I've seen that view about a hundred times. The border is not too far past that Hwy 90 bridge. I was at the lake today just slightly east of the bottom right corner of that picture. Didn't see any planes fly over.
It would have been about 11:30 this morning, little wing dip flying over the base just to get a good pic. Had a bit of excitement coming back into San Antonio on the Centerpoint One arrival just past Kerrville. White glider at 5k feet was flying around white puffy clouds pops out from behind a cloud directly in front of us. Evasive maneuver ensues and miss him by maybe 1000 feet. Pretty amazing that somebody would be cruising around in a glider right over one of the points on a STAR. Image Unavailable, Please Login
Right now that guy is on GliderChat talking about his encounter with those damn fuel burning planes. GT
Today for the Herk birthday weekend tour of Texas we flew from San Antonio to Houston then down the Gulf coast then up the Tex/Mex border to Laredo then back to San Antonio. Didn't make it up to the panhandle but overall got to cover quite a bit of the state.
Thought this was funny and obviously made me think of MarkPDX, totally his sense of humor. Image Unavailable, Please Login
Your course brought back many memories of my days at Hondo flying some of the same routes around Laredo and San Antonio in the AT-7's. We certainly didn't cover the ground that you did, though. All of that seems as though I dreamt it.
A nice retrospective on the Herk put up by Lockheed Martin: [ame=http://www.youtube.com/watch?v=jpnhQwF5Ndk]60 Years and Climbing - YouTube[/ame]
Curious what it's like to be airdropped? [ame=http://www.youtube.com/watch?v=qRxmc0sgImg&sns=em]CDS drop - YouTube[/ame]
Bit of a silly question, but why aren't her props at the feathered position when her engines are not running, like most other turboprops?
Most other turboprops that you see are what are called "free turbine" engines. That is, there is a turbine section (usually a couple of stages) that directly turns the prop and there isn't anything else on that shaft. Consequently that shaft will turn easily (you can turn the prop with your hand). If it wasn't feathered it would spin in the wind like a windmill. Since the lube system is on the engine gas generator shaft the engine could spin and there would be no lubrication to the gears and bearings, which if did it for a long time could do damage to those parts. For that reason props on free turbine engines are often "feathered and tethered" to keep them from windmilling when the airplane is tied down outside. Since the gas generator is separate when you start the gas generator as it comes up to speed the oil pressure comes up and "nu-feathers" the prop and away you go. In addition, if you lose oil pressure the prop will feather itself. If you are at lower speeds and the gas generator spools down and doesn't windmill fast enough to keep the oil pressure up (or if you had a catastrophic engine failure) the prop would self feather. On the Herk, the engine is what is generally called a "single spool engine". That is the prop is geared to one shaft that has all of the rotating parts on it, all of the compressors and turbines and accessories. That also means that when you start the engine you have spin the prop with the starter and that takes a lot of power as it is. If the prop was feathered it would take a lot more power to spin up to a high enough speed to light off the turbine. Also with all of the drag of accessories and pumps as well as the main gearbox, it would take a lot of wind to windmill the props on a Herc. Some turbine engines have a prop brake to lock up the props so that tethering them is not required, but the ubiquitous PT-6's don't so you see tethers on them to keep them from windmilling.
Oh! Yes, I had neglected to consider that it may not be a free turbine. Thank you for your very detailed reply.
The video I attached to post #34 above has moved but is still available: [ame=http://www.youtube.com/watch?v=Xri-a9qAR0Y]C-130 Hercules - 60 Years and Climbing #LockheedMartin - YouTube[/ame]
A plane I used to fly heading out the door, doubtful it will ever be back here. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
+1 Indeed. Pretty much the same thing we see on F1 cars..... The aero nerds *hate* it because it means it's not "optimum".... But behind a prop, no big deal I guess...... Cheers, Ian Image Unavailable, Please Login
As noted they are tip vortices and are visible in any humid conditions. That pic is about "medium" as far as they go. The J model C-130 with its six bladed props also has tip vortices however they are not as prominent. Something I have watched for a lot but never have seen is if there is any vapor trails when the props change pitch and go into reverse during landing. I would think that there would be a momentary vapor cloud when the pitch changes and the air is disrupted. Any thoughts on that Bob? I'm gonna see if anybody can identify the tail flash / destination.....
ok.. interesting.. so mostly noticed in hot/humid situations? I hadn't seen that off props in person before.. but then I'm not in that kind of area.. nor taken a look at a million pics or had huge background in it either.. edit: I see my post answered millisecond before hit "post"!
Yeah, it's really prominent in places like Bahrain where it's 110 degrees and 95% humidity. Here is a pretty good pic of a J with prop trails I took a while back. Image Unavailable, Please Login
One more If you are looking to take pictures of prop trails a shutter speed of 1/1000 or less typically works well in my experience. . Image Unavailable, Please Login
I don't know what they are implying by "optimum". Any time you work the air that hard it's going to let you know it. Those wings are at an extreme angle of incidence, highly curved, and producing a lot of lift and energy. Unless there are some serious fences at the ends, the high energy air is going to spill around into the low pressure areas and cause visible changes in the velocity. Nobody gets high lift without high drag. I think there is a more efficient way of achieving down force.
Indeed. Exactly!.... And for these guys that's a very bad thing! We used to see those "vapor trails" any time they were running in high humidity or damp air. Today, it's very unusual under any circumstances. Couldn't agree more!... You can never get something for nothing! Really? Care to share? You could come out of retirement and earn a gazillion $ if you could do it! [Seriously! ] I don't know if you follow F1 at all, but here's a couple of pix of (fairly) current wings. For sure, as the old saying goes, "the air's going to do what it wants to", but these guys are trying pretty hard to mess with it!...... Cheers, Ian Image Unavailable, Please Login Image Unavailable, Please Login
