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Jan 17, 2013, 03:18 PM
ripacheco's Avatar
Thread OP
Build Log

Back into RC with Electric SIG Kadet Senior

Update 2/26/13

Powered Trainer Setup
To finally learn to fly a powered model with the objective of being able to fly scale models.
My Other Planes

Original Post:

After over 20 years I'm ready to get back into RC. In the old days I flew a few gliders and was starting to learn to fly a glow-powered trainer. Then life got on the way.

Its been agonizing to figure out what I need to get re-started. So much has changed. Yet this is what has been decided so far:

1.- Airplane: Sig Kadet Senior ARF. (81 in wing span, 7 lbs -- 112 Oz. Designed for 40 glow engine or 500 Watt 1000kv electric motor)
2.- Motor: Scorpion SII-3026-710 turning an APC 12x6-E (per web site: produces about 90oz of trust which is 80% of the model weight... should be ok right?)
3.- Radio: Futaba 8FG Super. Maybe an overkill but i'm not planing on buying another radio for a long time. The 6EX maybe more reasonable but no room to grow?

Batteries, receiver, still to be determined

Any opinions, suggestions, rants and "are you nuts? comments" will be appreciated!

Last edited by ripacheco; Jun 24, 2013 at 11:45 AM.
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Jan 17, 2013, 03:33 PM
Retired US Navy
Evan D's Avatar
Opinions? Too litle motor and your choice of brand is expensive compared to the Chinese imports. Weight is not a issue. get a bigger motor in the 400-600kV range running on 4-6S depending on kV and prop. You can easily carry a 4000 to 5000mA LiPo and get 30-40 minutes of flying.
Jan 17, 2013, 05:18 PM
Registered User
Ed Couch's Avatar
For what its worth I agree with Evan on this. Presently I am flying the same with a HK G60 on 5/4000 lite polly pack with a 70 amp esc again a basic HK unit. Cost is minimal and the package handles the vehicle without issues. It would fly fine on a G46 if needed but you would have to add weight to nose. Add motor as cost is only a couple bucks more. You have a beautiful flying aircraft. I fly just about anything electric from 1/2 ounce to 53 pounds on electric and would not change. Leave the bird as a trike gear and just have fun. As far as radio, I have flown Spektrums since 2.4 started without any issues. I love the 7 channel unit but the new 6I has come a long way since it was brought out last year. They are inexpensive and receivers are as low as five dollars for aftermarket park flyer units. These I buy a half dozen at a time and use them on about all my small vehicles and quads. My airships also use the Hobby King orange units and have never had a failure with them yet. ed
Jan 17, 2013, 05:50 PM
Registered User
robert - welcome back to the hobby & I commend your choice of the Sig Kadet Senior - as I made the same choice a while back as a relatively new flyer but an old retired guy. The Sig Sr is a great EP aircraft & I really think you will be fine with the motor your have in mind as long as you want more leisurely flying & not unlimited verticals. I have a 46 sized motor with a 4 cell Lipo in mine, & that coupled with a 13X6.5 prop gives me all the power & speed I need. That big thick high-lift wing can only go so fast!

Might also mention that my club has used the Sig Sr for flight instruction (nitro powered) & have had a couple inflight failures of the wings due to excessive "g" forces in trying to recover from a dive. So the airframe probably isn't designed for heavy acrobatics but will handle the normal kind without any problem. Good luck with it.

Jan 17, 2013, 06:38 PM
Registered User
Welcome back to the fun. You will find that a lot has changed in the area of electric flight.
With the wide variety of electric power systems now, the sky is not the limit any more.

I would have to agree with the rest. A little more motor for less money.

If you really wanted to stay with a 40 sized power setup. I would suggest the following.


ESC, the 60 amp is out of stock.


Run a 12X6 to 13X8 prop and you will have a plane with enough power to get out of its own way. Should be close to a vertical take off. Yet it will fly for a long time at low power just putting around.

Now, if you wanted a little more motor then I would say this setup would be a good choice.


Same ESC


Run an APC 18X6 18X8 prop and you will have a lot of fun.

For a radio, I am an Airtronics person so I woulds suggest the RDS8000. If you watch the sales, it goes for $179.99

Jan 17, 2013, 08:19 PM
You sabotaged my plane.
eliworm's Avatar
Hi Robert,
I have the same radio and love it. Spend a little time playing with the settings you need and you will be able to find your way around and program it in no time.

As for the motor, there is no reason it won't work for a Kadet Senior. Sig shows 6 to 6.5 lbs for the plane. With the right prop and battery you will be fine.

Jan 17, 2013, 09:06 PM
Registered User
robert - another thing to consider with the radio is the Sig Sr ARF builds with separate servos for the ailerons, & this means you will need 5 channels with the ESC plugged into one on the RX. Then I also use a separate BEC on any fairly large EP plane, which is recommended to be plugged into a separate channel also. There you have 6 channels without any consideration of flaps or anything like that.

I made a choice to get the Hitec Aurora 9 radio right out of the box & almost everything I fly now uses 7 or 9 channels (I also connect a Guardian stabilizer that takes 1 or 2, & have flaps on a couple of A/C). So I agree with you that limiting yourself to only 6 channels won't give you any room to consider these other options as you move on in the hobby. Cheers,

Jan 17, 2013, 09:23 PM
Retired US Navy
Evan D's Avatar
The Futaba is fine. Keep it simple, KISS. You don't need a separate BEC but use a good ESC with an internal switching BEC. Use Y's on the ailerons too, KISS.
Jan 18, 2013, 01:53 AM
Registered User
scirocco's Avatar
With the 8FG (great radio BTW), the apparent initial simplicity of running a Y lead for 2 aileron servos is IMO well and truly outweighed just by the benefits of independent aileron subtrim, without considering redundancy and differential and spoilerons. It's much more straightforward to set up than Spektrum IMO as flaps don't get mixed up in there and is well covered in the manual. I'd argue that after model and trim memory and dual rates/expo, dual ailerons is one of the most worthwhile features on a computer radio and really worth exploiting rather than disabling.

Re power, I agree with the other posts that although the Scorpion can deliver the power you need, it is likely to be on the light side for balance compared with a .40 2 stroke, its muffler, mount and servo. And although the 12x6 can deliver the thrust you need, it's about the size you'd use for a high revving glow engine, whereas a substantially larger prop turning slower could deliver as much or more thrust for less power input. Anything over about 50-60% thrust:weight will be ample for the Senior, and if you're using around 14" prop, anything over about 450W input will do it, but you won't really compromise much with peak power even up around 600W.

I'll add a vote for the HobbyKing G60-400 on 6S as big as you need to balance, 14x7" prop and a Plush 60 ESC which has a solid internal switching BEC. It'll fly for ages at only 28A peak and probably around 10A average on 4000mAh+, and cheap packs will give many cycles at those loads.

Or if it turns out you need a lighter weight solution, consider the G32 - 530 on 5S with a 13 x 6.5
Jan 18, 2013, 09:00 AM
Retired US Navy
Evan D's Avatar
Scirocco, very good post. I agree that at some point taking the Y out is a good idea and he can even play with flaperons. Your G60 motor/ ESC/ battery/ prop suggestion is spot on though I'm trying not to sugest specifics as now is an excellent time to start learning what the numbers mean.
Turnigy has a relatively new ESC with a heat sink on it and an arming switch. Though I probably have 25-30 60A and 80A Plush in planes I like this new one and on planes that weight and space is no issue I'm putting these in their place. Planes like my big old timers.
Jan 18, 2013, 10:51 AM
Registered User
Ed Couch's Avatar

To me you don't need to split the ailerons a Y cable is simple and extremely reliable and this aircraft lands so dang slow flaps can get a beginner in trouble as the speed range can get very narrow between a full flap approach and stall when you are down to a slow walk with any wind at all. On the motor as stated I prefer the larger motors and not have to carry lead to balance. The G60 has proved to be an excellent motor and only around the 50 dollar mark. As Evan has stated the Plush ESC have always been reliable and without issue. Get the programming card as well. Really helps a lot. Hobbypartz motors and ESCs are exactly the same in most ways as the Turnigey line. Color shrinktubing and labeling are only difference. They use the same card for programming as well. Only problem is not always in stock but I'm tickled to see them doing well. I have no problems dealing with them either. Note on Hobbyking, buy you batteries from the USA warehouse first and only international as last resort. Hardware is never an issue but batteries can be held up. That is not the case in US warehouse as normal shipping is only five days or so. Hobbypartz shipping is free above a given amount and is also a week or less. My nickel. ed
Jan 18, 2013, 11:38 AM
Visitor from Reality
Hi Robert
For one, great choice of model! Few years back, BL (Before LiPo!), a clubmate of mine built one with a lot of Astro geared brushed motor in the front and 40-odd ounces of NiCad battery to feed it. The flying weight was never discussed, on account of none of us wanted to know, but in order to fit the 80" wing into his little Bee-Em sedan, there was, he told us, about a pound of brass tube and steel rod epoxied into the middle of his two part wing.

I test flew it for him. It took off, I watched it a while, then turned it. Flew it around, landed it. All at about the same level of minimal excitement. Later, with little ground school, we got his wife to fly it. She barely knew one end of those funny thing her hubby built from the other, but we had her circling the field and flying figure eights.

Sig make really great models.

Radio - your shooting for the 8 channel is good. I have the Futaba six, use it on tailless with elevons and ailerons on conventional models with two mixed servos. If you're into collecting dozens of models, its low model memory could get old fast though.

On aileron servos, go for two servos, tranny mixed channels. It is way better, I did it first that way back and won't have it any other way now. Motor - this is a lot of model, would have a look around to nail down a size of motor before spending out.

Big one - figure out battery access. You don't want a LiPo buried in there with the wing as the battery hatch. Trend with this big high winger looks to be a hatch between windscreen and firewall - again, go scrat around the Sports forum for Kadet conversions, there's plenty.

Undercarriage - electrics run to bigger props. My 60" span Four Star 40 electrocution flew best on a 15 x 10 and my Sig 1/5th Cub at 84.5" span used a 16 x 8. Both only had around 7000RPM at flat out. A taildragger conversion is well worth looking into to deal with a large prop, though it's much easier to deal with conversion on a kit vs a readymade.

A really bad place to avoid is sitting looking at a completed model while thinking 'Now, how do I get the battery in, and what do I do about the centre of gravity being four inches behind where it should be'. That's the polite version, BTW

Good luck with your project

Jan 18, 2013, 02:23 PM
ripacheco's Avatar
Thread OP

Progresss Report

Against my initial intentions I have started ordering things online. It had been my initial intention to support the local hobby shops but they don't stock what I want. Instead of letting them "order for me" I'll just do it myself.

So far...

1.- SIG Kadet Senior EG (red/white) has been ordered directly from SIG. (*1)
2.- Futaba 8FGA Super radio has been ordered from Tower Hobbies grr...(*2)
3.- No decision on motor yet Scorpions look nice... I wonder what the other fellows would say of a trainer equiped with a "competition" motor ...

(*1) They put a very nice guy on the phone who spent almost 30 mins explaining and re-explaining me about why they suggest a HIMAX HC3528-1000 motor for the Electric version of this kit. After all that chat how can order the kid from anybody else...

(*2) Tower Hobbies they dropped SIG a while back. Hate this consolidation crap.
When I was a boy all we had was Futaba radios. Things have changed a lot in the past 15-20 years but I coudn't get myself to change brands. Sorry Airtronics/Spektrum fans. What can I say I've been brainwashed by Futaba in my teens. To late to change . Radios have always been an almost "religious" matter. (not as much as the Scorpion vs. AXI vs HK though...)
Jan 18, 2013, 02:47 PM
Visitor from Reality
When I was a boy all we had was Futaba radios. Things have changed a lot in the past 15-20 years but I coudn't get myself to change brands. Sorry Airtronics/Spektrum fans. What can I say I've been brainwashed by Futaba in my teens. To late to change . Radios have always been an almost "religious" matter. (not as much as the Scorpion vs. AXI vs HK though...)

Know how that goes! Apart from the first radio I built back in Scotland, and a happy diddle with Hitec, I've been running Futaba ever since. Won't go too deeply here, but I did mess with a cheap-O from guess-what-country for a while. That it didn't come with any instructions at all didn't help, neither did the none-English-speaking 'customer service' I suspect it didn't work anyway, but it would have been nice to figure out if it didn't. Not that I was worried, I wasn't putting it into a model I'd put effort into.

Motors? I've got an AXI 2820/10 that I've had since well before they became available in the US. For several years, I worked a couple of blocks from our club site and flew the durn thing every day the weather cooperated. It is still fine. My AXI 2826 is still working following the day my Spektrum radio decided my model needed to dive into the ground from around 70 feet.

At the other end of the scale, I've had a cheapy motor body tear out of its star mount after a prop catch on the grass...

'Buy cheap, buy twice' - old, but still good...

Jan 18, 2013, 03:40 PM
ripacheco's Avatar
Thread OP
The planes I mention from my younger years were all kit/scratch built. After putting so many man-hours on the project we would never think of using anything but well trusted radios and engines. In my day that meant Futaba and OS/Webra ... I got a K&B on a trainer and I was told I was nuts. Didn't have much trouble but again I never really got to fly that model more than a few times. We flew gliders on a slope. 30-40 min flights any day...

This kadet senior ARF is a brand new experience for me...

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