Aerobatic Harness

[Ruckus]

I have just imported a Grob G115 into Canada for some basic aerobatics. This aircraft doesn't have an inverted system so I won't be hanging from the belts for any period doing anything inverted. The present harness has a Schroth rotary buckle that doesn't always want to release. (took me a couple of minutes to loosen the belts off and worm myself out after the last flight).
I've also heard that rotary buckles can release at the most inopportune time too. I would like to hear your opinions or advice on options. Are there better rotary buckles out there? Could a hooker harness be retrofitted in a certified a/c without too much hassle. Would the hooker be overkill?

Thanks

[Hedley]

We use Hooker harnesses. Installed one in the Citabria
a while back, the harness came with all the paper required.

I personally like the Hooker - you can really
tighten it down, for the negative G's.

Main problem with a Hooker harness is the heavy,
bulky ratchet, which is basically a come-along. Some
people prefer to NOT use them in the front seat
of the Pitts, because people drop them, and take
chunks out of the fiberglas armrests.

The stock aviat harness is basically a 5-point
seatbelt (black), with a second (red) lap belt
for backup. That works ok, too. Doesn't do
as much damage when they get dropped.

I don't much like the rotary thingie. There's
a dead Snowbird pilot because of it, IIRC.

[cgzro]

Many years ago a well known airshow pilot called Bob Hoover was flying a P51 mustang in an airshow. His seatbelt came undone, well actually the seat came off the floor and the belt was attached to the seat. This caused him no end of grief but being he was Bob Hoover/aerobatic God he survived. After that he installed two seat belts in any aircraft he was doing aerobatics in. Each attached to different airframe components to provide some redundency.

This has been pretty much common wisdom in the aerobatic world for quite some time now and is required for any competition aircraft, all modern aerobatic planes destined for contests have two redundent systems now, so its probably wise to have a second lap belt installed too. As far as the rotary is concerned, if you had trouble getting out of it sitting in a hanger you can bet you won't be getting out of it in the air/broken airplane so I'd ditch it immediately. As Andy points out there was a Snowbird accident not long ago attributed to a seat belt failure. Note sure why they only had the one belt in the Tudor, or is that common for all military aircraft?

[Ruckus]

Just got a reply from the AME. One set of replacement belts, the same as I have will cost about $600. and three weeks. I might still look into the hooker harness. Years ago I remember flying in a Pitts S2 with the extra lap belt. More recently I flew in a Decathlon with the hooker ratchet system, but I don't remember a second lap belt. The grob, is a composite a/c, and although I haven't seen it taken apart I believe the seat pan is bonded in. I'll have to take a closer look to see where the belts are anchored. I do like the simple mechanism of the hooker better than the rotary buckle, and I have to question why the rotary mechanism has failed after only 450hrs.
Thanks for the replies.

[fougapilot]

Note sure why they only had the one belt in the Tudor, or is that common for all military aircraft?

Having an ejection seat makes it somewhat difficult to have a set of seatbelts attached to the airframe... not impossible, simply complexed and difficult. Nearly impossible with a "field" modification, would have to be designed into the seat jettison system.

Generally speaking, military pilots do not fly negative to much. It has nothing to do with the fact they dislike it or they are "wimps" compare to unlimited aerobatics pilots. It has all to do with the fact that when doing negative manoeuvers you don't see where you are going. Military "aerobatics" are all about killing things either on the ground or in the air. The earlier you see the target, the better chance you have of killing it. This is why you will always see fighters pilots "roll&pull' instead of pushing -5Gs. With the roll&pull, they see the target as soon as they have rolled and can line up with it, with the push they would have to guess where it is until is appears from under the nose.

Given the rate at which people eject from these airpane versus the rate of seatbelt failures in their limited negative Gs environement (limited compare to unlimited aerobatic pilots), I think they are still better off with the rocket.

F

[Hedley]

(digression about negative G's)

You might be right Dan, but the western military world
has had a bias against negative G for decades, that
simply wasn't shared by the eastern bloc.

And it was systemic - since the pilots didn't do it, the
aircraft weren't designed with it, so the next group of
pilots couldn't do it, either, and concluded it was dumb.

But in WWII the Germans used negative G quite aggressively
and successfully against the British.

In a recent conversation with Fern Villeneuve (Sabre
pilot with the Golden Hawks and quite the stick and
rudder guy - he talked about doing iron bomb tosses by
pushing over the top, rather than the classic pull,
1/2 roll, pull over the top, 1/2 roll, so that he could
keep the target in sight without all the 1/2 rolls, which
he found more disorienting than the push.

[Ruckus]

I'm not too concerned about pulling a lot of negative g's in the Grob. If I just I hold slight negative g's for too long, the engine starts to sputter, and I find that a little bit distracting. It also means a bit of a clean up after the flight to wipe off the oil. I'm just trying to work on doing everything smoothly and getting it as close as I can without pulling negative g's. I'm pretty religious about checking the harness security before each maneuver too, I'm just working it into the hasel check that I learned during my private training.

[fougapilot]

Ruckus,

Sorry if we digressed, it seems to be common around here

I have a 7 points Hooker harness in the Chang (CJ6a) and honestly I wouldn't fly (the way I do) without it. My Chang, like your Grob, has limited inverted capabilities. I can fly inverted for 7 seconds before the oil pressure begins to drop. The fuel would probably last around 10 seconds, but I fail to see the need to test this theory. Some would argue that 7seconds is nothing, but it is sufficient for me to include an inverted pass in my airshow routine. After all, 7 seconds inverted at 140kias will cover nearly 2000ft over the ground which is enough for 70% of the airshows I fly.

But negative Gs aside, when you fly acro you need a good harness. My view on the utility of the seat belt differs a bit from most pilots; you see your regular airplane driver thinks the seat belt is used to keep him on his seat, I on the other hand believe the harness is there to keep the airplane attached to my rear end! I am after all the brain of this organization (ok, i know we could argue this a long time) and since my airplane is somewhat heavy, I need a good harness to keep it attached to me.

I have flown acro in my Chang with both the Chinese harness and the Hooker harness. The difference is noticeable. Having the Hooker harness ties you to the seat much better so that there is little to no movement between you and the airplane. It makes it much easier to feel the real airplane (as opposed to the movement between you and the seat).

I would say if you have the room, go all out on the harness.

Hope this helps,

F