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CG for 1400mm T-28

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  • CG for 1400mm T-28

    Received this plane for Christmas with 2 3000mAh batteries. Appears to be tail heavy. How much weight has anyone being using? Would CG be better with 3600mAh?

  • #2
    Re: CG for 1400mm T-28

    I have only used the 3600 batteries in my 1400 T 28 and it cg'd perfect with no weight. You might try looking up the weights of the 3000 and 3600 and put the difference in by the battery and see if that works for you. Also I would CG it with the retracts up, that nose gear has a bit of weight. All planes can be a bit different it seems, have 2 of few models, and they all CG'd a bit different.

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    • #3
      Re: CG for 1400mm T-28

      Thanks for the info. I did have the gear retracted. I've read some that some have had issues with CG on FMS planes - I am using CG stated in building guide at 80-85 mm.

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      • #4
        Re: CG for 1400mm T-28

        I fly my 1400 T28 with either (1)3000 and (2) different 3300's and all three weigh different but makes little or no difference in CG or the way it fly's. I CG mine with the gear up between 80-85mm like the book says and haven't added any weight. I position the battery forward in the slot and it fly's awesome.
        Always better to be a little nose heavy than tail heavy. And position all electronics as far forward as possible.

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        • #5
          Re: CG for 1400mm T-28

          Some pilots are having complete success with the battery placement as is. I however have never been lucky with standard battery placement. It was very difficult to fly in any kind of wind or if flaps were down. At times it was very pitchy. This happened on V-1, V-2 and V-3. So your not alone. Using a 3000ma - 3300ma battery.

          Cut the front foam square in front of the battery pocket flush. Add velcro to the bottom of the battery bay. Place the battery forward, the hind end of the battery should line up with the velcro strap. Any battery you use 3000ma to 5000ma will sit in that position. Yes thats a 5000ma hard case battery in the plane. You'll find it will fly perfect. This works on V1-V3.
          Attached Files

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          • #6
            Re: CG for 1400mm T-28

            I also had a problem with my maiden flight with the T-28 1400 mm. The CG machine measured nose heavy at 85 mm with the 3600 battery, but the flight was difficult. The nose pitched very abruptly 45 degrees upward into an 8 mph headwind at 100 feet with the gear still down. It took full down elevator to correct and it was up-down after that. It flew as if tail heavy. The nose gear bay was open the whole time. I have not flown since.
            I could not figure this out until I see Capt. Mike's solution.
            Do you think another possible explanation for the abruptly upward pitch with the nose gear bay open could be the parachute effect of the nose gear bay, which is pretty large? The problem did seem to be worse into the wind. That was my only diagnosis other than tail heavy (which I thought was nose heavy).
            I would like your thought on the parachute bay idea.
            Thanks

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            • #7
              Re: CG for 1400mm T-28

              I fly mine with a Zippy compact 4500 and have no problem with the CG.

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              • #8
                Re: CG for 1400mm T-28

                That is exactly what my Trojans did. That is a CG problem. You can fly with the landing gear down at full throttle straight and level if the CG is correct. The gear bay open has no impact on flight character. Set your elevator even and flush, cut the battery bay move the battery up front. It will be the best flyer. Trojan is the easiest plane to fly when set up correctly. I have over 100 hours on trojan, not 100 minutes, hours.
                I had to do the same on the Trojan V3 also. The picture of the plane is the V3 that we used in the Motion video with this setup. I logged just over 15hrs so far on this plane.

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                • #9
                  Re: CG for 1400mm T-28

                  Thanks, Capt. Mike.
                  It makes sense now. The CG site (80-85 mm from the leading edge of the wing) recommended by FMS must be wrong.
                  I have seen in other threads that FMS recommended CG sites have been questionably "tail heavy". Has this been your experience? And if so, in which planes have you noticed this?
                  What do you do to determine your CG measuring point if you cannot go by the manual?

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                  • #10
                    Re: CG for 1400mm T-28

                    On early birds by FMS yes CG is questionable, I always set the CG to spec and go from there. I found I had to move cg every now and again. One thing about FMS their CG is some what forgiving they do make balanced planes and going by manufacture specs is a great place to start. Just adjust according to flight character.

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                    • #11
                      Re: CG for 1400mm T-28

                      I'll give this ago - sounds like a fix!!! Thanks. I still haven't flown - any suggestions on low & high rate throws??

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                      • #12
                        Re: CG for 1400mm T-28

                        What radio do you use?. Spectrum go high rate 100% stock. On low rate, 80% movement on the servo and 20% expo. Tactic I would go stock for high rate and low rate 80% servo movement with 30% expo.

                        If you have a 3 position switch lower rate of 75% and 25% expo. Be careful to low on servo movement you'll lose the effectiveness of the elevator. Trojan is well behaved when set up right. If you have a different radio let me know.

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                        • #13
                          Re: CG for 1400mm T-28

                          I use a Spektrum DX7. Have thought about upgrading to new DX9.

                          Comment


                          • #14
                            Re: CG for 1400mm T-28

                            Capt. Mike,
                            Do you mix in some down elevator with your flaps on the T-28 1400 mm? If so, how much.

                            Comment


                            • #15
                              Re: CG for 1400mm T-28

                              I never use mix. I like being in control of each surface. Flaps allow the plane to descend with its nose down without gaining speed. In an advent of a go around it requires lots of up elevator to compensate for mix. In slow flight I want a high angle of attack applying back pressure, using flaps for extra lift, using throttle to compensate for drag, at this point its not a great idea to have down elevator mixed in my deployed flaps. I've seen all kinds of weird mixes pilots have programed in their radios but for Trojan it doesn't require it. You want to know the secret to landings with Trojan?
                              On approach come in straight and level in slow flight and control the "descent rate", the closer to the ground the slower the descent rate get 6'' to 8'' above ground level, cut throttle and maintain that altitude as long as possible and swooooooosh grease right in. Check out our landings on motionrc and a old video made back in the early days. Trojan is a great flyer you don't have to be afraid of it but you do have to respect him.
                              http://www.youtube.com/watch?v=GffDeDdaGKo https://www.youtube.com/watch?v=7_ZH_l7yzUs

                              Comment


                              • #16
                                Re: CG for 1400mm T-28

                                in your version 2 t-28 where in the battery bay is your battery if u could post a video of it it would be greatl appreaciated. how far up from back is it ? when using your 3600mah battery

                                Comment


                                • #17
                                  Re: CG for 1400mm T-28

                                  I have a picture of battery placement a few posts back. Just line up the back of the battery with the velcro tie down. This is the exact balance point so no matter the battery size its right in that spot.

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                                  • #18
                                    Re: CG for 1400mm T-28

                                    Capt. Mike,
                                    You are right on the CG. With the 3600 battery far forward (after removing the little foam wall in the front of the battery cavity), she flew like a dream. Rock solid and guys at the field loved it with the fly by. Floated in on half flaps and 0 throttle, and landed on butterfly feet.
                                    I am now skittish on the manual CG recommendations for my FMS Piper J3 1410 mm before the maiden. Any recommendations on the FMS Piper and the RockHobby Waco? I asked this on another recent thread and no replies yet.
                                    Thanks

                                    Comment


                                    • #19
                                      Re: CG for 1400mm T-28

                                      Hi Bill,

                                      I have been flying my FMS 1410 J3 for a couple of months now, and CG has not been a problem at all. I did add about 0.5oz of weight to the nose, and am using a standard 2200mAH 3 cell battery and she flies great. About the only thing to watch for is ground handling on take off. Make sure you are ready with a touch of right rudder on the take off roll. I practiced a bit of ground handling as much as I could on our grass field, and once I got the hang of it, take offs were nice and straight. Enjoy the J3, it is a delight to fly, and looks great in the air.

                                      Comment


                                      • #20
                                        Re: CG for 1400mm T-28

                                        On the Piper I just throw the battery in and go. I never worried about the cg. On Waco I put in the battery all the way forward then move it back about 1/4 inch or so. They both are really forgiving on CG.

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