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Motor trouble

Old 03-05-2021, 01:56 PM
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Beaststyle536
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Exclamation Motor trouble

Well, i am a beginner RC builder, but not at all stranger to building in general. I have a FLYSKY I6X transmitter and Ia6b receiver along with a 16.8 volt max esc controlling a EMAX Mt 1806 460g (just over a pound) thrust motor. Powered by a 3s battery, this all sits inside my foamboard P47 "model". its close but not exact. it sits at around 283g with everything inside. What im here about, however, is the motor. Would this 460g motor be enough to sustain flight? Please ask for any other needed details
Old 03-08-2021, 10:32 AM
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jester_s1
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That motor can handle about 125 watts, so yes, it's more than powerful enough for that plane. It may be too heavy though.
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Old 03-09-2021, 04:05 PM
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So i would need to lighten up the plane?
Old 03-10-2021, 03:46 AM
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As said the motor/thrust will be more than enough for this plane, the most important thing is to make sure the COG is correct. Jester was implying that the plane might be quite nose heavy with this large motor.

You can get it all setup to fly, and then just hand toss it into some some tall grass, or similar to see how it glides. If it shoot upward its probably tail heavy, if it quickly nose dives it probably nose heavy. Of course this assumes all control surfaces are setup properly.

Let us know your results.
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Old 03-10-2021, 08:08 AM
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OK, I'll ask what everyone is dancing around. You do know the model needs to be balanced in the fore / aft direction? And do you know where it needs to balance? i.e. the CG (or CoG).

That said and assuming you know. Nose heavy models are usually balanced by adding weight to the tail if it's not too much. The tail being longer has an advantage where one ounce could offset as much as 5 ounces in the nose. Reducing weight from the nose helps but is often limited by the need to keep a strong motor connection to the rest of the model. You do not want to weaken the structure. With electric you can start by moving the motor battery and ESC back as far as there is room and wires allow. Do not add wire to the motor circuit. Some people find it helpful to stick their tail servos in the tail making the added weight functional. Of course all this is easier to do while building the model vice after it's built.
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Old 03-10-2021, 04:49 PM
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OK. The CG works to be a inch or so behind the wing, which is located around 3 inches from the nose. The entire plane works around 1.5 to 2 feet in length
Old 03-10-2021, 04:51 PM
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And something i forgot to say, i will work on testing it, but as for now i have no real tall grass.
Old 03-10-2021, 07:58 PM
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Originally Posted by Beaststyle536 View Post
OK. The CG works to be a inch or so behind the wing, which is located around 3 inches from the nose. The entire plane works around 1.5 to 2 feet in length

That CG would be fine if the wing cord is between 3"-3.25". Any larger and you could be nose heavy, any smaller and you could be tail heavy.
Old 03-11-2021, 08:17 AM
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CG is one concern, but all up weight is another. Too much motor does mean having to add weight in the tail (or move components back) to balance. But it also means increasing wing loading and hurting flight performance. Then if the model winds up being significantly overpowered using the recommended props, amp draw will be high which means needing to go to bigger and heavier batteries. That can be mitigated by going down to smaller props that recommended, which won't hurt the motor at all. But still you'll be carrying weight that has no function.
Old 03-13-2021, 11:01 AM
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Ok. the wing chord (If thats what you mean by cord) is around 4 inches. ill move it back slightly.
Old 03-14-2021, 04:21 AM
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OK! Don't take this the wrong way but when you say about 3 inches back, or around 1.5 to 2 feet. Such measurements are pretty much useless.

3 inches back? Back from what? The end of the fuselage structure or the prop? The measurement should be taken from the prop (maybe you did and I just missed it). Measuring anything should be done with a ruler or measuring tape to get a reasonable accurate length. When trying to calculate specifics like a CG, a 6 inch variance on a 2 foot model is a big range for error.

As for the wing. Wing span tip to tip. Wing Cord or the width described as being from the leading edge to the trailing edge. One measurement from right next to the fuselage (root) and one just in from the tip (tip cord). Assuming as you said it's a P-47 model then should I also assume the wing tapers (smaller cord) as it goes from the root to the tip? This impacts proper CG location depending on whether it's a leading edge (LE) taper, trailing edge (TE) taper or both and how much taper.

I'm not going to cry foul on this yet but based on what you've said there's the possibility the wing is too far forward. Though I will say it's not by much. More accurate measurements from the prop back will help to determine that.

The internet has provided a venue where people must rely on their words and meanings for communications. Unfortunately with variations in education, experience levels, even geographic locations what one says and means can often be wrongly interpreted by others. Fuselage length? 18 to 24 inches with or without the 2 inches or so to get to the prop. So just how long is it really? See my point?

Again, I don't mean to get on your case. Instead I intend to educate you and help you learn more about this aviation thing. All too often a thread will dance around things like this causing frustrations for all involved and sometimes causing someone to leave the hobby in frustration. I don't want that to happen and am just trying to cut through to the chase. It's not politically correct but then, neither am I. I'm just trying to get us all on the same sheet of music so to speak.

Last edited by Retiredat38; 03-14-2021 at 04:23 AM.
Old 03-14-2021, 06:30 AM
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Agreed, when looking for help is is always better to provide as much accurate information as possible.
Old 03-19-2021, 08:13 AM
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Not denying good points above but likewise, accuracy with spelling in presenting aviation related concepts are important too - as B536 brought to attention in post #10-

Wing chord should not be spelled "c-o-r-d" as some are doing here.

A cord is a string or rope.
Old 04-10-2021, 12:30 PM
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i tested a little more, and it seems like at full power, the plane merely glides. This is with me running alone and gently tossing the plane before catching it again. The plane glides in the air, then sinks down, and seemingly tries to fly but cant. Also, when i go full throttle on the transmitter, the motor cant do it. it stops and turns 90 degrees at a time. Any ideas why?
Old 04-10-2021, 08:06 PM
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1. What you're doing is really dangerous. You may have noticed how sharp those prop tips are. Don't ever run with a plane in your hand with the motor running, and certainly don't run alongside one flying and try to catch it.
2. If you're that underpowered, I'd suspect the ESC is not programmed correctly or you're using too small a prop. Have you calibrated the ESC to your throttle?
3. Do you mean the prop is only turning 90 degrees? I'd suspect a bad motor if you've calibrated the ESC properly.
4. As I suggest to every new hobbyist, it would be wise to get in person help from an experienced RC pilot.See what's happening is so much more informative than working from a new pilot's description, and an attentive instructor will spot things you didn't even know to ask about.
Old 04-11-2021, 01:51 AM
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Originally Posted by H5606 View Post
Not denying good points above but likewise, accuracy with spelling in presenting aviation related concepts are important too - as B536 brought to attention in post #10-

Wing chord should not be spelled "c-o-r-d" as some are doing here.

A cord is a string or rope.
Yep! Ganging up and bullying people for a missed spell check error is WAY more important than helping someone properly set up a model. What would we ignorant folks ever do without all of you?
Old 04-11-2021, 11:05 AM
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Ok, so the motor problem was fixed by a quick esc calibration. The motor recommends 5 to 6 inch props and came with 2x 6x3 props and that is whats on it. How should i test it if it wont liftoff by itself? Should i buy this kit and build it with my parts? It recommends a 2300kv motor and i have a 2280kv.

Never mind, i cannot post urls. It is a FliteTest mini Corsair electric airplane kit. Go to the fliteTest store and go to airplanes then DIY airplanes then Mini. it was the first model shown for me

Last edited by Beaststyle536; 04-11-2021 at 04:17 PM.
Old 04-12-2021, 05:48 AM
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I'm glad you got the ESC fixed. Are you using the recommended battery voltage and capacity?
I can tell you that you're starting with a plane that isn't for beginners. Even if you do get it to fly, it's going to need a fair amount of speed and won't self-correct. It will have a greater tendency to snap and have takeoff troubles too.
Old 04-12-2021, 06:36 AM
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Originally Posted by Beaststyle536 View Post
Ok, so the motor problem was fixed by a quick esc calibration. The motor recommends 5 to 6 inch props and came with 2x 6x3 props and that is whats on it. How should i test it if it wont liftoff by itself? Should i buy this kit and build it with my parts? It recommends a 2300kv motor and i have a 2280kv.

Never mind, i cannot post urls. It is a FliteTest mini Corsair electric airplane kit. Go to the fliteTest store and go to airplanes then DIY airplanes then Mini. it was the first model shown for me
You mean this one? Mini Corsair

Specifications:
Weight: 270 grams (Fully assembled; without battery)
Wingspan: 29 Inches (737 mm)
Center of Gravity: 1.75 Inches (44mm) from the leading edge of wing (Recommended)
Control Surface Throws: 12 Degrees
Expo Suggestions: 30%

Kit Includes:
  • Laser-cut Foam Airframe
  • 16" Pushrods
  • Control horns
  • Plywood Firewall
  • Corsair Decal Pack
Recommended battery is a 3s LiPo Battery 75C (11.1V/850mAh) and motor is a 2205 2300kV.

If that is indeed the one and if this is indeed your first RC Airplane Model. Then this is NOT the one to start with.


Last edited by Retiredat38; 04-12-2021 at 06:40 AM.
Old 04-12-2021, 12:03 PM
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Beaststyle536
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That is, Why would it be bad? The build video, and i quote, says " This could easily be Someone very first build, and they could have a very good experience with it" This is Josh from Flite test

Here is the link. about 40 seconds in you hit the quote

Last edited by Beaststyle536; 04-12-2021 at 05:23 PM.
Old 04-12-2021, 07:04 PM
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"Could be" is not guaranteed to be.
Josh also wants to sell airplanes.
But it is possible provided the model is built straight, all functions and controls are set up properly and someone experienced actually does a flight test after checking it out.
And you fly it only in dead calm weather.

You have a design based on a WWII fighter. Fighters are not known for their stability. And while models can be re-designed to be more stable, the small size of yours negates that.
You plan to use a motor that is claimed to develop twice the thrust the entire model is intended to weigh. Think about that for a moment.

Most "Trainers", real and models are single engine high (or shoulder) wing with tricycle gear. There are reasons for that. Simple, basic airplanes that are easier to fly than say a twin or a Corsair.
Fact, bigger airplanes also fly better. This is true of real ones as well as models. They are simply more stable. Models appear to react more slowly due to being well seen further away. Able to be flown three mistakes high while being kept in sight.

I do not see a good ending to this effort but, I will answer every question I can to give you the best chance of success. For starters I'd suggest you get the recommended motor, ESC, etc from Flight Test. And find someone local to check it out and test fly it if you can.

And BTW, your CG should be 1.75 inches behind the leading edge.
Old 04-12-2021, 07:13 PM
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Another thought to your performance issues, make sure you have the propeller on correctly. There is a front and back to all props and having one on backwards will reduce the thrust produced.
Old 04-13-2021, 02:39 AM
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Ok. I can work out getting someone to look at it and give some tips and experienced view to show me how to fly it. i will go for the same recommended products, Though the prop size and the battery are the same.

Last edited by Beaststyle536; 04-13-2021 at 03:44 PM.
Old 04-14-2021, 02:44 AM
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And didn't you mention you were using a wood prop? Functionally all props are pretty much the same. But wood props tend to be heavier than plastic and thereby add more load to the motor reducing performance. There are wood props made for electric which don't load the motor as much. However, the plastic props aren't always the best either. The cheap plastic will flex under high rpm and flatten out at the tips more resulting in a loss of thrust. It's all a trade off between price and performance.
Old 04-14-2021, 11:14 AM
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No i am using a plastic one.

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