1:4 1928 RRG Professor

[ARUP]

All of the shear webbing has been installed! Whoopee! That was a bit of a boring job. I was going to actuate the ailerons via a torque rod with cranks to drive cables to the aileron horns but there isn't enough room for the outboard cranks inside the 'D' box portion of the wing. The ailerons have two set of horns connected to cables. One is only 3 ribs over from the outer panel root end and the other is 11 ribs out. So... pulleys and cables will be used... just like full scale! Waddayaknow! A lot of time was spent running dummy cables to get the lead outs or ferrules installed. 1" diameter pulleys were used. The outer aileron horns have pulleys stacked one above the other and the inboard ones have them separated. The last two pics not only show the inner end pulleys but the outer ferrules pre- and post- installation. More stuff has to be done but I spent a lot of time on these little details!









More to come!

[stevekremer]

Pretty Slick!! Nice job!

Steve K

[ARUP]

Thanks, Steve! Glad you are enjoying it!

[Tango Juliet]

Wow! This is really going to be nice. Where'd you get the pulleys?

[ARUP]

I paint outside!

[Tango Juliet]

You also don't have the high humidity I get down here on the coast. There's only a couple of times a year wen I can paint outside without the humidity ruining it.

[ARUP]

It gets pretty humid around here. I lived in Houston TX for 11 years and know what humidity is! I paint with dope. If it blushes I just buff it some before clear coating. Usually, that isn't needed. I let the model gas off a few days (indoors) before clear coating. I can't comment on any other paint methods.

[ARUP]

Servos in the center wing section will drive push rods. The push rods will connect to bell cranks at the root ends of the outer panels. When installing the outer panels to the center section the ailerons will be free to droop until they get connected and the wing panels are pushed together. I used this to advantage when setting up the bell cranks and cables so that the end of the bell crank will protrude a bit from the root end (pushing the bell crank end into the wing will raise the aileron) , facilitating the connection to the push rod! Sometimes I surprise myself!

Here are the components making up the bell crank. It is made from 1/8" phenolic sheet. The aileron horns at the inner end of the wing panel will be 30mm long and the ones at the outer end of the wing panel will be 25mm. This is reflected in the spacing of the holes on the bell crank. A little bit of 'Ackerman steering geometry' was built into the design. Also, adjusting the cable tension will be by the simple expedient of twisting the cables one way or other. I plane on making aileron horn connecting shackles of various lengths to help with any adjustments in tension, too! When the other wing panel gets all of its 'acruitments' and the 'rea' cables get run then the 'D' tube portions of the wing can get closed up.







Stay tuned!

[ARUP]

The bell crank assemblies were mounted then the cables' runs were double checked making sure the 'pass-through' holes in the ribs for the cables were adequate. The wings' false TEs and ailerons' LEs were cut from 1/4" x 1/8" spruce sticks. The second picture shows a taper cut into these spars so that they can fit the tip better. A straight edge was used for alignment to cut the slots in the ribs for these to fit. The 'cutter' was just an appropriately sized hardwood stick with sandpaper glued onto it. The slot was widened a bit to account for the hinges. There are 10 hinges per aileron. The hinge positions were marked onto the spars and the table saw blade was set to cut the hinge slots on top of the spars so that the hinges are flush to the top surface. The hinges were prepared for being attached to the wings in that they were shortened, an extra hole was drilled so the epoxy could ooze through and the hinges were scuffed with an X-acto knife so the epoxy can 'grab' better. The hinges have been glued in place. The ailerons can be removed for servicing by removing two long hinge pins for each. Next, strips of CF tow will be epoxied over the top of these so that the possibility of them tearing out will be minimized (I hope!). When this is done balsa and 1/64 ply cap strips will get put onto everything after a few more elements are added.






The last two pics should be reversed. One is pre-epoxy showing one of the long 1/32" wire hinge pins.
Later!

[Dion Dunn]

Looking good Michael. Must be nose operation season. I had two chunks taken out of mine recently, but both tested negative. Damn Irish skin.....

[ARUP]

Thanks, Dion! Were there any models you just had to have at the Toldeo show? Yep... Irish skin. My nose has to get 'de-chunked' even further. I wasn't so lucky. Luck of the Irish...sheesh... who ever came up with that!!!!

[ARUP]

More stuff! The first pic shows where/how little segments of CF tow were epoxied over the hinge 'ears'. The second pic shows three stages. On the left side of the pic you can see shear web in place. The shear webs are put on inside portion TE of wing and on inside portion of LE of aileron. The center part of pic shows balsa against shear webs and this clamped until glue dries. The right side of the pic shows the wing waiting for its shear web. Once the shear webs are in place the cap strips can be added. Then the 'D' tube gets closed up after installing the horns and cables. When that is done the ailerons will get cut free from the wing and finished at their LEs.



Buenas noches!

[Dion Dunn]

Honestly, nothing jumped out at me but I wasn’t up there looking for another airplane. One gentleman had a room full of giant scale sailplanes in the swapmeet area, but that’s all that caught my eye.

[ARUP]

All the shear webs are installed with one wing. Next is to install the 'false' ribs or whatever you call 'em. They are to maintain the top surface foil and don't touch the bottom surface covering.



One or two get glued then sanded fair to the others. The masking tape protects the main ribs during this stage. When they are finished everything get sanded again in preparation for cap stripping.

[ARUP]

Ooops! No cap strips until the diagonals in the aileron are installed. The diagonals were let into the structure 'a-la-egg crate' fashion. These were made proud of the surface then sanded back to the level of the main structure. The other wing will get all of this work THEN the 'D' tube and cap strips will get put in place after the aileron horns are fabricated and installed.





See ya later!

[ARUP]

Both wings are at the same level of construction. Aileron horns, cables, 'D' tube sheeting and cap strips the rest of the week.



C ya!

[lenb]

Now for the tedious work....

[ARUP]

That's right! lol

[ARUP]

False ribs were put onto the center section, too! I saved it for last since it was the easiest. A bunch of false ribs were cut along with supports to attach them to the rear spar. After the glue dried these were all sanded fair as shown in the last picture.







Later taters!

[ARUP]

I keep talking about 'D' tube sheeting and cap strips but I ain't there yet! The strut attach points were fabricated from sheet steel. They were mounted to marine ply then epoxied in place on the center wing panel. The wing 'connectors' were also made from sheet steel. These will keep the wings from sliding off the wing tube. An anti-rotation pin and its receiver tube were fitted, too.







more...

[ARUP]

More...







This joiner system works pretty well on my other sailplanes so I'm using it again! A 4-40 bolt just drops into the holes to keep the wings together. A gap cover 'a-la-full-scale' will keep the loose connector bolts from falling out. With all the struts and bolts and fittings (oh my!) I try to keep field assembly easy!