40% Extra 300 Construction by-the-numbers
04-05-2006, 10:38 PM
#1
40% Extra 300 Construction by-the-numbers
Several have asked for this kind of "by the numbers" thread for building the Extra 300- to supplement the PAK instruction booklet.
After reading the instructions several times through, construction started.
With the front bulkhead on the 300 now full size one uses the edge of a table to get the engine compartment aligned while gluing. I used the wood glue for construction of the box. Several clamps in place.
Al, forgive me. While visiting my father two weekends ago, we did some engineering. Three engineers around the table talking about statics. My sister came down and gave us her input. We are all EE's but still remember our statics enough to give it a shot. The results are 1/4 lb off of the engine box sides. Holed drilled then a band saw to take out the triangles and center area of the box sides. This was carefully done. The model was tested somewhat in the prototype, which had equal amounts of material in the front- wing tube mount area as this new one.
The fuselage sides were assembled per instructions The 1x1x72 inch aluminum triangles were purchased at Lowe's. The fuselages were joined and doubler added. A scrap 3/8 inch piece was spaced for top and bottom of the fuselage joining point. The 3/8 squares glued on the tops and bottoms with mostly wood glue, skipping about an inch every 6 to 8 inches and putting thick CA at those spots. THis allowed construction without delay of waiting for the wood glue to set.
Finally the vertical stringers were glued in with 3/8 inch square pieces, and the rear doubler glued into place.
After reading the instructions several times through, construction started.
With the front bulkhead on the 300 now full size one uses the edge of a table to get the engine compartment aligned while gluing. I used the wood glue for construction of the box. Several clamps in place.
Al, forgive me. While visiting my father two weekends ago, we did some engineering. Three engineers around the table talking about statics. My sister came down and gave us her input. We are all EE's but still remember our statics enough to give it a shot. The results are 1/4 lb off of the engine box sides. Holed drilled then a band saw to take out the triangles and center area of the box sides. This was carefully done. The model was tested somewhat in the prototype, which had equal amounts of material in the front- wing tube mount area as this new one.
The fuselage sides were assembled per instructions The 1x1x72 inch aluminum triangles were purchased at Lowe's. The fuselages were joined and doubler added. A scrap 3/8 inch piece was spaced for top and bottom of the fuselage joining point. The 3/8 squares glued on the tops and bottoms with mostly wood glue, skipping about an inch every 6 to 8 inches and putting thick CA at those spots. THis allowed construction without delay of waiting for the wood glue to set.
Finally the vertical stringers were glued in with 3/8 inch square pieces, and the rear doubler glued into place.
04-08-2006, 09:19 PM
#3
RE: 40% Extra 300 Construction by-the-numbers
I drew a center line down the center of the worktable (an unfinished door). Used a SMART LEVEL to double check how close the fuselages were (tops parallell). Basically if you use the long aluminum straight edge or 78 inch corner aluminum stock this ensures the fuselage front and back piece are glued together straight. A hint. When you splice two pieces of balsa 3/8 stock together for the longerons, glue them with the splice opposite the glued surface. Basically this makes a stronger joint. The plywood sides will flex in and out, but not top to bottom. I had to put a shim under the back of one side since the door was about 1/8 inch off on one side as compared to the other. When the front box is glued in place straight, the back of the fuselagee (rear) will come together perfectly.
I put the triangle 78 inch stock in the corners and then clipped the fuselage sides to them in a few spots. Then carefully cut top and bottom pieces so they were the same size. Then glued in the bottom pieces (F3 F4 and f5) The balsa cross-pieces (cut the top piece first then cut the bottom one to match it). This insures the fuselage is square.
I put the triangle 78 inch stock in the corners and then clipped the fuselage sides to them in a few spots. Then carefully cut top and bottom pieces so they were the same size. Then glued in the bottom pieces (F3 F4 and f5) The balsa cross-pieces (cut the top piece first then cut the bottom one to match it). This insures the fuselage is square.
04-08-2006, 09:25 PM
#4
RE: 40% Extra 300 Construction by-the-numbers
As you can see above, before gluing in F3, F4 and F5 (the bottom bulkheads), first put the tailwheel plate in, and then a small piece of balsa at the rear of the fuselage. This rectangular piece was 1 1/2 inches wide. Taking in consideration two 3/8 squares pieces and the 1/8 inch fuselage sides, this put the rear of the fuselage at 2 1/2 inches per the plans.
There were a lot of triangles in the kit. Lay them out by size. They go in front and back of each of the forward three bulheads, and around the engine box. As you can see I took a hole saw and put a few lighening holes in the back area as well.
There were a lot of triangles in the kit. Lay them out by size. They go in front and back of each of the forward three bulheads, and around the engine box. As you can see I took a hole saw and put a few lighening holes in the back area as well.
04-08-2006, 09:28 PM
#5
RE: 40% Extra 300 Construction by-the-numbers
I put the wing and stab tubes in place and checked alignment. It was very close. The triangle stock has to be shaped when going in the corners around the engine box and the fuselage sides. I put wood glue in the corner and a few drops of CA on the edges of each triangle. The CA set quickly while allowing the white glue to dry.
04-08-2006, 09:36 PM
#6
RE: 40% Extra 300 Construction by-the-numbers
After I put the stringers in, then I put the diagonal- cross pieces in. They are staggered so the top and bottoms cross opposite. I went ahead and built a pipe tunnel out of light 3/32 balsa in case I go with long tuned pipes. Marco Benincasa did this at the Tuscon Shoot Out last year and I was really impressed with his power setup. I heard that the long pipes make the idle a bit tempermental, but since there are no tailslides at the Don Lowe Masters, this should be no problem. I had to remove the center of bottom bulhead to make room for the pipe tunnel. Will put the rudder servo tray up higher to clear the pipe tunnel.
04-10-2006, 11:42 PM
#7
RE: 40% Extra 300 Construction by-the-numbers
Some additional pictures of the pipe tunnel.
Canopy deck. Make sure you allow 1/8 inch overlap for the two 3/8 inch side stringers. I glued the bottom 3/8 inch side stringers on, placed the canopy on the airplane, then glued the front three bulkhead/formers in place. I used a clothespin to clamp to the front fuselage bulkhead. Next is to mount the ply mounting tabs (its easier to get to them before sheeting the top of the canopy deck).
Canopy deck. Make sure you allow 1/8 inch overlap for the two 3/8 inch side stringers. I glued the bottom 3/8 inch side stringers on, placed the canopy on the airplane, then glued the front three bulkhead/formers in place. I used a clothespin to clamp to the front fuselage bulkhead. Next is to mount the ply mounting tabs (its easier to get to them before sheeting the top of the canopy deck).
04-19-2006, 12:14 AM
#8
RE: 40% Extra 300 Construction by-the-numbers
Rough assemble the canopy deck. Glue in the formers. Now, what angle do you put the rear former? Align the rear former so it's parallel to the back deck. It does not have to be exact. Just close enough so you can glue in the stringers in place.
The sheeting was straight forward. Cut two pieces, glue them together with some thick CA. Immediately sand the joint with a sanding block, then flip it over and sand the other side. I cut about 1/2 inch off each at the rear, tapering up to the front. That way the side pieces glued in are at about the right angle to fit on the canopy deck. See pictures. I put a litle water on the underside of the sheeting and set it on top of the deck, with some books on each side, to help shape it generally to the frame.
The sheeting was straight forward. Cut two pieces, glue them together with some thick CA. Immediately sand the joint with a sanding block, then flip it over and sand the other side. I cut about 1/2 inch off each at the rear, tapering up to the front. That way the side pieces glued in are at about the right angle to fit on the canopy deck. See pictures. I put a litle water on the underside of the sheeting and set it on top of the deck, with some books on each side, to help shape it generally to the frame.
04-19-2006, 12:19 AM
#9
RE: 40% Extra 300 Construction by-the-numbers
The next step is to glue the sheeting to the deck, trim the edges, then position it. Before gluing on the sheeting, I will mount the tabs for the six 6x32 cap screws and mounts. Its easier to get to them before its sheeted. Finally once everything is positioned, one can glue on the back deck to get a clean interface with canopy deck.
BTW. I glued the 1/8 x 3/8 pieces to the underside of the rear deck pieces, added additional 1/16 pieces to fill the rest of the gap, only to find that I had to trim about 1/32 off the front and back for a flat mating surface (flat with the tops of the fuselage sides). A little sanding and it fit very well.
BTW. I glued the 1/8 x 3/8 pieces to the underside of the rear deck pieces, added additional 1/16 pieces to fill the rest of the gap, only to find that I had to trim about 1/32 off the front and back for a flat mating surface (flat with the tops of the fuselage sides). A little sanding and it fit very well.
04-22-2006, 07:37 PM
#10
RE: 40% Extra 300 Construction by-the-numbers
Canopy deck sticks are glued in, then the 6 tabs for the mounting blind nuts. A 3/8 spacer is glued in at each location. Finally sheeting is glued on. Make sure you sheet on a flat surface so the deck will not warp. I used wood glue for the stringers and then thick CA on the edges. After wetting the balsa on the outside, it provides for bending of the bala at the bottom part.
04-22-2006, 07:42 PM
#11
RE: 40% Extra 300 Construction by-the-numbers
For the rear deck, push it up against the canopy deck and draw a mark for the location. Remove the canopy deck and glue on the rear deck. I used wood glue on the inside and some CA on the outside edge. I started with one side, pushed down and aligned the side with the fuselage side. THen I put CA on the other outside edge (the deck will lift up a little on the other side to get the glue in. Then press that side down so its aligned with the fuselage side. Finally glue the front and rear ply formers in place and then put balsa sheeting across the front of hte deck.
04-22-2006, 10:52 PM
#12
RE: 40% Extra 300 Construction by-the-numbers
Gluing the rudder fin was easy. First step was to glue the vertical post, then the fin. Note the center line at the top of the fin. This enabled a straight mount with respect to the centerline. Sight down the line with a 1 meter ruler and it give a pretty good alignment. The balsa and foam pieces were cut perfectly and I only had to sand a little to take any gaps out. Finally do the fillet sheeting. Use some paper (folded around the fuselage curve) to make a paper template, cut out the balsa pieces and glue them in place with CA. I sanded an angle (from none to a very strong taper at the back part of the sheeting pieces. That way it fit flush against the fin sheeting sides. I used a couple of 3/8 inch cross pieces to secure the fin, and the second 1/8 ply piece gave the sheeting the correct spacing to glue to so its flush with the back deck. Some sanding with a block and some 80 grit and it looks great.
08-02-2006, 10:32 PM
#16
RE: 40% Extra 300 Construction by-the-numbers
Took a break from building and flew some pattern over the last couple months. I got the other one in the air for a few spins. I've put the new kit back on the workbench. Need to determine final engine and pipe configuration, complete mounting the elevators, surmise any other mods, take dihedral out, and then prepare for covering. Pictures courtesy of Xavior.
08-03-2006, 11:18 PM
#17
RE: 40% Extra 300 Construction by-the-numbers
I decided to take the dihedral out. Below pictures are self explanatory. The process took about 2 hours this evenng and its about ready to glue. I suppose that I'll pick up some expanding foam stuff to fill in the gap. The process started by shoving some wire on the bottom part of the tube/foam interface and working the tube so it came to the middle of the center root rib. Cut out a small portion of the center rib and then made a light ply piece for the center area to strengthen it.
08-04-2006, 06:55 PM
#19
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RE: 40% Extra 300 Construction by-the-numbers
why not cut a new root rib with the tube hole correctly located for the 0 dihedral??
wouldn't that be stronger than adding a lite ply plate?
tony
wouldn't that be stronger than adding a lite ply plate?
tony
08-05-2006, 10:52 PM
#20
RE: 40% Extra 300 Construction by-the-numbers
The lite ply plate doubler, plus adding the filler piece in should be approximately 2X as strong as just the root rib, plus the kit pieces are laser cut. I could not get another set of root ribs cut/drilled as accurately. This really is the straightest kit I've seen. I could not detect anything out of alignment, or even the slightest warp in the wings, stabs, or rudder. I'm almost afraid to do the finishing sanding on the wings and stab to mess up the perfect surfaces.
A disclaimer. I do not recommend these wing modifications from the standard kit under normal circumstances. I am testing to see if this will make a great flying airplane even better. The only place I expect to see a difference is in the 1 roll circle and rolling loop maneuvers.
Don
A disclaimer. I do not recommend these wing modifications from the standard kit under normal circumstances. I am testing to see if this will make a great flying airplane even better. The only place I expect to see a difference is in the 1 roll circle and rolling loop maneuvers.
Don
09-02-2006, 09:49 PM
#21
RE: 40% Extra 300 Construction by-the-numbers
Landing gear.
All items carefully weighed. Landing gear is 7 oz lighter. Small 3/4 inch aluminum stock was subsituted for the 1 1/2 inch stock. The carbon gear is 1/2 inch wider at the base and 2 inches more spread. Aluminum channel and small aluminum stock alternated.
Engine box dimensions for mounting a DA 150 are as follows: 9 3/4 inch front of the firewall to the first bulkhead on the left side, and 9 3/8 inch from the left side. The engine is offset approximately 2 inches to the left and the engine holes are 5/8 inch from the top of the engine box. Attached are some pictures that may be helpful.
Started to sand the fuselage. I hope to take approximately 1.5 oz off by sanding. The 1/8 inch sheeting will hopefully be sanded down to about 3/32 to 1/16.
All items carefully weighed. Landing gear is 7 oz lighter. Small 3/4 inch aluminum stock was subsituted for the 1 1/2 inch stock. The carbon gear is 1/2 inch wider at the base and 2 inches more spread. Aluminum channel and small aluminum stock alternated.
Engine box dimensions for mounting a DA 150 are as follows: 9 3/4 inch front of the firewall to the first bulkhead on the left side, and 9 3/8 inch from the left side. The engine is offset approximately 2 inches to the left and the engine holes are 5/8 inch from the top of the engine box. Attached are some pictures that may be helpful.
Started to sand the fuselage. I hope to take approximately 1.5 oz off by sanding. The 1/8 inch sheeting will hopefully be sanded down to about 3/32 to 1/16.
09-12-2006, 11:56 PM
#23
RE: 40% Extra 300 Construction by-the-numbers
The zero dihedral wing resulted in just a little bit of opposite aileron and up elevator mix with rudder (3 to 5 % each) but more importantly the yaw is very linear across the full spectrum of maneuvers, to include 3D knife edge.
Weight measured as follows- ready to fly less fuel:
Left wing 3Lbs 11 oz
Right wing 3 Lbs 10.6 oz
Wing tube 14.8 oz (CF)
Canopy/deck 1 Lb 12.8oz
Elevators and stab tube (CF) 1 Lb 13.6 oz
Spinner 9.2 oz (non-lightened backplate)
Prop/hub 1Lb 4.4 oz
Fuselage 25 Lbs, 0.4 oz
Total weight if I added this up correctly is basically 38 3/4 Lbs. This is significantly lighter than what I was expecting.
The airplane flies totally different from the existing Extra 300 I'm flying. This is mostly due to the lighter weight, additional servo per aileron side, zero dihedral. Results have been very favorable so far.
Weight measured as follows- ready to fly less fuel:
Left wing 3Lbs 11 oz
Right wing 3 Lbs 10.6 oz
Wing tube 14.8 oz (CF)
Canopy/deck 1 Lb 12.8oz
Elevators and stab tube (CF) 1 Lb 13.6 oz
Spinner 9.2 oz (non-lightened backplate)
Prop/hub 1Lb 4.4 oz
Fuselage 25 Lbs, 0.4 oz
Total weight if I added this up correctly is basically 38 3/4 Lbs. This is significantly lighter than what I was expecting.
The airplane flies totally different from the existing Extra 300 I'm flying. This is mostly due to the lighter weight, additional servo per aileron side, zero dihedral. Results have been very favorable so far.
09-13-2006, 08:14 AM
#24
My Feedback: (5)
RE: 40% Extra 300 Construction by-the-numbers
Don was gracious enough to give me a few minutes on this plane on flight #2.
Really nice flying plane. As Don notes, the removal of dihedral improves flying characteristics but I think it also looks better. In the few minutes I flew it some things that stuck out to me were:
Nice slow downlines. I assume it is because it is a sizable plane and under 39lbs
Rolls great.
Snaps are easy- I was able to hit snaps right away.
I felt very comfortable with it more quickly than any other plane I have flown, including my own.
It looks to me like this plane is a real winner.
Dave Michael
Really nice flying plane. As Don notes, the removal of dihedral improves flying characteristics but I think it also looks better. In the few minutes I flew it some things that stuck out to me were:
Nice slow downlines. I assume it is because it is a sizable plane and under 39lbs
Rolls great.
Snaps are easy- I was able to hit snaps right away.
I felt very comfortable with it more quickly than any other plane I have flown, including my own.
It looks to me like this plane is a real winner.
Dave Michael
