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Reformed Nitroaddict
07-19-2005, 07:43 PM
New to RC Electric flight? Have a question that needs answered about the basics? Post it here!

No question is too basic, leave your concerns at the door!

TNB
07-27-2005, 05:21 AM
Hi Nitro! I'll post a few if I get around to getting one of those hydro-foams. ;)

Reformed Nitroaddict
07-27-2005, 01:52 PM
Fantastic Tigger.

Someone here just finished one and brought it in the LHS to show off the other day. I cannot wait to see it fly/drive/swim?

TNB
07-28-2005, 06:01 AM
If I can use my Nomadio Sensor transmitter, it would look like I was fishing for hydrofoam. ;)

Reformed Nitroaddict
07-28-2005, 12:27 PM
Haw. Not quite sure if you need to add even more attraction at the lake. A flying boat should suffice nicely, lol.

Geoff
07-30-2005, 03:56 AM
Being an electric "virgin," perhaps I should have gotten a kit, but I wanted something else, so I'm building a 36" span bird with a guesstimated weight of 350 gms. I have a Maxx HA 2015/4100 geared motor/ Castle Creations Phoenix 10 ESC and a Tanic 2 cell 1550mah li-po. I'm NO good with motor power calculations, but I'm guessing that I'll need to use three cells to get the rpm to spin a small diameter prop. I want to keep the prop somewhere near scale-like dimensions. What do you say I need to do to be successful - besides going back to castor oil and glow plugs, that is!

Reformed Nitroaddict
08-01-2005, 03:00 PM
Geoff - welcome! In general, the easiest way to check out prop size and how it will work will be to download a copy of www.motocalc.com - its free to try for a month. For the 2015 motor, you really need to be careful not to over amp it. It likes to spin around 9-11amps continuous, so that being said, anything larger than a 10x7 on 6:1, 9x7 on 5:1, or 8x6 on 4:1 will send it to it's limit. These figures would be on 3cells however, and you have alot more margin for error on 2.

For really spirited performance, you would want to produce about 70-80watts of power for a plane of your size and weight. Just to give you a baseline, my 2015-4100 on 5.33:1 gearing spinning a 9x6prop with a 11.1v 3S pack is pushing about 95watts.

Does any of this help?

Geoff
08-02-2005, 03:18 AM
These figures would be on 3cells however, and you have alot more margin for error on 2.



Does any of this help?

Thanks! But now I'm confused in a different way. How would I have MORE margin for error on two cells than three? It's been a long time since I fiddled with the power formula, but it seems to me that if the motor were pulling 90 watts on two cells, it would be drawing MORE amperqge than if it were drawing 90 watts on three. So where's the greater margin with two vs. three? I hope you'll bear with me if this is just too dumb a question!

petej
08-02-2005, 03:38 PM
Geoff:

Maximum motor current for a brushless drops with a lower voltage source. Since watts is the product of current X voltage, as both current and voltage drop, watts drops, too.

In other words, motor wattage is not a constant -- the motor changes characteristics depending on voltage and prop size.

Motor current is very much affected by load, which is why prop size is a balancing act. You can see how these variables work in the Great Electric Motor Test here:

http://www.flyingmodels.org/index_en.htm

Geoff
08-03-2005, 03:01 AM
NOW I see the light! Thanks, PeteJ! Now if I can see why the computer programs like Motocalc are so useful!

PhilipShum
08-08-2005, 03:40 AM
Dear Nitroaddit (Reformed),

I have read the "6 Keys to Success" and hope to put it in practice.

Before my Electric Plane is taking off, I have a question about ESC settings and would like to know more.

It is concerning the Throttle Curve, the ESC I am using can be set to linear or logarithm. What is the difference between these two settings and how would the Motor re-act ?

I should be grateful if you would enlighten me.

Philip SHUM

Mike Parsons
08-08-2005, 01:57 PM
Dear Nitroaddit (Reformed),

I have read the "6 Keys to Success" and hope to put it in practice.

Before my Electric Plane is taking off, I have a question about ESC settings and would like to know more.

It is concerning the Throttle Curve, the ESC I am using can be set to linear or logarithm. What is the difference between these two settings and how would the Motor re-act ?

I should be grateful if you would enlighten me.

Philip SHUM
Philip,
Welcome to Wattflyer. What ESC are you using and what are you using it in? I have never seen an ESC that gives those two choices. Usually you have an Auto Calibrating (aircraft), Fixed (fixed pitch heli's) and governer low and high for helis as well.

Mike

PhilipShum
08-08-2005, 05:04 PM
Dear Mike,

Thank you for you reply.

I am using a JETI Advance Plus speed controller for brushless motors. I use an Out Runner Motor and it was installed on a Cessna EP. I am also using the JETI Advance plus Prog-Card for setting up the said ESC.

Whilst test fly the Cessna EP, when taking off, the side thrust seems too strong. I have check the down and right thrust of the Motor alignment, seems OK. Therefore, I expolre on the ESC Throttle Curve settings. I do not know whether the ESC throttle curve selection would sort out the porblem or not.

May be you can advise me further.

Philip

Mike Parsons
08-08-2005, 08:19 PM
Philip,
I have to regress. I have used the Jeti Plus as well and never realized the language on them. You want to maintain the default setting of Linear. This setting divides the power evenly along the entire throttle stick range. So half throttle is 50% of maximum RPM. Logarithmic will give you most of your throttle range before you reach half throttle. (Half throttle is equal to 50% of power or 71% of maxium RPM)

I think you have some other issues going on with Side thrust. What is are the symptoms it is exibiting?

-Mike

PhilipShum
08-09-2005, 01:48 AM
Dear Mike,

Yes, I think I should maintain the linear throttle curve setting in order to give a even power output to the motor.

The symptoms was while taking off, the Cessna bank to the right side suddenly just like 'Right Aileron' was given.

If the 'Throttle Stick' was not pushing too hard then this symptom is not so obvious.

I do not think it is the 'finger' accidentlally giving alieron whilst giving throttle. Because it was not me (Novice) doing the test flight. The test flight was conducted by an experienced flyer in my club.

Philip

Mike Parsons
08-09-2005, 06:10 PM
So it is rolling right and not yawing to the right. Yawing or pulling to the right could be a symptom of too much right thrust. Rolling in one direction or the other is usually either a deflected surface (not trimmed) or the tail plane surfaces being off. Move to the rear of the plane look at the elevator in relation to where the wings are. Are there equal distances between the control surface and wing?

PhilipShum
08-10-2005, 01:40 AM
Dear Mike,

Your findings are spot on. Thank you very much and this would no doubt benefit me a lot in my future model plane building.

As directed, I have check the tail plane surfaces and it revealed that the tail stabilizer is not exactly parallel to the Main wing.

Philip

Mike Parsons
08-10-2005, 09:00 PM
I am glad we could find the problem Philip. Keep us updated on your progress!

-Mike

PhilipShum
08-11-2005, 03:07 AM
Dear Mike,

Thank you again for your advice.

Philip

Spectrepilot
08-20-2005, 10:54 PM
You guys have a wonderful forum and largely due to the reading I have done as a lurker on here, Iíve decided to give electrics a try. Iíve been a nitro RC flyer for a long time so I have a few questions as I make the leap.

Iíve decided I want the Tensor 4D and I am going to list the equipment I think should go with it but would appreciate any input you have.

Obviously I am going with a Lipo battery and one of the guys at the club recommended a 730 MAH to go with a park 370 motor and a 10x6 prop. Additionally, I was planning on using the Jeti 8 ESC. Much of this equipment is new to me so I am going to list the prices in hopes that you can provide some feedback on my choice and perhaps tell me a good place online to purchase electric gear. I think my local hobby shop has reasonable price and will get at least some of my gear there is the prices are close.

Tensor 4D $54.00
730 MAH Lipo $42.00
Park 370 Motor $49.00
Jeti 8 ESC $69.00
ESC program card $7.95
Light Receiver $30.00
Crystal $10.00
HS-55 Servos $25.00 Each
Lipo Charege $45.00

Does this gear make sense to folks who have been doing this for a while? Any recommendation for online places to purchase these items?

Again I want to thank the folks on this forum for sharing you time and knowledge, Iíve tried to read and search as much as possible before I ask my questions so as not to waste your time. I appreciate your inputs.

Reformed Nitroaddict
08-21-2005, 12:15 AM
You are on the right track - but some things to consider:

The ESC, Motor, Battery combo you choose should be as flexible as possible, so that if you trash the plane or get bored of it, you can swap it.

The Park 370 is a good motor, but you may want to consider the Park 400, as it will give you more options due to it's larger power curve, but the 370 is okay too.

The Jeti ESCs are good, but very expensive. You can get many other ones for alot less money, and again - go with a higher amperage esc, so that you have more versatility - 8amps isn't very much. The Castle Creations brands have a great following, and you can get a 25amp CC esc for almost the same amount of money. The Eflite 20amp ESC is also great, and it's only 41.00.

Finally - whatever batt you choose - make sure that it is a 3S pack and make sure it can handle the amps you plan on setting up the plane for. Use www.motocalc.com to verify amps and power output.

Which receiver are you planning on using? 30.00 seems cheap.

And at last - buy the best, most expensive charger you can afford - trust me, you will wish you did later on. The Triton and the Astro 109 are both about 120.00 and will last forever.

Spectrepilot
08-21-2005, 12:55 AM
I don't remember the brand of the receiver, but several other folks in the club have them and seem to like them.

Can you recommend a few sites for purchasing the gear you mentioned? I've used Towerhobbies and Horizon for some of the nitro stuff, but I was hoping there might be a better site that deals with electrics. I thought for sure there would be a few battery wholesalers?

Thanks for the feedback

PhilipShum
08-21-2005, 01:16 AM
Dear Spectrepilot,

I am a novice in RC flying.

Since you have been flying nitro RC for a long time, I am afraid that the proposed set up with power supply limited by an '8 Amp' ESC may not satisfy you for long.

You might have to invest more $ to up grade fairly soon.

Philip SHUM

Reformed Nitroaddict
08-21-2005, 01:30 AM
spectre - great places to buy electic gear:

www.atlantahobby.com
www.gwsexpert.com
www.hobbylobby.com

Those should get you started.

Spectrepilot
08-21-2005, 01:43 AM
Great feedback all. I've been checking out the sites you provided and the prices are indeed better. Refromed Nitroaddict, you mentioned mentioned the park 400 motor, would you recommend the 740 or 920 KV. I presume the 920 draws more power and will give a bit more torque?

Reformed Nitroaddict
08-21-2005, 04:42 AM
Sure - the 940 will produce more RPM.

Another great outrunner is the Hacker A20-26M - about 17oz of thrust when propped for 12amps.

funnysticks
08-26-2005, 04:41 AM
Being new to E-flight and and old time r/c flyer, I went to my local hobby shop and He helped me pick out a combo that would be able to fly from my backyard. I had not flown in 8 years so I went with a trainer type. I am very impressed wth E-flight. Plenty of power and great flight times. and no noise or cleanup. I highly recommend any one to give it a try. I used the E-Flight brand plane the Gypsy with the 370 brushless and 20 amp esc. on 2cell 1300 lipo's from Thunder Power. I also went with the Celectro lipo charger. This is not a commercial, Just a happy 68 year old r/c nut. I also have a mini Funtana waiting for me get up the courage to fly. It is ready to go as soon as I get my confidence back after my long layoff. Thanks for a great forum to bounce Ideas and comments around. --Dan--

doctoro
08-28-2005, 04:36 PM
does anyone have any info on wattage sport bipe?

Chris44
08-29-2005, 12:00 PM
I think senility:confused: has set in at 55. I cannot get my mind around the 1c charge rate of a battery.Is it as follows:

Q1....2,000 mah..3 cell..11.1v..15c....safe to charge at 1.5 amp

1,050 mah..3 cell..11.1v..c?......safe to charge at 1 amp

1200 mah..2 cell..safe to charge at 1 amp

Q2....What does 15c on a battery mean

Regards
Chris

PhilipShum
08-29-2005, 01:59 PM
Dear Chris44,

I do not think there is anything to do with age. Please refer to post #27 from funnysticks, he is 68 years old and looks very ambitious.

By the way, the 2,000 mAh, 1,050 mAh and 1,200 mAh mentioned in your post is referring to the capacity of the battery. While 15C means the battery is capable of providing 15 times the current of its capacity continuously, for example, the 2,000 mAh battery you have mentioned at 30 Amp.

Some battery do better and some does not. For example, some with only 6C and some provide 20C.

Charging of Li-po battery should not be more than 1 C, for example, the 2,000 mAh battery at no more than 2 Amp.

Philip SHUM

Chris44
08-29-2005, 02:31 PM
Thanks Philip,
I appreciate your explanation.:p I understand know.

Kindest Regards
Chris

big daddy
08-30-2005, 04:07 AM
Dan I'm from KY also, Go Cats! Where did you pick up that charger? cant find one to check out specs as I'm in the market for a new one. how long does it take to charge your packs? How much did it cost?

Twmaster
08-30-2005, 04:44 AM
Something worth mentioning here. All chargers will take about the same amount of time to charge your batteries when set to the same charge rate. In other words, 1A of charge rate is 1A of charge rate.....

Trying to put too much juice back in the pack (fast charging) is not always a good idea. As pointed out above different cells have different charge rates and discharge rates they can sustain. For example Lipo cells go boom when overcharged. Nicad/NiMH get hot and die (or burn up in extreme cases).

There are a lot of good chargers out there in the marketplace today. Ask 20 flyers get 30 different answers!! :)

For the record I use two chargers. My Nicad/NiMH charger is an E-Flight Pinnacle (http://www.redrockethobbies.com/product_p/eflc2015.htm) and my Lipo charger (as yet unused) is a Great Planes PolyCharge (http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXHNW5&P=0)

Tioli
08-30-2005, 07:22 AM
Hi all, I have an ESC question: If a kit or motor recommends an 8amp ESC for a certain application, can I use a larger ESC in order to give me flexibility later on? ie, in case I want to use the ESC in another plane. What are the draw backs of using a larger ESC than the motor calls for?

Geoff_Gino
08-30-2005, 08:29 AM
Hi all, I have an ESC question: If a kit or motor recommends an 8amp ESC for a certain application, can I use a larger ESC in order to give me flexibility later on? ie, in case I want to use the ESC in another plane. What are the draw backs of using a larger ESC than the motor calls for?
Hi David

Me again, yes you can, the rating on the ESC is the max it can deliver without damage.

Geoff

funnysticks
08-31-2005, 04:11 AM
To Big Daddy, If the question about the charger was to me, The Celectra charger is available from Horizon Hobbbies. It is by E-flite. It will charge 1 to 3 cells at 2 amps,1.5, 1, 500ma. and 250 ma. I think I paid about $45 for it. I like it because it is almost Idiot proof. It also has an audio notification for a completed charge and completely cuts off charging.
This is very important for lipo's. Danhttp://www.wattflyer.com/forums/images/icons/icon6.gif

Tioli
08-31-2005, 04:19 AM
Thanks for the battery and motor info, Geoff. I have it in my shop next to the motors/esc/batteries...It does make sense. I have had to re-read it several times, but that's just me...

Tioli
08-31-2005, 04:21 AM
funnysticks, I use the celectra too. It really is a great charger. I made adapters so it'll work off a wall wart, a 12V battery, and the cigarette lighter in my jeep.

PhilipShum
09-02-2005, 01:07 AM
Dear David,

(#34) referes. I think the draw back of using a larger ESC than the motor calls for are : first, you have to pay more $ for your initial investment and second, it might weights more and has larger dimensions.

Philip SHUM

falingtrea
09-05-2005, 06:40 AM
I'm a little confused. What is an outrunner motor and how does it differ from a regular brushless motor? And is there such a thing as an inrunner motor?

petej
09-06-2005, 01:13 AM
Outrunner motors spin the outer case of the motor, rather than an internal armature. The result is a motor that runs more slowly with more torque than an equivalent conventional brushless. They also run cooler. Outrunners are often used in place of geared motors.

TNB
11-03-2005, 04:29 AM
Haw. Not quite sure if you need to add even more attraction at the lake. A flying boat should suffice nicely, lol.
While demo'ing cars at iHobbyExpo--I took the plunge and purchased a micro heli, a large scale boat, some minis, and so on. Planning on doing a little lunch time "learning to fly". I also checked out my friend's hydrofoam but I never had a chance to see him fly it. Maybe next time.

Geoff
02-26-2006, 10:22 PM
Does anyone sell light weight "Y" harnesses with a servo reverser on one side? My little scratch built project will need such a setup since I'm using convential (scale-like) ailerons, with Blue Bird BMS 303 servos. Too late to simply turn one servo around, since they're already installed. :(

TIA,

Geoff