I started work on my Sig kit that I got after Christmas. Going to build it a little different from stock since I want a bit more out of it than the run of the mill trainer.

The first thing I am doing is balancing the wing for stability in rolls. I spent about 30 minutes with a gram scale, the kind used for weighing food stuff for diets. I start with the ribs, weigh each one and group them according to weight. They run between .003 and .007 kg each. The ribs that land on the Fuse don't really figure in on this, so I dont weigh them. Starting with W4, and working out to the tip I go heaviest to lightest, with the final rib being on that is .005 kg. Reason for this is the last rib takes a beating, and while you dont want a lot of weight at the tip, you want a sturdy one.

Next I weigh each spar, LE and TE piece, then divide them up to be equal L>R, and then weigh the ribs in with each wing set. Once done, I then take the muffler and add it to the mix by weighing the right wing with muffler, then subtracting the left wing from right wing and then go through the spars and swap the difference. Once done the planes lateral balance should be close to perfect when completed, roll rates should also be equal in performance. I know, most will poopoo this move, Why waste your time, blah blah blah, but hey it has to be balanced one way or the other, why not from the start. Besides, with my luck I would wind up with all the heavy ribs on the outboard right wing and have to add 6 ounces of pennies to the left wing, which would suck if I have the covering on.

The mods I have in mind are few, but good ones. The first, it will be a tail dragger. Second I will be putting a bolt on wing instead of rubber bands. Finally the dihedral will be very shallow, something like 3 degrees as opposed to the 6 degrees of the kit. Dropping the difference from 3 3/4" to somewhere around 1 1/2" to 2". For power an OS 52 Surpass will be in the nose. I think I have a 12x8 prop for it, but cant remember off the top of my head the exact props I picked up for it.

If I get truely ambitious I may go for dual servos on the wings, but SIG had changed the kit to use center torque links instead of the bellcranks and pushrods of earlier kits. No horns sticking out of the wings, nice clean lines, but cant do flaperons for the fun of it with one servo. Would be pretty cool to have it just hover in the air with the ailerons hanging down.

The left wing has been built, lower, upper spars front and reat and TE are in place. The wing structure is solid, the design uses laser cut shear webs between the spars and ribs, and fit perfectly. So far every piece fell tightly into place, no trimming or sanding of any part was needed. I built the wing on a 3/8 Foam panel that is the type used for making Foamies, very dense, and flat, and had that taped down to my glass topped artist table. The wing came out nise and true, but after I took it off th e board I discovered the lower spar has a very slight bend to it that is only noticeable when you lay it down on the glass top. there is a 1/32" gap at the root. I can most likely get that out with the covering. I still need to attach the leading edge and W1 rib, but I first need to make a new Dihedral gauge with the 3 degree offset instead of the included 6 degree one, and also make new spar joiners out of plywood.

For the bolt downs, I plan to use dowels, so for the leading edge I am looking to cut back about 3/8-1/2" and insert 1/4" plywood at a slight angle, with 2 pins, and on the Fuse another 1/4" piece behind the windscreen ply so that when I insert the wing, the pins will be pointing up at a slight angle to lock the wing in place. Since the rear of the wing is angled down I most likely will put the bolt block in at a matching angle so the bolt heads lay flush with the wing, and will incorporate plywood in place of the balsa that currently goes there.

So far I am fairly impressed with the Sig kit, it goes together much nicer than the Top Flite P-51 GE I have going.

Pics soon as I take some.

Are you going to add sheer webs all the way to the last rib? Aparently Sig doesn't think they are needed. I think they should be on the main spars at least.

Joe

I don't see a reason for them. The plywood wingtip adds a lot of strength and rigidity to the wing.

Ihave the wing nearly completed, just need to work on adding the torque tubes and ailerons, and its done. Well, done by the book, once Ihave the fuse assembled I will go back to the wing and do the pin blocks for the bolt down mod.

The Dihedral is 1 3/4". Should be easier to fly upside down, and have a bit more performance to it.

This has the wing sitting on top of the cabin right. I did this on a similar plane and had the dowel in the wing (single) protruded down out the bottom at a 30 degree angel tying it into the center ribs with ply on each side from main spar with notches for the rear of the leading edge, hard balsa top and bottom, shaped as filler with carbon tow securing it to the dihedral brace and leading edgef. The rear of the dowel was inserted into a hole in the joiner. It's been rock solid for a year now

I started on the Fuse last night. Have all the parts separated from the blanks, and the firewall assembled. The OS .52 fits nicely, but not sure how I am going to hook the throttle up.  I dont know if the carb can be rotated 180*, it is opposite of the location for the pushrod.  <div>
</div><div>One thing I found strange, they go to the trouble of laser cutting most of the fuse parts, but still die cut the long bottom and side pieces. The dies were a little soft in some places and it was tricky trying to separate the parts cleanly.  I guess their laser cutter has a short bed in it. </div>

I have all the parts together now, ready to glue, but first i need to cut some new parts for the mods. I am taking F7 and replacing it with 1/4" plywood. The shelf is down 1/4" from the top of the fuse, so its a perfect fit.  Once I have the wing aligned I will put in a couple 1/4-20 blind nuts and call it done.

The Landing gear placement though I am still struggling with. I think centered on the leading edge of the wing should work, but not 100% sure. Need to figure that out so I can put 1/4" ply backer for bolting the gear to.   Once I have that then I can glue it all together.

I am still going to glue the LG block as per plans and have the nose gear fitting on the firewall just in case I want to switch to conventional LG.

I just looked at mine which has the same tail dragger mod on it. The center of the landing gear is about 1" back from the leading edge of the wing. I also did the bolt on wing from the outset. This is such a great plane. I learned to fly on it, train others on it, and convert it to floats for our float flys. Always my reliable flyer.

Thanks, thats perfect, it puts the block behind F2, so I dont have to worry about stuffing it in under the tank floor.  Now to find the right landing gear for it.  I feel a lunch time trip to the LHS coming up. <div>
</div><div>BTW your avatar, is that a Connie or a B25? </div>

I used an aluminum strap landing gear, I think it was left over from a Sig Somethin' Extra kit. Works great.
My avitar is a shot I took out the escape hatch of a B25 we were flying in, over Utah Lake a few years back. Slow, loud, bumpy...man that was fun!

Envious^^<div>
</div><div>I only get to restore a B-17, never had the chance to actually fly in a Warbird yet. </div>

Were you involved in the B-17 restoration in Houston some years back?

No, just in the B-17E in my sig.  It's local to me, but the owner has been involved with a few restorations on other projects including Liberty Belle. He actually got to be in the left seat on the Belle.

Practice putting on your forelorn face and maybe they'll take pity on you and give you a ride My wife was the one pushing to fly in the B25 and it didn't take much arm twisting to get me on board. It was expensive, almost $800 for the both of us for under an hour flight. I've never wished that I hadn't spent that money. We were both grinning for the rest of the day. Now, if I could only snag a ride in a P51!

Well, hopefully within the next 5 years or so, the Rat will be flying and with my time spent on it, I get to be one of the crew.  Heck I might even get to fly the right seat.

Well, brief update on the build. Last night I took the assembled fuse and placed the new gear on it, and the tail gear.  I located the main gear axle centered on the leading edge and found the bolts straddle F2. I cut 2 1x3x1/4" plywood blocks and placed them on either side of F2, and they fit perfectly.  LG mounts done, now to glue it all together. <div>
</div><div>For the wing bolts I took F7 and cut a new piece out of 1/4" ply in the same shape. What I found interesting, the shelf for F7 is 1/4" deep, so the new piece fits flush with the top of the fuse.  I will need to check the wing fit with the ailerons and servo installed for clearance before I glue it in. </div><div>
</div><div>For the LE pins I took a 1x3x1/4" plywood block and placed it in front of F2 at the top, and sanded the edge to match the angle for the windscreen.  I should have plenty of meat there to pin to. On the wing, I am thinking of slotting behind the LE 1/4", making a piece from 1/4" ply to match the dihedral, and notching it to go around the ribs halfway up so they will all lock together as one. The piece will extend down about an inch or so depending on the fit, and will be slightly smaller then the width of the fuse inside so it will lock the wing in side to side with the pins holding the LE down. </div><div>
</div><div>For the tie down bolts, the TE blocks that has the torque tubes has a 1/16" plywood piece that goes on top from the kit, and I am thinking of shaving off 1/16" from those blocks and putting 1/8" ply on top instead for something more solid to bolt down to. </div><div>
</div><div>I picked out my colors too. The overall color will be white, the leading edge to the forward main spar on the wings will be metallic purple, and the control surfaces will be bright red.  With the kit decals and this color scheme it will look like the original, but different. </div>

Fuse got glued together last night. All that is left is glue the corner braces on the firewall, file down F7 to fit better, glue it in, and sand the whole thing.   <div>
</div><div>For the wing mount, now that I have the fuse together, I found that the wing sits inside the fuse, not on top as I previously though, so the pin block is going to be larger. I will glue two 1/4" ply pieces together, one piece to slip inside the wing, the other to fit below the wing. This piece will have the pins in it that will slip into the F2 and ply block I installed in front of it.  </div><div>
</div><div>The tail will be done tonight, then I will work on final assembly of the wing and get it all covered, hopefully it will be airworthy by the end of the month. </div>

Well, here are the pics of what has been done so far. ALl major components are assembled, the Fin and Stab just need theLE sanded to shape, the wing needs the fiberglass strip glued on and the ailerons fitted.

Once Ifinish up with those items, it is on to putting in the controls. Ithink Ihave the carb linkage figured out, Ispun the carb 180* to put the link inside of the mount, it was touching the mount and I had no way to get a linkage to it.

The tail wheel assembly that I have is going to take a little work to get it to fit and work correctly. The setup on the P-51 is to solder a brass tube to it, flatten the end, drill a hole and mount a ball and socket to it. Imay or may not have enough room to do that.

My scroll saw was in my barn, and Ihad to take it apart to clean it up, de-rust it, repaint it, and reassemble it. Well Iam at the repaint part, hope to have it reassembled tomorrow so Ican finish the wing bolt mod.

A few more days and it will be ready to fly! Yeah!

Wing pin block is done, just need to cut the extra dowel off, and epoxy it into the wing. Then I can square the wing to the Fuse and drill the bolt holes, tap the ply and be done with this mod.

Nice.  I built a Sig Kadet LT 40 back in 2001.  I just flew it for the first time last month.  I have now had it up twice, and I think I am ready to land on my next trip to the field.  It is really easy to fly and control.  It just seems to float.

.

The wing assembly is complete, the ailerons are fitted and trimmed, the fiberglass center strip is done, all that is left is to drill the mounting holes for the bolts. For that I took a 1/16" plywood strip that covers both of the balsa blocks the torque tubes are in completely, as opposed to the ones in the kit that only cover a small part. I used one whole piece instead of the two little ones. <div>
</div><div>The tail wheel is in, and works good. </div><div>
</div><div>The covering was started last night, the stab is done, and looks really good, tonight I hope to get the rest of the covering done.  Debating on whether to cover the fin in red, or white with a red rudder. The wing will be white from the main spar back, and metallic plum forward of the spar, with red, or blue ailerons. </div><div>
</div><div>It will be one colorful plane. </div><div>
</div><div>That reminds me, I need to put some filler in front of the plywood so its smooth under the covering. </div>

Excellent subject and modifications, acdii. I did mostly the same thing to a LT-25 a few years ago;

see: http://www.rcuniverse.com/forum/m_52...tm.htm#5214279
Adding some wheel pants would pop the whole project.............

I glued hardwood blocks in the bottom of the LT-40s I've built. I used nylon bolts for the landing gear. Using a servo for each torque rod isan easy mod. I've mounted them side by side in the wing center section.

The stock LT-40 will hover and torque roll with an OS 46FX.

Covering is almost done. The Stab, Fin, rudder and fuse are done.  All that is left is the Elevator, wing and ailerons.  Then fit the motor, radio, fuel and battery. <div>
</div><div>
</div><div>One thing I noticed that I will need to correct is one pin isnt long enough, when the wing is set in place, it site back about an 1/8th inch from F2, and I didnt have a way to look inside before I set the pin length, which I though was long enough, but isnt, so I will take them out and make them both 1/4" longer. </div><div>
</div><div>It looks pretty good in white with red feathers. </div>

Finished the covering tonight. Looks good. Tomorrow I fit the radio, mount the motor, drop in the tanks and prep it for it's maiden.  Pics when I get it assembled tomorrow.

She's all done(except Imissed 2 screws on the tail wheel, will get that later when Irun her up.)

Ichanged the title, sinces it is a .52 and not a 40 running it

Imounted the switch and charge jack where the black of the decal is so it doesnt stick out. Ialso put a fueling line on so I dont have to unplug the line from the carb to fuel it, the line sticks out at the front left, and has a plug. Eventually I will get a fule dot like I have on my Dewey. Ilossely zip tied the fuel lines to the carb throat to keep the vent off the hot engine parts. Since the muffler is pointing down, I wont need to worry about taking the line off when I fuel, I can stop the pump when I see fuel in the line and reverse it to suck some out. If Ido miss it and some overflows, it will run down to the ground and not into the motor.