What is this system/sensor? Underside UK military aircraft

[e8n2]

20 hours ago, Antti_K said:

Hello Dave,

 

and thank you for all the information. We were flying Aerogeophysical survey missions mainly on areas where there was no snow. On the other hand, some missions in Africa were flown over desert.

 

A couple of months ago I got home from the local hobby shop carrying the Italeri 1/48 scale TR-1 kit. I will build it as an U-2R. I'm still looking for information about the camera bay and camera equipment. Can you help me with that?

 

Cheers,

Antti

Can't really help you there as those were not part of my systems.  The only difference between a U-2R and TR-1A was the serial number.  There were a few minor variations between mainly the early build U-2Rs and the later build U-2Rs and TR-1As.  Those were all internal.  All of the surviving U-2R and TR-1A airframes have had new engines fitted and are all designated as the U-2S.  I don't know for sure which engine went in and there possibly may have been a modification done to the intakes for the increased airflow of the newer engines.  AFAIK, the TR-1Bs also got the new engine and if the past is any indicator, they would be designated (incorrectly per the regs) as the U-2ST.  As I remember it, Q Bay is right behind the cockpit.  Behind that was E Bay, and that was where the INU was located along with some other avionics.  The insides of the bays are painted chromate yellow, as is the intake trunking after about the first 6 - 12" of the intake.  I had to refer to the Aerofax Minigraph #28 to refresh my memory on which bay was where (it's been over 35 years since I last worked on them).  The minigraph also talks a bit about the cameras, but I imagine that those were mostly the cameras carried by the early A and C model deuces.

Later,

Dave

[wellsprop]

Well this has turned into a nerdy navigation systems discussion - I love this stuff! 

[Head in the clouds.]

On 9/3/2021 at 10:42 AM, dov said:

There are so many, most modeller have seldom a clue what is all the antennas, probes etc!

This topic should we blow up and widen!

I think that would be a very useful resource that could also be sub sectioned into WW2/postwar and modern, also including helicopters. It was also add to the interest level of builds as I have a Merlin in the pipeline which is festooned with sticky out bits of which I have a complete lack of knowledge but which I would love to learn about.  

[dov]

Ok, so we will see what I can do:

My suggestion is: If you have any request to externals, no matter what, let me know & start a topic! I will suport & push! I know a lot and have lots of photos from my own collection. So, it is up to you. 

Happy modelling 

[Wez]

The Doppler 71/72 system had a Y (71) or X (72) shaped beam pattern and was used to calculate drift, it wouldn't give you a bearing or heading, just tell you what your groundspeed was and whether you were drifting left or right, the Doppler 71 used on helicopters was designed to work with groundspeeds up to 220kts, I never worked on Doppler 72 equipped platforms but seeing as they're fast jets I'm guessing it calculated much higher groundspeeds.

 

The Doppler was hooked up to a nav computer that had the starting point lat/long set and used a combination of air data (e.g. pitot-statics (or wind and p**s as my instructors referred to it))/gyro magnetic compass heading data and if available, another data source to resolve position reasonably accurately (although nowhere as accurately as current systems).  When I first started working on helicopters we used the Decca 19 system linked into the Decca Navigator, itself the progeny of the wartime Gee system.  If Decca navigator wasn't available Omega or even LORAN was used.  These are all parabolic navigation systems which use crossing beams to resolve your position...   ...ish.  These systems began getting superseded by GPS in the early 90's.

 

Basically, Doppler based systems knew your starting point, knew which direction you'd gone in and for how long, what your groundspeed was, what your drift was and would, especially if helped by another external system, hopefully tell you where you were, give or take.

 

The system was used on helicopters throughout the 70's through the 2010's, I'm at a loss to explain why Antti's systems didn't work. it would seem to be the ideal thing for the scenario he describes (bearing in mind British military helicopter pilots would get a nosebleed flying above 250ft).

 

As mentioned, it didn't work so well over the sea/snow/ice, some nav computers applied a fudge factor when alerted to those conditions.

[dov]

It is very interesting.

To hear about the pre GPS navigation. Me I have the knowledge from the very old days,  as the 1930 and 1940. As hobby just. Mathematicaly and geometricaly interest.

Today I recognize the GPS bound navigation as a risk. Abandoning and loosing the ability to work without it as system B, in case if.

Happy modelling 

[e8n2]

9 hours ago, dov said:

It is very interesting.

To hear about the pre GPS navigation. Me I have the knowledge from the very old days,  as the 1930 and 1940. As hobby just. Mathematicaly and geometricaly interest.

Today I recognize the GPS bound navigation as a risk. Abandoning and loosing the ability to work without it as system B, in case if.

Happy modelling 

I would think that if there was any concern as to whether or not GPS was throwing off the current present position, then, if still possible, trying to get a TACAN update for the INS would be the thing to do.  I have read numerous stories about GPS getting you into dead end roads or the wrong road altogether when you are driving in your car, but not about problems with the airborne version.  The Air Force doesn't even train navigators anymore, they just let the pilots take care of things with INS and GPS.  I just hope that they have their aircraft systems hardened against an EMP (Elecetro-Magnetic Pulse) or it will be back to looking for the "iron compass" days again.

Later,

Dave

[junglierating]

On 9/3/2021 at 2:54 PM, Giorgio N said:

 

On carriers the INS of the aircraft was usually aligned by slaving it to the ship's own system. In this way the two were aligned the same way,

Back in the day for a young greenie on board ARK that was one of my jobs...Boardman....used to take the lat long and track then hold it up in front of the cockpit and the pilot used to push the figures in to the TANS unit ....so agricultural 

[junglierating]

13 hours ago, e8n2 said:

I would think that if there was any concern as to whether or not GPS was throwing off the current present position, then, if still possible, trying to get a TACAN update for the INS would be the thing to do.  I have read numerous stories about GPS getting you into dead end roads or the wrong road altogether when you are driving in your car, but not about problems with the airborne version.  The Air Force doesn't even train navigators anymore, they just let the pilots take care of things with INS and GPS.  I just hope that they have their aircraft systems hardened against an EMP (Elecetro-Magnetic Pulse) or it will be back to looking for the "iron compass" days again.

Later,

Dave

I think that is why the aircrewman still use paper maps and mental arithmetic just in case the GPS and the moving map goes tits up 

[Wez]

45 minutes ago, junglierating said:

I think that is why the aircrewman still use paper maps and mental arithmetic just in case the GPS and the moving map goes tits up 

Mental arithmetic and a crewman, there's a reason we referred to them as dopes on a rope!

 

[junglierating]

1 hour ago, Wez said:

Mental arithmetic and a crewman, there's a reason we referred to them as dopes on a rope!

 

I think RN RM aircrewman might take umbridge with that 🤔😆

[Wez]

6 minutes ago, junglierating said:

I think RN RM aircrewman might take umbridge with that 🤔😆

Good, they may need to take their boots off to do the sums unlike a RAF crewmen.

[junglierating]

32 minutes ago, Wez said:

Good, they may need to take their boots off to do the sums unlike a RAF crewmen.

🥱😄

[e8n2]

10 hours ago, Wez said:

Mental arithmetic and a crewman, there's a reason we referred to them as dopes on a rope!

 

At Travis we usually referred to the Loadmaster as a dope on a rope.  He or she was usually the last one on the plane doing a quick outside check with a long cord hooked up to their earphones and mics!

Later,

Dave

[e8n2]

9 hours ago, junglierating said:

I think RN RM aircrewman might take umbridge with that 🤔😆

We always referred to the Marines as Jarheads.  Did you guys have the same or similar name for the Royal Marines?

Later,

Dave

[Wez]

1 hour ago, e8n2 said:

At Travis we usually referred to the Loadmaster as a dope on a rope.  He or she was usually the last one on the plane doing a quick outside check with a long cord hooked up to their earphones and mics!

Later,

Dave

 

Similar in the RAF.

 

1 hour ago, e8n2 said:

We always referred to the Marines as Jarheads.  Did you guys have the same or similar name for the Royal Marines?

Later,

Dave

 

Booties, worked with them several times, they're a really good bunch.

 

@wellsprop, apologies for the thread drift, any Doppler indicator would be indicating hard starboard or hard port drift.  Regarding your degree course, did it include modules on avionics and other systems or did it concentrate on structures and aerodynamics?

 

Going back to the Doppler antenna, it would be quite a common fit on British aircraft from the 1970's onwards, it was fitted on Queenies (Sea King), Puma, Tonka and Sea Harrier as you've seen.  I'm guessing the Doppler was used to address the drift issues on the old gyro/accelerometer based inertial nav systems.

[junglierating]

1 hour ago, Wez said:

 

Similar in the RAF.

 

 

Booties, worked with them several times, they're a really good bunch.

 

@wellsprop, apologies for the thread drift, any Doppler indicator would be indicating hard starboard or hard port drift.  Regarding your degree course, did it include modules on avionics and other systems or did it concentrate on structures and aerodynamics?

 

Going back to the Doppler antenna, it would be quite a common fit on British aircraft from the 1970's onwards, it was fitted on Queenies (Sea King), Puma, Tonka and Sea Harrier as you've seen.  I'm guessing the Doppler was used to address the drift issues on the old gyro/accelerometer based inertial nav systems.

Still fitted ....same Thales  analogue doppler fitted to Merlin MK2 ....the Mk4 now has the Selex digital doppler.

 Bootnecks ....good at Queues....ask @bootneck 😆😆😆😆

[wellsprop]

@Wez no need to apologise, I do rather like all the avionic chat as it's really not my area of expertise.

 

I chose the design and aerodynamics pathway of my degree, so I didn't go into avionics and systems in depth. I'm having to learn an awful lot about avionics and systems now I'm engineer/aircrew in military aircraft!

 

I understand how to use avionics to do flying stuff however, my view of avionics and systems is as follows:

 

1. Aircrew input, 

2. Black magic, 

3. Electromagnetic wave output, 

4. More black magic, 

5. Lights on screens for aircrew.

 

On the aircraft I work on, though a doppler sensor is still present, it's not the primary source for information. GPS and INS have got so much better now that they are replacing older sensors.

[Wez]

58 minutes ago, wellsprop said:

@Wez no need to apologise, I do rather like all the avionic chat as it's really not my area of expertise.

 

I chose the design and aerodynamics pathway of my degree, so I didn't go into avionics and systems in depth. I'm having to learn an awful lot about avionics and systems now I'm engineer/aircrew in military aircraft!

 

I understand how to use avionics to do flying stuff however, my view of avionics and systems is as follows:

 

1. Aircrew input, 

2. Black magic, 

3. Electromagnetic wave output, 

4. More black magic, 

5. Lights on screens for aircrew.

 

On the aircraft I work on, though a doppler sensor is still present, it's not the primary source for information. GPS and INS have got so much better now that they are replacing older sensors.

This has always been the problem, design/structures/aerodynamics has always been the primary focus, it was the same in my time in the air force, it was a riggers air force, the emphasis was always on airframes all of the other systems are given secondary importance but actually, all of the other systems affect how the airframe needs to react/adapt to maximise the other systems effect.

 

I worked a lot on modification work providing capability upgrades to platforms, there's an awful lot more effort required by the airframe side to adapt to these changes simply because they don't understand how or  why they are needed.  For my part, I always needed to understand the airframe side of things in order to make the airframe specialists understand why they have to adapt, not us.

 

I think it's important for the airframe side to have just as much an appreciation of other disciplines as we have always had of theirs.

 

In other words learn about engines, electrics and above all, avionics!

[wellsprop]

@Wez, I totally agree, without avionics and systems any military aircraft is totally useless.

 

The airframe's job is to transport a system (whether that system is a winch, sonar, radar, camera, missile or bomb).

 

Too many people play top trumps, when comparing aircraft, with speeds or g-limits and totally miss the system capability. 

[exdraken]

1 hour ago, wellsprop said:

 

The airframe's job is to transport a system (whether that system is a winch, sonar, radar, camera, missile or bomb).

 

Too many people play top trumps, when comparing aircraft, with speeds or g-limits and totally miss the system capability. 

I am not an aeronautical engineer, but I assume that those requirements are interdependent very much. 

 

Just thinking of requirements like range, speeds, interception time, time to altitude, stealth, payload etc... where airframe and engine would be the most critical ones, whereas your system to be carried might need some adaptions to the airframe/ power  available.

 

On the other hand, when your requirements are carrying a specific system as you state, you are right, the airframe and consequently its specification will need to adapt, often sacrificing on your "top trumps"

Just my 2cts!

 

[e8n2]

22 hours ago, Wez said:

 

@wellsprop

 

Going back to the Doppler antenna, it would be quite a common fit on British aircraft from the 1970's onwards, it was fitted on Queenies (Sea King), Puma, Tonka and Sea Harrier as you've seen.  I'm guessing the Doppler was used to address the drift issues on the old gyro/accelerometer based inertial nav systems.

Actually I believe the doppler nav systems are older than INS when it comes to aircraft.  The C-130s had what we referred to in tech school as a steam driven doppler radar.  There was a mechanical part, whose name escapes me now although the name Janus, the Greek god that had eyes in the back of his head keeps coming up in my mind, that would flop over continuously so that there would be a right and left front beam and then a right and left rear beam to make it's calculations.  Maybe it was different with helicopters, although I can definitely see where a long time hovering could cause excessive drift.  The APN-218 that was in the KC-135s was all digital and based on a system originally developed for the B-1.

Later,

Dave

[Wez]

2 hours ago, e8n2 said:

Actually I believe the doppler nav systems are older than INS when it comes to aircraft.  The C-130s had what we referred to in tech school as a steam driven doppler radar.  There was a mechanical part, whose name escapes me now although the name Janus, the Greek god that had eyes in the back of his head keeps coming up in my mind, that would flop over continuously so that there would be a right and left front beam and then a right and left rear beam to make it's calculations.  Maybe it was different with helicopters, although I can definitely see where a long time hovering could cause excessive drift.  The APN-218 that was in the KC-135s was all digital and based on a system originally developed for the B-1.

Later,

Dave

 

Dave,

 

You're spot on, Doppler Systems are older,  its just that I've never worked on anything older other than during RAF trade training, the Canberra's and IIRC, the Shackleton's had it, the latter also had a pitot-static driven drift measuring equipment.

 

I certainly recall seeing Doppler links on the wiring diagrams fori the Mk10 autopilot we were taught, the system was fitted to Vulcan, Victor, RAF Hercules, Andover and Argosy which were definitely a damn sight older than the 1970's kit I worked on.

[Adam Poultney]

Looks similar to the later Doppler radar on Vulcans introduced c.1974

[Rolls-Royce]

On 9/6/2021 at 10:17 PM, e8n2 said:

Can't really help you there as those were not part of my systems.  The only difference between a U-2R and TR-1A was the serial number.  There were a few minor variations between mainly the early build U-2Rs and the later build U-2Rs and TR-1As.  Those were all internal.  All of the surviving U-2R and TR-1A airframes have had new engines fitted and are all designated as the U-2S.  I don't know for sure which engine went in and there possibly may have been a modification done to the intakes for the increased airflow of the newer engines.  AFAIK, the TR-1Bs also got the new engine and if the past is any indicator, they would be designated (incorrectly per the regs) as the U-2ST.  As I remember it, Q Bay is right behind the cockpit.  Behind that was E Bay, and that was where the INU was located along with some other avionics.  The insides of the bays are painted chromate yellow, as is the intake trunking after about the first 6 - 12" of the intake.  I had to refer to the Aerofax Minigraph #28 to refresh my memory on which bay was where (it's been over 35 years since I last worked on them).  The minigraph also talks a bit about the cameras, but I imagine that those were mostly the cameras carried by the early A and C model deuces.

Later,

Dave

I know this is an older thread, but when I was in the 100SRW at Davis-Monthan AFB, one of the U-2s I was assigned to was 56-6953, then configured as a two-seat U-2CT. Then as now, that designation didn't follow the regulations. When I asked why (being relatively recently out of technical training), I was told that it was because no pilot would admit to flying a TU-2 (say it out loud and you'll understand). I believe it! 😄

Edited January 27, 2022 by Rolls-Royce