RV Spin Entries (Competition)

Rather than hijack the thread congratulating Bill, I thought I'd start a new thread. Scott, in that thread you wrote:

N733JJ said:

I flew Primary and then Sportsman in my 8 for a few years. Had a great time, only embarrassed myself once (hammer), had to "educate" the judges about RV spin entries or they would have zeroed me most of the time. :-( they were generally pressed with what the 8 could do. Then, as now, the IAC was trying to. Get more Rv's to compete, I even had a discussion with Vickie Cruz and some board members about RV's in Sportsman vs a type class. I liked Sportsman but they made the spin a 1 1/4 that year and I never could stop in consistently. I lobbied for a one or a 1 1/2 turn as the rotation picks up (at least in my 8) right at one turn and that made the 1 1/4 tougher than a 1 1/2.

Scott A Jordan

Click to expand...

What were the challenges you found in your particular airplane (RV-8) that caused problems presenting a proper spin entry to the judges? You mention the need to educate the judges on "RV spin entries". Since there is such an extremely small sample of RVs participating in IAC competition, I have little experience watching and judging them outside of Bill McLean (RV-4) and Ron Schreck (RV-8). But both of them do very nice spins, supported of course by their high scores. Ron and his RV-8 do a beautiful 1-1/4 spin (in this year's Sportsman Known). My RV-3 spun fine once I learned its quirks. Even in my Pitts, I must employ some technique beyond simply holding full forward stick and rudder to get a decent inverted spin. It's all part of problem solving and learning what it takes to make the airplane do what you need it to do. Not sure how far you took this process.

I might caution against describing "RV spin entries" as being problematic and needing special consideration or accommodation by the judges...generally speaking. Every airplane is slightly different, but there are lots of little technique tricks you can employ to clean up the spin entry and rotation, up to even securing ballast to adjust CG. I just don't want anyone to think that RVs have problems or "special needs" issues when it comes to operating in the current competition environment. This could be seen as discouraging. There's been plenty of that in the past - not by you of course, just in general by folks with little or no experience with this sport. Although with the success of Ron and Bill, the naysayers really have no legs to stand on.

1 1/4 spin

Scott,
As Eric stated, finishing on a specific heading for a 1 1/4 spin is technique and practice, practice, practice. For the last contests posted for the Carolina Boogie, for three sequences of the Known, Ron Schreck in his RV8 had a low score of 7.7 and a high of 9.2 out of 10 averaged for the judges. That's getting it right. I don't know what Ron's spin scores for this East Coast Championship were, but I had 8.5 average for both Known flights. I can't wait for the contest where we have more RVs than Pitts and Decathlons, but it should be coming.
Cheers,
Bill McLean
RV-4 slider
lower AL

Spin Experience Please

Well, I think I share Scott's concerns. I have not tried competition spins in my RV-7 yet, but have spun it upright in both directions up to four turns. As he says of his eight, the rate of rotation in my seven is what I would call 'normal' for the first turn. At the beginning of turn two, the rate basically doubles - it really winds up. So, input from Ron and Bill (Bill, I see you have replied to Eric's post - thanks!), or others who may have experience with competition spins in an RV would sure be appreciated!

As background, I have spin and competition experience in a Pitts S-2A, which was very predictable and did not accelerate the spin as the RV does, unless you made it so. As Eric points out, technique is important and differs between airplanes, I just feel some concern with the seven that was not there with the Pitts.

Thanks for any input,

Merrill

Merrill, I read Scott's comments as simply describing quirky stall/spin characteristics of his RV-8 rather than concerns regarding RV spin rotation rate. He seems to be describing stall/spin qualities that make it hard to present a believable spin entry to the judges (apparent (unaccelerated) stall, and simultaneous movement into autorotation about all 3 axes - pitch, yaw, and roll). He also describes uneven (and possibly inconsistent) rotation rate around the 1 turn mark which I assume throws off his timing of a precise 1-1/4 spin stop. Of course the 1-1/4 turn spin also involves a yaw correction, which is the reason for it having the highest 'K' difficulty factor.

Two issues are being raised here - fully developed RV spin rate, and the challenge of producing a spin entry that is believable and meets the IAC judging criteria. Regarding fully developed spin rotation rate, this is not an issue in competition, since RVs will never see more than a 1-1/2 turn spin. Up to two full turns is in the Aresti catalogue, but the RV categories - Primary, Sportsman, and maybe Intermediate will never see more than 1-1/2. Recovery for the 1-1/2 is initiated at about the 1-1/4 turn mark, so fully developed spin rotation rate (2+ turns) does not factor into competition spins.

Regarding the issue of producing a good spin entry, the main issue with RVs seems to be getting a clean stall and immediate rotation. RV wings like to fly. But there are lots of techniques to experiment with and help clean up the spin entry and rotation - slight rudder use before the stall, climbing slightly, entering slightly slower than your power off stall speed with power, using aileron either momentarily or sustained, unloading the stick slightly after the break. Not all of these may apply to any particular type of aircraft, but are ways to clean up competition spin entries and rotations. You just have to learn exactly what's required in your particular airplane. It's not necessarily as simple as stalling the airplane and kicking rudder. And that is just piloting technique. Other variables are idle RPM setting, CG location, and elevator travel. Even a metal vs. wood/composite prop can affect spin characteristics.

Again, Ron and Bill have learned to coax their airplanes into behaving well. No special education of judges or limitations needed. I disagree a bit with even the concept of educating a judge on specific aircraft qualities. Either a spin occurs or it doesn't. It either spins or spirals, or neither. It's fairly easy to separate spin from spiral in any aircraft. As long as the spin is seen to occur, the rules are clear about what must take place during the spin entry itself. There is no leeway for the characteristics of different aircraft. Pilots must learn to make the airplane perform (or appear to perform) as the judges expect to see.

sandifer said:

. No special education of judges or limitations needed. I disagree a bit with even the concept of educating a judge on specific aircraft qualities. Either a spin occurs or it doesn't. It either spins or spirals, or neither. It's fairly easy to separate spin from spiral in any aircraft. As long as the spin is seen to occur, the rules are clear about what must take place during the spin entry itself. There is no leeway for the characteristics of different aircraft. Pilots must learn to make the airplane perform (or appear to perform) as the judges expect to see.

Click to expand...

Agree 100% with Eric's comments. My home/runway is just 6 miles east of the Charlotte class B. Often I return from western destinations at 11,500 feet to clear the airspace and then spin down to 3000 feet over my field. You can learn a lot in 8500 feet of spinning!

1. The spin does accelerate after approximately one turn.
2. Some control of spin rotation speed can be had by useing opposite aileron and/or modulating rudder input.
3. After about 6 or 7 turns the engine will quit as fuel has gravitated toward the wing tips.
4. It you release the stick in an established spin it tends to stay at the full aft position!
5. Recovery with full opposite rudder and stick neutral can take up to a full turn.
6. Recovery with full opposite rudder and stick well forward of neutral is accomplished in 1/4 turn or less.
7. Following spin recovery the engine will resume operation in less than 10 seconds. The prop never stops.

As Eric said, IAC competition spins in the Sportsman category never exceed one and a half turns. Spin recovery is immediately followed by a vertical dive prior to completion of the figure. A recovery from the spin with full opposite rudder and aggressive movement of the stick forward of the neutral position will cleanly break the spin and result in the desired vertical line after the spin.

If your RV has difficulty entering a spin at the stall with full rudder you may need to help a little with aileron, climb slightly during the entry or adjust your center of gravity with the addition of ballast.

While spin characteristics of the RV may be different from other types the physics involved are constant for all aircraft. I would urge those who wish to learn more to contact their nearest IAC chapter and attend one of their practice days. I have yet to meet an IAC member who wasn't 100% interested in helping me improve my aerobatic skills.

Very good info Ron,
In my limited judging for Mini IAC a competitor would zero a spin if they used Aileron. This would show that they had not stalled and spun but instead done a spiral.

MarkW said:

In my limited judging for Mini IAC a competitor would zero a spin if they used Aileron. This would show that they had not stalled and spun but instead done a spiral.

Click to expand...

Would that be aileron "into" the spin direction, or "against" the spin direction?

The 150 Aerobat that I did my spin training in seemed to hate spinning if the ailerons were neutral. But if you cross-controlled it right at the stall point the inside wing would stall first and it would initiate the spin faster and it was easier to keep it in there for a couple of turns.

Maybe this would help with the entry? Note: I haven't spun my RV yet, so this is just speculation...

Snowflake said:

Would that be aileron "into" the spin direction, or "against" the spin direction?

The 150 Aerobat that I did my spin training in seemed to hate spinning if the ailerons were neutral. But if you cross-controlled it right at the stall point the inside wing would stall first and it would initiate the spin faster and it was easier to keep it in there for a couple of turns.

Maybe this would help with the entry? Note: I haven't spun my RV yet, so this is just speculation...

Click to expand...

That's exactly what my -8 likes.

Great tips Ron. Regarding "in" or "out" spin aileron use, both can be useful, depending on the airplane and the issue you're trying to deal with. In the Pitts, a little momentary in-spin aileron (aileron input in the same direction as the roll component of the spin) helps clean up the entry and rotation both upright and inverted. I say roll component, since with inverted spins, the yaw and roll component are in opposite directions from the pilot's perspective. I don't use out-spin aileron in the Pitts due to the flattening effect, which causes greater variations in pitch attitude and a less consistent spin rate. Consistent spin rotation rate is not among the judging criteria for spins, but it does look better, and makes the timing of the stop easier to judge. Again, all airplanes behave slightly differently and each pilot much figure out what techniques works best not only for the airplane, but for themselves as well.

MarkW said:

In my limited judging for Mini IAC a competitor would zero a spin if they used Aileron. This would show that they had not stalled and spun but instead done a spiral.

Click to expand...

In full-scale, aileron use doesn't change the fact that the airplane still properly stalls/spins, it simply further adjusts differences in lift/drag between the two wings (already caused by the spin alone) such that the character of the spin entry and/or rotation is improved. This is not considered a 'cheat' in competition. What is considered a 'cheat', is using aileron to STOP a spin. Pilots in some airplanes can actually get away with stopping the spin a few degrees short of the intended heading, and using aileron to blend in the last few degrees of rotation for an apparent precise stop on heading. Not all airplanes can effectively employ this, and if done improperly or too soon, the judges will see the aileron effect and deduct accordingly.

When I read what Ron said about using aileron I wondered if he meant into or out of. I would think out of to help with the stall and yaw like you mention.
However with an into that would be cheating the stall. Judged as a zero in scale aerobatic competition.

ailerons

I don't think the judges can see aileron input when you're at 3500 feet AGL. Since my RV naturally wants to fall off to the left when stalled upright for the stall entry, I need to lead a little right aileron and full right rudder just at the stall to make it rotate to the right. But every airplane is a little different, and it can also vary some with different amounts of fuel in the right and left tanks.
Cheers,
Bill McLean
RV-4 slider
Lower AL

MarkW said:

When I read what Ron said about using aileron I wondered if he meant into or out of. I would think out of to help with the stall and yaw like you mention.
However with an into that would be cheating the stall. Judged as a zero in scale aerobatic competition.

Click to expand...

As Bill mentioned, it would be difficult to detect if ailerons were employed upon spin entry.

IAC rules dictate that a hard zero be assessed for no autorotation in spins. Other than that, whatever controls you employ to cause that autorotation is not specified. I suppose you could stick your hand out in the air stream to induce autorotation if you please!

When I am judging I do not notice nor care what control inputs are made. When I am judging a spin I look for a clean beginning of autorotation on the entry heading, a clean stop to the autorotation on the specified heading without resorting to an aileron roll to finish the rotation, a vertical down line on the zero lift axis of the airplane following spin, and a pullout on the X or Y axis as specified.

As judges, we're taught to grade solely on what we see. So even if the competitor freely admits he ailerons the plane, if it visually meets all the criteria of a perfect spin and I can't tell that it was aileroned, I give it a 10. As I tell people, it doesn't matter what the pilot did. It only matter what the judges saw. I've seen folks with little S-1 biplanes stuff their airplanes into the top of the box to make it hard for judges to see details (and therefore flaws) in their flying. I can only downgrade errors if I see them, and the competitor always gets the benefit of the doubt, so there is some logic to that strategy.

On the other hand, I ding them quite badly on presentation...

Anyway, the most common error I've witnessed with RV competitors is forcing the plane into a spin with overly aggressive pitch inputs. Where my Pitts might not have much pitch authority near the stall, an RV does. As noted, the RV wing likes to fly and sometimes competitors get impatient. Perhaps they sense the end of the box coming up and are concerned about spacing or outs.

The stall and autorotation are supposed to begin simultaneously. If the pitch-up reaches the point where I consider the entry to be accelerated (snapped), the figure receives a hard zero.

I love the RVs for competition. Like any aircraft type, they have unique characteristics which must be understood and mastered in order to perfect the flying, but there's no doubt that the airplane is extremely capable and shows well in the box.

--Ron
IAC National Judge

Spot on!

ronrapp said:

As judges, we're taught to grade solely on what we see. So even if the competitor freely admits he ailerons the plane, if it visually meets all the criteria of a perfect spin and I can't tell that it was aileroned, I give it a 10. As I tell people, it doesn't matter what the pilot did. It only matter what the judges saw. I've seen folks with little S-1 biplanes stuff their airplanes into the top of the box to make it hard for judges to see details (and therefore flaws) in their flying. I can only downgrade errors if I see them, and the competitor always gets the benefit of the doubt, so there is some logic to that strategy.

On the other hand, I ding them quite badly on presentation...

Anyway, the most common error I've witnessed with RV competitors is forcing the plane into a spin with overly aggressive pitch inputs. Where my Pitts might not have much pitch authority near the stall, an RV does. As noted, the RV wing likes to fly and sometimes competitors get impatient. Perhaps they sense the end of the box coming up and are concerned about spacing or outs.

The stall and autorotation are supposed to begin simultaneously. If the pitch-up reaches the point where I consider the entry to be accelerated (snapped), the figure receives a hard zero.

I love the RVs for competition. Like any aircraft type, they have unique characteristics which must be understood and mastered in order to perfect the flying, but there's no doubt that the airplane is extremely capable and shows well in the box.

--Ron
IAC National Judge

Click to expand...

. Well said!

What I was trying to say...

Eric understands exactly what I was trying to say.

First off, I am not afraid of spins, actually enjoy the challenge of a competition spin. But, MY 8 in competition trims, like most 8's, is forward CG. The plane will buck and shake at the stall, full rudder will get the plane wallowing for the first 1/8 turn or so. It just doesn't like entering a spin. We had one judge that consistently "zeroed" me for my entry, not stalling and rotating at the same time. Just one of three judges but that hurts the score. I spent some time in a practice session demonstrating spins to her, including slightly accelerating the entry. With encouragement from other judges, she was able to see the "wallowing" as rotation. Is this a bad thing? I don't think so. In any competition, aerobatic or otherwise, the winner is often the team with an "unfair advantage". I am just trying to give myself an edge. ;-)

As far as the 1 1/4 goes, I think the issue, again is the forward CG. My plan (before finances stopped my competing) was to secure some weight in the baggage area to move my CG aft, hoping it would slow down or at least delay the acceleration of the spin rate. I was also going to spend time playing with ailerons during the rotation to see if I could slow it down just a bit. Yes, this all amounts to "PRACTICE, PRACTICE. PRACTICE" and learning the subtlties of your aircraft.

I can hit the 1 1/2 far more consistently because the rapid rotation rate has been established by then whereas it is just developing at the 1 - 1/4 point, making it more difficult. So,when Vickie showed up at one of our contests and sought me out to discuss RV's in competition, I lobbied for either a one or a 1 1/2 turn spin because it would help my score. Others (some RV, some not) were trying to get the spin out of Sportsman, others were trying to limit it to one turn, all in the name of safety. Me?, I was just trying to make the spin easier for ME so I could spend more time practicing my lines and the more difficult figures like the loop!

Scott A. Jordan

N733JJ said:

Eric understands exactly what I was trying to say.

First off, I am not afraid of spins, actually enjoy the challenge of a competition spin. But, MY 8 in competition trims, like most 8's, is forward CG. The plane will buck and shake at the stall, full rudder will get the plane wallowing for the first 1/8 turn or so. It just doesn't like entering a spin. We had one judge that consistently "zeroed" me for my entry, not stalling and rotating at the same time. Just one of three judges but that hurts the score. I spent some time in a practice session demonstrating spins to her, including slightly accelerating the entry. With encouragement from other judges, she was able to see the "wallowing" as rotation. Is this a bad thing? I don't think so. In any competition, aerobatic or otherwise, the winner is often the team with an "unfair advantage". I am just trying to give myself an edge. ;-)

As far as the 1 1/4 goes, I think the issue, again is the forward CG. My plan (before finances stopped my competing) was to secure some weight in the baggage area to move my CG aft, hoping it would slow down or at least delay the acceleration of the spin rate. I was also going to spend time playing with ailerons during the rotation to see if I could slow it down just a bit. Yes, this all amounts to "PRACTICE, PRACTICE. PRACTICE" and learning the subtlties of your aircraft.

I can hit the 1 1/2 far more consistently because the rapid rotation rate has been established by then whereas it is just developing at the 1 - 1/4 point, making it more difficult. So,when Vickie showed up at one of our contests and sought me out to discuss RV's in competition, I lobbied for either a one or a 1 1/2 turn spin because it would help my score. Others (some RV, some not) were trying to get the spin out of Sportsman, others were trying to limit it to one turn, all in the name of safety. Me?, I was just trying to make the spin easier for ME so I could spend more time practicing my lines and the more difficult figures like the loop!

Scott A. Jordan

Click to expand...

Bill has a 1.5 inverted spin in his free routine! Pretty impressive!

competition

Scott,
I looked up your scores at the Green Mountain Contest in 2009, and they were very good, except in your first sequence for your first Goldfish and loop. On your second sequence you averaged an 8.4 for the Goldfish and a 8.1 for the loop. Those are great marks. Of course taking home the trophies and goodies requires consistent high scores, which improves with practice (I'm told). Hope to see you back in the competition soon. By the way Mitch, that's a 1 turn inverted spin, otherwise, I would have zeroed all the figures that followed.
Bill McLean
RV-4 slider
lower AL

Didn't know scores were that easy to find.

Thanks, Bill. Green Mountain is a. Fun contest though I don't recall the speciics of that contest, I did have good flights and less good flights. you didn't mention my spin scores at that contest, as I recall, they were generally good once the judges got used to the appearance of the RV. Yes, judges do need to get used to the profiles of specific aircraft types, that is one reasons the S-2C has a flatter belly then earlier models, it presents/scores better then the "pot bellied" Pitts!

Anyway, if you dig around my other contests you will find the Hammer that I zeroed (KFJ?). I kicked early, rotated, yawed and fell on my back a bit. I did what I needed to do to get the airplane pointed down (Thank you, Bill Finangan) but was 90 off heading. Oh, well. I was told by those son the ground that I was headed to an inverted spin. Which brings me to your inverted spin, how do you do it? I have tried many times, many ways including recreating my botched hammer (the plane just continues to "wallow", eventually points itself down). I started by trying inverted stalls, my plane is "Ercoupe" like, full forward stick, throttle idle, it mushers down at 1000'/min indicating 100kts. I have not tried it with an aft cg. I have tried inverted spins from an Immelmann, hammerhead... No luck. Not even a stall that will remain stalled. I suspect an aft cg would help, need to find a way to secure a weight in the baggage area.

Your thoughts, experiences?

Scott A Jordan

Interesting read. I am too old to do this stuff but it is interesting.

My spin experience goes back 50+ years ago in T-34's, T-28's and a C-150 I once owned. They all had their characteristics and different technique.

Training, training is so important, almost bought the farm in the 150 doing the CFI spin demo ride. The CFI observer was very inexperienced and did not want to show how to do it, so I just stalled it, left rudder and off it dropped and spun several turns. For lack of knowledge re the 150, used the T-28 technique to recover, stop the rotation and popped the yoke forward. The 150 went into a vertical dive and through the red line in about 4 seconds. It was a very gentle recovery loosing much altitude. I asked the observing CFI if he'd like to see another one and he said no, that will do. He was white with fear, poor kid.

No competition stuff for me, but I did learn how to spin that 150