Hurricane tracking aircraft vs airliners

[Phil Bunch]

It occurred to me that the US regularly flies 4-engine turboprop aircraft directly through hurricanes each year, with winds up to 170 or so miles per hour, and worst case scenario lightning, rain, etc, with no apparent risk of losing the aircraft to turbulence damage or lightning.

Is there any reason to suspect a relatively new Airbus would be less capable of flying through tropical thunderstorms than hurricane hunter aircraft when it flies through a maximum strength hurricane?

I don't really understand how a hurricane hunter can safely fly through a hurricane since its winds are so low as it crosses the eyewall/eye of the storm.  The sudden changes in wind direction and magnitude seem too severe, in my intuitive judgment.  Obviously, my intuitive judgment is wrong.

Perhaps the military aircraft (Lockeed P3 Orion I think) used  for the hurricane tracking are more rugged than a passenger jet.  

Could a 744 fly directly through a hurricane safely?

[Peter Lang]

Hi Phil,

I think a 4-engine turboprop operates with other airspeeds and in other altitudes than a jetliner. It would make a big difference if turbulences and  hailstones will hit your plane with 120 kts, 220 kts or 320 kts IAS.
And the hurricane hunters do not have normal passengers on board who need waste bags when they are going in rollercoaster mode and complain for "sloppy flying"  

During my first flying lessons I was told to reduduce speed immediately if I could not avoid to fly into a rainshower.  This was for a normal Cessna.

Boeing manual says that the turbulent air penetration speed is 290 to 310 kts IAS  or Mach .82 to .85 whichever is lower.

Peter

[John Davis PC]

A couple of films I have seen suggest that the Hurricane hunters have a very rough ride and do indeed run the risk of a break up.

In the case of the AF flight it was probably more likely that the aircraft broke up in Turblence, in these types of violent thunderstorms you have very strong updrafts of air right next to rapid downdraughts, it is possible to fly through the edge between the two and slice the plane in half much like a guilotine. This happened to a ritish Airways 707 near Mount Fuji.  It is very rare but seems a more likely explanation than general turbulence as they are made to withstand these even if its extreme.
it could also answer the presurisation problem if the tail was sliced off.
Other possibility is also a bomb or large decompression caused in a similar way to the Qantas Oxy bottle incident.

I guess unless the Flight Data Recorders are found we will never know.

Cheers  PC

[Will]

I'm pretty sure that even hurricane hunters use their radar (and their Strike Finders) to avoid the worst of the worst. My impression is that they don't fly a straight track directly through the storm, without caring what's up ahead, but that they actually weave and dodge and go where they can. I'd guess you can fly between the most active cells, and avoid high risk.  The high winds themselves wouldn't be as much of a problem, as long as the whole air mass has a similar velocity, but big cells (i.e. intensely shearing up and down drafts) would.

Wikipedia says the WP-3D Orions they used are beefed up, and I don't doubt it. But I'd wager they could still get wrecked if they fly into the wrong part of the hurricane. Like in an embedded tornado for example, or fist-sized hail.

Will

(Edited)

[Phil Bunch]

I'm pretty sure that even hurricane hunters use their radar (and their Strike Finders) to avoid the worst of the worst. My impression is that they don't fly a straight track directly through the storm, without caring what's up ahead, but that they actually weave and dodge and go where they can. I'd guess you can fly between the most active cells, and avoid high risk.  The high winds themselves wouldn't be as much of a problem, as long as the whole air mass has a similar velocity, but big cells (i.e. intensely shearing up and down drafts) would.

Wikipedia says the WP-3D Orions they used are beefed up, and I don't doubt it. But I'd wager they could still get wrecked if they fly into the wrong part of the hurricane. Like in an embedded tornado for example, or fist-sized hail.

Will

(Edited)

Will,

Thanks for the WIkipedia suggestion for learning a bit more about this most unusual form of aviation.

Here's a quote that is most confusing to me - it just doesn' t seem reasonable that one could fly an aircraft, even beefed up, directly through the eyewall of a hurricane - my very limited understanding is that the winds drop from hurricane force to perhaps a few tens of miles per hour as one crosses the eye of the storm.
-------------------------------
"The Lockheed WC-130J aircraft is a venerable workhorse. It flies directly into the hurricane, typically penetrating the hurricane's eye several times per mission at altitudes between 500 and 10,000 feet. The 53rd WRS "Hurricane Hunters" operate ten WC-130J aircraft for weather reconnaissance.

The Lockheed WP-3D Orion aircraft flown by the NOAA Hurricane Hunters are heavily instrumented flying laboratories specifically modified to take atmospheric and radar measurements within tropical cyclones and winter storms."
--------------------------------

I wonder if the wording here is misleading - perhaps they fly at 10,000 feet across the eye of the storm and only fly at 500 feet for special purposes, well away from the unstable parts of a storm.  I think the eye is only about 10 miles across but I haven't researched the topic.

It's surely impossible to fly ANYTHING across the eye of a hurricane, especially at low altitude.  

I have a distant memory of watching a TV documentary on these aircraft and their flights but the only thing about the flight I can now recall is that the aircraft bounced around a lot! (grins)  They dropped special instrument packages out of the aircraft from time to time, and the instrument packages had radio transmission units to send assorted metereological data as they fell through the sky.  

Perhaps this is a good opportunity for me to try out Microsoft's new search engine, at bing.com.  My initial impression was that it has a prettier interface than Google and that it may be a bit more structured.

Thanks for your thoughts on flying into "known catastrophic turbulence" or whatever one wishes to label flying into a hurricane. (more grins)

[Phil Bunch]

Will,

I did a little more internet searching and found the home page of the US Air Force Reserve unit that does the "hurricane hunting".

Their web page makes it clear that they fly at 10,000 feet to drop the "Dropsonde" instrument probes into the hurricane, and they only fly at low altitude (500-1500 feet) for measuring wave heights, etc, no doubt well away from the eye of the storm.

Here's the URL for their web page:

http://www.hurricanehunters.com/mission.html

It's very hard to view this web page due to their use of black text against a dark gray background, but in my web browser (Firefox), I simply used the "Print Preview" mode with graphics disabled and I then see the text as black on a white background.

My guess is that the eye of a hurricane at 10,000 feet altitude is not as well-defined as it would be near the surface, but this is yet another topic I haven't researched.  

Basically, it would be interesting to know how much the wind speed varies as one flies across a hurricane at 10,000 feet.  They bring civilian scientists, etc, on their flights, so there must not be a grossly excessive hazard to this type of flying.

They mention using a C-130 variant, the WC-130J, as their primary hurricane tracking aircraft. Like you, I remembered  P3 Orions being used but they didn't seem to be mentioned in their web page.

As you mention, tornadoes and hail would seem to be all but inevitable high-risk aspects of this profession.  They must use advanced radar or something to avoid the worst of these hazards while they are well away from the coast.  Definitely a time to use "continuous ignition"!

[Will]

Basically, it would be interesting to know how much the wind speed varies as one flies across a hurricane at 10,000 feet

Well, that's the real issue. Turbulence has nothing to do with wind speed, per se, but everything to do with variation in velocity over distance (and time).  Even with an eye that's 10 miles across, that's a transit time of several minutes at 250 knots. A change in velocity of several seconds would be no problem for an aircraft. It's when the changes happen in tenths or hundredths of seconds that a problem occurs (namely, the wing or horizontal tail snaps before the change in lift force can be transformed into a change in kinetic energy of the aircraft as a whole). I still bet they can fly through the eye without problems, as long as they avoid areas of massive shear, which are visible on radar (because heavy rain brings heavy downdrafts) and on their Strike Finders (because vertical shear increases the conditions in which lightening is favorable).

Good discussion. We need a lurking hurricane hunter to chime in.

Will

[Hardy Heinlin]

Everyone has seen (video or real) those huge wing bending tests. They bend it extremely, it looks almost like 90° or so.

But to that extreme angles they seem to bend it just slowly. Do they also simulate quick wind velocity changes (fractions of a second) to such big angles?

Edit: I think it doesn't matter. The test already implies the inertia between fuselage and wing. The bending is the inertia per se. Disregard my comment.

|-|ardy

[Jeroen Hoppenbrouwers]

They don't simulate, they just do it.
http://www.youtube.com/watch?v=daOPK07baBw

[Hardy Heinlin]

I didn't mean the AOA of the aircraft, Jeroen. I mean the wing bending test, the bend angle on the lateral axis. Anyway, disregard my comment. The forced bending in the hangar represents the bending caused by the inertia between fuselage and wing in the air.

|-|

[Jeroen Hoppenbrouwers]

If a plane does AoA of 90 degrees, the wings get a pretty hefty updraft, I think? That should bend them a bit...

[Hardy Heinlin]

Ah, OK, now I see what you mean.

That pitch rotation rate on that fighter jet is very quick, indeed. Try this rate on an A340.