Mustang Fever

My Feedback: (2)

Sorry, Ed. Guess I assumed you were familiar with Laddie's designs. Pic attached. 22.5" wingspan, 22-24 oz RTF. The Astro 020 is a brushless, souped up speed 400, basically.
The 100% version of this is 46-60 glow powered, spans 45" or so, and weighs about 5.5 pounds. (It's a follow on to the old Northstar, which you may remember.)

It is possible to keep water out of seaplanes- I do it routinely, but if your opinion is that cooling of battery, ESC and motor is critical, I'm going to put a couple holes in the top deck so I can route air over the battery and the ESC. I can do the same thing for the motor, as there is a gap between it and the left and right sides of my nacelle, so I could mount scoops there and let the cooling air go out the back, as it is open at this point.

I had two of these propulsion units in a Jim Ryan P-38, and one of them just died. I think it may be because I had no provision for cooling. Lasted a long time, though, probably because I used to cruise around at less than half throttle. I think I did this because, looking at the Astro instructions, there is no mention of cooling. Too long ago to really remember, though.

Mustang Fever

My Feedback: (2)

Hey, Ed:

Here's what I ended up doing. By carefully positioning holes in the fuse formers under the inlet and outlet, I can direct airflow over the battery and the ESC .

Thanks for the info.

aeajr

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Mustang Fever,

How has your cooling arrangement worked. Theroy is great but people will benefit from a report on actual results.

Do you check the components for heat? Any problems? Any changes since December?

Anything you would do differently at this time? Your experience will be useful to others.

Mustang Fever

My Feedback: (2)

Hey, Ed

So far, so good. No signs of overheating or power loss. I've only been able to make maybe 5 flights, as the weather in my part of lower Michigan has been so awful. The battery charges up like it did when new, and shows no loss of capacity.

I did some limited testing of the system by blowing through the intake with a straw that had a piece of clay around it to seal it. A healthy airflow came out the exit, so I think the battery and esc are getting good flow around them.

Warmer weather will tell me more, that's not gonna be for awhile. I do hope to fly it during the next week at my club in Colts Neck, NJ. Don't think the temp is going to be much above 35F, tho.

Later.

aeajr

My Feedback: (2)

Thanks for the update. As you said, you will have to say how it does in hot weather, but seems you are good for winter work. Enjoy!

Dr_Arnold

My Feedback: (4)

I have a question about the wire gauge used to connect the batteries to the ESC. The batteries (2) I am using come with 12 gauge power leads and the ESC also has 12 gauge power leads. I want to connect the batteries in series and put an arming switch in between the batteries and the ESC so I purchased the MPI Arming switch and MPI series cable, both of these come with 14 guage wiring. Since both the batteries and the ESC have 12 guage wires, is it going to cause problems if I use 14 guage wire between them? My concern is having the 14 guage wire overheat.

Batteries are Zippy Flightmax 5000mAh 6S1P 20C - two connected in series for 12S1P
ESC is Pentium 100A-HV ESC
Motor is HXT 80-85-A 250Kv Brushless Outrunning
Prop Mezjlik 22x10 3-blade hollow cardon fiber

aeajr

My Feedback: (2)

I don't know where this arming switch sits in the circuit so I can't say for sure. But if the current to the motor will flow through that 14 gague wire, then you have good reason to be concerned.

If everything is built out of 12 gague, they did it for a reason. If you put 14 in the middle, you create a point of higher resistance. Depending on the amperage you are pulling this could be a problem. How many amps are you expecting to be drawn through the system?

If you connect in series you will double the voltage. Will your ESC and your motor handle that voltage?

You should only do this with matched packs.

Dr_Arnold

My Feedback: (4)

I expect to be pulling about 4500 watts.

Both the moter and the ESC are rated for voltage up to 48 volts.

I guess I will have to build my own arming switch.

campcrafter

Hi aeajr,

the detailed write up has been a very useful tool for me to understand the electric way. I however am confused on a few questions. what power set up will i need for the multiplex easycub that i want to use for AP. the equipment will be around 250gms. i wanted to go for a 350 watt set up. do you think i am right. can you please suggest the power plant for the same ( motor, ESC ). i will use a 11.1 2200mah 20c battery for the same. what flight time will i get. thanks.

aeajr

My Feedback: (2)

250 grams would be around 9.5 oz or about .6 pounds. If you use the watts/pound rule and multiply 50 watts, 75watts and 100 watts X .6 you will get a good feel for what is needed.

So, if your all up weight is .6 pounds, 60 watts would be plenty. Of course that depends on what performance you want, which you did not state.


I won't get more specific than that. The goal here is for you to apply what you have learned, not to ask me to do it for you.

campcrafter

thank you for your reply.

I have already stated that the cub will be used for AP, i.e. aerial photography.

i have gone thru your writings and i have to complement you, that my knowledge of electrics has been phenominally enhanced , thanks to you again.
now my confusion is about the amperage, voltage, wattage kv, that are mentioned or not mentioned on the specification by the company. then what is the way out. see the links below.

http://www.multiplexusa.com/power_an...power_pack.php here the is Himax 2816-0890 Brushless Motor, where the dimension is 28 x 33, then why 2816?

http://www.hobbycity.com/hobbycity/s...trunner_1200kv. we know the voltage, where's the current mentioned? what do we do? can we rely on the vendors word? what if there's a typographic error?

http://www.hobbycity.com/hobbycity/s..._1400Kv_/_470w Here the Rated Power: 470w is mentioned and in the configuration table: Power(W) 345 is written. How does a novice like me understand.
If you can explain this, it would benifit many.
thanks again.

jetboard

Very informative thread. It answers all my questions except one. You seem to be the man that could help me. I have a brushless motor/esc manned project where I would like to apply full throttle to the motor without the use of a receiver or any RC. Is there a switching device I can use to tap into the esc? What I'm looking for is a manual switch I could activate, ideally with a 5-6 second run time that would automatically shut off the motor until activated again. It's a crazy project but that's what I need. Any help would be greatly appreciated.

aeajr

My Feedback: (2)

Don't know. Sorry

aeajr

My Feedback: (2)

So, is a 2 minute climb to 400 feet adequate? Or do you want to hit 1000 feet in 20 seconds? What performance level do you want? AP is an application that tells me NOTHING about the performance level you require.

I am not going to do this for you. That link goes to the Multiplex site. The specs say this is a 200 watt set-up. So, what will the combined weight of the plane and the equipment be? I want YOU to do the math. Note that there are 28 grams to an ounce and 16 ounces to a pound.


Watts/weight = watts/pound


Well, if you doubt what the vendor posted, then you can buy the motor and test it with a watt meter. Or you can read all the posts provided by users of that motor. There are a lot of them. Have you read them? The information is right there at the link you posted.


Again, the owners of that motor have posted the configurations they have used.

If you go back and read the article, you will recall that a motor does not automatically produce a certain amount of power, it depends on the voltage of the battery and the size of the propeller.

If the manufacturer does not post enough information for your needs, and you don't trust the information posted by users, I suggest you go to another motor.

Himax posts a LOT of information about their motors. Their site can be found at:
www.maxxprodd.com

If you go back to the first post and loo a these two articles. One of the resources mentioned is motorcalc. Tell it the motor and it will recommend prop, esc an battery combinations. THAT is the easiest way for a novice to proceed.

3 ............Sizing Power Systems
4.............Props vs. Amps

I hope that helps.

campcrafter

okay, so it was a matter of misunderstanding, i get your point now. The added weight for AP is what i supposed meant the performance. How ever you take that as the application, and the speed and climb as the performance. Now i see your point.

thanks, do keep adding your knowledge. It helps people like us understand things better.

thanks again.

rc flylow

I'm building a ducted fan model and need to extend the leads (12-14 inches) from the 45 amp ESC (Electrifly) to the Ammo in-runner motor driving the fan. (24-45-3790kV) constant current = 25A, maximum surge current = 50A. At 11.1V maximim constant watts = 278. The best wire I can find in the hobby store catalogs is 12ga silicone manufactured in this case by Deans. I use Deans connectors so this seems to be the right wire but I don't find any data showing current ratings. Have I got the right wire for this application? Is there a source somewhere to size and purchase the proper lead wire?Ducted fans will typically physically separate the ESC from the motor and will require longer leads. Thanks for your help!

aeajr

My Feedback: (2)

Good luck with your project.

Check with the maker of the ESC before you do this. Iseem to recall that most ESC makers recommend against extending or modifying the ESCto motor leads. The reason is back EMFsensing.

In order for a brushless ESCto work it has to sense where the rotating parts are so it knows when to switch the various windings on and off.On a brushed motor, this is handled mechancally by the commutator. Ona brushless motor this ishandled by the processor inside the ESC.

On early brushless set-ups they used sensors on the motor to read the position. Later they learned that the spinning components created a "back voltage on the wire" that they could read and use to tell when to switch the power on and off.In order to do this the length of the motor to ESCwire must be known, or so I understand. I am not an electrical engineer, but I seem to recall reading this in one of the ESCinstruction sheets.

So check with the ESCmaker before making any mods to those wires.

rc flylow

Thanks a bunch! I'm glad I asked the question and I'll check with Electrify on the leads.

aeajr

My Feedback: (2)

Let us know what they say.

rc flylow

So far, no response from Great Planes Electrifly on the length of the leads from the ESC to the motor. I did find this statement in the ESC manual:

I don'r expectany more info but if I do I'll let you know.

aeajr

My Feedback: (2)

OK then, I stand corrected. You just made a valuable addition to this discussion. Thanks for posting that.

That sounds like what I read. I just recalled it from the wrong side. Ihave never had to extend either.


RTFM


Sounds like you can extend the motor side.

Use wire that matches the gague of the wire being used now.

Mustang Fever

My Feedback: (2)

"Use wire that matches the gague of the wire being used now."

Or one size bigger if the distance is significant.

rc flylow

I received a response for Elecrify. Doesn't help me much because I must move the battery far from the motor or have a 5 lb airplane. Here it is:

Mustang Fever

My Feedback: (2)

You can make the leads from the battery to the speed control as long as you need to. Just leave the wires between the speed control and the motor as is.

rc flylow

Thanks all. I'll do exactly that. The ESC will be in the tail next to the ducted fan motor (in the airstream for cooling purposes) and I'll lengthen the battery leads just enough to get the battery in the nose. Makes sense to increase the wire guage as well to cut down on potential voltage loss.