8 Cylinder Torpedo Engine - Restoration

[Tony B]

I just want to hear it running! 😀

[MatchFuzee]

Explosion Museum of Naval Firepower is surely worth contacting. 

https://www.nmrn.org.uk/our-museums/explosion-museum-naval-firepower

[64EK26]

I think that this will be of interest

21 inch 8-cylinder engine tests

Admiralty: Royal Navy Torpedo Factory and Torpedo Experimental Establishment: Reports and Technical Notes. RNTF SCIENTIFIC AND TECHNICAL REPORT. 21 inch 8-cylinder engine tests.

 

Held by:	The National Archives - Admiralty, Navy, Royal Marines, and Coastguard
Date:	1940
Reference:	ADM 290/450
Subjects:	Armed Forces (General Administration) | Manufacturing | Navy | Research | Weapons

link is http://discovery.nationalarchives.gov.uk/details/r/C528904

I will also have a look in the Collingwood collection, but I think all the torpedo archives we have are much much earlier

Cheers

Richard

[SimonBrown]

1 hour ago, 64EK26 said:

Admiralty: Royal Navy Torpedo Factory and Torpedo Experimental Establishment: Reports and Technical Notes. RNTF SCIENTIFIC AND TECHNICAL REPORT. 21 inch 8-cylinder engine tests.

Good spot Richard, it was already on my reading list at the NA for next year - but the link much appreciated as I could have equally missed it.

The friend of mine still has a few much older mystery torpedo parts - if you turn up anything in the Collingwood collection relating to Whitehead torpedoes then do please let us know.

 

20 hours ago, MatchFuzee said:

Explosion Museum of Naval Firepower is surely worth contacting. 

Another one I was going to follow up on, but it looks like they are suspending access to archive material while they move their collection. Thankfully there will be the chance for a face-to-face "Ask and Archivist" day so will keep an eye on those.

 

On 12/25/2018 at 7:11 AM, Tony B said:

I just want to hear it running! 😀

Me too! To think such a sound has not been heard for a very long time...8-cylinder 2-stroke...open pipe...

[SimonBrown]

Well the first step was to scan it into a 3D model. Should be a great reference and reminder when it comes to reassembly.

The poppet valve covers have an 8-splined socket machined into them. Looks like someone went to a lot of trouble to make that. So far, that looks like the only special tool needed, but I have a sneaking feeling this will change as it comes apart.

The poppet valve covers are also numbered 1 to 8. So far, no other numbers found.

Link to the model here - its quite complex and will take a while to load.

[robin craig]

Simon, is the technology to scan and make that kind of image within reach for most people, cost wise?

I am intrigued as to the applications possible, is this your trade or are you just younger and more skilled than me?

 

 

[SimonBrown]

8 hours ago, robin craig said:

Simon, is the technology to scan and make that kind of image within reach for most people, cost wise?

I am intrigued as to the applications possible, is this your trade or are you just younger and more skilled than me?

 

 

Like most things related to cost, its all a question of what you really need as a result. The cost is typically in the detail needed.

First up, the camera. I have used my iPhone to scan, and have my full frame DSLR. The iPhone is almost a perfect camera, but only by the measure of its in your pocket when you need it. When it comes to pixel density - the thing that drives accuracy and level of detail in a 3D model - the DSLR wins hands down and is used every time I'm underwater (most of my work is underwater stuff) or when I want a detailed record like the motor here.

The gap between the cost of a DSLR and an iPhone seems to be closing, but even now the DSLR costs more. It really depends on detail needed. More detail = more cost.

Then the software to process the models comes in two forms; Basic and Pro. The basic one will render a lifelike 3D object but it will lack accurate scale. If you wanted to scan a section of the Atlantic Wall then the Pro version will not only allow you to scale it for accuracy, but to also embed geographic data to then reference the model in the real world. The Pro version can also create what is called an ortho photo and a Digital Elevation Model. The ortho photo is like a site plan, with a scale of 1mm per pixel (typically) and the DEM shows height in colours - this link will show more P-47D Crash Site. 

There is approx 10x cost difference between the two versions of software and for scaling alone I have the Pro. If you want to print or model a replacement part from the 3D scan then scaling will be needed.

Then there is the hardware to process the models on. More detail = more time, or a faster computer. The processing of 3D data really benefits from a graphics card, which are normally as much as a decent laptop in their own right. Lots of RAM is needed too, plus the fastest processor you can buy will typically help. Or you can use older hardware and wait a long time, or work with much reduced detail. One job I did for the University of Nottingham was to scan the wreck of the SS Thistlegorm in the Red Sea. 24,000 images were needed to scan the wreck and its military cargo of trucks and ammunition, and even with some very costly cloud processing it still took 65 days of computer time to finish the job.

The hardware I use to process 3D data is not cheap: Around £4k for a capable PC that does 99% of what I need in a timeframe I can live with. I rent time in the cloud when I really need more capacity for larger models.

By now you may well have guessed its a trade/job for me. Work is not regular, but there are very few people doing this kind of work underwater and I have delivered two jobs for National Geographic TV Channel - one on Port Royal in Jamaica and one in Greece looking at the seabed and wondering if it was man-made or not. I have access to a drone too, but rarely use this for 3D work as there are others already doing it. My real love and passion is history thats underwater, so being able to scan and bring back models of what I see and share it is very rewarding. Last October I dived in Scapa Flow and paid a sonar target a visit...thus becoming the first in 100 years to see a battleship anchor from the German High Seas Fleet. With photogrammetry (the technique) means I can let everyone else know what it looks like - scroll down on this page if interested.

So is this 3D stuff in in reach of everyone? Short answer is 'yes' if you have a PC, camera and the software (Agisoft is the company and they have a 30 day trial download). Its quite easy to get a basic model done in a short time, but the detail and accuracy will always take a little longer to master.

I do think there is an application to recreate or copy the hard-to-find/impossible-to-replace things that all sorts of vehicles need. 3D scanning is just one step on a path than leads via 3D printing to lost wax casting in low volumes, or machined replacements.

Edited December 28, 2018 by SimonBrown

[David Herbert]

What an excellent summary Simon !

David

[robin craig]

Thanks Simon, I forgot about the Thistlegorm project you shared before, short memory.

 

I find with technology today we are in a great place for restorations involving remaking parts that are no longer available. Your 3D stuff is part of that in my books.

 

Thanks

[MatchFuzee]

The links are well worth looking at. The questions about the P47 crash site must be really frustrating.

In answer to this:-

"The model, DEM and ortho photo can now be examined by a non-diving aircraft engineer who maintains a flying example (if you know one, do get in touch)".

I don't know any aircraft engineers who maintains a flying example but Fighter Aviation Engineering LTD. operate one:-

https://www.flyinglegends.com/aircraft/republic-p-47d-thunderbolt-g-thun.html

 

[SimonBrown]

38 minutes ago, MatchFuzee said:

The questions about the P47 crash site must be really frustrating.

It kind of is, and isn't at the same time. We would love to ID the aircraft but as its taken somewhere between 15 & 20 years to get to where we are now, patience really is a virtue. The sea never gives up its secrets lightly.

We thought we had a serial number match recently and requested the record card from the USAF Historic Branch, but when it arrived it was apparent that the ID was for an aircraft that was written off thanks to non-battle damage and was salvaged. Clearly ours wasn't salvaged, plus the recorded date of loss didn't match.

Thanks for the link. It might be worth dropping them an email and ask if they could take a look. Apart from the data plate only the main wing spars were stamped with the serial number, but anecdotally we hear the control linkages were informally marked once they had been set/adjusted on the build line. It would be handy to confirm that.

Edited December 29, 2018 by SimonBrown

[MatchFuzee]

1 hour ago, SimonBrown said:

Apart from the data plate only the main wing spars were stamped with the serial number

I, assume that you don't know the engine number and even if you did, would it be traceable back to a specific plane? 

[SimonBrown]

8 minutes ago, MatchFuzee said:

I, assume that you don't know the engine number and even if you did, would it be traceable back to a specific plane? 

No, and no - serialisation of major components and their attachment to airframes hadn't gone to the later levels of detail. Knowing the engine number won't help, only the manufacturers or USAF serial ID.

We did spend an entire dive having a hunt for the engine data plate but no joy. The radial engine casings have fizzed away in the salt water and the conclusion is said plate has gone the same way.

[MatchFuzee]

Simon, having just re-read "Bolt in the Bay – P47-D Crash Site", is it possible that the date of the crash recorded in the Portland War Diary is wrong? Logical, a record of the plane being lost should exist in America but the date, even if only one day out, would put the search for information off course.

[SimonBrown]

On 1/1/2019 at 5:54 PM, MatchFuzee said:

Simon, having just re-read "Bolt in the Bay – P47-D Crash Site", is it possible that the date of the crash recorded in the Portland War Diary is wrong? Logical, a record of the plane being lost should exist in America but the date, even if only one day out, would put the search for information off course.

Well this has not been something we previously considered. Of the two sets of records - RN and USAF - the latter has (anecdotally) been acknowledged to be occasionally lacking detail and accuracy.

We have taken the RN record at face value. I was in the National Archives again today and double-checked the entry, just to make sure (have a horrible habit of transposing numbers...) but it was the 7th of May. 

That aside, its worth looking again at the P-47D records and see if we have anything matching - worth following up so thanks for the lateral thinking. 

 

[MatchFuzee]

Another thought on the date of the crash. When the American archive was contacted how was the date written? If it was 07/05/1944, it would not mean the 7th May 1944 to the archivist but July 5th 1944.

[SimonBrown]

20 minutes ago, MatchFuzee said:

Another thought on the date of the crash. When the American archive was contacted how was the date written? If it was 07/05/1944, it would not mean the 7th May 1944 to the archivist but July 5th 1944.

American record cards are indeed month/day/year - that possibility has been taken into account.

[SimonBrown]

A trip to the National Archives on Friday was reasonably productive. The 21 inch 8-Cylinder technical report was viewed and it actually contained a couple of photographs of the test unit. Whilst similar in design it was apparent (from the cylinder head bolt pattern) the engines were not identical. There were other reports that mentioned an 8-cylinder engine and have a bit of reading to do - all interesting stuff.

But one thing jumped out of the tech report. The engine was designed to produce (and tested to) a rather impressive 800hp. I don't see any reason why my example would not be equally capable?

Edited January 7, 2019 by SimonBrown

[SimonBrown]

One step forward...one back.

The hydraulic table platform arrived today. Its going to save my back no end and with space at a premium in the garage I can move it around...all fine...got the engine on the load bed and raised it...only to find the damm thing would then not lower. No amount of fiddling with the lever resolved it. 

After a bit of head scratching I managed to get the motor off the load bed, and sure enough it lowered when the lever was pulled. A quick test, by sitting on it and trying to lower myself, repeated the problem. So its back to the supplier I fear.

Starting to plan the first steps one job will be getting the injector pipes rust-free. I am loathed to use wire wool or other abrasive methods, so has anyone suggestions on how to clean the rust off without abrading the whole pipe?

Rusty pipe and painted example:

Edited January 10, 2019 by SimonBrown

[MatchFuzee]

 

[David Herbert]

Actually the limit is that the entire supply of air for combustion comes from a very high pressure cylinder. There is no way that a supercharger is going to produce those kinds of pressures and still leave much power to drive something. This engine produces the power that it does because it is only designed to run for about a minute and does not have to suck in air from the atmosphere and then compress it itself to produce self ignition. 

Having said that I expect that it would be most impressive to run it off a 250bar full size cylinder of air. It might need a prop to give it some work to do to stop it over speeding though.

David

Sorry everyone, this is a response to the last post on page one, I thought I was looking at page two !

Edited January 10, 2019 by David Herbert
Dementia

[SimonBrown]

30 minutes ago, David Herbert said:

Having said that I expect that it would be most impressive to run it off a 250bar full size cylinder of air. It might need a prop to give it some work to do to stop it over speeding though.

Well, the good news is the garage is well stocked with dive kit, and 250bar cylinders are in abundance. 

[watercart]

So far so good, but the system essentially runs off both high pressure and massive volume throughput of the air.  The torpedo air pipes direct from the air flask are quite large compared with dive cylinders.  I will have a look at the sectioned Mk.VIII and confirm what air pipe diameter it has.  Getting ahead of ourselves a bit, but knowing the cubic inch displacement of the 8 cyl engine compared with the Mk.VIII's BBC 4 cylinder would give some idea of what increase in volume flow rate would be needed.  If a Mk.VIII engine rates at 550HP and the 8 cyl rates at 800HP, then roughly 50% more air flow for the 8 cyl?

[earlymb]

You could try electrolysis to remove rust, but it also takes off any paint.

[watercart]

I took a measurement of the internal diameter of the air line from the Mk.VII torpedo air reservoir. It is 3/4 inch, so capable of discharging a lot of air quickly.

Given that it is an historic artifact, keeping a bit of patina on the steel and brass would be standard museum practice.  Fine or medium steel wool and oil would remove the soft rust scale but leave a stable patina and paint.  If you want to go down that path (as opposed to attempting to make it look brand new), you can get products now that apply over the steel components' patina that makes them look good and protects against further rusting.  From the photos, it is not clear whether there is much brass as the earlier engines, but it would be the crank case material and some pipework if anything.