Sig Kadet Senior~how much power?
I'm doing my first build since the 1970s. I'm taking my time and really enjoying building again
I am building a Kadet Senior and I will convert this plane to electric. The outdated instructions (1985) that came with the kit state this plane will weigh around 6 pounds when completed and I assume that was with a fuel motor and tank.
I was thinking of a power plant in the 46 range with 700 to 800 W. I would think that this would be more than adequate for the Senior.
I would like to get 8-10 minutes (or more) of flight time with his plane and I was thinking that a 3000-4000 mah battery would do the trick.
And my about right with power and battery for what I want to do?
Also for those that have already done this, where did you put your batteries hatch? I am just not sure at this point where weight should be in this build.
Rule of thumb for a trainer is 100W per pound. Yes you can go lower but what does lower get you? You have to run the motor/ esc/ battery/ and prop as a system. If you have a motor that has a certain physical size it can not handle more than a certain amps or watts. Then you have to think of what size prop will have the motor operating in the proper band of these amps and watts. The kV of the motor adds into this as it is the rpms per volt.
Equivalent to a 30- to 36-size glow engine for sport and scale airplanes weighing 3.5–6 lb (1.6–2.7 kg)
Ideal for 25- to 36-size 3D airplanes up to 4.5 lb (2 kg)
Weight: 200 g (7.0 oz)
Ideal for models requiring up to 800 watts of power
Recommended Prop Range: 11x7 to 14x10, (10x10E tested on 5S in Sundowner 36)
Voltage: 12–16.8 Cells: 3–5S Li-Po
RPM/Volt (Kv): 770
Continuous Current: 42A
To keep things simple if you have a 32 sixe motor that at it's max puts out 800W. (The web site says it'll do 800 but to be honest I just don't beleive that) That is good power per weight. Now lets look at what it takes to get that motor to that power. First W is A times V. W is Watts, A is Amps, V is Volts. All are capitalized since they are the names of people.
So to get 800W on a 4s pack (14.8V) you are at 55A (note that exceeds their 42A max current). So lets run it at 5s, we get 43A. Lets plug these numbers in a calculator. To run 800W, 43A, on a s pack and use a decent large diameter low pitch prop we come up with a 11x5. This also shows a pitch speed of 61mph and 111oz of thrust. Experience tells me you'll get a max speed of about 55mph and 110oz of thrust though. Also I would say 12 minutes of flight on a 5000mA battery. Is this enough for you? You'll have to be close to full throttle alot and 5.5lbs of thrust will fly it but again you;ll be at full throttle alot.
Now lets look at a bigger motor, we'll stay eflite and go with the power 60. 400kV, weight is 13oz, up to a 10lb plane, 1700W (still don't beleive that), 55A current, 14x8 to 16x10 prop range. But instead of running it full power lets prop down. A 15x8 prop on 6s gives 44A, 940W, 57mph, 150oz thrust. Realistic on your plane will be 52-53mph and 140oz but you are no where near the max power of the motor so it'll stay nice and cool and even at this power level you have more power than you need so you'll fly more at 1/4-1/3 throttle. What does all that mean? More flying time. Yes it is heavier, 6oz heavier motor and a bit for the 6s VS 5s but it will run so much cooler, you'll have longer flight times, and look at the props. 11x5 VZ 15x8, which will be more efficient on you're larger plane?
Eflite is a quality motor (as I told you) but with a 32 you'll be running it at max a lot more. it costs $75. Lets take a look at what I have on my 6.5lb Quaker old timer. A similar spec motor as the Power 60 but from Hobby King for $27 (not sure of current availability or price). Yes heavier but I run it at a much lower power setting than I would a smaller motor, the weight doesn't mean anything on my plane and I have extra power if I want it. And it was much cheaper...
This is why I recommend a E Flite 60 on the sig Kadet senior, more flite time and CG Balance, chances are you wont have to add dead weight to get the CG Right, but a 32, 46 ,or 50 will fly it well too,
Battery Hatch Ideas
In the meantime, I dug these shots up from my take of the 2006 CASA Spring Sizzle here in MD. The model's a kit built LT25 from VA's Tyler Ake, but the 'technology' should be applicable to any Kadet with a little shuffling.
this might give you some ideas on a battery hatch
Thanks for all the information.
When looking at the ratings on many 46 class motors I noted the various outputs of the motors with different props in place. a 60 size?? Wow, that should give really short take offs!
Not having completed this build I don't know how much clearance I even have for the prop at this point.
I am a fan of big blocks in the old days in cars and do prefer something that has reserve power.
In this application I don't really think that I will be drawing all that much power unless I want a grass takeoff on my soccer field that is just 2 blocks away. So yes cooler is better and I don't believe in stressing components.
TNX for the link on the hatch too. I was thinking that the bigger battery is going to have to go more to the rear than some of the smaller planes I have had in the past.
and some more ideas :)
Well, there you are..... another Seniorita. I had to rebuild a new fuse for the Arf after a battery connector went intermittent, so I purchased the fuse kit from Sig and the wing and tail structures mated onto the fuse with no problems. I use a Scorpion 3020-12, CC. ESC and 3-4 S pack. I also replaced the wire landing gear with aluminum and use DX Spectrum receiver . I have a kit built Seniorita that is going on floats. When I built that one, I made the battery hatch on the top of the fuse instead of the bottom and I also reinforced the fuse for the extra float attachment.
A lot of people might balk at building one of these from the kit but I assure you it will be a fun build and you can modify to heart's content. I did add ailerons to the wings as the original Seniorita is a 3 channel plane. If you want to add flaps it would be no big deal but I really don't see the need for them. I've seen them on the Kadet Senior as it is a larger plane.
I am not planning on adding flaps to this one.
Other than the mods for the electric conversion this will pretty much be a stock plane.
I have seen a number of the Senioritas fly and liked the way they flew and understood that the Senior flies even better in the winds.
The pix that you provided in the links reminded me that I am going to have to consider vents for the cooling of components too.
and just some more ideas :)
Sig Senior Recomendations Anyone?
I just placed an order for a Sig Senior Kadet kit. That's right, I said kit. I want to make some modifications to it to make it a little more sporty. Here is what I have in mind:
Drop off one wing bay on each side
Cut the dihedral angle in half
(I'm hoping these will improve the roll rate)
Split the elevator, move the fin and rudder rearward and extend the rudder all the way down to the bottom of the fuse.
Make make it a tail dragger and give it bolt on wings.
Obviously, I'll be adding a battery hatch somewhere, but I'm not sure about where it will be just yet. I'd like it not to be on the bottom if I can help it. I hate having to flip larger planes to change batteries.
If you have any other airframe modifications that you like for this plane I'd love to hear about them.
Power system will be what I now resides in my Somethin' Extra, which is...
Hacker B50-13S 5.2:1
TP Prolite 4S3P 6000 mah (This should be good for some really long flights)
Phoenix 60 ESC
I'm basically building this so that I'll have a good plane for flying touch-n-goes. Sometimes I just like to fly those over and over again, trying for that perfect landing and practicing side slips. I also want it so that occasionally I can plug in a buddy box and give a neophyte a crack at the sticks. I've been wanting a plane like this for a long time but never made it a priority. This building season that procrastination comes to an end.
I'm sure nobody needs to see a full construction thread on a simple trainer but I'll probably be posting some progress photos every now and again.
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