340 VII performance

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  • #94000

    Any way to get a 340 to do 220-230KTAS?

    Can you add AA intercoolers to a ram VII? What was the fastest 340?

    #165505
    rhill
    Participant

      quick answer…..No. But possibly if you take it to 25K and run the guts out of the engines it’s possible. Real numbers from my experience in a 340A was 205 KTS TAS with AA intercoolers on -NB engines in mid to high teens running 32/2300. I’m sure others will chime in with faster speeds, but if you expect much more than that consistently you’re going to be disappointed.

      #165506
      pmcnamee
      Participant

        The C-340’s are a very aerodynamic challenged airplane. Just like a Beech Duke, looks great on the ground. Too much Drag added to make the airplane stable.

        Keep’em Flying

        Pat

        #165507
        adancy1
        Participant

          I believe the RAM VII intercooler and the AA intercooler are similar in performance, and there would be no advantage to changing a RAM VII to AA.

          #165511
          rhill
          Participant

            An Aerostar is the only piston twin that will get consistent 230 KTS TAS

            #165518
            pmcnamee
            Participant

              I get 235KTAS at 44 gal./Hr. in the Stock (No Mod’s) C-421C. I have removed all the draggy worthless Deice Equipment to get it. It Helps to get the CG to the aft limit also.

              Fly Safe Fly Often

              Pat

              #165521
              rhill
              Participant

                WOW…never flew a 421 without boots. I never would have never thought those worthless boots were a 20 knot penalty 😯 . Good for you.

                #165532
                rpinkowski1
                Participant

                  On an ISA standard or cooler I will routinely see 220KTAS @ FL200 @ 65% power on my RAM VI C340A w/ AA intercoolers. ISA +15 and this drops to ~215KTAS @ FL200 which is where KTAS peaks. I do not think there are any conditions under which I could see 230 KTAS.

                  #165533
                  rstevens1
                  Participant

                    Pat,

                    I respect your oft-expressed minimalist, “clean design” convictions, as well as your vast experience in twin Cessnas, but must disagree with calling de-ice equipment on a 421C “worthless”.

                    True that you should focus on exiting icing conditions ASAP instead of relying on de-ice equipment to continue on. (Using the term “de-ice” here to include anti-ice as well. Also presuming that you’re referring just to pneumatic boots, and not electrically heated props, windshield, pitot tube, stall warning vane, and static ports as well.)

                    However, more than a few times I have been very glad to have the boots. Flying enroute in the clear above a deck, then picking up over an inch on the approach, I shed the ice with the boots after the MAP, allowing a normal approach speed instead of the +15 knots advised by the AD-mandated placard. If the runway is contaminated and not of air carrier length, that’s a big deal. Even then, I have been surprised by the effect of the residual ice entering the flare. Well above the “normal” stall speed, the plane quit flying, and “right now!” upon power reduction.

                    I guess it depends on the type of mission you fly, and the weather you might encounter to properly assess the tradeoff between always getting a few knots less in cruise, and occasionally sliding off the runway. At best!! Quite a few accidents on short final for an iced-up plane that made it that far before the fatal stall/spin. For myself, I would never consider removing the boots on a twin Cessna.

                    Keep ’em flying!

                    Ron
                    425, formerly T310R and 421C

                    #166477
                    dlawlor1
                    Participant
                      quote TOdaniel post_id=84763 time=1685655648 user_id=5713:

                      Any way to get a 340 to do 220-230KTAS?

                      Can you add AA intercoolers to a ram VII? What was the fastest 340?

                      Yup. RAM VI, AA, Scimitar.

                      #189394
                      jwester
                      Participant

                        I flay a 340 with Ram VII, scimitar props. Burning 17gph per side and using RAM’s settings for that ff I see 205ktas at FL 200-220. Sometimes a little better. Consistently being over 210-215KTAS without pushing the engines is hard for me to imagine. Maybe if you were lightly loaded and don’t mind burning some extra fuel.

                        #189405
                        ddefelice1
                        Participant

                          Take it to 25,000, firewall all six engine control sticks, then point it at the ground. 230 kts – piece-a-cake. LOL

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