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Testing speed brakes on the 260se

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  • kwmoore
    replied
    An approach of this sort is obviously a pretty
    steep approach and one that I normally would not use
    very often. It would, however, provide some real
    benefits in that with an engine failure during the
    approach, there is no doubt that you can safely reach the
    runway, obstacles do not concern you, and a shorter
    landing roll is generally possible with a steeper
    approach to touchdown (as opposed to dragging it in). In
    addition, they would be great at hitting a spot during an
    emergency landing. They are not vacuum powered, but
    rather electrical, so an engine failure will not affect
    their performance. It would be simple to set up a
    high approach, then hit the spot through the use of
    the speed brakes. As I said earlier, I did shoot some
    really steep approaches and found they worked
    exceptionally well. An approach over an 800' obstacle is a
    rather serious affair, but the speed brakes handled it
    well. The only problem with this is the timing of the
    flare, as the rate of descent is very high during the
    final stages of the approach. I did not do this enough
    to become really sharp at it, so I was rather
    conservative in my technique. I would always brake the descent
    at about 100' by retracting the speed brakes and
    continuing the approach in a normal fashion. When you lose
    this much altitude this quickly, the ground is really
    coming up at you fast. It was not as quick as the old
    airshow days, but it was fast enough to get my attention.
    Once again, with sufficient practice, I think a person
    could get really good at this by braking the rate of
    descent virtually at the flare. The speed brakes are
    installed in the upper wing just outboard of the fuel tank
    area. They might be compatible with the Wren, but a
    careful analysis would be in order not only for the
    physical installation, but from the aerodynamic standpoint
    as well. They will work fine on all 260SE's,
    230SE's, Bushmasters, and Super Skylanes. I kind of like
    the speed brakes and look forward to more practice
    flights.Todd

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  • kwmoore
    replied
    The day I did the evaluation had winds down RWY
    22 at 10 kts, temp was about 50F and overall just a
    good day to play with the speed brakes. When
    coming down from a cruise altitude reducing the power to
    19"/2450 rpm seems to work well and generally provided
    about a 800 fpm rate of descent, with the speed brakes
    deployed. As I said earlier the airframe buffet with them
    deployed at speeds above 120 kts IAS is really noticeable.
    There are two warning lights (one for each speed brake)
    that are illuminated when the speed brakes are
    deployed. The switch is located on the control wheel and
    needs to be within easy reach. The descent from alitude
    was rather normal except for the higher power setting
    and airframe buffet. From a personal observation I
    would still probably slow the airplane down somewhat if
    I had non flying type passengers on board. Someone
    not familiar with flying might find the airframe
    buffet objectionable and I can see it making them
    uncomfortable (scared). Once down to traffic pattern
    alitude they were retracted and a high approach set up.
    Obviously if one shot a standard approach you would not
    need the speed brakes unless you just came out a
    little higher than you wanted. In this case they can be
    used very effectively to lose the excess altitude then
    be retracted for the balance of the approach. Pretty
    neat. In this case I just set up a high approach with
    20 flaps and used the speed brakes to regulate the
    rate of descent. For this they work very well. Once I
    had 55 kts established I turned to final about three
    times higher than I normally would have. Like the
    throttle and everything else I then used the speed brakes
    as necessary to get the stabilized approach that I
    wanted. I did not just deploy the speed brakes and ride
    the airplane down. I would deploy them at various
    times and then at other times I would retract them. Due
    to the wind, down drafts, etc. you need them at some
    point then at others you don't. The thing I really
    tried to do was leave the throttle pretty much in a
    fixed position and regulate the glide path with nothing
    more than the speed brakes. This is the same
    proceedure I used on the Wrens with the Beta Reversable
    Pitch Propellers I flew. While most approaches did
    require some power changes in additon to the speed brakes
    I think with sufficient practice you could really
    leave the throttle with enough power for the flare and
    run the entire approach with just the speed brakes.
    You can bet if I have this 260SE long enough this is
    what I will be shooting for. Normally when I
    reached an altitude of about 50 feet I would retract the
    speed brakes then continue the flare in a normal
    manner. You certainly don't want the speed brakes
    deployed during the flare as they kill lift and that's not
    what you want at that point. Here you need all the
    lift you can get to achieve the lowest possible touch
    down speed. Once the flare is made however and the
    airplane has just started to touchdown I then deployed
    them again to help kill the lift and get the airplane's
    weight transferred over to the landing gear for better
    braking. This technique seemed to work very, very well.

    Leave a comment:


  • kwmoore
    started a topic Testing speed brakes on the 260se

    Testing speed brakes on the 260se

    While the flight evaluation of the Precise Flight
    Speed brakes was not done with the detail of the
    GAMIjectors or the Vortex Generators it was none the less
    very interesting. The Speed Brakes are rather
    pricey. It seems to me like they run about $6,000 or a
    little more installed. Installation takes about three
    days. The quality of the kit is very good. They
    are designed to allow you to run a higher power
    setting on descent thereby keeping the chance of shock
    cooling the engine to a minimum. They are also designed
    to be used during final approach to the landing. I
    do not recommend having them deployed while going
    into the flare however. In my practice I used them
    during the approach, retracted them just prior to the
    flare then deployed them again just at touchdown. The
    technique worked well but you had to know what you were
    doing (like always). They are not speed limited so
    deploying them at cruise speed is an option. They do
    however buffet the airframe quite a bit at cruise while
    during the approach it is a very slight rumble in the
    airframe, due to the slower speed. It only takes a couple
    of seconds to deploy or retract them. The
    owners manual suppliment says that if only one should
    deploy it could be overcome with only a slight amount of
    aileron and rudder pressure. The only real
    downside I can see with these (other than the cost) is the
    fact that once installed you now have a rectangular
    hole in the top of each wing that the speed brakes
    cartridge is installed through. There obviously must be a
    hole up there to allow them to deploy also. Therefore
    you are going to have some rain come in through the
    hole but at the same time they provide a good way to
    drain the moisture out. As these speed brakes have been
    installed on Mooneys, etc. for quite a while I would think
    that if there were problems with the system it would
    have shown up by now. The rate of descent with
    them deployed give you an additional 1,000 fpm under
    most conditions without altering the power setting.
    They say that by deploying them at 23"/2450 rpm at 150
    kts IAS they will give you about 1,200 fpm rate of
    descent. I would say from my experience this is probably
    true, but at that speed they really buffet the
    airframe. Well with all this behind us it is now time to go fly
    the 260SE and see how well they actually work.
    The day I did the flight evaluation on was.....It
    looks like I'm running a bit long here so I will finish
    it up in the next post. Todd
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