1:4 1928 RRG Professor

[ARUP]

TJ, sorry for delay in response. I typed one but must have forgotten to hit the 'submit' button. 3/32" hard balsa is sandwiched between two pieces of 1/16" lite ply. The bell crank is 1/16" phenolic. The 'T' nut flange acts as a bearing surface/spacer and a washer to fit the 4-40 through bolt does the same for the other side. The unit is pretty stout!

[ARUP]

I'm in! What are ya building? Gonna do a build thread?

[MarkRobbins]

Mike, I can't wait to pull this up! My new tow plane is on the bench now!

[ARUP]

Thanks, Kevin! You are very generous. I just love to build the old fashioned airplanes the old fashioned way... that's all. It's so much fun flying with y'all that I have to be sure and have models ready! That's the lion's share of my motivation!!!

[ARUP]

Thanks, Mosquito Tim! If I start cutting my ears or things like that then you know my work will eventually be worth something!

[kjkavaney]

Michelangelo would be I think the perfect description of Michael Kelly...you blow us all away with your talent and execution Michael...
Lovely Lovely Lovely...
Kevin

[Mosquito]

Michael, you are an artist!

Tim

[Tango Juliet]

Great timing! I need to make mine also. Is that all 1/16 Plywood?

[ARUP]

The skid got some varnish so it can be attached to fuselage later. The rudder bell crank parts were fabricated. I put a 'T' nut inside one of the ply parts. The large hole is for access to the skid nut and bolt. The 4-40 bolt can act as the pivot. The holes were all drilled off center on the phenolic bell crank so that if I ever run out of adjustment on the clevis I can flip the phenolic bell crank over to get a little more tension. Plastic tubing was inserted into aluminum tubing to make the ferrules. This was bent to guide the cables to the rudder horn (as yet to be fabricated). The bell crank cable holes are 70mm apart so the rudder horn needs the same 70mm spacing. I drew all of this on paper so that the ferrules could get bent appropriately. They got epoxied in place then reinforcement epoxied around them. The last picture shows a nice little area in the nose to hold some lead weight. Waddaya think, Len 10 or 12 lbs?









Bonne nuit!

[ARUP]

Yes, Stephane, you are so right! I had a lot of repairing and reinforcing going on with the main skid and tail skid on the Balestruccio. I think I'm starting to learn what it takes to make them function properly. And... with the Vampyr I learned that good solid fuselage bottom surfaces are needed to protect against short stumps and rocks hidden in the runway. So.... the Professor is getting good bottom side reinforcement forward! I clamped scrap balsa against the keel and sanded the scrap to match the curve and bevel. The scrap was unclamped then glued to the keel allowing for the 1/16" marine ply thickness so the ply fits flush to the edge of the keel (and formers). Other pieces of scrap were glued to the fuselage formers for the same reason. The 1/16" marine ply will sit down in these 'pockets' and be glued nice and secure.The 1/64" 'pretty ply' will go over this. The nose got balsa block to provide support for the 1/64" ply. After this was done 60 grit sand paper on a 'T' sander leveled everything then the Cherry stain put on the frame. I don't plan on any gaps between the 1/64 sheets of ply but... you never know! The stain will hide them if they occur.

I'm going to make the rudder bell crank and route the cables in respective fair leads before closing up the fuselage with the 1/64" plywood. I love this stuff!







Gute Nacht!

[French1]

Skid is always a difficult compromise to balance avoiding it to be removed at each landing or been to heavily fixed to the fuse and on a hard landing to rip all the bottom fuse.
Third option is always to have good landing but quality my vary...at least on mines...

[ARUP]

More pics of skid stuff. The picture showing the Nyloc nut isn't great but you get the idea. The nut just keeps the bolt from dropping out of the airframe. The auto fuel tubing serves as shock absorbers. You can see the slot at the skid's end. There is a thin piece of auto hose under the front end of the skid, too. It's a good idea to allow the skid to 'move' otherwise the mounts might get 'torn asunder' during landings..









More to come!

[ARUP]

A 1/4" marine ply block was epoxied into the rear of the fuselage for the tail skid which will come later. The mounting blocks and hardware for the skid were put onto the fuselage. The front mount has a 'T' nut to firmly attach the skid. The next two mounts have a brass tube bushing to let the bolts travel up/down during takeoff/landing. A Nyloc nut secures the bolt. The skid was ripped from a block of Ash. I had to make multiple passes on my Microlux table saw to get the width and thickness needed. The skid was sanded, soaked in hot water (absolutely use no ammonia unless you don't mind the wood becoming brittle and easily broken) then clamped onto a jig to set the curve to follow the fuselage contour. When dry it was drilled for the mounting bolts then stained H.Behlens 'Nutmeg Brown'. This is a water based stain so it is perfect for staining wood before gluing assemblies. Oil based stains won't work in this regard. The skid is slotted at its rear mounting point to allow movement as the skid rubber hose segment shock absorbers are compressed.

[ARUP]

Dennis, Aircraft Spruce and Specialty has 4 x 4 sheets of 1/64" ply. http://www.aircraftspruce.com/catalo...nnishbirch.php It is the Finnish Birch Ply (metric) Balsa USA used to sell 4 x 8 sheets and they would send them rolled. I can't find a source for 4' x 8' sheets of 1/64" ply anymore.

[DennisB]

Michael. Got a question for you. What’s your source for long sheets of 1/32 and 1/64th plywood? I’m working on a 1/3 ASK-14 and will need ply skins eventually.