Official Freewing 80mm EDF L-39 Albatros Thread

[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

[sam51401]

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

[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 ?

[JLambCWU]

Stills from the video

[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]

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.

[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]

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 :(. )

[Evan D]

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

[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 ?

[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]

Thanks , I was thinking about a small amounts .

[AceMigKiller]

I use expo of zero amounts on every model.

Expo is a tool that can be used to great advantage. On a model like the L-39, a light value (say, 10-15% on elevator and maybe 20% ailerons) can help tame it at higher speeds.
However, I see alot of people over-using expo and in an effort to make a smoother reacting plane cause over-control issues.

Play around with light values and see if you like it. Increase/Decrease as you like!

[Evan D]

I use expo of various amounts on every model.

[Joehockey]

Are you guys using Expo on this model ?

[xviper]

Thanks xviper 😜. I did go to the spare parts page but didn't see the L39 listed under the 4.1mm retract in the list of planes for which the retract is used for so I was not sure whether it was the ccorrect retract. See screenshot.

That's because that list is on the L-39 part's page. You know it's for the L-39 because you went there, so they're not going to list it again. Do like what DCORSAIR said. Bye the whole thing. The shipping is going to be almost as much as the part anyway.

[DCORSAIR]

Thanks xviper 😜. I did go to the spare parts page but didn't see the L39 listed under the 4.1mm retract in the list of planes for which the retract is used for so I was not sure whether it was the ccorrect retract. See screenshot.

I would buy the whole thing myself, its just a few dollars more to buy the whole retract unit, this way you can have a spare strut and parts, there are micro switches in them that do go out as well, just a thought.

[Roger Rabbit]

Thanks xviper 😜. I did go to the spare parts page but didn't see the L39 listed under the 4.1mm retract in the list of planes for which the retract is used for so I was not sure whether it was the ccorrect retract. See screenshot.

[xviper]

Hi, I am please looking for the correct nose gear retract part number to place an order from Motion RC.
My L39 Nose gear from day one would not fully retract about every third or so cycle. I have done 15 flights (all with smooth landings) and noticed a lot of play on the nose gear and pulled the retract Today and found the casing was cracked causing play on the trunion. Very nice plane but the retract quality is questionable. My Avanti has close to 100 flights wit absolutely no issues...

All you had to do was to go to the product webpage and look it up on the spare parts section for this plane. You can get just the retract ................................
https://www.motionrc.com/products/fr...m-shaft-type-b
Or you can get the whole assembly, with strut and tire and steering tiller arm:
https://www.motionrc.com/products/fr...e-landing-gear
You don't need a part number. Just go to that part page and add it to cart.

[Roger Rabbit]

Hi, I am please looking for the correct nose gear retract part number to place an order from Motion RC.
My L39 Nose gear from day one would not fully retract about every third or so cycle. I have done 15 flights (all with smooth landings) and noticed a lot of play on the nose gear and pulled the retract Today and found the casing was cracked causing play on the trunion. Very nice plane but the retract quality is questionable. My Avanti has close to 100 flights wit absolutely no issues...