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

Help needed on scaled down FT spitfire.

#1
Greetings everyone. Recently I built a scaled-down version of the FT spitfire, with a 22 inches wingspan and a length of around 17 inches.it is roughly equal in size to the mighty minis, though being heavier. I could not find any foamboard in my area so I decided to build the plane from cardboard ( the kind used in shoeboxes ). Although cardboard is inferior to foam board as a building material because of its weight, I tried as best as I could to keep the weight down and ended up with a final ( without battery ) weight of around 210 grams ( 7.4 ounces ). Besides being built out of cardboard and being smaller, it is a fairly good replica of the FT spitfire- with tip undercamber and a dihedral of around 15 degrees. The specs. of my build and the parts I used are as follows ;

Specs:

Wingspan: 22 inches,
Wing Root Chord: 5.5 inches,
Dihedral: 15 degrees,
Wing thickness: 3/8 of an inch
Wing Area: 95 sq inches
Fuselage Length: 17 inches,
Weight without battery: 210 g / 7.4 ounces
All-up Flying Weight: 250 g / 9 ounces
Wing Loading: 13.6 oz./ sq. ft.

Parts:

Motor: Emax Gt2203 1560 kv,
Prop: 7X4 Standard electric propeller,
ESC: 12 Amp rated,
Battery: 800 mAh 2S LiPo,
Servoes: (4) 5 gram servoes.

I have some experience with flying RC planes before, but this is my first scratch build, so I don't exactly know what to expect. The motors in the power packs A and F ( which are geared towards planes of a similar size ) are very similar to this Emax motor, but they both have a higher kv ( 2300 ) and run a smaller prop ( 6X4 ); What effects will these differences make? Another question to all of you experienced flyers is that; will it fly, and how will it handle in the air ( i.e. will it be docile, or fast and difficult to control, will it have enough thrust etc ). Any help at all regarding these issues will be greatly appreciated.
 

BATTLEAXE

Well-known member
#2
Welcome to the forums. Spitfire is a great plane. At 22" wingspan and 210g's it sounds like your build is fairly on par for weight, could be lighter but given what you got it will fly on that aspect alone. Your on the right track. I assume you have flown planes before and probably built your own as well.

It would be a whole lot better if you could post some pics of the build to get a visual of what we are talking about for how it will fly, characteristics and tendencies.

Ideally the higher the Kv, the higher the RPM/volt applied. The F pack is a good motor for power and speed at around 1800Kv. The A pack lacks the torque but has a 2200Kv, higher on the RPM. Your motor sitting at 1560 is lower at the max RPM but it is a good match to the prop you are using. You could even go 6x4 or 7x3 to get a little more efficiency, longer battery life depending on how you fly. What I would suggest though is to up the battery to a 3s. Going from just over 8 volts max power to 12 volts ups your max RPM. Problem solved. Fly the plane on the 12 amp ESC but just to be safe I would go to an 18-20 amp.

Good luck and I will be following this (y)
 
Last edited:
#3
Welcome to the forums. Spitfire is a great plane. At 22" wingspan and 210g's it sounds like your build is fairly on par for weight, could be lighter but given what you got it will fly on that aspect alone. Your on the right track. I assume you have flown planes before and probably built your own as well.

It would be a whole lot better if you could post some pics of the build to get a visual of what we are talking about for how it will fly, characteristics and tendencies.

Ideally the higher the Kv, the higher the RPM/volt applied. The A pack is a good motor for power and speed at around 1800Kv. The A pack lacks the torque but has a 2200Kv, higher on the RPM. Your motor sitting at 1560 is lower at the max RPM but it is a good match to the prop you are using. You could even go 6x4 or 7x3 to get a little more efficiency, longer battery life depending on how you fly. What I would suggest though is to up the battery to a 3s. Going from just over 8 volts max power to 12 volts ups your max RPM. Problem solved. Fly the plane on the 12 amp ESC but just to be safe I would go to an 18-20 amp.

Good luck and I will be following this (y)
Thanks a lot for the help. I will be posting pictures soon