On Friday, January 19, 2018 at 8:47:39 PM UTC-5, Burt Compton - Marfa Gliders, west Texas wrote:
On Monday, January 15, 2018 at 6:57:46 PM UTC-6, wrote:
Who has done a loop in a standard cirrus? Any comments or hints. Currently getting some acro training with the goal of looping my cirrus.


Please get acro training in a two seat sailplane in an ASK-21. Acro training in an airplane such as a Citabria has the advantage of adding engine power at the top of the loop. In a sailplane you might get bit slow at that point.

Ask me how I know. Decades ago, I had acro training (spins, rolls, "round" loops and when you mess up, "dishing out" / "Split-S" recoveries) in a Citabria airplane from an acro competitor / CFI. Then in my Blanik I tried to make a "round" loop. At the top I got very slow and mushed down inverted for a few seconds. An acro CFI in Germany told me later that I could have entered an inverted spin. He suggested smooth full stick back at the top of the loop to make sure it gets all the way around past inverted without getting too slow.

Nor do you want to get too fast on the backside of the loop.
Your Standard Cirrus Vne is only 119 knots indicated at sea level, relatively slow compared to modern sailplanes. Entry speed for a loop in your Standard Cirrus per the flight manual is 97 knots.

Vne in my ASK-21 is 151 knots at sea level. 121 knots at 15,000' MSL. Entry speed for solo loop is 84 knots.
Check your flight manual to learn the "real" True Air Speed (TAS vs. IAS) at altitude as a sailplane will accelerate quickly nose down around the backside of the loop compared to a relatively draggy airplane. Know your maximum speed for deploying airbrakes / dive brakes.
Be real smooth on the controls (in any phase of flight) . . . your Cirrus sailplane is not a Pitts Special.

Know that your Va Maneuvering speed is lower when you are flying at a lower weight than max gross.
That might not seem intuitive but that's why Va speed is not usually marked on your airspeed indicator.
Va varies with aircraft weight. The flight manual Va, along with other limitations including load factor, is at your maximum allowable gross weight. By the way, "a" is for acceleration. Read up on Va.

Beware of flutter which can destroy an aircraft. Flight control connections, hinges, etc. need to be lubricated and as snug as they were from the factory. Consult your Maintenance Manual for how much control surface looseness or "jiggle" is allowed with someone holding the stick hard/still and then check the proper degrees of up/down or left/right control deflection. That would be on your FAA Type Certificate Data Sheet (TCDS) available at faa.gov

Adjust the airbrake pushrod tension so they do not pop full out when flying fast into the loop.
Keep your left hand on that blue airbrake handle to hold it in, then be ready to pull it if you get too fast on the backside of the loop.

Get a current Weight & Balance accomplished.
Install a calibrated G-meter.
My 1972 Standard Cirrus at Marfa, Texas, is fairly low time but I do not feel the need to loop it as "soaring" is what it does so well. If I want to do acro and not have to take a lot of tows, I get into a Citabria airplane.

My ASK-21 that I bought new is definitely loop capable. For resale value, I purposely imported it as "acro" from the Schleicher factory and it is FAA certificated as "Acrobatic." The factory installed calibrated G-meters with plus and minus red lines (+6.5 and - 4G at Va, not Vne), crotch straps for inverted flight and the structural red rings for your parachute static line. Yes, acro in the ASK-21 is fun. It also soars really well.

I do not consider myself a current acro instructor. My thoughts above are not ground school in acro nor for preparing your sailplane. I strongly recommend you contact a CFIG that is proficient in sailplane acrobatics. (By the way, in Germany, an "Acro" CFI is a separate CFI advanced rating.)

So, do what you like (up high) but my suggestion is to get dual instruction from the 4 time sailplane aerobatic champion Jason Stephens at Arizona Soaring, south of Phoenix. (See his advert on the inside front cover of your SOARING magazine.) Reading a book or my comments is not enough to be proficient.

Jason Stephens is the best and that's who I would get dual instruction from if I decided to get back into sailplane acro.

Burt Compton, CFI airplane & glider / FAA Designated Pilot Examiner
Marfa Gliders Soaring Center, southwest Texas
www.flygliders.com

I agree with everything Burt says but would add that there is a meaningful difference between acro in a '21 or Grob and most single seaters. Things get out of hand slower in the 2 seaters. One should be pretty good in deuce before doing in single.
UH