Fighter jets and FIKI

[Big Pratt]

This subject came up in a conversation: do fighter jets have any de-icing/anti-icing?

I know that they can melt it away with friction heating, but it's hard to do a non precision pushing 400kts... not to mention the miles it would take to slowdown to gear extension speed. Especially with a quarter inch of rime on the canopy.

AuxBattOn (or others in the "RCAF"), please enlighten us on capabilities/procedures.


Fly Safe!
BP

[BigglesNBella]

Wow that's a really good question... posting here to make sure I notice it for when someone answers!

[Darkwing Duck]

Not familiar at all with the de-icing capabilities of a fighter but can I guess it would be bleed air that is used?

[Rockie]

There is engine anti-ice but nothing on the airframe. Most of the time they are going too fast for it to be an issue even during the initial stages of an instrument penetration from 20,000 feet. Slowing for final approach is very easy with speedbrakes, and from that point the exposure time is not enough to be a problem. Fighters are also capable of much greater lift generation (AOA) than typical civilian aircraft which also mitigates the risk. Landing at higher speeds if necessary is also not usually an issue. If it ever is a problem pushing the throttles up takes care of it nicely, and as mentioned in another thread speed limits do not apply to military aircraft.

[Hawkerflyer]

Interesting question!
I know Dausault Falcon's do not have any ice protection on the tail. Its funny because not one person can give me an explination as to why. I have asked demo pilots, Flight Safety and Dausault enginieers. Answers is...its just not needed. Its the only aircraft ive flown with no tail anti/deice capabilities.

[RVgrin]

posting here to make sure I notice it for when someone answers!

You can subscribe to a topic without posting. Click on "Subscribe Topic".

[ybwflyguy]

Interesting question!
I know Dausault Falcon's do not have any ice protection on the tail. Its funny because not one person can give me an explination as to why. I have asked demo pilots, Flight Safety and Dausault enginieers. Answers is...its just not needed. Its the only aircraft ive flown with no tail anti/deice capabilities.

Neither do any Boeings that i'm aware of...I guess it was just never a problem during icing approval. There are also plenty of aircraft that have protection on the horizontal stab, but not the vertical. I assume they test the hell out of it, and if there isn't much accumulation they leave unprotected.

[Moose47]

G'day BP

Just one point to make. Unfortunately the R.C.A.F. (Royal Canadian Air Force) ceased to exist effective the 1st of February 1968 thanks to the Liberals and Bill C-243 the 'Canadian Forces Reorgnaization Act, )-:

[Big Pratt]

Moose47, I know, hence the "", but to me it will always be the RCAF.
Somewhere in the big CY(M) in the sky, there's a squadron of Arrows practicing intercepts


How do you fighter drivers deal with ice on the canopy?

BP

[mbav8r]

No tail anti-icing on the RJ/CRAs either,
"Increasing the airspeed by at least 100 KIAS at low altitudes will affect a TAT rise of an average of 8°C which may shed ice formations that could have formed on non-deiced portions of the airframe"

[iflyforpie]

Just a guess but I think the canopy gets pretty toasty as well. Usually the ultimate speed limit of an aircraft has a lot to do with the canopy design. Ever wonder why the Arrow and SR-71 have those ugly divided windscreens, the F-14 has that huge flat frame of glass, while the Viper has a nice one-piece bubble?

Technology has increased over the years enabling the F-22 to have a a one-piece bubble, but I still would imagine the heat and stress is considerable at supersonic.

[Rockie]

Windscreens have defogging on the inside, and a bleed air de-icing and rain removal system for a portion of the external windscreen. The canopies themselves don't seem to need anything but the ambient air flow of the cockpit.

I've never heard of the windscreen being a limit on the top speed of a fighter. The 104 did have an inlet temperature limit of around 800 degrees I think, which was a limiting factor on speed. When the big red light on the panel came on you slowed down or else. Mostly it's a muscle over drag problem and how an aircraft overcomes the airflow into the engine.

An engine will not accept supersonic air so the intakes have to have mechanisms or an inherent design to slow it down before it reaches the compressors. The SR-71 had those BIG cones that moved in and out. The F4 has a splitter plate that moved the shock wave around so that the air coming in had to pass throught it thus slowing it down. The F-15 has the same concept with the intake box.

The F16 and F18 overcome the problem with clever intake design, but since they are fixed they only work up to a certain speed.

[SAR_YQQ]

and as mentioned in another thread speed limits do not apply to military aircraft.

Be careful here - military aircrew are not subject to the CARs - however we still adhere to our own set of flying rules, one of which is airspeed restrictions below 3000' AGL etc. The only time that these airspeed rules are not in play is in military airspace (ie MTCA).

[teacher]

I asked a fighter pilot that once after landing in Thunderbay in some pretty good icing conditions. I said "how do you fly through ice without deicing equipement?" He pointed his hand up, than down to say straight up through it or straight down

[Rockie]

and as mentioned in another thread speed limits do not apply to military aircraft.

Be careful here - military aircrew are not subject to the CARs - however we still adhere to our own set of flying rules, one of which is airspeed restrictions below 3000' AGL etc. The only time that these airspeed rules are not in play is in military airspace (ie MTCA).

Of course...CFP100 and specific group orders (if they still call them that). Back in the day we never had any restriction on speed except the big one. Supersonic was generally discouraged anywhere outside military airspace. Things may have changed, but I doubt the fighter community today is required to maintain 250/10000 or 200/3000 when in civilian airspace.

[iflyforpie]

Windscreens have defogging on the inside, and a bleed air de-icing and rain removal system for a portion of the external windscreen. The canopies themselves don't seem to need anything but the ambient air flow of the cockpit.

I've never heard of the windscreen being a limit on the top speed of a fighter. The 104 did have an inlet temperature limit of around 800 degrees I think, which was a limiting factor on speed. When the big red light on the panel came on you slowed down or else. Mostly it's a muscle over drag problem and how an aircraft overcomes the airflow into the engine.

An engine will not accept supersonic air so the intakes have to have mechanisms or an inherent design to slow it down before it reaches the compressors. The SR-71 had those BIG cones that moved in and out. The F4 has a splitter plate that moved the shock wave around so that the air coming in had to pass throught it thus slowing it down. The F-15 has the same concept with the intake box.

The F16 and F18 overcome the problem with clever intake design, but since they are fixed they only work up to a certain speed.

Sorry, I was thinking more in terms of design requirements rather than operational limitations, which are usually the engines either because they can't slow the air down enough or the NGV temps get too high (as a function of compressor inlet/discharge temp). But I wouldn't think interior defog alone would be hot or powerful enough to remove ice (the Lears use raw bleed air on the outside for ice protection).

Given that you usually see normal shockwaves on the canopy during high speed, high humidity passes, would that not also generate a lot of heat?

[Rockie]

You're right about the defog not clearing ice, it only keeps fog off the inside as the name implies. There is hot bleed air fed to the outside of the windscreen in case you need to deice. In the CF18 it is 20 inches left of centre to 9 inches right.

At high speed of course it isn't required because of increased TAT.

[AuxBatOn]

Rockie,

The rules is the same as the civilian rule now. Even for us. However, there is a caveat that says that you SHALL adhere to AOIs recommended speeds for the flown procedure. 350 on departure, 280 on an IFR descent, 220-240 on an IFR base leg.

I never had any issues doing this in civilian airspace. If they need me to slow down they tell normally tell me or ask me what's the lowest speed I can maintain. I obviously try to acomodate within reason.

Supersonic: North of Boom Line, pretty much anywhere. South of boom line, above 30K in MFAs, above 30K in controlled airspace with ATC approval. As long as you're not pointing at a civilisation. Obvisouly, Live missions and emergencies: anytime.

[Hedley]

I've never heard of the windscreen being a limit on the top speed of a fighter

IIRC the F-4 had an airspeed limitation dictated by windscreen heating, as does the F-16 with respect to it's canopy. I can dig them up if anyone really cares.

"how do you fly through ice without deicing equipement?"

I think I've mentioned here before that my father flew T-33's all over Europe, North Africa and Canada in all conditions. The squadrons generally had one for hood training that didn't get any maintenance - the oleos were always flat, etc. Anyways, he drove T-33's everywhere like a pickup truck. Never had any problems with icing as long as he kept the speed up over 300 knots.

One day, flying Sabres in Europe with 1 wing in the 1950's, he made the mistake of being the only reasonably sober pilot in the mess, which he later drove a steamroller into, but that's another story. He was sent to Geneva to pick up some medicine for some emergency. So off in the neglected T-33 he goes. He lands and parks in front of the airport terminal, enraging the local bureaucracy. Jumps out of the T-33, grabs the medicine and runs back to the T-33 ahead of an enraged wavefront of bureaucrats. Quill shaft doesn't break, and off he goes. Unforunately he gets the IFR departure clearance from hell. Fly to this beacon at this altitude, then turn to this heading and that altitude .... this drones on for quite a while, and poor old Dad doesn't even have a pencil. But his ears perk up when he hears that above FL200 he is cleared enroute, and he reads that back. Taxis out, throttle forward. Gear up and accelerate level as fast as that poor little T-33 would go in ground effect. Pull vertical at the end of the runway, and capping off, called through FL200 which was an outrageous fib.

Just another day for a Sabre pilot in 1 wing.

[Shadowfax]

First off - no fighter time

However if we're gonna tell stories second hand.....

One of my first instructors was a Widow driver. As I recall it even though Canucks called it an AW interceptor it had no anti-ice other than performance (as mentioned) However, he said the faster you flew the quicker it would ice up so continued flight in known ice was a big NO-NO. Basically as already discussed anti ice was a vertical solution.

However, I know that MJ basically shuts down if there is any forcast icing. Is there a difference between the Hawk and Dog whistles vs the 18?

[Hedley]

the faster you flew the quicker it would ice up

No. As an extreme example, look at the X-15. It never suffered from any icing problems. In fact, at mach 6, it would melt it's leading edges off. Look at all the problems they had with heat with the SR-71.

[Gannet167]

Rate of catch increases with speed - you'll accumulate more ice by going faster. This works up until the temperature rise on the airframe due to friction heating is sufficient to melt ice.

The big jets and many others like the CRJ don't have tail icing because the tail has enough pitch authority that it can sufficiently maintain control of the aircraft even with ice. If I remember right, for certification they attach 3" ice shapes to the leading edge of the tail, shaped like horns, and fly the plane to Vref-5 at full flap and max landing weight and fwd C of G. The wings on these aircraft are kept quite clean with the bleed air wing anti-ice. They're normally in the flight regime where ice is a problem for only a few minutes. I suppose if you were in a hold for an hour in severe icing, it might be a different story.

[iflyforpie]

With jet with rear engines, there is also the risk of shedding ice being ingested into the intakes. I believe there was an MD-80 that was brought down this way from frost accumulation from cold-soaked fuel tanks on the top of the wing.

On the good ol' 727, the top VHF antenna was heated because it was right in front of the #2 inlet. It was also critical to make sure there was no snow or ice on the top of the fuselage.

[Gannet167]

Although I find it hard to believe, a seasoned 727 pilot confirmed to me that ice accumulating from a leaking lav dump valve could break off and not just cause damage - but take the entire #3 engine off.

[RVgrin]

Although I find it hard to believe, a seasoned 727 pilot confirmed to me that ice accumulating from a leaking lav dump valve could break off and not just cause damage - but take the entire #3 engine off.

That's when the sh*t really hits the fan.