1921 Vampyr in 1:4 Scale

[Melchizedek]

Michael, I googled "Jesus Joint" and found some chick rolling a doobie with a page out of the bible.
Me thinks this is not what you meant.

What is a Jesus Joint ?

Kevin

[ARUP]

The stabilator will be removable. A hinged 'tongue' will be attached to the fuselage. The tongue will have a control horn driven by a push rod. The stabilator will have a grooved receiver to fit the tongue. A small nylon bolt engages the tongue through the grooved receiver so that the stabilator won't slide off in flight. This whole configuration needs to be strong, easily secured and slop free... the veritable 'Jesus Joint'! The hinge is brass tube in a tube with side play at a very minimum. The roughened ended portion of the 'L' bent music wire gets epoxied into the spruce fuselage ends thus capturing the inner brass tube. The outer brass tube is the pivot and gets CF with epoxy wrapped over it and onto the 'tongue'. The ply plates are glued into the stab to fit or 'receive' the tongue. It's a nice tight fit. The horn got epoxied into its interference fit slot.

[ARUP]

Hey Kevin, my understanding of the term is that you pray that some portion of a machine or whatnot doesn't break if your life depends on it! If it (the joint, screw, bolt or whatever) lets go then you will go to Jesus! I think the term initially applied to helicopters. Glad you're checking in! Here's more! I made a plug to replicate the soccer ball wheels. Three wheels are needed. The plug was put on a parting board, sprayed with mold release (PVA) then when it dried , glassed. When this cured the whole thing was sprayed with PVA again and more glass put on this. Register marks keep mold halves aligned. When this cured the halves were separated. An interference fit hole was drilled into one mold half to receive an aluminum tube bushing. The other half had a larger hole cut in it so the Reoflex compound could be poured into it. The pour hole was sized to match the sew lines on the scale soccer ball. The first two were pretty easy... just fill with thoroughly mixed rubber compound then let it set up. The third wheel has lead in it. I needed the nose weight so why not hide it in the nose wheel? I poured a little bit of compound inside the mold then kept sloshing it around until it got pretty thick. Lead shot was poured into this then more compound mixed up and poured in. I let this set up. It worked pretty good. The weights are shown. The two rear wheels weighed exactly the same at 69 grams each!

[ARUP]

Here's the ReoFlex40 product. The stab was statically balanced with lead shot. Some fabric was draped over it to approximate final weight while doing this. Allowances were made for finishing fabric. When done the stab balanced slightly LE down at the hinge. Perfect! You can see the stab 'keeper bolt' block in the middle of the underside ply plate.The fin/rudder assembly built to be removable. Aluminum tube receivers put into fuselage. You can see the secondary stabilator push rod from the fuselage 'walking beam' to the stabilator horn. This gives a better push rod egress angle. Looking at photos later I found the horn should be on the upper surface. Oh well. The fin and rudder can be separated with a simple piano hinge pin if need be. For storage they are removed from the model as a unit after disconnecting the pull-pull cables.

[ARUP]

The rudder horn made of bent wire, soldered and with brass tubes soldered to ends. The tube ends are flattened and drilled to accept pull-pull cable shackles. This was painted black. The pull-pull and push rod bell cranks were fabricated from micarta, brass tube-in-tube and music wire. You can see the primary stab push rod connected to its bell crank. A release was fabricated. This one had to be modified because the washer that was soldered onto the end broke loose. From now on I'll bend a loop in the wire to make the connection to another link to servo or make it a direct connection to the release servo. Rear wing attachment bracket and blocks epoxied to fuselage and center wing section. The fore wing to fuse attachment is via the sheet metal 'tongue' installed earlier. It engages a pin in the fuselage for quick assembly.

[ARUP]

Struts, fittings and blocks were fabricated and attached to the wing and fuselage. The strut was made from music wire. The ends were heated cherry red, hammered flat, drilled and then tapped for 4-40 bolts. Do this work while listening to Verdi's 'Anvil Chorus'! The ends were dressed to a round profile then the struts and brackets were cleaned and painted black. The hatch construction started. A lower 'keel' added to forward fuselage. Basic 'bones'! You can see the washout in the outer panels.

[ARUP]

Now that the basic structure is done all that is left is to add bits and pieces like covering, hatch bits, radio and etc. The wing brackets need balsa 'fairings' so the fabric can attach around them. CF tow epoxied at nose bows for reinforcement. A tool-less hatch release was fabricated. The spring loaded device keeps the hatch connected to micarta hooks. It is a simple matter to slide hatch forward then off. Putting hatch in place requires that you use index finger to move spring loaded device forward until it clears its stop (fuselage cross member) then dropping hatch down onto the rails. The device automatically pushes hatch rearward. It takes longer to describe than to perform the exercise! The covering started with tail feathers and the 1/64" ply skinning started at the nose. I used contact cement for the ply to fuselage adhesion.

[Guest]

Simply amazing build quality, what a hand crafted beauty. This is the kind of building that inspires more, thank you for reposting.

[ARUP]

Thanks, Thompson! When folks get to lookin' around and responding it really fires me up, too! I really appreciate everyone's input! Here's more. What I thought was some sort of porthole with a cloth 'window' is actually a hatch. Oh well... it's a porthole with a cloth window on my model. I started putting more ply skins in place. Paper as well as card stock was used to make templates to cut the ply. Tedious but it works. CF tow was put under the ply nose wrap around piece for strength and all held together with epoxy. That's why the clothes pins used. Pretty much everywhere else got contact cement treatment. The Koverall fabric stuck down using Stix-It.

[ARUP]

Here are the wing panels getting Koverall. The 'masking tape technique' was used again. The bottom surfaces were done first. Covering put on the center working outward. When fabric attached to the bottom it was wrapped over the TE and onto the top. The covering was put 'on the bias' for the outer panels. The weave runs diagonally across the span. This was done to allow for 'warperon' flexibility. You can see the weave direction in the picture. The seam is at the LE and is covered with a perimeter tape (if memory serves me for that's my usual finish technique for seams). The 'scale' structure really shows through the fabric and is why I like to use it.

[ARUP]

Wheels, their axles and supports fitted into fuselage. The front beams are micarta. The rear wheels have spacers to keep them from moving laterally on the axle. 1/64" put onto bottom but it was found to be too fragile. This was eventually replaced with glass cloth and 1/8" marine ply. The under surface really takes a beating, especially with my arrivals! Wheel wells were built around the wheels inside the fuselage. I didn't want debris being kicked into the fuselage. Shackles for the rudder pull-pull cables are Proctor Enterprises items painted black. I made tiny cotter pins for attaching the shackles to the horns but a straight pin is shown performing this function in the photo. To remove the fin/rudder just remove cotter pin, disconnect the cable, put cotter pin back on shackle for safe keeping then pull fin/rudder assembly off fuselage. After the Prufling, which takes an hour to assemble or disassemble, I wanted 'quick'!

[ARUP]

Shown is the front wheel well boxed in place. The 1/64" skins were finished. Koverall fabric put on top and bottom using Stix-It. The wings and fuselage got multiple coats of nitrate dope brushed to seal the weave of fabric. The 'Vampyr' name was hand drawn and then masked. Clear butyrate dope sprayed to seal the mask edges against 'bleed under'. Then white dope sprayed and mask pulled away once the dope tacked up.

[Melchizedek]

I remember Don R saying " you build such cool planes". The quote is loose by memory. But I could not agree more.

You mentioned the "Masking tape technique " on covering. Sorry if I missed it, but could you elaborate ?

Kevin

[ARUP]

DonR is a heckuva guy! He is an awesome builder, too! His Corsair blows my mind every time I look at it. Your Weddell-Williams is coming along nicely I might add! The 'masking tape technique' can be see on the 2nd page post #23 of the Balestruccio build. Back in 'olden times' when these things were being built money was pretty tight. The builders saved money on fabric by not covering everything. For example, they would only cover open structures but not sheeted portions of wings to save money. It's difficult to get fabric edges straight and aligned with minimal contact area at these scales. What I do is lay down masking tape along a sheeted portion of a wing with, say, a 1/4" portion showing that gets the fabric adhesive. I lay the fabric down and 'burnish' adhesive through the fabric covering and onto the exposed portion of the sheeting which has just one coat of adhesive. This encapsulates the fabric onto the structure. Once the fabric is applied the masking tape acts as a guide for the X-acto knife. When finished trimming excess fabric just pull the masking tape! I use masking tape on one side and sometimes both sides of cap strips that need adhesive. It really makes for a clean crisp application of the adhesive. The tape can be re-used a few times, too. When I 'do' cap strips I'll advance to the next third or fourth one and by the time those are dry I pull the tape from the first one and put it on for the fifth cap strip. It progresses quickly and the results are very satisfactory.

Nitrate dope was brushed onto the structure to seal the fabric weave. I mixed up some butyrate in a color using TLAR method to try and match colors seen of the Vampyr hanging in a museum. The warp action diminished due to the stiffness effected by the dope. Bummer. Nothing ventured, nothing gained, so I started building outer panels for the original 1921 version of the Vampyr that had ailerons. I think I have a remedy for the 'warperons' but have been too lazy to try it.

[ARUP]

The full scale cockpit enclosure was leather. I put silk on a frame and painted several coats of brown dope on it. The 'leather' was taken off the frame and the edges folded then sewn with brown cord. This was epoxied to the cockpit sides. It doesn't look much like leather! It looks like plastic tarpaulin except instead of being blue it's brown. So... if ya wanna know how to replicate plastic tarpaulin then here ya go! A tip template was made and used with the root template to makes new ribs to build aileron version outer panels.