Primarily for general aviation discussion, but other aviation topics are also welcome.
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By Harry Brown
#1671985
You do ideally want to ROTATE with glycol or more correctly low foaming propylene glycol covered wings, that is the whole point of anti icing. On jet transport aircraft that require wing tactile tests during the walkround in icing conditions you can still feel the propylene glycol on the wing from the previous deicing. The whole idea is it adheres to the wing to give you holdover time (which is also dependent on precipitation and temperature)

The presence of the fluid on the wing gives you the holdover time- I am not disputing that the majority of the fluid runs back during take off-protection is only needed to ROTATE
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By Iceman
#1672018
alexbrett2 wrote:Interesting, I'd vaguely thought the Seneca gear system was similar to the Arrow - with that as long as you pull the circuit breaker for the hydraulic pump (so that it won't immediately try and pump the gear back up), you can do a manual extension with the gear switch in the up position....


I'll give that a go.

Thanks.

Iceman 8)
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By Flintstone
#1672027
Harry Brown wrote:You do ideally want to ROTATE with glycol or more correctly low foaming propylene glycol covered wings, that is the whole point of anti icing.


I've a sneaking suspicion that you've not actually read my last post, particularly the quote from NASA. Being the kind soul I am I'll pop it up again to save you scrolling back:
Aerodynamic acceptance: to ensure the fluids do not compromise the aerodynamics of the aircraft at the point of take-off; ideally the fluids blow or shear off the wing & tail surfaces during the take-off roll.


In short, above a given airspeed the glycol (or even more correctly ethylene glycol, propylene glycol or di-ethylene glycol) is not required because a) the airflow prevents the precipitation from coming into contact with the surfaces (L/Es excluded) and b) any fluid remaining on the surface itself is a hindrance to laminar flow and therefore a hazard.

Harry Brown wrote:On jet transport aircraft that require wing tactile tests during the walkround in icing conditions you can still feel the propylene glycol on the wing from the previous deicing. The whole idea is it adheres to the wing to give you holdover time (which is also dependent on precipitation and temperature)


Residual fluid on a wing after flight has nothing whatsoever to do with holdover times. It is still on the wing because............ <sigh> look, please go back and re-read my last post carefully. It's all there.

Harry Brown wrote:The presence of the fluid on the wing gives you the holdover time- I am not disputing that the majority of the fluid runs back during take off-protection is only needed to ROTATE


The first part of your sentence is correct. I've not disagreed with that and in fact even gave examples of holdover times. The last part of your sentence is incomplete so it's unclear what you are trying to say.

(I've a fiver that says Harry Brown is a troll account).
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By lobstaboy
#1672031
Flintstone wrote:(I've a fiver that says Harry Brown is a troll account).


I think I can safely speak for all of us when I say, "NO! Really?". ;)

(apologies to the scriptwriters of The Big Bang Theory)
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By Lockhaven
#1672040
Lockhaven wrote:
Harry Brown wrote:Fuselages do not need to be deiced although unbelievably one morning a new deicing crew deiced our fuselage instead of the wings!


That statement is not completely true some types do require the fuselage de-icing.


He hasn't replied to my post yet, maybe he doesn't have an answer. :wink:
By Harry Brown
#1672044
Funny how people on forums always have to get nasty when things don't go their way. Sorry that my opinion may not be yours but am I allowed to express it without being called names
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By Dusty_B
#1672050
Problem is, according to NASA, FAA, EASA and manufacturer guidance, you are wrong! One should not rotate with fluid on the wings. The thick fluid would be a contaminant not much better than the ice it has removed. The minimum rotate speeds are quoted for a very good reason - they might seam irrelevant in a big jet shooting through 120kts before you put down your coffee to pull back on the stick, but for smaller types, we absolutely must know what the speeds are and are required to hold the aircraft on the ground until the minimum rotate speed is reached - which could be 30 kts more than normal (ie, impossible on some types, or requiring a flapless takeoff to prevent wheel-barrowing).
By Harry Brown
#1672052
Can you tell me where these references are you are quoting that say you should not rotate with anti ice fluid on the wings. Ive never heard of one loss of control accident due to excess fluid on the wings at rotate, perhaps you can quote one
By Harry Brown
#1672062
AC No: 135-17
Date: 12/14/94
Initiated
by: AFS-200
Subject: PILOT GUIDE Small Aircraft Ground Deicing

SAE and ISO Type II Fluids.
These fluids contain a minimum of 50 percent glycols and are
considered "thickened" because of added thickening agents that
enable the fluid to be deposited in a thicker film and to remain
on the aircraft surfaces until the time of takeoff.
These fluids
are used for deicing and anti-icing, and provide greater
protection than do Type I fluids against ice, frost, or snow
formation in conditions conducive to aircraft icing on the
ground.

SAE and ISO Type II fluids are designed for use on aircraft with
V sub R greater than 85 knots. As with any deicing or anti-icing
fluid, SAE and ISO Type II fluids should not be applied unless
the aircraft manufacturer has approved their use regardless of
rotation speed.
SAE and ISO Type II fluids are effective
anti-icers because of their high viscosity and pseudoplastic
behavior.
They are designed to remain on the wings of an aircraft during ground operations or short term storage, thereby providing some anti-icing protection,

but to readily flow off the wings during takeoff.

When these fluids are subjected to shear
stress, such as that experienced during a takeoff run, their
viscosity decreases drastically, allowing the fluids to flow off
the wings and causing little adverse effect on the aircraft's
aerodynamic performance.


The anti-icing effectiveness of SAE and ISO Type II fluids is
dependent upon the pseudoplastic behavior which can be altered by
improper deicing/anti-icing equipment or handling. Some of the
North American airlines have updated deicing and anti-icing
equipment, fluid storage facilities, deicing and anti-icing
procedures, quality control procedures, and training programs to
accommodate the distinct characteristics of SAE and ISO Type II
fluids. Testing indicates that SAE and ISO Type II fluids, if
applied with improper equipment, may lose 20 percent to 60
percent of anti-icing performance.
SAE and ISO Type II fluids have been in the process of
introduction in North America since 1985. Widespread use of SAE
and ISO Type II fluids began to occur in 1990. Similar fluids,
but with slight differences in characteristics, have been
developed, introduced, and used in Canada.
By Lefty
#1672067
kanga wrote:where I worked in Northern Canada (Snip)
An alternative was to land on floats on a patch of graded snow , kept graded level on a blown snowbank between runway and taxiway at the nearby airport for precisely this purpose.


I worked in that same snowy place as Kanga.
One flying task that I really enjoyed every autumn, was flying the floatplanes ( no wheels) from the lake (just before it froze over) - and landing them on snow at the side of the runway. The technique was the same as a water landing (but with the water rudders raised). You simply had to land as slow as possible, then apply full nose up elevator to prevent the nose of the floats digging in.
The aircraft were then converted to skis for the winter flying season.
In spring, we did the reverse. The aircraft was lifted and the floats were refitted. Next, the aircraft and floats were mounted on a makeshift trolley. (With castoring front wheels). The trolley allowed you to taxi to the runway and complete your takeoff run. Then as you lifted off, the trolley would detach and roll to stop, whilst I would fly away to land on the water down on the lake.

I wonder if they still do the same these days, or whether Health and Safety has forced them to buy some massively engineered alternative?
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By Flintstone
#1672081
With the infinetisimal chance that Harry is for real...


Harry Brown wrote:Can you tell me where these references are you are quoting that say you should not rotate with anti ice fluid on the wings.


lobstaboy wrote:https://aircrafticing.grc.nasa.gov/2_5_10_1.html


lobstaboy beat me to it. Actually, no he didn't. He nicked my bl00dy link! :D

Nobody has posted that you should not rotate with AI fluid on the wings. What has been posted is that having it there after Vr is not ideal, that is why the manufacturers design it to shear off. They just can't manage to make it so that it ALL comes off.

Just think about it for a moment without throwing a Kevin. Can ice/snow/hail etc adhere to the upper and lower surfaces of a wing while the airflow is keeping them from actually touching the surface? Then ask yourself this. If the precipitation cannnot touch and adhere to the wing why would you want to keep glycol on that wing knowing that it is detrimental to the aerodynamic performance?

Harry Brown wrote:Funny how people on forums always have to get nasty when things don't go their way. Sorry that my opinion may not be yours but am I allowed to express it without being called names


An opinion is not fact. In aviation incorrect facts can get people killed (the only reason I'm continuing with this).

You've had links, quotes and advice from people who use these procedures daily. If those aren't enough then I recommend these.

https://www.tagaviation.com/en/tag-glob ... perations/

https://www.tagaviation.com/en/tag-glob ... anagement/


Troll or instructor, either way ahm oot.
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By Awful Charlie
#1672085
I'm sure there's significant sections of both Harry's and Flinty's posts that are correct, but it's a case of picking and choosing the right bits, which as someone with vastly less experience than either of them does present a bit of a challenge! I do understand that take off with glycol on the lift surfaces is acceptable in certain situations though, but I'm equally prepared to accept there are situations and combinations which make it a total no-go.

As some of you know, I bowl about in a FIKI SEP and haven't fallen out of the sky yet with this one - that has included launching in sub-zero into the murk, and for which I've followed the PoH AFMS instructions, which are pretty much "on and active before takeoff". I can't say I've looked at what is flowing over the wings during the take off roll (I've got other priorities), but I know in the cruise the TKS fluid can be observed rippling its way over the top surface of the wings, and TKS fluid is 85% glycol. My pre-take off departure check will include that it is visibly running over the wing roots from the prop blast, that the screen is getting a right mess due to the prop slinger, which also means a certain amount is going over the engine, as well as down the air induction over the air filter, and even into the heater muff. The last of those does create a bit of a pong, but isn't visible nor sets off a CO alarm, but clears quickly once airborne.
Back to the original nest I stirred up with the suggestion of glycol as a ground deicing agent, I still believe you're ok with neat glycol added to IPA (particularly if squeegeed off before flight), as it is the bigjet holdover fluids include a thickening agent
https://aircrafticing.grc.nasa.gov/2_3_3_1.html includes
...Type II and IV fluids add thickening agents to increase viscosity ...Type III fluids also contain thickening agents ...
which costs extra.

If however your source of glycol is from jet "surplus", you'll have to do your own research and risk assessment
By Harry Brown
#1672086
You still cant reply without making a snide comment can you? Your the reason that people don't use forums.

I understand what you say is fact and what I say is opinion but if this forum is now limited to only facts I can forsee a problem, can you?

Your link says
De/anti-icing fluids are designed to flow or shear off during the take-off roll so that your wing and other critical surfaces are clean for takeoff. For some aircraft, when a thickened Type II, III or IV fluid is applied, an increase in takeoff speeds (V1 & Vr) is required to ensure that the fluid shears off. Recompute your takeoff or balanced field length, if this is the case.

In active ground icing conditions, you will likely want to (or be required to) use aircraft ice protection systems during taxi and takeoff. Ice protection systems that use engine bleed air may require a reduced takeoff thrust setting and/or simply result in less thrust available. Adjust your takeoff calculations, if applicable.


I said Harry Brown wrote:
Can you tell me where these references are you are quoting that say you should not rotate with anti ice fluid on the wings.

Nowhere in that link quoted above does it say you should not rotate with anti icing fluid on the wings
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