patterndreamer

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Hey guys let me know what you think of this build thread. I hope to do more, but just need to know what I can improve on.

Introduction:

This conversion has been done a few times, but I thought I’d give my own version of it and maybe help some of you out there make the decision to try a glow to electric conversion. The Kadet Senior is a plane that has been in existence in one form or another for 30 years,
a staple of the R/C hobby. So, what brings a guy to a plane that is older than him in design, maybe it was the ease of build and light wing loading. This review will cover the conversion of a Kadet Senior ARF to electric and outline the process of installing the power system. The assembly of the plane should be easy enough for those considering this conversion and there are plenty of other articles that cover the construction of the nitro-version Kadet.

Materials:

The first decision was what motor I should go with for this project. The obvious choices included the Axi motors and the E-Flite 46, but in the end I chose the Common Sense RC E46-4 motor for its relatively inexpensive price and for its performance based on their smaller motors that I have flown before. Next comes the ESC, where I again went to CSRC and picked up their Z-75 OPTO speed control. I decided not to go with the BEC because of my own preference for having a separate battery to power the receiver. And, to keep the idea of comparatively low cost going, I finished off the power package with a CSRC 14.8v 6000mah budget pack. These packs are
inexpensive for their size, although they don’t exactly have the same current rating of your typical Thunder Power or Flight Power battery. For a motor mount, I picked up the Great Planes Large Electric Motor Mount because it lined up perfectly with the motor and was one of the easiest ones I could see to mount without building a motor mount box.

Building:

I already had my Kadet assembled and waiting for its new power plant. The first step is to check all your components and get any connectors you need soldered up and ready. I made sure to check all my equipment before I placed it in the plane. This is easy enough and should be a good precaution to take with the assembly of any plane. After checking everything, I looked at the plane and figured out how to get the holes lined up for the motor mount. I centered the mount over the hole for the fuel tank. This helped me find the centerline for the prop as it lined up perfectly with the center of the opening.
I continued on and marked where I needed to drill my holes for the mount. I started with a small drill and worked my way up until the holes were big enough. Then, as you can see in the picture, I used a small magnet and put the blind nuts on as shown. This made it much easier to reach in to place the blind nuts. I then pushed them into the hole and used a screw to help it dig into the wood. I did this for all four holes and made sure to use a bit of epoxy around the nut to hold it in.
I then simply went ahead and mounted the mount on the plane. I made sure to use Loctite on the screws as I put them in. I then finished mounting the motor. Next up was to get the cooling holes made and mount the ESC. I found I had to make extensions for the ESC so that I could easily hook up the battery without needing to make a hatch in the bottom of the plane. For the extensions, I used another set of bullet connectors and about four inches of black and red wire, as well as some shrink-wrap.
The next step is to secure the battery. I’m using a Velcro strap setup for mine, but you are welcome to use whatever you prefer.

Flying:

The Saturday after I finished the conversion happened to be perfect for a first flight, so I packed it up and brought my cameraman (my dad) along to get some pictures of the occasion. I did my typical check of the plane before setting up everything and heading out the flight line. The CG was right on with the battery directly beneath the recommended CG.
The plane taxied well under its own power out the runway and tracked well as I throttled up to take off. The plane took off within about 150ft and slowly gained altitude as the electric motor whirred away. I brought the Kadet to about 300ft and flew it around for about two minutes before I decided to change props. I felt that the motor could provide a bit more power than the prop on it was producing. The plane came around to land, but it needed to be forced down from its glide to get it to come down onto the runway.
While I had the plane on the worktable, I made sure nothing was loose and everything seemed to be right. Then I proceeded to switch from the 13x8E prop and went to a 13x10 regular prop. Taking the plane off again, I could notice the increased pull but felt the motor could handle more, but went ahead with my flight anyway. As the flight went on, I occasionally gave the plane a bit of a blip in power and it would immediately respond, thanks to that electric motor.
Fifteen minutes later, I felt it was time to come down and once again forced the plane down and finally stopped it after it rolled out for another 200ft or so. I didn’t have a charger on me to check the mAhs that would go back into the battery, but the voltmeter provided a good gauge of how much more I could have flown. After roughly seventeen minutes of flying, this is including the previous short flight; my voltage only read an average of 3.8v across the four cells.
On another flight the following Monday, I flew for around thirty minutes with my dad on buddy box. Managing the throttle the whole time, my average voltage afterwards was about 3.4v, which I figure would leave me with another five minutes worth of flight time.

Conclusion:

The Kadet Senior has always been famous for its easy flying characteristics and slow flight. The CSRC setup brought this design up to date and has given the Kadet that seamless you couldn’t get with the glow-powered version. The immediate response and long flight times makes the setup a great alternative to the typical glow engine. The downsides are the cost, the required modifications to the plane, and the charge times between flights if you only have one battery. But, for a first time flier who wants to fly a big electric, or the experienced pilot who feels the need for that one fun to fly, no hassle plane in their fleet, I would recommend converting the Kadet Senior to electric.
The CSRC setup was easy to setup and contributed favorably to the flying style of the Kadet. The motor and ESC are priced competitively with the E-Flite line of electric equipment and a bit below the price point of the equivalent Axi and Atlas motors. The battery was well suited for this application with an amperage rating perfect for its intended application. You could use smaller four cell batteries or even up to a six cell with a high current draw, but I feel the extra weight didn’t adversely affect the plane and the extra flight time makes the idea of an electric Kadet much more logical as opposed to smaller batteries with an equivalent or higher cost. The ESC could have been easier to program and took a moment to figure out how to program it with the card. Overall I was pleased with the setup, but couldn’t give an opinion as to the aerobatic potential

Let me know what you think!

patternD

baylordsmith

My Feedback: (20)

Excellent review on this conversion. I really liked the pics. Ihave this plane and will be converting it soon. Thanks-baylor

patterndreamer

My Feedback: (1)

Thanks for the compliment and I hope your conversion goes well.

PatternD

cawiddison

Thankyou, PatternDreamer

I bought an almost completed Kadet Sr several years ago and it's been gathering dust since then, but now I'm motivated to attempt a conversion. Congrats on your conversion, it sounds like it went quite smoothly.
Couple of questions :
Did you use APC props?
CSRC recommends an APC 17x10; did you feel that this would overload your power system?
I'll be intersested to see how it behaves when you start to "expand the envelope," what changes you try, or improvements you may make in the future.
colin

cawiddison

Me again.
What servos did you use?

patterndreamer

My Feedback: (1)

At the moment, I'm using a 13x10 APC, but I'm considering moving to a 3-blade prop because I feel like I'm not loading the system up enough. Don't use a 17x10 unless you are sure about the ground clearance. The servos I'm using are DS821s. I had them laying around and figured they would work for this application. Hope that helps you out.

pilotgene

I modified the Senior Kadet into a low wing version, same tail & wing, just added landing gear hardwood in front of the spar, re-bent the supplied landing gear so the wheels set straight, added a plywood box, about 2"x2" fit blind nuts for either a OS .40 motor mount or box conversion into the firewall, made a cutout for fuel lines if I decied electric was not enough power, used a 2814-6 motor from BP hobby ($39) 60A ESC from them also, a 13x8 asp prop, and run 2-2200 ah
Li-Pos in parallel conection, a seperate flight pack for radio, takes off in 20' climbs great, lfies inverted almost hands off,
loops & rolls fine ( added ailerons), glides almost forever, very flat, lands in 20' at 10 mph.draws 45-50 amps, last 10 min+
Tried a 5000 mah Li-Po but it didn't hold up, connection came apart within the battery, 2 batteries in paralel work good.

bigtj10

My Feedback: (1)

Thanks very much for a great article on converting the Sig Senior to electric. It appears that you took most of the dihedral out of the wing? How much did you actually use? I built this plane back in 1984 or '85 and it was my first RC plane. I have been thinking about building a new wing with ailerons and very little dihedral but converting to electric first would be a kick. I guess I am a little late getting converted to electrics but I surely do appreciate the work you have already done and it is obvious that you are light years ahead of me in understanding electric power as it pertains to powering model airplanes. The photos are worth a million words!

Tom

JayBFlyer

My Feedback: (5)

Questions:

1) PatterenDreamer, do you have the spec's for the CSRC E46-4? CSRC no longer seem to have data on their website and only a little info on the box. I picked up one at my LHS as you seem to be having fun with it.

2) PilotGene, are you running 3s, 4s, 5s, 6s?

3) What are the flying weights of your respective models? Mine is coming in at 8 lbs. This is the ARF version. I think it was 6lb 11oz with only servos(no tank, battery, receiver, motor or engine).

4) Did you guys have to add additional nose weight. I mounted an Extreme Flight Torque 2814T/820 with 3 2200 3cell Zippies behind the firewall and still needed an addition 7oz to balance at the kit versions specified balance point which is at the leading edge of the spar. Where did you guys balance at?

5) If you guys can, please post a picture of your battery mount?

Thanks a bunch. I hope these birds are still in the air and flying well.

Jay

Thanks