Official Freewing 80mm EDF L-39 Albatros Thread

[Joehockey]

Thanks , I was thinking about a small amounts .

[JeremySean]

https://www.youtube.com/watch?v=Gv1NYL9g4K8 This is the flight... this is on a 4000mah which I didn't like the way it flew compared to the 5800mah. This plane is light on its wings and creates a lot of lift compared to other 80mm's.

[Joehockey]

Guys , on 6s5000, anyone locked in a suggested CG . My Graphene packs from Hobby King are heavy.
Also CG calculated with gear up and right side up correct ?

[Evan D]

CG is CG, battery doesn’t change it. I do gear down.

[JLambCWU]

A very hot and gusty 93°, but an amazing day to fly the L-39.
Put up 5 sorties on the Albatros, and a total of 22 flights for the day.

The new 80mm inrunner has this bird doing over 130mph across the ground here in the mountains of Utah.
(Couldn’t get the videoclip to upload :(. )

[AceMigKiller]

That new inrunner setup is way awesome, especially for us up at altitude.
I'm in the middle of swapping all my 80mm stuff over to it.

[JLambCWU]

The fantastic 80mm L-39 from Freewing and MotionRC. Very gusty and hot day but still getting low like we do in UT. This jet is tracking over the ground at 130mph+ with the stock inrunner.
Low inverted pass dedicated to camera girl that couldn’t be there for the flying.

[Joehockey]

Hi Evan
yes I know all about CG and typically use 25 % of Mac.
However this model seems a little tedious on my stand.
Curious on why wheels down when the front gear retracts aft and would impact CG ?

[JLambCWU]

Stills from the video

[Evan D]

A percentage of chord is dangerous as many airplanes have fuselages or other appendages that affect center of lift.

On a new release I’ll start at the book site and adjust from there. If others have experience I’ll listen and decide if I trust their opinions.

i alway balance gear down. It’s leftover from glow/ gas days when you balanced tank empty unless the tank was behind the CG. That way I’m balancing for the most critical phase of flight, landing. But that’s my way and other do it their way. My advice is to make your own decision and be consistent. And understand your methods limitations.

Let me add that after building and a flight check to establish where I like a planes balance, checking a balance is just to make sure where a specific balance is at when putting in batteries. It’s much easier to do a quick check with the plane on its wheels.

Hi Evan
yes I know all about CG and typically use 25 % of Mac.
However this model seems a little tedious on my stand.
Curious on why wheels down when the front gear retracts aft and would impact CG ?

[sam51401]

If that still of the inverted pass doesn't make Motions page, it will be a real injustice. That is down right awesome.

[Joehockey]

Thanks Evan , I figured it out with the use of MAC.
MAC is never a dangerous guess, its an aeronautical formula used on real aircraft that works wonders on model aircraft.
I have always used 25% of Mac to test stated CG on any model. 25% of Mac will never ever cause a model to crash from the wrong CG. The biggest challenge with the L39 is the swept wing but i did the math and I am all set.

JLam —great pics and video !


Center of Gravity Calculator

www.gsal.org › tools › cgcalc › centerofgravitycalculator
(for normal planes it should be between 30-33%, flying wings will be 20-25%) ... Simple calculator for determining The CG distance from Leading edge at the ... * Note: A 25% of MAC is generally accepted as a good starting point for the CG

[JeremySean]

Cockpit view, this thing does well over 100mph...Very gusty day!! 2:30 seconds in the video is the speed run!!!

[DCORSAIR]

Jlamb, nice pics, and I see that inverted pic made it on the MRC page....

[Mizer67]

Does anyone have a shot of how the spring-loaded nose gear door works?

Wanting to know if it's something I can retrofit into another plane.

[xviper]

Putting "nose retract" into this thread's search gives you this:

https://www.hobbysquawk.com/forum/rc-airplanes/rc-military-jets/149827-official-freewing-80mm-edf-l-39-albatros-thread?p=221161#post221161

It's a mechanical system. The gear strut pushes down on a bar, which is connected to the door via a push rod. The bar is held by a spring, which pulls up on the bar, allowing the door to open when the strut no longer pushes on it.

[Mizer67]

Putting "nose retract" into this thread's search gives you this:

https://www.hobbysquawk.com/forum/rc-airplanes/rc-military-jets/149827-official-freewing-80mm-edf-l-39-albatros-thread?p=221161#post221161

It's a mechanical system. The gear strut pushes down on a bar, which is connected to the door via a push rod. The bar is held by a spring, which pulls up on the bar, allowing the door to open when the strut no longer pushes on it.

Thanks. I'm leery of any system that relies on this FW nose retract hitting resistance and still closing reliably, but may still give it a shot.

[xviper]

Thanks. I'm leery of any system that relies on this FW nose retract hitting resistance and still closing reliably, but may still give it a shot.

You are right. Mechanisms of this nature can misalign over time or become hard to push and cause a gear jam. I just finished putting in a new nose retract on my FMS Tigercat thinking the old one was too weak. Had to wait nearly 3 months for the part to arrive. Nobody in N. America had stock. After some time and effort to put it in, the problem still exists. The problem being that the retract simply does not have sufficient strength to push on the door mechanism to fully close the door and the strut hangs down a bit. I've given up and will just fly the plane as is since it doesn't seem to affect the retract's ability to open and close, just not its full close limit. As it turns out, this is a common problem with most FMS 7F7's. RC Informer did an extensive modification of the mechanism so make it work better. I think it still has limitations. The Flightline F7F has a much better mechanism.
Having said that, I must admit that the one of the L-39 has never been a problem. However, the L-39 has a much shorter strut than the F7F and I believe that this type of mechanism is not well suited to retracts with long struts. The leverage (mechanical advantage) is simply not there. They require very strong retracts, ones meant for a much larger plane with larger gear.

[400driver]

Just flown my first flight with the L39 on some 7 year old packs with a humble 25C rating. Its time to bump up to 45C or higher but it seems most of Hobbyking is out of good batteries.
The Graphene 6S 5000mah one are available but like the Admiral carbons are around 900 grams each, is that still OK for this jet? I'm hoping to get the Mig 29 so that battery seems a good fit. The Admirals are quite a bit more money here in Europe than in the States.
Any thoughts greatfully received.
Mark

[cashmoneybrother]

Left side landing light wont turn on at all and nav light only turns on when gear is up. Right side landing light is on all the time but gets dimmer when gear is up. If I disconnect the left side then the right side works as intended. Please help!!!