TVT - The Skylark That Couldn't
Posted: Sat Jun 19, 2021 1:52 pm
This project grew out of the frustration experienced making a series of small steam loco projects perform satisfactorily. It can be done, but the performance of very small live steamers is on a knife edge and I don't have the patience to spend more time trouble shooting/reworking a model than the time it took to build it.
Hence this project...........
Model Notes
I've known of the existence of what Bill Russell referred to as the 'little' engine for many years and it was on the list when I took up modelling timber tramways in large scale. These Skylarks are only little takkers and having determined that getting one to work well as a live steamer in 1:20.3 scale was going to be a struggle, thoughts turned to battery electric power.
The first job was to build a basic chassis and power train and do some tests. These were successful and pointed the way forward to being able to fit adequate battery power in the limited available space and getting good running and speed performance.
The photo below shows the finished chassis after all the detail like headstocks, cylinders etc. had been added to make it look like a steam loco and not a diesel with a very strange wheelbase. General construction is based on my normal live steam chassis design. Like the old Mortein adverts said, 'When you're on a good thing stick to it'.
The motor is a 6V Pololu 20mm gearmotor with a 29:1 reduction and a 1:1 final drive using 0.8mod Hostalen mitre gears. The large diesel I built last year uses the same gears with a larger Pololu motor and this chassis runs just as well as the diesel. Quiet, smooth and plenty of power.
The motor is mounted at an angle to leave space under it for a chassis stretcher and the spring on the trailing truck. It sticks up out of the cab floor by a few mm, but is hidden by the firebox when the cab interior is fitted.
Bodywork is built the same way as I build live steamers. Normally I use 0.5mm brass sheet for bodywork, but this one is 0.6mm. The model is small and the more weight I can build into it, the better it will perform. Current calculations are that it will weigh about 1.8kg.
Kerr-Stuart must have owned a rivet factory, as their locos have more rivets than you can poke a stick at. On this model the rivets on the headstocks are individual 3/64" brass rivets, but those on the brass bodywork are punched out in the usual way, using the rivet press I made to use with my small mill.
The only real difficulty building the bodywork was due to Kerr-Stuart. Why their designers thought a cheap and cheerful industrial loco needed rounded cab and tank corners escapes me. Getting all the corners in the right place for the parts to fit together neatly was not easy. It can be done by making flanging plates and various jigs, but I draw the line at spending a lot of time making jigs for a one-off model. As usual I resorted to traditional bending bars and much bad language.
The photos below show the model cosmetically complete. It also emphasises how small a Skylark was, as the engineer figure scales out at 5' 8" which isn't tall by Aust. standards and he barely fits under the roof.
That is now where the project stands. The control system is partly complete and will be manual, but due to our 4th lockdown and other reasons, it will be a while until I can get the electronics necessary to complete the model. Like the O&K completed recently it will then sit in the paintshop queue until the weather improves. The sun was out today, but it was as cold as charity outside. I'm not complaining though, at least I have a roof over my head and electrical power.
Prototype Notes
At the start of the 20th century, Kerr-Stuart built two of their little Skylark class locos and shipped them to India, which was only the start of their travels. A couple of years later they were shipped back to Kerr-Stuart, rebuilt and sold again for further service to Australian buyers.
K-S no. 742 had been named Lukee and no 743 had been named Rajah while in India. No. 742 was sold to a silver mine at Zeehan in Tas. and no. 743 to a copper mine at Pine Creek in the NT.
742 stayed in Tassie until after WW1, when it was sold to the SA Govt. and used at the pumping station at Cobdogla on the Murray River. A couple of years later it was sold again to the SR&WSC in Victoria and put to work moving coal skips from the VR mainline at Red Cliffs to another pumping station on the Murray River. There it stayed, being withdrawn in the early '50s and 'preserved' by spending many years plinthed in a local park. It was eventually rescued by local steam enthusiasts. Restored to running condition and renamed Lukee, it still runs trips for visitors to the area.
743 travelled even further in it's working life. After a few years at Pine Creek, it was sold to machinery merchants in Melbourne who then sold it to a copper mine at Whim Wells in WA, where it joined two older Skylarks. At the start of WW1 it was sold back to the same machinery merchants. After the war it was rebuilt in Qld. and sold to a gold mine on Misima Island off the coast of New Guinea. This mine folded a couple of years later and it was sold back to the machinery merchants, regauged to 3" gauge and sold to Bill Russell at Gembrook near Melbourne for his new timber tramway. It was purchased to haul sawn timber traffic out of the forest along the Black Snake Creek to the VR ng terminus at Gembrook, but it did not do well. It was too small to pull a useful load on a timber tram with sharp curves and a 1:16 gradient and it was also described as derailing at the first hint of a curve. It was left in the back of the engine shed at Gembrook and at first replaced with a couple of petrol rail tractors, until the work was taken over by an articulated loco built in Melbourne and based on the Heisler principle. The little Skylark sat in disgrace until after the war and was cut up for scrap when the timber tram closed and the site was cleared in the early 50's.
Regards,
Graeme
Hence this project...........
Model Notes
I've known of the existence of what Bill Russell referred to as the 'little' engine for many years and it was on the list when I took up modelling timber tramways in large scale. These Skylarks are only little takkers and having determined that getting one to work well as a live steamer in 1:20.3 scale was going to be a struggle, thoughts turned to battery electric power.
The first job was to build a basic chassis and power train and do some tests. These were successful and pointed the way forward to being able to fit adequate battery power in the limited available space and getting good running and speed performance.
The photo below shows the finished chassis after all the detail like headstocks, cylinders etc. had been added to make it look like a steam loco and not a diesel with a very strange wheelbase. General construction is based on my normal live steam chassis design. Like the old Mortein adverts said, 'When you're on a good thing stick to it'.
The motor is a 6V Pololu 20mm gearmotor with a 29:1 reduction and a 1:1 final drive using 0.8mod Hostalen mitre gears. The large diesel I built last year uses the same gears with a larger Pololu motor and this chassis runs just as well as the diesel. Quiet, smooth and plenty of power.
The motor is mounted at an angle to leave space under it for a chassis stretcher and the spring on the trailing truck. It sticks up out of the cab floor by a few mm, but is hidden by the firebox when the cab interior is fitted.
Bodywork is built the same way as I build live steamers. Normally I use 0.5mm brass sheet for bodywork, but this one is 0.6mm. The model is small and the more weight I can build into it, the better it will perform. Current calculations are that it will weigh about 1.8kg.
Kerr-Stuart must have owned a rivet factory, as their locos have more rivets than you can poke a stick at. On this model the rivets on the headstocks are individual 3/64" brass rivets, but those on the brass bodywork are punched out in the usual way, using the rivet press I made to use with my small mill.
The only real difficulty building the bodywork was due to Kerr-Stuart. Why their designers thought a cheap and cheerful industrial loco needed rounded cab and tank corners escapes me. Getting all the corners in the right place for the parts to fit together neatly was not easy. It can be done by making flanging plates and various jigs, but I draw the line at spending a lot of time making jigs for a one-off model. As usual I resorted to traditional bending bars and much bad language.
The photos below show the model cosmetically complete. It also emphasises how small a Skylark was, as the engineer figure scales out at 5' 8" which isn't tall by Aust. standards and he barely fits under the roof.
That is now where the project stands. The control system is partly complete and will be manual, but due to our 4th lockdown and other reasons, it will be a while until I can get the electronics necessary to complete the model. Like the O&K completed recently it will then sit in the paintshop queue until the weather improves. The sun was out today, but it was as cold as charity outside. I'm not complaining though, at least I have a roof over my head and electrical power.
Prototype Notes
At the start of the 20th century, Kerr-Stuart built two of their little Skylark class locos and shipped them to India, which was only the start of their travels. A couple of years later they were shipped back to Kerr-Stuart, rebuilt and sold again for further service to Australian buyers.
K-S no. 742 had been named Lukee and no 743 had been named Rajah while in India. No. 742 was sold to a silver mine at Zeehan in Tas. and no. 743 to a copper mine at Pine Creek in the NT.
742 stayed in Tassie until after WW1, when it was sold to the SA Govt. and used at the pumping station at Cobdogla on the Murray River. A couple of years later it was sold again to the SR&WSC in Victoria and put to work moving coal skips from the VR mainline at Red Cliffs to another pumping station on the Murray River. There it stayed, being withdrawn in the early '50s and 'preserved' by spending many years plinthed in a local park. It was eventually rescued by local steam enthusiasts. Restored to running condition and renamed Lukee, it still runs trips for visitors to the area.
743 travelled even further in it's working life. After a few years at Pine Creek, it was sold to machinery merchants in Melbourne who then sold it to a copper mine at Whim Wells in WA, where it joined two older Skylarks. At the start of WW1 it was sold back to the same machinery merchants. After the war it was rebuilt in Qld. and sold to a gold mine on Misima Island off the coast of New Guinea. This mine folded a couple of years later and it was sold back to the machinery merchants, regauged to 3" gauge and sold to Bill Russell at Gembrook near Melbourne for his new timber tramway. It was purchased to haul sawn timber traffic out of the forest along the Black Snake Creek to the VR ng terminus at Gembrook, but it did not do well. It was too small to pull a useful load on a timber tram with sharp curves and a 1:16 gradient and it was also described as derailing at the first hint of a curve. It was left in the back of the engine shed at Gembrook and at first replaced with a couple of petrol rail tractors, until the work was taken over by an articulated loco built in Melbourne and based on the Heisler principle. The little Skylark sat in disgrace until after the war and was cut up for scrap when the timber tram closed and the site was cleared in the early 50's.
Regards,
Graeme