Let’s Talk VGs

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  • #85203

    The 310 I fly has VGs on it. About 90% of my flying time in 310s is in this plane, so I really don’t have much experience without them. I’ve tended to say I need them for my flying out of short runways (2800 ft home base), but I also fly long days and am all about doing what I can to shave 10 minutes here and there. A few knots adds up over 10 hours. Less time in the air means I’m in bed sooner.

    So with that, I’m wondering about removing the VGs. We’ll ignore the gross weight change since that doesn’t really matter for me. My questions are:

    1) How much of a cruise speed difference have people noticed with VGs vs without?
    2) What sort of differences have been noted in low speed handling?

    Mark, I forget if your 310P has VGs? I didn’t notice a difference when I flew it into my home field.

    Thanks for entertaining my thought experiment.

    #106077
    jgrimes
    Participant

      I don’t recall any speed reduction when we installed our VGs. There was a noticeable reduction in stall speed though, down to 70-75 mph.

      Joe

      #106079

      Hi Ted,

      I don’t know… This sounds sort of like a “whacky” thing to do from my perspective. You’ve finally tempted me into posting again.

      The VGs buy you a “huge” additional safety margin if you get slow, especially if you’re low or single engined. I don’t think I would trade that for an extra 10 minutes of sleep, even if you could PROVE that you’d get a few knots out of their removal. I fly the twin for safety reasons. The same reasons it’s FIKI and dual pitot-static and all sorts of things that if I got rid of it’d fly a teensy weensy bit faster.

      I can tell you for sure that you can fly two or three knots slower by having your plane trimmed wrong (a little too much rudder one way and too much aileron the other). I would look into rigging my plane and getting rid of parasite drag by putting on new cleaner antennas and smoothing out the airframe before I’d get rid of my VGs. But, that’s just me.

      Oh, and I operate (at SL and standard day) from 2,000 foot paved and 2,300 foot grass strips in my 310R… So I really love the VGs.

      Cheers,

      Doug

      #106081
      quote JGRIMES:

      I don’t recall any speed reduction when we installed our VGs. There was a noticeable reduction in stall speed though, down to 70-75 mph.

      Joe

      Thanks, Joe. The sort of info I’m looking for.

      #106082
      quote DOUG:

      I don’t know… This sounds sort of like a “whacky” thing to do from my perspective. You’ve finally tempted me into posting again.

      Well, a number of my ideas are whacky. Glad to have given you motivation to post. 🙂

      quote :

      The VGs buy you a “huge” additional safety margin if you get slow, especially if you’re low or single engined. I don’t think I would trade that for an extra 10 minutes of sleep, even if you could PROVE that you’d get a few knots out of their removal. I fly the twin for safety reasons. The same reasons it’s FIKI and dual pitot-static and all sorts of things that if I got rid of it’d fly a teensy weensy bit faster.

      Obviously with everything it’s a trade-off. The de-ice costs me a few knots without a doubt, but that’s not going away because I fly in icing and need it. The point of the question was to ask what speed differences people have noted when adding them, speed (cruise) and handling (low speed). The 310N I fly has always had VGs under my ownership, so I don’t have that comparison. When I flew a ’55 310 (no VGs) I didn’t notice it seeming any more different at low speeds, and that included when I had to cage one and land OEI.

      quote :

      I can tell you for sure that you can fly two or three knots slower by having your plane trimmed wrong (a little too much rudder one way and too much aileron the other). I would look into rigging my plane and getting rid of parasite drag by putting on new cleaner antennas and smoothing out the airframe before I’d get rid of my VGs. But, that’s just me.

      I’m attacking the plane bit by bit to reduce drag. We just adjusted the rigging a bit and gained about 3 MPH. I’m happy about that! I’ve also looked at antennas (they’re about as good as they can be) and replacement of my tail beacon and belly strobe (some potential improvement there). There are other areas I’m looking into as well. What prompted this was I did remember seeing someone on here post that on a 421C (with winglets) they removed VGs and speed did go up a few knots. So, interested in what 310 owners post.

      quote :

      Oh, and I operate (at SL and standard day) from 2,000 foot paved and 2,300 foot grass strips in my 310R… So I really love the VGs.

      Yep, I’ve gotten out of a 1900×25 strip at SL and ISA+15F as well and base at a 2800 ft strip. I also know that on certain departures, I definitely have a period where my safety level is effectively a single with the power divided into two propellers. But it’s a small period, so I consider the risk to be acceptable relative to the overall flight.

      #106086

      Ted,

      Do you have VG’s on your rudder? If so, those would be keepers for me.

      Jim

      #106088

      Jim,

      Yep, VGs are on wings and rudder as part of the STC.

      #107207

      Ted…

      One thing to remember if you decided to remove the vortex generators… They were installed as a complete system (wings, vertical stabilizer, maybe strakes outboard of the nacelles) in accordance with an STC. As a major alteration, the alteration was recorded on an FAA 337 as well as a log book entry for the actual maintenance. You can certainly remove the complete installation and take the airplane back to its original configuration, but you’d need to remove all parts, pieces and components of the installation, as well as the Flight Manual Supplement.

      Because it was a major alteration to install the STC components, it is also a major alteration to remove the components and return the airplane to its original configuration. That will require another FAA Form 337 and it will need to be signed by an A&P and approved for return to service by a mechanic with Inspection Authorization.

      Like any other aircraft certification process, it’s not over until the paperwork is done.

      Just my thoughts.

      Brian Ingraham

      #107216

      The majority of my twin Cessna time is in airplanes without VG’s on them. My 310 came with them. I’ve brokered two 310’s in the past 2 years – both Q’s – with them recently as well as trained their new owners. I saw no noticeable loss in cruise performance from non-VG Q’s.

      My 310 also shows no loss in cruise numbers from a nearly identical 310 I owned years ago without them. But on the low end of the speed spectrum, they are great. Although published Vmc is 5 MPH lower, I stick with the same original factory speeds and use the VG’s as a buffer. They are a must. I’d never consider removing them.

      Guy

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