Microjet 3 motor or ESC or????

[trying2fly]

I replaced orig. motor in Hawk Sky with Grayson MJ3 motor and used my existing ESC.  I was told existing esc would work fine.  With new Charged(12.6 V) 1800 11.1 3s battery, it flew about 30 sec and lost power.  Upon landing motor was very warm on this cold day.  On bench  while running for one min at half throttle...then no response to full throttle?   Going to zero throttle then to full throttle it is anemic  and very gradually losing power and fairly hot.  I have a 6x4E prop.????please help!!!  I hope my new motor is not bad?  What is going on?  My old stock motor was slower but better than this!!!

[OV10]

RE: Microjet 3 motor or ESC or????

Hello trying2fly,

This should also answer your 'Smoking Hot Battery' thread that you posted. Your problem is an incorrect Kv rated motor with the stock ESC.
According to the Dyman spec for your Hawk Sky, it is using a 25A ESC paired with a 400Kv motor.
You installed a 2300Kv motor that is capable of 30A.
Am really surprised that neither the ESC or the battery have not released that magic smoke.
With a 3S battery the 400Kv motor was turning the 6x4E at 4440 RPM whereas the 2300Kv motor is trying to twist it at 25530 RPM. Just laying the numbers out there so you can see how drastically wrong your setup is configured. (RPM's are at max throttle)
Sorry...... but best regards to ya,

[WintrSol]

RE: Microjet 3 motor or ESC or????

OV10 is right - turning a prop at a given rpm is what takes the power, and that power goes up with the CUBE of rpm. Your new motor, assuming you used the same prop, is trying to pull over 190 times as much power as the original motor. I'm surprised it didn't burst into flames. From your other post, it's the battery's internal resistance that saved the ESC. Before trying any more changes to the power system, get a Watt meter; without one, you are looking for a burn-out.

[trying2fly]

RE: Microjet 3 motor or ESC or????

OV10 is right - turning a prop at a given rpm is what takes the power, and that power goes up with the CUBE of rpm. Your new motor, assuming you used the same prop, is trying to pull over 190 times as much power as the original motor. I'm surprised it didn't burst into flames. From your other post, it's the battery's internal resistance that saved the ESC. Before trying any more changes to the power system, get a Watt meter; without one, you are looking for a burn-out.

If I obtained and watt meter and it was significantly high.....what is the answer?  Do I drop back to a 5x5?  Grayson..who sells the motor seems to think the 6x4 would be fine with a 30C esc..(I think that is what I understood and I could definitely be wrong!)  Also...why does the 1800mah battery get so much hotter than the 2200mah?  Internal resistance thing again?  Thank you for your help?  By the way, that was the reason I bought the zippier motor...to go faster and now I am having to drop back to the same prop? Help!
[hr]

Hello trying2fly,

This should also answer your 'Smoking Hot Battery' thread that you posted. Your problem is an incorrect Kv rated motor with the stock ESC.
According to the Dyman spec for your Hawk Sky, it is using a 25A ESC paired with a 400Kv motor.
You installed a 2300Kv motor that is capable of 30A.
Am really surprised that neither the ESC or the battery have not released that magic smoke.
With a 3S battery the 400Kv motor was turning the 6x4E at 4440 RPM whereas the 2300Kv motor is trying to twist it at 25530 RPM. Just laying the numbers out there so you can see how drastically wrong your setup is configured. (RPM's are at max throttle)
Sorry...... but best regards to ya,

The specs on my Hawk Sky  show the motor to be an 1800 Kvp and I think the esc was a 20C.  I have both the 1800mah and the 2200mah rated at 30C and my new esc is a 30C?  I changed the stock prop from a 5x5 to a 6x4 and wow...it got so hot the velco take melted off of it and the motor was too hot to touch?  On the 1800mah battery(new) it got much hotter than the 2200mah.  Motor was very very hot on both of the batteries.  Grayson said some people get by running the MJ3 with the "stock" Hawk Sky esc but I went on and upgraded to 30C.  I put on a 6x5.5 to try that and I believe it actually got worse??

[OV10]

RE: Microjet 3 motor or ESC or????

Hello trying2fly,
I got the Kv rating of the stock Dynam motor off of the Motion site because that was an important factor missing from your original post. If the stock rating is truly 1800Kv, per WintrSol's comment of "power goes up with the CUBE of rpm" you still have a major mismatch. Taking a 1800Kv motor spec'd system to a 2300Kv is putting the top RPM values from 19980 to 25530. That difference of 5550 RPM is a considerable increase. I'm might be inclined to believe that WintrSol might give a short explanation of why if you want to know the math science behind the power factors. Just an FYI, most prop driven RC aircraft have RPM's with an average range of 8000-12000 RPM. There is a lot of interaction between prop size, prop pitch, RPM, watts(measure of power), amps & voltage that influences both the motor and ESC. If you are going to be messing around with electrical power enhancements to your craft, for your safety you may want to do get an understanding of the technology driving it and as recommended by WintrSol, get a watt meter. Am sorry to hear that Grayson misguided you but am gonna guess that the individual doesn't have a technical background on the subject. Just so you can have some reassurance that I'm not just spouting off, in my younger years I was an RF engineer - microwave discipline. So best of luck to you on fixing this issue and on future RC adventures.
Best Regards,

[trying2fly]

RE: Microjet 3 motor or ESC or????

Hello trying2fly,
I got the Kv rating of the stock Dynam motor off of the Motion site because that was an important factor missing from your original post. If the stock rating is truly 1800Kv, per WintrSol's comment of "power goes up with the CUBE of rpm" you still have a major mismatch. Taking a 1800Kv motor spec'd system to a 2300Kv is putting the top RPM values from 19980 to 25530. That difference of 5550 RPM is a considerable increase. I'm might be inclined to believe that WintrSol might give a short explanation of why if you want to know the math science behind the power factors. Just an FYI, most prop driven RC aircraft have RPM's with an average range of 8000-12000 RPM. There is a lot of interaction between prop size, prop pitch, RPM, watts(measure of power), amps & voltage that influences both the motor and ESC. If you are going to be messing around with electrical power enhancements to your craft, for your safety you may want to do get an understanding of the technology driving it and as recommended by WintrSol, get a watt meter. Am sorry to hear that Grayson misguided you but am gonna guess that the individual doesn't have a technical background on the subject. Just so you can have some reassurance that I'm not just spouting off, in my younger years I was an RF engineer - microwave discipline. So best of luck to you on fixing this issue and on future RC adventures.
Best Regards,

It certainly was not my intent to be messing around with electrical enhancements to my plane. I was merely being guided by the experience of others in their suggestion of what motor,batt.,etc would give a more exciting flight.  Since so many on RC Power forum advocated the MJ3 with a new ESC I decided to give it a try.  I am more interested in flying for fun rather than delving into the math.  Thank you  for your input.

[WintrSol]

RE: Microjet 3 motor or ESC or????

Hello trying2fly,
I got the Kv rating of the stock Dynam motor off of the Motion site because that was an important factor missing from your original post. If the stock rating is truly 1800Kv, per WintrSol's comment of "power goes up with the CUBE of rpm" you still have a major mismatch. Taking a 1800Kv motor spec'd system to a 2300Kv is putting the top RPM values from 19980 to 25530. That difference of 5550 RPM is a considerable increase. I'm might be inclined to believe that WintrSol might give a short explanation of why if you want to know the math science behind the power factors. Just an FYI, most prop driven RC aircraft have RPM's with an average range of 8000-12000 RPM. There is a lot of interaction between prop size, prop pitch, RPM, watts(measure of power), amps & voltage that influences both the motor and ESC. If you are going to be messing around with electrical power enhancements to your craft, for your safety you may want to do get an understanding of the technology driving it and as recommended by WintrSol, get a watt meter. Am sorry to hear that Grayson misguided you but am gonna guess that the individual doesn't have a technical background on the subject. Just so you can have some reassurance that I'm not just spouting off, in my younger years I was an RF engineer - microwave discipline. So best of luck to you on fixing this issue and on future RC adventures.
Best Regards,

It certainly was not my intent to be messing around with electrical enhancements to my plane. I was merely being guided by the experience of others in their suggestion of what motor,batt.,etc would give a more exciting flight.  Since so many on RC Power forum advocated the MJ3 with a new ESC I decided to give it a try.  I am more interested in flying for fun rather than delving into the math.  Thank you  for your input.

Well, the kV of the stock motor is 1800, so the power increase is just double (23/18 cubed); since the battery voltage remains the same, you are doubling the current. Since the Hawk Sky comes with an 18A ESC, we can assume it draws less than that, perhaps 15A, so doubling that gives 30A, more or less, with the original prop. I've seen a few posts that say the motor is good for 30A, but you have to size the prop to keep it that low. One post on that site said he was using a small prop - 5.5 x 4.5, if I recall. If you are using a 6 x 4, that could explain the excessive power. I didn't see anyone on that site give power or current measurements, so, as usual, YMMV. I've seen plenty of power upgrade threads, some more optimistic than others; this is why you should always use a Watt meter to verify every change you make.

[trying2fly]

RE: Microjet 3 motor or ESC or????

Hello trying2fly,
I got the Kv rating of the stock Dynam motor off of the Motion site because that was an important factor missing from your original post. If the stock rating is truly 1800Kv, per WintrSol's comment of "power goes up with the CUBE of rpm" you still have a major mismatch. Taking a 1800Kv motor spec'd system to a 2300Kv is putting the top RPM values from 19980 to 25530. That difference of 5550 RPM is a considerable increase. I'm might be inclined to believe that WintrSol might give a short explanation of why if you want to know the math science behind the power factors. Just an FYI, most prop driven RC aircraft have RPM's with an average range of 8000-12000 RPM. There is a lot of interaction between prop size, prop pitch, RPM, watts(measure of power), amps & voltage that influences both the motor and ESC. If you are going to be messing around with electrical power enhancements to your craft, for your safety you may want to do get an understanding of the technology driving it and as recommended by WintrSol, get a watt meter. Am sorry to hear that Grayson misguided you but am gonna guess that the individual doesn't have a technical background on the subject. Just so you can have some reassurance that I'm not just spouting off, in my younger years I was an RF engineer - microwave discipline. So best of luck to you on fixing this issue and on future RC adventures.
Best Regards,

It certainly was not my intent to be messing around with electrical enhancements to my plane. I was merely being guided by the experience of others in their suggestion of what motor,batt.,etc would give a more exciting flight.  Since so many on RC Power forum advocated the MJ3 with a new ESC I decided to give it a try.  I am more interested in flying for fun rather than delving into the math.  Thank you  for your input.

Well, the kV of the stock motor is 1800, so the power increase is just double (23/18 cubed); since the battery voltage remains the same, you are doubling the current. Since the Hawk Sky comes with an 18A ESC, we can assume it draws less than that, perhaps 15A, so doubling that gives 30A, more or less, with the original prop. I've seen a few posts that say the motor is good for 30A, but you have to size the prop to keep it that low. One post on that site said he was using a small prop - 5.5 x 4.5, if I recall. If you are using a 6 x 4, that could explain the excessive power. I didn't see anyone on that site give power or current measurements, so, as usual, YMMV. I've seen plenty of power upgrade threads, some more optimistic than others; this is why you should always use a Watt meter to verify every change you make.

Albeit there are several assumptions made here for the sake of discussion, ie.  Loss of power curve with specific batteries, a consideration of 15 amps vs rated 18amp, and the true differences in the rpms of the involved motors , you have possibly inadvertently enabled me to understand the solution.  I can surmise, thanx to you, that the problem with overheating can be solved with simply changing the propeller size.  In this way I can alter the load thus changing the draw on the battery and the heat generated .  At the same time I can change the speed and climbing power.  I can just go from a 6x4 to a 6x3 or go from a 6x4 to a 5.5x5.5   Although going from a 6x4 to a 5.5x5.5 would only result in a mathematical difference of only approx. 3%. In any event it is the prop that is the solution to this overheating problem in my particular instance.  Thank you for you input as it has been enlightening !!
Charles

[WintrSol]

RE: Microjet 3 motor or ESC or????

Hello trying2fly,
I got the Kv rating of the stock Dynam motor off of the Motion site because that was an important factor missing from your original post. If the stock rating is truly 1800Kv, per WintrSol's comment of "power goes up with the CUBE of rpm" you still have a major mismatch. Taking a 1800Kv motor spec'd system to a 2300Kv is putting the top RPM values from 19980 to 25530. That difference of 5550 RPM is a considerable increase. I'm might be inclined to believe that WintrSol might give a short explanation of why if you want to know the math science behind the power factors. Just an FYI, most prop driven RC aircraft have RPM's with an average range of 8000-12000 RPM. There is a lot of interaction between prop size, prop pitch, RPM, watts(measure of power), amps & voltage that influences both the motor and ESC. If you are going to be messing around with electrical power enhancements to your craft, for your safety you may want to do get an understanding of the technology driving it and as recommended by WintrSol, get a watt meter. Am sorry to hear that Grayson misguided you but am gonna guess that the individual doesn't have a technical background on the subject. Just so you can have some reassurance that I'm not just spouting off, in my younger years I was an RF engineer - microwave discipline. So best of luck to you on fixing this issue and on future RC adventures.
Best Regards,

It certainly was not my intent to be messing around with electrical enhancements to my plane. I was merely being guided by the experience of others in their suggestion of what motor,batt.,etc would give a more exciting flight.  Since so many on RC Power forum advocated the MJ3 with a new ESC I decided to give it a try.  I am more interested in flying for fun rather than delving into the math.  Thank you  for your input.

Well, the kV of the stock motor is 1800, so the power increase is just double (23/18 cubed); since the battery voltage remains the same, you are doubling the current. Since the Hawk Sky comes with an 18A ESC, we can assume it draws less than that, perhaps 15A, so doubling that gives 30A, more or less, with the original prop. I've seen a few posts that say the motor is good for 30A, but you have to size the prop to keep it that low. One post on that site said he was using a small prop - 5.5 x 4.5, if I recall. If you are using a 6 x 4, that could explain the excessive power. I didn't see anyone on that site give power or current measurements, so, as usual, YMMV. I've seen plenty of power upgrade threads, some more optimistic than others; this is why you should always use a Watt meter to verify every change you make.

Albeit there are several assumptions made here for the sake of discussion, ie.  Loss of power curve with specific batteries, a consideration of 15 amps vs rated 18amp, and the true differences in the rpms of the involved motors , you have possibly inadvertently enabled me to understand the solution.  I can surmise, thanx to you, that the problem with overheating can be solved with simply changing the propeller size.  In this way I can alter the load thus changing the draw on the battery and the heat generated .  At the same time I can change the speed and climbing power.  I can just go from a 6x4 to a 6x3 or go from a 6x4 to a 5.5x5.5   Although going from a 6x4 to a 5.5x5.5 would only result in a mathematical difference of only approx. 3%. In any event it is the prop that is the solution to this overheating problem in my particular instance.  Thank you for you input as it has been enlightening !!
Charles

I found the Grayson site that lists the upgrade kit, and the chart for the motor. It shows the motor drawing ~20A with the 6x4 prop, for an input power of about 220W. I ran their specs through a calculator, and it gave similar numbers. What it all comes down to is that motor is putting just over 120W into the prop, and dissipating about 100W as heat, assuming you fly at full power, so it's no wonder it gets hot. The 'rule of thumb' for motors is about 3W per gram, and that setup is drawing more than 5W per gram, meaning, again, the motor gets hot, assuming a full-throttle flight. Why the battery gets hot is an unanswered question, as 20A is just over 10C, from a battery that is rated 30C; I can't tell from the photos, but suspect the battery is tightly fit into a foam box, with little or no air flow. Still, your description indicates excessive heat, even in that state. It could be the battery rating is part of the numbers game that many battery makers play, and it really can only support 10-15C, unless it has plenty of cooling air.

BTW, the calculator indicates that going to a 5.5x4.5 prop will drop the input power to ~180W, while the power into the prop is still above 110W, which means the motor will run cooler and draw fewer Amps, while the plane's performance will drop very little. With the larger prop, efficiency goes down quite a bit, with little increase in performance. BTW, prop power changes a lot more with diameter than with pitch, so going from 6x4 to 6x3 will make very little difference, while dropping 1/2" makes a much bigger difference.

[trying2fly]

RE: Microjet 3 motor or ESC or????

Hello trying2fly,
I got the Kv rating of the stock Dynam motor off of the Motion site because that was an important factor missing from your original post. If the stock rating is truly 1800Kv, per WintrSol's comment of "power goes up with the CUBE of rpm" you still have a major mismatch. Taking a 1800Kv motor spec'd system to a 2300Kv is putting the top RPM values from 19980 to 25530. That difference of 5550 RPM is a considerable increase. I'm might be inclined to believe that WintrSol might give a short explanation of why if you want to know the math science behind the power factors. Just an FYI, most prop driven RC aircraft have RPM's with an average range of 8000-12000 RPM. There is a lot of interaction between prop size, prop pitch, RPM, watts(measure of power), amps & voltage that influences both the motor and ESC. If you are going to be messing around with electrical power enhancements to your craft, for your safety you may want to do get an understanding of the technology driving it and as recommended by WintrSol, get a watt meter. Am sorry to hear that Grayson misguided you but am gonna guess that the individual doesn't have a technical background on the subject. Just so you can have some reassurance that I'm not just spouting off, in my younger years I was an RF engineer - microwave discipline. So best of luck to you on fixing this issue and on future RC adventures.
Best Regards,

It certainly was not my intent to be messing around with electrical enhancements to my plane. I was merely being guided by the experience of others in their suggestion of what motor,batt.,etc would give a more exciting flight.  Since so many on RC Power forum advocated the MJ3 with a new ESC I decided to give it a try.  I am more interested in flying for fun rather than delving into the math.  Thank you  for your input.

Well, the kV of the stock motor is 1800, so the power increase is just double (23/18 cubed); since the battery voltage remains the same, you are doubling the current. Since the Hawk Sky comes with an 18A ESC, we can assume it draws less than that, perhaps 15A, so doubling that gives 30A, more or less, with the original prop. I've seen a few posts that say the motor is good for 30A, but you have to size the prop to keep it that low. One post on that site said he was using a small prop - 5.5 x 4.5, if I recall. If you are using a 6 x 4, that could explain the excessive power. I didn't see anyone on that site give power or current measurements, so, as usual, YMMV. I've seen plenty of power upgrade threads, some more optimistic than others; this is why you should always use a Watt meter to verify every change you make.

Albeit there are several assumptions made here for the sake of discussion, ie.  Loss of power curve with specific batteries, a consideration of 15 amps vs rated 18amp, and the true differences in the rpms of the involved motors , you have possibly inadvertently enabled me to understand the solution.  I can surmise, thanx to you, that the problem with overheating can be solved with simply changing the propeller size.  In this way I can alter the load thus changing the draw on the battery and the heat generated .  At the same time I can change the speed and climbing power.  I can just go from a 6x4 to a 6x3 or go from a 6x4 to a 5.5x5.5   Although going from a 6x4 to a 5.5x5.5 would only result in a mathematical difference of only approx. 3%. In any event it is the prop that is the solution to this overheating problem in my particular instance.  Thank you for you input as it has been enlightening !!
Charles

I found the Grayson site that lists the upgrade kit, and the chart for the motor. It shows the motor drawing ~20A with the 6x4 prop, for an input power of about 220W. I ran their specs through a calculator, and it gave similar numbers. What it all comes down to is that motor is putting just over 120W into the prop, and dissipating about 100W as heat, assuming you fly at full power, so it's no wonder it gets hot. The 'rule of thumb' for motors is about 3W per gram, and that setup is drawing more than 5W per gram, meaning, again, the motor gets hot, assuming a full-throttle flight. Why the battery gets hot is an unanswered question, as 20A is just over 10C, from a battery that is rated 30C; I can't tell from the photos, but suspect the battery is tightly fit into a foam box, with little or no air flow. Still, your description indicates excessive heat, even in that state. It could be the battery rating is part of the numbers game that many battery makers play, and it really can only support 10-15C, unless it has plenty of cooling air.

BTW, the calculator indicates that going to a 5.5x4.5 prop will drop the input power to ~180W, while the power into the prop is still above 110W, which means the motor will run cooler and draw fewer Amps, while the plane's performance will drop very little. With the larger prop, efficiency goes down quite a bit, with little increase in performance. BTW, prop power changes a lot more with diameter than with pitch, so going from 6x4 to 6x3 will make very little difference, while dropping 1/2" makes a much bigger difference.

Thank you for your research on this matter.  Very informative and explains alot!!The battery is an "Admiral" brand on the one(1800mah) that gets super hot.  The 2200mah Turnigy battery still gets hot but NOT LIKE the 1800mah.  I will buy a 5.5x4.5 prop and try it out per your advice.  I did try a 5x5 and was super disappointed with the APC brand performance.!!  Have you a prop co. preference?  Once again, thanx for your work on this...is was wonderful to be made aware of these things!!
Charles

[WintrSol]

RE: Microjet 3 motor or ESC or????

It certainly was not my intent to be messing around with electrical enhancements to my plane. I was merely being guided by the experience of others in their suggestion of what motor,batt.,etc would give a more exciting flight.  Since so many on RC Power forum advocated the MJ3 with a new ESC I decided to give it a try.  I am more interested in flying for fun rather than delving into the math.  Thank you  for your input.

Well, the kV of the stock motor is 1800, so the power increase is just double (23/18 cubed); since the battery voltage remains the same, you are doubling the current. Since the Hawk Sky comes with an 18A ESC, we can assume it draws less than that, perhaps 15A, so doubling that gives 30A, more or less, with the original prop. I've seen a few posts that say the motor is good for 30A, but you have to size the prop to keep it that low. One post on that site said he was using a small prop - 5.5 x 4.5, if I recall. If you are using a 6 x 4, that could explain the excessive power. I didn't see anyone on that site give power or current measurements, so, as usual, YMMV. I've seen plenty of power upgrade threads, some more optimistic than others; this is why you should always use a Watt meter to verify every change you make.

Albeit there are several assumptions made here for the sake of discussion, ie.  Loss of power curve with specific batteries, a consideration of 15 amps vs rated 18amp, and the true differences in the rpms of the involved motors , you have possibly inadvertently enabled me to understand the solution.  I can surmise, thanx to you, that the problem with overheating can be solved with simply changing the propeller size.  In this way I can alter the load thus changing the draw on the battery and the heat generated .  At the same time I can change the speed and climbing power.  I can just go from a 6x4 to a 6x3 or go from a 6x4 to a 5.5x5.5   Although going from a 6x4 to a 5.5x5.5 would only result in a mathematical difference of only approx. 3%. In any event it is the prop that is the solution to this overheating problem in my particular instance.  Thank you for you input as it has been enlightening !!
Charles

I found the Grayson site that lists the upgrade kit, and the chart for the motor. It shows the motor drawing ~20A with the 6x4 prop, for an input power of about 220W. I ran their specs through a calculator, and it gave similar numbers. What it all comes down to is that motor is putting just over 120W into the prop, and dissipating about 100W as heat, assuming you fly at full power, so it's no wonder it gets hot. The 'rule of thumb' for motors is about 3W per gram, and that setup is drawing more than 5W per gram, meaning, again, the motor gets hot, assuming a full-throttle flight. Why the battery gets hot is an unanswered question, as 20A is just over 10C, from a battery that is rated 30C; I can't tell from the photos, but suspect the battery is tightly fit into a foam box, with little or no air flow. Still, your description indicates excessive heat, even in that state. It could be the battery rating is part of the numbers game that many battery makers play, and it really can only support 10-15C, unless it has plenty of cooling air.

BTW, the calculator indicates that going to a 5.5x4.5 prop will drop the input power to ~180W, while the power into the prop is still above 110W, which means the motor will run cooler and draw fewer Amps, while the plane's performance will drop very little. With the larger prop, efficiency goes down quite a bit, with little increase in performance. BTW, prop power changes a lot more with diameter than with pitch, so going from 6x4 to 6x3 will make very little difference, while dropping 1/2" makes a much bigger difference.

Thank you for your research on this matter.  Very informative and explains alot!!The battery is an "Admiral" brand on the one(1800mah) that gets super hot.  The 2200mah Turnigy battery still gets hot but NOT LIKE the 1800mah.  I will buy a 5.5x4.5 prop and try it out per your advice.  I did try a 5x5 and was super disappointed with the APC brand performance.!!  Have you a prop co. preference?  Once again, thanx for your work on this...is was wonderful to be made aware of these things!!
Charles

APC E props are usually good performers, if they have the size you want; my favorite brand is EMP, but they can be really hard to find (of course). Remember, prop power changes as the square of the diameter, so going from 6" to 5" loses 30% of the power, while the 5.5" is down only about 15% (calculated). That's assuming the rpm stay the same, which they don't with electric power, but you still possibly lost over 20% to a 5" prop, while the 5.5 should only lose about 5%. There are many other factors that make it near impossible to compare props, though, as the exact same spec will give different performance from brand to brand, and even from E type to glow type within the same brand. Generally, E type props are better on electrics, as long as they don't flex too much.

[Colorc]

RE: Microjet 3 motor or ESC or????

I replaced orig. motor in Hawk Sky with Grayson MJ3 motor and used my existing ESC.  I was told existing esc would work fine.  With new Charged(12.6 V) 1800 11.1 3s battery, it flew about 30 sec and lost power.  Upon landing motor was very warm on this cold day.  On bench  while running for one min at half throttle...then no response to full throttle?   Going to zero throttle then to full throttle it is anemic  and very gradually losing power and fairly hot.  I have a 6x4E prop.????please help!!!  I hope my new motor is not bad?  What is going on?  My old stock motor was slower but better than this!!!

This is quite an old thread, but hope my two cents help. I have been flying with this motor four years and you are using it the way it is intended. The 6x4 apc is perfect and gives impressive thrust for its size. What you describe could be a bad bearing or something caught in between the stator and bell that holds the magnets. As you try to run the motor, the extra drag causes it to heat up quickly. These are really easy to take apart and grayson has replacement bearings.
There are rare occasions that the esc is jacked up and creating such a screwy signal that it shuts everything down after a min. Also make sure that your soldering is solid.
Just for the future, use bearing oil every now and them to keep them from freezing up and keep things moving as freely as possible. Guys will gripe how a good quality motor should not need bearing oil, but in reality they all do unless its a sealed bearing, and i havent seen any of these kind of bearings in the small outrunners, cheap or expensive.