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-   -   How to determine what motor to use? (http://www.Wattflyer.com/forums/showthread.php?t=72712)

Technopro 12-03-2013 01:36 AM

How to determine what motor to use?
 
Ok, so new to the Rc plane world and was wondering how to determine what motor and prop to use. I lately just found a model that's built to fly but has no electronics or servos in it. It's made of wood and fabric and has a wooden propeller. It's a T-6, Harvard model with less perfect accuracy. It's wing span is just under 53" and is 35" long. It weighs less than a pound(pretty close though). All control surfaces move but some are jammed with tape that is unneeded and can easily be fixed. The main wing is detachable.

What I need to find out is what electric motor and other electronics I should use for a low cost.(brand new to flying and will probably crash it within 5 flights)????

FlyWheel 12-03-2013 01:43 AM

There are a number of downloadable programs, some free, that can figure this out for you, Moto-Calc is one, but there are others. Google can be your friend.
https://www.google.com/#q=moto+calc

hayofstacks 12-03-2013 01:52 AM

take the weight of the plane ready to fly. this should be easy to find with a quick Google search.

I like a 1:1 or higher thrust to weight ratio another thing to consider is if you need to add lead if you need lead in the nose, might want to run a larger motor/battery combo and then underprop it. at less then a pound empty, id guess a 400-450 class motor. if it were me, id probably just throw a 450 sport on it from www.headsuprc.com with a 30 amp esc, 10x5 prop and 1800-2200 mah 3 cell. pulls about 38 oz of thrust. this may also depend on your prop clearance though. if you only have enough room for a 7 or 8 inch prop, you might want a different motor or battery.

Technopro 12-03-2013 02:45 AM

Ok so hayofstacks, your saying a 400-450 class motor, a 30amp esc, a 10x5 prop(?) and a 3 cell 1800-2200mah battery.

First, Could you recommend a good 450 class motor(brushless) and propeller combo.(current display prop is 9' long)

Second, a good esc and battery?

Last, what's a good transmitter and receiver combo?

Thanks,
Techno

kyleservicetech 12-03-2013 03:21 AM

Quote:

Originally Posted by Technopro (Post 933004)
Ok so hayofstacks, your saying a 400-450 class motor, a 30amp esc, a 10x5 prop(?) and a 3 cell 1800-2200mah battery.

First, Could you recommend a good 450 class motor(brushless) and propeller combo.(current display prop is 9' long)

Second, a good esc and battery?

Last, what's a good transmitter and receiver combo?

Thanks,
Techno

There are a lot of good radios out there. If you'd like to see what people are using, take a look:
http://www.wattflyer.com/forums/showthread.php?t=71276

The Spektrum DX7 series along with a full range receiver is a good start. Spektrum also has a $100 transmitter/receiver combo that is OK, but methinks you'd quickly outgrow it if you intend to stay with radio control for awhile. Spektrum has a good 4 channel full range receiver for about $30 or so. Spektrum has one of the best warranties out there. As often as not, they'll repair your unit, and return it N/C. Even if it's out of warranty. Also, there are a lot of Spektrum clones out there, but as for me, I'll never put one in any of my models. Just personal opinion. http://www.wattflyer.com/forums/showthread.php?t=65573

As for ESC's, also a lot of good ones out there. As for me, I've been using the Castle Creations line for some 6 years, and 8 CC ESC's presently in my models. They all work very well.

Depending on the level of flying you intend to do, a starting point is about 100 watts per pound of airplane. Things get pretty good with 150 Watts per pound of airplane.

Again, here is where those computer program such as www.motocalc.com can help. Motocalc is free for 30 days, then $39. Motocalc allows you to put in your models wingspan, wing area, type of model, along with the motor, prop size, ESC and battery packs. Then motocalc will give an easy to follow text opinion on how the model will fly, and if you're overloading anything.

As indicated, there are also several other programs that do well, for zero cost. Castle Creations at www.castlecreations.com has one on their web site.
http://www.ecalc.ch/motorcalc.htm?castle&lang=en

FYI, it would be a good idea for you to locate a local RC club in your area before flying your model. Generally, these RC clubs have members that would be glad to check out your model before first flight. Plus, they may be able to provide instructions with a master/slave transmitter setup to fly your model. The RC instructor would handle the master transmitter, you'd handle the slave. Anytime you get into trouble, the instructor can instantly take over the model, and bring it back to a safe attitude. This master/slave radio system is one good reason to buy a name brand radio. Someone at the local RC field will be able to set you up with the instructor system. (Good luck with some off brand radio!)

As for help, check out these following wattflyer threads on what you are trying to do. Lots of reading here!

Hacker 6S2P A123 powered Models
http://www.wattflyer.com/forums/showthread.php?t=44686

Hangar 9 Kantana Model
http://www.wattflyer.com/forums/showthread.php?t=68844

Hanger 9 Twist 40 Model
http://www.wattflyer.com/forums/showthread.php?t=70548

AEAJR's Site on Electric Power
http://www.wattflyer.com/forums/showthread.php?t=18521

CHELLIE 12-03-2013 03:58 AM

Hi Technopro and welcome to Wattflyers, with the power system and electronics in your plane, your going to be at over 2 lbs, and a 53" wing span is going to have a lot of drag to it, IMHO you will need a 480 Motor and around 70 oz of thrust,

http://www.headsuphobby.com/Firepowe...otor-E-680.htm

http://www.headsuphobby.com/images/1...082258585.jpeg
Click To Enlarge
http://www.headsuphobby.com/images/1...119586098.jpeg http://www.headsuphobby.com/images/1...146220813.jpeg http://www.headsuphobby.com/images/1...808260131.jpeg

  • Item #: E-680


1


The Firepower 15 Sport (3542-10) is a 4.8 ounce, 960KV, 550 watt outrunner brushless motor that works well with 3 & 4 cell Lipo batteries. This motor is a good choice for many planes in the 2.5 to 4.5 pound range, and is especially well suited for '25 class' models.

We recommend using a 40A to 60A Electronic Speed Control (ESC) with this motor.

The Firepower 15 Sport comes with 3.5mm connectors installed and female connectors and shrink tube are included.
MOUNTING OPTIONS: The Firepower 15 Sport can be mounted in front of a firewall using the 3500 series 'X' mount and the 3500 series rotor end prop adapter, which are included with the motor. You can also mount it behind a firewall, and a 4mm prop adapter can be purchased to mount a prop on the motor shaft.

Propeller Test Data for the Firepower 15 Sport Motor:
It's a good idea to balance all propellers with a Propeller Balancer before using them on this motor.

Battery Size Propeller Size Thrust (oz.) Amps Notes 3-Cell 11.1v APC 12 x 6E 69 oz. 37 amps 3-Cell 11.1v APC 11 x 5.5E 56 oz. 27 amps 3-Cell 11.1v APC 10 x 5E 46 oz. 24 amps 4-Cell 14.8v APC 10 x 5E 72 oz. 38 amps 590 watts (avoid constant wide open throttle) Please be aware that the battery used can make a tremendous amount of difference in the performance of brushless motors. The above data was obtained using batteries in good condition that were fully charged. Thrust and amp draw may be less with the use of batteries rated at lower amp output, and slightly more using batteries rated for higher amp output. Other factors, such as ESC timing and variations in actual motor KV can affect the performance of brushless motors as well. We recommend the use of a Watt Meter to test the current draw of your particular power system, especially if you plan to use a prop that pushes the motor near it's maximum amp rating.
Firepower 15 Sport Specifications:
Weight = 4.8 ounces (135 grams)
Diameter = 1.4 inch (35 mm)
Motor length = 1.7 inch (42 mm)
Shaft = 4 mm x 0.7 inch (18 mm)
Voltage = 7 - 17 volts (2, 3, or 4 cell Lipo)
Current = 38 amps or 550 watts maximum for 60 seconds
KV = 960

pizzano 12-03-2013 04:23 AM

Curious what type of performance and flying style the OP intends to get out of this craft.....?.....He did mention he was brand new to flying!

If I'm thinking correctly, this is like an AT-6 Texan (Harvard) low wing WWII fighter......Certainly not a beginner model.........?

100 watts per pound sounds great......9.5 x 7.5 to 10 x 5 prop sounds good too.......that should get it up in the air with a 3c 2200mah.....just wonder what's going to keep it up in the air.......;)

AirmanAirhead 12-03-2013 06:01 AM

Technopro, the folks above know much more than I do regarding the type of motor, etc needed for your plane. I also have a hunch that for the most part they have been gentle in your comment "prob. will crash it within the first five flights.." And perhaps you have more experience than you are telling us.

But if you don't have much experience, Pizzano is correct, you need to start with a trainer and get some help, unless trashing the plane makes little difference to you. How I wish I had started out differently learning to fly than I did.:mad: I went through a lot of frustration, and crashed a lot of planes that were much easier to fly than what it sounds like you have. Finally a young guy in his 20's took me under his wing, and taught me how to fly. That's a much better way. But... you asked about the motor selection and not "is this a good way to start..." Soooooooooo nuf said.::o

JetPlaneFlyer 12-03-2013 09:22 AM

Quote:

Originally Posted by Technopro (Post 932996)
(brand new to flying and will probably crash it within 5 flights)????

Your right on that score, but there is no 'probably' about it. You could change it to 'within 5 seconds, virtually guaranteed'.

The Harvard is not a good RC trainer, dont try to fly it on your own. There will only ever be one outcome if you do and it involves taking the plane home in small pieces.

dahawk 12-03-2013 02:15 PM

Techno,

+1 on Jet's advice. and take it from someone like me who attracts NASCAR fans when I fly !

Hate to see you give it a whirl and then quit the hobby because you crashed your one and only plane.

Get off to a good start in this hobby. First, get your AMA card. Then start off with a high wing trainer like the Super Cub, Apprentice S, Sensei, etc. Do some buddy boxing if you have a club nearby or know someone experienced in RC. Get a simulator. You can find used Real Flight or Phoenix sims on ebay, RC Groups, RC Universe, etc.

The AT-6 Texan is not an easy flyer . Might be a third plane at best. I've flown the full scale version and the RC version. It can be a tricky plane. a torque rolling, tip staller. LOL If and when you do fly it, keep the speed up in the turns.

BTW, a wood/balsa/ cloth version at 53" WS is probably going to weigh more than 2# with lipo Did you say cloth/ What model is this?

Welcome to Wattflyer. a lot of really experienced people here like those who have commented above more than willing to dive in and help .

-Hawk

Technopro 12-03-2013 09:34 PM

To answer dahawk, This is a scratch build made by a guy who knows my grandpa. it sat in my grandpa's attic for at least 10 years.

Frame looks good and the fabric is in good shape. the material seems like what you'd find on actual T-6's. could be shrink rap.

I understand this will be a difficult flyer. I've got a trainer cub on my X-mas list and if Santa doesn't get me that I guess I'll take flying it very slow.

This will be my second plane. The micro Spit doesn't satisfy me, especially when the batteries keep blowing(not my fault).

So anyways, here's what I have found in terms of electronics. Opinions greatly appreciated.

Motor: http://www.headsuphobby.com/Firepowe...otor-E-680.htm

ESC: http://www.headsuphobby.com/Sky-Powe...-BEC-H-105.htm

Transmitter and Receiver: http://www.headsuphobby.com/RadioLin...iver-F-540.htm

Control surface servos: http://www.headsuphobby.com/Towerpro...ervo-B-520.htm

I live on a country airfield that is used maybe once a day in summer. My Dad owns an actual Harvard(NAT-6). Thought it would be cool to have a mini harvard to show with it.

Thanks guys!

dahawk 12-03-2013 10:03 PM

Techno,

The motor looks good but also check the Emax they sell or the power up 15. Both good.

Servos seem fine. Esc looks okay but look a the HURC line up they sell. They're good.

Headsup is an excellent online hobby shop.

The radio and RX are very lacking . That is , if you want to stay in the hobby past these two planes. Look at the Hobby King Turnigy 9x or Frysky 9x or a Spektrum . About the same price but don't come with receivers.

Hey, I have a Futaba 6EX http://www3.towerhobbies.com/cgi-bin...?&I=LXPZT8&P=7 I'll sell you and include a couple of Frysky "fasst" compatible receivers. This is quality stuff. Gives you some model memory and 6 channels in case you decide on a plane with retracts and flaps. I'd sell you this setup for $100.00 shipped. If you're interested , send me a PM.

You can also look on ebay or rc groups. I'd hate to see you get started with a a radio you're going to end up tossing. But nevertheless, it's great you are getting started !

Best,

Hawk

Technopro 12-05-2013 02:46 AM

Ok so what about this transmitter and receiver: http://www.ebay.com/itm/FS-2-4G-9CH-...50802535855%26

found this motor and esc:
esc: http://www.headsuphobby.com/HURC-30-...-ESC-G-148.htm

motor: http://www.headsuphobby.com/Emax-GF2...?categoryId=-1

servos are the same.
What about a propeller? keep in mine the current prop is 9" long and has 2" sticking out on either side of the cowl. Could someone recommend a prop that could work with this motor?

Thanks,
Techno

hayofstacks 12-05-2013 03:01 AM

the prop with that motor will be a 7-8" prop and likely won't work well. your looking for a 800-1100 kv motor about that size if you have prop clearance for it, I would recommend a 10-11" prop.

id get either the 450 I recommended earlier, or you could get a 480 plus or one of the 10 or 15 sized motors others have steered you to.

your on the right track with asking a lot of questions, but I wouldn't want you to waste a ton of money and end up with a bunch of toothpicks. either find a local club or flyer and get with them.

if you want to do it on your own, invest in a flight simulator. this will help you get the basics down and greatly increase you chances of success. if you were local to me, I would help you out and even let you fly on one of my planes to help you get the experience you really should have.

dahawk 12-05-2013 04:25 AM

Still not not keen on the radio. Don't know it. Kind of scares me. Get something that you can grow with, is supportable, has a wide range of rx options, and something others guys understand so they can help you. Not in any particular order but look at Spektrum, Futaba, JR, Hitec, Airtronics, Frysky/Turnigy 9x

solentlife 12-05-2013 08:09 AM

Quote:

Originally Posted by Technopro (Post 933173)
Ok so what about this transmitter and receiver: http://www.ebay.com/itm/FS-2-4G-9CH-...50802535855%26

found this motor and esc:
esc: http://www.headsuphobby.com/HURC-30-...-ESC-G-148.htm

motor: http://www.headsuphobby.com/Emax-GF2...?categoryId=-1

servos are the same.
What about a propeller? keep in mine the current prop is 9" long and has 2" sticking out on either side of the cowl. Could someone recommend a prop that could work with this motor?

Thanks,
Techno

The radio is the FlySky 9x ... same as the Turnigy 9x ... iMax 9x ... Eurgle 9x ... Walkera etc.

Best thing to do with it ... and I use 2 of these ... swap out the FlySky module and Rx ... replace with FrSky ACCCT module and Rx's ...

Keep the FlySky module as that binds with WLToys micro heli's if you ever want to try those.

See my signature and if you do get the 9x radio ... join us in the FlySky group ..

Nigel

solentlife 12-05-2013 08:10 AM

Quote:

Originally Posted by dahawk (Post 933179)
Still not not keen on the radio. Don't know it. Kind of scares me. Get something that you can grow with, is supportable, has a wide range of rx options, and something others guys understand so they can help you. Not in any particular order but look at Spektrum, Futaba, JR, Hitec, Airtronics, Frysky/Turnigy 9x

Hi Hawk ... the radio is the 9x ... it's factory label original.

Nigel

dahawk 12-05-2013 10:46 AM

Nigel,

I was hoping you would chime in. I get Flysky and Frsky mixed up but I know you're real happy with the 9X and of course it comes at a really good price. Techno ? listen to Nigel on this. Go with the 9X before you buy some completely unknown to mankind radio.

solentlife 12-05-2013 11:29 AM

The 9x will do just about anything you want - but it's not so user friendly in the menu ... the Chinse adaption of English leaves a bit to be desired ... and the supplied manual is crap !

But we have links to the better English manuals on the group - + all the help anyone needs.

It is ONE of the possibilities for radios ... others include DX6i (very limited compared to 9x - but a good entry radio) ... DX7 and above - which are really starting only to compete with 9x capabilities - but at far higher price tag. There are Hitec, Futaba, JR ... all brands have entry level / budget radios ...

The Radiolink - is very limited and also has mechanical trims - not digital. I have the 6EH for my 450 Heli .. flies fine on it ... but it really is old hat in todays market.

To be honest - I have just bought a 9xr ... even though I am very happy with my 9x's with FrSky.

Why ? Like everything - things evolve and 9xr has been out long enough now that most niggles are documented or solved. It's similar priced to 9x and has 2x the model memories, I don't need to reflash or add anything ...

I intend to swap a FrSky module out from one of my 9x's to the 9xr ... return the 9x to FlySky module for my Micro heli and possibly fixed wing as well - I have 2 FS 'B' rx's

Nigel

AEAJR 12-05-2013 10:00 PM

How do you know what size motor to use?

Everything you wanted to know about electric flight
http://www.wattflyer.com/forums/showthread.php?t=31368


How do you pick that radio?

How to select your first radio
http://www.wattflyer.com/forums/showthread.php?t=68741


Personally the low cost entry radio I would recommend based on what I read is the Tactic 650
http://www.towerhobbies.com/products...cj2650_bn.html



If you are looking that the FlySky TH9X, Turnigy 9X you may want to look at this thread.

9X - FlySky/iMax/Turnigy/Eurgle FOR DUMMIES
Quick summary that will explain a lot
http://www.rcgroups.com/forums/showthread.php?t=1616229


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