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#51
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"Peter Duniho" wrote in message ... "Chris W" wrote in message news:gj%ae.640$zv1.481@lakeread07... Is there an altitude above the ridge line at which the "mountain wave" effect isn't significant? Probably would be pretty negligible at 23,000 miles. For example. Seriously though, yes...you can sometimes fly high enough to avoid the wave. But that depends on the height of the terrain, the strength of the wind, and of course the type of aircraft. There is no reliable way to know ahead of time how high you need to fly to avoid it. That said, there's being high enough to get all the way out of any noticeable effects of the wave, and then there's being high enough to avoid the wave forcing you too close to the terrain. The former may be impossible, depending on the situation. The latter is usually possible. I have rarely experienced altitude excursions of greater than 2000-3000 feet as a result of mountain wave, so that's a pretty reliable margin for crossing ridges. Of course, there is the question of whether mountain wave can actually push you into the ground. I've never actually heard of that happening, and for it to do so, the part of the air mass you're flying in would have to hit the ground as well. That happens in microbursts, or under virga, for example, but you'd have to be pretty darn close to the ground in the first place for a mountain wave to push you into it. From a practical perspective, a couple of things to consider: higher up may provide less turbulence (though, don't try to fly through a rotor cloud). Also, if you want to most efficiently use the mountain wave to your advantage, pitch up and slow down while it's making you go up, and pitch down and speed up while it's making you go down. This will increase the magnitude of your altitude changes, but you'll be spending less time during the "bad" down areas and more time during the "good" up areas. Fighting the mountain wave is just that: fighting. And no one wins a fight with Mother Nature. Of course, in practice you may have upper and lower limits to acceptable altitudes, and those need to be taken into account. But inasmuch as you can allow your altitude to vary with the wave, let it. Pete Mountain wave systems extend to and often into the stratosphere so it is unlikely that you can fly above them unless you have a new airplane that we haven't been told about :-). Mike MU-2 |
#52
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Peter Duniho wrote:
"Stefan" wrote in message ... Depending on the wind situation, you can expect downdrafts of 10 fpm or even more. No light single will outclimb this, even less at altitude. You need to recalibrate your vertical speed reference. 10 fpm (or 20 fpm, as you wrote elsewhere) is 10 feet per minute. That's nothing, and quite a bit less than any actual up or down that one might find due to mountain wave or similar effects. I have no idea what you meant to write, but it's absolutely false that "no light single will outclimb" 10 fpm downdraft. Pete |
#53
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Peter Duniho wrote:
10 feet per minute. .... I have no idea what you meant to write, I've meant 1000 to 2000 fpm. Stefan |
#54
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Morgans wrote:
"Toņo" wrote Not according to Sparky Imeson.... "...the rotor cloud will be downwind from the mountain range and extend anywhere from the earth's surface to up to mountain-top level". --p.63 of "Mountain Flying" by Sparky Imeson Antonio There is some disagreement with this, and here is a clip: Normally the rotor clouds is centered beneath the lenticular cloud. Most often it extends anywhere from ground level to mountaintop level, but is frequently observed up to 35,000 feet. Destructive turbulence from the rotor rarely exists more than 2,000-3,000 feet above mountaintop level. Well? Your last sentence says it..."Destructive turbulence from the rotor rarely exists more than 2,000-3,000 feet above mountaintop level." I see no "disagreement" about it. My point is, just because you clear the ridge, there are still dangers that can ruin your day,snip I agree and never stated otherwise. However, the OP was wondering whether he should take a "mountain flying" course in order to make a cross-country trip at altitudes of 16-19,000 ft. My contention was that this was not *mountain flying* per se and that he was wasting his time thinking that a mountain flying course would in any way prepare him for the trip. The topic is not "are there dangers at high altitudes" as some here seem to be trying to make it; it is: "would one benefit by a mountain flying course if one were flying at high altitudes?" At least, that's how I read it. Thanks for the great link! Antonio |
#55
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Dylan Smith wrote:
In article , Tango Whiskey wrote: read a good mountain flying book like Sparky Imerson's you'll be good to go Sparky Imeson has a mountain flying website with lots of good stuff: http://www.mountainflying.com/ Yes! and here is the link to his free download on cross-country planning.... http://www.mountainflying.com/xcguide.htm |
#56
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"Morgans" wrote in message news There is some disagreement with this, and here is a clip: Normally the rotor clouds is centered beneath the lenticular cloud. Most often it extends anywhere from ground level to mountaintop level, but is frequently observed up to 35,000 feet. Destructive turbulence from the rotor rarely exists more than 2,000-3,000 feet above mountaintop level. http://www.mountainflying.com/mountain_wave2.htm My point is, just because you clear the ridge, there are still dangers that can ruin your day, if the winds are right. Further down in the article, this author talks about rotors that do not have a visible cloud. If the wind is blowing strong, close to perpendicular to the ridge, best wait until early the next day, and see if the winds are calmed down. Hey, I just read, and remember. I have no idea if what everyone says is true. I would rather be safe, than sorry. YMMV -- Jim in NC Hmmmm, I've been through the rotor a few times -- while yanking and banking on the end of a 200' length of towrope behind a tow-plane. The first time is the worst. After that you remember to breathe and you don't suck quite as hard on the seat cushion. When you're headed for the primary wave developed on the east slope of the Sierra, the rotor is unavoidable. Some folks, with more skill than I possess, ride thermals up into the secondary wave and, when high enough slide over to the primary. I guess I never thought of the rotor as destructive. Maybe I shouldn't do that again. |
#57
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Stefan wrote: Peter Duniho wrote: 10 feet per minute. ... I have no idea what you meant to write, I've meant 1000 to 2000 fpm. Still isn't fatal. |
#58
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Newps wrote:
I've meant 1000 to 2000 fpm. Still isn't fatal. Nobody talked about fatal. You just can't outclimb this at altitude with a light, non turbo charged single. So it may indeed become fatal, and has so on a regular basis, for those who don't know how to behave in the mountains. Stefan |
#59
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"Mike Rapoport" wrote in message .net... Rotors do not extend much above the ridgetops. The waves themselves are smooth until reaching the tropopause except the extreme case of breaking waves. Before Mike, Jim in NC wrote: The waves extend way up past the peaks, and so do rotors. I guess it depends on your definition of "way past". As per my other quoted post, about destructive part of the rotor going to 2 thousand over the ridge, I think that is way over. Plus, I want to be well above where the rotor is still destructive, like another couple thousand. That is really way past to me. YMMV I just want people to know that if they are thinking of going over a pass with only a couple thousand to spare, if the wind is blowing just right, they could be in big trouble, whether they see it or not. Right? -- Jim in NC |
#60
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Toņo wrote:
Blanche wrote: And what happens if the engine conks out? Where do you land? How do you land? Maybe he should also take glider lessons, mountain survival, parachuting, and aerobatics prior to the flight. I mean, those disciplines have just as much relevance if not more should a forced landing be immanent. My response addressed your comment about "flying in the mountains". And yes, if you're going to fly "in the mountains" in a single (unless, of course, that single engine is attached to an F16) you really should have some knowledge of mountain survival. How does a knowledge of mountain flying help you to land with and engine out? And how would that differ from any other no-engine landing? OK, you're at 16K over the I-70 in Colorado west of Denver. Let's say somewhere between Georgetown and Silverton. What are you going to do? (And following I-70 between Denver and Glenwood Springs is the absolute worst action you can take). If you've only read Sparky's book it's not going to help much. About the only thing I could think of would be to try to estimate winds and direction based on terrain features. Read Sparky's book and you have some theory to work off of but, really....do you think that this would sufficiently arm you for an encounter with the winds in the mountains? If you do then you have never flown *in* the mountains! Please remember, I'm the one who said reading Sparky's book and nothing else is not a good idea. Flying in the mountains...hm... Half the time I'm in the air, I'm very close to mountains. Personally, I prefer NOT to be "in the mountains". Above, between, sure. As far as *where* you land...you land wherever you can; as in non-mountainous terrain. Again I respond -- if all you've ever done is read the book you're not prepared. And when that happens, all of a sudden you need to worry about mountain waves, density altitude, valley winds, etc. Calculate glide distance from 16K and tell me where & how you're going to land. Well...if you know how far you can glide at 1000 ft you can multiply by sixteen. But that calculation would only give you the no-wind theoretical distance. It also something every pilot should know regardless of whether they are in the mountains or not. And, come on! Are you really going to pull out the ole' whiz wheel and think about "...density altitude, valley winds, etc." when you are dead-sticking it to a suitable landing site? Generally, you *might* have one place to land that is suitable and you can bet your gold-plated E6B you'll take it regardless of the "density altitude". I don't own a "whiz wheel". Well, I do. I just don't know where it is these days. But you point out that "you *might* have one place to land that is suitable"...better yet, you may not have *any* place to land but you still need to get down. But as the OP stated, his flight plan was over mostly flat land. In fact, pretty much follows I-40 to I-25 (watch out for the MOA south of Pueblo -- I-25 goes right thru it) which is very practical. |
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