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Old Jun 08, 2012, 02:36 PM
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beerbrewer's Avatar
Waverly, Nebr.
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Sig Kadet LT-40 not a Senior Conversion

Hello all, I am wanting to convert my wonderful Sig Kadet Senior (as per Sig Mfg it is actually an Lt-40) from a slimer to electric. I have done a bit of research and I am leaning towards E-flite Power 46 670Kv with a 60 amp switched esc. I would like to get 15-20 minutes flight time so I am thinking of using 6000 mAh batteries. This does mean I will need a different charger that can handle 4-5s Lipo's since my little one can only take 2-3s max.

I have not weighed the plane yet, but if I remember correctly what Sig's website said, it weighs around 7.5 lbs as a slimer.

I want to do this conversion since it is one of the most forgiving trainers around and my favorite one to fly, I just don't want to get slimed anymore.

Any feedback is welcome whether it be good or bad.

On October 22, 2012 Sig informed me that the LT-40 is the only Kadet with a 70 inch WS. So that is what I have, not a Senior.
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Old Jun 08, 2012, 02:48 PM
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Western Mass
Joined Feb 2008
407 Posts
That sounds like a good plan for a power system for the Kadet Sr. I have 7 pound P-51 that I convered to electric and am using a Monster Power (eflite clone) 46 motor with a 60 amp ESC and a 4 cell 4000mah battery pack. Granted, it's a much different plane, but I'm guessing if that power system is enough to power the P-51, yours will be plenty for the Kadet Senior.

One thing I would suggest on a larger electric model like this is to use a separate rx battery pack rather than running it off the lipo.

Incidentally, I learned on a Kadet and am currently in the process of building a Sig King Kobra that I'm converting to electric. I love the classic Sig planes.
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Old Jun 08, 2012, 03:32 PM
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beerbrewer's Avatar
Waverly, Nebr.
Joined Apr 2009
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Thank you for the reply. I was planning to have a separate 2s battery for the rx. I am not sure what size I will need to power the servos.

I can also say that I have a King Cobra. It was given to me by a friend who's daughter had found at a garage sale. It is partially assembled and I can tell that they were not up to speed in building a "craftsman" type bird. I haven't looked at it in a while but I know it will fly someday.
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Old Jun 09, 2012, 07:52 AM
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United States, LA, Angie
Joined Apr 2009
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A friend of mine just changed his Kadet over to electric. He put a 5065/410kv(60) in it with a 6S / 4200 lipo. It worked out well. I have that same motor in my P-51 and my Pawnee. Picked it up from heads up rc ZEE
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Old Jun 09, 2012, 08:55 AM
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Australia, ACT, Kambah
Joined Feb 2001
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Quote:
Originally Posted by beerbrewer View Post
Hello all, I am wanting to convert my wonderful Sig Kadet Senior from a slimmer to electric. I have done a bit of research and I am leaning towards E-flite Power 46 670Kv with a 60 amp switched esc. I would like to get 15-20 minutes flight time so I am thinking of using 6000 mAh batteries. This does mean I will need a different charger that can handle 4-5s Lipo's since my little one can only take 2-3s max.

I have not weighed the plane yet, but if I remember correctly what Sig's website said, it weighs around 7.5 lbs as a slimmer.

I want to do this conversion since it is one of the most forgiving trainers around and my favorite one to fly, I just don't want to get slimmed anymore.

Any feedback is welcome whether it be good or bad.
80", 6-6.5 lbs if its the ARF? Say 7.5 lbs with big battery packs

If you're looking for duration, 500-700W in should be adequate, especially with that big big wing. The Power 46 on 4S will only need about 480W for a 12x8 prop. If you can fit a 13x8, at 580W in you'll have a bit bigger margin for takeoff and climb, and enough pitch for stooging around at reduced rpm.

There's no point in talking about power systems without talking prop size first. If a 13" or bigger won't fit and you're not happy with 480W from a 12"x8 or 540W from 12x10, or 530W from 3 blade 12x7, then you need a cell count x motor Kv combination that is more than 4S x 670, eg 6S x 500, 12x8 ~ 760W, or 5S x 670, 11x7 ~760W.

Re charger - you could do a 4S pack as 2 2S packs in series, but it would be painful. If you want to charge 6000mAh packs, you're really going to want to upgrade to a charger that can deliver at least 100W, which would give you a 1C charge on 4S, better still a 200W charger for 2C like this: http://www.hobbyking.com/hobbyking/s...dProduct=12105. You'll also need a 250W power supply that can feed it.
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Old Jun 12, 2012, 12:48 PM
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beerbrewer's Avatar
Waverly, Nebr.
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Thank you everyone that has replied.

The plane is a kit plane not an ARF so it is going to weigh a bit more, possibly 8.5 lbs with large batteries, only one way to find out.

I have to measure for the max prop diameter that I can use, an 11 inch on the glow engine gave good clearance if I remember correctly. E-flite states I can spin a 14 x 10 with the Power 46 but need to measure for correct fit. A 5s battery may be the battery need if I have to go with a 12 inch prop. Max watts for the 46 is 925 and Sig states I need a minimum of 500 watts, (ARF???) so I think I am in the ball park. Worse comes to worse, a Power 60 with an 80 amp ESC.

My little E-flite charger is great for my 2s and 3s 360 mAh Lipos that I use on my indoor foamies, 2s for E-flite Park 250 and 3s for Turnigy Blue Wonder. I need to do a bit more reading under the batteries and charger sections since I don't want to buy a third charger due to ignorance on my part.

I am going to use the original rx and am not sure if it will handle a 7.2 VDC input from a 2s Lipo. May have to get an original Ni-mh that is closer to 5 VDC.

Getting that big beautiful wing back in the air is going to be awesome!
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Old Jun 12, 2012, 05:45 PM
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Australia, ACT, Kambah
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Quote:
Originally Posted by beerbrewer View Post
Thank you everyone that has replied.

The plane is a kit plane not an ARF so it is going to weigh a bit more, possibly 8.5 lbs with large batteries, only one way to find out.

I have to measure for the max prop diameter that I can use, an 11 inch on the glow engine gave good clearance if I remember correctly. E-flite states I can spin a 14 x 10 with the Power 46 but need to measure for correct fit. A 5s battery may be the battery need if I have to go with a 12 inch prop. Max watts for the 46 is 925 and Sig states I need a minimum of 500 watts, (ARF???) so I think I am in the ball park. Worse comes to worse, a Power 60 with an 80 amp ESC.

My little E-flite charger is great for my 2s and 3s 360 mAh Lipos that I use on my indoor foamies, 2s for E-flite Park 250 and 3s for Turnigy Blue Wonder. I need to do a bit more reading under the batteries and charger sections since I don't want to buy a third charger due to ignorance on my part.

I am going to use the original rx and am not sure if it will handle a 7.2 VDC input from a 2s Lipo. May have to get an original Ni-mh that is closer to 5 VDC.

Getting that big beautiful wing back in the air is going to be awesome!
Going to a Power 60 won't help if you're limited by prop size - it will actually make things worse as its Kv is even lower than the Power 46. For a 12x8 prop, even 6S on a Power 60 is less rpm than 4S on a Power 46

A Power 60 is not more "powerful" than a Power 46 UNLESS you are able to use the right combination of cells and prop size - the motor just can't be treated in isolation but must be considered as just part of a power system.

If you are using a 60A ESC with switching BEC, like this: http://www.e-fliterc.com/Products/De...rodID=EFLA1060, you don't have to use an Rx pack. If you do want to use a separate LiPo rx pack, 2S voltage is too high for most servos. But a small external switching voltage regulator like this is cheap and simple: http://www.arrowindhobby.com/hobby/e...ccessories.asp. This particular one just plugs into a 2S LiPo (or LiFePo) with a JST connector like this pack: http://www.hobbyking.com/hobbyking/s...arehouse_.html
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Old Jun 14, 2012, 01:33 PM
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beerbrewer's Avatar
Waverly, Nebr.
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Thank you Scirocco.

The esc that you suggested is the one that I am planning to use so it should be OK. I was thinking that a separate battery for the servos would give me a bit of safety factor if my main battery runs low.

I measured the clearence and a 14 inch prop might fit, a 13 inch will work just fine though. A couple of options is to simply put a little larger wheel on the front and mount the motor as high as I can. That should give me enough room to spin a 14 incher if a 13 inch does not give me what I want.

I am just getting a shopping list together and don't want to cheap out. That I why am going with E-flite for my Kadet.
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Old Jun 14, 2012, 02:03 PM
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If you are serious about getting maximum flight duration on a single charge, consider upgrading to a more efficient motor. Hyperion motors, available at www.allerc.com plus other outlets are excellent motors that are slightly lighter and more efficient than the e-flight. Also, they have a range of KV values in a given size so that you can optimize the motor and battery against the prop diameter constraints that you have on the Kadet. I have had good results from this brand.

Good luck,

Bob
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Old Jun 14, 2012, 02:18 PM
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West Saint Paul, MN
Joined Aug 2002
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I have the exact set up on my conversion that you listed in your first post. Power 46 with an old CC speed control I had sitting around powered by a 6000mAH TP prolite. I would have to look when I get home but I think I have an APC 13x8e on it. This combo seems to work out perfect.

On semi calm days and with throttle management this thing flys longer than I want to stand out on the flight line for "Multiple" flights so your wanting to get 15-20 minutes out of this set up can be achived easily as long as you are easy on the throttle.

I also did not weigh it but can if you want raw numbers but I never bothered because this thing lands and flys so slow it really doesnt matter to me. I could likely add another 5-7 pounds on this airplane and it would still fly just fine.

Harry
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Old Jun 14, 2012, 08:23 PM
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Australia, ACT, Kambah
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Quote:
Originally Posted by beerbrewer View Post
Thank you Scirocco.

The esc that you suggested is the one that I am planning to use so it should be OK. I was thinking that a separate battery for the servos would give me a bit of safety factor if my main battery runs low.
The main flight battery will still have many times the energy required for your rx and servos by the time it reaches the voltage where the low voltage cutout (LVC) on your ESC kicks in. LVC is there to protect your battery against over discharge, but it is not good practise if you want long battery life to rely on it as many ESC LVC voltages are lower than ideal for battery longevity. Instead you should time your flights and note the mAH recharged, and gradually build up flight time to the point where you are recharging a maximum of 80% of the battery capacity. In other words, on a 5000mAH battery, you don't want to use more than 4000mAH each flight. If you do this, and even on the odd occasion stray into LVC, you'll have more than enough battery for the Rx - your biggest problem if you get down to LVC will be managing the potential deadstick or inability to go around off a bad approach.

If you do decide to use an Rx battery, make sure you disconnect the red lead on the ESC servo connector - and remember most Rx and servos can't take unregulated 2S LiPo.
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Old Jun 15, 2012, 01:38 PM
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beerbrewer's Avatar
Waverly, Nebr.
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Thank you Bob and scirocco,

I have looked at the Hyperion in the past for foamies but I went with something less expensive. In this case it might be prudent to go with the best I can afford since I truly love my Kadet Senior. Lighter and more efficient is good, but will take a bit longer to afford.

The tip on monitoring battery consumption is welcome for sure. I have seen what you described before and am glad you reminded me of it. The last thing I want is to have a bunch of balsa kindling from an "operator head space error" on my part. I believe that I read the E-flite esc will go into a low power mode vs total cutoff if I reach LVC, I have not checked on the Hyperion's LVC modes.

Thanks again, Terry
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Old Jun 17, 2012, 04:05 PM
Visitor from Reality
United States, VA, Arlington
Joined Dec 1996
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HI Terry
There's a lot of info around on Sig kits - you might want to poke around the sports model section too. A lot of stuff on the Seniorita conversion may help you out too.

On the prop issue, the Senior's trike UC is designed around a smaller glow engine prop. Many Seniors and 'ritas have been converted to a taildragger set-up to get more prop clearance, stiffer UC and less weight too.

Wouldn't even bother over the ESC receiver supply issue - leave the receiver pack in there that did fine for glow power and disconnect the ESC's BEC supply. I did just that when I electrocuted a Sig 1/5th scale Piper Cub and it never noticed those four nimh cells somewhere in there.

Good luck with your project

Dereck
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Old Jun 19, 2012, 04:11 PM
Straight up is all I ask
Fairfield Ct USA
Joined Apr 2002
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I have a converted Kadet Senior with trike gear . Max prop is 14" I run a 500kv scorpion 4020 that does 1000 whatts on 6s with a 14x7 E
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Old Jun 26, 2012, 01:43 PM
wbuttry
sikeston mo
Joined Apr 2009
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The best motors i found are neu motors or scorpions. I got a tower trainer 40 with 61 inch ws and i got 2 3s 2200 20 c dischare run in paralell and a suppo 70 amp esc. And then im running a 20 amp esc not hooked up to anything except my reciver as my bec. And it flies fine i get 15 to 20 min flites. And that is taking off and circling around and practiceing landing. Probally get more on straight and level flite and it weights a whole lot less than the glow version ever could It is so smooth in turns and glides perfect and rides the heck out of thermals.
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