Electric Top Flite Giant Corsair
I have the Corsair kit in the process of being built and had run into some questions. It is supposed to end up weighing between 24 and 26 pounds. This is what I have planned on using for all of my electronics:
-Rimfire 65cc (will probably use the recommended prop)
-Castle Creations Pheonix Edge 160A HVF
-X2 6s 8000mah lipo in series
-X8 HD-1501MG servos (Troy Built Models)
-Spektrum AR6210 receiver
I am fairly new to the hobby and I am still learning so any help will be greatly appreciated.
My first question is basically...will this work? If not, what do I need to change? My second question is...with these servos and receiver, will a brown out occur? I've heard about servo voltage boosters but I am unsure if that will help this potential problem. I just want to take the necessary precautions to make sure I will not loose this plane due to an electrical problem. Again, thank you for any possible help.
Ive had very poor luck with those HD servos. I would hesitate to use them in any model I cared about - or in anything at all actually. They center terribly, use a LOT of power and fail easily.
I would highly recommend you use quality servos. Hyperion, Hitec or Futaba digital servos would be an excellent idea.
Id also use a separate 10 amp BEC or 10 amp regulator with a separate hi capacity rx battery pack - like an A123 or 2 cell lipo pack for example - for receiver power and disable the internal BEC on the Castle if it has one.
Large heavy war birds need extra attention paid to the components you use. They are expensive to crash and dangerous if they get out of control :)
Hi :) Rimfire motors are a funny motor, they normally dont like other MFG ESC, Due to Motor to ESC feed Back Issues, use a Silver Series ss-120 ESC made by GP.
Also with Giant RC Planes, Its best to use a Large Separate Receiver Battery Pack for Safety
REQUIRES: Speed control for Brushless Motors such as the ElectriFly Silver Series SS-120 Propeller: 22 x 10- 26 x 12 (due to the high torque and high RPM of this motor the use of electric-only propellers is not recommended)
I just ran the 65cc motors numbers through www.motocalc.com. Motocalc suggests that actually running this motor at its "Rated" power level will burn it up in short order. Motocalc suggests this motors windings will hit 400 degrees F at only 60 Amps input to the motor. And at this power level, the motor is only about 70% efficient. That is awful.
To me its always a concern when the motor mfg does not supply their motors winding resistance. That is a critical factor on how efficient their motor is. One figure I found for the 65cc winding resistance is 0.066 ohms, which is a very high (bad) value for a motor of this size.
As a comparison, my Hacker A60-16M motor which is one half the weight of the 65cc motor has 1/3 the winding resistance. Running my Hacker A60-16M motor at 78 Amps results in an efficiency of about 89%. I've got two of the Hacker A60s, and both of them are very cool to the touch after a hard flight. Both are pulling about 80 Amps at full throttle.
My A60 motor is installed in a 17 pound model, and I'd be very reluctant to put it into a 22 pound model. Hacker makes a variety of A60 sized motors. Their A80 motors will put out 7000 watts, but those are $$$$$$ motors.
As for the receiver power system, IMHO, in this size model, dual receiver/servo power is mandatory. That power supply can consist of the Castle Creations 20 amp switching type BEC, along with a two cell A123 battery or a two cell LiFe battery. The battery must be isolated by a pair of 10 Amp silicon diodes. I've got plenty of wiring diagrams if you need them.
The Hacker A60-14L motor is only rated at 3500 Watts, and might be a bit small for your model: That would be about 150 watts per pound of your airplane, which is still pretty good.
The Hacker A80 series motors will certainly do the job. But their price tag. Big OUCH. And, you need to own a LiPo battery factory.
Open up www.youtube.com and run a search for Hacker A80. There will be a number of models with this power system, and none of them are underpowered.
Take a look at my stuff so far:
Giant Scale Power System:
Battery Backup System
Carl Goldburg Extra 330 Electric Conversion
Giant Scale electric motors vs Gasoline Engines
Harbor Freight Gasoline/Alternator Setup
Great Planes Giant Big Stick Electric Conversion
Giant Scale Cessna Model
Redwing MXSR Model
As can be seen, electrifying giant scale models gets expensive very quickly. IMHO, about 1/3 of the total cost should be the model, 1/3 for the radio and 1/3 for the power system. That rules out cheap bottom of the line components, in my opinion. For giant scale models, it's just not worth it.
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