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panamared505(at)brier.net
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 Posted: Thu Nov 29, 2012 1:34 pm Post subject: Spins in an RV-6 |
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Recently posted on the VAF:
| Quote: | The reasoning behind using the larger rudders (RV-8 at first, then finally
the late RV-7/RV-9 rudder) on the -6 was to help with spin recovery. You do
not want to intentionally spin a -6. It is capable of >spin recovery with
the original small rudder, but the spin develops very quickly and will take
much longer to recover with full recovery control inputs than what a
"regular spamcan" trainer airplane will do. In >other words, spinning a -6
will probably scare the holy crapola out of you and might make you panic
(and if you don't have enough altitude, then you know what happens next).
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I disagree. I have an RV6 with the small rudder and I intentionally spin it
almost every flight. I fly the IAC sportsman aerobatic sequence with it
and have no problems. One must just carefully watch entry and exit speeds
on some maneuvers. I do not like the term "gentleman aerobatics," it
implies to me that you fly the maneuver sloppily with a who cares attitude.
I fly each maneuver as precisely and as aggressively as possible (by
aggressive I don't mean violent, but when it is time to pull to 4Gs, then
smoothly, but quickly ...PULL TO 4Gs!).
As for spins:
1. It takes a positive prospin inputs to enter and stay in the spin. My RV
does not like to spin without aggressive prospin inputs, my RV has failed to
spin on numerous occasions (that gentleman aerobatic stuff).
2. Spin recovery:
a. Throttle off
b. Opposite rudder
c. And or Release back pressure (I find if I release back pressure too
soon the spin will stop before I apply opposite rudder)
d. If you do both as the Briggs-Meyer technique describes, then the
spin stops instantaneously.
3. Competition spins are only 1-2 turns, never more than two. To stay in
the spin beyond the first half turn requires that positive prospin inputs be
maintained. I do not spin more than 2 turns as there is no point for
aerobatic competitions.
4. Unintentional spins with power on. If you fly based upon airspeed, G
number and bank angle, how on earth would this happen? But if it does, spin
exit:
a. reduce power
b. release all controls
c. If spin hasn't stopped, apply opposite rudder
d. Reduce back pressure if any (my old flight instructor told me, you
can't spin if the wing isn't stalled). Van recommends forward push, point
is that elevator should go to neutral. NOTE: if you use to much negative
elevator during the recovery it is possible in some aircraft to do a
crossover spin, i.e. recover from a upright spin into an inverted spin.
e. Recover to level flight, then add power.
5. For a competition spin, after spin stops, aircraft must recover to a
vertical downline, then recover to straight and level. After the spin
stops, it is easy to recover to straight and level, don't need power. But
for competition spins it takes a significant amount of forward push to get
the aircraft into the vertical downline. NOTE: the idea of going to a
vertical downline is to gain sufficient airspeed to insure one does not
recover to level flight in a stall condition. This is really not a problem
with an RV.
6. If you find yourself in an unintentional spin, then you should be able
to recover in 1/2 turn or less (but it will take practice). Spins in an RV6
should be no more scary than any other maneuver. If you have never done a
spin, get a flight instructor to show you how. If you fear the spin, then
it is due to a lack of spin understanding and practice rather than of any
real danger, unless you are doing it less than 1,000 feet AGL! My
competition spins need 600-900 feet to complete, that includes the
intentional downline. I probably could do a 1/2 turn spin and recover in
less than 300 feet.
BTW, from an aerodynamic standpoint, higher vertical rudder is not the best
answer for increased spin recovery as the wing tends to blank out the top
portion of the rudder, more rudder below the horizontal stabilizer is much
more effective in an upright spin. Read Alan Cassidy's book "Better
Aerobatics" for an indepth explanation.
Anyway, that is my 10 years experience with spins in my RV6. Your RV6 may
be different!
Bob
RV6
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stein(at)steinair.com
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| Posted: Thu Nov 29, 2012 2:06 pm Post subject: Spins in an RV-6 |
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I would agree with much of what you said below, however having built and owned a number of RV6's over the past decades I will attest to the fact that the differences between planes and their configurations can be a HUGE factor in this particular airframe....specifically engine/prop combos, battery location, fuel levels, CG, W&B, etc.. Indeed some of them behave exactly as Bob mentioned below, but then again some of them are just absolute tigers (meaning they will wind up quickly and will NOT come out in a half turn no matter what you do or how good you are). My point of caution is that just because one particular airframe may behave that way and allow a quick spin recovery, my experience is that many -6's will not (and some -4's as well). I certainly wouldn’t out practicing for my first time with that assumption! In the end though, some of them do behave in the way that absolutely requires you to work hard in order to even get them into a spin (much less maintain it).
Just my 2 cents as usual!
Cheers,
Stein
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wdleonard(at)gmail.com
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| Posted: Thu Nov 29, 2012 2:58 pm Post subject: Spins in an RV-6 |
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I definately agree with Stein and Bob, they have not really contradiced each other. My RV-6 is clearly different than Bobs. While spin recovery is reliably prompt if recovered within one turn, fully developed spins are another matter. Recovery depends highly on development (how many turns so far), CG and loaded weight (heavier and more aft both slow recovery significantly), and spin direction (I have a heavy right wing so left spins recover easier). My engine and FP prop are rather light so I am usually more aft CG than a lot of RV-6's.
I have been in spins where static spin recovery inputs don't do it. Meaning, neither releasing back pressure nor holding the stick forward would allow recovery by itself (oppisite rudder being applied). The technique in my plane is to relase back pressure until the rotation slows, then briskly but smoothly move the stick forward before the spin develops in the oppisite direction. It is a very re-assuring feeing when you feel the plane start to 'fly' again.
The first couple of turns are steeply pointed downward and lazy feeling (except for the abrupt pitch downward). Developed spins are flat and quick enough to send all the fuel outboard in the tanks making the engine stop and oil pressure goes away. Quite a ride really. I loose about 400' per turn. I begin recovery no less than 6k' AGL. It takes 2-4 turns to recover from a developed spin especially if you don't do it right the first time.
Snap rolls are fun and recover instantly but seem to stress out the tail wheel linkages when I do them.
As for upgrading the rudder in the -6 the the 7/8 rudder - the main advantage there is the counterbalance, giving a wider margin from flutter. I know the rudder are also bigger, but I have never really felt that I needed more rudder.
That is my experience.
--
David Leonard
Turbo Rotary RV-6 N4VY
http://N4VY.RotaryRoster.net
http://RotaryRoster.net
On Thu, Nov 29, 2012 at 2:05 PM, Stein Bruch <stein(at)steinair.com (stein(at)steinair.com)> wrote:
[quote] --> RV-List message posted by: "Stein Bruch" <stein(at)steinair.com (stein(at)steinair.com)>
I would agree with much of what you said below, however having built and owned a number of RV6's over the past decades I will attest to the fact that the differences between planes and their configurations can be a HUGE factor in this particular airframe....specifically engine/prop combos, battery location, fuel levels, CG, W&B, etc.. Indeed some of them behave exactly as Bob mentioned below, but then again some of them are just absolute tigers (meaning they will wind up quickly and will NOT come out in a half turn no matter what you do or how good you are). My point of caution is that just because one particular airframe may behave that way and allow a quick spin recovery, my experience is that many -6's will not (and some -4's as well). I certainly wouldn’t out practicing for my first time with that assumption! In the end though, some of them do behave in the way that absolutely requires you to work hard in order to even get them into a spin (much less maintain it).
Just my 2 cents as usual!
Cheers,
Stein
--
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chasb(at)satx.rr.com
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| Posted: Fri Nov 30, 2012 8:35 am Post subject: Spins in an RV-6 |
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I agree with Stein that each RV-6 is different. I've only spun mine, but it seems to spin different than other -6 owners I've talked to that have spun their birds.
My -6 is reluctant to spin and requires full pro spin controls to enter and/or to stay in a spin. That includes spins in either direction, accelerated entries, slow, nose up entries, entries with and without power, and entries with various CGs. All seem to result in similar spin conditions with relatively slow smooth entries and very quick recoveries using only neutral controls. The rotational rate of my -6 spins is quite low though I have not timed them. The only disconcerting aspect is vertical oscillations while in the spin - the nose tends to vary 30° - 40° up and down with a very rapid transition from nose high to nose low and with two or three vertical oscillations per turn. I've only held the spins for two turns as the vertical oscillations are disconcerting and seem to increase in violence as the spin progresses. Two turn spins and recovery to level flight usually takes less than 1,000 feet of altitude with less than three Gs during the recovery. In fact, if the recovery is initiated with the nose going up, the spin stops with virtually no additional loss of altitude. I have not tried inverted spins and don't intend to.
My spin experience is limited in light airplanes with only a few spins in various birds. However, I have extensive spin experience in the T-37, with literally thousands of fully developed spins to include accelerated and inverted spins. The T-37 had a very stable spin, about 30° nose low, a very rapid loss of altitude, and a very high rate of rotation (a full rotation every three seconds in its slowest, most stable mode.) Its recovery required aggressive full anti spin controls resulting in a near vertical attitude following recovery. By comparison, my -6 spins MUCH slower, with a much quicker and much smoother recovery, but with the vertical oscillations mentioned above if held in the spin.
I encourage RV owners to familiarize themselves with their bird's spin entries and recovery. The emphasis should be on spin prevention, with no intention to fully develop a spin or hold the spin for more than a half turn. Those individuals with no previous spin experience should get some qualified spin instruction before trying it solo in any aircraft. Spins should be respected, but not feared.
Charlie Brame
RV-6A N11CB
San Antonio
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| Quote: | Time: 02:06:07 PM PST US
From: "Stein Bruch" <stein(at)steinair.com (stein(at)steinair.com)>
Subject: RE: Spins in an RV-6
I would agree with much of what you said below, however having built and owned
a number of RV6's over the past decades I will attest to the fact that the differences
between planes and their configurations can be a HUGE factor in this
particular airframe....specifically engine/prop combos, battery location, fuel
levels, CG, W&B, etc.. Indeed some of them behave exactly as Bob mentioned below,
but then again some of them are just absolute tigers (meaning they will
wind up quickly and will NOT come out in a half turn no matter what you do or
how good you are). My point of caution is that just because one particular airframe
may behave that way and allow a quick spin recovery, my experience is that
many -6's will not (and some -4's as well). I certainly wouldnt out practicing
for my first time with that assumption! In the end though, some of them
do behave in the way that absolutely requires you to work hard in order to even
get them into a spin (much less maintain it).
Just my 2 cents as usual!
Cheers,
Stein
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aerobubba(at)earthlink.ne
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| Posted: Fri Nov 30, 2012 10:34 am Post subject: Spins in an RV-6 |
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Guys, (and gals...), those three notes on spinning are three of the best written, concise, and non-hackle-raising notes I've seen in these fora. Kudos.
Glen Matejcek
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