Photo of the Day: LM F-35B Goes Supersonic at Night

All about the Pratt & Whitney F135 and the (cancelled) General Electric/Rolls-Royce F136
  • Author
  • Message
Offline
User avatar

spazsinbad

Elite 3K

Elite 3K

  • Posts: 18001
  • Joined: 05 May 2009, 21:31
  • Location: ɐıןɐɹʇsn∀¯\_(ツ)_/¯
  • Warnings: -2

Unread post13 Feb 2017, 18:34

Photo of the Day: Lockheed Martin F-35B Goes Supersonic at Night
13 Feb 2017 FighterSweep Staff

"A Lockheed Martin F-35B produces ‘Shock Diamonds’ as it goes supersonic during twilight refueling testing."

Photo: https://i2.wp.com/fightersweep.com/wp-c ... rsonic.jpg (43Kb)

Source: https://fightersweep.com/7076/photo-day ... nic-night/

Attachments
f-35-supersonic.jpg
RAN FAA A4G Skyhawk 1970s: https://www.faaaa.asn.au/spazsinbad-a4g/ https://www.youtube.com/channel/UCwqC_s6gcCVvG7NOge3qfAQ/
Offline

indigowarrior9

Enthusiast

Enthusiast

  • Posts: 25
  • Joined: 20 Jan 2017, 21:57

Unread post12 Mar 2017, 07:58

When seeing this massive output of exhaust flames from the F35 engine from a big round and open pipe, I still wonder why anyone calls the F35 a "stealth" aircraft, when it must light up like an X-mas tree on any InfraRed / HeatSeeker sensors out there?

Or does one only speak about the "F35-stealthyness" when referring to her radar cross-section seen head-on, the front of the plane?
Offline

SpudmanWP

Elite 3K

Elite 3K

  • Posts: 6384
  • Joined: 12 Oct 2006, 19:18
  • Location: California

Unread post12 Mar 2017, 08:14

The primary sensor to detect aircraft and engage them is radar, not IR.
"The early bird gets the worm but the second mouse gets the cheese."
Offline

citanon

Enthusiast

Enthusiast

  • Posts: 95
  • Joined: 01 Jul 2015, 21:42

Unread post12 Mar 2017, 09:38

Funny thing about an afterburner - the pilot has the choice of turning it on or not turning it on
....
Offline

wrightwing

Elite 2K

Elite 2K

  • Posts: 2367
  • Joined: 23 Oct 2008, 15:22

Unread post13 Mar 2017, 03:47

indigowarrior9 wrote:When seeing this massive output of exhaust flames from the F35 engine from a big round and open pipe, I still wonder why anyone calls the F35 a "stealth" aircraft, when it must light up like an X-mas tree on any InfraRed / HeatSeeker sensors out there?

Or does one only speak about the "F35-stealthyness" when referring to her radar cross-section seen head-on, the front of the plane?

The F-35 has all aspect signature reduction. By the time an enemy would spot afterburner plumes, they'd already be in visual range. At BVR ranges, the F-35 would be judicious in any afterburner usage, keeping the IR signature low.
Offline
User avatar

ricnunes

Active Member

Active Member

  • Posts: 162
  • Joined: 02 Mar 2017, 14:29

Unread post13 Mar 2017, 13:26

indigowarrior9 wrote:When seeing this massive output of exhaust flames from the F35 engine from a big round and open pipe, I still wonder why anyone calls the F35 a "stealth" aircraft, when it must light up like an X-mas tree on any InfraRed / HeatSeeker sensors out there?

Or does one only speak about the "F35-stealthyness" when referring to her radar cross-section seen head-on, the front of the plane?


Complementing what others already replied to you:

Afterburner is not something that a pilot will usually use. A pilot will "rarely" (or "not often" is perhaps a more accurate use of words) use his/hers aircraft afterburner (this is not only on the F-35 but in all other fighter jets) since afterburners above all have an "insane" fuel consumption which drastically reduces the aircraft's range.
This being said, afterburners are briefly used on certain parts of the flight and only when really needed (and again only briefly). Examples of this could be:
- Taking off on the shortest distance possible, specially when carrying heavy loadouts.
- Breaking the sound barrier and attaining high supersonic speeds (something that again a pilot will only do only for brief periods of time).
- During a dogfight for a fast speed recovery specially after maneuvers where the aircraft bleed too much speed/energy (something to ALWAYS avoid at all times!).

Moreover keep notice that you're looking at the rear of the aircraft. If you look at the front of the aircraft you won't likely see any "exhaust flames" of the afterburner at all even if you're looking at it (frontal arc) with an IRST since the F-35 is also said to have some substantial IR-signature reductions such as having the engine well buried inside the fuselage and the ability to carry cooled fuel on the fuselage fuel cells which surrounds the engine.


Oh and by the way (this one is for the topic's OP), excellent night photo and video of the F-35, thanks for sharing :D
Last edited by ricnunes on 13 Mar 2017, 22:09, edited 1 time in total.
Offline
User avatar

steve2267

Forum Veteran

Forum Veteran

  • Posts: 770
  • Joined: 12 Jun 2016, 17:36

Unread post13 Mar 2017, 19:31

I have long taken notice of the interior of the F-135 exhaust nozzle. I am surprised it is fairly bright white in color. Even on test aircraft that have seen tens or hundreds of hours, the interior of the nozzle is white. It is also fairly thick compared to 4th gen fighter aircraft nozzles (e.g. F110, F100, F404 engines on F-15, F-16, and f-18 aircraft.) In addition, someone recently posted a patent granted to LM depicting airflow around the exterior of the nozzle. And on the rear of the F-35, there is a concentric row of "shark teeth" surrounding, and just forward of, the F-135 engine nozzle. It has been suggested internal cooling airflow is vented overboard here. I can only conclude that some really smart, innovative thermal / thermodynamic engineers took a fresh look at a fighter aircraft's signature, and have performed some nifty thermal design engineering that has resulted in a dramatically decreased thermal signature. Of course, the details are probably fairly classified.

But simply stating "the F-35 has the world's largest heat / IR signature -- just look at the size of its engine!" hardly makes it so.
Offline

bumtish

Senior member

Senior member

  • Posts: 350
  • Joined: 14 Nov 2008, 15:59

Unread post20 Mar 2017, 22:48

Let's take an excerpt of the many answers from the Danish minister of defence to questions from members from the Danish parliament.

Question
This note answers the following questions:
"To what extent are the military advantages of JSF (primarily / exclusively) linked to stealth characteristics, and what the risks are that there are new methods for detection of aircraft will reduce the value of stealth?"

...

The Joint Strike Fighter is doing better than the other two candidates [Super Hornet and Eurofighter] partly because of the aircraft's low radar and thermal signatures ( "stealth" properties), but also because the use of advanced systems and sensors promotes the pilot's tactical overview and ensures the aircraft's survival and a effective mission execution. Thus, it is not only "stealth" attributes that provide one plane's military advantage in task performance. The conditions concerning the F-35 aircraft survivability and mission effectiveness - including the meaning of "stealth" - is classified, but may, at request be presented settlement constituency members.

The future importance of "stealth" in line with technological development It is difficult to say whether the importance of an aircraft made with low radar and heat-characteristics ( "stealth") prospectively will diminish, since this depends on the development of new technologies where the operation and effectiveness at the moment is not known. However, there is today no knowledge of technologies which will completely be able to neglect the effect of "stealth" and this is why the property also in future can be assigned a certain value. It should be noted in this connection, that the latest Russian and Chinese aircraft, which is currently under development, also makes use of "Stealth" technology, so a low radar and thermal signatures are general properties pursued in the development of new combat aircraft.


With the help of Google translate.

http://www.ft.dk/samling/20151/almdel/f ... /index.htm
Offline

mixelflick

Elite 1K

Elite 1K

  • Posts: 1411
  • Joined: 20 Mar 2010, 10:26
  • Location: Parts Unknown

Unread post21 Apr 2017, 15:38

This latest concern about the F-35 (big thermal signature) is yet another example of it's ultimate strength IMO...

EVERYONE under-estimates it

Pilots flying Flankers, Eagles, F-16's, Super Hornets, Mig's etc that expect to jump F-35's (if they can find them) are in for a nasty surprise. I can see an SU-35 pilot believing his own hype and searching frantically with that big PESA radar, only to get lit up by an AMRAAM. Or the same SU-35 making it to the merge only to discover the over the shoulder AMRAAM shot isn't just marketing hype.

So long as they continue to under-estimate it, the F-35 is going to have a field day.
Offline

indigowarrior9

Enthusiast

Enthusiast

  • Posts: 25
  • Joined: 20 Jan 2017, 21:57

Unread post24 May 2017, 10:13

Thanks guys for the feedback on this matter.
Lets skip "my F35 afterburner" remark for now and re-focus on the F35 massive jet-exhaust.

I've seen them taking off and flying on the Dutch open Airforce days in 2017, right beside the F16's (see video below)
- https://www.youtube.com/watch?v=7XeViHEWzLk

The F35 were producing an equal if not greater amount of exhaust-pipe noise and heat then the F-16's.

The primary sensor to detect aircraft and engage them is radar, not IR.

But how about those IR-tracking sensors that most russian fighters have on board? (see 1 on the link below)
- https://farm8.static.flickr.com/7574/28 ... 6026_b.jpg

Will these IR-sensors be able to spot an F-35 engine-exhaust heat signature, in a BVR scenario where they have evaded, deflected (by chaff, flairs, active jamming the incoming missile-seeker-heads) the F-35 incoming missiles... thereby forcing the F-35 to move in closer to the enemy and engage them in a Visual Range air-to-air combat fight?
Offline

bumtish

Senior member

Senior member

  • Posts: 350
  • Joined: 14 Nov 2008, 15:59

Unread post24 May 2017, 10:48

indigowarrior9 wrote:Thanks guys for the feedback on this matter.
Lets skip "my F35 afterburner" remark for now and re-focus on the F35 massive jet-exhaust.

I've seen them taking off and flying on the Dutch open Airforce days in 2017, right beside the F16's (see video below)
- https://www.youtube.com/watch?v=7XeViHEWzLk

The F35 were producing an equal if not greater amount of exhaust-pipe noise and heat then the F-16's.


It is not the plume size or amount of heat that an IR sensor primarily sees. It is mainly the temperature difference between exhaust plume and background, which is likely lower for the F-35 than the F-16, and since spectral radiance drops rapidly with temp, the F-35 should have the advantage here. Lower exhaust temp, mixing with bypass air at exhaust, some shielding by airframe. It all adds up and are good controls on signature.

It doesn't go like "uh oh big engine big thrust => big IR signature"
Offline
User avatar

Dragon029

Forum Veteran

Forum Veteran

  • Posts: 896
  • Joined: 22 Dec 2014, 07:13

Unread post24 May 2017, 11:18

indigowarrior9 wrote:
The primary sensor to detect aircraft and engage them is radar, not IR.

But how about those IR-tracking sensors that most russian fighters have on board? (see 1 on the link below)
- https://farm8.static.flickr.com/7574/28 ... 6026_b.jpg

Like he said, they're not the primary sensor for detecting and tracking aircraft - what you're looking at is an IRST sensor. If you know where a jet is, they can be effective for tracking aircraft at short or medium ranges (they generally max out around 50-100km depending on what part of the target is showing, whereas a good radar can track a conventional fighter from several times that distance).

They have a few problems though:

1. They can't properly judge distance without the use of a laser range finder and no fighter-sized laser range finders don't really work beyond about 20km. If all you have is a direction, then you don't know whether the target is in missile range yet.

2. Older IRSTs and even some newer ones like the Su-35's don't produce an infrared image, they only have a handful of (large and sensitive) "pixels". IRSTs like that are extremely limited in their ability to identify a target - is it a big ballistic missile being launched 300km away or is it a stealth fighter coming head-on from 30km away?

3. They generally can't see well through weather - if the stealth fighter is on the other side of a cloud, it's invisible.

4. In order to scan for targets at their maximum range, they need to zoom in using their optics. Once they do this, they have a tiny field of view (eg, less than 1x1 degree); this in turn makes them very slow to scan the sky. Normally they're instead zoomed out, operating at a shorter range, wider field of view mode until a radar contact gives them an area to zoom in on.

Will these IR-sensors be able to spot an F-35 engine-exhaust heat signature, in a BVR scenario where they have evaded, deflected (by chaff, flairs, active jamming the incoming missile-seeker-heads) the F-35 incoming missiles... thereby forcing the F-35 to move in closer to the enemy and engage them in a Visual Range air-to-air combat fight?

It's very unlikely the F-35 would move in closer; they're never going to be flying solo in a warzone, so if the Su-35 doesn't know where he is, he's going to keep his distance and feed his targeting data to another F-35, or a 4th gen, or a land / sea based anti-air system. If an F-35 is alone in combat against an F-35, either all of his wingmen are dead and he also has no base to return to, or it's occurring in a sector of airspace that nobody really cares about and the F-35 can just simply sneak somewhere else where there are friendlies.
Offline

bojack_horseman

Active Member

Active Member

  • Posts: 164
  • Joined: 02 Jun 2016, 19:51
  • Location: Ireland

Unread post24 May 2017, 13:06

indigowarrior9 wrote:Will these IR-sensors be able to spot an F-35 engine-exhaust heat signature


Maybe, though I wouldn't bet on it.

If a Russian aircraft needs to rely on this then chances are he is already dead.

Here is the sales sheet for the SU-35's IRST system
As you can see below, the specs are for optimal conditions (ie: no clouds) against a SU-30, twin engined with minimal IR suppression.

Against either a Raptor or Lightning where a lot of effort has been taken to suppress IR signatures, the target range will be a magnitude shorter.
As I said, if this is their ace in the hole, then they are already doomed.

This page gives some fascinating insight on the infa-red stealth measures involved..... I think it was created by a poster here.
https://basicsaboutaerodynamicsandavion ... -benefits/

Image

Return to F-35 Engine

Who is online

Users browsing this forum: No registered users and 1 guest