German WW2 T-5 Torpedo Gyro

[Dronic69]

Hi All,

One of the reasons that I love to collect fuses is mostly due with my life long fascination of "mechanisms" - whether it is out of a clock, car, camera or some other device. Here's a beaut German WW2 T-5 (or earlier) torpedo gyro that I was fortunate to come across a few years ago. It is most likely a training one as it came complete with the stand and has most of it's bits - as others I have seen in the past are not as complete.

Apart from the typical German instrument precision, I found it quite fascinating how it actually operates......I have added letters to the first pic and will describe the sequence of events when the torpedo is launched and how the gyro initializes.....

Point A:
Upon launching, compressed air enters the ball shape chamber from beneath the gyro (the 2nd pic shows the view of the internal chamber when the bolt has been removed - where you can see the head of the piston). In a similar operation to that of a 1st stage Piston SCUBA regulator {the bit that attaches to the tank}, as the air pressure increases inside the chamber, the mechanical advantage (surface area of the piston head) will slowly overcome the spring tension (View from B pic) and move forwards towards the rear of the gyro.

Point B & C:
The mechanical linkage shown at point B, connects to a movement limiter at point C, which restricts the gyro movement in the horizontal plane.
As the piston continues to move rearwards, the movement limiter moves up and backwards to a point where the gyro is freely to operate.

Point D:
The gyro wheel has "slots" evenly cut around its circumference, which help assists the initial airflow to spin the gyro up to its operating 15,000 rpm. You can observe the gyro air outlet in the "Opposite View from D" pic.

So the movement limiter is design to keep the gyro in a restrictive position until it has reached its operational spin - this startup time has been calculated as the time it takes the air in the internal chamber to pressurized the piston and via mechanical linkage, release the movement limiter.

Point E:
Once operational, the gyro controls the steering (left or right) by the movement of the nozzle which injects 6 kilos pressure into a housing which in turns moves the lower piston left or right.

Point F:
Steering piston - which is eventually linked to the torpedo's rubber.

There are also some other pre-adjustments as shown on the front above the steering piston, which I assumed to be used to pre-set the torpedo's course.

I had a rough idea how it worked when I got it (I use to service my own diving equipment) - it took another 6 mths to verify the operation when I came across some U-boat archives, specifically U-371, whose crew were captured and "quizzed" by the US Navy.

I'll post those drawings in the near future in addition to pics of the gyro's stamps and markings.

Enjoy!

Cheers
Drew

BTW - I have "spun" this sucker up - unbelieveable!!! Spins forever!

 

[ben2000]

nice

Hi Drew,

That's a great piece and a great job you've done with the photos

 

[Dronic69]

Thanks Ben,

It's one of my favorite "mechanisms" (cost me an arm and a leg when the Aussie dollar was around the 0.6 compared to the USD about ten years ago...)

As promised prior, here's the gyro's stamps /markings - I'm not familiar with any of the manufacturing stamps....

Does anyone recognize and know the meaning of the 4 x star stamps "*" in the 2nd pic? There are also 3 x squizzles as well????

Any clues as to which factory produced this?

Thanks

Cheers
Drew

 

[butterfly]

Hi Drew,

Very nice item you have there and interesting write up to.

Just a thought on the stamps, could they be for testing (signifying a propeller or fan (air)).

I would have thought that these would have been well tested, maybe the squiggle represents a water test and the * a dry run (on a test bed, with compressed air)

Really I have no idea, just throwing some ideas your way, (you have probably had similar ideas yourself)

I'm sure someone will be able to positively ID them for you.

Thanks for showing
regards Kev

 

[SG500]

Nice gyro Drew.
You say "it spins forever" - just out of curiosity - how long or did you run out of time:tinysmile_fatgrin_t?
I've got a small gyro out of a missile and when you spin that by hand it goes for about 5 minutes. I'd imagine spinning that one up to 15,000 rpm would be impressive!
Dave.

 

[Dronic69]

Hi Kev,
I like your theory on the dry /wet test runs......actually I haven't put too much thought into their meaning until now- spent far more time trying to track down info on the operational side - which reminds me to post the cross-section diagrams extracted from the U-371 crew.

Hi Dave,
I have a compressed air nozzle which I can connect to my SCUBA regulator set, which from memory pumps out around 130 psi. I directed that onto the gyro wheel and boy does it sound like a jet engine taking off when it hits the "slots"!!! The bearings are a little nosy, but after the revs are pumped up a few times, it will go on for five to ten minutes - although. I don't think I get anywhere near 15,000 RPM .....(OK "forever" was a little exaggerated!) :tinysmile_hmm_t:

From memory, my US Mk12 torpedo gyro runs even longer.......really weird sensation when you hold it in your hands and attempt to change direction!
Cheers
Drew

 

[SG500]

Hi Kev,
I like your theory on the dry /wet test runs......actually I haven't put too much thought into their meaning until now- spent far more time trying to track down info on the operational side - which reminds me to post the cross-section diagrams extracted from the U-371 crew.

Hi Dave,
I have a compressed air nozzle which I can connect to my SCUBA regulator set, which from memory pumps out around 130 psi. I directed that onto the gyro wheel and boy does it sound like a jet engine taking off when it hits the "slots"!!! The bearings are a little nosy, but after the revs are pumped up a few times, it will go on for five to ten minutes - although. I don't think I get anywhere near 15,000 RPM .....(OK "forever" was a little exaggerated!) :tinysmile_hmm_t:

From memory, my US Mk12 torpedo gyro runs even longer.......really weird sensation when you hold it in your hands and attempt to change direction!
Cheers
Drew

WOW, nice, where do I get one? :tinysmile_hmm_t:
Dave.

 

[tigbrand]

torpedos

Hi Drew,what a cracking piece of kit and worth a bob or two,its not going to lose value thats for sure! Heres a link to a word document on torpedo development thats very good indeed. http://www.geoffkirby.co.uk/ then click on article on history of torpedos. hope its of interest. Tig.:bigsmile:

 

[John D. Bartleson Jr.]

German T5 Torpedo;

Hello Drew,
I have not posted for sometime now. Your U.s. gyro looks similar to the gyro used in the Mk. 18 steam fish. On weekends I demilled numerous unserviceable ones by striking them with a 5 pound hammer. It was sickening.
Your T5 German torpedo uses either the Ke or KE1 warhead and in either case it uses the PI-4C exploder. Although your gyro is located in the afterbody I thought perhaps you would like to see the 'business end' of the T5. I hope you can read the zoomed position.
Regards,
John aka Bart

 

[Dronic69]

Hi Dave,
Both gyros were purchased on the US Fleabay about ten years ago......there was even a Whitehead torpedo gyro offered a couple of years after that.....but unfortunately it was during my "inert" period and didn't bid (went for about $1K USD).

The Mk 12 gyro didn't come with the "unique" stand - as you can gather the stand looks like a gyro itself- pick it up at an Op Shop for $5. It was a candle holder - ripped the medal base and candle spike off the top and attached the Mk 12, which fitted perfectly!

Hi Tig,
Thank you for the link to Kirby's site - a very interesting Gentleman indeed!.....and yes always hunting information on torpedos

Sir Bart,
Great to hear from you and yes your absence from this forum is very noticeable!
(Humm, too much Florida sunshine is it?)
I'm cringing now when I read that you "demilled" them...such as shame as they are truely engineering marvels!
I appreciated the info on the T5 - thank you!
Speaking of which, as promised I have attached the cross-sectional diagrams of the gyro - on reviewing it, I have made an error in my above operational description:
The air flow into the internal chamber is via the piston's internal orifice, and not by a separate feed. As the pressure builds within the chamber, the increasing pressure on the surface area of the piston head provides the mechanical advantage to overcome the spring tension and moves forwards etc.
Also the gyro spins up to 20,000 rpm as there is an additional feed of 6 kilos pressure (branch off which feeds the Nozzle).

Now the T5 was an Acoustic Torpedo and as you can see from the final pic, had an acoustic control gear which "overrides" (cutouts) the gyro! This gear would be physically located over point E. I'm unable to see any evidence of this on my one and prior research from memory led me to believe this may be an earlier model (pre-war?) non-acoustic perhaps T-3?

BUT I'm not sure! I'm open to any thoughts on this???

Does anyone have a pic of the Acoustic Control Gear?

Thanks
Cheers
Drew

BTW - My apologies for the quality of the drawings. Anyone interested and access much clearer ones at the U-boat archives website:

http://www.uboatarchive.net/U-371INT.htm

Scroll down about half way - there's heaps of additional diagrams covering the complete torpedo.

 

[Fusse2004]

.

I had times in my collection!!!

 

[Dronic69]

The Holy Grail of fuse collectings! A torpedo fuse!

Hi Fusse,

Ah, the "holy grail" of fuse collecting - the torpedo fuse!!!

Very very nice!

Thank you for sharing.......a couple more bits and we'll have a complete one!:tinysmile_twink_t2:

Cheers
Drew

 

[Natter]

Here's a beaut German WW2 T-5 (or earlier) torpedo gyro that I was fortunate to come across a few years ago.

No, that is a standard GA VIII gyroscope for the german G7a (TI) and G7e (TII)/(TIII) torpedoes.

The GA VIII equipped torpedoes were "straighrunners" (the gyroscope had an angular-setting for it's initial course though, so it could for instance be fired straight north and then head 90 degrees to starboard if that was desirable).
There were additional variants of the GA VIII with different types of "programsteering", used in particular for attacks at large convoys to improve the probability of hit if the torpedo missed it's initial target: FAT I, II and III + LUT I and II (the difference was in the running patterns and possible settings for straight-legs, turn-radiuses etc).


The acoustic-seeeker G7es (TV) "Zaunknig" and G7es (TXI) "Zaunknig II" torpedoes used the electrically controlled GA VIIIs "Specht" gyroscope (distinguished by the box of control-electronic as you can see on my attachments).

 

[Natter]

Point A:
Upon launching, compressed air enters the ball shape chamber from beneath the gyro (the 2nd pic shows the view of the internal chamber when the bolt has been removed - where you can see the head of the piston). In a similar operation to that of a 1st stage Piston SCUBA regulator {the bit that attaches to the tank}, as the air pressure increases inside the chamber, the mechanical advantage (surface area of the piston head) will slowly overcome the spring tension (View from B pic) and move forwards towards the rear of the gyro.

Point B & C:
The mechanical linkage shown at point B, connects to a movement limiter at point C, which restricts the gyro movement in the horizontal plane.
As the piston continues to move rearwards, the movement limiter moves up and backwards to a point where the gyro is freely to operate.

Point D:
The gyro wheel has "slots" evenly cut around its circumference, which help assists the initial airflow to spin the gyro up to its operating 15,000 rpm. You can observe the gyro air outlet in the "Opposite View from D" pic.

Some correction to your description above:
When the torpedo starts moving through the tube, the starting lever in the engine-compartment are retracted by a bolt inside the tube. This opens the starter-valve in the air-regulator group in the enginecompartment, providing the full airpressure in the airtank to the expansionchamber of the gyroscope (ie the ball-shaped chamber). As the pressure here rises, the valve is pushed down to cut-off the starting-air - this takes just 1/4 second.
During this short time, the gyroscope initially spins up to 13500rpm by means of the starting-pressure (which is 100-200kg, depending on the filling of the airtank: For warshot, it was always the maximum of 200), and then increases further to max 21000rpm for the remaining time of the torpedorun.
After the piston has cut off the initial start-air and released the wheel, the continued run are provided by 8kg airpressure delivered from the GA regulator through the small pipes on the wheel-frame (providing air to the slotts of the wheel no matter what position it has: The start-air is only directed to the slotted wheel in it's locked position).

So the movement limiter is design to keep the gyro in a restrictive position until it has reached its operational spin - this startup time has been calculated as the time it takes the air in the internal chamber to pressurized the piston and via mechanical linkage, release the movement limiter.

The limiter is there also to provide protection for the delicate instrument during the launch-phase (for a surface-launch the 1600kg torpedo could "fly" almost 20m through the air before hitting the water from several metres height). Also, it's crucial for the function of the gyroscope that the wheel is kept perfectly still during the spin-up.

Point E:
Once operational, the gyro controls the steering (left or right) by the movement of the nozzle which injects 6 kilos pressure into a housing which in turns moves the lower piston left or right.
Point F:
Steering piston - which is eventually linked to the torpedo's rubber.

This is a "servomotor" - converting the low force of the GA's movement into the force required to move the rudder. Note that the airpressure from the GA regulator to the nozzle is in fact 8kg (same as the pressure maintaining the rotation of gyro-wheel).

There are also some other pre-adjustments as shown on the front above the steering piston, which I assumed to be used to pre-set the torpedo's course.

I'm not sure what you refer to, but it is in fact possible to preset the initial course for the torpedo by means of a special tool inserted into the spindle on the outside of the torpedo's hull (where there also is a disc that shows the setting on a red/green indicator).

BTW - I have "spun" this sucker up - unbelieveable!!! Spins forever!

Yep it sure does

When maintaining the torpedo and preparing it for a launch, the gyroscope had to be run in a stable condition (ie no drifting) for 8min. If the reference-point would shift (ie the torpedo drifting off course), this could be adjusted by the nut on the wheel-axle. Also, the max defelction and movement of the rudders had to be cheked by means of special tools mounted on the tailpiece.


I have compiled some drawings of the GA VIII gyro that might be of interest for you. It can be downloaded here: https://dl.dropboxusercontent.com/u/38692668/GAVIII.pdf

 

[Natter]

As promised prior, here's the gyro's stamps /markings - I'm not familiar with any of the manufacturing stamps....

Does anyone recognize and know the meaning of the 4 x star stamps "*" in the 2nd pic? There are also 3 x squizzles as well????

Any clues as to which factory produced this?

I don't remember now, but there were four factories producing the G7a (TI). I'm not sure if the gyroscope was produced in specialized factories though. The number in your first photo is the GA's serialnumber - also found on the transportcrate. The gyro was matched to a specific torpedo.

 

[Natter]

I have a compressed air nozzle which I can connect to my SCUBA regulator set, which from memory pumps out around 130 psi. I directed that onto the gyro wheel and boy does it sound like a jet engine taking off when it hits the "slots"!!! The bearings are a little nosy, but after the revs are pumped up a few times, it will go on for five to ten minutes - although. I don't think I get anywhere near 15,000 RPM .....(OK "forever" was a little exaggerated!) :tinysmile_hmm_t:

There are stories of incidents where the cut-off piston (ref my previous post) didn't function and cut off the starting air after the required 1/4 seconds. This made the wheel spin up to such tremendous speed that it come loose from it's cradle and broke out through the hull and spin around the workshop as a deadly projectile...
During gyro-runs in the workshop as part of the regular maintenanceroutines for the torpedo, a special tool were used for the starting lever so the lever wouldn't lock like it would do for a normal run (that would require a new tool and several seconds to release it again). This way, the startingvalve could be closed immediately by simply removing the tool if there was a malfunction. It was always a little exciting to start the gyro and listen for a malfunction. For safety-reason this was always done with high precaution.

I have seen the wheel run for more than an hour, so it could really go on for a long time.

 

[Natter]

Your T5 German torpedo uses either the Ke or KE1 warhead and in either case it uses the PI-4C exploder. Although your gyro is located in the afterbody

As mentioned above, Drews gyroscope is for the TI/TII/TIII torpedoes.

I thought perhaps you would like to see the 'business end' of the T5. I hope you can read the zoomed position.

It seems you have scanned the original minedisposal book at NARA..? I would love to get a complete copy of it with good scann-resolution... Please let me know if that would be possible (I'm sure I can provide something interesting in return).

Let me know if other documen tation for the TV torpedo is of interest (I have some original german documents as well as stuff from Royal Navy archives).

 

[Natter]

Does anyone have a pic of the Acoustic Control Gear?

See my previous posts.

Scroll down about half way - there's heaps of additional diagrams covering the complete torpedo.

Be aware that those reports are from interviews with germans POWs. There are several errors (possible intentional from the germans?). For instance: The Pi4a and Pi4b pistols were never introduced operationally according to the german original torpedoregulations.

 

[Dronic69]

HI Natter,

Great information - thank you very much! (and for the corrections! )

At the time, (quite a few years ago now) I spent 6 months "googling" before I came across the "interviews with the German POWs" information in attempt to verify how the gyro operates - it was all that I could find!

I have downloaded the diagrams.

Cheers
Drew

 

[Natter]

Great information - thank you very much! (and for the corrections! )

You are welcome - I'm happy to help/answer (if I'm able to) to anything regarding the G7a (TI) torpedo

At the time, (quite a few years ago now) I spent 6 months "googling" before I came across the "interviews with the German POWs" information in attempt to verify how the gyro operates - it was all that I could find!

I noticed that this was an old post, but I just stumbled upon this forum the other day (I'm on constant lookout for any source of information or a place to discuss this topic )

Note that there has been added more info on Jerry's site (www.uboatarchive.net) since you found that report, and more is probably coming in the future.