Motor decision
- Thread starter Blackbird
- Start date
KV is "RPM per volt", so higher KV will give higher prop speed at WOT. For high power, the reason "Low KV/Long Prop" or "Extremely high KV/tiny prop" are popular choices is effects on blades at high speeds.
To push more air (more thrust) we need to either get a longer prop with steeper pitch, or spin it faster. However, the longer the blade, the faster the linear speed out at the tip. When the linear speed on the tip goes too high the blade stops working as designed. So we get a really long prop it'll really pull hard, but we've got to spin it slower to keep it working, hence low KV/long prop.
There is a point where we could go the other way, shortening the prop, kicking up the RPM, and still keep the tip speed down. The balance can get more thrust out of the shorter prop, but it's a bit more tricky and has harder limits to what you can get.
In performance, higher KV gives a more responsive thrust production -- nice for zippy flying that takes advantage of throttle management. Lower KV takes longer to change from one RPM to the next -- something carrying FPV gear or a candy drop gets the power it needs, but the throttle will feel a little sluggish in comparison.
To push more air (more thrust) we need to either get a longer prop with steeper pitch, or spin it faster. However, the longer the blade, the faster the linear speed out at the tip. When the linear speed on the tip goes too high the blade stops working as designed. So we get a really long prop it'll really pull hard, but we've got to spin it slower to keep it working, hence low KV/long prop.
There is a point where we could go the other way, shortening the prop, kicking up the RPM, and still keep the tip speed down. The balance can get more thrust out of the shorter prop, but it's a bit more tricky and has harder limits to what you can get.
In performance, higher KV gives a more responsive thrust production -- nice for zippy flying that takes advantage of throttle management. Lower KV takes longer to change from one RPM to the next -- something carrying FPV gear or a candy drop gets the power it needs, but the throttle will feel a little sluggish in comparison.
Probably the better direction to go anyways. If your design mounts the engines on the wings, make sure you have enough room to spin the longer props w/o hitting the fusealge.
Really depends what is mounting to what, but most of my mounts/firewalls are custom cut from 1/8" birch plywood. Nothing magical about the material, just what they make thin hobby plywood with, and 1/8" is just about right for thickness for the motors I use.
That is then screwed/glued/taped to a matching hardpoint in the frame (typicaly a built-up flat spot made from the same foam). Typically, if the hardpoint is near a spar, the hardpoint foam is extended and glued/taped to the spar as well, so there's a good mechanical connection to the frame.
The supplied motor fixture (like an x-frame or barrel mount) is then screwed & glued to the firewall.
If this doesn't work for your design, some more details would help us point you to a workable solution.
That is then screwed/glued/taped to a matching hardpoint in the frame (typicaly a built-up flat spot made from the same foam). Typically, if the hardpoint is near a spar, the hardpoint foam is extended and glued/taped to the spar as well, so there's a good mechanical connection to the frame.
The supplied motor fixture (like an x-frame or barrel mount) is then screwed & glued to the firewall.
If this doesn't work for your design, some more details would help us point you to a workable solution.
Craftydan ,I just got a Turnigy D2822/14 @1450kv with a 30amp esc going to use a 7.5 prop will mount on a FT Versa pusher config will this be okay to mount a GoPro in the front , I was going to use a Turnigy D2826/6 2200KV with 40amp and a 6.4prop
so if i use 1450kv and 7.5 prop will this give me more torque (push) on take-off? also using a 3s lipo 2200mAh 20c
so if i use 1450kv and 7.5 prop will this give me more torque (push) on take-off? also using a 3s lipo 2200mAh 20c
