New Scale Model Build-Navaho

[mpitfield]

I don't know abut the rest of you but I am going through "Navaho" withdrawal...I need some pics, fast!

 

[hornet driver]

Agreed!!

 

[rocketgeek101]

I don't know abut the rest of you but I am going through "Navaho" withdrawal...I need some pics, fast!

Well spoken indeed!

 

[JumpJet]

Not a whole lot more to show than what you’ve already seen. This past week I coated all the body parts with a coat of Bob Smith Epoxy Finishing Resin. Gave it a good sanding, sprayed on a couple coats of Primer, sanded some more, covered the entire thing with Bondo Spot Putty, sanded 99.9% of it off, primed and sanded a couple more coats. This is the part of ANY build I HATE. I love sanding wood, but I hate sanding resin and primer.


One image shows the air intake. It still needs more sanding and shaping. Another photo shows the fit between the wing and fuselage, while another shows the exhaust outlets. Then there is of course the over all grey colored fuselage in another image. Hopefully tonight I will get around to cutting out the wing to accept the torque rod assemblies for the elevons. I can then finish up the wing and get it primed.

This finishing step is adding a TON of weight to the model. It will easily add four ounces of weight, maybe more. The Problem I have is it needs to be as perfect a finish as possible to get the craftsmanship points. If you were to rotate the front of the model inside your fingers you can feel that it has some high spots, so I’m trying to get ride of them with primer, which adds weight. If you were to just look at the model from a foot away you could never tell so maybe I’m being too particular in this aspect of the finishing process.


John Boren

 

[Cookie the Dog's Owner]

This is already one of the most impressive models I've ever seen. Your commitment to perfection is awe-inspiring.

 

[TopRamen]

Phenomenal!!!

 

[powderburner]

It's going to fly and 50-50 chance it crashes on it's first test flight.

If it crashes, I will be crying.

Back when I was a kid in Davenport, the local model airplane clubs used to hold a big contest every year at the Mt Joy airport. I saw a giant B-36 fly. The control-line "combat" contests were always fun....for spectators. But the one time that stands out in my memory was when a beautiful P-61 (about a six foot span) with a highly detailed exterior and finish was flown and crashed. The guy sat down and cried right there in front of everyone.

I expect to hear of FAR better flight test results for this.

 

[JumpJet]

Just one boring image for tonights update. The elevon torque rods have been installed and the top and bottom of the wing has been glassed with 3/4 ounce weight fiber glass cloth and Bob Smith Epoxy finishing resin. It should only take a couple coats of primer to get the wing ready for paint. As yo can see I still need to trim the glass cloth around the edges and sand the wing. I simply hate this part of ANY build I do. I love carving and shapping balsa and foam but I simply hate glassing, primering and painting. Hopefully I will start on the booster this weekend for a change of pace.



John Boren

 

[JumpJet]

It?s been a while since I?ve posted anything new on my Navaho. I spent a couple of weeks cleaning up the house, especially my workshop for the Rocket Clubs Christmas Party I hosted last week, then took another week off looking at my clean workshop before I totally destroy it again during my next round of building.

The only new thing I did was to glue all the formers on the BT50 center body tube. The plan is to plank this assembly with the same wood sticks I covered the winged portion with. I will then figure out a way to mount it on my wood lathe and then sand it round with a long sanding bar. The body tube coupler shown will get cut down in length by half since I simply don?t need the extra weight. The coupler will then go into a 12.56? long piece of 3? OD body tube. The rear of the body tube will then get another built up section containing the two 29mm motor mounts, one mounted at a 3 degree angle with the other at a 4 degree angle. Hopefully I?ll get the motor mount section assembled tomorrow so it should make more sense then these written words. This part then gets the same wood planning as the nose section.

John Boren

 

[JumpJet]

Below are the images of the two cluster motor mount for the Navaho Booster. Along with the section of the real Navaho for you to get a better idea what the finished part will look like once it has been planked with the balsa. The small notches in the two rear centering rings are to locate the four fins of the booster. The 3" OD body tube the coupler will slide into will need to have an elliptical cut out in it so the tope motor tube can slide into place. This exposed motor mount tube will then be hidden by the fairing the Navaho Winged Portion rests on. The reason for the two forward extensions of the motor mount are both to help align the motor mount in place and to also get the ejection gases further forward in case I wish to use them to help deploy the boosters parachute.

John Boren

 

[aerostadt]

Looks terrific as usual. Who is cutting your parts?

 

[JumpJet]

Lo

oks terrific as usual. Who is cutting your parts?

I have access to a laser

 

[JumpJet]

This is how the three pieces of the booster go together. Now I just need to spend about eight hours planking the outer surfaces, sand everything smooth then assemble the pieces.

I went ahead and Plank the rear motor mount section. I was able to cheat a little and use a piece of sheeting on the side. It took a little over 2-1/2 hours to do this.


John Boren

 

[Daddyisabar]

Shiver me timbers. Ya gettin' the kink just right there laddie!

 

[JumpJet]

I did some rough sanding on the motor section tonight plus I started fitting the fins. Since the angles and shape of the fins are a little hard to determine I thought I would make some sample attempts out of thin foam sheets before cutting the final wood pieces.

John Boren



P.S. Looks like I've got the shape of this thing all wrong. Back to the drawing board.

 

[mpitfield]

Watching this build has been a real treat...love it and can't wait to see it fly!

 

[JumpJet]

For last two nights I’ve been working on the forward booster section of the model. I abandoned the built up version and instead turned to a balsa version turned on my wood lathe. Not having the right size blocks laying around the shop I instead decided to glue 12 pieces of 1/4” thick 3” wide balsa sheets together. I used 30 minute epoxy to make two sets of six laminates. Once dried I tack glued both blocks together so they could be later separated. One image bellows shows two cones I turned, one last night one tonight. The version last night just didn’t come out right, “Out of Round”, so after a chat with the Sandman I changed the way I mounted the block on my lathe and tonight’s version came out very nice. I for one don’t have the ability to turn a 3” OD part out of a 3” wide block so as you can see I had to add four filler pieces around the edge that matches up with the body tube. This worked out ok. The image with both nose pieces shows one hollowed out. This will be done on the good one as well but I will most likely make the wall thickness no more then 3/16”. I need to keep the weight down to get this bird under the 3.3 pound lift off weight.

One more day of work and I’ll be off for the next two weeks so hopefully I can at least get all the assemblies completed and primed so it looks like a Missile ready for flight.


John Boren

 

[hornet driver]

WOW, Just WOW!!!

 

[JumpJet]

Just one image for tonight! This is the inside of my second nose piece. When solid it weighed in at 9.4 ounces, hollowed out its only 4.4 ounces. Inside the cone you can see the Xacto tool I used to hollow it out with. This is my second favorite hand tool to use in the shop. To the right of the image you see the tube coupler that will go over the end of the shoulder. I will most likely cut the coupler and balsa shoulder down a good inch since the nose gets glued in place and I simply don’t need the extra weight. At the top of the image use see the rear of the booster with the Ply Center fin parts test fitted in place. The bottom of the image shows an image of one of the new Estes ARF fins. This thing makes a Great Epoxy spreader

John Boren

 

[cvanc]

I am in awe, sir. Just amazing work. Can't wait to see it done and in the air.

 

[JumpJet]

I cute parts out today for the top fairing piece that the Navaho Winged portion rests on. I will have to contour the top of it to match the bottom of the winged missile but I first need to start glueing parts in place.


John Boren

 

[kpklein]

John, I do'nt know what to say. Are you sure you realy, REALY, want to fly it??? If it where me I would give it a few coats of varnish and display it as is. You must have built a few boats I guess.

 

[JumpJet]

It's going to fly at least once, hopefully more if it makes it past the first flight.


I decided to switch gears a little and work on the booster fins. I created them just like the fins for the winged portion. I used a 1/16" plywood core with balsa laminated on both sides. By cutting the parts along where the parts create the high points of the diamond airfoil shape you get a natural reference when shaping the diamond airfoil. I also align the wood grain along the leading and trailing edges. By doing this it makes shaping easier plus the added bounces of antiwarping of the part. If you cut these parts out by hand be sure to apply black marker to the edges where the wood glues together. This helps highlight the line. Since these parts were laser cut I had the burning of the wood to help highlight the joint line.

After the balsa parts are glue to the plywood, I tapered the balsa from root to tip too the correct thickness giving me a wedge shaped fin. Next the leading and trailing edges got their bevel. There’s between 2-1/2 and 3 hours of work just gluing and shaping these parts. I still have a couple mores hours to go adding the base parts to the fins.


John Boren

 

[aerostadt]

This is just a gorgeous model. Even the parts laid out before assembly are fun to look at. I never realized that this missile had so many curves and contours. Even the booster shape is complicated and I didn't know that it had two engines. This thread has been a real education. I am still dreaming of building this model some day. If I ever do so, my model will pale in comparison to this detailed masterpiece.

 

[JumpJet]

Took a while but I now have the lower tapered sections added to the base of the fins and also made two additional bases to add to the top of the boosters body. I still have more final sanding and fitting the booster. I will most likely do some prefinishing to these parts before gluing them in plance to make life a little easier on me later round.

John Boren

 

[Cookie the Dog's Owner]

This is looking soooooo cool......

 

[JumpJet]

It’s starting to look like a Navaho Missile Now.

Before gluing on the balsa nose cone I removed 2” of length from the shoulder of the cone. This saved me .6 ounces. or weight. The top Tunnel or what ever you want to call it is now glued in place on top of the body tube up to the point where the balsa nose starts. One image shows the long taper needed where the rear of the tunnel part matted up with the sides of the body tube. The top rear of the tunnel was filled in with a piece of balsa and then sanded to shape.

I made a paper template to locate the forward canards on the booster. They are placed at a nine degree angle down just like the real one. I still have lots of finish work to do to the parts before the rest of it gets glued permanently in place but I just had to see what it was going to look like stacked together. As seen in the photo the entire model weighs in at 22 ounces. Even though the finish is going to add a good deal of weight I should still be under the limit of what two Estes 29mm Estes Black Powder E16 motors can lift.


John Boren

 

[Rrwjr]

I can only say this after following this thread. we're not worthy

 

[Daddyisabar]

Navaho, be thy name. . .

 

[jazzviper1]

That's AWESOME.
I want one!