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LX 64mm SR-71 Blackbird on 4S 12-Blade Power Setup

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  • #41
    Aros, WOW those pictures of the plane in flight are fantastic!!! they look real,
    So I was able to cut some of the battery tray away to accommodate my batteries,
    This plane is very light for its size, I was comparing it to the weight of my freewing F-18 and F-22 and they are within 50g at flying weight. Both those planes have 64mm 3300kv 12 blade motors.
    and while adequate, they are kind of on the slow side, I am not sure of the Kv in the SR-71(they are unmarked) but I was taxiing around and the plane does seem quite peppy. So if the plane is the
    same weight as my freewing planes but with twin motors, I suspect it will be much quicker than either of the F-18 and F-22.
    I replaced the goofy plastic wheels as it acted as if the plane was on ice, it wouldn't grab when turning slow and just kept going straight. the servo was turning but it was skidding
    Waiting for calmer wind before maiden ,planning on this weekend!

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    • #42
      Thanks! A pro photographer buddy of mine took them...Here's some more...Good luck on your maiden!

      My YouTube RC videos:
      https://www.youtube.com/channel/UCDZ..._bdGEJBmtV7YUw

      Comment


      • #43
        https://www.youtube.com/watch?v=HUAO3zT5ImI&t=65s Here is the maiden of the SR-71,, if that link doesnt work just go to youtube, and look up flyjets305 you can see the video there
        It takes off just like the real plane, just a slow climb out, it is very cool, the power is "adequate" we know its not a speedster, but thats not why i bought the plane. I was using a gyro, so the flight
        was pretty smooth, I started with 60/40 ailerons, 70/30 elevator, because i didnt know if was going to be squirrelly, I reduced the rates to 70/30 and 80/20 after the second flight.
        I didnt realize this plane was so light, it weights the same as my Freewing 64mm F-22 and F-18, but with 2-64mm motors at the same weight I thought it might be a little faster.
        The only negative i really have is that with 4s2000mah 50C battery my first fllight was only 2 minutes and the batteries were at 3.69v the second flight was 1:40 and the batteries were at
        3.77v so i dont know if i can put a 2500-3000mah battery in there, I would keep it at 4s, I was the only one at the airfield so its filmed on my iphone headmount but you get the idea.
        let me know what you think

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        • #44
          flyjets305 Brilliant! An excellent flight for a maiden of this bird, well done!

          The gyro definitely helps and you seem to have a good setting for throws that works for you. Landing was great! Impressive for this being your maiden. Yeah, you will need a larger mAh battery. I think I averaged 3500-4000's in mine. You have to carve out the battery bay but you have no choice unless you like 2 minute flights or less, which obviously you don't.

          Bravo, Zulu!
          My YouTube RC videos:
          https://www.youtube.com/channel/UCDZ..._bdGEJBmtV7YUw

          Comment


          • #45
            Thanks Aros, just to be clear, you said you used 3500-4000 ,(but not with the stock motors?) was that 4s ? did you ever takeoff from runway? or always hand launch? and getting back to the batteries, increasing the size
            of the a 4s above 2200mah, of course, will add weight, and there is only one way to place it which is the extra length would be towards the Rx, as the front nose gear limits how far the battery can be placed forward, with that in mind did you have to calculate a different CG and also , you mentioned you had different motors installed in yours. I'm thinking first, just adding 4s2600-3000 which will only add about 50g and use the stock motors, i just like to get close to 3 min flight would be nice

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            • #46
              @Jpahemi1 HI John, are you back in town yet? did you see my maiden video? I flew it with 4s2200 and only got between 1;30-2;00minutes of ecstatic fun LOL . way too short.
              I remember you mentioned you were going to use 4s 3600mah, i was thinking about maybe going to use 4s 2600-3000 which would only add about 50grams of weight, and hopefully wont
              effect performance but give at least another 30-60 seconds of fun flying. let me know

              Comment


              • #47
                Yes my later models were 4S with the stock gear removed. The best setup was Don's Wicked but unfortunately it's been too many years so I can't recall the specs. Flew like a Blackbird should! Super fast, I loved it!
                My YouTube RC videos:
                https://www.youtube.com/channel/UCDZ..._bdGEJBmtV7YUw

                Comment


                • #48
                  I have change sun 64mm units installed in mine and use a 4s 5000 pack to fly her. It’s been a minuet since my last flight but she was fast enough and flew long enough for my liking, she’s just to damn fragile.
                  I did mod my battery compartment and also added the whale tail.

                  I looked for videos of my SR-71 but only found the one I did with a pusher prop. That ended up becoming combat material and after about 10 sections finally found it’s demise.

                  Gravy

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                  • #49
                    Here's an old video I found of one of my flights with Don's Wicked power system...

                    My YouTube RC videos:
                    https://www.youtube.com/channel/UCDZ..._bdGEJBmtV7YUw

                    Comment


                    • #50
                      Flyjets
                      that was a great flight. Your far ahead of me. Our field doesn’t open till the middle of the month. I’m still working on mine. I finished the thrust tubes and I’m just starting on the whale tail. I’m probably over thinking this build. I’m slow at building anything but your success may inspire me. Did you do any mods to yours at all.
                      John

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                      • #51
                        1. Aros, another nice video, that launch looked so easy it just flew out of his hand. You should really consider getting another one-lucky #14 right? lol
                        2.@Gravy and Aros, your main mods was just to change out the edf with better 64mm edfs? I know you removed the landing gear but how does the CG work with much larger batteries?
                        I am going to fly mine some more to get use to it with the stock set up and 4s2200, first I will try a slightly larger battery , then I will consider swapping to FMS 3150kv that I have in my F-15
                        that motor is really fast. and add slightly larger battery, I cant image anything bigger than maybe a 4s3000mah but we will see.
                        3.@John,thankyou, I hope to have better video soon, I have not done any mods yet, it is completely stock, using the 4s2200mah, Oh, I did cut about 1/2" of foam from the battery bay, so it the
                        battery would fit in easier, If I do go to larger battery, I guess I will have to cut a little more foam out, lol but the only other thing I may do is swap out the motors for the fms 11 blade 64mm and see how that flies.
                        good luck with yours, and I will be watching

                        Comment


                        • #52
                          Flyjets
                          Quick question, did you glue the fans in place or just use the hatch cover to hold them in place. Seems like the the best way so they can be serviced easier.

                          i calculated the fan sweep area for the Freewing 64 mm 12 blade fan. 90 percent of the FSA gives me a tailpipe diameter of 54 mm.

                          I didn’t like having the tailpipes not overlapping the fan housing. I tried several times but if the pipe fit snug all the way around at the aft end of the fan hatch, I couldn’t slide it over the fan housing.

                          My solution was to design the pipe so it fit tight at the aft end of the hatch and had the 54mm exit diameter. I then made support rings from 1/8 lite ply and glued them into the fuse with BVM Aeropoxy.

                          The thrust tubes fit great and are sealed to the fuse so there should be no issues with air getting past the tubes on the outside causing a collapse. We will see.

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                          • #53

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                            • #54
                              One more thing each tube and lite ply ring weigh 1/4 of an ounce. The tube is made from .010 Mylar

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                              • #55
                                flyjets305, Lucky #14 indeed! lol....As for CG I just placed the battery fore or aft until I reached the recommended CG point. I carved the hell out of the battery bay area so I had plenty of room for whatever battery I chose. I also had thrust tubes in mine which is a Must Mod IMO. Speaking of, really nice work there Jpahemi1!
                                My YouTube RC videos:
                                https://www.youtube.com/channel/UCDZ..._bdGEJBmtV7YUw

                                Comment


                                • #56

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                                  • #57
                                    Note I cut the battery box back to the next panel line. So that’s about 1/2” of foam removed here is I’m using an Admiral 4s 3600 pack. Fits good let’s see if it CG’s there

                                    Comment


                                    • #58
                                      Jpahemi1 the motors in my plane seemed to be glued in place, remember my came stock, but since they dont have screws holding them down, I think just a dab of ca glue just keep them in place,would be sufficient and easily pried up if needed for service, i think the hatch covers alone would probably do the job,as they are pretty snug.
                                      Regarding the thrust tubes--that is above and beyond my pay grade, I leave that up to my aeronautical engineers on staff--lol , but i do question the use of tubes in this particular model , since it appears to me that the entire motor shroud in itself acts like a thrust tube..
                                      I'm still waiting for my 11blade motors to arrive, but in the meantime I have ordered a 4s 2600mah battery to try, I believe in incremental baby steps, so i will try the 2600, then go to 3000, if it can
                                      successfully increase my flight time, then I will install the motors when they arrive, and eventually try a 4s3300, but i think that will be MY limit for weight.
                                      Nice pictures of your project, It looks pretty nice with no decals.

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                                      • #59
                                        So I took some pics of mine this morning. In the pics you can see the right aileron inboard hinge is stoking up. I need to regule it back into place. My 4s 5000 pack fits nice and tight with Velcro strap holding in.

                                        Gravy
                                        Attached Files

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                                        • #60
                                          Look at you Gravythe clown rockin the tail rudder mod! Nice. Your simple battery tray extension and velcro is much cleaner than my jobs...I would just hack, paint and stick a battery in with Gorilla Tape, lol! The hinges/rods/horns were always needing attention. Very delicate, I constantly was regluing them. Definitely something to always look at during any pre flight checks.

                                          I'm no engineer but this mold BEGS for thrust tubes due to the wide expanse trailing edge of the exhaust ports That's a ton of space for thrust output to disburse. Whenever I would fly without them versus with the difference in performance was striking. I sure wish Freewing would tackle this bird. She deserves to have a spot in the New Gen Era of EDFs.
                                          My YouTube RC videos:
                                          https://www.youtube.com/channel/UCDZ..._bdGEJBmtV7YUw

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