View Full Version : SIG Something Extra Conversion

09-06-2005, 05:41 PM
Has anyone converted this to electric? Flew well with an Enya 50 but want to go to brushless. I like the Axis and think a 28 series would work - but would a 41 series be too big? The plane is about 4 -5 lbs without an engine. Any hints?

Mike Parsons
09-06-2005, 05:46 PM
Here is one that was done by Frank with a Hacker. Includes a video at the very end of the page. http://www.rccraze.com/something.html

09-08-2005, 02:42 PM
I've got a 4120-14 in mine with a 4s Kokam 3200 pack. Haven't had it up yet, but at about 500-700W I think it's about perfect :D.

I considered a 28xx, but just couldn't get the amount of power I wanted from those. A 28xx would probably be fine if you built it light, with the motor in mind, but since you (like I) built it for gas, I think the extra power is a good thing.

09-08-2005, 04:50 PM
Thanks for your advice -- Hobby Lobby suggested a 41xx but the specs on the 28xx seem as if it should be adequate - but you are right - it was built for gas and there was little regard for weight --- a little more balsa or glue was not an issue. For performance I will look at the axi 41 series - I like those little engines. They seem to pack quite a bit of power for their size.

09-08-2005, 05:54 PM
but the specs on the 28xx seem as if it should be adequate

Adequate yes, insane, no, and I wanted insane.:cool:

01-30-2010, 05:07 PM
Has anyone converted a sig mayhem to electric?

03-07-2010, 12:37 AM
Hasn anyone successfull converted a u-can-do 46 to electric. Would appreciate the info.

03-26-2010, 02:53 PM
U CAN DO glow is 6lbs or so.125 to 135 watts per lbs will start to get the 3d thing going.I'd look for a 1000 watt motor,5s or 6s battery.Something in that neighborhood.Enjoy,

03-26-2010, 03:29 PM
thanks e nut. would you know how to go about cutting a removeable hatch to change batteries?

03-27-2010, 06:32 PM
Check this thread:http://www.rcgroups.com/forums/showthread.php?t=426089

I don't like the idea of taking off the wing.As for making a hatch,I would instale all equipment first.Then you can place the batteries where the plane will balance correctly.This will help to figure out where the hatch needs to be cut out.I did this when I converted a funky40 from Ca models.here is the htread with a picture of the hatch I built.I had to add extra formers but not a bid deal.It's not a bid deal just take your time and find the formers in the fuse.http://www.wattflyer.com/forums/showthread.php?t=41774&highlight=funky+40&page=2


03-27-2010, 09:14 PM
Adequate yes, insane, no, and I wanted insane.:cool:

Check out the Hacker A40-10L motor. Mine will turn an APC-E 14X8.5 prop at 8450 RPM on a 6S2P A123 pack. Motor power levels runs at about 850 watts with this setup. Flight times with the 6S2P A123 pack is about 6 1/2 minutes, using about 60% of the battery capacity. This flys a 121 ounce Hanger 9 P51D Mustang Sport 40 ARF with authority.

It is NOT a good idea to fly those A123 batteries til they quit. Because they quit like a glow engine running out of fuel. I've had a full speed pass East to West on our field, turned around, and had to land dead stick, with a discharged A123 battery.

Last year, this same motor was used with a APC-E 14X10 pulling over 1000 watts, using the same A123 battery pack. The model that this motor was installed in flew for most of a flying season until the right wing aileron completely pulled out of the wing during a flight, hinges and all. (Due to lousy design of the glue surface of the hinges in the wing) The model and power systems pretty much survived that, but I'll never fly that :censor: model again. It was not fun to fly. That model hit 113 MPH during flight tests.

04-30-2016, 05:10 AM
Coming along pretty well. Finally decided on a covering scheme with the red and black Microlite I have left over from previous jobs. Mostly stolen from an Sbach. Stick built the tailplane for increased surfaces, cheaters and 45 degree rudder throws. Hopefully this will help me to avoid leading the nose. Was planning for 4s but may have to crank this up a bit. Extremeflight 55" Yak landing gear will accommodate up to 16" props. Planning for a docile 750-800 watts and estimating the upper end of 4 pounds. Tunigy Aerodrive 4240 620kv on the bench but may grab a motrolfly 3615 750kv if balance point requires. Not a bad kit but some of the balsa s extremely heavy.

05-01-2016, 01:59 PM
Simple front doweled (bamboo skewer) and rear magnet hatches. 3/8" neodymium magnets and these hatches aren't going anywhere. Front hatch needs to be opened through inside the main hatch access. Front hatch is just a carved/sanded block of balsa. Final sanding and covering on fuse, cut and fit canopy and this baby is at ARF assembly status.


05-01-2016, 08:33 PM
Success with NO LEAD!!!!
Dry weight comes to 3.75 pounds (minus a few grams of covering and tail hinges)
This puts AUW at a hair under 5 pounds with 4s 5000mAh pack.

Balance comes out with a couple inches either way of battery placement with a 7oz motor on 1.5 inches of 8x32 standoffs (to drawn prop location), 2.2oz esc and 1.5 ounce servos driving the tail surfaces. HS85's driving the ailerons. Blue/yellow Sullivan flex tail rods.

I will post PDF's of the stick built tailplanes after I pull them off of my other PC.....



05-04-2016, 12:28 AM
That's a wrap. Tunigy Aerodrive 4240 620kv does provide over 1-1 thrust on 4s and 14x7apc from a storage charged pack but I would like to have to hold it back more. Will be installing a 15x6 Xoar when the larger spinner arrives. We'll see how she flies.....

Here are a couple of plans I drafted for the tail feathers. There is a piece of 1/8" carbon fiber tubing just forward of the elevator hinge line, routered against a fence with a dremel bit in a drill press. All built from 1/4" x whatever is drawn stock with 1/16"x1/4" diagonal braces. Disregard the center line on the horizontal set. Set adobe to tile 100% with cut lines and they will print to scale.



05-11-2016, 07:17 PM
Looks good. I plan to finally get mine in the air this year.

05-11-2016, 10:47 PM
Thanks. Actually have some 5s packs being delivered any day now. I feel the 15" prop is a little excessive and can't get the thrust I want with the 4 cells and 620kv....

05-22-2016, 11:06 PM
Ok. So the plane flies great in all aspects. VERY floaty (of course, check out that wing area). Turnigy (whatever I listed above) gives a great deal of vertical authority on 5s with a 14x7apc.

Unfortunately, some Jackwagon (myself) decided, after flying fast planes all morning, to go into a full throttle 45 degree dive. Plane sounded like a kamikaze. It was great. Then the leading edge of the Hstab along with the center Hstab block decided to break at terminal velocity. It made an awesome 3' diameter loop which bled down a great deal of the airspeed. The Hstab decided to settle in with the right side leading edge about 1/2" below where it used to be. Managed to limp it in to a nice landing.

In short, I highly suggest beefing up the leading edge (If you use the PDF plans I posted above). The carbon fiber spar saved my bacon and also HIGHLY suggest adding fillet blocks to the above stick built Hstab at least underneath to better secure it to the fuse.

An hour fix and she will be fine. No more kamikaze dives however...

06-01-2016, 06:10 PM
Glad yours isn't too damaged.

I'm happy to say my maiden went much smoother. Flies pretty perfect, almost no trim needed. Though I think I'll have to try a 13x10 to see if I have a bit more speed and throttle headroom.

Also need to practice landing, I'm still a bit rusty there. Landing was smooth, but it took be the whole runway.

06-01-2016, 10:54 PM
She's all fixed up and performs well. Actually found the servo was a bit dodgy. I'm actually thinking that was the culprit. It would move ok but at certain points it would wiggle. Full travel was fine but moving it slowly or just a little caused it to hunt.
The plane came in for a nice soft landing after the incident so it didn't really get slammed. This is probably due to me using salvaged parts from a crashed plane.

This plane floats extremely well and moving the CG back a bit from the designed location should not be a problem. This will slow the landing down a bit. Good Luck!

06-02-2016, 01:07 AM
[QUOTE=birdDog;995844]She's all fixed up and performs well. Actually found the servo was a bit dodgy. I'm actually thinking that was the culprit. It would move ok but at certain points it would wiggle. Full travel was fine but moving it slowly or just a little caused it to hunt.

That sounds like the feed pack potentiometer in your servo has problems. IMHO, toss it in the round container, and replace it.

Even if it gets better with a lot of cycling back and forth, I'd not trust it. (Just replaced a Hitec 645MG servo last year for this reason)

06-02-2016, 01:54 AM
This plane floats extremely well and moving the CG back a bit from the designed location should not be a problem. This will slow the landing down a bit. Good Luck!

Oh, the airplane wasn't the problem with the landing, it's just I'm rusty. I haven't flown much in a long time so I'm out of practice nailing landings right where I want them.

Glad to hear all's well with yours, I'm replacing all my servos too. Mine seem to work accurately, but they're old and one of them is now way slower than the others so I don't really trust them.

07-24-2016, 04:12 PM
Well, I mashed my Extra last week, so I ordered a new fuse from sig (the wings survived pretty well. I've been looking at things I should do differently this time since I'm building it specifically for electric.

I was thinking first I should move the firewall forward. That would give me a little more room for battery placement, with my (now former) SE I had to have the battery right up against the firewall to get it to barely balance correctly. Alternatively I could use a spacer and mount the ESC behind that.

I also saw some people make the rudder/elevator bigger, and some stick build them. I was trying to decide if either of those were worth trying.