Skyhooks, big watches, lace panties and other aviation myths...

Aviation related only
Message
Author
User avatar
TheGreenGoblin
Chief Pilot
Chief Pilot
Posts: 17596
Joined: Thu Aug 08, 2019 11:02 pm
Location: With the Water People near Trappist-1

Skyhooks, big watches, lace panties and other aviation myths...

#1 Post by TheGreenGoblin » Sun Dec 06, 2020 2:42 pm

Icing...

The rubber de-icing boots bridging myth?
Ice bridging is the idea that if you operate the boots too early, you will stretch the ice but not fracture it. When the boot deflates following the cycle, the stretched ice will remain, with more ice building on top of it. Ergo, the next cycle of the boot will be useless, because the boot will simply expand into the cavity underneath the previously stretched ice. It can be traced back to at least the 1943 edition of Civil Aeronautics Bulletin No. 25, Meteorology for Pilots, which stated that, “If aircraft is equipped with leading edge boot type de-icers, allow ice to form to inch thick, then crack off by inflating de-icers. Use de-icers periodically as ice forms. This prevents ice from forming a pocket in which the boot expands…” The identical phrase is found in Zweng’s Airline Transport Rating textbook from 1947, so it is difficult to know who had actually thought about the idea, and who was copy-and-pasting.

It was enshrined in the FAA Aircraft Icing Handbook as late as 1991, which stated that, “Bridging is the formation of an arch of ice over the boot which is not removed by boot inflation. This can occur if the system is activated too early or too frequently, especially in glaze icing conditions.” The Handbook went on to opine that, “A certain degree of pilot skill is required for safe and effective pneumatic boot operation. Actuation when accreted ice is too thin may result in ‘bridging’ where the formation of ice over the boot is not cracked by boot inflation. Thus, attention is required to judge whether the cycle time continues to be correct as icing conditions change.”

Ice on wing of turboprop

Should you wait to pop the boots until “enough” ice has formed?

Yet there is not a single test conducted in anyone’s icing research wind tunnel that has been able to replicate ice bridging, nor are there any accidents that document ice bridging as a cause or contributory factor. There are precisely two reports in forty years of NTSB data that use the term. To be fair, there are plenty of accidents for which we do not have any specific cause aside from a generalization, or even any pilot accounts, so we don’t know what many of those pilots saw; that said, there are also precisely two reports in the entire NASA Aviation Safety Reporting System that use the term ice bridging. In the FAA Accident and Incident Data System, the term does not appear. Most interestingly, the term is never used in the Transportation Safety Board of Canada’s accident data, nor does it appear in Canada’s Civil Aviation Daily Occurrence Reporting System (CADORS).
https://airfactsjournal.com/2020/11/ice ... on%27t+Die
Though you remain
Convinced
"To be alive
You must have somewhere
To go
Your destination remains
Elusive."

User avatar
Undried Plum
Chief Pilot
Chief Pilot
Posts: 7308
Joined: Sun Jul 22, 2018 8:45 pm
Location: 56°N 4°W

Re: Skyhooks, big watches, lace panties and other aviation myths...

#2 Post by Undried Plum » Sun Dec 06, 2020 3:27 pm

Not at all a myth.

I cocked up boot inflation over the chilly bit of the Nawff Sea en route to/from a Shetland isle and came to regret it. Damn nearly killed mesel' in an Aztec doing that.

What was the lacey panties bit? I don't remember that. Brown Y-fronts, originally Persil-white, is wot I remember.

User avatar
TheGreenGoblin
Chief Pilot
Chief Pilot
Posts: 17596
Joined: Thu Aug 08, 2019 11:02 pm
Location: With the Water People near Trappist-1

Re: Skyhooks, big watches, lace panties and other aviation myths...

#3 Post by TheGreenGoblin » Sun Dec 06, 2020 4:50 pm

Undried Plum wrote:
Sun Dec 06, 2020 3:27 pm
Not at all a myth.

I cocked up boot inflation over the chilly bit of the Nawff Sea en route to/from a Shetland isle and came to regret it. Damn nearly killed mesel' in an Aztec doing that.

What was the lacey panties bit? I don't remember that. Brown Y-fronts, originally Persil-white, is wot I remember.
The lace panties myth is likely to be true too. It was related to me by my AME as he was examining my ears and discovered the plastic stopper from a Bic pen embedded in my ear (I had noticed no irritation in my ear at all). He said he seen weirder things in his time and told me about the airline Captain who was late for his morning medical and who, when he arrived, apologized, as he had a bit of a night on the pop and had overslept. Despite this the medical proceeded normally until he had to drop his trousers and there he was resplendent in a pair of very fetching girly panties. His story was that he had accidently put his girlfriend's knickers on in his rush to get to the medical... Whatever floats your boat man! =))

As for the icing thing, I was always told to let the ice accumulate lest a gap grew between the boots and the icy covering through too frequent inflation.
Though you remain
Convinced
"To be alive
You must have somewhere
To go
Your destination remains
Elusive."

User avatar
Undried Plum
Chief Pilot
Chief Pilot
Posts: 7308
Joined: Sun Jul 22, 2018 8:45 pm
Location: 56°N 4°W

Re: Skyhooks, big watches, lace panties and other aviation myths...

#4 Post by Undried Plum » Sun Dec 06, 2020 5:06 pm

I do wonder how the PC24 drivers manage the rubber boots on the vertical and horizontal stab.

The mainplane leading edges are fired by the coalplace, but the afterburner bitz astern are old-fashioned rubber pufferbitz. How does that work? How does the traindriver monitor that?

Eager minds need to know such stuff. The rest of us simply snore, loudly. Or so I'm told, repeatedly.

Tell me about the bit about lacy panties again, please. I think I've got a carat.

User avatar
TheGreenGoblin
Chief Pilot
Chief Pilot
Posts: 17596
Joined: Thu Aug 08, 2019 11:02 pm
Location: With the Water People near Trappist-1

Re: Skyhooks, big watches, lace panties and other aviation myths...

#5 Post by TheGreenGoblin » Sun Dec 06, 2020 6:05 pm

Undried Plum wrote:
Sun Dec 06, 2020 5:06 pm
I do wonder how the PC24 drivers manage the rubber boots on the vertical and horizontal stab.

The mainplane leading edges are fired by the coalplace, but the afterburner bitz astern are old-fashioned rubber pufferbitz. How does that work? How does the traindriver monitor that?
A combination of bleed air and de-ice boot operation on the bits astern on the PC24 I believe UP. Dual ice detection systems on that very sophisticated hairy plane. Far more complex than the BF Goodrich boots on the PC12... which has come to grief in icing conditions.

http://www.iasa.com.au/folders/Safety_I ... _again.htm
Though you remain
Convinced
"To be alive
You must have somewhere
To go
Your destination remains
Elusive."

Boac
Chief Pilot
Chief Pilot
Posts: 17207
Joined: Fri Aug 28, 2015 5:12 pm
Location: Here

Re: Skyhooks, big watches, lace panties and other aviation myths...

#6 Post by Boac » Sun Dec 06, 2020 6:14 pm

UP wrote: cocked up boot inflation over the chilly bit of the Nawff Sea en route to/from a Shetland isle and came to regret it. Damn nearly killed mesel' in an Aztec doing that.
Reminds me of the Aztec I 'borrowed' from G Rosenbloom at EDI - on a commercial CofA with ADF broken and wing boots so perforated that when I and my tame eng smeared a soap film on it and ran the boots it blew many bubbles. :))

User avatar
Undried Plum
Chief Pilot
Chief Pilot
Posts: 7308
Joined: Sun Jul 22, 2018 8:45 pm
Location: 56°N 4°W

Re: Skyhooks, big watches, lace panties and other aviation myths...

#7 Post by Undried Plum » Sun Dec 06, 2020 6:22 pm

Ah hivnae got the dosh tae buy one and run of they things onywhy.

**** gorgeous though they are.

PC24s ought to be issued to puir folk like me like sacks o' tatties. I'd even vote for SNbloodyP if they'd promise me one of thane fokkinthjings.

User avatar
Undried Plum
Chief Pilot
Chief Pilot
Posts: 7308
Joined: Sun Jul 22, 2018 8:45 pm
Location: 56°N 4°W

Re: Skyhooks, big watches, lace panties and other aviation myths...

#8 Post by Undried Plum » Sun Dec 06, 2020 6:46 pm

Boac wrote:
Sun Dec 06, 2020 6:14 pm
G Rosenbloom at EDI - on a commercial CofA with ADF broken and wing boots so perforated that when I and my tame eng smeared a soap film on it and ran the boots it blew many bubbles.
Am I allowed to say antiSemitic words like ****q in the context of that ****q!?

If so: he was, and behaved like one, a ****q.

****q!. Him, not you, dear boy, Boac.

John, of Embra Air Taxi, was completely different. An excellent fellow, though he did shag one of my best girlfriends. I was reluctant to forgive him for that until an Ash tree fell on him and killed him while he was trying to cut it down on his estate at Ratho.

Muvver Nature is a right old bitch.

Where were we in the story about lacy panties? Please forgive me, I do sometimes lose the plot. Carry on. please.

User avatar
TheGreenGoblin
Chief Pilot
Chief Pilot
Posts: 17596
Joined: Thu Aug 08, 2019 11:02 pm
Location: With the Water People near Trappist-1

Re: Skyhooks, big watches, lace panties and other aviation myths...

#9 Post by TheGreenGoblin » Sun Dec 06, 2020 6:54 pm

Undried Plum wrote:
Sun Dec 06, 2020 6:46 pm

Where were we in the story about lacy panties? Please forgive me, I do sometimes lose the plot. Carry on. please.
I can say no more than I said in post #3 UP. ;)))
The lace panties myth is likely to be true too. It was related to me by my AME as he was examining my ears and discovered the plastic stopper from a Bic pen embedded in my ear (I had noticed no irritation in my ear at all). He said he seen weirder things in his time and told me about the airline Captain who was late for his morning medical and who, when he arrived, apologized, as he had a bit of a night on the pop and had overslept. Despite this the medical proceeded normally until he had to drop his trousers and there he was resplendent in a pair of very fetching girly panties. His story was that he had accidently put his girlfriend's knickers on in his rush to get to the medical... Whatever floats your boat man! =))
Though you remain
Convinced
"To be alive
You must have somewhere
To go
Your destination remains
Elusive."

User avatar
Undried Plum
Chief Pilot
Chief Pilot
Posts: 7308
Joined: Sun Jul 22, 2018 8:45 pm
Location: 56°N 4°W

Re: Skyhooks, big watches, lace panties and other aviation myths...

#10 Post by Undried Plum » Sun Dec 06, 2020 7:12 pm

i'm in twubble Mister Gwimsdale.

I'm in twubble Mr Gwimsdale!

Help me, Mr Gwimsdale!

User avatar
CharlieOneSix
Chief Pilot
Chief Pilot
Posts: 5004
Joined: Thu Aug 27, 2015 12:58 pm
Location: NE Scotland
Gender:
Age: 79

Re: Skyhooks, big watches, lace panties and other aviation myths...

#11 Post by CharlieOneSix » Sun Dec 06, 2020 8:57 pm

Back in my day there were no helicopter rotor deicing systems as there are now. On the Bell 214ST (my avatar) we had nice fat 29 inch chord rotor blades which built up their own heat through friction in flight and enabled us to get the first helicopter moderate icing clearance. We hung quite a bit of ice on the fuselage during trials but the blades remained relatively clear.

When the icing clearance was subsequently issued we could stay in icing conditions as long as the torque didn't increase by more than 10% - we normally cruised at around 70% torque. During the trials we got to a 17% rise but then we started to get asymmetric shedding of rotor blade ice which was 'rather' uncomfortable. A couple of years ago I posted some photos taken during the icing trials at viewtopic.php?p=156055#p156055. Re big watches, I think we deserved some after that trial - it got the pulse rate up at times!
The helicopter pilots' mantra: If it hasn't gone wrong then it's just about to...
https://www.glenbervie-weather.org

User avatar
TheGreenGoblin
Chief Pilot
Chief Pilot
Posts: 17596
Joined: Thu Aug 08, 2019 11:02 pm
Location: With the Water People near Trappist-1

Re: Skyhooks, big watches, lace panties and other aviation myths...

#12 Post by TheGreenGoblin » Tue Dec 08, 2020 11:48 pm

To the helicopter cognoscenti here, are there any helicopters that have heated rotors. I guess I could look it up but would rather hear form those who know.
Though you remain
Convinced
"To be alive
You must have somewhere
To go
Your destination remains
Elusive."

G-CPTN
Chief Pilot
Chief Pilot
Posts: 7594
Joined: Sun Aug 05, 2018 11:22 pm
Location: Tynedale
Gender:
Age: 79

Re: Skyhooks, big watches, lace panties and other aviation myths...

#13 Post by G-CPTN » Tue Dec 08, 2020 11:53 pm

TheGreenGoblin wrote:
Tue Dec 08, 2020 11:48 pm
To the helicopter cognoscenti here, are there any helicopters that have heated rotors.
Fairey Rotodyne?

User avatar
TheGreenGoblin
Chief Pilot
Chief Pilot
Posts: 17596
Joined: Thu Aug 08, 2019 11:02 pm
Location: With the Water People near Trappist-1

Re: Skyhooks, big watches, lace panties and other aviation myths...

#14 Post by TheGreenGoblin » Tue Dec 08, 2020 11:58 pm

G-CPTN wrote:
Tue Dec 08, 2020 11:53 pm
TheGreenGoblin wrote:
Tue Dec 08, 2020 11:48 pm
To the helicopter cognoscenti here, are there any helicopters that have heated rotors.
Fairey Rotodyne?
I guess... :-bd

Hot bleed air.
Though you remain
Convinced
"To be alive
You must have somewhere
To go
Your destination remains
Elusive."

User avatar
CharlieOneSix
Chief Pilot
Chief Pilot
Posts: 5004
Joined: Thu Aug 27, 2015 12:58 pm
Location: NE Scotland
Gender:
Age: 79

Re: Skyhooks, big watches, lace panties and other aviation myths...

#15 Post by CharlieOneSix » Wed Dec 09, 2020 12:41 am

Yes, I’m sure there are others but the AW189 and AW139 have a FIPS system - Full Icing Protection System - which has electrically heated blades. Don’t quote me as I’m not in the know any more but I believe a separate generator is required for FIPS. These types can have LIPS - Light Icing Protection System - which doesn’t have an additional generator and doesn’t have heated blades.
The helicopter pilots' mantra: If it hasn't gone wrong then it's just about to...
https://www.glenbervie-weather.org

User avatar
CharlieOneSix
Chief Pilot
Chief Pilot
Posts: 5004
Joined: Thu Aug 27, 2015 12:58 pm
Location: NE Scotland
Gender:
Age: 79

Re: Skyhooks, big watches, lace panties and other aviation myths...

#16 Post by CharlieOneSix » Wed Dec 09, 2020 2:01 pm

A search threw up this 2016 press release from Leonardo. It seems LIPS is similar to the limited icing clearance we had in my day where on offshore flights in icing conditions you had to have 500ft of positive air above the sea which was available if you needed to get out of icing - or 500ft available above safety altitude elsewhere. With FIPS it appears that limitation is removed.

https://www.leonardocompany.com/en/pres ... aw189-2016
The helicopter pilots' mantra: If it hasn't gone wrong then it's just about to...
https://www.glenbervie-weather.org

User avatar
ian16th
Chief Pilot
Chief Pilot
Posts: 10029
Joined: Fri Aug 28, 2015 9:35 am
Location: KZN South Coast with the bananas
Gender:
Age: 87

Re: Skyhooks, big watches, lace panties and other aviation myths...

#17 Post by ian16th » Wed Dec 09, 2020 2:28 pm

TheGreenGoblin wrote:
Tue Dec 08, 2020 11:58 pm
G-CPTN wrote:
Tue Dec 08, 2020 11:53 pm
TheGreenGoblin wrote:
Tue Dec 08, 2020 11:48 pm
To the helicopter cognoscenti here, are there any helicopters that have heated rotors.
Fairey Rotodyne?
I guess... :-bd

Hot bleed air.
From someone who should keep out of this thread, but has had his interest piqued.

Were not the blade tips of the rotor travelling at supersonic speed? I have memories of this being the reason for its noise generation.

If so, would ice have any chance of forming?
Cynicism improves with age

k3k3
Capt
Capt
Posts: 1492
Joined: Thu Sep 10, 2015 9:44 pm
Location: In the Transit Lounge

Re: Skyhooks, big watches, lace panties and other aviation myths...

#18 Post by k3k3 » Wed Dec 09, 2020 2:40 pm

The Rotodyne was so loud because in vertical and transitionig to level flight the tip jets were effectively afterburners, the bleed air had fuel injected in the tip jets. Once it was flying along lift was produced by the wing and the rotor acting as an autogyro.

User avatar
ian16th
Chief Pilot
Chief Pilot
Posts: 10029
Joined: Fri Aug 28, 2015 9:35 am
Location: KZN South Coast with the bananas
Gender:
Age: 87

Re: Skyhooks, big watches, lace panties and other aviation myths...

#19 Post by ian16th » Wed Dec 09, 2020 3:40 pm

Oh!

I said I shouldn't have asked. Way out of my area of expertise.

Why did I have memories of supersonic rotor tips?
Cynicism improves with age

k3k3
Capt
Capt
Posts: 1492
Joined: Thu Sep 10, 2015 9:44 pm
Location: In the Transit Lounge

Re: Skyhooks, big watches, lace panties and other aviation myths...

#20 Post by k3k3 » Wed Dec 09, 2020 6:51 pm

Harvard propeller? That had supersonic tips.

Post Reply