tom1968

Yes, right/down thrust works the same way with electric power as with nitro or gas.

Conveluted condor

Whats the formula /rule of thumb to acheive proper offset? I don't believe it's built in to the firewall on this arf.

Dr Kiwi

I dragged out some high school math from the '60's and found that for a 50mm wide firewall or motor mount plate, to get 3 degrees right offset, the left side needs to be ~2.6mm forward of the right. Obviously, for downthrust, the top edge needs to be ~2.6mm ahead of the bottom edge.

50mm*sin 3 = 50mm*0.052 = 2.62mm

Conveluted condor

So 3 degrees is the magic number? Regardless of motor torque? Thats it? I feel silly. I've built a number of kits and they all have the offset pre arranged when the fire wall is installed. Now I know. Thank you. Hopefully I can get this hot rod in the air before the snow flys and I have to mount ski's. lol

Dr Kiwi

I don't know if 3 degrees is "the gold standard" but it is a number I've often seen mentioned.

CHELLIE

Hi, The General Rule of Thumb with Electrics, is to use the same down thrust and right thrust that the MFG. recomends for a Nitro plane, and fine tune from there, Hope that helps, Chellie

celticflyer

YES

CHELLIE

Here is a little info on the bell motors, to help to keep them from spinning in the motor mount, and breaking the wires, hope that helps, Chellie

http://www.headsuprc.com/servlet/the...lectric/Detail

MOUNTING OPTIONS: A firewall mount and aluminum stick mount with heat sink are included, along with two prop nuts and a washer. Always check the tightness of all motor set screws and motor mount screws when installing motors. The motor set screws require a 1.5mm Allen wrench.

Some experienced flyers who post on the 'Wattflyer' forums suggest using a little 'JB Weld for metal' to secure the aluminum stick mount to the motor tube. This prevents it from working loose and spinning in the mount. Be very careful not to get any on the shaft and bearing though

Ellis1

Here's a simple mount using plywood and SS bolts and nuts. The thrust angle is infinitely adjustable.

Ellis

CHELLIE

Great Idea Ellis Thank you for adding to the Thread, Take care, Chellie

Kraft71

I'm new to electrics myself, but I don't think the type of motor (glow or elec.) would influence whether or not you need an offset. I think that would be a function of the airframe design, since the P effect is what makes offset necessary in the first place. Some airframe designs are more sensitive to offset than others, with tail draggers being the worst in my experience. I am putting a degree or two in the Cessna Cardinal I'm outfitting now. It's my first electric attempt, so we shall see how successful I am.

Merry Christmas!

Gale.

CHELLIE

Hi Gale what type of motor, esc, prop and lipo are you using on your cessna cardinal, Inquiring minds would like to know take care, Chellie

Kraft71

At this point, I am using an Emax CF2812 purchased from "HongKongFluie" on Ebay. Got an APC 7x5 electric prop and a couple of 11.1Volt, 2000MAH lipos to begin with, and an assortment of ESCs also acquired cheaply from Ebay Hong Kong providers. So far I have been lucky, and all of the vendors shipped promptly and the merchandise has been just as advertised. I am sure I will eventually get burned. Just won a nice Castle Phoenix 25 though, so may use that. Also bought a "Watts UP" wattmeter on the Bay and when it gets here, I will attempt to determine the best set up. LIke I say, I'm new to all this electric stuff, so have bunch to learn. The airframe is a Midwest Cessna Foam Cardinal I have had since the 1970s. ( 46" span, 290 sq. in. and 23-35 oz. ) Designed for .049 to .15 glow. These haven't been made in years, but they were among the very early original ARFs. Bought two, and used the original with a Kraft brick 3 channel with an OS 15 up front. Flew it on small fields and "schoolyards" for years. Still have the wing! With a .15, it was a strong performer. Added a hardwood spar to the wing for extra strength. Since I still have it, it must have worked, huh?

Fashioned a motor mount out of 1/8 lite ply, and got it installed last night. Still have to paint the moulded foam airframe, and install the radio. (Spektrum 7 probably, using full 4 channels )

I have downloaded a software program called "Motorcalc" I am sure all are familiar with except me. Mentioned it to the Electric guys at my local hobby shop (Graves RC) yesterday though, and they seemed to doubt it's accuracy. Anybody got an opinion? (Before I pay for it!)

Will update.

Here's the first Cardinal with the OS .15.

CHELLIE

Hi Kraft. the cf2812 is a nice little motor, but it wont be enough power for your Plane, may i suggest using this motor, and a 40 amp esc, this ESC has a 3 amp bec that will carry the electrical load of 4 servos, it will give you all the power you need, hope that helps, Chellie


http://www.hobbycity.com/hobbycity/s...r_(Eq_AXi_2808

http://www.hobbycity.com/hobbycity/s...eed_Controller




Input Voltage : 7.4V~11.1V (2~3S Li-po)
KV : 1400 rpm/V within 10%
Nb. of turns :22 Delta
Max. efficiency current : 10~15A
Current capacity : 22A/60s
Internal Resistance : 76 mohm
No Load current @ 7V: 1.19A
Dimensions : 35mm X 30mm / 1.38in X 1.18in
Shaft diameter : 4mm / 0.16in
Weight : 77g / 2.72oz
Number of poles/magnets : 14
Recommended model weight : 600~1300g / 21~45oz
Power equivalent : .12,2stroke

HXT 35-30-B 1400kv Tony McMichael

I tested this motor in a 650gr. built-up cessna with a W.S. 41" with a HXT D9 2200ma 3 cell LiPo. First prop which motor recomends 8-6, I used a APC E prop- W.O.T. readings start volts= 12.2 Amps= 30.9 V. drop= 10.8 Watts= 345.8 RMP= 10,822 50% throttle readings start Volts= 12.2 Amps= 11.5 V. drop= 11.5 watts= 134 RPM= 8200 Next I tried a APC 8-4 E prop W.O.T. readings start Volts= 12.4 Amps= 21 V. drop= 11.1 watts= 246.5 RPM= 12,831 50% throttle readings start volts= 12.4 Amps= 9.7 V. drop= 11.6 Watts= 112 RPM= 9,966 The paper work that came with motor claims 340 watts and can take 30amps, and they DID meet there goal. I have 2 of these motors and this is an excellant motor with a excellant price and would recomend it to every one! Awesome batteries also I might add!!! Thanks again UH!!

Kraft71

Hey Chellie.
Thanks for the good advice. I'm livin' and learnin'. I have a Mystery Pentium 40 Amp controller also and these other two motors:Mystery 3632-3500 and a KA22-20L Kv1050. Any chance of using this set up, since I already have it? I have just been accumulating a little gear, not really knowing what applications it would be suitable for. Appreciate your opinions. Thanks.

Krafty

CHELLIE

Hi Krafty the Mystery 3632 3500kv is to much rpm, you can only use a very small prop with it, or it will draw a lot of amps, the KA22-20L 1050KV is Perfect, direct drive, get a 3mm prop adapter for it, a 8" or 9" prop with a 4 to 6 pitch, should be fine, as it will take up to a 11x5.5 prop

the Mystery motor 3500 kv is good for a heli or you can use a gear box with a 3 to 1 reduction ratio, and use it in a plane, or you can mount a prop adapter to it with about a 4.7 x 4x2 APC prop, and use it Direct drive in a Funjet, or a wing. Hope that helps, Chellie

http://www.rc-sailplane.com.au/acces...l.php?accID=51

http://www.headsuprc.com/servlet/the...for-3mm/Detail

http://www.apcprop.com/cgi-bin/store...inc=6a&product=+

Kraft71

WOW! You're good! Thanks. Guess it's time to let the smoke out of this stuff and see what happens.

Merry Christmas

Krafty

CHELLIE

I have learned all of this info right here on Wattflyers, I am just passing on what I have Learned from Others Take care, and Happy Holidays to you and Yours, Chellie

Kraft71

HI Chellie,

Checked out your YouTube. Nice Katana. That you with the long red hair?? You're a chick!?? Shiver me timbers! Fooled me. How'd you get into modeling?

CHELLIE

Hi Kraft Yes I am Female I have been involved with Model Aviation since i was about 12 years old, I am 54 now, thank goodness i dont look my age Rc has keep me looking young I love this stuff, my father bought a pt 19 cox control line plane, and I loved that so much, i never left model aviation, Take care, Chellie

Kraft71

This hobby never ceases to amaze me, nor the people in it. I have met the nicest people in my 50 years of modeling. Wish I could fly as good as you! You go girl! Keep giving me that good advice! Got my watt meter today. Have to play with it a bit and learn how to use it. How about the Motorcalc software. Any opinion?

Krafty

CHELLIE

Since you have the Wattmeter now, I dont really think you need Motorcalc with bigger planes, keep your Motor KV at about 1000, with small foamie profile planes, a kv of about 1500kv seems to work fine, and if you want to go fast a inrunner motor of about a 2845 with a 2700 kv will work great for like a FunJet, Stryker delta, or a good size wing, with a 6x4 apc prop on a 3 cell Lipo or a 5x5 apc prop on 4 cell lipo, I have a FunJet doing 103 mph just ask a lot of Questions like i did and there are great people here that are very willing to help you out, Take care, Chellie

NAME: CHELLIE
SPEED: 103.00 MPH
PLANE: Funjet
MOTOR: 2845 HXT 2700kv
ESC: 80 Amp Turnigy
BATTERY: 4 cell LoongMax 2500mah 30C
PROP: 5x5 APC

http://www.wattflyer.com/forums/showthread.php?t=26852

LectricPlane

Here is one I just put together for my PZ Spit.
Pics below.

12mm Balsa rod push formed into a 10mm hole in the ply firewall, the rest is reasonably clear in the pics, I think.

The through mounted balsa standoffs make it easy to set the angle and length.

Can't wait to get it in the air!

Destroyer of airplanes

This is how I did it on my GWS P-40. This system makes it simple to set the down and right thrust and precisely align the spinner and cowling.

Paul

CHELLIE

Hi Lectric Plane Hi Paul nice Looking motor mounts, Thank you for sharing, Chellie