Flying the Sonex

The following was taken from the “Sonex Talk” yahoo group. Posted 3/17/2010

“Here’s some Sonex-specific comments –

For 2 people on board, it doesn’t much matter if you put the stick full forward on takeoff (no flaps). The tail won’t come up until there’s some speed. Solo, tail will come up about 1200-1300 rpm (3300 engine) whether there’s forward speed or not, so I could see putting the prop in the dirt if you are too aggressive with the stick forward.

Since the flaps are big pitch down moment, I can see how first notch helps lift tail at higher weights. I’ve only done that a few times, as with the big engine it likes to run out of the white arc pretty quick, even in climb.

I was doing some simulated engine outs last weekend (to the runway), and did one w/o flaps to see the difference. Ok, a bit longer on the glide, but man, once over the runway, just floating, floating, floating.

This wing so close to the ground, I think you want flaps for all landings. I fly from a 6900′ runway, so a 1/2 mile of floating isn’t a big deal, but it would be if the field isn’t that long! It is extremely low drag compared to strut-braced high-wings. Flaps here aren’t so much to change the lift, wing area & loading as to add drag. – Eric W./Jab 3300



“Flaps on the Sonex are very useful for slowing this slippery bird down
when landing. You will notice that without flaps the speed will build
quickly with the nose pointed at mother earth. The flaps also will
give a better view over the nose when landing.

I generally use 10º of flaps and 80 IAS for take-off until I’ve
cleared all obstacles, and then clean up the flaps and lower the nose
and climb at 100 IAS.

For landing I set the first notch (10º flap) abeam the touchdown point
at 85-90 IAS. After turning base I slow to 80 IAS and add the second
notch (20º flap).

I fly final at 70 IAS when solo and a bit faster when heavy. Whether I
use the 30º flap setting on final depends on what the approach looks
like. I like to come in a bit high and the last notch of flaps will
really help slow it down and get it down, especially with the throttle
at idle. If I still need more down elevator I will use a bit of slip
to bring it down. Over the numbers is in the 60 IAS range and again a
bit more when heavy.

Landings with 20º flap is easy enough with plenty of runway. Add a
bit of power in the flare and it will “squeak” onto the runway. I’ve also practiced a few “no flap” landings when doing emergency
procedures.

Hope this is helpful … – Dale/N28YD

“Jeff,
I saw your post on Sonex Talk ref flaps. I feel I must give you a caution:
Be very careful using flaps 30 as it causes a lot of drag.

If you pull the power off with flaps 30 and are a little slow the plane will
drop around 1,200 FPM. Remember the Sonex has a “Hershey bar” wing – small
with a high wing loading. Just the opposite of a Cub with a huge wing and
which will float.

I have decided (after one very hard landing that caught me by complete
surprise) to never use flaps 30 again and have even put a little cover plate
on the flap position angle, blanking off the 30 position. I always land with
20 degrees.

On another flap related item – the Sonex plans do not call for the little
safety “nib” on all the flap positions, I believe they only call for it on
the 30 position. Three times I have had my flaps slip out of the position
they were in and blow up due to the high wind force against them and the
fact that I did not seat the flap handle all the way into the notch. When
they blow to the up position you instantly lose a lot of lift and the plane
suddenly drops. Fortunately all three times I was not low to the ground or I
might have hit. This scared me so much that I have now added a safety nib to
all flap positions to prevent the flap handle from coming out.

I hope this is helpful to you.

Phil Simon, Sonex #492 (300+ hrs, 20,000 miles XC, landed in all 48 states)
11 Marine Drive
San Rafael, CA 94901

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