Unlimited Aerobatics

Some time ago I wrote about the aerobatic competition categories, as they are in Australia, and the key changes from lower to the next.  I stopped at Advanced, as that was where I was then.   It was early days Advanced also, now I'm in a similar position with Unlimited.   Probably presumptious of me to write anything with any credence!   But, then it is the person starting out and feeling there way that crave information and may glean something here they can apply.  The experienced Unlimited pilot doesn't have to agree with my observations, and would have discovered his/her own methods.   I'd love to hear from some of them and milk their experience, it would save me many dead ends I am sure.   I joked to Paul at the Boot Camp, that once you get to ADV/UNL level, all assistance stops!

What do you need to learn going from Advanced to Unlimited?  The key new figures are:  Negative flicks/snaps, tailslides, and inside/outside rollers.   Not much huh?   Excepte that all the rolls, all the flicks, can occur on all the lines, i.e. up, down, 45's.   And every roller in the book seems fair game.

First the rollers:    You can practice these anytime, at any level.   Have a crack.  They shouldn't hurt and practice plus technique will make them better.  Technique?   Lead with rudder and get the first 20 degrees or so cheap.   Keep the nose above the horizon, don't let it slide down as it will be very hard to recover.   The nose actually bobs up and down in a rhythm when you get it right, not stay on, and roll, around the horizon.  Sacrilege you say?  Well, each to their own, but I challenge you to fly a 180 one roll roller without lifting the nose.   Done nicely you won't be running out of rudder.

Negative Flicks:   Like diving off the high board for the first time, you just have to do it at some point.   Start gentle from an inverted  45 up line.   Get the 'hang' of it, as at first it feels strange hanging in the straps looking out as you get flung around!   Cool!   Then try from level inverted at low speed.   Try different feet - I like left footers, but others like right.   To me they go in easier with left foot.  This isn't ideal, as you will get more diversion from the flight path and larger cone angle with left foot (like for right foot upright snaps).  And, as for 3/4 down snaps in Advanced, you need 3/4 up and down, with either foot, in Unlimited!   My current project is right foot neg snaps, I've got them biting, but the exits are untidy.   The picture just looks different.

It may be my aircraft, but I seem to get more 'feel' in the neg snaps.   You pitch, then feed in rudder, and at a point you feel it break into autorotation, then you can unload and it accelerates.   The pos snaps seem more graunchy in comparison.   Possibly my wimpy push prevents 'burying it' as I tend to do for pos snaps.

Tailslides:  Mmmmm.   Hard for me to give advice, as mine are terribly unreliable still.    Cheat is all I can say, and cop the downgrade.   It sounds obvious, but a well set, stable vertical is very important, then try and centralise rudders (hard to do), and watch your tell-tail for the slide, then stick forward or back, as required.   Aggressive (as in ALL) rudder on the low wing side can sometimes salvage a poorly set vertical.

And what to do when it all goes wrong when flicking or sliding?    Power - IDLE, Controls - CENTRALISE (both hands), and wait for god's g to take over, then recover.   This will only work if you have enough altitude, obviously.  Don't say I didn't tell you so, Captain.

So that's it.  Go out and cut sick.  Once all that is working to some degree, you need to try it in a sequence, in a box, for judges.    That's where some extra techniques to make life easier may come in handy.   I called them 'cheats' in an interview recently, and that hasn't gone down so well.   So we'll stick to 'skills and techniques', with 'cheating the wind' being just that.

Thanks to my friend (as in FB), Thierry, for the video.

If it ain't broke, don't fix it!

The Giles G-200 was going well last year. No squawks, all sorted, going really well. I flew the NSW Champs at Temora and immediately afterward went to Tamworth and got my Unlimited LLP with the CASA-man. Full steam ahead for a solid summer of training with a view of maybe moving up to Unlimited in 2011.

But, the A$ was so strong - what could I buy? I HAD to take advantage of it. So I ordered a Sky-Dynamics sump, cold air intake and 4-1 exhaust. I didn't NEED any of this, the 'plane had more performance than I could currently use, my only concern on occasion was oil pressure drops. Regardless, off went the money and in due course it all arrived. Merry Xmas to me..
In between harvest and New Year I fitted it all up, changing some cable runs and oil cooler hoses etc, all with the goal of less weight and less complexity. I was really happy with the finished job - neat, sanitary, light and simple! There was only one problem - it ran like crap. Rough, some cylinders lean, some rich. At WOT it felt like two cylinders dropped out altogether. Horrible it was, really bad. And it was hotter. Oil temps had always been marginal, now they were over redline after a sequence on a warm day.

I tried to sort the problems, but nothing really helped. I suspect oil temps were up due to the loss of cooling from the fuel/air mixture going through the sump, and maybe a hot cylinder or two.
The cold-air intake with no plenum, no heat from the oil and sharp bends to the intake tubes just would not play nicely with the Ellison TBI I'd used with success up to then.
So what do I do now? Put it back to original? I'd trashed my old inverted oil lines to make the new ones. I'd spent the money....and the exchange rate is so good, right? So.........
I investigated fuel injection options and ordered an Airflow-Performance FM-150. Delivery will be six weeks....what! So much for Summer training.

Eventually it arrived, after only three weeks, and I started installation. Not as straghtforward as you would like. Due to the previous mixture conniptions, I'd bought and installed a 4-channell EGT gauge. I also had to change the low-pressure electric boost pump (Facet - simple cheap type) for a high-pressure one (Weldon - heavy, dear). Luckily I had the old one that was in the airframe when I bought it. The engine driven fuel pump also needed changing for a high-pressure type. More $$ and a bastard to change with the engine on.
And, surprisingly (or maybe not, it is an aircraft after all...) the servo orientation was limited by the Sky-Dynamics intake support struts, making the throttle and mixture cable runs more difficult, and putting the fuel supply and outlet ports in less-than-optimum positions. I thought being in neighbouring US States and this being a 'typical' acro combination, it would fit up sensibly.
Solution - simple, drive to Sydney (400km one way) and purchase special hose fittings to do what I needed.

Finally it is all on, and ground runs are complete. Seems to run OK. Not as tidy an install as the Ellison, and substantially heavier. I haven't weighed it yet, but it won't be sub-900lb as it was before. And the CG will be further forward.
So for my $X,0000 I got a heavier, less balanced aircraft! Maybe, hopefully, I gained a few HP and guaranteed oil pressure in all attitudes.

Somehow, I think my $$ would have been better spent on avgas. So, next time - if it ain't broke, don't fix it!

Postscript: So far two test flights and some gentle aeros. The A-P FI is doing as it should, only the idle needs adjusting up a little. EGT's mid 1200's at WOT leaning to mid-1400's before power goes down (my probes are 6-7" from exhaust flange). 25-30F max. EGT spread most of the time. The trim has changed, as expected. Time to boogie!