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-   -   Motor and Plane Sizes (http://www.Wattflyer.com/forums/showthread.php?t=74039)

dereckbc 07-08-2014 01:39 AM

Motor and Plane Sizes
 
Can anyone direct me with a link that covers various plane sizes and motors? No need to cover scale as I get that.

Motors have me real confused like size 10, 15, 25 ect which I think mean equivilent to gas mm size.

Then I see on sites like Hobbyking 32-40 act which seem to be physical dimensions.

Trying to figure out how to upgrade a plane motor for a little more power. For example I have a plane with a EF 15-BL, and I think I can use a 25 BL from Heads Up RC, but not certain. What it boils down to I do not know what I am looking for and with hundreds of motor out there is very confusing.

Plane sizes also has me a bit confused. For example a 300 or 400 size. I know that is some measurement but what?

rcers 07-08-2014 01:46 AM

Here is what I do, as it is all very confusing, just as you point out.

Forget the size, name, dimensions. Simply look at the weight of the motor.

So if you have a 100g motor it will produce 300watts of power. If the plane is 3 lbs that is 100w/pound. That is great sport power for a propeller system (EDFs need more power due to inefficiencies).

This saves the hassle and overestimation of power from various motor manufacturers. Trust me many lie!

3w/g is a good power estimation. Very high quality motors (efficient) and large motors (over 500g or so) are generally in the 4-5w/g rating.

Now you really know what power the motor can produce. This will help you get the right size motor for your plane and power requirements...

This formula works wonderfully for me.

Mike

kyleservicetech 07-08-2014 01:50 AM

Quote:

Originally Posted by dereckbc (Post 952461)
Can anyone direct me with a link that covers various plane sizes and motors? No need to cover scale as I get that.

Motors have me real confused like size 10, 15, 25 ect which I think mean equivilent to gas mm size.

Then I see on sites like Hobbyking 32-40 act which seem to be physical dimensions.

Trying to figure out how to upgrade a plane motor for a little more power. For example I have a plane with a EF 15-BL, and I think I can use a 25 BL from Heads Up RC, but not certain. What it boils down to I do not know what I am looking for and with hundreds of motor out there is very confusing.

Plane sizes also has me a bit confused. For example a 300 or 400 size. I know that is some measurement but what?

Question:
What size model, weight model, and power system are you interested in?

Electric power can vary from little tiny models that fly on 20 Watts or so, to the 3000 Watts I'm running on my giant Big Stick model.

There are a number of very good computer programs out there. The one I use is www.motocalc.com, free for 30 days, then $39. This and similar type programs are only as good as the specs on the motors provided by the mfg. Some of those specs are not worth the paper they are written on.

What will work out fairly well is the number of watts per pound of airplane. Around 90-100 watts per pound will perform well on most model types. And, 150 Watts per pound will be an excellent performing model.

dereckbc 07-08-2014 02:51 AM

Quote:

Originally Posted by kyleservicetech (Post 952465)
Question:
What size model, weight model, and power system are you interested in?

Well that was one of my questions is plane sizes. It is a Parkzone Extra 300. So I think 300 is the size, but not really sure what that means. I suspect wing span or area?

Quote:

Originally Posted by kyleservicetech (Post 952465)
There are a number of very good computer programs out there. The one I use is www.motocalc.com,

I have that program is one of my sources of CONFUSION. When I input what is already in the plane the program says it will not work. Well the exact motor, ESC, Battery, and Prop are not in the program.

There are hundreds of motors in that program and I cannot figure out how to filter them out and tell what is what.

hayofstacks 07-08-2014 04:26 AM

Read up on headsuprc.

Reading up on different motors and the thrust/amps they put out taught me more about motors then anything else. not a bad place to order from either.

most motor manufactyres give you almost nothing to go off of making it really hard.

dereckbc 07-08-2014 04:58 AM

Quote:

Originally Posted by hayofstacks (Post 952476)
Read up on headsuprc.

Read up what?

solentlife 07-08-2014 08:17 AM

The weight of motor is a good guide to power output ... and a good foundation.

But I use a second item after that ........... what prop is recc'd for the motor. Most sites even Hobby King will give a rec'd prop and Voltage pack ...

I also have a little calculation I do ... once I have the motor size, weight and prop ... I then decide what LiPo I will use by KV x Volts .. looking for decent rpm figure .... and style of flying ...

Nigel

Flubber 07-08-2014 01:43 PM

It is easy to get spun around by all the numbers, but just think of them as guides.

Your Parkzone plane is a model of a full scale plane called an Extra 300, so those numbers just tell you what it looks like and nothing else. It is an aerobatic sport plane.

It weighs 34.5 oz (980grams) and to fly well it would need a motor that can provide 34.5 oz of thrust from a prop that is around 10.5 X 9 (very high pitch). This would be a 1 to 1 weight to thrust ratio. If you are careful and hold the plane vertically while going to full power, you can see if it would pull straight up out of your hand. This shows if it has a 1:1 thrust ratio. To increase performance you need to increase thrust through a more powerful motor that can fit in the plane and provide that thrust with a similar diameter prop. That is the hard part in my book.

To proceed I would need motor dimensions from the stock motor and prop adapter to make a reasonable choice. If I had wattage numbers from the current motor, it would help. A motor that is rated at higher watts would be considered more powerful. The stock specs for your plane show a 30 amp esc and a 3 cell battery. That would put the wattage at about 330 watts estimated max. Going to 550 watts would be a upgrade.

And lastly are your batteries holding their voltage, because this stock set up seems to pull alot of amps with that high pitch prop? If the voltage drop is making you feel like you need more power new batteries that can handle the current draw would make the plane feel more powerful.

If you want more from your plane you need to know what it has now as far as thrust, watts, amps and volts. Those are the parameters that we use to get the smiles on our faces when we fly our modified models.

rcers 07-08-2014 02:20 PM

Quote:

Originally Posted by dereckbc (Post 952470)
Well that was one of my questions is plane sizes. It is a Parkzone Extra 300. So I think 300 is the size, but not really sure what that means. I suspect wing span or area?

300 on your Extra refers to the model of airplane this is modeled after.

http://en.wikipedia.org/wiki/Extra_EA-300

It just so happens "300" when in reference to an RC electric power system is an old reference to a brushed "can" motor we used to use in the early days of electric.

There was 180, 280, 300, 400, 480, 500, 600 and 700. "Speed" was a common add on name - even though most of our planes then were not very speedy. :)

Speed 300's and 400's were very common sizes for small airplanes.

See here:http://www.electrifly.com/motors/speed400.html

They were mostly geared (to get the most advantage out of them) and the smaller the number the smaller the size of the motor.

It has nothing to do with the airplane size, wing area, span etc.

A speed 300 motor was good for 7-8 amps (70-80w) and flew smallish planes. The Speed 400 was good to 10-11 amps (100watts or so). 600's were good in the mid 20's (~300w).

Quote:

Originally Posted by dereckbc (Post 952470)
I have that program is one of my sources of CONFUSION. When I input what is already in the plane the program says it will not work. Well the exact motor, ESC, Battery, and Prop are not in the program.

There are hundreds of motors in that program and I cannot figure out how to filter them out and tell what is what.

Yep - my advise differs from that above. You can pretty much skip the programs. While they are good for "general" information too much varies in battery capability, altitude, motor and ESC variables to really make them or more than just passing value, again IMHO. Spend 100% of you eCalc money on a Wattmeter. That tells you real stuff, for your real equipment, at your location. It is MANY TIMES better than a electric motor calculator program.

If you are wondering what to buy - before you can test with the wattmeter, I use the forums, see what others use ask questions and get a good start. Knowledge will almost always involved someone trying to do exactly what you are, add more power. If you were to search the forums for "more power on parkzone Extra 300" I bet you find a wealth of info. Try several forums, use Google too!

Once you have been at it for a while - you get the hang of sizing systems pretty well.

Again - I use the motor weight. It works very well for me. It does not boast about power (something some motor manufactures LOVE to do...) and has been spot on for me in 98% of my applications.

Trust me - forget about the motor stats. Just look at the weight.

Lets take your plane for example...

It uses a cheap brushless motor that weights in about 140g or so. That is a motor good for 420-450 watts, using my 3w/g figure above.

You want more power. I would shoot for a motor that weighs about 175w or so. That will take you to 525-550 watts or so. That will be about a 20% power increase...

That is generally very noticeable.

IMHO, small changes are best. You would not want a 300g motor on that plane. Why? Because it is too heavy, needs a larger, heaver esc and battery. All this adds weight and decreases overall performance. You start getting into diminishing returns. It is all a balance.

Now I will admit - other things are important (besides the weight). You want to pay attention to the wind of the motor (the kV i.e. how fast the motor spins) so you can swing the right propeller with your selected battery too. So again the forums rock. Start a thread with "Upgrade my Extra 300 - Need more power!". You will get lots of sharp guys and gals telling you what might be good.

Better yet - you will likely find someone that did exactly what you want - and is happy. That is gold! Forums rock....

Make sense?

rcers 07-08-2014 02:43 PM

I did a quick search - just to illustrate my comments above:
http://www.rcgroups.com/forums/showthread.php?t=1261571
http://www.rcgroups.com/forums/showthread.php?t=1415005
http://www.rcuniverse.com/forum/park...etup-tips.html

Also - just to add "more things" have you tried a different prop? Sometimes that is all the upgrade you need! :)

Mike

Abuelo 07-08-2014 05:08 PM

Quote:

Originally Posted by dereckbc (Post 952481)
Read up what?

Check the HeadsupRC site. Across the top in blue are several sub sites and one is for Help and Technical. Easy to overlook as we usually go there seeking a specific product.

Try: http://www.headsuprc-info.com/brushl...tor-guide.html

dereckbc 07-08-2014 11:25 PM

What I am trying to do in this case is slow my Extra 300 down and lesson the torque roll down from the high pitch prop. Danf thing wants to roll hard left and takes a lot trim and fighting to keep it level flying at light speed. More than this novice can handle. The dang thing is too fast for me and I want to slow it down a bit.

All I really know about the motor in the plane is it is a 15 size 950Kv swinging a 10.5 x 9 prop. Thinking a 11 x 5 may tame it down but not sure that will work with the stock motor and ESC

rcers 07-09-2014 02:17 AM

That will slow it down, but the Extra 300 is NOT a slow down airplane. Doing so will stall/snap! The 11x5 will likely be fine however. The pitch is good on these planes as you really do need to keep the speed up.

You need a VisionAire. :)

Mike

dereckbc 07-09-2014 02:41 AM

Quote:

Originally Posted by rcers (Post 952570)
You need a VisionAire. :)

I have one and yes it is much easier to fly. There is another guy in my club with an Extra 300. Good 3D pilot. All he did was change the prop to I think was a 11 x 5.5. Slowed it down quite a bit and can do limited 3D with it. To take off all he does points it straight up in his hand, full throttle, and up it goes. To land he just Harriers it and sits the tail on the ground and cut throttle. On the 4th he did a full FLAT SPIN Landing with it and set it down gently. He just flies the Extra as a toy. His real passion is 3D Helo's and he is great at it. Kind of scary how fast the 3D choppers are. Had me standing behind steel poles under supporting steel roof. That and Ron Moore (aka Moron) flying his 200 mph jet.

hayofstacks 07-09-2014 03:45 AM

What you want is thrust not speed then. it would be possible to just throw a 10x5 on it and have fun. or just throttle back. you don't have to fly it at 100mph with the throttle all the way up. higher speeds change trim settings. if your rolling or having a hard time keeping it trimmed, more likelt then not, your going to have a warped wing or not properly aligned surfaces. maybe you trimmed it in with a touch of rudder, then used aleroins and elevator to correct it. this would get way worse at speed and change the way the air flows.

CHELLIE 07-09-2014 12:28 PM

Quote:

Originally Posted by dereckbc (Post 952557)
What I am trying to do in this case is slow my Extra 300 down and lesson the torque roll down from the high pitch prop. Danf thing wants to roll hard left and takes a lot trim and fighting to keep it level flying at light speed. More than this novice can handle. The dang thing is too fast for me and I want to slow it down a bit.

All I really know about the motor in the plane is it is a 15 size 950Kv swinging a 10.5 x 9 prop. Thinking a 11 x 5 may tame it down but not sure that will work with the stock motor and ESC

Its just not motor and plane size, the prop size and pitch makes a heck of a lot of difference, if your using a 10.5 x 9 prop right now, a 11 x 5.5 will work just fine, when you reduce the pitch by 2 you can increase the diameter by 1, thats just a rule of thumb, but its always a good idea to check your amperage with a wattmeter, and it makes no difference to the motor if you use a prop that is with in reason of the motor limitations, you could even use a 8x4 prop on your motor, and the motor and esc would not care, but if you go to big on the prop and pitch, the motor and esc will scream bloody murder :D LOL take care and have fun, Chellie


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