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  #11  
Old 12-26-2018, 09:32 PM
sandifer sandifer is offline
 
Join Date: Jan 2007
Location: NC
Posts: 667
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Quote:
Originally Posted by spatsch View Post
Not quit sure why you say that. Only made one contest this year but my spin average was 8.8 in both flights and I have no weight in my tail. Never had an issue with spin entry.
Unfortunately, misinformation about the suitability of RVs for competition acro has largely come from those within the RV community itself who have little or no experience with it. Fortunately folks like you, Ron, Bill, Jerry, and a modest growing number of others produce results that speak for themselves.

Last edited by sandifer : 12-26-2018 at 09:34 PM.
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  #12  
Old 12-27-2018, 07:22 AM
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ronschreck ronschreck is offline
 
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Location: Gilbert, AZ
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Quote:
Originally Posted by f14av8r View Post
I dislike the inclusion of snap rolls in the intermediate sequence. RV type aircraft do not snap well or easily. And, frankly, it's just **** hard on the airplane. I love competing in my airplane but I don't want to destroy it either. Snaps should be for advanced and above. That would encourage more proficient sportsman category participants to move up a level. I will never move up to Intermediate if I have to snap roll my airplane - period.


Best regards,
Randy
Randy,

I would hate to see you stuck in Sportsman for the rest of your life just because you won't do snaps. Snaps CAN be hard on the airplane if done improperly which means done at too high airspeed. I find the sweet spot for snaps is 100-110 knots which is well below the 122 knot maneuvering speed. I never see more that 3.5 Gs on my snaps and with the CG about 1.25 inches forward of the aft aerobatic CG limit the snaps seem to score well and feel very comfortable. Van has weighed in on snaps in his article in the August 2016 Sport Aviation magazine:


"SNAP ROLL MANEUVERS
RVs are capable of performing snap rolls, but
these tend to be less crisp and of a lower roll
rate than many other aerobatic aircraft. Also,
I found that when trying to improve their
crispness by performing them at near
maneuvering speed limits, more than 4g was
experienced. Since this was a higher level
than I was comfortable with, I saw this as
one more deterrent to competition flying. I
did not include snaps in my air show routines
other than when done at low speeds,
such as at the tops of loops. I feel safe saying
that regardless of pilot skills, RVs cannot
perform crisp snap rolls like those routinely
exhibited by new aerobatic designs. That
said, some competition aerobatic pilots have
shown that RVs can do snap rolls satisfactorily
for requirements of the Intermediate
class."


(Note: That last sentence was referring to Bill McLean and myself.)

Randy, I have been doing snaps for years and have seen no damage attributable to that activity. I think you will see that snaps in the Intermediate category are such that they need not be performed at high speed. The only snaps allowed are on 45-degree up lines, level lines and avalanches. Learning snaps can be frustrating but once mastered they can be fun to perform and do no harm to the RV. Give 'em a try!

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RV-8, "Miss Izzy", 2250 Hours- Sold
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  #13  
Old 12-27-2018, 08:54 AM
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f14av8r f14av8r is offline
 
Join Date: Apr 2012
Location: Tampa (Wimauma actually)
Posts: 451
Default Snap Rolls

Hi Ron,
You're right, as usual. I think my problem with not getting a consistently repeatable snap roll is that my CG isn't far enough aft. I've been working on that. I need one of your lead shot tanks!
Thanks!
Randy
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RV-4 N212CS (sold)
RV-8 N184RK (sold)
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  #14  
Old 12-27-2018, 09:34 AM
sandifer sandifer is offline
 
Join Date: Jan 2007
Location: NC
Posts: 667
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Quote:
Originally Posted by f14av8r View Post
I think my problem with not getting a consistently repeatable snap roll is that my CG isn't far enough aft.
Randy, have you had quality coaching/critiquing on snap technique from someone truly able to dispense it? That can go a long way. Really good, repeatable snaps are a high art form and take a whole lot of work. Unless you've done a million of them, really studied, analyzed and experimented with technique down to the tiny fraction of a second differences in timing the multiple inputs, and made them automatic without thinking about them, there is likely a good bit of room for technique improvement. I say this from watching, judging, and flying a million competition snaps. Snaps are amazingly responsive to extremely small variations in timing and technique. Not at all the simple yank and stomp maneuver that lots of pilots think of them as. No two pilots snap an airplane exactly the same. They are like pilot fingerprints. At a certain point, lots of folks can do rolls, loops, lines, hammers, and spins nearly equally well. To me, the differentiator and individual style and skill is in the snaps. It's one of the most interesting things about watching competition flights.

Last edited by sandifer : 12-27-2018 at 09:38 AM.
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  #15  
Old 12-27-2018, 09:59 AM
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RV8Squaz RV8Squaz is offline
 
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Location: Senoia, Georgia
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Hello everyone! Sorry I?m late to the party here. Christmas, family, and work prevented me from joining this thread sooner. Everything I was going to say has already been said by others. I will just add my personal experience.

I wholeheartedly agree with Eric, Ron and Oliver concerning spins and snaps. Done properly, I do not feel that a snap stresses the airplane any more than a slightly accelerated spin. I?m moving up to Intermediate this season and plan on getting proficient in snaps and rolling turns. While I have yet to do snaps and rollers in competition, I have practiced the snaps a bit since September. But I have only experimented with speeds below 90 knots. I have yet to do them in the 100-110 knot range that Ron suggests as the sweet spot. Even at speeds below 90, I feel that I?ve been able to execute some really sweet snaps. Time will tell when I do them in front of a judge, but I can tell it just feels nice, kind of like a good golf swing or ?swish? with a basketball. I love doing them!. The key with doing snaps on other than an Avalanche will be to monitor your energy and practice getting your energy where you want it. If you?re too fast, take a break and try again. The only time I have felt funny about the stress on the airplane has been when the airplane popped out of the snap prematurely in an effort to accelerate the snap. It?s only then, when I felt some side loading on the plane. Again, these were done at speeds well below maneuvering speed.

Regarding the spin, I view this as a basic, essential aerobatic maneuver. It and it?s variations should be a requirement of any basic aerobatic course. A basic aerobatic course should also include stalls in all attitudes and at various speeds, and unusual attitude recovery training. The spin, being a basic essential maneuver, should be included in Primary and Sportsman sequences. Building blocks like Eric said. It was for this reason that the board decided on retaining snaps in Intermediate. Is it difficult to score well? Sure it is. But a lot of figures are difficult to score well, including the dreaded loop and my nemesis, the Cuban 8! But with practice and diligence, the spin can be flown rather successfully. One should not be intimidated by spins if considering doing aerobatics, much less competition aerobatics. If intimidated by spins, one should get the appropriate training and get proficient.

In any case, I?m really looking forward to the 2019 season. I?m really excited about the Intermediate Known and look forward to burning a lot of AVGAS in an effort to perfect it. So what?s the maneuver I feel that is going to give me the most trouble? The roller of course! In addition, the full roll after the half loop up in Figure 5. may pose a challenge. It takes a lot pot stirring and foot dancing to make low speed roll in an RV look good, but it can be done!
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  #16  
Old 12-27-2018, 02:45 PM
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WillyEyeBall WillyEyeBall is offline
 
Join Date: Jan 2007
Location: Daleville, AL
Posts: 354
Exclamation snap rolls RVs

When I first tried to snap roll my modified RV-4, I couldn?t get it to snap using the stick pull force and rudder input I had used in a S2-B Pitts and a CAP 10. I had told Ron that the -4 just didn?t have enough rudder. Ron had been routinely snapping his RV-8, but the rudder is bigger with a horn. I finally got my -4 to snap at 100 knots by jerking the stick with both hands and stomping the left rudder. What an ugly figure and unacceptable technique. The 2017 Known for Intermediate had a ? snap on an up 45 line of a 31 K figure, so I eventually after much practice and coaching was able average about a 6 score in three contests for this figure. Going through the IAC archives of unknown sequences to learn all the different figures and snap rolls at the Intermediate level, I tried UNK-320 from 2016. The ? snap in figure 3 was on an up 45 line following a push humpty with a ? roll on the down line. At the top of the humpty I pulled the throttle to idle and stayed there about 3/4 through the box to bleed off the speed before the snap roll. After the sequence, I checked my G meter in my GT-50, and it was significantly over the RV positive G limits. That really got my attention, and I checked to make sure the wings and tail were still attached. The mathematic equation to determine the number of Gs pulled with a snap roll is the square root of the air speed divided by the stall speed. For example, at 100 knots with a stall speed of 50 knots, the calculated Gs would be 4. (AS/Stall speed) ^2.
For a better understanding of the Gs, initiation and recovery of the snap rolls for my aircraft, I began a series of test flights recording Gs and AS. I?ll post the data and graphs on Ron?s RV yahoo website for those interested, with some other issues of concerns. As Eric and others have mentioned, every airplane and pilot techniques are a little different.
Bill McLean
RV-4 slider
Lower AL
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  #17  
Old 12-29-2018, 08:43 PM
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ronschreck ronschreck is offline
 
Join Date: Mar 2006
Location: Gilbert, AZ
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Default It's official....

The IAC Board met via teleconference this evening and voted unanimously to accept the Known sequences as revised by the Known Sequence Committee.
The sequences as shown in post #1 of this thread are the official Known sequences for 2019. Start practicing!
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  #18  
Old 12-30-2018, 12:37 PM
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RV8Squaz RV8Squaz is offline
 
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That?s fantastic! The Intermediate looks like a great sequence. I?m looking forward to flying it. I will need some serious practice on a couple individual figures first, the snap and roller of course. Thanks for letting us know Ron.
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  #19  
Old 01-15-2019, 06:37 PM
1flyingyogi 1flyingyogi is offline
 
Join Date: Dec 2015
Location: Long Beach, CA
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Thanks Ron! It looks like a fun sequence. Can't wait to try it out this weekend! I kinda like the reverse wedge better (more fun), but I understand that it's more difficult without inverted systems - although I don't have any problems with mine. I just want to keep the negative stuff to 3 seconds or less in duration b/c I'm worried about oil starvation for the engine. Fuel-wise, no problem.

I totally agree with Bill on the snaps. I've recently got some dual time in a Pitts S2B and done about half a dozen of them, but cannot seem to do a decent one in my -4. I just can't get it to break cleanly no matter how hard/ briskly I pull on the stick. I'm sure it's technique, and I haven't figure it out yet. Maybe I can get some input from you guys. I know snaps are not in the Sportsman sequence, but I like to learn new stuff and just have fun (besides flying competition sequences).
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Last edited by 1flyingyogi : 01-15-2019 at 10:56 PM.
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  #20  
Old 01-16-2019, 06:02 AM
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ronschreck ronschreck is offline
 
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Location: Gilbert, AZ
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Quote:
Originally Posted by 1flyingyogi View Post
I totally agree with Bill on the snaps. I've recently got some dual time in a Pitts S2B and done about half a dozen of them, but cannot seem to do a decent one in my -4. I just can't get it to break cleanly no matter how hard/ briskly I pull on the stick. I'm sure it's technique, and I haven't figure it out yet. Maybe I can get some input from you guys. I know snaps are not in the Sportsman sequence, but I like to learn new stuff and just have fun (besides flying competition sequences).
Well, look at you! One contest in Primary and you are already practicing Intermediate figures. I'm going to keep my eye on you!

Your -4 is a different beast than my -8 so what works for me may be different in subtle ways. Generally speaking, a snap roll works when one wing is stalled just when the yaw motion is introduced. The sweet spot for my -8 is 100-110 knots upon entry. I suspect it might be lower for the -4 and maybe Bill McLean can chime in here. Snaps work best at a high power setting with plenty of prop wash over the tail so it would be best to slow slightly below your ideal entry speed, add full power and initiate the snap as you get to entry speed. Apply rapid aft elevator to pitch up about 10 to 15 degrees. You should feel about 3.5 Gs in this pitch up. (Full aft stick is NOT required.) Add rudder just as you add back stick. Full rudder position should be reached at the same time the Gs peak at 3.5. This is the point where one wing stalls and the other at high alpha induces a rapid roll into the stalled wing. As soon as this happens you should release the back stick pressure as you don't want both wings to stall. It's OK to add just a bit of aileron into the snap as well. To recover, lead the stop point and apply full opposite rudder as you jab the control stick slightly forward of neutral. The point where you lead the stop point will vary with aircraft so that will come with practice.
More than any other maneuver, the snap procedure is very dependent upon aircraft type, trim, speed and pilot inputs. You may do a hundred before you find the right combination. You will know when you find it. There is no doubt when the inside wing stalls and rapid rotation occurs. You will feel it and hear it and the RV grin is evidence that it really happened!
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IAC National Judge
RV-8, "Miss Izzy", 2250 Hours- Sold
My Aerobatic Video
My Formation Video
CAF B-25 - Airbase Arizona
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Last edited by ronschreck : 01-17-2019 at 05:07 AM. Reason: correct typo
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