• This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn more.

large scale electronics.

The Hangar

Well-known member
#1
Hi! I am planning on making some large scale planes after seeing so many cool things at FliteFest! I was wondering what electronics would be good for it. I am looking at the Emax GT5335. I have no idea what esc's to buy for it and what props to use with it and what battery size to use. I would probably be using them for giant Guinea Pigs and other twin engine planes. Please let me know what you all think! I've never done any large scale, and all I've done is the stock Flitetest builds, so any advice is appreciated!
 

The Hangar

Well-known member
#3
Thanks! It looks like maybe two 5s lipos in series than? Would an e-flite 80 amp esc be good? If I were to use this set-up in a single motor 3x or 4x FT cub, what would be the weight limit? It says it produces roughly 20 lb of thrust so does that mean if my plane weighed 15 lb I would have enough power to hover? It should still fly even if my plane weighed 40 lb and I got it balanced, right? Thanks so much for your help!
 

The Hangar

Well-known member
#4
Looking further into this, it looks like I would need to get a Castle Creations Phoenix Edge 80HV 50V 80-Amp ESC. It is capable of 12s LiPo. Would it damage the emax motor if I ran it off of 12s but used a less pitched prop like 20x7?
 

b-29er

Active member
#5
Looking further into this, it looks like I would need to get a Castle Creations Phoenix Edge 80HV 50V 80-Amp ESC. It is capable of 12s LiPo. Would it damage the emax motor if I ran it off of 12s but used a less pitched prop like 20x7?
That should not. Less pitch should mean less amp draw, but less pitch speed, which is almost meaningless for a bird like the Guinea anyways
 

ElectriSean

Eternal Student
Mentor
#6
Looking further into this, it looks like I would need to get a Castle Creations Phoenix Edge 80HV 50V 80-Amp ESC. It is capable of 12s LiPo. Would it damage the emax motor if I ran it off of 12s but used a less pitched prop like 20x7?
If you're going to try this, go with the lower kV version. And invest in a watt meter =)
 

Headbang

Well-known member
#7
So a few quick notes from my experiences. When going big try to stick to a battery solution you can use over and over. For a large twin a 60 size or 20cc motor will be in the 1800W to 2200W, most will be 6s. For hovering and 3d you want to keep the wieght under 12-15lbs for those motor sized on a twin (1800Wx2 total divided by 300W/lb for extreme 3d comes to 12lb). Of couse that is extreme power for instant pull out, and just a good place to start when picking motors. For battery size this formula works well for me battery Ah/amp draw*60*2=flight time. Better starting point is figure out an approx wieght of plane with batteries, size motors to match.

The gt5335 looks to be closer to a 40-50cc sized motor, which would suit 3d planes in the 15lb range, or as a twin in the 30lb range. Might be way more motor then you are needing
 

The Hangar

Well-known member
#8
The gt5335 looks to be closer to a 40-50cc sized motor, which would suit 3d planes in the 15lb range, or as a twin in the 30lb range. Might be way more motor then you are needing
You're right. As I look further into this, I am shifting my thinking over to a giant scale cub. I a looking at the GT5325 325kv instead because I could run it on twin 3s batteries or a single 6s. This should give me enough power as long as I keep the build 11-15 lb, right? I would use this with a 19x10 or 19x12 prop. Would the Castle Creations talon 90 brushless ESC be a good choice? the specs seem to match pretty well, and it is a 90 amp esc, right? If I were to do a 3d plane, what would the weight limit be with this motor esc combo?
 

Headbang

Well-known member
#9
You're right. As I look further into this, I am shifting my thinking over to a giant scale cub. I a looking at the GT5325 325kv instead because I could run it on twin 3s batteries or a single 6s. This should give me enough power as long as I keep the build 11-15 lb, right? I would use this with a 19x10 or 19x12 prop. Would the Castle Creations talon 90 brushless ESC be a good choice? the specs seem to match pretty well, and it is a 90 amp esc, right? If I were to do a 3d plane, what would the weight limit be with this motor esc combo?
So this motor is about a 2000W max motor (20-30cc eqv). Sport flying would be 11-13lb, 3D would be 6-8lb. Talon 90 is a good choice, but I would advise against the built in bec in the talon, it has a lower amp rating then a 3d plane would need, and is even a little light for aggressive sport flying. For sport flying the castle bec 2 (14a max) is solid, for 3d the castle bec pro (20a max) is the ticket. If it were me (and it has been, this is the most common size of power setup in my fleet) I would use a castle phoenix edge 100 with a castle bec pro running a gens ace 6s 5000mAh 60c battery and a falcon 19x10 electric wood prop. Sounds perfect for a 90inch super cub!
 

The Hangar

Well-known member
#10
So I should be looking at a 3 meter wing span and keep the build 13lb or less, right? And any tips for large scale builds? I am thinking about permanently attaching the top part of the wing with dihedral into the fuselage and having two wing halves slide and lock into the fuselage/wing. How should I secure the two wing halves? I am planning on running two 5000mah two 25c and two 45 c 3s lipos in series since I already have four of these batteries and want to keep costs to a minimum... Any idea how much flight time I should get with that? Thanks so much for your help!
 
Last edited:

The Hangar

Well-known member
#11
I mentioned I was planning on flying off two 5000mah 25c and 45c 3s lipos. (I have two 25c 3s and two 45c lipos). Are the c ratings too low?
 

Headbang

Well-known member
#12
I mentioned I was planning on flying off two 5000mah 25c and 45c 3s lipos. (I have two 25c 3s and two 45c lipos). Are the c ratings too low?
The 45c should be fine, the 25c might be fine too depending how you fly. You should be in the 6 to 10min flight range depending how you fly.
For build tips go in search of the articles for large builds, look at the giant spitfire and seaduck builds. Balsa and ply Cubs will typically have 2 wings attached to the fuse with a carbon fiber wing tube and a few screws to hold them in. They also have wing struts held with screws (I watch these go together all the time, big Cubs are popular at my home field). In the end there is no wrong way to do anything as long as it works.