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Old Jan 14, 2012, 12:49 AM
I need a bigger garage...
ajreynolds's Avatar
USA, CA, San Diego
Joined Mar 2005
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Sapac/Global Fly foam L-39

Looks like I'm a bit late to the game as I've just picked up my first Sapac planea, a Sapac/Global Fly L-39 from Cermark at the AMA show. It looks nice, with the 70mm fan, motor, ESC, servos and includes retracts and flaps. I've read good things about Sapac, so I hope this model lives up to the name. I've been flying for several years, but this is only my second EDF (first was a GWS A-4 which I went overboard with and came out way too heavy, but was still fun), so I was hoping to ask a few EDF noob questions. I posted these in the foamy EDF forum, but haven't received any response at all. I've found a few videos online about the L-39, but no threads anywhere. This one has a 35" wingspan and 44.8" length (http://www.cermark.com/products/Sapa...rsion-EDF.html) I have come across a thread for a different Sapac foam L-39, but it looks like it was slightly smaller and some of the details are different.

Has anyone else had this plane? Anyone know of any threads on this? Any thoughts or tips?

A couple of questions I have just from looking through the kit are about the fan. Are the fans in these kits balanced, or should I try to get it out of the fuselage to balance it? I can't figure out how to get the fan out without cutting the foam. It's got a tailcone on it, which my A-4 didn't have. They must have put the fan in place and then stuck the tailcone on through the exhaust. Does the tailcone usually just pull off? If so, I'll have to figure out how to get in there to get a grip if I want to take the fan out.

Also, on my A-4 the fan had tabs on the side for mounting to the fuselage. This fan doesn't have tabs. Will I need to glue it into the fuselage or just let it float free and rely on the part that goes over it to hold it in place?

Thanks,

Andy
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Old Feb 24, 2012, 11:54 AM
Diverted by planks
tracknoob's Avatar
South Florida
Joined Dec 2010
4,727 Posts
Andy,

Just bought the exact same plane, and have the exact same questions that you did!

I see no one replied, so I hope you found the answers, and I guess I'll try to muddle my own way through too. My only other EDF is a F9F 50mm, took a long time for me to initially figure it out, but now I'm comfortable with it, so I hope this one is a good second ship!

Cheers!
TN
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Old Feb 24, 2012, 05:18 PM
I need a bigger garage...
ajreynolds's Avatar
USA, CA, San Diego
Joined Mar 2005
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I did find a thread which seems like it's for an earlier revision of this plane, you might find some useful info there. The thread is at http://www.rcgroups.com/forums/showthread.php?t=1015882

I'm getting close on mine. I hope to paint it this weekend. Grey/blue isn't a very good combination for visibility... Here are a few things I've discovered in building this plane so far:

I ended up cutting a bit of foam out in the slot behind the fan so I could pull the fan out. I cut it carefully so I could glue it back in afterwards. After getting the fan out, I pulled off the cone on the back. If figure it will give the motor a little better cooling on hot days. The cone was glued on with a little bit of CA on one side, but it popped off cleanly. Looking at the back of the motor, I see a couple of dots where it looks like someone drilled a little into the back of the bell of the motor. I think that was done in a balancing process, so I decided not to take the fan apart to balance. When I'm ready, I plan to glue the fan in with a little hot glue.

The linkages on this plane have tons of slop. The holes in the servo arms and control horns are way too big for the wires and clevises included. I ended up throwing all of them away and getting some new ones at the hobby shop.

The arm on my rudder servo wasn't centered correctly before gluing in, so I couldn't get proper travel both ways. I had to pull the servo out (it's hot glued in) to get the arm off. Once centered, put the arm back on so it's at 90 degrees to the pushrod, not 90 degrees to the side of the servo, since the pushrod goes at an angle back to the rudder.

Give all of the servos a good tug to make sure they are in securely. Some of mine weren't glued in well and need to be reglued.

Check your retracts to make sure they move smoothly. Mine had a definite click and needed a bit of force when locking at each end. I took them apart and did a little sanding on some of the parts so they move really smoothly.

I also replaced move the nose retract pushrod to the outmost hole of the servo arm and repositioned the arm on the servo so I could get it retracting properly. I haven't done it yet, but I plan to replace the wire in the nose retract since the wire seems too small and makes the nose leg wobbly.

I also didn't like how the wing mounted. When screwed on it was a bit wiggly, so I added some alignment pins and a bit of thin ply to hold it. I found this idea on the thread I mentioned earlier on page 7, post 101.

Andy
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Old Feb 24, 2012, 09:19 PM
Diverted by planks
tracknoob's Avatar
South Florida
Joined Dec 2010
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Quote:
Originally Posted by ajreynolds View Post
I did find a thread which seems like it's for an earlier revision of this plane, you might find some useful info there.


Here are a few things I've discovered in building this plane so far:
...

Andy
Wow, great info!

Yup, I stumbled across the larger thread earlier today, so I posted a few pics over there of my plane as I am assembling it.

I also discovered a lot of the same shortcomings you mention, and that are discussed on the larger thread. I was going to take the cone off the back, but then I figured 'meh', why not give it a shot and see what happen as-is and you can always remove it later....

I want this plane to be a success, and at the same time, I don't want to sink a ton of money or time into making it super-refined, since it was all of $120 shipped to my door, and will be essentially my EDF trainer...

I did spend some time working with the gear, and adjusting it mechanically, then my radio travel limits to try to get it smooth, consistent, but not leave pressure on the servo at rest. It seems okay, but even after a lot of jiggling and fiddling, still not perfect, it growls a bit when the gear are up, but when I release the rods, there is no major movement to release pressure (as there was before I got the travels right), instead jt seems to be just the geometry is not ideal on this setup.

If the gear gets touchy or breaks as it seems to do for a lot of folks, I think I'll either just 'upgrade' to HK ( never thought I'd say that phrase!), or make it a fixed gear set-up.

The one part I don't have in my kitbag for this thing that I wish I had is an 80 amp ESC. I took a peek around, and heck, most decent ESCs are the price of this plane! So, with running a separate BEC, and checking the static amps fist to be sure I am okay, I think I will then just run what's already in there, and if I ever have to dead stick it due to ESC failure, I guess I'll do that. It's a shame that they so underspec these things that here I am with the right capacity and cells of battery, but I'm worried about it failing just because my C rating is higher than the cheap battery they combine in the RTF package.


Thanks again for the reply!
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