Official Nexa 1580mm P-39 Airacobra ARF Thread

[Aros]

P-39 Airacobra 1580mm (62.2") Wingspan - ARF from Nexa - NXA1064-001

The Nexa P-39 Airacobra is a 1580mm (62.2") wingspan ARF replica of the Bell Aircraft fighter used by the United States and Soviet Air Force during WWII. It was one of the principal American fighters in service when the United States entered combat. The P-39 was used by the Soviet Air Force, and enabled individual Soviet pilots to collect the highest number of kills attributed to any U.S. fighter type flown by any air force in any conflict. Constructed with high-quality, precision-cut materials, this aircraft is sure to offer consistent and reliable performance in the air.

The P-39 Airacobra is a .50 size electric or gas option scale series warbird with a 1580mm wingspan, constructed primarily from balsa wood and covered with a fuel-resistant covering. This ARF requires assembly and installation of your choice of servos and power system, and includes flaps, painted pilot, machine guns, antenna and other scale details. The large battery hatch affords ample room for either electric or gas setups. Impress at your flying field with this iconic stunner!

Features:

• Complete Balsa and lite-ply construction for rigidity and durability
• Covered from tip to tail in scale details including weathering, functional flaps, printed simulated panel lines and rivets
• Fiberglass cowling for strength and durability
• The hand-painted pilot is ready for your added cockpit details
• All control surfaces come out of the box pre-hinged and installed for convenience
• Large battery hatch allows for your chosen electric or gas setup

Includes:

• Nexa P-39 Airacobra 1580mm (62.2") Wingspan - ARF
• Assembly instructions with stage photos
• Fixed gear
• Fiberglass motor cowling
• Wheels
• Servo trays
• Engine mounts
• Fuel drop tank
• Fuel tank
• Radiator air scoop
• Decals and all hardware pack

Requires:

• 7 Channel radio - select a minimum 7 channel radio from our Radio Collection
• 7 Channel receiver - select a minimum 7 channel receiver from our Receiver Collection
• Brushless outrunner motor - we recommend the Admiral GP5 4220-770Kv Brushless Motor
• 85 Amp brushless ESC - we recommend the ZTW Mantis G2 85A ESC with 8A SBEC
• 7x micro servos for ailerons, flaps, elevator and rudder - we recommend SEVEN of the Hitec HS-225MG Ball Bearing Metal Gear Mighty Mini Servo
• Electric retracts - we recommend Nexa Rotating Electronic Main Retract (Set of 2)
• 5 Cell 18.5V 4000 mAh LiPo Battery - we recommend the Admiral Pro 4000mAh 5S 18.5V 60C LiPo Battery with EC5 Connector
• Electric propeller - we recommend the APC 13x8 Thin Electric Propeller - Black
• 6 Cell compatible battery charger - select a minimum 6 cell (6S) charger from our Charger Collection

Gas Requires:

• 2 stroke engine - we recommend the NGH GT9 Pro 9cc Two-Stroke Engine
• 2 blade gas propeller - we recommend the APC 11x6 Gas Propeller

Customer Note
Nexa ARF models are constructed out of balsa wood and plywood. These are not foam models. The assembly of balsa wood ARF aircraft requires basic model building skills including the installation of servos, ESC, and motor (or gas engine).

Product Specifications:

AGE LEVEL :14 and up
SKILL LEVEL :intermediate
BUILD TIME :6+ hours

Model Scale	1/9
Wingspan	1580mm / 61.5in
Length	1160mm / 45.5in
Weight	2500g / 88.2oz
CG (Center of Gravity)	82mm from the leading edge of the wing's root
Power System	700Kv Brushless outrunner motor for electric or 2-stroke for gas (required)
Electronic Speed Control	85A (required)
Propeller / EDF	13x8 2-blade for electric or 11x6 gas 2-blade for gas (required)
Servos	7x standard servos for ailerons, flaps, elevator and rudder - HRC32225S
Landing Gear	Fixed (included)
Required Battery	5 Cell 18.5V 4000 mAh LiPo Battery (required)
Required Radio	7+ Channel (required)
Ailerons	Yes
Elevator	Yes
Rudder	Yes
Flaps	Yes
Lights	No
Hinge Type	Nylon
Material	Balsa and light plywood
Skill Level	Intermediate
Build Time	6+ Hours
Recommended Environment	Outdoors

[Evan D]

Airacobra…

[redbarn]

Will there eventually be a set of retracts offered that fit this P-39 and maybe have suspension struts? I'm thinking the rotating retracts mentioned probably aren't for this?

[paulrkytek]

I have had the earlier VQ models version ( same plane ) for a couple of years. with the following spec. :-
VQ airacobra 1400mm ws.( reduced from 1580mm) 2600 to 2700g. WA 34.5dm2 wl /71.5 to 78gms/dm2. cg 80mm back from le. SK3 4240 740kv motor 870wmax 50amp max. with 12x8 jxf prop, Turnigy 3000mah 5s pack, TSS11 dmg on tail and nose, Corona DS939 DMG flaps & Aileron. 5 mins flight time.Throttle curv 30,56,80,94% 1/2t 22a 450w 2/3t 30a 585w 3/4t 37.5a 717w FF 48a 900w at 20.3v iA10Brx Hobby Eagle A3 gyro 3 position switch.gyro on, gyro off, auto balance. It is an easy flying warbird.

Flew well until a couple of months ago when I lost orientation and spun into the ground, broke the wings in 2 destroyed the wing tips, disintegrated the engine cowl, split the fuselage and broke the tail off. Whilst I was stripping out all the part for a use on my VQ Yak 9 I decided to rebuild it as a racing cobra 1400mm wingspan, rebuilt balsa nose and I am part way through the rebuild. I will post photos when finished. Scheme is roughly based on a 1946 yellow and black Cobra 2 Racer https://www.aerialvisuals.ca/Airfram...p?Serial=86812

[paulrkytek]

Just about finished the rebuild, just need to set up servos etc

[Aros]

Nice work!

[paulrkytek]

Will there eventually be a set of retracts offered that fit this P-39 and maybe have suspension struts? I'm thinking the rotating retracts mentioned probably aren't for this?

No rotating, you are better off getting the kit and deciding where to go from there so that you can allow for choice of electric retract, pin sizes, oleos etc to suit yourself. I used substantial mains with 5mm pins, overall length of oleo and wheel 120 to 125mm nose wheel 4mm pin overall length of oleo and wheel 145mm. Look through Motion r.c. retracts, servos and oleos and you should be able to find gear to suit. I set the model on a flat level surface with tail near horizontal and measured down to suit. Manual states flying weight at 2500gms, but you are probably going to be closer to 2900gms with 4000mah 5s setup.

[flyguysc1]

So is it a two sectioned wing ?

[paulrkytek]

So is it a two sectioned wing ?

Port wing and starboard wing with ply wing joiner. Suggest you download and read the instruction manual

[JARied]

Anyone set this up with 6S set up

[paulrkytek]

Anyone set this up with 6S set up

I thought about this for mine. You would have to bear in mind that 6s as opposed to 5 s will probably add an extra 250gms in motor and battery and increase wing loading. Most 6s motors are lower kv larger prop diameter so you would have to check prop ground clearance. I had 5s motor and 5s battery in stock. and decided to stay with that option to keep the wing loading down.. I get 900watts power on my 2700gms model with 12x8 prop. I would personally be looking for around 1200 watts of power min from 6s to offset extra weight and show some performance gain and for most 450 to 500kv 6s motors that means 16x8 prop which will not have ground clearance.. I could have cut down a 16x10 prop to 13 inch and re balanced it but I did not like the idea of cutting 1.5 inch off each tip.

[JARied]

Thank paulrkytek

i mostly have 4s and 6s batteries.
would a 4s set up work.

if I went with 6s I was thinking about using freezing spitfire set up.

[paulrkytek]

Thank paulrkytek

i mostly have 4s and 6s batteries.
would a 4s set up work.

if I went with 6s I was thinking about using freezing spitfire set up.

If you mean Flightline Spitfire 1600 that uses a 5055 390kv motor with a 4 blade 16" prop which will touch the ground on the Airacobra so I do not think that will work.

to use 4s you need to match the motor and prop with the all up flying weight of the plane with everything on board, batteries, servos, motor, esc etc.
Traditionally warbirds fly between 125 and 150 watts per lb or 275 to 330 Watts per kg depending on how much power you need for the flight envelope and how aerobatic you want the model to be. If you are aiming for a target weight of say 2700gms then you are looking at 750 watts to 890 watts . Motion have probably gone for the aerobatic end, hence 5s motor.
Until you receive the kit you cannot start to literally weigh things up. You need to make a shopping list and check out the specs to find the weights of each item, eg, motor, esc, battery, rx, servos, landing gear servos, tyre and wheels , control rods fixings and fittings etc, weigh the airframe and estimate the total weight before committing to buying the necessary parts. Getting a 4s motor like an FMS 3948 760kv motor producing 750 watts should not be a problem. I suspect it will be difficult to get under 2750gms. Sadly you have to do some maths and then decide. . Personally I would go for 5s power, you can always ease your foot off the accelerator and it is better to have power in hand for grass field take offs and getting out of those awkward moments. My rebuilt Cobra ended up at 2700gms take off weight with a 3000mah 5s 375gm lipo, before the rebuild it was 2800gms.

If you click on the recommended motor in post 1 above you will see in the details Admiral GP5 4220-770Kv Brushless Motor it states 2 to 4 s 590 watts power but it also recommends 5S 4000mah lipos in the setup list. ? You would think this cannot be the right motor for this model .

I have now finished my rebuild and I am awaiting good weather to fly ,

[JARied]

Nice job. Thanks for the info will wait for model to arrive and will go from there.

[paulrkytek]

Nice job. Thanks for the info will wait for model to arrive and will go from there.

Have fun, if you are looking to reduce model weight you might consider 17 gm Flightline Spitfire 1600 digital metal gear servos 2.5to 3kg/cm as opposed to the 27gm Hitec servos