Testing speed brakes on the 260se

[kwmoore]

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

[kwmoore]

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.

[kwmoore]

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