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FMS 800mm warbirds-why are they so different?

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  • FMS 800mm warbirds-why are they so different?

    Hello, I wanted to ask the forum and the Motion RC guys a question regarding the 800mm warbird series. I have watched all the MRC videos on these, and noticed that Mike has commented several times that these are challenging planes to fly. (see P-51 Mustang Petie 2nd video.) I have also noticed that of all the planes I fly, these 800mm planes are the most difficult to do a ROG takeoff. Even hand launching often results in a quick torque roll to the left and into the ground. Once in the air, and with CG correct, they are a delight to fly. (Despite the issues I have with these, I love the detail and size of these planes. Perfect for fitting in my car without taking wings off.)

    My question is, what is it about these that makes them more difficult? I have flown most all of the Parkzone UMs with no problems at all, and the new Flyzone Aircore planes are a delight to fly and not nearly so temperamental. My larger planes, 1100mm and up don't exhibit this characteristic either. Don't get me wrong, I really like this series, I have 5 of them now, but I wanted to see what you guys thought. Maybe I need to add more right aileron on take off runs than usual? Has anyone else run into this? I have only been flying for less than 2 years, and am completely self taught using Realflight simulator. One thing I have noticed about the simulators is that they don't replicate take off runs or stalls all that well. Guess that is just one thing you have to pick up from really flying the models.

    Also, which one of this series is considered to be the most docile on take offs and general flying? The Skyraider is the one I seem to have "tamed" and love flying it. I went to a 2 blade prop (8x6), and about a 25mm CG from the leading edge of the wing, and now it flies great. Is there something about a 3 or 4 blade prop that causes more torque roll on takeoff?

    Sorry for all the questions, but just trying to learn from those who have more experience!

  • #2
    Re: FMS 800mm warbirds-why are they so different?

    I'd love to dig into this with you. This evening I'll give you my opinion on this. Currently I'm away from my desk.

    Ryan

    Comment


    • #3
      Re: FMS 800mm warbirds-why are they so different?

      You are right about the sims and that you may want a little more right aileron trim on take off. So many forget that there's more than yaw to counteract on takeoff. There is also roll and even pitch to take into account. The 800mm birds have a tight margin especially for TO and landing. I attribute some of this to their size and lack of mass. For instance when you let's say bounce a bigger bird on landing you may stall it but you may not. When you bounce a smaller bird you either fly away and try again or helplessly watch it bounce to a stop. Seems like once their attitude has been changed they take over the controls. Part of this again is there so light that the tail drops rather quickly, rather than planing and staying up off the deck until you bleed off speed or input back pressure. The bigger plane has enough energy to maintain controlled flight due to its forward moving momentum. This energy is maintained largely impart due to its mass and inertia allowing it to keep its forward momentum. Adversely the smaller planes lose airspeed very quickly causing them to be a handful. From my experience i feel like the 800mm planes really require you to be on your game and fly them down, almost maintaining what seems like an undue amount of throttle. This is funny because their size alone almost suggests that they would be good for new flyers. This is a bit of a misnomer as we feel it takes a bit of experience to fly them well. I always flew these with the recommended 2 cell batts 1000 and 1300mah. Many guys swear by the 3s 1100 and 1300 packs. I think the extra weight probably doesn't hurt one bit.
      Let me know if that helps.
      Ryan

      Comment


      • #4
        Re: FMS 800mm warbirds-why are they so different?

        I have learned to do a longer take off roll to counter the torque roll effect, then there is air moving over the surfaces and it doesn't take much to counter it.

        They are more touchy than the PKZ models due to the scale like surfaces. The PKZ UMs use a flat foam formed wing, not airfoiled. This gives them more of a airfoil profile of an airplane with slats and partially deployed flaps, making them a touch more stable. I love the more scale like looks of the FMS birds. The aerodynamic problems arise from the fact air doesn't get smaller. I have the FMS T 28 in 800mm, the Durafly in 1100mm and the FMS in 1400. The 1400 version is the easiest to fly, more weight and the air can interact better with the surfaces. I don't know the exact power to weight ratios of the 3 planes, but would guess them to be fairly close due to the close way they preform. Going to try putting a stabilization system in the 800 one, see if it tames it down a bit.

        Don't know if the extra blades cause more torque on takeoff, they might a bit. The worse plane I own for torque on takeoff is my PKZ Stinson SR 10 and it only has a 2 bladed prop. I have played around with changing props. If the normal rule of thumb is followed ie: say you run a 10-6 two bladed prop and want to go to a 3 bladed version, to keep amps close you use a 9-6 three blade the amps were close and the torque on take off seemed very close to the same. It all boiled down to using a longer roll on take off to get the speed up to counter it. I do hand launch the 800mm Corsiar though, it seems to help not having the gear for drag, I just don't give it much more than half throttle. I played around with bringing it almost to a stall, then adjusting throttle to see how low I could get away with and still climb out. I didn't completely stall it due to it would be getting some airspeed by hand launching. I have done this with other aircraft to get an idea of how much throttle I need to hand launch. Which altitude and air temp make a big difference, so it is basically just a base line.

        Comment


        • #5
          Re: FMS 800mm warbirds-why are they so different?

          Ryan and Crosswind 92-Thanks so much for the reply and pointers. That makes a lot of sense about the airfoil differences between the PKZ UMX models and the real airfoil used by the FMS series. I hadn't thought about a flat foam formed wing operating like it was a higher lift wing. I was surprised to hear you say that the PKZ Stinson was bad to torque roll though. I have that plane and it is one of my favorite fliers, and only saw it try to exhibit a torque roll once, and I thought that was because I tried to take off the grass too quickly. Like you said, a longer take off roll really does help out with reducing torque rolls.

          I am in the process of "tuning" my Zero to get it to fly as well my Skyraider, and have put an 8x6 2 blade prop on it and moved more weight into the nose. Once I get that one going, I have a P-40 and a T-28 to play with! I am thinking seriously about one of the Mustangs too! This stuff is very addictive!

          Is there one in this series that is easier to start off with, assuming you have experience with other aileron, low wing warbirds in larger scales? I would have guessed the T-28, but after talking with Ryan and reading about the P51 models, maybe it would be more stable? I'd like to get one of these flying without lots of "battle scars" resulting from fixing crashes!

          Thanks again to both of you for the inputs!

          Comment


          • #6
            Re: FMS 800mm warbirds-why are they so different?

            i love the 800mm T-28's.

            my current setup with ALL my T-28's is. i use the FMS 1700KV motor with a 30a esc with a 3S 1300mah battery. an APC 7 X 5 prop with the e-flite 3mm prop adapter (have to cut down the motor shaft)

            this setup will make the T-28 ALOT faster than stock. but you can fly it slower with less throttle.
            i hand launch all my T-28's..no torque surprises at all.....just straight ahead at a little over half throttle

            i like the lttle extra weight of the 3S battery up front

            this is just my experience with the 800mm T-28. and i love it

            Comment


            • #7
              Re: FMS 800mm warbirds-why are they so different?

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              ------=_Part_72784887_827343061.1392432636458

              Thanks for the update on the T-28. I have not tried any 3cell combinations =
              with my 800mm planes, but the extra weight probably does help. I have my gr=
              ay T-28 ready to fly now, and waiting for decent weather here before I try =
              the maiden flight. Thanks too for the half throttle recommendation on hand =
              launching. That might have been part of my problem before as I was trying t=
              o hand launch at about 3/4 throttle and encountering torque roll with the Z=
              ero.=20

              ----- Original Message -----

              From: "brick47 [via Motion RC Community Forum]" <ml-node+s1075610n1706h61@n=
              5.nabble.com>=20
              To: "Loneflier" <rich121@knology.net>=20
              Sent: Wednesday, February 12, 2014 11:15:24 PM=20
              Subject: Re: FMS 800mm warbirds-why are they so different?=20

              i love the 800mm T-28's. =C2=A0=20

              my current setup with ALL my T-28's is. =C2=A0i use the FMS 1700KV motor wi=
              th a 30a esc with a 3S 1300mah battery. =C2=A0an APC 7 X 5 prop with the e-=
              flite 3mm prop adapter (have to cut down the motor shaft)=20

              this setup will make the T-28 ALOT faster than stock. but you can fly it sl=
              ower with less throttle.=20
              i hand launch all my T-28's..no torque surprises at all.....just straight a=
              head at a little over half throttle=20

              i like the lttle extra weight of the 3S battery up front=20

              this is just my experience with the 800mm T-28. and i love it=20







              If you reply to this email, your message will be added to the discussion be=
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              div style=3D'font-family: times new roman,new york,times,serif; font-size: =
              12pt; color: #000000'>Thanks for the update on the T-28. I have not tried a=
              ny 3cell combinations with my 800mm planes, but the extra weight probably d=
              oes help. I have my gray T-28 ready to fly now, and waiting for decent weat=
              her here before I try the maiden flight. Thanks too for the half throttle r=
              ecommendation on hand launching. That might have been part of my problem be=
              fore as I was trying to hand launch at about 3/4 throttle and encountering =
              torque roll with the Zero. <BR><BR>
              <HR id=3Dzwchr>

              <DIV style=3D"FONT-SIZE: 12pt; TEXT-DECORATION: none; FONT-FAMILY: Helvetic=
              a,Arial,sans-serif; FONT-WEIGHT: normal; COLOR: #000; FONT-STYLE: normal"><=
              B>From: </B>"brick47 [via Motion RC Community Forum]" &lt;ml-node+s1075610n=
              1706h61@n5.nabble.com&gt;<BR>To: "Loneflier" &lt;rich121@knology.net=
              &gt;<BR>Sent: Wednesday, February 12, 2014 11:15:24 PM<BR>Subject=
              :
              Re: FMS 800mm warbirds-why are they so different?<BR><BR>i love the 8=
              00mm T-28's. &nbsp; <BR><BR>my current setup with ALL my T-28's is. &nbsp;i=
              use the FMS 1700KV motor with a 30a esc with a 3S 1300mah battery. &nbsp;a=
              n APC 7 X 5 prop with the e-flite 3mm prop adapter (have to cut down the mo=
              tor shaft) <BR><BR>this setup will make the T-28 ALOT faster than stock. bu=
              t you can fly it slower with less throttle. <BR>i hand launch all my T-28's=
              ..no torque surprises at all.....just straight ahead at a little over half =
              throttle <BR><BR>i like the lttle extra weight of the 3S battery up front <=
              BR><BR>this is just my experience with the 800mm T-28. and i love it <BR><B=
              R><BR><BR><BR>
              <HR SIZE=3D1 noShade>

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              • #8
                Re: FMS 800mm warbirds-why are they so different?

                I am just ordering my first 800mm warbirds so giving my input based on in general. I recently did some testing with 1100mm class of FMS and Durafly warbirds and noticed that they all had dramatic left turning tendencies. The easiest way to put it was the motor and prop were lifting off before the wings are fully ready to take off. Longer runway use has since solved that on my corsair and p-51.

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