RE: Great Planes L-39

RE: Great Planes L-39
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RE: Great Planes L-39 - 6/17/2008 9:03:39 PM

gr8taz nitro

Posts: 100
Joined: 6/18/2003
From: Joplin, MO, USA
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That motor will work fine on a 4 cell. Somewhere else in here I posted the claimed GP specs and they tested the hyperflow system with that motor on a 4 cell lipo. Their specs are pretty close for a change. I'm using the 24-33-4875 and finally got it on a meter. With a TP2200 3 cell it spiked to 36 amps and then settled in around 33 amps with close to 340 watts. According to the meter it sucked down 800 mah in about 45 seconds, although I don't know how accurate that reading was.

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Post #: 101

RE: Great Planes L-39 - 6/17/2008 9:43:25 PM

Teenage Pilot 13

Posts: 81
Joined: 12/8/2007
From: Somewhere cold & windy, MN, USA
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I've been reading around here and a question popped into my head: What's faster, the L-39 or the Synapse? (Anyone who has both?) I'm thinking that the L-39 would have been a better option for me considering my inexperience with jets and my too-fast setup I put on my Synapse the first time out

. I may go for an L-39 if the Synapse doesn't pull through my last (and most spectacular

) crash.

Also, I'm officially terrified of anything that has only 26" of wings and the ability to cover 120' in (no exaggeration) 1.25 seconds

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Post #: 102

RE: Great Planes L-39 - 6/18/2008 12:26:51 AM

animal acker

Posts: 143
Joined: 2/29/2008
From: st. louis, MO, USA
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Hey dslusrc: I like the video, but have a question. I have a diablo with a dons wicked 5400 also and an xf edf, what is it that you like about the 4000kv instead of the 54oo I know you can use a 4cell on either so I was wondering what your reason was?

Also, To anyone who might know, I am using a thunderbird 54 esc from castle, and it says use with 3cell. Why is that? It can take more power than the pentium that some people are using but not the extra cell. Strange.

Paul: I finally got a wattmeter. and Im pretty sure my diablo is the fastest in the land as far as flying turds are concerned. It's fast but not as fast as the video that I just saw. WOW!

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Post #: 103

RE: Great Planes L-39 - 6/18/2008 1:21:55 AM

dslusarc

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Joined: 6/22/2003
From: Willoughby, OH, USA
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I used the 4000 as the stock fan is a 5 blade fan and has fairy high pitch so it needs some power (more trhan the XF fan). The 4000 in the Hyperflow fan is about 450 watts on 4S. The 4800 in that fan on 4S is about 550watts. The 5400 would be even higher in that fan. I did fly the 5400 on 3S in the stock fan, it was pretty fast (almost as fast as in the video) but was pulling about 380 watts. I am now going for more speed by usign an Alfa 5 blade fan instead.

Don

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Post #: 104

RE: Great Planes L-39 - 6/18/2008 6:57:58 PM

paul daniel

Posts: 69
Joined: 9/16/2006
From: Pewaukee, WI, ALBANIA
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AA: The Diablo is still a flying turd! The L-39 was faster out of the box. The only thing I'm getting with mine is a little bit of a tail wag once in a while like there's not enough surface area in the vertical fin. My Twister tracks like it's on rails.
Paul

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Post #: 105

RE: Great Planes L-39 - 6/19/2008 2:53:12 AM

bobripley

Posts: 68
Joined: 10/9/2002
From: Hurricane, WV, USA
Status: offline

Hello All,

I bought my L-39 before reading the posts in this forum. Frankly, I'm not sure if I would have made the purchase after reading what a lot of folks had done to get the performance they were looking for. It seemed like you had to dump a bunch more money into the project to get it to fly.

I built mine according to the recommendation on the box (25 Amp speed controller) and used the supplied in runner motor. The only thing that I did was to up the capacity of the battery to a 2200 mA 3 cell. The test flight was this evening and I am happy to report that the plane flew fine. A firm under hand launch and L-39 was up and a way. She flew straight and true with precise control authority. It was fast enough for my taste. Certainly no pylon racer but there was no mistaking that it flew and sounded like a jet. Flight time was about seven minutes until I decided to land. She glides forever. Post flight, both the battery and speed controller were warm to the touch. I’m happy.
It is a good looking fine flying model right out of the box and for not a lot of money.

Rip

< Message edited by bobripley -- 6/19/2008 2:55:26 AM >

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Post #: 106

RE: Great Planes L-39 - 6/19/2008 3:24:30 AM

crashcrash

Posts: 3490
Joined: 11/23/2006
From: St Louis, MI, USA
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quote:

ORIGINAL: bobripley

Hello All,

I bought my L-39 before reading the posts in this forum. Frankly, I'm not sure if I would have made the purchase after reading what a lot of folks had done to get the performance they were looking for. It seemed like you had to dump a bunch more money into the project to get it to fly.

I built mine according to the recommendation on the box (25 Amp speed controller) and used the supplied in runner motor. The only thing that I did was to up the capacity of the battery to a 2200 mA 3 cell. The test flight was this evening and I am happy to report that the plane flew fine. A firm under hand launch and L-39 was up and a way. She flew straight and true with precise control authority. It was fast enough for my taste. Certainly no pylon racer but there was no mistaking that it flew and sounded like a jet. Flight time was about seven minutes until I decided to land. She glides forever. Post flight, both the battery and speed controller were warm to the touch. I’m happy.
It is a good looking fine flying model right out of the box and for not a lot of money.

Rip

Nice report. I've been following this thread for a while and I'm considering getting one but I was a little reluctant to purchase because of the horror stories on this bird. I get a warm and fuzzy from your report though....I might just get one soon then. Thanks!

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Post #: 107

RE: Great Planes L-39 - 6/19/2008 3:29:02 AM

animal acker

Posts: 143
Joined: 2/29/2008
From: st. louis, MO, USA
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Paul: Why do you think the diablo is so slow even with all the upgrades when compared to the L-39? I dont doubt you from what I've seen thus far the L-39 is hands down way better, but if you could take a moment and try to think about what it is that is so different in the two planes. Is it the weight difference is there an aerodynamic\drag difference? I am curious. Also I am ready, I will get an L-39, it is the next logical step for me. Are they still on back order? And about the servos, I still have my servos that came with my dx6, can those be used? if not what are generally a good fit?

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Post #: 108

RE: Great Planes L-39 - 6/19/2008 3:58:05 AM

animal acker

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Joined: 2/29/2008
From: st. louis, MO, USA
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OK, I just ordered one, late june is expected eta. I cant wait!

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Post #: 109

RE: Great Planes L-39 - 6/19/2008 4:05:50 AM

dslusarc

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From: Willoughby, OH, USA
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Modified the L-39 and installed the Alfa 5 blade fan instead of stock fan. Here is some video from my head cam I posted on Youtube. After I brought it home I made the proper size exit nozzle and will fly again hopefully tomorrow, it should add a few more mph.

http://youtube.com/watch?v=JjYwxHPOBKM

Don

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Post #: 110

RE: Great Planes L-39 - 6/19/2008 4:09:32 PM

Gordito Volador

Posts: 565
Joined: 7/1/2003
From: Ruskin, FL, USA
Status: offline

Don,

That bad boy really moves! Please let us know about the thrust tube results.

Regards, Bill

< Message edited by Gordito Volador -- 6/19/2008 4:29:19 PM >

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Post #: 111

RE: Great Planes L-39 - 6/19/2008 5:05:26 PM

crashcrash

Posts: 3490
Joined: 11/23/2006
From: St Louis, MI, USA
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quote:

ORIGINAL: Gordito Volador

Don,

That bad boy really moves! Please let us know about the thrust tube results.

Regards, Bill

What really amazes me is by design....these things should EXPLODE going that fast, yet they do not...WOW!

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RTF is a mis-nomer...no plane or heli is RTF

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Post #: 112

RE: Great Planes L-39 - 6/19/2008 5:59:52 PM

paul daniel

Posts: 69
Joined: 9/16/2006
From: Pewaukee, WI, ALBANIA
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AA: The Diablo and L-39 have only two things in common. One, they share the same fan unit and two they are both EDFs. Outside of that, it's night and day. The Diablo used a brushed motor and in the trainer mode has all kinds of dihedral in the wing. It was designed to be an inexpensive trainer. Looked cool but nothing more than a trainer. Adding the short wings and the twin fan unit made it nothing more than a flying brick. It never could go much faster although you guys sure did try. I'll give you that. Now with the L-39, right out of the box you have a jet that flies pretty well with no mods and screams with what some of the guys are doing to it. My only slight rub on it is that I think it needs a bigger fin since mine seems to tail wag from time to time. Doesn't track as well as my Twister but still a lot of fun.
Paul

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Post #: 113

RE: Great Planes L-39 - 6/20/2008 1:30:58 AM

rcmiket

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Joined: 12/11/2003
From: El Paso, TX, USA
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Quick question without wading though the tread. The LHS is offering me the L-39 90 bucks out the door. I have tons of batteries and the stuff to get it flying (from my helicopters and other electrics stuff I fly). I don't