This was a check-ride?
I thought the FAA check airman were there mostly for checking new captains?
Interesting how almost everybody learns a little bit differently. I just know what hand I write with and that's the reference point.
Why a Rear Engine For the P-39?
- Thread starter MIflyer
- Start date
It's an additive effect; more power plus leftward pull working through a longer moment arm makes for a startling first takeoff when the owner gets his plane back with its shiny new proboscis. Not only the longer moment, but also more keel area forward usually creates the need for a skeg or dorsal fin aft to compensate.
Cheers,
Wes
This was what was called a route check. If they need to go somewhere and don't feel like spending hours in the car, they just "drop in" on an airline flight going in the right direction for a no-notice observation of a crew or two in everyday operations. Needless to say, this isn't popular with airline people as it often results in bumping an additional passenger and/or displacing any scheduled jumpseat riders.This was a check-ride?
I thought the FAA check airman were there mostly for checking new captains?
A formal checkride is usually administered in a simulator by a senior company instructor who's been FAA certified as a Check Airman. Captains get this every six months and FOs at least every year, although sometimes it's divided into two segments six months apart.
New Captains (and nowadays FOs) have to complete a period called Initial Operating Experience, or IOE, with a company Check Airman, or very occasionally, an FAA Inspector, serving as the other pilot. After they've completed IOE, most go into reserve status, where they fill in for other pilots who are sick or on leave or vacation. After they've gained enough seniority they finally get to bid on line schedules. The only exceptions to the reserve status gig are pilots returning from furlough and have enough seniority to hold a line. The exceptions to this reserve gig are pilots returning from furlough who have enough seniority to hold a line.
Cheers,
Wes
Last edited:
So, it's kind of the aerial pop-quiz?
And he ended up with the plane flipped onto it's back?
Hello XBe02Drvr,
If one goes back to basic principles of what P-factor actually is, I don't see how any other conclusion makes sense.
As I understand it, P-factor is the result of the propeller axis being inclined upwards in relation to the direction of motion.
On a tail dragger with a tractor propeller rotating clockwise as seen from the cockpit, the descending blade on the starboard side encounters a higher angle of attack than the ascending blade on the port side.
Because of the difference in angle of attack between the prop blades on each side, the starboard blades generate more thrust than the port side blades and there is asymmetric thrust Forward which causes a pull to port.
So as I see it, it is caused by a difference in forward thrust between right and left sides rather than a direct force to the side or is there something more to the story?
- Ivan.
That's right, and the further forward of the CG that pull to port is applied, the more leverage it has to displace the aircraft from it's heading, IE to pivot the aircraft about its vertical axis.
Cheers,
Wes
I suppose you could call it a pop quiz, although there's no "quizzing" involved; the Inspector just sits there, listens to the communications and observes the crew's routine procedures, takes notes and writes a report for his/her supervisor. In the rare case of exceptional crew performance, either good or bad, he/she will offer a critique to the crew or write up a violation of FARs, if warranted. In my experience, this was rare, and usually the Inspector went off and left the crew wondering.
The case of the 1900 that sat down on its tail was a different scene altogether. That Inspector was bruised on his butt and his ego, as well as water and glycol stained on his expensive suit, and he was justifiably pretty irate. He relieved the Captain and me of our licenses and wrote us up for careless and negligent operation and numerous other FAR violations, incuding falsifying flight documents. Since the baggage door got dinged against one of the baggage carts when the plane sat down, he declared it unairworthy and the company had to send another plane and crew to fly the one hop to complete our trip sequence. This turned out to be in vain, as none of the seven passengers going on to PLB would get on one of our planes, and the company wound up sending them on in taxis and limousines.
The thing that saved our bacon was that I still had the manifest sheet we were given in BOS and it agreed with my weight and balance flimsy, and didn't reflect the 400 pounds of extra cargo that was actually there. Piedmont's BOS station wound up taking the rap for the fiasco, and some dispatcher down there lost his license.
Cheers,
Wes
Hello XBe02Drvr,
Is P-factor a vector to PORT or is it an imbalance of two FORWARD vectors each with a lateral offset?
I believe it is an imbalance of two FORWARD vectors in which case the net imbalance is what we are interested in and the lateral component of that vector gets smaller as the distance from CoG to Propeller gets larger because the forward vector becomes more aligned radially to its offset from the CoG.
.........
After writing the above notes, it occurred to me to actually do some hypothetical calculations with a spreadsheet.
I will check the formulas again when I get the chance, but the results are rather amusing.
My claim was that the tangential component decreases with distance of propeller to CoG.
Your statement was that the moment arm gets longer as distance from propeller to CoG increases.
The net effect is that they cancel each other out. (!)
The resulting torque about the CoG remains exactly the same; Thus nose length makes no difference at all from a P-factor perspective.
I will check everything out again when I get the chance, but the results seem pretty logical.
By the way, the Beech 1900D crash wasn't entirely an Aft CoG problem if the Wikipedia link was accurate.
There was an error in the rigging of the elevators so that full control deflection was not possible.
Either the Aft CoG or lack of elevator controls alone would not have been fatal, but together they were.
- Ivan.
I prefer the NTSB report over Wiki. IIRC, not only was the elevator misrigged, but so was elevator trim, so when they set the elevator trim correctly (according to the trim indicator) it was actually trimmed much more nose-high than indicated.
I am neither an engineer nor a mathematician, so my understanding is defined by what I've seen in training manuals and simplified discussions such as "Aerodynamics for Naval Aviators".
The depictions I've seen are consistent with a vector to port located at the plane of the propeller disk.
Cheers,
Wes
Wes,
I always thought it odd that an FAA "person", could give you a Checkride on a plane they are not current and or qualified in. Government oversight at its best...
Cheers,
Biff
Strictly speaking, they can't. Any Inspector can route check a crew as long as they have that company's ops specs for that aircraft available as a reference. That is not a checkride, per se, but an operational observation. There's no interference with the crew's duties allowed and no intervention except in the case of gross misconduct, and is supposed to be invisible to the public.
I've never been given a bonafide checkride with an FAA Inspector who wasn't qualified in the aircraft. In fact, I took my Captain upgrade/aircraft type rating ride with the FAA Inspector who had overseen the 1900's certification for airline service. He was the manager of the local FSDO, and since we were the launch customer for the aircraft, he got to oversee the process and become the first FAA employee type rated in it. All of our company's type rides went through him. Our Director of Ops was certified to do type rides in the bird, but I never saw him do one. He was so busy doing recurrents, he kept falling behind on his desk work, and had office staff doing work that was rightfully his, so he didn't begrudge Chuck the type rides. And the FSDO staff loved it too, because it got the boss out of their hair, and he always came back from flying in a good mood.
Cheers,
Wes
Last edited:
