Forum: General

STBYGAIN or GUMS, I did not find what the allowed AOA and roll values are when you are in CAT I or CAT III. I found some figures but it was not clear about the CAT switch. Do you know about it?

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'cat

I seem to remember about 18 degrees max AOA in Cat 3, and about 13 degrees for the point where the Gee command was reduced to reach one gee at 18 degrees. I'll have to post a diagram of the gee schedule versus AOA. Maybe Habu can help me, as I don't have a lotta cool graphics crapola available. I'll try sending him something and he can dress it up for us to look at. I have the original F-16A FLCS data that has ALL THE CURVES/FUNCTIONS for all three axis, leading edge flaps, and more!

STANDBY can pull out his Dash-One and provide the exact answer on the AOA/gee when he reads this.

Remember, I flew this thing back in early-mid 80's. Much has changed.

out,

Last edited by habu2 on Jan 12, 2004 - 02:52 PM; edited 1 time in total

Dug out my Block 50 -1 and the AoA G limiter function graph shows - for CAT I - 9 Gs at 15 degrees AoA, linearly decreasing to 7.3 Gs at 20.4 deg AoA, and from there linearly decreasing to 1 G at 25.2 deg AoA. CAT III clips the left side of the 'curve' at different spots depending on gross weight, for 30K GW the curve starts at 1 G at 15.6 deg AoA and increases linearly to where it intersects the CAT I line at about 8.3G and 17 deg AoA.

FLCS limiter functions are shown as:

CAT I

Pitch - max AoA 25 deg, G commanded below 15 deg AoA, G/AoA limited above 15 deg AoA

Roll - max roll rate command decreases with: (1) AoA over 15 deg, (2)airspeed below 250 kts, (3) horizontal tail deflection more than 5 deg trailing edge down, (4) total rudder command exceeding 20 deg and (5) combination of horizontal tail greater than 15 deg trailing edge down and AoA above 22 deg

Yaw - max pedal deflection command reduced for (1) AoA over 14 deg w/ zero roll rate, (2) roll rates above 20 deg/sec, and (3) zero rudder authority at 26 deg AoA

CAT III

Pitch - max AoA 16-18 deg depending on GW, G commanded below 7 deg AoA at 100 kts to 15 deg AoA at 420 and above, G/AoA above 15 deg AoA and 420 kts

Roll - mac roll rates command reduced by approx 40% of CAT I, additional decreases as function of AoA, airspeed,, horizontal tail position and total rudder command

Yaw - max pedal deflection command reduced for (1) AoA over 3 deg w/ zero roll rate, (2) roll rates above 20 deg/sec, and (3) zero rudder authority at 15 deg AoA

Things are a bit different during takeoff and landing, for instance roll rates are cut in half.

Above 35 deg AoA (not a typo) the yaw rate limiter cuts out stick roll commands and automatically provides both roll and yaw axis anti-spin control inputs to the FLCS. Below 5 deg AoA and 170 kts the yaw rate limiter provides anti-spin rudder inputs, pilot roll and rudder commands are cut out only when MPO is engaged. Max rudder deflection (30 deg) is alwats available through ARI and stability augmentation.

And that, as they say, is only the tip of the iceberg... Shocked

(edited for spelling, 12 Jan - GregD)

Wow, thanks a lot for info! Very Happy

I don't think this has been posted on this thread yet but the January issue of Combat Aircraft magazine states the F-16C that crashed was SerNo 87-0327, a <a href="f-16_forum_viewtopic-t-446.html">Block 32J machine</a>.

For further discussion, see: <a href="http://www.f-16.net/f-16_forum_viewtopic-t-483.html">T-Bird Crash Accident Report Released</a>

A couple of years ago we used our UH-60 to fly the team around the perimeter of March to pick points, etc. We called for clearance as "Thunderbird 7 1/2" and then asked the team to stand-by for the "Blackhawk Pull". Quick hovercheck, 20ft agl down the runway, hit 140 knots, 3...2.....1, armpit full of collective, level at 1000 feet, show's over. The team had a jolly good time with that one. Lead made some comment about solo's not being able to turn right without rolling left first, so we settled into a hover on landing (something no Viper can do) and did a 270 pedal turn to the left to exit stage right.

Great bunch of guys.

"Every jet jock loves helicopters when he is riding a hoist"

Here's an animated .gif of the ejection sequence. It has been sent to us by Jason W.

Cool - you can see the canopy shadow cross the right wing. And notice the rising horizon line, even in the split second that elapsed during this sequence.

right click>save as Very Happy

The T-Birds PAO tells me that vid is now released, as well as the down throat photo. So I finally put together a page on this ejection on my site. You can access it from the main page. I put in a bit of a description of the ejection events you can see, and linked it to photos of the parts I am discussing.

I'll probably add more later, maybe copy some of the posts I made in this or other threads, but I have to review them and see if they make sense to incorporate. I am also seeking other people's photos, like the ones on that TV station's site. I need to get permission to use them so if anyone reading this has photos, contact me. I also clipped the video to a 5 second WMV, which means it takes up 140kb instead of 4mb...

Kevin
The Ejection Site
http://www.ejectionsite.com

The F-16 like many aircraft today has a fly by wire control system. What that means is that the pilot's input is something of a vote. In this case, Please get your nose and then flight path away from the ground. The computer then positions the controls to do as requested. Note the leading edge devices in the down position. This is due to the slow speed/high angle of attack and the request for more; not the pilot putting them down. F-16's are fun to watch taxi the computer is constantly trying to compensate for bumps in the taxiway resulting in the elevators "bouncing" up and down. Another offshoot of this is that the F-16 will virtually NOT stall. The computer will not let it even if the pilot wants it. The real advantage in the F-16's case is that dynamic stability can be drastically reduced resulting in better turn capability as the tail doesn't need to be downloaded for stability.....I think what happened here is that the pilot misjudged the altitude required for the maneuver. Sometimes small errors are very expensive.

Um...

...yeah.

While the FCS will do its best to prevent you from stalling the jet it is still possible to rate thru the FCS limiters and enter a stall. You really have to be trying to do it though.

Mal, check out the <a href="f-16_forum_viewtopic-t-586.html">Deep Stall thread</a>.

I have moved the discussion on the FLCS control to a new thread: http://www.f-16.net/f-16_forum_viewtopic-t-857.html

Forum: General

Thunderbird crash 14 Sep 2003