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Need for Speed: how to make plane faster.

#1
I have an FT Racer that is built with the power pack "C" which comes with the (EMAX GT2215/10 1100kV Brushless Motor)
Onboard is the flite test 35amp ESC and I run an 8x6 prop.
The FT racer weighs in at about 500g and with a 2200mah batt (174g), it's AUW is about 700g.

I would like it to go faster!!!!... not insanely faster but just faster.... a little more speed would be nice.

What motor upgrade is possible that allows me to continue to use the same ESC.

I'm guessing if I can move up in Kv that will allow me to turn prop faster but I imagine that requires more ESC and/or more Battery.


Suggestions welcome... Thanks!
 

BATTLEAXE

Well-known member
#3
You could go with a 4s, that would be ideal, but a 35amp ESC is a little light for that. You could step up to an 8x8 prop for a bit more speed on the 3s. Your best bet might be to upgrade the ESC to a 50 amp and do the 4s to get more rpm. A motor upgrade would require a higher Kv rating. One thing you have to remember is the plane as it is stock will have a lot of drag in the wing and the wider fuse.

@Sero has built the FT Racer with a narrow fuse and a speed wing, now he has also gone to 4s and even higher I think. He has clocked his plane at almost 120mph, which I guarantee is more then double what you are seeing now. This is a link to the thread https://forum.flitetest.com/index.php?threads/ft-racer-narrow-fuse-speed-wing.58854/
 

Sero

Well-known member
#5
A higher KV motor means you need to drop to a smaller diameter prop, with the stock Racer you want to stick to 7" or bigger prop as the size of the fuselage is large and will block a lot of the prop wash. Keep in mind that if you move to 4s or a higher pitched prop with your existing electronics you will have to switch to a smaller prop to keep the amp rating the same.
With your existing setup I'm thinking you can increase the amp loads on your existing motor, I would try 4s with the 8x6 prop and monitor you motor temps, your ESC should be fine. With good airflow over you motor and ESC you usually can go over spec, heat is the killer. Ideally you should pick up or borrow a watt meter to be sure your not way over spec.
https://hobbyking.com/en_us/turnigy-180a-watt-meter-and-power-analyzer.html

If you want to upgrade your motor this is a good one. You shouldn't need to change your ESC
https://hobbyking.com/en_us/propdrive-v2-2830-1200kv-brushless-outrunner-motor.html
The FT Radial C-pack would also be a good choice., both of those motors would be the best next step-up IMO.

If you need to buy a 4s battery get the highest c- rating you can get, preferably 40c or even 60c. Voltage sag slows the plane quite a bit and pulling high amounts of amperage out of a low c-rated battery will shorten its life dramatically.

Next concern would be your wing, high speeds with heavy batterys takes its toll on the spar, it should ideally be re-enforced with aluminum, wood or carbon fibre. My first Racer was bone stock airframe and I ran a 4-500 watt motor on it and the wing was getting pretty soft, you could see creases on both wings near the root and eventually you could see the wings had more than stock dihedral while flying.
Make sure you have dual rates set-up and keep the elevator throw as low as possible on low rates. High rates for slow to moderate speeds, low rates for high speeds. Turning hard and fast will be hard on the spar so reducing that will help dramatically but you will need more flying space.
 

mrjdstewart

Well-known member
#6
i run your setup on 4S with a 9x4.5 prop in my racer and it is still not very fast. gonna have to swap the motor and maybe esc depending if real speed is what you want.

good luck,

me :cool:
 

Sero

Well-known member
#7
i run your setup on 4S with a 9x4.5 prop in my racer and it is still not very fast. gonna have to swap the motor and maybe esc depending if real speed is what you want.

good luck,

me :cool:
Finding that perfect prop/motor combo can sometimes take some trial and error. Have you tried a 8x6? Props are obviously the cheapest/easiest to change first.
 

mrjdstewart

Well-known member
#9
Finding that perfect prop/motor combo can sometimes take some trial and error. Have you tried a 8x6? Props are obviously the cheapest/easiest to change first.
if i want to go fast, i have planes for that. 120 mph no prob. i like the looks of my racer but not the way it flies. not sure what i did during the build or if it's just the way it is but it is far from my favorite plane to fly.

laters,

me :cool:
 

Sero

Well-known member
#10
if i want to go fast, i have planes for that. 120 mph no prob. i like the looks of my racer but not the way it flies. not sure what i did during the build or if it's just the way it is but it is far from my favorite plane to fly.

laters,

me :cool:
I found the Racer suffers from weak directional stability. On the Racer this causes some dutch roll and stalls at high speed, high angle of attack. My current Racer I added a ventral fin and dorsal extension which has so far addressed those problems. I also eliminated the dihedral which helps reduce the dutch roll. Both are easy add ons to any existing plane, you can see the forum thread link in my bio for more info.
 

BATTLEAXE

Well-known member
#11
I found the Racer suffers from weak directional stability. On the Racer this causes some dutch roll and stalls at high speed, high angle of attack. My current Racer I added a ventral fin and dorsal extension which has so far addressed those problems. I also eliminated the dihedral which helps reduce the dutch roll. Both are easy add ons to any existing plane, you can see the forum thread link in my bio for more info.
Actually I remember Josh and David talking about that in the release vid saying it didn't need all that vertical surface area and kept the Vstab small. I might build one here soon and I will be using some of your mods in your build to correct these things off the start. Granted mine won't be as fast as yours but it doesn't hurt to have it done just in case there are 4s batts in my near future
 

Sero

Well-known member
#12
Actually I remember Josh and David talking about that in the release vid saying it didn't need all that vertical surface area and kept the Vstab small. I might build one here soon and I will be using some of your mods in your build to correct these things off the start. Granted mine won't be as fast as yours but it doesn't hurt to have it done just in case there are 4s batts in my near future
Actually, the opposite, the first one David built didn't have enough vertical, they had to increase it. Really could be bigger or taller yet.
At high angle of attack it gets shrouded but the fuse, that's where the ventral fin does its job. The dorsal extension will help with the dutch roll.

I enjoy flying the Racer, even when built to plans, I would just add those mods to the tail.

Video starts where David talks about the tail.
 

BATTLEAXE

Well-known member
#13
Actually, the opposite, the first one David built didn't have enough vertical, they had to increase it. Really could be bigger or taller yet.
At high angle of attack it gets shrouded but the fuse, that's where the ventral fin does its job. The dorsal extension will help with the dutch roll.

I enjoy flying the Racer, even when built to plans, I would just add those mods to the tail.

Video starts where David talks about the tail.
I gotta watch the build vid again too, this plane has recently intrigued me