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RV-7 aerobatic practice

Darren S

Well Known Member
Hi all,

This is my first attempt at videoing one of my aerobatic practice sessions. I wore a GoPro camera that was strapped to my forehead. In hindsight I should have hard mounted it as it is kind of shaky.

I thought I'd share it none the less. I plan to enter a contest this August in the "Primary" class so this is a few run throughs of that sequence.

What other plane can cruise at 160 knots at 65%, burn 9.2 GPH, carry 100 lbs of payload, climb at 1400 fpm is Aerobatic and look so good doing it ?..............none.

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

Darren
 
Hey Darren,

Great video. Thanks for sharing and showing that RVs can fly the lower category sequences no sweat. I think you'll have a great time at the contest.

Have you had the opportunity to receive any ground critiquing? I know IACer's are few and far between in Canada. Hope you don't mind a few honestly constructive comments on the Primary sequence based on things I've learned over the last few years at the contests I've flown, Primary through Intermediate. I think you'll do a great job with it.

First, don't forget to wing wag before starting! (3 wags). Practice this every time, and consider it your first maneuver. Get your head in the game right away and do them assertively (at least 45 degrees) and with precision. Get the judges' attention and show them right away that you know what you're doing! Don't get called for a "weak" wing wag. You'll take a small point deduction if you don't do them or if the judges can't see them. Always bank toward the judges doing wing-wags and use them to help get a good view of your position in the box before pulling for the first figure.

45 lines up and down are a crapshoot as far as how judges grade them, so just get some critiquing. Do you have inverted systems? If not, then you're doing very well as is. If so, then you're still doing well, but you can definitely take more advantage of the inverted systems. :)

Figure 1, 45 upline - At the top of the upline, I'd push over more decisively to your level line. Just presents the separate lines better. You're floating for a very long time slowing down for the spin. Could cause problems with box position or cause you to go out. Cap off the 45 line at a slower speed by drawing a longer line or entering slower. Unless you need it for box position, you should draw a short level line before entering the spin. Two ways to cap off the 45 - select an airspeed to push over while simultaneously pulling the power to idle, or wait until your are a few MPH above stall speed on your 45 upline, leave in full power and pushover to level flight. The second method should leave you slightly slower than your 1G power-off stall speed. Then just pull the power off, which will cause the plane to immediately stall. Add full rudder immediately followed by full aft stick as soon as it stalls and you're spinning. This method allows very precise control of your line before the spin.

Figure 2, Spin - It's OK to climb very slightly into your spin entry. It helps you slow down slightly faster, the judges won't see it, and it can help with a cleaner entry. But definitely be careful to avoid any sinking. Your first entry was the cleanest. You didn't force it into the spin, which is good. Always make sure it stalls FIRST before applying rudder, but be spring-loaded to apply it. Ideally, you want simultaneous movement in all three axes - nose drop, yaw, and roll. Any deviation could get you downgraded for "forced entry". Hold a slight amount of rudder in the direction you want to spin to ensure it breaks in the direction you intend without wallowing for a second the wrong way. Looks like you don't have trouble coming out on heading, but you are positive on your downline after the spin. It takes a pretty healthy pushover to set a vertical downline after stopping a 1-turn spin. If you don't have inverted systems, you may be hesitant to push over. Briefly look at your wingtip as the spin stops and you pushover to check your attitude. I know it goes against the grain when you're pointing straight down and accelerating fast.

Figure 3, Half Cuban - You maintained your heading well during the looping and rolling portions, but the top of the loop appears it was pinched (not round). Need to float the top just as if you were doing a round loop without the roll. It appears your 45 inverted line is a little shallow, and that you're rolling as soon as you set your pitch. You might be doing this due to lack of inverted systems, but be aware the judges may take points off for "no line before the roll". Same thing with your line after. Though if you're drawing a very short line before, you'll want to draw a short line after as well. In general, you should spend half again as long on the line before the roll to keep your line lengths equal, since your speed is building. For example - do a quick 3-count before the roll, and a quick 2-count after the roll before pulling level.

Figure 4, Loop - This is the hardest one to self-critique. You really need a lot of help from the ground to get a feel for what it takes to get it truly round. But I can tell by your pitch rate throughout the loop, that you're likely pinching it a good bit (looks like a cursive lower-case "L"). You need to increase your pull slightly past vertical up, and then relax it a good bit about 30 degrees before inverted level in the second quarter of the loop. Then be patient floating over the top before steadily increasing your pull from about 30 degrees nose down. Think about pitch rate. For example, if you enter and exit the loop at 160 and you're at 80 over the top, then your pitch rate at the top should be half that of your rate at the bottom if you're to have any chance at making it round. Forget wind correction for now. Looks like your pitch rate starting, and especially during the last quarter is lower than the pitch rate at the top. Again, takes a good bit of help from the ground, not to mention practice. :)

Figure 5, 180 Turn - Pretty straightforward, couldn't see any obvious issues. Just make sure you set your bank angle (min. 60 degrees) BEFORE letting the nose move into the turn. The reverse for stopping it - stop the turn with elevator and opposite rudder, hold the nose on a point before rolling level.

Figure 6, Roll - You're doing it pretty well, especially if you're cheating slightly due to lack of inverted systems. Don't see any heading issues. Looks like you're ending the roll slightly nose low, but then that could be part of the cheat. But it does appear that you might be subconsciously relaxing aileron pressure passing through inverted. It appears the roll rate on most of them slows down around the inverted stage. Just make sure you've got full deflection. The judges are looking for constant roll rate, among other things. You'll learn there are other things to consider in controlling roll rate, such as the fact that the roll rate will increase a little as you add top rudder during the last quarter of the roll, requiring a slight reduction in aileron to keep the roll rate constant.

Again, I think you're doing a great job and will do well. Hope you take my comments purely constructively. NOBODY has a chance at doing well at a contest without experienced help from the ground. You could probably tighten up most of this on practice day, which everybody will be glad to help you with. Good luck, don't take this contest stuff too seriously, and most importantly HAVE FUN!
 
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Hi Eric,

Thanks for the excellent post and your comments. I am a newbie to this aerobatics stuff and I will readily take all the help I can get. You obviously know what you are talking about and have a keen eye to pick up on some of my errors. Thanks for point them out and it will give me some things to work on next time out.

My plane doesn't have inverted oil and fuel so I guess it would be wise to minimize the negative G stuff. My instructor and I are planning to head up to the actual contest site where he will give me some ground critiquing. He said the same thing that without it I will never be able to feel my errors.

I read your post a few times and here are the things I am going to try next time:

- push more aggressively at the top of my 45 degree climb and bleed off more speed so that my spin entry isn't dragged out so long.

- carry some rudder into the spin to make sure it rotates in the direction I want.

- push more forward stick at the bottom of the spin to establish a downline.

- float more over the top of the 1/2 Cuban and then establish a definitive 45 inverted downline for say 3 seconds. Roll and extend the second half for 2 seconds.

- don't pinch the top of the loop. Pull more at beginning and float over the top.

- keep my roll rate consistent throughout.

Last thing, can you clarify on the wing wag. I've never heard of it. Do I do this outside of the box prior to entry for the first manoeuvre ? Is it along the flight line or 90 degrees to the flight line ?

Thanks again for taking the time to watch and comment.

Darren
 
Darren
Thanks for posting the video. I have been playing with my -7 and have thought about going to a contest.
Have you got a copy of the program you would fly at a contest? I looked online and have not had any luck finding one.
I can't tell from the video, did you stay in the competition box for your practice?
I have no experience other than fun sloppy acro but found Alan Cassidy's book, Better Aerobatics, an informative read.
Thanks for posting
Dave
 
float more over the top of the 1/2 Cuban and then establish a definitive 45 inverted downline for say 3 seconds. Roll and extend the second half for 2 seconds.

3 full seconds in an RV before the roll and 2 full seconds after on a 45 line with power will get you going pretty fast on the downline. It can be manageable, but you may need to pull power a little. The actual time spent on each line is not critical. What is critical is that you draw a perceptible line before and after the roll, and that your line lengths are equal before and after. As long as the judges can see that you drew a line (not rolling immediately as the 45 is set), then that's the only judging criteria. From there, just time your lines so that they look equal in length from the ground. Here again, ground critiquing. Different airplanes will spend different lengths of time on the line. RV's due to their clean nature will spend a shorter time than many other planes. Slowly increase the time you spend on the line to figure out a method of timing the lines that you're comfortable with and stays within the margins of operating limitations. You just might end up counting using shorter seconds. :)

Last thing, can you clarify on the wing wag. I've never heard of it. Do I do this outside of the box prior to entry for the first manoeuvre ? Is it along the flight line or 90 degrees to the flight line?

This is the way you tell the judges you're about to start the sequence so they can focus on your actions immediately following. Think of your box entry as a traffic pattern - fly a downwind, base, and final into the box. You must fly your wing wags on "final". Whether you're inside the box or not when you wing wag doesn't matter, but to use them to help you see your box position would require at least the last one to be done inside the box. On "final", simply establish a quick 45 degree bank, and back to level. That's one wing wag. Remember you must use opposite rudder and unload the stick very slightly to stay on heading and keep from turning during the bank. You must do three wing wags before starting your first figure. You don't necessarily have to do them all at once. If you don't like your box position during your first one or two wing wags, you can delay the last one for a better look at your box position before pulling for the first figure. It's customary to do two wing wags after you've finished the sequence, though you won't be penalized if you don't do them. Not true of the starting wing wags.


Have you got a copy of the program you would fly at a contest? I looked online and have not had any luck finding one.

You can take a look at the 2011 "Known" sequences here. In Primary, you fly the Known only (a couple times). The Sportsman category has the option of flying a "Freestyle" sequence, but very few folks bother designing a Free, and simply fly the Known for all their flights. Starting with Intermediate and through Unlimited, it gets more interesting in that you must fly three unique flights - the Known, which is published at the beginning of each year by IAC, and is the sequence everyone flies for their first flight at all contests during that year. Second flight is the Freestyle of your own (or borrowed) design. The third flight is the "Unknown", which is a sequence nobody has ever seen that is handed to you the day before you must fly it. You may not practice it (except in your head and on the ground) before flying it. This is where things get interesting (and fun), and is the real separator.

http://members.iac.org/knowns/knowns2011/
 
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Hey Dave,

Hopefully you can find the sequence to fly. Eric obviously knows what he is talking about so follow his lead. I have a link I will send you later if you need. It's what I have to fly this year. Not sure if it is different between Canada and the US. Likely not.

Aerobatics has opened up a whole new dimension to flying. In a rookie too but those crosswind landings aren't so scary as I'm getting use to stomping on the rudder and making the plane obey me, not the other way around.

It gives me a purpose to my flying and a goal to shoot for. At first my head would feel a little woozy after half an hour, but now I don't notice it so much. A physical exercise program helps too, I think.

I say go for the contest. Doing the manoeuvres is challenging, but doing them where you are suppose to is much more challenging. My friend up here in Canada just told me that if it were easy it wouldn't be as fun:)

Darren
 
My plane doesn't have inverted oil and fuel so I guess it would be wise to minimize the negative G stuff.

Darren, One more thing - flying the brief negative lines and pushes required of the Primary sequence won't hurt anything if you don't have inverted systems. Check your oil levels and get a feel for how much oil you may be throwing out so that you don't lose a critical amount during a long practice session. Different amounts of oil in the sump may affect how much you actually throw out of the breather. Try to figure out what works best. Oil loss during a single Primary sequence should be negligible no matter what you do. And depending on your setup, you might need to clean a little oil off the belly. Hope to see more videos.

See Ron Schreck's article here. This is a great solution for Primary/Sportsman level flying that doesn't involve full inverted systems. But not applicable unless you have fuel injection. You might consider installing an oil separator only.

http://iac19.org/images/DAF_APRIL_10.pdf
 
Join IAC

For those interested in aerobatics I would strongly recommend joining the (International Aerobatic Club (IAC): http://www.iac.org/ Just try it for a year, and you'll have a source for the various IAC chapters locations, flight instruction, how to do the maneuvers, location of contests, etc. etc. etc. The best part about IAC is their first priority is SAFETY, even before all the fun you'll have. Unfortunately, very few RVs have competed over the years, but we definitely can. I made a 9 minute DVD of this years' sportsman routine, but don't have the computer, skills, software, internet connects, (very old), to post it, but if anyone is interested, I can make copies the old fashion way with a DVD recorder and mail out. Send me a PM with a mailing address.

Bill McLean
RV-4 Slider with modified wing tips.
 
Hi Eric,

Thanks for the advice on the oil level. I find that 5 quarts is a level that works for me. I put in a quart one day and brought the level up to 6. After the practice session there was literally oil dripping off of the tail wheel ! It eventually stabilized at 5 quarts and this is where I keep it. The IO-360 only burns about a quart every 35 hours so she is pretty good.

The weather up here in Southern Alberta is crappy again so I'm grounded, but hopefully this weekend I can get out and put into practice all this great advice I got.

I didn't think my lousy video would be such a good teaching tool and I'm amazed at how much information you can glean from it. Next time I will try and keep it shorter, mount the camera better and start off with 3 wing wags to show the start of my sequence.

Thanks again,

Darren
 
Darren, have you considered what will happen if you lose oil pressure, even momentarily while inverted? With a "normal" non counterweighted C/S prop it goes to fine pitch, and possibly an overspeed. I have inverted oil in my 7 and even with that it will momentarily lose pressure occasionally while transitioning to negative, fortunately I have an aerobatic prop so it just loses RPM for a bit. Just something to think about before extending those downlines on your Cubans.

I'm glad to see someone interested in competing with an RV, If I had more time I'd like to do it too. Keep us posted.

Good Luck!

Neil
 
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