Hi! I'm planning on building my first RC airplane, which means essentially buying a lot of different Equipment like servos motors etc. I saw a video by Joyplanes where he built a plane with a 1.3 meter Wing and 0.9 meter fuselage. My point is that the plane was big. For the plane he recommended a 1000KV motor that weights 33g. Then i looked at another video and saw about the exact same plane but smaller size, 1 meter Wing and 0.7 meter fuselage. The plane was a bit smaller than the previous but very similar. In that plane he recommended a 33g motor with 2200 KV. Now, to the question. Can the 1000 KV motor be used on the smaller plane? It was able to lift the bigger plane so the smaller one should be no problem right? Or is the extra KV that the other motor had necessary for the smaller plane to fly? To sum it up I'm wondering what the extra 1200KV the smaller plane had does? Is it simple just because it will make the plane go faster or is that extra KV crucial for the smaller plane?
Need help! I'm building my first RC plane!
- Thread starter Creylo
- Start date
NickRehm
Member
The short answer is that both planes will probably fly with either motor just fine. The long answer requires a bit of knowledge on the type of airplane, desired flying qualities, and specific capabilities of the motor. In general, higher kv = smaller prop = faster airplane. lower kv = larger prop = slower airplane. This is a rule of thumb and not always true!
If I have a 1.3m wingspan plane and want it to fly sporty/slow, I would go with a larger kv motor with a (relatively) larger prop like an 8x4 or 9x5. That same motor/prop will fly just fine on a similar flying style 0.9m wingspan airplane, no questions asked. Now, you could also fly both of these planes with a higher kv motor (e.g. 2300kv) and a smaller prop like 6x4. They will fly faster and will not be able to accelerate as quickly as the lower kv / larger prop. This may not be desirable for the larger airplane, but might fit the smaller airplane well depending on how you want it to fly.
This is just an extreme case of different kv leading to different applications; 200kv difference in your two motors is not that drastic of a difference, so it would ultimately come down to more information about the motors such as max thrust or current with a particular prop. It could be the case that both motors have similar current capability, in which case: pick the one that gives more thrust for the same current. It could also be the case that the 1200kv motor can only draw up to say 10 amps, but the 1000kv motor can draw up to 30 amps. The 1000kv motor can give much more power (thrust!).
At the end of the day, look at the motor specs and make sure it can give adequate thrust (greater than 1:1 T:W ratio guarantees you can fly comfortably). If there is no thrust data for that motor, look for a similar one with similar kv and similar current rating; the thrust data will be very similar.
If I have a 1.3m wingspan plane and want it to fly sporty/slow, I would go with a larger kv motor with a (relatively) larger prop like an 8x4 or 9x5. That same motor/prop will fly just fine on a similar flying style 0.9m wingspan airplane, no questions asked. Now, you could also fly both of these planes with a higher kv motor (e.g. 2300kv) and a smaller prop like 6x4. They will fly faster and will not be able to accelerate as quickly as the lower kv / larger prop. This may not be desirable for the larger airplane, but might fit the smaller airplane well depending on how you want it to fly.
This is just an extreme case of different kv leading to different applications; 200kv difference in your two motors is not that drastic of a difference, so it would ultimately come down to more information about the motors such as max thrust or current with a particular prop. It could be the case that both motors have similar current capability, in which case: pick the one that gives more thrust for the same current. It could also be the case that the 1200kv motor can only draw up to say 10 amps, but the 1000kv motor can draw up to 30 amps. The 1000kv motor can give much more power (thrust!).
At the end of the day, look at the motor specs and make sure it can give adequate thrust (greater than 1:1 T:W ratio guarantees you can fly comfortably). If there is no thrust data for that motor, look for a similar one with similar kv and similar current rating; the thrust data will be very similar.
Wow, that is unbelievably helpful! A huge issue for me has been that I've been afraid that the 1000kv motor won't for for smaller planes, but now I know that they will work alright! The motor can draw at maximum 10 amps. The propeller recommended in the description with the motor is a 1060 propeller, however i feel like that might be too big of a propeller if i wanted to make smaller planes. By smaller planes i mean around 8000mm-1000mm wing length.
You have been so incredibly helpful! Lately I've been having doubts if i should even build an RC plane since all the equipment i need to buy is around 200$ and things just started to get too complicated. Now I'm back on track and ill do my best to make this dream a reality. I don't mind at all if my plane is slow, that is perfect for a newbie like me. Also, does wingspan mean the length of the wing?
After all the loads of recent information i have decided im going to make a plan with the wingspan 900mm, the motor is 25*35mm 1000kv, 10 amps max i think with 1060 prop, 30 Amp ESC, 3S 2200 mah. I'm not sure what the motor weighs. If there anything i should change to improve the plane feel free to reply. My goal with the motor is to be able to reuse it for different planes in the wingspan range of 8000mm - 1300mm
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