Knief Racer - New Product & Build

[MikeRC]

ooohh, I believe I engineered the setup for that guy!
Should reach about 180 MPH on 3s and break 220 on 4s. You're going to want to go to a 100A ESC on 4s though instead of the 70A that's in there though.

for sure , I will be going 4s, is that prop 5.5 x 6.5 right for the 4s 2200 mah set up? Also is there any favorable ESC you recommend , since size is a big factor on this plane.. thank you again for help..

Mike RC

 

[Jarron]

for sure , I will be going 4s, is that prop 5.5 x 6.5 right for the 4s 2200 mah set up? Also is there any favorable ESC you recommend , since size is a big factor on this plane.. thank you again for help..

Mike RC

On that prop, you'll be pulling just over 91 Amps. eCalc is kinda yelling at me about motor temps and current limit for that motor, but with throttle management you'll be ok. I like these APD ESCs the best for speed stuff. No BEC, so you'll have to use a separate one. : https://neumotors.com/apd-electronic-speed-controls-for-brushless-motors/apd-120f3-brushless-esc-2/

Sometimes I modify props. If you were to reduce your prop diameter to 5" by taking off 12.7mm from each blade, you can get away with the 80A: https://neumotors.com/apd-electronic-speed-controls-for-brushless-motors/apd-80f3-brushless-esc/
You'd get even more speed too.

 

[JustinMader]

Would an IDS servo linkage kit work on this plane, or are the control surfaces too small? I'm keen to try them, but they seem tricky at best to install.

 

[Wayne]

Think this plane is probably too small to fit the trays into the pockets.

 

[JustinMader]

Are 8mm servos the only size that will fit in here, similar to the Mini Q?

 

[Wayne]

You can also use 6mm.

Yep - Pretty much need to stick with the 8mm stuff. One could use a bumped out servo cover and use a thicker servo, but yuk..

We really like the new FrSky servos for these planes.

 

[JustinMader]

Am I correct in guessing you have to keep the aileron servo leads long because the wing needs to be removed to insert the lipo?

 

[Jarron]

Am I correct in guessing you have to keep the aileron servo leads long because the wing needs to be removed to insert the lipo?

If you want to keep it plugged into the receiver all the time, yes, but you could also install a 6 pin connector to simplify removing and installing the wing.

 

[JustinMader]

If you want to keep it plugged into the receiver all the time, yes, but you could also install a 6 pin connector to simplify removing and installing the wing.

So something like this maybe?

 

[Wayne]

Yes, that will work, but make sure it is a good connector. There are a lot of cheap versions of that connector out there these days that are not the most reliable. I like the MPX 6 pins, never had an issue with them:

6 Pin Wing Connector

Multiplex style wing connector with 6 pins.

alofthobbies.com

 

[JustinMader]

@Wayne is it obvious in the fiberglass fuse where the carbon is? I'm hoping to keep all my antennas internal but would need to plan around the carbon areas.

 

[Wayne]

Most are painted black, so not really.

 

[JustinMader]

Most are painted black, so not really.

Thanks, guess I'll have to find out the hard way

 

[JustinMader]

Thanks, guess I'll have to find out the hard way

What timing, the plane just showed up. And you can see in the fuse and tail boom where the carbon starts and stops.

 

[JustinMader]

@Wayne cheers for the build pics! You mentioned grinding down the rear fuse to allow control horn clearance at down elevator. Am I correct in guessing you removed some material on the inside of the boom roughly in the circled green section?

 

[Wayne]

I honestly do not recall. Chances are things may have changed since I made mine, TJI is always looking to improve the products.

 

[JustinMader]

I honestly do not recall. Chances are things may have changed since I made mine, TJI is always looking to improve the products.

Got it, thanks, shouldn't be too hard to figure out. I'm really liking the TJI planes, very nice quality.

 

[JustinMader]

X-ray is getting the same treatment as the Mini Q. Since it can hold 21700s, the goal is 120+mph for 10+ minutes.

 

[Jarron]

X-ray is getting the same treatment as the Mini Q. Since it can hold 21700s, the goal is 120+mph for 10+ minutes.

ooooooh

 

[Wayne]

That goal should be very easy to achieve. I'd guess you could do that with a little over 300 watts.

Jarron had a small setup that consumed about 230 watts with 100 mph speeds. (single motor)

The dual motor will cost you a lot of extra watts, but since you are not trying to go super fast, should be very doable.