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    #61
    Well I am having a ball , MOHA is out playing her Mahjong so I am sanding like crazy . Those who have looked or even download the plans from AstroBoy will notice the engine pods are not square boxes, equally in real life the 4 x Rolls Royce Conways do not have square exhausts. First get the two tapers on the bottoms as near as the drawing (my trusty T bar made this an easy job), then you will note the wing is two pieces of 5 mm Depron so we can sand a nice taper down to the lower 5mm on the top side of the wing. Angle and round off the corners, shamfer and it now looks more the reverse thrust clam shells of the Conways.

    I checked the springiness (not an English word) and control of the elevons and decided it was too much. Modification time again , this time an easy one to drop two 150 mm extension leads into the wing so that the servo's can be mounted on the side of the engine pods. Another little gem I learnt from a Robbe Dash7 model was to cut the slots (inside the engine pods and on the underside of the wing), and then use a short length of 1/8" dowel to make the slot under the engine pod side by keeping the dowel on the bottom of the slot and gently pushing. Two fillets and as we would say Bob's your uncle, just need to sand smooth when the glue has dried.

    I used extension leads even though the HS55 servo lead is long enough, you never know if you may strip a gear have to change the servo lah..

    Last tip of the day before I get back to sanding , those access hatches 1/32" Lite ply as can be seen and then a small 5 mm piece of Depron for the screw to go into in the engine pod. Here is the cunning part if you do not have any oil burner models ask a fellow modeller for a piece of fuel tubing, open up the hole in the Depron and glue the tubing in with the UHU Por. Your self taping srew just loves that flexible rubber and if it ever wears replace it. The nice thing about using this method is you will not see the screw head. Now for the big fun the leading edge of the wing to get a aerofoil not just a rounded edge, more when I surface from the Depron dust........

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      #62
      Well sadly I will not complete the wing tonight as the MOHA is due home soon, however we have "moved along" as the Americans say. Spent a fair amount of time thinking about that beautiful leading edge and just how easily it will get damaged, either by me or the MOHA when she cleans out area 617 of the Skunk Works. I spoke to AstroBoy who suggested using what I call packing tape which I have seen used on the Screamers of Edmond, too me this seemed like a half measure. We have gone to all the trouble to get beautiful lines shapes to put packing on the wing leading edge it just did not seem right (OK I know I am old fashioned). So like my F-15 I decided to add a balsa leading edge with a difference, in the case of the F-15 the balsa forms the entire leading edges of all the surfaces, while for the Concorde I just wanted at the most a 1/8" strip to form the round part of the leading edge.

      So into the stores to find some medium hard 1/8" balsa sheet which I then made into 11mm wide strips for the leading edge using the balsa stripper (the black thing in the photo). If you have purchased balsa you will know that sheet is very reasonably priced to any strip or square, and using the stripper you can make whatever size strip you want . It handles sheet up to 1/4" and uses an ordinary disposable knife blade.

      Being this is going to be my wing "bumper" for my returns to mother earth with the help of Mr. Gravity, I have used Alphatic / PVA glue to bond the balsa to the Depron. A final shaping using 80 grit of the Depron leading edge gives a nice rough surface for the glue to bond to, loads of strips of masking tape to hold it in place and tomorrow we will have a balsa leading edge.

      This will be then sanded to form a 3mm semi-circular edge with an aerofoil taper for about 3/4" from the leading edge to the full wing size, I am chuckling already more sanding tomorrow night, going to go negative brownie points again...

      For those of who plan to make a Concorde one thing I would suggest which is not shown on the plans, and that is to use 1/4" triangle on the inside of the bottom of the fuselage. the fuselage is very long and will flex quite a lot without it until it is glued to the wing (the dreaded hanger damage).

      Finally for tonight what have I used so far?, 3 x sheets of Depron (5 mm from Art Friend), 2 x lengths of 3/8" triangle, 2 x lengths of 1/4" triangle, 1 x 1/4" medium balsa sheet, 1 x 1/8" medium hard balsa sheet, some off cuts of 1/32" and 1/8" Lite Ply and of course 1 x tube of UHU Por glue.

      Comment


        #63
        By sheer luck the MOHA had to go shopping so I had 90 minute run at sanding.. . The leading edge has now been rough shaped down to 150 grit and looks OK to me so now the real mess starts with the going up to 800 / 1000 grit sandpaper to get a nice smooth finish. It is hard to see the balsa leading edge but I can assure you it is there about 3/16" high x 1/8" deep which was my goal.

        Once I have done the fine sanding it will be back onto the fuselage again to repeat the sanding treatment prior to the wing join. There is also the task of making a hole in the tail cone for Rx aerial lead, I have some long drills so that should not be too difficult one I get the drill started, need to do this task by hand no electric tools.

        You may think that well he has almost finished the model , well depending upon what you are aiming for this could be true. However I am aiming to get a better finish than my F-15 so I plan to spend some more time on this. There is of course the fuselage hatch to be done so we can get at the Li-Poly pack and the receiver, to do this I shall do a static build to see where the hatch has to go (all the bits and bobs) and then prepare the fusleage accordingly I will show this when we come to it.

        So here are some pictures of the rough sanded wing, you will note I have only removed the paper template where I need to work as this will save too much damage to the Depron and associated dressing afterwards.

        Comment


          #64
          I decided to brave it and weight the beast, fin, tail and wing tipped the scales at 270 grams or in my world 9.52 ounces, not too bad as those motor cables are heavy . So back to the MotoCalc program to see what I had estimated, too my surprise I had estimated a raw airframe, wires and servo's at 10 ounces from a spreadsheet that I use. The motors (2 x AXI 2208's), Castle Creation ESC's (25A), 1,500 x 3S1P Li-Poly come to another 7.4 ounces, so I am at 17.4 ounces or 493 grams, which gives a wing loading of 7.8 ounces/sq. ft, so we have a Park Flyer and not a Park Brick

          From all the previous models that I have made the worst case increase in weight from paint and alike is 30% but usually hovers around 25%, so we have a worse case airframe weight of 13.3 ounces. Loading all these numbers back into MotoCalc gives me a wing loading of 9.3 ounces /sq.ft, 1058 ft/min climb rate with a top speed of 44 mph and a 10.5 minute duration on 6" x 4" APC propellers. I leave you guys to change these numbers into your favourite units.

          So my build objective should be achieved of a wing loading of less than 10 ounces/sq. ft and we should still have a Slow Flying Concorde Park Flyer.

          Comment


            #65
            BINGO! Dennis! You did it!, those statistics sounds very promising! But please go easy on the paintwork!

            All in all, i'm very confident this concorde could be flown nice and slow and yet would be on step once full throttle is applied, you are enjoying this build aren't you!? I think so! Cheers!

            Comment


              #66
              Thanks Mr. Designer, I have to say the finishing is the big worry as you can add ounces / grams at Concorde Mach2 with the greatest of ease. As I said in an earlier post I want to try the Chris Goulds finishing method, so plan to use that segment of fuselage I made at the beginning of thread. So it is getting close to experimentation time again, and I will let you know how it turns out and also how succeeded or not at the case may be.

              Out of interest how did you calculate the CoG position.?, as this is going to be important when I do the static initial balancing to determine the fuselage hatch size. I want to keep the hatch as small as possible yet with enough room to do battery changes and if ever neccessary Rx swap out's or crystal changes.

              Comment


                #67
                The focus tonight is back on the fuselage and I prefer to do the fine sanding in daylight (my eyes are getting dim....). Before we can join the fuselage to wing we need to prepare the fuselage a.) for the Rx antenna and b.) for the access hatch, it may turn out that I can use the front box area just in front of the wing but I do not want any surprises once I have done the join.

                I used a 3mm x 8" (now there is a mess of units..!) long drill to make the hole in the tail cone for the RX aerial, and just finished it off with a long piece of 1/8" dia piano wire. You will note that I have used a pushrod inner which will be inserted when the model is finished to draw the Rx antenna out from the fuselage to the tail cone, nice a clear from those 6" dia grass cutters. The tail cone has a nice rounded end which I had not done on purpose as this will be made once the model is finished and prior to painting.

                You will also see in the picture I have cut holes in all the fuselage formers, no I am not saving weight but this is to allow the Rx draw tube to go the nose if neccessary. You will also notice a model knife resting on the bottom edge, the reason for this is that when and if we cut the top hatch there is not going to be a solid former in the way making it almost impossible to get the hatch off without damaging the fuselage. The knife blade will have to go through any formers that just happen to be in the way to make the hatch.

                The picture is lousy appologies for that, I am blaming the Sony camera Macro mode or should I say what Macro mode .The nose and the main center part of the fuse has already been sanded to 600 grit but I have left the tail cone only rough sanded so that I can blend the wing training edge to the fuselage and also that nightmare wing belly pan. So fingers crossed we may be in wing joing and rigging mode later tomorrow.

                Comment


                  #68
                  If you get a kick out of sanding then I would suggest a Nigel Hawes Bae Hawk, this uses 1/4" sheet laminated which you then sand to aerofoil shape. This was my first attempt a pusher models , it weighed a Tonne although the finish was nice Needless to say it flew like a Park Flyer Brick but was good fun, now I wonder how much it would weigh if I made it out of Depron.....?

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                    #69
                    Dennis,

                    Great job on the exclusive.!

                    Hope you are watching the oxygen intake while sanding down the artboard. don't forget to put on protective mask.

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                      #70
                      I have the protective ear plugs for the MOHA but not the protective mask, which actually should be worn especially when using the finer sandpaper. Even the trusty vacuum has trouble getting rid of that fine dust, and I end up using Tack Cloth to clean the foam and area 617. Thanks for the reminder I should invest in same

                      Comment


                        #71
                        Hi Dennis, the CofG position was drawn based upon it being slightly forward of the main landing gear, it's a gut feeling , but should be quite close
                        We should do a glide test before maiden flight

                        Comment


                          #72
                          Another big step achieved this morning the sand down to 400 grit has been totally completed and the wing is now joined to the fuselage . I used 30 minute Epoxy applied to the 1/4" traingle applied with an Epoxy brush to get a thin even spread of Epoxy.

                          As one would expect nothing goes as planned and the wing belly proved to be no exception deciding to fracture during the alignment and trimming process . Still all is recoverable and this part of the model is quite fragile and heavy fists was not treating it in the manner is desired.

                          Once the glue had dried for the wing mounting to the fuselage the wing underbelly was then glued in place. So it is really starting to look like a Concorde now . This fin is still just pressed in place as we have to make all the curves between the wing and fuselage blend smoothly.

                          After that has been completed it will be the final sanding and dressing those hanger bumps and rashes, insert the fin and align and then we are set for the next major step prepare for finishing and painting .

                          The attached pictures show the wing after joining and the underbelly in place, ready for the next steps.

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                            #73
                            The one before the final sand has been completed and everything is now glued in place, so apart from any dings of which I managed on the nose , it will be one more rub down and out to the paint shop. After painting it will be decals and fit the control surfaces.

                            I have mentioned the Chris Gould's finishing method and I used the test piece for a trail and the weight went up by about 20% before painting , how ever the surface finish is just great.

                            You essentially water down white glue to 60 / 40 ratio and then use this to paste light weight tissue to the foam. You need to put a some cake colouring juice into the mix otherwise you cannot see where you have pasted. Once dry you essentially have a PVA surface to paint so a gentle rub down and voila.

                            The results after painting were like your shiny car in the car park, but a price to pay 35% on the test piece. On the plus side the tissue and glue adds strength to the Depron so the Depron is no longer prone to dings and the dreaded hanger rash. I have used the Brown Paper covering method same technique but that is even heavier.

                            So that is my reason for no going this way this time, I really wanted the Concorde to be a Park Flyer, and I would rather have the ability to add a bigger Li-Poly with its associated weight should I need to than start off heavy.

                            The other option I have is just tone down the balsa edges which would be even lighter, somehow that seems like a half done job to me.

                            So here you are the unpainted Concorde.

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                              #74
                              She's Beautiful Dennis!

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                                #75
                                Thanks AstroBoy, I cannot print what the MOHA said returned today.....

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