That still seems like a LOT of weight- are you absolutely, 100% sure that you're balancing at the correct point??

Is there any way you can put a spacer between the firewall and the engine mount to push the engine forward a bit? You could also try a heavy hub/spinner to put some extra weight as far forward as possible.

Your plane looks great, by the way. I just finished an SSE with as an electric conversion. With a 5S 4000 mah battery, up front, I am actually a touch nose heavy (about 1/8" - 3/16" ahead of the ideal CG).

Al

I agree it is a lot and yes I am sure it is correct. Manual says 3.5" from LE which is where is set the balancer at. I even rechecked it and then took out a tape measure to make sure the numbers on the balancer were accurate.

No offense! I've seen sillier things happen

Now go buy that Saito 82, lol

Thank you Al. I like what you did to yours too. What you did to the decking is something I thought about doing only I thought about it too late since it was already put together. The suggestions you made are the same as some of the club members suggested too so I bought the heavy brass hub. I'm also going to make a 1/2" thick ply block to push it out. They also suggested using a bigger engine so I think what I'm going to try is use blind nuts on the back of the 1/2 block which will be epoxied to the front of the firewall. I also bought an adjustable engine mount so I'll be able to try the .45 1st and if necessary make the mount wider for the larger engine.

Haha. Only thing I can think of is the modification I did to the rudder and elevator is throwing it way off. I just learned about 1oz in back = 4 oz in front, so I can't take much I'm sure. Would love a Saito but unfortunately pocket book won't allow for it. :-)

One of the club members just suggested because I modified the tail I should move the CG back to 4" so I did and put 2oz of led on top of the engine. What do you think?

btw I don't know how the picture looks to everyone else but the thumbnail is like the plane is on its' side which is not how I took the pic and when I click on the thumbnail it looks stretched and horizontal like it should be. Weird.

Nice work.

Zor

Hi there

I had a Somethin Extra I built in 2003, and it did come out tail heavy (those tail braces are important, don't take em off. It may be possible to replace them with Carbon however to lighten things up a little). My original designs were around a .46 Super Tigre 2 stroke, but after the first couple of flights we (my bro and an RCer friend) determined it just did not have enough oomph to be a lot of fun.

So I modified and beefed up the firewall to accept my .60 2 stroke Heli Super Tigre (amazing engine for airplanes, was originally used for a pusher design as you could swap direction of the crankshaft without having to use a pusher prop).
That did the trick of emptying the nose of dead weight, and really brought the SSE out of its shell. Had unlimited vertical, and still had the gentle characteristics the design is known for.

I believe, and I am sure others would agree, that replacing dead weight with engine displacement is a lot more useful and you can always throttle back. Needless to say, going with a bigger engine needs proper throttle management as with any thick airfoil fun fly plane. I have seen too many airplanes, even on the upper end of the recommended engine range, be underpowered.
I will never forget the EZ T38 Talon my brother had when I was a kid. One of our mentors said that a Fox .25 would be sufficient for the airframe (lowest engine recommended on the box), and on the first flight he took it up at full power and it kept on the edge of a stall at the same altitude until he turned it downwind and tip stalled. Lesson learned, after that I always put in an engine at least one displacement higher than on the box.
Eg. Funtana 40 + Saito 100 = Explosive beans in a can with cool bananas.

Sadly, the Extra met its demise after many flights by stupid pilot syndrome and performed an unintended stall into the ground following too tight a pull up from a loop (note to self, don't show off in front of family members. Got it?).
Amazing airplane, I hope to one day add a replacement to my fleet (in fact it would be my goal to buy just about every Sig kit, they rock!).

Good luck on however you proceed.

Dave

Moving the CG back sounds like a recipe for disaster

Yeah, I would not move it further back from the recommended range. Unless of course you like extremely squirely controls and a nose in the sky attitude :-)

Dave have you seen Sig is taking pre orders for a Sig Somethin' Extra ARF for $200.

Yeah, I remember seeing something about a SE Arf at one of the shows that was covered on RCU.
I, however, am one of the dying breeds who get as much pleasure building as I do flying. Plus I enjoy bashing and my own custom colour schemes.
Thanks for letting us know about that option though.

Any updates on the C/G decision?

I concur, I quite like the black canopy too.
Your's is also fine looking AL, I imagine it will make a fun electric. Did you lighten it up, or build it stock?

What I am trying now is making a1/4" thick firewall to epoxy in the existing one so I can install a .65 K&B sportster and see how that works out to keep the 3.5" CG. I have that brass heavy hub that I put on the .65 shaft because the mockup I did was showing me that even with a .65 it's still going to be tail heavy. The issue I have now is the brass hub is not moving. Don't know why. It is the same shaft as the .45 and it comes on and off the .45 without any issues. By not moving I mean I got it on but it is not coming off. I tried to unscrew it and the shaft ended up unscrewing from the engine instead. I wrapped a towel around the exposed shaft to protect the threads and put a clamp on it as tight as I could without ruining the threads and it still didn't come off. So my only choice is to work with it only it didn't screw all the way down so I put the stock washer and nut on it too.

Please tell me that the shaft thread is on opposite direction of the prop rotation. I don't want to try this if there is any chance of the shaft unscrewing from the engine whether that be on the ground or on the air.

Regarding the canopy color, may I suggest that you use the Rit Dye trick. I forget if I did it on my old SE or not. Some plastic that's used for canopies will take the dye while others either won't take it, or will take it with 'splotchy' results. The ones that I used it on had a nice effect.

Bob

On the canopy I used Lustrekote so I know it's fuel resistant. Took a long while but finally got it to where I'm happy with the results.

Sideoftheroad, I looked back at your build pictures and from what I can see the counterbalances were not the only mods to the tail surfaces, but in fact it looks like the elevators and rudder were enlarged compared with the stock kit. I may be in error if this is an update that Sig did since earlier builds?
If so, that would explain the tail heavy situation.

Dave, you are correct. Added counterbalance on the rudder and elevator as well as added length to the surface area. Somewhere 1/2-1" if I recall.

Yeah, that explains the extra weight. I never recalled the stock elevator having insufficient responsiveness (the rudder maybe), is there a reason why this was increased?
I would hazard a guess to make it more 3D like ...

Be careful with the larger elevator (esp at higher speeds for flutter, as I am sure you know, though the counter-balances may aide with that if they are weighted correctly), as I mentioned in an earlier post I pulled in too much elevator out of a loop and tip stalled, the ground spanking me for my insolence!
Some aircraft behave quite nicely when suddenly cranking in lots of elevator, giving a nice wall-like effect. Not this one (worst behaviour I have experienced was on a Great Planes Giles, that thing was tip stall nirvana. But it still lives, miraculously). This was (the SSE anyway) with the wings balanced and recommended C/G range.
Other than that, the SSE was very nicely behaved.
Enjoy!

Thanks Dave. It is pretty much stock. Unfortunately, with the battery, it comes in a touch heavy at 5.7 lbs. (the battery is a pound by itself though). I documented the build on my blog: http://alsrcsite.com/category/building-projects/sse/ (something I do just for fun).

I've run it up (on the ground) with a 12x6 prop and it's pulling over 700 watts, so I should have plenty of power on tap. I want to play around with a few other prop configurations before maiden though.

Nice Al; I enjoy perusing through builds and such, so I will take a look. Thanks!

Do any of you guys have experience with a "porky" SSE? At 5.7 lbs, I calculate a wing cube loading of 10.4, which is in the range for a sport plane, but a bit high for an aerobatic plane. I was hoping she would come in at about 5.25 lbs, but it was not to be ...

You'll only really notice it if you go fly a "light" SSE afterwards I imagine she'll still fly just fine

Most of my builds come out heavy because I over-engineer. I don't remember the weight of my SSE, but I am certain it was quite a bit heavier than stock with the 60 engine I had on it, plus some of the mods I made.
It will fly great, the only difference may be a stall at a slightly faster airspeed. I find slightly heavier airplanes just fly better. My Astro hog gained weight over the years and when it came to landing got better as it stuck to the ground. Wind penetration and buffet effect seem slightly better too. The exception was my aforementioned Giles which came out very light, and I did not like the way it flew.
I don't enjoy 3D (been there, done that), but prefer more smooth, precision like routines. I come from the older school of kit building, by which kits came out pretty heavy compared with todays standards. YMMV