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1:4 1928 RRG Professor

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  • #46
    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

    Comment


    • ARUP
      ARUP commented
      Editing a comment
      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!!!

  • #47
    Mike, I can't wait to pull this up! My new tow plane is on the bench now!

    Comment


    • ARUP
      ARUP commented
      Editing a comment
      I'm in! What are ya building? Gonna do a build thread?

  • #48
    Hillbilly white tie? Could be! The first pic is the paper pattern made to fit the nose. 1/64" ply cut a little large, the release area cut into it and fitted then the ply was cemented in place with Ambroid. Wow! The first bit of ply going on the model always gets me pumped! Once the glue dried a scrap bit of ply was abutted to the proud edge of the nose ply then the nose ply sanded down to the level of the scrap. Fitting the top and bottom ply pieces against the nose ply will progress quicker! I had to make sure the nose ply piece was square to the datum line (which is parallel to the top longeron) of the fuselage. Don't want seams 'running downhill' or 'uphill'! The last pic shows the skid patiently awaiting installation! It has three coats of pretty varnish!

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    Boa noite!

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    • #49
      Michelangelo at work here...beautiful stuff Michael...you put the rest of us to total shame....damn..
      kevin

      Comment


      • #50
        Thanks very much Kevin! I hope the information contained within this thread is enough that anyone can use it to build vintage sailplanes! The more vintage sailplanes flying the better as far as I'm concerned! (I'm good at dodging snowballs thrown by glass sailplane fliers! )

        I had some 'split sinker' lead weights lying around so decided to use 'em. Some got pounded with a hammer to various degrees of 'flatness' then they were 5' epoxied into the upper recesses of the frame's nose before the ply put in place. The fuselage sides were used as 'weight receptacles', also. A piece of plastic bag was laid down then some lead pellets were poured in place. A scrap piece of balsa was used as a scree to level and make sure they didn't sit proud of the level of the ply, once added. The lead was (about 100g each side) mixed with 30' epoxy then put back into the fuselage recesses. Once the epoxy cured for each the ply was added. The goal is to maintain room inside the cockpit for some 'spurious' detailing. The full scale plans for the Professor are available for a price tag of around $7K. If I'd hit the lottery I'd get 'em. As it stands there is no room in the budget for that kind of acquisition! A Coverite iron was used to shape the gentle curve in the ply after it was cut and sanded to fit. Paper and light card stock is used to make patterns for these ply parts.

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        Joyeux Noel!

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        • #51
          Christmas Day has been a good one! It even snowed a little bit! After visiting with family and friends more was done to the Professor! More ply added. A couple of large gussets were added to reinforce the aft section of fuselage to the 'backrest' front portion. The instrument panel a it's items were fabricated. There are no photos of it so basic instruments were put on it. The tow release knob was turned using a drill and sandpaper, drilled for the pull rod then dipped in orange dope a few times. The variometer face was drawn onto paper then cut free. The needle was from brass parts included in an 'instrument kit' purchased many moons ago. The other two instruments, altitude and speed, were salvaged from that same kit. I had to paint over English words on them. The needles are free to move. A brass pin was used to capture the needle. The pin was bent downward on the back side of the instrument and excess length cut. The end of the brass acts as a weight to hold the needles fairly stable around the 'zero' mark on the face of the instrument. The glazing was put into a frame overlay then captured by the instrument panel. Holes were drilled in the fuselage bulkhead to receive the instruments before the instrument panel with its glazing was put over them. The holes were painted with black dope. The functioning compass was obtained from a sporting goods store.

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          More pics to follow.

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          • #52
            More pics!

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            The pics are a little blurry... sorry. The rudder cables are going to get installed then the sheeting can pretty much get finished. The fin and tail skid will need to be built in order to finish the ply sheeting.

            Frohliche Weihnacten!

            Comment


            • ErichS
              ErichS commented
              Editing a comment
              Love it..no fancy instrument panel back then. Should be a great thermal machine.

            • ARUP
              ARUP commented
              Editing a comment
              Thank you, ErichS!

          • #53
            Wanna see some 'skin'? More ply skin that is! A better pic of the compass is shown. Too bad it doesn't have a German face dial. The rudder pull-pull cables were run and structure was 'clearanced' for the cables to pass freely without rubbing. While putting ply on the fuselage it was realized it might be problematic getting to one of the skid anchor bolt/nut assemblies. It would be difficult to get my hand inside the fuse to turn wrenches. What to do? A guide tube was rolled from paper using a suitable mandrel (a K&S Wire Bending Tool handle, in this case) so that a 1/4" socket with attachment and extension would fit. Access will be from above inside the pylon. Balsa guide tube supports were made from balsa. The socket was used to align the guide tube while the glue dried. More ply skinning can commence!

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            Comment


            • Tango Juliet
              Tango Juliet commented
              Editing a comment
              Are you getting equal rudder deflection with that linkage? Something about it just looks a little off to me.

            • ARUP
              ARUP commented
              Editing a comment
              TJ, yessir! The servo arm is 90 degrees from the link to the tiller. If the tiller and servo arm were parallel to each other, which might 'look' better, then the throws would be more differential. If the servo arm was a lot longer then you might get some 'wonky' throws at the extremes of travel but for such a short moment it is pretty much equal. Don't over think these things! The 'computer' radio is your friend (even though I have my doubts at times)! lol

            • Tango Juliet
              Tango Juliet commented
              Editing a comment
              Maybe it's just the photo. There might be some parallax contributing to the illusion that it's not all square.

          • #54
            Kevin K... this post is for you, good buddy! The pylon was set up with incorrect incidence as noted early in the build. Balsa was glued as 'backing' inside the pylon then more balsa scarfed in place against the backing. You can see the untrimmed backing and scarfed wood in the background and the finished result in the foreground of first pic. The ply skin will reinforce this fix. This exercise was so the wing sits flush on top of the pylon. The next pics show where balsa was scarfed to the former so that the ply will have aligned seams when added, later. One is of the wood 'before' and the other is 'after' the stain added. The switch mount was made from ply, stained then glued in place. The pilot's right arm will cover it. It's fun to hide the electronic stuff as much as possible so that the casual inspector won't see it and spoil the illusion! Manila folder card stock was folded then strips were cut. The odd ones... or was it the even ones... were removed and saved.
            The strips were weaved together then they were stained. When the stain dried thinned wood glue was painted onto this then allowed to dry. What in the world...?

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            More...

            Comment


            • #55
              The weaving class is so a nice period correct pilot's seat can be made for the intrepid pilot! He needs to be able to work in a comfy office! Who knows what the 'real deal' looks like but this is fun stuff, man! A paper pattern was cut using TLAR technique. Stand offs were made and screwed to the seat bottom and the assembly was epoxied to the rudder tiller support rail. When the epoxy cured the seat bottom was removed so the back rest, as cut using the paper pattern, could be added. The edges were trimmed with stained manila folder stock so they don't 'unravel'. The seat keeps the pilot's 'bum' from interfering with the servos. Don't want a 'goosey' pilot on approach! The pilot likes it!

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              Dobroy nochi!

              Comment


              • JimD
                JimD commented
                Editing a comment
                Very clever...you are the master of detail illusions!!!

              • ARUP
                ARUP commented
                Editing a comment
                Thanks, Jim! Did you see the stereo images?

            • #56
              That looks really great Michael. The seat is exceptional.
              Len Buffinton
              Team Horizon Hobby

              Comment


              • ARUP
                ARUP commented
                Editing a comment
                Thanks, Len! Another one for your logbook coming right up!

            • #57
              Mind Blowing...I needed some inspiration about now Michael...thank you for the GIFT !!!!
              kevin k.

              Comment


              • ARUP
                ARUP commented
                Editing a comment
                You're welcome, Kevin! This is a lot of fun and if it bring pleasure to others then that's even better!

            • #58
              Mad Modeling Mike! Can't wait to see this one in person.

              Comment


              • ARUP
                ARUP commented
                Editing a comment
                Thanks, Chris! What have you on the building boards? The Parabola would be pritt-tee-cool!

              • ChrisL
                ChrisL commented
                Editing a comment
                I was contemplating a joint project with PeterG, a 50% Professor but somebody beat me too it!

                I finally have my router together so I'm bouncing between a Parabola 2.0 or the Manuel Hawk.

                Awesome work on your Professor Mike, it's not as easy a build as it might look.

              • ARUP
                ARUP commented
                Editing a comment
                50%... that would be HUGE! Is there a 50% Professor out there? One thing to keep in mind is that these early birds had no glideslope control. You would have to add non-scale air brakes/ spoilers or program some relfexed ailerons with appropriate elevator mix to kill some lift. Otherwise, build 'em big and fly from a very BIG airfield. I would like to build the Darmstadt D-7 'Margarete' next. It's a cool two-holer! The fin and pylon would be particularly challenging.
                Another Parabola would be cool but if you are like me it is hard to build another of the same type. A Manuel Hawk would be pretty cool! The Professor is tricky around the pylon area and keeping things straight is a 'watchword' for this build since it has lots of straight lines, lol!

            • #59
              I came on this thread a bit too late. The Rhȍngeist was the prototype for the Professor built by Schleicher and was intended to replace the RRG Falke. It arrived at the Wasserkuppe in 1928

              Kronfeld made 4 very importants flights with the "Rhȍngeist":-

              - 30th April 1928: (Probably) the 1st Variometer flight in Gliding-History; starting at the Kuppe with a flight to the Weiherberg and back to land at the Kuppe at the same place he started. The Vario was built into the instrument panel and fitted horizontally and hidden under a leather flap, Georgii, Lippisch, Kronfeld and Nehring knew of it and how it worked.

              - 6th August 1928: The Himmeldung (a mountain at the Rhoen) flight; the first official Vario flight. A handful people of the RRG were involved, including Hirth. For the international scene the Vario is a "german secret" untill 1930 when Hirth travelled the US and Kronfeld toured Britain. See photo attached of the Vario

              - 14th August 1928: Kronfeld's Record flights at the Rhoen Competition; Duration Flight: 7h54min - Course record: 41 km - Altitude record: 660m --- winning the 9th Rhoen.

              - End of January to about 20th Feb 1929: The Rax-Expedition; first international RRG Tour (to Austria), for the first Alpine Expedition. The Tour was lead by Fritz Stamer. Kronfeld made his important flights on the 4th and the 12th Feb.

              In 1929, Kronfeld moved on to the Wien, which was basically an improved Professor. The Rhȍngeist was overhauled and reworked, but it made no further records.

              I have several photos , including the Rax expedition and a 3-view depicting the cartoon image of the Rhȍngeist which was on the fuselage. Apart from the Vario, nothing seems to be known about the instruments on board. The 3-view can be found here: https://scalesoaring.co.uk/VINTAGE/3.../3-views3.html

              Comment


              • ARUP
                ARUP commented
                Editing a comment
                Hiya, VinceC! Thanks for looking in at the build. I'm going to pretend mine is a transition version so the instrument panel and othe ritems can just remain as they are. Just so long as it looks like a Professor in the air that'll be great!

            • #60
              Great stuff, Mike! Great idea on the seat. It all looks lovely. Can hardly wait to see it next fall at our aerotow event. I missed it somewhere, but what glue are you using on the 1/64 ply fuse covering? I used contact cement on my Crested Wren, but then I worried it might eventually let loose.

              Comment


              • ARUP
                ARUP commented
                Editing a comment
                Al, thanks for the compliment! I'm using regular old yellow wood glue. I speed up the adhering process with a hot Coverite iron. I use the iron to bend the ply if needed, too. No water needed. I used contact cement on the Prufling. It works great but if the temps get too high like they did while the model was in the hangar at one of the past Horizon Hobby Aerotows then the contact cement might start letting go. This happened on the wingtips where a curve was forced onto the ply. They stuck back down okay. At 'normal' temps that cement is pretty tough. Wood will break first!
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