Hi all, I'm asking for some help, but I have searched first...way too much actually. And I'm going to leave links to help as well.

The plane will be about 27-30 oz. all up weight, that's assuming a 70 gram motor.

The plane is a Cessna/Cub style foamie with full house controls and large control surfaces. I forget the wing loading, but it came out really low as it has a large wing, I believe it was 11 or so on the chart, on the low trainer range loading. Sorry, I'm a bit new to this and I can't find that wing loading calc. and don't have the cord measurements in front of me.

Since this thing can handle some weight I thought it might be fun to give this baby some power. Not sure if that will be too much against it's nature though?

My budget is tight. I'm looking at mostly UH motors. If there is another motor though that is only about 30 dollars I would consider paying the extra, so feel free to tell me what you think about the Scorpions, Welgard, Ele motors of the world as well.

https://www.unitedhobbies.com/UNITED...idProduct=5112

70 grams, 63 for the D version

https://www.unitedhobbies.com/UNITED...idProduct=3883

77 grams

https://www.unitedhobbies.com/UNITED...idProduct=4700

56 grams

https://www.unitedhobbies.com/UNITED...idProduct=2105

67 grams

https://www.unitedhobbies.com/UNITED...idProduct=2106

85 grams

These weight's don't seem right, but I'm a newbie so I don't know. The TP I have seen in person and from the pictures some of these other motors look pretty huge, but the weight's listed don't seem much different except the 22-20L. I saw a pic of the 35-30 and thought it looked huge.

I would like to run 2S in parallel, maybe 850 mah or so in order to allow me to have some cells to use in smaller models. I can go a bit bigger if I have to though.

Do you think I could run on 2S at all? Not sure if 2S can put up a 25 ounce bird?

I guess I'll be trying to watch my amp draw as well to accomodate run time and the lower Mah's

Please mention ESC amps needed as well.

Thanks much for your time!

Anthony

You can run 2S, but you will need a motor with higher Kv. Forget the smaller motors, they don't have enough power for your model.

The KD-36-22S (1440Kv) should give good performance with a 10x5 or 10x7 prop on 2S.

https://www.unitedhobbies.com/UNITED...idProduct=2126

The motor is rated for 28A so a 30A ESC would suffice.

Thanks for the input!

Trouble is I'm on the fence about 2S or 3S, it's most likely going to be 3S of about 850 mah and then parallel them.

So you favor the big motor huh, I guess I should look at the 22-20L and that 35-30C then if I go 3S?

If I do go 2S and higher KV, what size pack will give me decent runtime?

With a 10x7 prop the full throttle current should be about 25A, and a 2500-2S Lipo would give reasonable run time (about 14 minutes at 70% throttle).

The A22-20L with 9x6 prop on 850-3S2P should get similar run-time.

Thanks, that's good news, I didn't think I would be able to get those kind of run times.

So should I just flip a coin and pick a motor?

That 35-30 I believe is said to have better build quality, but I'm not sure. A pic I saw made it look huge and it made me worried that UH has the weight wrong.

That 22-20 got a nice write up by Miljenko on UH. It pulls 20 amps on a 10x5 for almost a thousand grams of thrust, I believe that was on 3S 2100 or 2200, but 7 minute run time. This things is made of EPS, I might just tear of a wing with that kind of performance.

The weights are correct. The 35-30 is similar to other motors of the same size. The KD A22-20L may seem heavy for its size, but that is because it has a long stator (iron is much heavier than aluminium).

I have both motors and the build quality of each is suspect, just as you would expect at these prices (my 35-30 had a mis-routed winding and tight bearings, the KD A22-20L's bell was off-center. Luckily I managed to fix these faults).

The KD A22-20L is a bit more efficient than the 35-30-1100Kv (especially at higher power levels) so should give longer run time when appropriately propped, but the 35-30 will also be fine if you don't expect too much from it. The 35-30's thicker shaft and shorter length may make it a bit more crash-resistant.

Aman

I am developing a small program in where treatment to obtain that type of use, that prop and that volts is appropriate for a motor knowing the initial datas the manufacturer.
Only Feed Kv. Volts, Amper, Weight motor and efficiency estimated.

post 806.

https://www.rcgroups.com/forums/show...603636&page=54
https://www.rcgroups.com/forums/showthread.php?t=670859

I hope can help you.

Manuel V.

Originally Posted by Bruce Abbott

The weights are correct. The 35-30 is similar to other motors of the same size. The A20-20L may seem heavy for its size, but that is because it has a long stator (iron is much heavier than aluminium).

I have both motors and the build quality of each is suspect, just as you would expect at these prices (my 35-30 had a mis-routed winding and tight bearings, the A20-20L's bell was off-center. Luckily I managed to fix these faults).

The A20-20L is a bit more efficient than the 35-30-1100Kv (especially at higher power levels) so should give longer run time when appropriately propped, but the 35-30 will also be fine if you don't expect too much from it. The 35-30's thicker shaft and shorter length may make it a bit more crash-resistant.

I'm a bit confused. I'm looking at the 22-20, the 20-22 and the 22-15, the 20-20L is much smaller hacker style, the blue one...the only blue one that looked appropriate was the 20-22...you said the smaller one's probably would be out, so I figured that meant the 20-22 and 20-20, they are even lighter than the Tower Pros.

Did you mean 22-20L?

Originally Posted by manuel v

Aman

I am developing a small program in where treatment to obtain that type of use, that prop and that volts is appropriate for a motor knowing the initial datas the manufacturer.
Only Feed Kv. Volts, Amper, Weight motor and efficiency estimated.

post 806.

https://www.rcgroups.com/forums/show...603636&page=54
https://www.rcgroups.com/forums/showthread.php?t=670859

I hope can help you.

Manuel V.

Thanks, I have come across your very helpful posts in the past. Unfortunately I find the calculators hard to learn how to use and I often can't get all the numbers from the manufacturer to input. I also don't have excel, but I will probably download open office.

And I don't mean your calculators in particular, I mean in general.

I guess I should have put Hacker vs. AXI in my title.

Certainly noone on an internet forum owes anyone a response, but it is unfortunate when there are so many knowledgeable people out there who can help, but often times only chime in when it has to do with defending there particular opinion on some matter.

Also, I feel I did my internet duty by researching first and trying to offer the reader as much info about my plane and needs.

Peace,

Anthony

Originally Posted by aman_74

Did you mean 22-20L?

Yes, sorry about that. I have now corrected that post.

It doesn't help that UH's 'Hacker style' motor was originally designated HXT25D-28 (which is printed on the case of the motor), then they changed it to KD A20-20L but their website still shows the old motor. Now they also have a lower Kv 'A20-22L' but with exactly the same picture of their old motor - no wonder I got confused!

I guess I should have put Hacker vs. AXI in my title.

Huh?

Hacker vs. Axi would have assured that more than one person chimed in with motor advice.

Your help is much appreciated, but it's always good to get more opinions and on more than just UH motors.

I thought my explanation about people not replying explained my little joke about Hacker vs. AXI arguments.

My point is that people put far more wasted energy into brand defending then they do sharing of information.

Aman.

I think that is easy.

You only feed with Manufacturer Data in Yellow Box. and Pink Box off the table.
and you recive data in Green Box and Blue BOX:

In the pictures i put data for your question motor.

Manuel V.

Remember this when people trash Uh and other "cheap" websites,it's better to crash a cheap motor than an expensive one. If youv'e got the money buy good stuff if not UH is a great place to buy from IMHO,
Bob

Originally Posted by manuel v

Aman.

I think that is easy.

You only feed with Manufacturer Data in Yellow Box. and Pink Box off the table.
and you recive data in Green Box and Blue BOX:

In the pictures i put data for your question motor.

Manuel V.

Thanks for this Manuel. Is there any way I can tell approximate amp draw? Or not since we aren't actually testing the motor.