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Guillows Hellcat e-conversion experiment

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    #16
    Don't fret about how it feels on ground. The static thrust you felt is quite meaningless. More useful, you should calculate the rpm against the prop pitch.

    Choose a prop with a little higher pitch to keep the prop velocity up on the step. It is no use of having 1:1 thrust to weight ratio, when the prop velocity is near the stall speed of the model.

    Many years ago, many small electric warbirds are designed to use only direct drive speed 400 brushed motors, which produced very little power, compared to today's brushless motors. Using smaller diameter prop with respective pitch is the key to make them fly well.

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      #17
      Sorry, should've also provided some perspective on the size of this puppy. It's 12"/30cm in length. Wing span is 16". Here are some pics on it with my hand (not thaaat large, ok):

      For now, prop is as per the motor spec. 3700kv with suggested prop of 5x3.

      Will check on the rpm as soon as I find and recalibrate the tacho.

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        #18
        I think it is going to do just fine with that motor and prop. Just use a Lipo pack as small as you can find, as long as it can keep up with the current draw.

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          #19
          Latest updates from the weekend effort:
          - managed to resolve the issue of sustaining the rpm (smaller prop width for the 5x3 which was brand new GWS stock at Jethobby). Thanks to Moh, he helped figure the draw on the lipo with the prop was over the capacity
          - shaved a few more holes on the airframe where I could (firewall, ailerons, etc)
          - started covering the tissue (didn't do too well with the wing top having a gull like contour)
          - watered the tissue and the shrinking was immediate
          - tried spraying on the dope but the brush does the job better! (dope isn't meant to be sprayed on!... Dope101 for eager beaver spray painter)

          Tissue seems to be softer / more fragile that what I remembered on a glider I built before. So, looks like I will paint before the maiden after all! Next up, primer (Mr Surfacer 1000) and then get some plastic model paint to work the 2 tone WW2 Pacific air theater colors for the Hellcat (I'm sure I have all this crap in KL but duuh, where am I?).

          So, all advice incorporated so far. Have tried to lighten up the balsa / ply frame, prop size matched better, receiver cover is off (but still feels heavy).

          Not too far off from getting it all together for the maiden. Still have to re-do the wiring to remove the brass connectors, shorten the heavier wires, and test for the CG balance (apart from the asthethics, painting).

          Comment


            #20
            Hi Dave,

            Sim Lim Towers (top floor). Several shops there sells heat shrink insulation tubing in a whole variety of sizes and colours. A worthwhile investment.
            To win........one must not lose.

            Confucius

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              #21
              I have a heap of Doculam for your next project if you are interested. Very light heat shrink plastic, much stronger than tissue and paintable.
              To win........one must not lose.

              Confucius

              Comment


                #22
                Hi Tony,

                I'm a beginner balsa basher. Where can I get Doculam? I need to save money rather than spending 20 -30 bucks for a roll of Monokote.

                Can you sell me some?

                Regards, SS
                "Always fly with a responsible attitude. You may think that flying low over other people’s heads is proof of your piloting skill; others know better. The real expert does not need to prove himself in such childish ways..." - the Multiplex Build Manual

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                  #23
                  Originally posted by Tony View Post
                  I have a heap of Doculam for your next project if you are interested. Very light heat shrink plastic, much stronger than tissue and paintable.
                  hey, I have heard of this, just plain old heat laminate for documents. You just put it on the plane and iron on like those RC coverings, but tougher and great for paint jobs.

                  did you buy overseas or source locally?
                  Relax and Enjoy The Hobby.
                  Note to self: Must stop buying too much stuff.

                  Comment


                    #24
                    Originally posted by Sunstorm View Post
                    Hi Tony,

                    I'm a beginner balsa basher. Where can I get Doculam? I need to save money rather than spending 20 -30 bucks for a roll of Monokote.

                    Can you sell me some?

                    Regards, SS
                    Yup, I can most certainly sell some. I may have some 10+ packets left over from my electric days. Doculam is a material used for laminating documents. Some modeller probably discovered that it makes a great covering material for smaller aircraft. Its shrink characteristics is quite manageable and it is suprisingly tough considering its thinness and weight. But note that it comes in a kinda of semi opaque white but it clears to totally transparent when you heat/shrink it. The surface is paintable with acrylic paints etc but you will need to clean it thoroughly first and better still if you scour it with steel wool.
                    To win........one must not lose.

                    Confucius

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                      #25
                      Originally posted by Jack_Chen View Post
                      hey, I have heard of this, just plain old heat laminate for documents. You just put it on the plane and iron on like those RC coverings, but tougher and great for paint jobs.

                      did you buy overseas or source locally?

                      I bought in individual packets from a hobby shop in Australia. Oz? something, can't remember the name. I later managed to get some from a friend who bought an industrial sized roll. I think his Great Grand children will be using the stuff to cover their planes from the same roll - it was that big. ha ha.
                      To win........one must not lose.

                      Confucius

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                        #26
                        Rite... ze tissue & dope is already done. Will have to consider for the DH Mosquito mebbe. Haven't seen or felt this stuff so just a little weary about how this stacks up against monokote for weight. Another worry I have is the whole warping possibility with heat shrinking, etc. Not as drastic with tissue.

                        Will try to catch up with Tony to evaluate in the longer term for the DH Mosquito... (looks like a 2011 project!). Have to finish what I started first....

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                          #27
                          Ok, back to getting this on track and off my workbench.....

                          Didn't do much today but as of yesterday, had the dope settled in well. So, installed the elevator controls which is another poorly thought thru solution. Didn't spend too much time looking for mini clevises, etc so just z-bent the wires assuming the servos were trimmed (I'm sure it'll be fast fingers flying it!). Anyhow, secured the makeshift horn with epoxy and hope it doesn't mash up the balsa in the longer term. Tested movement today and it's satisfactory.

                          Can't seem to sort out the wrinkle in a section of the tissue on the starboard wing. Seem ok for the moment.

                          Still to-do is positioning the ailerons & glueing them in, the re-wiring, primer coat and base coat. If I get to my supplies in KL, will use the Future floor polish to seal in the paint. Also not looking forward to masking the canopy.

                          Then, it's a matter of installing the motor, and checking for CG while positioning the battery / Rx.

                          And the way work's looking, won't be able to close this thread off earlier than I'd hoped.

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                            #28
                            Work can sure put a 3 month delay in getting this moving. And even so, the momentum to get going again is tough. Anyhow, managed to start the prep for the primer. Even so, realized that my old Mr Color hobby paints from ages ago have dried up.

                            So, here's a simple pic on the masking for the canopy. Have also epoxied the firewall on so I can mount the cowl before the primer goes on. Taped up the wing servo but really doesn't matter to me.

                            Will try to get the primer and paint done soonest. Was testing the plastic model airbrush last night. Thread lock would be a good thing to buy now.

                            Was fortunate enough to be given an old 60 Curare. Thinking of swapping projects but this one is sooooo close to wrapping up. Will strip off the old monokote and work the same fiberglass real as my Joker build. Watch out for that thread.

                            Comment


                              #29
                              let me know if it works out....have a few in boxes yet to fix...

                              Comment


                                #30
                                Well, the secret will be in the weight of the components. The motor and battery is as good as it gets from JetHobby. I could do better with the servos and receiver. Always a function of cost - I think SHS has the West (I could be wrong on the name) servos which are well sized. And of late, I think I've read of smaller servos coming out. Look, if Parkzone can get it to work on the BNFs, these items exist. For now, it's whatever I can get my hands on at a decent price (and it's not cheap...I can appreciate why the BNFs or equivalents don't come under $120, and these are foamies!)

                                Also, there are loads of threads on RCUniverse and RCGroups on these conversions / miniturizations. I've seen some fly on YouTube but also, a lot of these are the large Guillows versions. My advice is just get building. I waited too long.

                                Anyhow, 4 more spray variants, decals and we should be ready for pre-flight. Have the neutral gray bottom, intermediate and navy blue top and Future Floor finish to seal.

                                Pictures are from the primer (I swear, could really do with more practice getting the pressure and viscosity right). Attached is the ideal color scheme from the USS Princeton but, not sure I'll get to the eyes and teeth just yet:

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