq54

http://www.youtube.com/watch?v=Q0djV81VCOA

http://www.youtube.com/watch?v=8ruzs...e_gdata_player

EDFCrazy 04-23-2012 10:51 AM

RE: Skymaster L-39 Assembly and Scheme Change
 
25 pound thrust DS-77? whats the wattage to achieve that thrust, im guessing he is running 14s? are you planning on open ducting?

k_sonn 04-23-2012 12:48 PM

RE: Skymaster L-39 Assembly and Scheme Change
 

Quote:

ORIGINAL: EDFCrazy

25 pound thrust DS-77? whats the wattage to achieve that thrust, im guessing he is running 14s? are you planning on open ducting?
Hi Simon,

I'm not sure if you are aware that there are 3 models of the 2nd version of the HST fans with thrust ranging between 13 - 25 lbs for the DS-77 HST and 12 - 29 lbs of thrust for the DS-94 HST. The DSM 6745-700 motor powering the 25 lbs thrust DS-77 is also the same motor used in the 29 lbs thrust DS-94 HST. Surprisingly, the amp draw on the new DS-77 is the same as the amp draw on the first version of the fan but the newer version is lighter, uses a 4 pole motor instead of a 2 pole motor,and produces about 5 more pounds of thrust.

To answer your question, the DS-77 DSM 6745-700 HST produces 25 pounds of thrust at 8550 watts on 14 cells (good cells). The DS-94 DSM 6745-700 HST produces 29 pounds of thrust at10,000 watts on 14 cells (good cells).

The L-39 has enough intake area to support the DS-77 but the ducting is very bad with two near 90 degree bends so I will run this setup as open ducted.

Kirk

EDFCrazy 04-24-2012 01:55 AM

RE: Skymaster L-39 Assembly and Scheme Change
 
Thanks Kirk i didnt know that there were these new versions. is there a 77 or 94 that is intended for the 12 cells for roughly 6kw? I wonder why Daniel doesnt supply his new fans, as fan only, like use to as an alternative to his pnp units?

k_sonn 04-24-2012 11:26 AM

RE: Skymaster L-39 Assembly and Scheme Change
 



Quote:

ORIGINAL: EDFCrazy

Thanks Kirk i didnt know that there were these new versions. is there a 77 or 94 that is intended for the 12 cells for roughly 6kw? I wonder why Daniel doesnt supply his new fans, as fan only, like use to as an alternative to his pnp units?
Besides the rotor, one of the main difference between the Schubeler HST and HDT fans is that HST fans are built from the motor up, making the motor an integral part of the fan.</p>

There are a couple of models that run in the 6kw range, but they run on 13 or 14 cells. Below are the numbers. I like the numbers for the DS-77 6740-650. It weighs less than the first version of the DS-77, produces the same amount of thrust, and runs at 45 less amps. If you've seen the video of the 1st version of the DS-77 flying my Ziroli Panther you'll see that it doesn't lack in power.</p>

DS-77 6740-650
Cell Count: 14
Voltage: 51.8
Amp: 119
Watts: 6164
Thrust: 20.7
RPM:28,000</p>

DS-94 6740-650
Cell Count: 13
Voltage: 48.1
Amp: 121
Watts: 5820
Thrust: 21.4
RPM:26,000</p>

DS-94 6740-650
Cell Count: 14
Voltage: 51.8
Amp: 135
Watts: 6993
Thrust: 23.8
RPM:27,000

Kirk</p>

gamalierlozada 04-25-2012 03:59 AM

RE: Skymaster L-39 Assembly and Scheme Change
 
I want to see the final outcome of this build. I ordered a FeiBao L-39 (Edf version) and have been talking to Mike Warren to see which fan version would benefit my application. Also been talking to other respected EDF builder from Down Under (no name mention since this is a Schuebeler thread and I respect that:D) and I will decide between those 2 units. So far the Schuebeler numbers look more appealing but unit weight is also a decisive factor. That's kind the only thing I would love this unit to be a little lighter a 2-2.4 pounds. That would be awesome considering the power it produces. Let's see what is Daniel's input for my application. Good luck with your build!


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