First Electric build questions.....

[Doclove524]

I have a couple of foam RTFs.. a Cessna, and an MX2 sport plane. I also have a couple of sport planes one is a 63" 4stroke .91, and the other is an Extra 260 70" with a 20cc gasser. This will be my first electric build. I have bought a Senior Telemaster 94" WS. I have all the Tx/Rx stuff as well as the servos to complete the plane. I have questions as to the Motor, ESC, and Bats that I have purchased to go with it. I bought the Gens Ace Mars Brushles BL4850-340KV moter with the BL75A ESC. I also purchased two 5s 3000mah 20c lipos to go with it. I am wondering if this is a suitable combo for this plane, and if there is anything else I will need to complete the package??

Any info is appriciated guys. Like I said this is my first electric "build" and I think I researched before i bought, buy I want some added info as to my set up.

Thanks!!

[Doclove524]

Any info there fellas??? Somebody say something??!!?

[spad]

All up weight of the airframe?

Amp rating of motor?

Wattage rating of motor?

Are you following any "watts per pound" formula?

[Doclove524]

Weight will be in the 9 / 10 lb range. Actually I used what I think is a comprable size or maybe just slightly larger size motor than the hobby lobby website suggests for this plane?? I don't really know all the wattage ratings for these Electric motors. I know that the sugested motor for this plane was a 515KV. And the motor I bought is a 340KV. Sugested motor uses a 55a ESC and the one I got uses a 70A ESC. The motor I bought is 1650W, and I think 75A. They both seem to turn around the same size prop range.

Thanks for your help Spad!!

[dumo01]

That motor should give you plenty of power for a 9-10 lb airplane, the spec page I found for it :
http://www.hobbypartz.com/98p-mars-b...75a-combo.html

suggests that motor for model weight up to 15 kg, which would give you marginal performance, but still gives you plenty for 4.5-5 kg.

I would suggest spending time looking through this sticky on selecting electric power systems:

http://www.wattflyer.com/forums/showthread.php?t=18521

[rcers]

You will be fine with that Motor and ESC on the Telemaster. 5s packs is an issue though. The 340kV motor would like 6s voltages as a minimum.

I use a 300 kV motor with 6s but have to spin a 19x8 prop to get 1100 watts or so out of that. The thrust is stunning and speed is fine (for the Telemaster).

With 5s you will have to spin a GIANT prop to get the power up. Not sure you will have that with the standard gear.

Not many 3 blade propellers that might get the watts up a bit.

With 5s voltage you likely wanted to get a 500-600 kv motor. 400 kV = 6s and 300 kV = 8s as a general rule.

Here is a good thread for you to read:
http://www.wattflyer.com/forums/showthread.php?t=60742

Mike

[Doclove524]

Thanks Dumo01! Lots of good info there. So you are saying that the spec on the motor I bought says it will fly a plane weighing 33LB or 15KG!!!!???

[Doclove524]

Originally Posted by rcers

You will be fine with that Motor and ESC on the Telemaster. 5s packs is an issue though. The 340kV motor would like 6s voltages as a minimum.

I use a 300 kV motor with 6s but have to spin a 19x8 prop to get 1100 watts or so out of that. The thrust is stunning and speed is fine (for the Telemaster).

With 5s you will have to spin a GIANT prop to get the power up. Not sure you will have that with the standard gear.

Not many 3 blade propellers that might get the watts up a bit.

With 5s voltage you likely wanted to get a 500-600 kv motor. 400 kV = 6s and 300 kV = 8s as a general rule.

Here is a good thread for you to read:
http://www.wattflyer.com/forums/showthread.php?t=60742

Mike

So are you saying that the 5S bats will not power the motor?? Or will it just not get the most out of what the motor is capable of?? Sounds as though the motor is plenty powerful enough for the plane?

[Doclove524]

Originally Posted by rcers

You will be fine with that Motor and ESC on the Telemaster. 5s packs is an issue though. The 340kV motor would like 6s voltages as a minimum.

I use a 300 kV motor with 6s but have to spin a 19x8 prop to get 1100 watts or so out of that. The thrust is stunning and speed is fine (for the Telemaster).

With 5s you will have to spin a GIANT prop to get the power up. Not sure you will have that with the standard gear.

Not many 3 blade propellers that might get the watts up a bit.

With 5s voltage you likely wanted to get a 500-600 kv motor. 400 kV = 6s and 300 kV = 8s as a general rule.

Here is a good thread for you to read:
http://www.wattflyer.com/forums/showthread.php?t=60742

Mike

Crap... Sound like I blew $50 on two bats that aren't right for my setup??
I can run a 15" or 16" prop on this set up... Will that perform ok and not burn up my setup??

[dumo01]

The motor you have will fly a bigger plane than what you have, but only if you pair it up with the right battery and prop. As Mike pointed out, the 5s battery will spin the prop more slowly than a 6s or higher, so you need to use a bigger prop to get the motor to deliver the power it is capable of. This may be a problem depending on how big a prop the Telemaster can use.

Rule of thumb is 50 w/lb will get you off the ground if you are careful, 75 w/lb for a trainer, 100 w/lb for sport, 150 w/lb and up for 3d.

Looks like Mike and I both suggested the same thread as a good place for information

I did a quick and dirty look on Drive calc using a Hacker A50 12L motor (fairly close to your motor), a APC 16 x 10 prop and a 5 s battery puts you around 600 w or so.
A 6s battery would put you close to 950 w, and 8S would put you around 1550 w with a 15 x 10 prop, but it looks like your ESC is maxed out at 6s so that does not help you

[Doclove524]

Originally Posted by rcers

You will be fine with that Motor and ESC on the Telemaster. 5s packs is an issue though. The 340kV motor would like 6s voltages as a minimum.

I use a 300 kV motor with 6s but have to spin a 19x8 prop to get 1100 watts or so out of that. The thrust is stunning and speed is fine (for the Telemaster).

With 5s you will have to spin a GIANT prop to get the power up. Not sure you will have that with the standard gear.

Not many 3 blade propellers that might get the watts up a bit.

With 5s voltage you likely wanted to get a 500-600 kv motor. 400 kV = 6s and 300 kV = 8s as a general rule.

Here is a good thread for you to read:
http://www.wattflyer.com/forums/showthread.php?t=60742

Mike

Mike,
In looking at the specs on the motor it states "Input 2-6S (5V - 25.2V)"
So my 5s bats are putting out 18.5V, is that right? I know nothing about this stuff!! Wouldn't the 5S be enough to power the moor at a decent level??

Thanks for all your help!

[Doclove524]

Originally Posted by dumo01

The motor you have will fly a bigger plane than what you have, but only if you pair it up with the right battery and prop. As Mike pointed out, the 5s battery will spin the prop more slowly than a 6s or higher, so you need to use a bigger prop to get the motor to deliver the power it is capable of. This may be a problem depending on how big a prop the Telemaster can use.

Rule of thumb is 50 w/lb will get you off the ground if you are careful, 75 w/lb for a trainer, 100 w/lb for sport, 150 w/lb and up for 3d.

Looks like Mike and I both suggested the same thread as a good place for information

So is there some chart that would tell me if I use the 5S on a 340KV motor and turn a 16" prop, what kind of wattage I will be producing?? Looks like I will only need 675 - 750 for trainer type flying and 900 - 1000 for sport flying....

Forgive my igroence here guys!! Thaks for your help!

[rcers]

Originally Posted by Doclove524

So is there some chart that would tell me if I use the 5S on a 340KV motor and turn a 16" prop, what kind of wattage I will be producing?? Looks like I will only need 675 - 750 for trainer type flying and 900 - 1000 for sport flying....

Forgive my igroence here guys!! Thaks for your help!

To answer above yes the motor will "work" on a 5 cell battery but you will have to spin a large prop to get the power needed.

I would guess with a 16x10 prop you will be around 450 watts. This is about half the power you need.

A 22x10 will be about 1100w - good power for the Telemaster but a HUGE propeller that is likely too big for proper ground clearance.



MIke

[Doclove524]

So I guess my bottom line question is... Will the plane fly on the 5s battery with a 16" prop without damaging the motor or ESC???

Sorry for being a pain here folks!!

[Doclove524]

Originally Posted by rcers

To answer above yes the motor will "work" on a 5 cell battery but you will have to spin a large prop to get the power needed.

I would guess with a 16x10 prop you will be around 450 watts. This is about half the power you need.

A 22x10 will be about 1100w - good power for the Telemaster but a HUGE propeller that is likely too big for proper ground clearance.



MIke

What are your thoughts on using 6S lipo with a 15"-16" prop wattage wise??

[Doclove524]

Ok all!!! I just ordered all this stuff yesterday and I was able to contact the seller and change the motor ESC selection to 98P-Mars-BL4841-550KV-BL60A-Combo. This as you can see is a 550KV motor and a 60A ESC combo. I believe this is right in line with the suggested motor from the hobby Lobby website for this plane. And I hope this will be perfect with the 5S lipos I ordered?? Thoughts from the Gurus???

Thanks for your help!!

[rcers]

Originally Posted by Doclove524

What are your thoughts on using 6S lipo with a 15"-16" prop wattage wise??

A 6s setup will likely get you about 600 - 700 watts barely enough to fly the telemaster. Not what you want.

[rcers]

Originally Posted by Doclove524

Ok all!!! I just ordered all this stuff yesterday and I was able to contact the seller and change the motor ESC selection to 98P-Mars-BL4841-550KV-BL60A-Combo. This as you can see is a 550KV motor and a 60A ESC combo. I believe this is right in line with the suggested motor from the hobby Lobby website for this plane. And I hope this will be perfect with the 5S lipos I ordered?? Thoughts from the Gurus???

Thanks for your help!!

Much better for 5s.

[Doclove524]

Originally Posted by rcers

Much better for 5s.

Thanks rcers!! And do you think the 550KV motor is plenty for the 9-10lb Telemaster??

[rcers]

What is the weight of the motor? I ask because sometimes the motor manufactures over estimate their power delivery ability.

I use a formula of a max power output of 3 watts per gram of motor weight. It works pretty well to show what a motor can likely do.

Mike

[Doclove524]

Originally Posted by rcers

What is the weight of the motor? I ask because sometimes the motor manufactures over estimate their power delivery ability.

I use a formula of a max power output of 3 watts per gram of motor weight. It works pretty well to show what a motor can likely do.

Mike

Ok so the motor weight is shown at 295g, and is listed as 1250 Watts.
So your saying it's probably more like 885 watts?? That doesn't seem enough for this plane? Would this motor not be a replacement for about a .60 size nitro motor? It is looking to me like this electric flight is way to involved and confusing to be any fun at this point!!!

[Doclove524]

The recomended motor for this is a 515KV motor. I have seen videos of this plane flying with this motor and it seems like plenty of power. Some take offs I've seen are almost straight up! The plane itself will float around under almost no power and seems to fly nicely with the 515KV motor. So do you guys think the 550KV motor will be plenty to fly the plane with ease??

[rcers]

Yep that would be my upper safe limit - just under 900w. For a Telemaster that is good power.

Just remember the days when you were new to Nitro - it was confusing to you then. This will all make sense as you learn the new portions of electric flight. Don't be discouraged as questions!

On you motor choice - I am not a big fan of cheapo Chinese motors for larger models. I have had them fail.

So to me I would look at a bit more quality in the motor you select. Sometimes you really do pay for what you get. Reading that other thread I pointed you too has excellent suggestions for a Hacker power system.

I really like the looks of the new OS motors but have not used them. Other higher quality motors are:

• AXI
• Motrolfly
• Hyperion
• Scorpion

You can trust the ratings on those motors too. Anything with 1100 watts should be just fine.

Mike

[Doclove524]

Originally Posted by rcers

Yep that would be my upper safe limit - just under 900w. For a Telemaster that is good power.

Just remember the days when you were new to Nitro - it was confusing to you then. This will all make sense as you learn the new portions of electric flight. Don't be discouraged as questions!

On you motor choice - I am not a big fan of cheapo Chinese motors for larger models. I have had them fail.

So to me I would look at a bit more quality in the motor you select. Sometimes you really do pay for what you get. Reading that other thread I pointed you too has excellent suggestions for a Hacker power system.

I really like the looks of the new OS motors but have not used them. Other higher quality motors are:

• AXI
• Motrolfly
• Hyperion
• Scorpion

You can trust the ratings on those motors too. Anything with 1100 watts should be just fine.

Mike

Thanks Mike! Sorry for the slight venting there.... The AXI motor is the suggested motor on the Hobby Lobby Website. But for the size I need we are looking at $159 just for the motor!! Still need a good ESC and Batts!! I have several planes and have been spending way too much on the hobby lately!!! My RFT planes I'm sure have the cheapo motors you speak of and I have had very little problem with them to speak of. I will most likely put together a really nice power package that could be used in my 70" sport plane as well as I get into the electric world a little more..
I really appreciate all your advise and help, I would be lost without the pros!!

[Doclove524]

Originally Posted by rcers

Yep that would be my upper safe limit - just under 900w. For a Telemaster that is good power.

Just remember the days when you were new to Nitro - it was confusing to you then. This will all make sense as you learn the new portions of electric flight. Don't be discouraged as questions!

On you motor choice - I am not a big fan of cheapo Chinese motors for larger models. I have had them fail.

So to me I would look at a bit more quality in the motor you select. Sometimes you really do pay for what you get. Reading that other thread I pointed you too has excellent suggestions for a Hacker power system.

I really like the looks of the new OS motors but have not used them. Other higher quality motors are:

• AXI
• Motrolfly
• Hyperion
• Scorpion

You can trust the ratings on those motors too. Anything with 1100 watts should be just fine.

Mike

One last bit of info if you do not mind... What would be the suggested prop size for my set up??

Thanks again,
Mark