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Mini Arrow - I want to build the beast.

Mode 1

Active member
#1
Hey All.

I've decided I want my first build of the year to be an insanely fast Mini Arrow. I've got a couple of arrows now with the quickest running an Emax RS2205s 2600kv on 3s. It's pretty quick, but i'm looking for more speed (above and beyond dropping a 4s in my current plane.) As I don't know much of anything about motors and electronics I need some help. What type of engine should I be looking for to achieve extreme top end speed without having to modify the plane to accommodate the engine size or prop? I see some engines running 4100kv but they are very small.. like 1407 or 1507.. I'm not even sure if engines like this would work in something like an arrow or if high kv translates to speed. I'm simply Looking for some education.

Any and all suggestions/feedback would be appreciated. Happy New Year!

~ Dave


Here's one such 4100kv engine that caught my eye. https://www.getfpv.com/brotherhobby-tornado-t1-1407-4100kv.html
 
Last edited:

kdobson83

Well-known member
#2
Those higher kv motors are much smaller, they fit on micros and micro quads like the gremlin. They don't produce the power you'll need. Just run 4s on the motor you have with a 5x4x3 prop and you'll be around 100mph. I have a similar setup on my alpha and while I haven't flown it yet the thrust it produces while holding it and my experience thus far I'm expecting 80-100mph top speed.
 

Mode 1

Active member
#3
Those higher kv motors are much smaller, they fit on micros and micro quads like the gremlin. They don't produce the power you'll need. Just run 4s on the motor you have with a 5x4x3 prop and you'll be around 100mph. I have a similar setup on my alpha and while I haven't flown it yet the thrust it produces while holding it and my experience thus far I'm expecting 80-100mph top speed.
Thanks for the response. It's much appreciated.
 

Arcfyre

Well-known member
#4
In my opinion, a "22” sized motor is about the biggest can size you can fit on a mini airframe (like the arrow). Anything larger (28, 35, 42, etc) and you need the larger firewall of the non-mini models to mount the motors. Additionally, it would be unlikely that you get an arrow to balance if you throw a much bigger motor in the tail pod.

I too wanted a fast wing, and I loved my arrow for it's design and handling. What I ended up doing was building a versa wing, and then upscaling the electronics pod from the arrow to fit the versa. Gave me much more room in the aircraft for powerful electronics and larger batteries.

My fast wing runs a 3536-1800 kV on 3S with an 8x6 prop and a 70A ESC. I run 2 1500 mAh batteries in parallel, giving me about 5 minutes of flight time.

But oh God those 5 minutes are epic... Lol

Here is the motor I use. It's a monster.

https://hobbyking.com/en_us/propdrive-v2-3536a-1800kv-brushless-outrunner-motor.html
 

Captain Video

Well-known member
#5
Hey Folks:
Last year (2018), my sons and I put a 4S 1300 into a mini arrow and it flew so fast it stripped off the brown paper off the FT foam board! Ok, a little exaggeration but it had a 40a esc and a red bottom 2205. Very quick!!:cool:
 

Morgan

Active member
#6
You could try a 2306 2450 kv. I know that it will work on a mighty mini and it has insane amounts of thrust on 3s much less 4s.
 

kdobson83

Well-known member
#8
I personally would do what's stated above and build a bigger ship first. Like the Versa, or what's on my list, the Spear and put a BIG watt sucking higher kv motor on it. But be careful what ever route you take. The faster you go the more stress you out on the airframe. You may want to think about reinforcement like carbon arrow shaft spars and reinforced fusealage (depending on the frame you chose).
 

Mode 1

Active member
#9
Hey all. thanks for the fantastic feedback. Where would I be able to purchase carbon shafts to reinforce my wings?

Thanks!
 

Arcfyre

Well-known member
#11
Hey all. thanks for the fantastic feedback. Where would I be able to purchase carbon shafts to reinforce my wings?

Thanks!
Walmart sells arrows for hunters that work well. Alternatively your local hobby shop will likely carry them in the same section as their building materials. If you still can't find any, simple wooden dowel rods from Home Depot or Lowe's are an acceptable, although slightly heavier, alternative.
 

kdobson83

Well-known member
#12
Hey all. thanks for the fantastic feedback. Where would I be able to purchase carbon shafts to reinforce my wings?

Thanks!
Yes, go to Walmart in the hunting section. You can get em for about $2-3. Pretty much any sporting goods store like Dicks, Academy, and Bass Pro also carry them, but they may cost a bit more. I LOVE reinforcing wings with arrow shafts. They are cheap, SUPER strong, and easily cutable. I use a tiny hacksaw with small teeth, cuts right through it. I've also used a bread loaf knife from my kitchen knife set, works great in a pinch but if the knife is cheap may dull the blade quickly.
 

Arcfyre

Well-known member
#13
I forgot to mention that I built my fast wing out of the Elmer's foam board. It's significantly sturdier than the DTFB, but quite a but heavier. I also used paint stirrers as spars on the inside to make the structure as rigid as possible.

Here's a few shots of it. The wingspan is unchanged from a normal versa, but it has a center pod similar to the arrow to house electronics. Hands down my favorite bird.

20181104_153829.jpg Resized_20181104_153252_3513.jpeg
 

Arcfyre

Well-known member
#15
That is a nice looking wing!
Thank you. I'm thinking of building another one with a few minor changes just because I like it so much. I need to get a video of it flying because the sound it makes while flying is half the thrill.

@Mode 1 I apologize for hijacking your thread a little. You just touched on a subject that I am passionate about: fast wings. Also, if you don't mind me asking, whereabouts in Michigan are you? I'm in SE Michigan about 50 miles outside Detroit.
 

kdobson83

Well-known member
#16
I forgot to mention that I built my fast wing out of the Elmer's foam board. It's significantly sturdier than the DTFB, but quite a but heavier. I also used paint stirrers as spars on the inside to make the structure as rigid as possible.

Here's a few shots of it. The wingspan is unchanged from a normal versa, but it has a center pod similar to the arrow to house electronics. Hands down my favorite bird.
I see in your pictures you have some stencilled on letters. Do you have a printer? Try printing the letters, then cover the letter front and back with packing tape, then cut and glue. I have done this trick with multiple planes now and it works awesome. Here's an example of what it looks like.
IMG_20181211_113730_01.jpg 20180902_172921.jpg 20171129_110835_HDR.jpg
Basically making ANY lettering/image you want into decals for your planes/projects. Well, what ever fits on a 8.5x11 sheet of paper. Bigger images should be printable at Staples or similar print shops tho. I cut them out using a combo of scissor and an xacto knife. And I use 3m super77 spray glue to attach it to the plane. Sorry to go off subject there just saw your lettering and thought I'd give you a simple hack to add life to your builds.
Oh, and if you want white lettering, just do hollow letters and cut inside the black lines leaving you with the white inside the printed letter.
 

Arcfyre

Well-known member
#17
Haha yeah, my stenciling is terrible. Your planes look great! Thanks for the tip on printing out letters. I'm going to need to try that.
 
#18
A suggestion on wing stiffening. My favorite is using the thin plastic packing straps that come on larger shipments, or bundles. They are only about 1/16" thick and roughly 1/2" wide, usually green, black, or white in color. The trick is use one on both sides of the foam so they line up. In order for it to flex in one direction the other side would have to stretch, and it cant. A bead of ca glue is all it takes and sticks like crazy to foam that has a coat of poly on it. Cheapest option around if you work where larger shipments come in from time to time, plenty of it headed to the trash.
 

Mode 1

Active member
#19
I actually have a box of carbon fiber arrow shafts in the basement. Apparently, I was over-thinking the solution. Thanks!