Snaps in the Decathlon

Borislav Deianov wrote in message ...
Rich,

Rich Stowell wrote:
(Dave Russell) wrote in message . com...
Anyway, my snap rolls suck. The break is mushy, the rotation is
sloppy, my exits are horrible. The rotation is slow enough that I
actually can 'think' while it goes around, but I haven't been able to
get any meaningful acceleration with forward stick.

I have the same problem as Dave, except I'm flying a Citabria 7KCAB
(fixed pitch, 150hp). And it's only a problem when I fly solo. I can
do a reasonable snap roll with an instructor in the back.

Here's what I suggest you try in your airplane [Super D]:

Establish level slow flight at 85 mph. Leave the power alone
thereafter. Mentally give yourself a countdown -- 3, 2, 1 -- at 1,
smoothly but briskly apply full rudder as you would for any spin
entry. When you sense that the rudder is passing though 3/4 of its
full travel, "flick" the elevator aft just far enough to induce the
stall. At 85 mph, that'll be about a 2 to 2-1/2 G tug on the stick.
You want to generate that G with as little stick movement as possible.

Here are the steps I was taught for the 7KCAB:

- 1800 RPM, slow to 65mph
- 2200 RPM and lower the nose to accelerate to 80mph
- flick the elevator and as the nose goes through the horizon, briskly
feed in the rudder
- recover with opposite rudder and slight forward stick
- recovery seems to take about 1/2 turn rolling left, 1/3 turn rolling right

This works pretty well when flying dual but I'm always getting mushy
slooowww rolls when trying it solo (if I'm able to make it go around
at all). Any hints?

Thanks,
Boris


Hi Boris,

Of course, someone in the back seat shifts the c.g. a bit more aft,
allowing you to attain slightly higher angles of attack and better
stall/spin departures.

I would recommend trying essentially the same thing I suggested to
Dave for your solo ventures, namely:

In your Citabria, establish level slow flight at 80 mph. Leave the
power as is for now (later you can try adding a bit more power, but
for now, work on the rudder/elevator timing).

Lead the snap roll with brisk rudder application followed by
sufficient aft elevator to stall (about a 2 G or so tug on the stick).
As soon as the airplane departs, release a touch of the aft elevator,
etc.

I believe rudder-then-elevator will have better results for you than
the other way around.

Let me know how that goes and we can continue with the lesson!

Rich
http://www.richstowell.com

Rich Stowell wrote:
Borislav Deianov wrote in message ...

I have the same problem as Dave, except I'm flying a Citabria 7KCAB
(fixed pitch, 150hp). And it's only a problem when I fly solo. I can
do a reasonable snap roll with an instructor in the back.
[snip]

In your Citabria, establish level slow flight at 80 mph. Leave the
power as is for now (later you can try adding a bit more power, but
for now, work on the rudder/elevator timing).

Lead the snap roll with brisk rudder application followed by
sufficient aft elevator to stall (about a 2 G or so tug on the stick).
As soon as the airplane departs, release a touch of the aft elevator,
etc.

I tried this during my last session and I'm happy to report that it
worked very well! I was able to reliably snap it in both directions.
The roll rate was decent and accelerated a bit after releasing some
elevator input. Wow. I needed 1800 RPM to fly level at 80 mph.

The problem now is that the recovery after one turn leaves me in a
marked nose-down attitude. After a quick pull up to level flight, I
end up at about the same airspeed but 200' or so lower than the
starting altitude. Is there a way around that? More power and an
starting the maneuver more nose up, perhaps?

Thanks for you help!

Boris

Borislav Deianov wrote in message ...
Rich Stowell wrote:
Borislav Deianov wrote in message ...

I have the same problem as Dave, except I'm flying a Citabria 7KCAB
(fixed pitch, 150hp). And it's only a problem when I fly solo. I can
do a reasonable snap roll with an instructor in the back.
[snip]

In your Citabria, establish level slow flight at 80 mph. Leave the
power as is for now (later you can try adding a bit more power, but
for now, work on the rudder/elevator timing).

Lead the snap roll with brisk rudder application followed by
sufficient aft elevator to stall (about a 2 G or so tug on the stick).
As soon as the airplane departs, release a touch of the aft elevator,
etc.

I tried this during my last session and I'm happy to report that it
worked very well! I was able to reliably snap it in both directions.
The roll rate was decent and accelerated a bit after releasing some
elevator input. Wow. I needed 1800 RPM to fly level at 80 mph.

The problem now is that the recovery after one turn leaves me in a
marked nose-down attitude. After a quick pull up to level flight, I
end up at about the same airspeed but 200' or so lower than the
starting altitude. Is there a way around that? More power and an
starting the maneuver more nose up, perhaps?

Thanks for you help!

Boris


Glad to read things are coming along, Boris! Now for your next
practice exercises:

Exercise 1 -- Establish level slow flight at 80 mph and 1800 rpm.
Increase power to 2000 rpm and initiate a shallow, stablized climb at
80 mph. Perform snap rolls exactly as described earlier, using the
rudder-elevator sequencing.

Practice the same from a climb at 80 mph and 2200 rpm; then again
climbing at 80 mph and 2400 rpm.

Exercise 2 -- Establish level slow flight at 70 mph (probably still
close to 1800 rpm). Leaving the power alone, lower the nose *a little*
and allow the airplane to accelerate. Perform the snap roll as the
needle hits 80 mph.

Practice the same from 70 mph and 2000 rpm, 70 and 2200 rpm, 70 and
2400 rpm. In each case, lower the nose toward the horizon and snap at
80 mph. The idea is to sneak up on 80 mph from 70 mph, so don't stuff
the nose down when trying to accelerate form 70 to 80. Lower the nose
"just enough" to accelerate to 80.

These exercises are designed to steadily and incrementally increase
the rate of snap while still working on the timing of rudder and
elevator actions, all the while not exceeding 80 mph.

Also during the recovery, try not to move the elevator forward at all
-- just full opposite rudder and perhaps full opposite aileron if
needed to prevent over-rotating. You've released a little of the aft
elevator once the snap begins, and this may be all the forward you'll
need from that point on.

Report back...

Rich
http://www.richstowell.com