Pilatus B4 PC-11 wing repairs

On Wednesday, January 7, 2015 2:14:33 PM UTC-6, Cookie wrote:

Funny thing about that Pilatus...On aero tow, during ground roll and take off, you HAD to hold full forward stick....if you didn't hold it to the stop, the glider would take off and continue to climb, and then full forward stick would be useless...it would just keep climbing....You had to hold the stick forward, and do the ground roll in a nose down attitude...and it took off in that nose down attitude too....I guess the wings are rigged with a high angle?

Other wise really nice glider.

That sounds like there was a real problem with the CG or stab/elevator rigging (or the wing incidence?) on that particular B4. Long ago, I flew a couple of B4s (no, actually, it was the same one in two different places, Vacaville and Estrella, separated by several years!) and other than pitch being a bit sensitive (kind of like a 1-26), it otherwise was an easy plane to fly. Definitely did NOT have to hold the stick forward for takeoff or tow!

Kirk
66

Yeah, it seemed like a balance problem...but we ran the numbers...

Did they have CG hook? How heavy are you? Funny thing with a pilatus...the trim ballast weights go on the TAIL !! Heavy pilots need tail ballast!



So it can take a fairly light pilot without trim ballast, and as the pilot gets heavier, you add weights to the tail...If I remember, there were two "plates"...small one, big one...you could use either, or both to give proper balance...they were bolted on externally...

Cookie




That sounds like there was a real problem with the CG or stab/elevator rigging (or the wing incidence?) on that particular B4. Long ago, I flew a couple of B4s (no, actually, it was the same one in two different places, Vacaville and Estrella, separated by several years!) and other than pitch being a bit sensitive (kind of like a 1-26), it otherwise was an easy plane to fly. Definitely did NOT have to hold the stick forward for takeoff or tow!

Kirk
66

On 1/7/2015 3:48 PM, kirk.stant wrote:

That sounds like there was a real problem with the CG or stab/elevator rigging (or the wing incidence?) on that particular B4. Long ago, I flew a couple of B4s (no, actually, it was the same one in two different places, Vacaville and Estrella, separated by several years!) and other than pitch being a bit sensitive (kind of like a 1-26), it otherwise was an easy plane to fly. Definitely did NOT have to hold the stick forward for takeoff or tow!

I agree. I have about 70 flights in 2 different B4s and both would aero
tow normally with the stick more or less centered.

Tony "6N"

This one, once you "got going" towed just right with the stick near center....but on initial take off, if you didn't have the stick forward, it would "kite"...In gliding flight it was fine...trim worked as you'd expect and stick was where you'd figured it should be. Thermalled great and benign stall..

But maybe this glider was "cursed" because some other weird stuff happened....

We had one club member, and every time he flew it, it released prematurely from tow....never happened to anyone else, just him...and every time...The guy was big and tall...and had big feet and wore big shoes...we figured he must have gotten his feet against the release cable...but we could not simulate the deal on the ground...

Then the glider had a series of flights where it did not release from tow! This happened to several pilots...it did release after several pulls on the release cable and some cursing etc...One time I think they intentionally broke the rope...

When we had those release failures, we checked the release on the ground...under tension, without tension, with extreme tension and all ways we could think of...never failed on the ground...

Finally, I took the whole interior apart...hidden in the tow hook mechanism was a "trim screw" which must have fallen out of somewhere, and was bouncing around in the tow mech...most of the time it stayed out of the way, but it could jam...

They big foot guy moved away, and we never had another release problem...the glider served the club well for many years and many hours...until it finally got put out of its misery!

Cookie







On Wednesday, January 7, 2015 7:03:46 PM UTC-5, Tony V wrote:
On 1/7/2015 3:48 PM, kirk.stant wrote:

That sounds like there was a real problem with the CG or stab/elevator rigging (or the wing incidence?) on that particular B4. Long ago, I flew a couple of B4s (no, actually, it was the same one in two different places, Vacaville and Estrella, separated by several years!) and other than pitch being a bit sensitive (kind of like a 1-26), it otherwise was an easy plane to fly. Definitely did NOT have to hold the stick forward for takeoff or tow!

I agree. I have about 70 flights in 2 different B4s and both would aero
tow normally with the stick more or less centered.

Tony "6N"

On Wednesday, January 7, 2015 3:23:25 PM UTC-6, Cookie wrote:
Yeah, it seemed like a balance problem...but we ran the numbers...

Did they have CG hook? How heavy are you? Funny thing with a pilatus...the trim ballast weights go on the TAIL !! Heavy pilots need tail ballast!



So it can take a fairly light pilot without trim ballast, and as the pilot gets heavier, you add weights to the tail...If I remember, there were two "plates"...small one, big one...you could use either, or both to give proper balance...they were bolted on externally...

Nothing unusual about aft ballast weight for a heavy pilot - got some of that in my LS6 these days! But back then, I was well under the 220 lb that the B4 flight manual says is the pilot weight that calls for the aft ballast..

And they are all CG hooks.

Was that B4 ever damaged and repaired?

Kirk
66

To me, what's unusual about tail trim ballast is that as the pilot weight goes up, the ballast weight goes up too...making it easier to hit gross...

The "schweizer" way, Light pilot adds ballast, heavy no ballast...

But 220 is pretty high for not needing ballast....

But none of the "regulars" who flew this glider were anywhere near 220...more like 135 to 165....I probably weighed in at 150 back then...

Specs show "empty weight at 508#...so it looks like pilot could go all the way up to 262#.....so us 150-pounders were probably far aft on the CG...no?

If memory serves me correct, we started putting a 25 lb lead sheet under the seat...to avoid the kiting problem...

I don't know what happened to the wreck....Anybody in ACA have any info on this?


cookie

On Wednesday, January 7, 2015 7:33:22 PM UTC-5, kirk.stant wrote:
On Wednesday, January 7, 2015 3:23:25 PM UTC-6, Cookie wrote:
Yeah, it seemed like a balance problem...but we ran the numbers...

Did they have CG hook? How heavy are you? Funny thing with a pilatus....the trim ballast weights go on the TAIL !! Heavy pilots need tail ballast!



So it can take a fairly light pilot without trim ballast, and as the pilot gets heavier, you add weights to the tail...If I remember, there were two "plates"...small one, big one...you could use either, or both to give proper balance...they were bolted on externally...

Nothing unusual about aft ballast weight for a heavy pilot - got some of that in my LS6 these days! But back then, I was well under the 220 lb that the B4 flight manual says is the pilot weight that calls for the aft ballast.

And they are all CG hooks.

Was that B4 ever damaged and repaired?

Kirk
66

On Wednesday, January 7, 2015 at 12:03:09 PM UTC-6, Charlie M. (UH & 002 owner/pilot) wrote:
On Wednesday, January 7, 2015 9:20:56 AM UTC-5, Luke Szczepaniak wrote:
On 01/06/2015 10:05 PM, WB wrote:
We live in constant fear of what is going to get busted next.


I think this is may be an issue at most if not all clubs, I am always
amazed how carelessly some members treat equipment....

Luke

We "retrain" some club members by having them work on the repairs along with the rest of us...... ;-)

As it should be