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Old Sep 21, 2011, 12:20 PM
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Irvine, Calif USA
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Hopefully the CMP L-39 will be a bit lighter ...

The wing is slightly bigger in area, while the overall weight is claimed to be about the same, which explains the reduced wingloading.

It certainly seems (as all L-39's) a good candidate for EDF, with the batteries out of the way in the front

Also, there's a ton of very colorful L-39 schemes out there.

http://cmpairplane.com/

http://www.chinapro09.com/oem.html

L-39 Albatros EDF China Pro 09 CMP CMPro (1 min 14 sec)



.
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Old Sep 21, 2011, 06:50 PM
Another one on the way...
ysolomon's Avatar
Plano, Texas
Joined Feb 2009
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Quote:
Originally Posted by ozgur View Post
Nice work Yoram,

Yes, its really good if you share the templates of fences.

Ozgur

Sorry it took me so long. I actually replied once, but somehow the message was rejected... So, here goes.

First of all--there wasn't too much science involved, and keep in mind that my T-45 hasn't flown yet, so you can implement what I did at your own risk...

I really didn't use a template. I just took a strip of Fliteskin, 8mm wide, and cut it to 8mm x 8mm squares. Then I cut two of those corners in a 45 degree angle, so I essentially got a 4mm x 8mm fence, with a triangle (or trapezoid, if you don't do 45 degrees) below it.

The slots I made in the wings were exactly where they are marked on the wings (8 on each wing), but with an orientation of the flight direction (the markings on the wing are in an angle that seemed too much for me. X30Pilot told me I should have given "some" angle, but mine are completely aligned with the flight direction. I used a hobby knife to cut the slots. Make sure the knife is sharp, or you will apply too much pressure and cut too much (speaking from experience...)

I inserted the fences into the slots, triangle/trapezoid first, until I had the 8mm x 4mm fence on top. Then I dripped a single drop of thin CA on each side of each fence. The glue went into the slot and made a very good contact.

Once the CA dried up--I painted the fences with red (12) and white (4) acrylic paint on both sides, and that was that. It feels pretty strong to me. I never flew this plane without the fences, so I can't tell you if I feel any difference. It's just that this plane is heavy for those small wings, and I hear that it has a strong tendency to tip stall. I crashed my SAPAC T-45 before, and I would like to avoid crashing this one...

I hope this helps.
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Old Oct 09, 2011, 01:10 PM
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I flew the T-45 yesterday and did a few circuits with landing approaches to test the glide.

I think there's a slight thrust incidence problem.

I was flying the downwind leg on full power and it would climb slightly. Then I was doing a nice wide turn followed by a low power (almost idle) upwind pass and the thing would loose altitude rapidly, far more than I would have expected given the speed. Ok the T-45 is a bit draggy, but not that much ...

To me it looks like the tailpipe is pointing up too much, which would require some down elevator compensation on full throttle. On the glide then it drops more than it should, due to the inherent down trim.

Some of it could be taken out by an elevator-to-throttle mix, but I am going to try a mechanical (thrust angle) adjustment first which I prefer.

This will require some dremeling and shimming of the tailpipe so it points down a bit more. Will test it soon ...
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Old Oct 09, 2011, 04:51 PM
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United States, CA, Marina
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I just flew mines on the cc ice 100, no problems. im not downing HK. but both esc from there gave out on me, DLUX 100a and the 90-100a HK brand.
on landing one of my landing gear didn't come down, I had to belly land it.
the belly pan was just scraped up a bit. everything else was good, I slowed it down as much as i could before it wanted to snap, '
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Old Oct 11, 2011, 05:10 PM
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Irvine, Calif USA
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Well those two esc's are a bit marginal, come on, $20 and $30 ... you need to spend a bit more money A good esc is a good investment.

Look at the K-Force one, they are made by Hobbywing (an ESC company!) and are good quality ... just a suggestion. Or the Brain ones as an altenative, those are made by HiFei (also an ESC company!).

HK just re-brands and distributes them ... who knows who makes the $30 ones, maybe a guy and his sister one floor down from HK's offices

Sometimes when the gear hangs it means the strut got bent on a previous landing, or on takeoff if there's bumps in the grass.
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Old Oct 11, 2011, 06:49 PM
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United States, CA, Marina
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You are so right Herb. Those esc were cheap. So I finally went with my friends recommendations and bought the ice 100. And it flew nice.
The gear problem was dirt inside of it. I opened it up cleaned the parts, oiled them back and they work perfect.
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Old Oct 11, 2011, 07:02 PM
"My grandma wants to fly jets"
heychas's Avatar
Richmond, VA
Joined Feb 2008
471 Posts
Stick and Rudder

[QUOTE=Herb;19545953]
on full power and it would climb slightly... and low power (almost idle) and the thing would loose altitude rapidly[QUOTE]

Herb, I know you know a lot about aerodynamics! Think about what you said above
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Old Oct 11, 2011, 10:27 PM
Guarantee at least one landing
Burdo's Avatar
Australia, QLD, Mooloolaba
Joined Aug 2007
316 Posts
Quote:
Originally Posted by Mannyman535 View Post
I just flew mines on the cc ice 100, no problems. im not downing HK. but both esc from there gave out on me, DLUX 100a and the 90-100a HK brand.
on landing one of my landing gear didn't come down, I had to belly land it.
the belly pan was just scraped up a bit. everything else was good, I slowed it down as much as i could before it wanted to snap, '
Both those ESC's are definately at the lower end of HK ESC's list. I would have gone with the Sentilon 100A HV, or the K-Force 120A.

I'm going to try an ESC from ExtremeRC, one of his Lightning brand. A mate at my field uses them and he swears by them. I've got a 40amp of his and push it to its limits. Never missed a beat and the prices are pretty good.
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Old Oct 11, 2011, 10:32 PM
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Well what I meant to say when I was looking at the power off "glide" last weekend it looks like it drops like it has down-trim, waaay too fast imo.

I was feeding what looked to me like excessive up elevator to slow down the drop.

So I suspect that when trimmed out for level flight at full power, you get a good dose of downtrim for power off.

I am going to change the thrust angle a bit and see what it does. It's not the first edf that needs some thrust angle adjustment.
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Old Oct 12, 2011, 11:57 AM
Fill'er Up!
mattyhawk's Avatar
Oxnard, Ca
Joined Oct 2008
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Quote:
Originally Posted by Burdo View Post
Both those ESC's are definately at the lower end of HK ESC's list. I would have gone with the Sentilon 100A HV, or the K-Force 120A.
Sorry to jump in here, been following the thread for a while, though I would add a perspective on the ESC's mentioned as I have experience with almost all the cheap ones mentioned.

The Super Simple 90-100A (rebranded suppo) esc is fine to use up to 7S, very solid unit.

An example is the Sentilon 100A HV, piece of junk. Sync issues on high pole motors and burns up on anything on 12S and some 10S applications with higher pole motors. Does work ok on low pole motors like what would be used in an EDF application though.

Now that TURNIGY K-Force 120A-HV, oh baby what an amazing esc for the price, works awesome and can't go wrong using it, and the price is still good.

BTW: loving this CMP T-45, I would hope to get hooked up with one soon, but the L-39 coming from CMP might catch my fancy first. Thanks for all the great info!
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Old Oct 12, 2011, 12:24 PM
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Quote:
Originally Posted by mattyhawk View Post
... An example is the Sentilon 100A HV, piece of junk. Sync issues on high pole motors and burns up on anything on 12S and some 10S applications with higher pole motors. Does work ok on low pole motors like what would be used in an EDF application though. ...
I have a Sentilon 100A HV (maybe a year and a half old) and it has worked fine for me for the EDF use I have done: Runs on 9S 4000's with a 4-pole Neu 1515-1.5Y motor in a Wemotec Midifan 90mm. Never a glitch, very good value.

The above Sentilon is possibly an earlier Hobbywing/K esc model. The K-Force 120A HV looks like it's update.

Make sure you set LOW 8kHz switching freq. on 4-pole inrunner motors like HET and Neu, and LOW timing ...

I guess the Sentilon is at it's limits on 12S and higher pole motors ... would probaly be just fine in the T-45 on 8S or so ?

.
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Old Oct 14, 2011, 12:50 AM
Fill'er Up!
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Oxnard, Ca
Joined Oct 2008
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Quote:
Originally Posted by Herb View Post
I have a Sentilon 100A HV (maybe a year and a half old) and it has worked fine for me for the EDF use I have done: Runs on 9S 4000's with a 4-pole Neu 1515-1.5Y motor in a Wemotec Midifan 90mm. Never a glitch, very good value.

The above Sentilon is possibly an earlier Hobbywing/K esc model. The K-Force 120A HV looks like it's update.

Make sure you set LOW 8kHz switching freq. on 4-pole inrunner motors like HET and Neu, and LOW timing ...

I guess the Sentilon is at it's limits on 12S and higher pole motors ... would probaly be just fine in the T-45 on 8S or so ?

.
Yeah, I have the Sentilion working for me also, but only on 8S in a Turnigy 50-65 380kv (14 pole). It works pretty well in the plane its on. I wouldn't try it any higher in cell count on that motor, I have read too many people with sync issues with it and I have to run mine on high timing to run right. I would bet it would do fine on a 2-4 pole motor.
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Old Oct 22, 2011, 01:19 PM
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I got two of these and they look pretty good, they are made by Hifei

http://www.hobbyking.com/hobbyking/s...hless_ESC.html

which is a reasonably good ESC brand:

http://www.hifei.com/en/index.asp

Of course if you stick with 6S you can get much cheaper esc's which might be the way to go on the T-45 ...

I have this one as well, and it's a Hobbywing product

http://www.hobbyking.com/hobbyking/s...hless_ESC.html

My guess is that Hobbywing (which also makes the K-Force series)

http://www.hobbywing.com/english/

is among the best ESC manufacturers in China.
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Old Oct 23, 2011, 02:07 PM
Another one on the way...
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Plano, Texas
Joined Feb 2009
2,358 Posts
Fort Worth 2011 Air Show

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Old Oct 24, 2011, 07:59 PM
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Irvine, Calif USA
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Those are very nice pictures ! Thanks for sharing

Now get your T-45 finished up and ready for the maiden ...
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