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RV's won't spin inverted?..Oh yes they will..:D

frankh

Well Known Member
So it happened today..After I had convinced myself that it was not possible to spin an RV inverted I did a hammerhead (with a PX) and started to fall off it backwards...so what to do..well push forwards of course.

waited to see 40 knots still pushing, then a big bootful of left rudder..hardly moved..add a bit of right aileron and bang!..the thing snapped over really fast and it took me at least a whole revolution to realise what was going on.

Inverted, fully developed spin and it was moving round quite nicely thankyou very much!

I probably went round 3 or 4 times before I figured which rudder would stop the spin..I'm glad my harness was on tight cus I was thrown against it hard, as it was I don't think I managed to use full oppostie rudder.

So be warned doing hammerheads..It will spin..Impressively well.

My advice is if your starting to fall backwards near the top of the vertical..pull the stick back and let it fall off.

What a rush!!

Frank
 
I probably went round 3 or 4 times before I figured which rudder would stop the spin..I'm glad my harness was on tight cus I was thrown against it hard, as it was I don't think I managed to use full oppostie rudder.

As my instructor used to say in the Pitt's regarding rudder and inverted spins...

If that rudder pedal doesn't work, then use the other one!:D

L.Adamson
 
yes that was about it

I wasn't all that bothered about doing them when I trained with Steve Wolfe to be he=onest but he was pretty adamant I should know how to do them just in case.

I'm sure I would have figured it out before I got dangerously low but spin recovery from the invert I would consider to be a mandatory skill when doing hammerheads from now on.

Frank
 
The first couple of times I tried a hammerhead the plane went inverted. I spoke with an acro pilot that happened to be in the area the following week and he gave me a lesson on flying. He claimed that I had not come to a stop while going vertical and the wings were still producing lift. I went out and tried again and all has been well since. He had had some time in RV's and knew their characteristics. I can't remember his name but he flies one of those Russian acro planes which I can't remember how to spell. He was the Canadian acro champ at the time and representing Canada in the world acro contest.
 
Deja Vu! The first time that happened to me many moons ago in an RV6 I was caught pretty off guard. There you are, going straight up...then a little past straight up....then pushing on the stick....then airspeed going away....then BANG....the thing is spinning the wrong way upside down.

I remember landing after that ungraceful affair and telling a friend back and the airport that I just did my first inadvertent accidental inverted spin. Before I could explain, he laughed and said "Ya pig flopped over on yer back out of a hammerhead, didn't ya"!! (He's a pretty skilled Aerobatic pilot that had an Eagle at the time, now has a Pitts 12) and he knew right away what I did.

Anyway, do be careful. Hammerheads look so easy and innocent, but in reality can be so dangerous. These are great planes, but they will bite if you let them.

My 2 cents as usual.

Cheers,
Stein
 
hehe

yeah it got my attention..I was particularly impressed cus I have purposely tried to get the thing into an invert spin before..but just couldn't do it

Little did i know the hammerhead is a WAY more effective method..:)
 
Frank, thanks for the post and allowing others to learn from your experience. I am glad things turned out OK.

Luis Luciani
 
As my instructor used to say in the Pitt's regarding rudder and inverted spins...

If that rudder pedal doesn't work, then use the other one!:D

L.Adamson

Steve Wolf once told me, " If you're spinning and confused about which rudder pedal to push on, look at the pedals and step on the one closest to you."
 
0 time is RV's... but spun the T-34 a lot....

inverted spins were prohibited in the T-34C due thier disorienting nature... Test pilots did plenty of spin testing in it (think every edge of the envelope pushed) before I ever flew one... anyways We always were taught to use the turn needle to deterime the direction of the spin and step on the opposite rudder due to the tendancy of the pilot to misinterpret what rudder was opposite the spin... expecially an inverted spin...

we were also told that the only way to enter an inverted spin is to stall the aircraft inverted (ie negative AoA stall)... Inverted stalls were also prohibited inorder to prevent someone from entering an inverted spin).

again 0 time in RV's... and inverted spins... thanks for sharing your story for others benefit!

Tom
 
Can't do a -1G stall

Frank,
Thanks for the info. I went up last week with the intent of trying inverted stalls and spins in my 8. At a forward CG, I rolled inverted, and slowed in level flight. With full forward stick, the aircraft settled at 80 KIAS, descending at 1000 FPM. Three attempts all provided the same results.

I then moved on to my first attempts at Hammerheads. Did a half dozen or so and on couple of them I obviously got too slow, the controls had little effect, full left rudder, nearly full right aileron and full forward. The plane lazily fell off to the left, a real sloppy hammerhead. (It reminded me of my first solo in the T-38 when EVERYONE tried T-Bird vertical rolls, my airspeed was "0" at the top, I waited for the plane to fall, hoping the engines would keep going!) No spin, perhaps my forward CG was teh difference, where was your CG?

Anyway, I vowed to go back up and try the spins again on the next clear day. Figured I would have to aggravate the stall, perhaps from an immelman.

A couple days later, I had the opportunity to be critiqued by Sergio, the US Advanced champion. He told me I was waiting too long to kick and that I was using too much forward elevator. We corrected that and the Hammerheads improved dramatically though I still need to learn to feel when to kick.

Yes, I still need to go back and try the spins, hopefully, the weather will be good enough this weekend. I'll try your method a little more aggressively as well as the "botched" immelman method. I'm planning on competing in Sportsman this year and need to get this all down!

Scott A. Jordan
N733JJ
 
THIS POST IS USELESS WITHOUT PICTURES :rolleyes:

BTW, Thanks for all of your videos in the past.
 
Opposite rudder

If you enter a spin (either upright or inverted) after putting in a bootful of left rudder at the top of a hammerhead then it would seem reasonable to me that a bootful of right rudder (whether upright or inverted) will always be the correct response. Conversely the opposite should be true if you put in a bootful of right rudder at the top of the hammerhead.

The same should be true of any spin induced by a bootful of rudder (eg a snap roll). In other words whether upright or inverted a bootful of the opposite rudder to the one you used to induce the spin should bring you out (subject of course to taking the other usual steps....power down....ailerons neutral etc).

That might be an easier remedy for low time acro pilots to remember than trying to work out their spin orientation when inverted, particularly if inadvertently inverted for the first time.

I doubt that you could spin in the opposite direction to the original bootful of rudder. But I'd sure be interested to know if anyone thinks differently.

Incidentally Frank, after you found yourself in the inverted spin what exact sequence of steps did you take to bring yourself back to upright level flight.

A most enthralling topic.
 
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Pierre

Oil on the belly...Thats a sort of permanent state on my airplane..I do acro all the time and there is a nice corrosion proof sheen on the underside.

I have a Raven invert system and now I think about it I did not pull the power..Probably why it spun so fast..I once pulled the power on a hammerhead before rotating so I keep my hand clear of the throttle now, but I think in future I will have my hand on it.

So the engine never stopped making power..it was very happy to keep cranking out rational torque..:)

Frank
 
Steve Wolf once told me, " If you're spinning and confused about which rudder pedal to push on, look at the pedals and step on the one closest to you."

Frank, if you are comfortable recovering from all types of spins (accelerated, crossover, flat, etc.), I'd be curious to know how the Bill Finagin (Pitts master and IAC Hall-of-Famer) emergency spin recovery method works in the RV...never tried it in mine. Note: he limits his teaching of this technique to the Pitts only, which it works great in. No assumptions made for any other aircraft type.

Pull power, center the rudder and stick (do this VISUALLY so you don't inadvertently hold an input, thinking they're centered), hold this and wait for 100 mph on the airspeed indicator. Pull out. This is a good number that prevents overspeed on the pullout, but also provides a good margin against possibly pulling too soon and entering a secondary accelerated stall. Works for upright and inverted modes. This is an alternative to the opposite rudder and hands-off stick Beggs-Meuller method, which requires you to push the correct rudder.
 
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To Captain

If you enter a spin (either upright or inverted) after putting in a bootful of left rudder at the top of a hammerhead then it would seem reasonable to me that a bootful of right rudder (whether upright or inverted) will always be the correct response. Conversely the opposite should be true if you put in a bootful of right rudder at the top of the hammerhead.

The same should be true of any spin induced by a bootful of rudder (eg a snap roll). In other words whether upright or inverted a bootful of the opposite rudder to the one you used to induce the spin should bring you out (subject of course to taking the other usual steps....power down....ailerons neutral etc).

That might be an easier remedy for low time acro pilots to remember than trying to work out their spin orientation when inverted, particularly if inadvertently inverted for the first time.

I doubt that you could spin in the opposite direction to the original bootful of rudder. But I'd sure be interested to know if anyone thinks differently.

Incidentally Frank, after you found yourself in the inverted spin what exact sequence of steps did you take to bring yourself back to upright level flight.

A most enthralling topic.


Well as I said it jumped me..I have not done inverted spins since I trained with Steve Wolf two years ago..I am thankful I did.

So it snapped over making power and spun alrmingly rapidly and i was thrown hard against the belts.

I also have minor cuts on my shins where my feet were thrown off the pedals..By this time I was already at about 1.5 rotations.

I did not pull the power (mistake) as my attention was going for the pedals after I figured out I was actually spinning..Thought I may have been rolling at first.

I no doubt would have pulled the power if I had had my hand on the throttle and if applying rudder did not stop the rotation.

I did keep full foward stick until it stopped rotating.

Now the airplane recovered beautifully..better than a right side up spin but as I said I had power on so it was spinning very flat which was also confusing because right side up (with no power) it has a very nose down attitude.

Once i got to the pedals I had to feel them for half a second and pretty much went of the right pedal..I can't honestly remember.

I do remember thinking "work the problem don't panic..spin recovery"...

The whole thing about this is I didn't think the RV would invert spin..I have tried from the tops of loops see this

http://www.youtube.com/watch?v=TQIZQ2yti1Y

At 1.02 you can see where I attempted an invert spin..wouldn't stall... So I assumed the IS was not for this airplane.

I have done hammerheads up the waazoo and all this time had no idea just how close we are to the IS..I mean it wasn't that bad of a botch..just a slight falling over backwards..little push as the airspeed went away..then it started to fall over backwards..and there was zero time to recover from the incipient stage..it went from mushy botched hammerhead to fully developed spin in a couple of seconds.

So bottom line NEVER push at the top of a HH!..is your falling backwards, pull back on the elevator and tell your passenger that was a pull Humpty..:)

Alternatively use it to get into IS and have the video rolling..Its the only way it works, but it works VERY well!

Frank
 
OH yes

I have turn several upright left spins into right spins with opposite rudder.

Frank
 
Same here

Frank,
Thanks for the info. I went up last week with the intent of trying inverted stalls and spins in my 8. At a forward CG, I rolled inverted, and slowed in level flight. With full forward stick, the aircraft settled at 80 KIAS, descending at 1000 FPM. Three attempts all provided the same results.

I then moved on to my first attempts at Hammerheads. Did a half dozen or so and on couple of them I obviously got too slow, the controls had little effect, full left rudder, nearly full right aileron and full forward. The plane lazily fell off to the left, a real sloppy hammerhead. (It reminded me of my first solo in the T-38 when EVERYONE tried T-Bird vertical rolls, my airspeed was "0" at the top, I waited for the plane to fall, hoping the engines would keep going!) No spin, perhaps my forward CG was teh difference, where was your CG?

Anyway, I vowed to go back up and try the spins again on the next clear day. Figured I would have to aggravate the stall, perhaps from an immelman.

A couple days later, I had the opportunity to be critiqued by Sergio, the US Advanced champion. He told me I was waiting too long to kick and that I was using too much forward elevator. We corrected that and the Hammerheads improved dramatically though I still need to learn to feel when to kick.

Yes, I still need to go back and try the spins, hopefully, the weather will be good enough this weekend. I'll try your method a little more aggressively as well as the "botched" immelman method. I'm planning on competing in Sportsman this year and need to get this all down!

Scott A. Jordan
N733JJ

My CG is probably forward of yours..I have a 2.25" prop extension with a Hartzel BA prop.

I seriously doubt the botched immlemen will work.. see video..Maybe with a heavyish passenger it will?

Ok so on the HH...pull vertical about half way up over rotate to where your tempted to push forward..wait till about 40 knots and it should be about 10 to 15 degrees off the vertical (falling backwards) gradually go full forward stick as airspeed gest close to zero and add a bootful of rudder.

now wait for the fireworks..the thing should still be falling back and ever so slowly rotating left, power still on.

be warned it will snap over fast!

Frank
 
... and how about your back-seater ? (!)

Frank, this is a hilarious thread. In the first post, I saw that you had a passenger back there! Hope y'all are still speaking to each other!

Reminds me of my first inverted spin, it was in a T37. The Tweet spin recovery requires full forward stick to be applied abruptly. My student did just that, then locked his arms and left the stick there. That poor kid froze there like he was poured full of concrete. We transitioned right through the recovery cone into an inverted spin. I had to knock his arms off the stick to recover - FUN!
 
Its an RV7

Frank, this is a hilarious thread. In the first post, I saw that you had a passenger back there! Hope y'all are still speaking to each other!

Reminds me of my first inverted spin, it was in a T37. The Tweet spin recovery requires full forward stick to be applied abruptly. My student did just that, then locked his arms and left the stick there. That poor kid froze there like he was poured full of concrete. We transitioned right through the recovery cone into an inverted spin. I had to knock his arms off the stick to recover - FUN!

Funny..I don't often do hammerheads with Px's..probably less than half of them are up for it so I probably don't get to practice them as much as I should.

But yeah he loved it!
 
Great Thread,

Bill, Something similar happened to me while teaching spins in the t-34C. A girl student did the spin, then the recovery, then froze on the stick nearly full forward. You can not over ride even a 115# female with two hands on the stick and her arms locked!! After passing through the vertical, into about a 45 degree nose low inverted dive/beginning of an outside loop, and some pretty emphatic stick banging by me (that was our routine "I've got it" signal), she let go. Great, now what?? After a few micro seconds of thought it all became clear - roll level idiot!

Thanks for the great thread Frank. I am just getting back into acro in the -6 and I will keep this in mind as I progress into HH.
 
hammerheads

It seems to me that doing a true hammerhead (i.e. 0 airspeed at the top) may be unhealthy. If you miscalculate a little at the top and you start a tailslide I am not sure that the tail feathers will sustain the reverse airloads.
 
They won't

I spoke to Vans about this and also someone else on VAF commented they had seen damage on an RV that had been tailslid.

Gus at Vans was adament the RV's are not designed for tailslides.

Having said that I usually rotate at the top of hammerheads at around 40 knots..if you do it too fast (60+ say) it won't rotate..it sort keeps going up partially rotated..No big deal, just wait and it will go over eventually.

as long as its not falling backwards of course..:)

Frank
 
FLAT SPINS

The factory Lycomings in the certified aerobatic aircraft have heavier crankshaft flanges. I assume this is also true of the aerobatic aircraft such as the CAP and certain Extra models etc that are not certified. The flat spin is considered a gyroscopic maneuver as far as crankshaft loads. The Hartzell C/S and extended prop both cause significant additional loads on the flange. I know of one heavy flange/hartzell prop that departed the aircraft at 300 hours since new.
This issue has become rare because most people doing gyro maneuvers have switched to MT or Whirlwind or similar props, including the very expensive Hartzell with carbon blades.
I am not an RV pilot but most of the following is generic regarding hammerheads and tailslides:
A hammerhead is not a zero airspeed maneuver except in the very high powered airplanes like Sean Tuckers. It is a very low airspeed maneuver. The higher the weight/horsepower number, the higher the speed for the hammerhead. A good test of when to "kick" is to slowly put in some right stick, if the airplane does not roll significantly to the right its time to kick. The Pitts requires full right stick and a bit of forward stick as the rotation starts. If the airplane is falling on its back(nose coming up) just before the hammerhead, the safe bet is to abort the maneuver, neutral rudder and GENTLY help the nose in the direction closest to the horizon. Stop the pitch at the horizon and roll upright. In the Pitts the majority of all spins out of botched hammerheads are inverted.
The only time an inadvertent tailslide would be an issue in the RV would be if the engine stopped completely just before the turnaround. In the unlikely event this should happen, if you can get the pitch at least 10 degrees off the vertical, it is unlikely that the slight resulting slide would hurt an RV. The most dangerous situation in a tailslide is letting the controls get away from you to the point they slam against the stop. Intentional tailslides, in the aircraft approved for them, are done at idle power. The earlier the power is brought to idle, the better the odds of a good slide.
Regarding inadvertent spins, there is no guarantee the hands off or neutral controls method will work in the RV's. And what works one time may not work the next because of slight changes in cg. So the safe bet is to know exactly what is needed for recovery. Throttle to idle and hold it there, full opposite rudder-look straight out over the cowling and apply rudder opposite the yaw. THEN stick back for inverted spin recovery. Don't yank the stick back to the stop but move the stick deliberately. The rotation should stop with the stick slightly aft of neutral. To greatly oversimplify things, in an inverted spin the RV tail is operating in much cleaner air and the recovery should be noticeably cleaner than an upright spin.
There are probably two main reasons why intentional inverted spin entry from inverted level flight is so difficult in the RV's. CG too far forward and or not enough available down elevator. The Pitts S2B does not like to spin inverted flat from a level entry with forward cg. From other attitudes with forced entry, it spins very easily. Examples are from a verticlal upward roll. a hammerhead, or an immelman. I know this got very long winded, but I have known at least three people over the years that came extremely close to killing themselves in RV's doing acro and having things go bad. The most memorable was a gentleman who admitted to being WAY over redline and just a couple hundred feet above the ground when he recovered(RV6).
 
The factory Lycomings in the certified aerobatic aircraft have heavier crankshaft flanges.
Is that true anymore? I thought that all Lycoming 360's these days have the 0.44 flange with no lightening holes, and the only difference with an "A" prefix engine is the inverted systems. (And a lower TBO, because they assume it will be flogged.) But I'm not an A&P and a lot of Lycoming lore is just rumors by the time it gets to me. :confused:

--Paul
 
LYCOMING

I haven't kept up with all the changes in recent years. The bottom line is that even with the heavy flange, it won't hold up with the hartzell metal blades for acro and even the short extension greatly increases the loads on the flange when doing acro. The lightening holes went away a long time ago. I have gotten conflicting info on this but I believe around 1968. I have tried to correlate elimination of lightening holes to narrow deck/wide deck transition which I think was somewhere in late sixties, but nothing definitive on this either.
 
Knowing when to... in the Hammerhead turn

There is a lot more, aerodynamically, than meets the eye in this most beautiful of manouvers. In my Pitts (and after some pretty serious sessions with the likes of Gentleman Steve Wolf), I have learned, through practice, to judge the moment of truth by looking out at the left wing. The amount of right aileron deflection needed to keep things in line with a reference point on the horizon becomes a sort of speed indicator. (About one inch in my airplane). As the ship pinwheels, I keep that point in view by rotating my head 90 degrees to the right as the nose arcs down toward the horizon. The horizon reference point can then be nailed inside the cabane strut. Once that is done, I'm free to look down at the ground, pick the most convenient weed, and head straigt down for it.... A most exhilarating rush, especially with smoke, as one is headed down beside the column that has just been laid out on the upward portion of the manouver. The most difficult thing to do is to keep one's eyes outside the cockpit. Frequent consultations with the airspeed indicator will only result in losing the reference point on the horizon. I must confess to having cheated a little in the beginning by taping a two-foot long yarn to the interplane strut, but after a while, one begins to undestand the "feel" of the airplane as the time for rudder input arrives.
The need for additional right aileron input as the airplane begins to gyrate is that the right wing, now accelerating over the left, generates lift. Also, the engine, developing the full power necessary to make the aircraft turn, creates a gyroscopic force. These two phenomena have a tendency to put the aircraft on its back, so that additional aileron and forward stick inputs are essential, as is the know-how to extricate oneself from the unanticipated inverted spin. Altitude, and plenty of it, can save a botched manouver and turn it into a momentary embarassment, instead of a lethal outcome. Also, if at anytime I find myself thinking, or saying "watch this", I end the aerobatic session immediately.
I do not believe any aerobatics should be attempted without the proper equipment, including parachutes, and should only be done after thorough and repetitive instruction from those recognized as experts in the industry. Mental and physical fitness must be constantly maintained, as I know personally that the demands of aerobatic flight are on a par with formula car racing.
I have not flown aerobatics in RV aircraft, but I have been a passenger in them during acro flight. All that applies to Pitts' can be fundamental in the mechanics of the manouvers, but an RV is a totally different airplane, and my comments above may not apply to aerobatic flight in RV's. Again, instruction is the key to safe, enjoyable aerobatics.
Respectfully submitted,
TN
RV-8 QB (Project for sale, deposit received)
Pitts S2A (Flown at Sportsman level)
Cessna 180
 
This is a great thread and thanks Frank for the info on the inverted spin. In the Sky Dancing Youtube with my RV-4: http://www.youtube.com/watch?v=j9VZBZ2h7U8, there are three manuevers in the sequence that could induce the inverted spin- the vertical roll to hammer head, the inverted climb to roll, and the inverted loop at the top. What you don't see, is that I make sure I'm not exactly vertical for these maneuvers. On the vertical roll to the hammer head and the inverted climb, I'm slightly less than vertical. On the inverted top of the loop, I go past the vertical before I roll 90 degress, again to avoid the possibility of a tail slide. Before I did any of the multiple verical manuevers, I found out how many seconds I had for a given airspeed before I ran out of airspeed. Please be careful out there so we keep that RV grin with these magnificient airplanes without having to change our pants.
Bill Mclean
RV-4 inverted systems
Sky Dancer
 
HAMMERHEAD

I just watched the video of the Foreign RV6 Airshow. All very impressive except the hammerheads which are not very good. The yaw rate in the turnaround appears very slow and the right wing is rising, especially noticable in the last portion of the pivot. Does the RV6 not have enough rudder for a clean hammerhead??
In the Pitts S2B the basic maneuver that is most likely to produce a flat spin is the immelman. heres how it goes: new student, struggling with at least some of the basic maneuvers, hazy day with a not very clear horizon. Looping portion starts out ok but instead of watching the wingtips, the student gets fixated on the nose. Surely the half loop must be finished but can't see the horizon over the nose so lets roll this sucker upright and find out where we are. Only problem is the nose is 30-45 degrees above the horizon and airspeed is decaying. Full left aileron and a generous amount of left rudder. Somehow they decide the roll should end and move the stick smartly to the stop to the right. Some left rudder is still in play as well as a bit of aft stick, and the airplane upright flat spins to the left. In 16 years of flying the Pitts S1S I had never experienced an inadvertent spin. They became a daily event when I started instructing in the S2B. I call it the immelspin.
 
Botched hammerhead

Just to bring back a good thread FrankH had on RVs and inadvertent inverted spins with RVs with a hammerhead. Here's what FrankH was trying to describe on the third attempt: http://www.youtube.com/watch?v=GLed3Zg40mI&feature=plcp The only difference is when it got over pitched, I pulled the power back as it started to yaw and used no rudder input. This is exactly as I learned in an Extra 300, practicing advanced acro and:eek: botched maneuvers, which puts minimum stress on the aircraft.
Bill McLean
RV-4 slider
Alabama
 
Hey Bill, see - there's no cure for this aerobatic sickness. :D I liked your torque roll in one of those...not many RV guys doing those. :) Yep, best one was the last one. Just curious - I assume you're looking over the nose as you stop the pivot? I did that at first and was never able to consistently stop the airplane perfectly vertical in both pitch and yaw axes after the pivot, since it's hard to gauge this by looking over the nose. It appeared several of your pivot stops ended up with your left wing a little low (under pivot). Regarding pitch, you were a little negative after the first pivot, and positive on the next three, and pretty close to vertical on the last one, but a tad bit negative. I'm sure you've noticed that if you're negative after the pivot, the left wing will rise during your vertical roll down...and the opposite if you're positive after the pivot.

I get much better results by watching the left wing during the start of the pivot, looking over nose as the nose falls through the horizon (to check for squareness), and then shift my view back to the left wingtip to "fly" the sighting device back up to the horizon. I can watch the sighting device approach the horizon and see if I'm off in pitch or have applied too much or too little forward stick. And I can also better time the right rudder input so that the airplane stops perfectly vertical in yaw without any "penduluming" or dragging a wing down...well if I'm lucky, anyway. :) Again, just fly the sighting device to the horizon. From there I immediately shift my view back over the nose for the downline. Your "sighting device" on your canopy could be used the same way.

Last thing I'll mention is that it appears in a few of your hammers that the airplane is starting to torque roll left slightly just before you apply left rudder. It appears your ailerons are neutral at the start of the pivot. Most airplanes that have a high power/weight ratio need a degree of right aileron before the rudder is applied to control torquing before and during the pivot.

It appears you are waiting until the pivot is almost complete to apply right aileron, which is being held after the pivot stops and is rolling the airplane back to the right a little. I assume this is now rolling you back to your original heading to correct for the initial torquing to the left at the start of and during the pivot. In general, any right aileron you've applied at the start of the pivot should be removed either immediately or just a moment after the pivot stops. With my metal prop on the Pitts, I needed to hold full right aileron a moment longer than I now need with the lightweight Catto. Also, any forward stick you're applying will need to be the first input you remove as the pivot stops, since the gyro forces stop as soon as the yaw stops. But since airspeed is so low, and due to residual torque, you might need to hold the aileron input for an instant after the forward stick is removed. The stick inputs at the start of the pivot are removed in the reverse order at the stop. Starts with right aileron then forward stick (simultaneous with rudder input), then at the stop remove the forward stick immediately followed by the right aileron. Think of the stick movements as a gear shift pattern in car...as if you're moving the stick from neutral to 5th, and then back to neutral. I wrote all this here incase anybody else actually cares. :)

This is one way video really helps with self-critiquing. I'm sure you've noticed everything I mentioned. Hammers are so simple right? :) But a perfect one is the prettiest maneuver there is, IMO.
 
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i don't do aerobatics (isn't acrobatics for gymnasts ? ) but I was under the impression that when you do hammer heads, you add a touch of power to induce additional yaw as well as give a stronger rudder/elevator authority

could that be the cause of some of these lazy "over the top" behaviors that some have observed out of their planes?
 
INVERTED SPIN

Good discussions from your post - thanks! I'm nervous about doing inverted spins in my -8 (if it's ever done) because of the ultimate load factor of 4.5 neg G's Vans suggests and light RV control forces. When doing inverted spins in our Pitts both I and other pilots have gotten to -4.5 G's, partly because these were competition recoveries to a vertical down line. Did you notice the maximum neg G you got during the recovery? EFIS or telltale on the G meter probably told you and I'd be very interested to know what it was. Probably a lot less than that -4.5. But I do worry because adrenaline fueled, confused pilots can apply pretty strong control inputs. Glad you are down and safe. Regarding lightening holes in crank flange, they were still around in 1981 when we got our Pitts S-2A. The engine is a 200 HP wide deck (inclined valves) manufactured the same year. Ours was checked at about 1200 hours with a magnetic slurry/dye and eddy current device and pronounced as good as new. 10 hours of flight time later 4 of 6 webs between lightening holes were cracked on routine exam with a 10 power magnifier. We have a solid crank now and no trouble in 600 additional hours with lots of autorotational maneuvers. Thanks again for your spin story.
 
i don't do aerobatics (isn't acrobatics for gymnasts ? ) but I was under the impression that when you do hammer heads, you add a touch of power to induce additional yaw as well as give a stronger rudder/elevator authority

No, full power should already be in on the vertical line up and it should remain there throughout the maneuver. A minority of folks who fly very high-powered, metal prop, stubby wing airplanes (Pitts) prefer to actually make a power reduction during the pivot in an effort to control torquing. But I disagree with this technique. I had problems at first with torqued hammers in my 180hp metal prop Pitts S-1S, but it was a technique problem, rather than a power problem. Reducing power is only going to make your pivot more lethargic. Torquing problems can usually be fixed with technique - proper timing of the pivot (no need to kick too early) and the proper amount of aileron and forward stick. Most important is that the forward stick be applied absolutely simultaneous with the rudder input. There are some aerobatic books out there that describe a sequential application of rudder, aileron, and then forward stick. Yes, some right aileron is typically applied before rudder, but if you wait until after the rudder application to apply forward stick, you're simply gonna torque the hammer when flying a high-torque airplane like a metal prop Pitts, etc. IMO, forward stick should always be concurrent with the rudder application (and removal).
 
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Good discussions from your post - thanks! I'm nervous about doing inverted spins in my -8 (if it's ever done) because of the ultimate load factor of 4.5 neg G's Vans suggests and light RV control forces. When doing inverted spins in our Pitts both I and other pilots have gotten to -4.5 G's, partly because these were competition recoveries to a vertical down line.

Bill, the only time I ever came close to negative G like this during an inverted spin in the Pitts was after a deliberately botched hammerhead where I pushed full forward stick and kept full power and rudder in. But this was more of an accelerating outside snap than a spin. Negative G's were increasing before I pulled power. I do competition inverted spins in the Pitts, and these are pretty much -1G maneuvers, just like a power-off upright spin is pretty much a +1G maneuver. The airplane really doesn't know the difference between an upright and inverted spin - the mechanics are identical. You don't necessarily have to push out of the vertical downline to inverted level flight. Once your'e vertical down you can either push or pull out. Most will choose to pull. :) A pushout really has nothing to do with the inverted spin itself, and would be the only time you should see high negative G...it shouldn't be during the spin or the spin recovery itself. It's hard for the G to increase much either way if the airplane is fully stalled and power is off. And since the inverted spin recovery requires you to PULL rather than push, you're actually unloading any negative G during the recovery to a vertical downline.
 
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Having never aerobatically flown an RV, I can't say for sure if this applies but I have always preferred inverted spins to upright in contest flying for a couple of reasons. One is, you can see much more of the box and place the spin exactly where you want it. The other is better control - When you are inverted in most aircraft you have less of the rudder blanked by the HS, and a much more precise control on stopping the spin exactly on heading. Again, I don't know if this last is true in an RV, but I am looking forward to finding out!
 
thanks for the acro experts

We are so fortunate to have input from Eric and Damon, etc. who have had extensive competition aerobatics to help the RV community learn to safely apply this knowledge to our magnificient machines. They have made good points that each aircraft is different, and may not respond like other RVs or acro types. In the CAP 10, we applied opposite aileron just after applying left rudder for the pivot. I'll try applying right ailron before the rudder and see how it works. My Oregon RV-4 buddy who has extensively modified his RV for competition made a visit to lower Alabama this week, and we discussed mods to make the RV more aerobatic competitive (more ailerons, tapered wing, CAP 232 rudder, semitrical wing, etc.). Always hoping other RVers will join the fun we have at the local IAC chapter competitions.
Bill
RV-4 Slider
 
A inverted spin will have you hanging in the straps not pinned to the seat. Bailing out however will be very difficult from a RV in either situation. Most aircraft including from reading this and other forum the RV recover much better inverted then upright since the rudder is in clean air inverted.

George
 
How would you bail out if the inverted spin didn't go as planned? Is there an exit strategy? I'm thinking the inverted spin will keep you pinned to the seat.

More like an inverted spin will help eject you from the cockpit. Think about what negative G does. Trained aerobatic pilots don't think in terms of "how will I bail out if I can't stop a spin?". They think in terms of, "what is my emergency recovery technique?" But if there are cirumstances beyond the pilot's control that require a bailout, the pilot doesn't much care if the airplane is spinning or not. The procedure is the same...you just get out as fast as you can.
 
inverted spin and ejecting

For you IAC members, the May 2011 Sport Aerobatics has an excellent article ("23 seconds") on bailing out during competion. The good news is that it is very rarely needed, but the bad news is that it is rarely successful. My instructors twenty years ago (French Connection) had wing contact during a side by side hammerhead, which would have been at the top of the acro box, and they didn't get out. As Damon pointed out, the inverted spin is actually easier to keep orientation with practice, and in my RV, I lose less altitude, and end up with a lower vertical airspeed for recovery.
Love these RVs,
Bill McLean
RV-Slider
Lower AL:eek:
 

Those old training videos are always entertaining. Nothing like a windmilling prop while spinning inverted. Just don't try it with a wood prop unless you have a starter. :D

I find it odd they stressed moving the stick fully aft during recovery. I've never flown an N3N period, much less spun one inverted, but in most aerobatic airplanes, moving the stick fully aft after applying opposite rudder will cause a textbook crossover spin. While we're posting videos, here's one I shot of two crossovers - upright to inverted and back to upright. The back to upright part used the exact same inputs shown in the N3N video.

http://www.youtube.com/watch?v=s-S6qx5Mo-E&feature=plcp
 
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Those old training videos are always entertaining. Nothing like a windmilling prop while spinning inverted. Just don't try it with a wood prop unless you have a starter. :D

I find it odd they stressed moving the stick fully aft during recovery. I've never flown an N3N period, much less spun one inverted, but in most aerobatic airplanes, moving the stick fully aft after applying opposite rudder will cause a textbook crossover spin. While we're posting videos, here's one I shot of two crossovers - upright to inverted and back to upright. The back to upright part used the exact same inputs shown in the N3N video.

http://www.youtube.com/watch?v=s-S6qx5Mo-E&feature=plcp


Eric, that is a fantastic video. DR should start a new thread in the "Safety" section titled "crossover spins" and put a sticky on this video! If I may be so bold to suggest, maybe you could re-edit the video with captions indicating your control inputs as the spin progresses. Videos like this, with a description of control inputs as they go, should be required watching for anyone who does aerobatics. (As a supplement to actual training, of course!) I have no hard data, but it has always been my suspicion that most spin related accidents in aerobatics result from the unintentional crossover spin - more specifically entering an inverted spin from the upright, because of overzealous and/or badly timed control inputs, and then not recognizing what has happened.

Watching this video, notice how during the upright portion, the nose oscillates from almost vertical down, then back toward level flight, maybe about 15-20 or so degrees nose below the horizon. During the inverted portion the nose oscillates from near vertical to again about 15-20 or so degrees below the horizon, only now the aircraft is inverted.

Most importantly notice the direction of rotation NEVER changes as the spin transitions from upright to inverted, even though Eric, who started the spin with right rudder and back stick, now has full left rudder and forward stick applied!!!

As an inexperienced pilot at this point, you might be thinking something like "OMG, I just did what I was taught to do for a spin recovery, but the plane is still spinning! What do I do now?!"

The differences in view are important, and also the sensations you feel, if you are not too panicked to notice. During the inverted portion you will be coming out of your seat, hanging on the belts, and instead of the nose going from vertical to close to upright, you will be going from vertical to nearly fully inverted.

I urge everyone interested in acro flying to watch this video a lot, and if you know an experienced acro pilot, have them describe what Eric's control inputs are. And then go fly with someone experienced. Of course the sight picture will be different in a Pitts, with the top wing in the way, but as I found it quite difficult to do a crossover spin in an Extra 300L, (they just want to recover too badly instead of crossing over), I recommend you fly a Pitts for all spin training, they spin much easier. And inverted spins are so easy to recover from, as I said before even easier than upright spins in all planes I have flown. That makes it all the more a tragedy when someone falls victim to one.

Again, fantastic video Eric, thanks for posting!
 
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Spins

You folks should read this starting page 177 of this IAC file. There is much good reading all through here also. You can read what the stress will do to hard core aerobatic aircraft. Our RV airplanes are not built this hardy. The RV is a great design and will do many things well though.

http://members.iac.org/technicaltipsmanualvol3.pdf

SPINOFFS
Herendeen & Beggs Add to Story

I have preached this for several years and it has saved a few pilots. All I have helped into acro received a copy. I have owned some aerobatic airplanes, Pitts and Eagle II, Ultimate 10-200. I have flown many others over the 30+ years of acro. The closest aerobatic plane to my RV-4 was my Siai Marchetti SF260.

The RV,s and SF 260 are airplanes, I feel are suited to what I call Zoom Aerobatic Aircraft. They are not aircraft for departing normal flight at low attitudes. My RV-4 has an 180 & CS prop with inverted systems, I also converted my SF 260 for inverted flight. Neither do well inverted due to the design.

One thing to remember, the more you fly acro, the less you feel the G. The body will build up G tolerance, the RV will never get any stronger than when it was built, this can lead to airframe problems. There has been many airplanes that have been destroyed by exceeding the limits and pilot's limit. In a few years time I was pulling 8.5 G on many flights. It was a good thing the aircraft ran out of energy to hold it, as I never found my limit.

If you Google N38PC, you can read the results of the demise of my Ultimate 10-200. Thankfully the pilot had the experience and was disciplined enough to live up to his plan. I had sold N38PC as I had been away from high G acro for about 10 years. When I purchased N38PC, I had lost the interest in the type of flying it was capable of. I had already been flying my RV-4 and a few other aircraft we had at the time. Age took away some of the fire.

Being self taught and flying many aircraft W/O a chute, or A/C able to get out of and finding myself with less than the required air below me and unable to depart, I count myself more lucky than skilled at that point in time. I had more desire than planned options.

If this helps one person, I will be happy. Be safe and have fun.
Gary
 
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Inverrted spins

Eric- Sorry to take so long to respond. I agree with you that the spin and recovery don't generate high G's. But a push out from a competition vertical down line can get high negative G's. OK, a pull out isn't likely to be any problem with 6 G's available and no structural concern, but it is a perfect set-up for G induced LOC (loss of consciousness) during the pull out. This can lead to 15 seconds or more of unconsciousness followed by a further period of disorientation and confusion - ask me how I know! To avoid this some pilots prefer the push-out; I worry about G loads that can be caused then in a plane with light controls like an RV, and a possible structural failure at about 4.5 G's. Unlikely? Wouldn't occur with a skilled pilot familiar with inverted spins, but still a concern, if the pilot is inexperienced and a little scared. I've spent some time checking G meters after competition flights and seen many negative telltales pinned or at 5-5.5 G's. While I usually adhere closely to all airframe limits, after one competition flight I had pulled 8 and pushed 6 G's. In the heat of battle I must have ignored the meter for awhile, and it didn't feel any different than any other competition flight. Don't think I'll do them in the -8 but if so would plan a gentle pull and recover upright. There was a nice article on spins of all types in the RV-8 by an English gent, published in the RVator IIRC he had no problems with inverted spins, whether normal accelerated or flat. It's well done and a good read!
 
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