The U.S. Navy’s Maritime Sealift Command sails a number of odd-looking ships, but just one has the unusual background of having been built in the former Soviet Union. The USNS Lance Cpl. Roy M. Wheat, a cargo ship designed to carry supplies for the Marine Corps, was built in the former soviet republic of Ukraine and bought on the open market by the U.S. Navy. Nearly as large as an aircraft carrier, Wheat and her sister ships sit packed with Marine Corps equipment in the Mediterranean, waiting for the day they are needed.
1 Like
Love the bit where the ship is unmanned but it does have civilians onboard.
Civilians are not human. Everyone knows that.
3 Likes
The Wheat has direct reversing gas turbines right, funky stuff
1 Like
For some reason I found this hard to believe but Mr. Google says they are out there.
https://patents.google.com/patent/US2421445A/en
While a turbine for such applications should operate at high efliciency during forward propulsion, the matter of efliciency and of maximum delivery of power is generally a minor consideration during astern operation provided sufficient power may be-generated to secure a relatively slow speed. Through the use of turbine wheels of the type described in the patents to Blrmann Nos. 1,926,225; 1,959,703; 2,283,176, effective reversal may be accomplished merely by reversingthe flow of driving gases from nozzles with respect to their direction about the axis of rotation of the turbine rotors.
The gas producer (what most people would consider the engine itself) is not reversible. The power turbine contains a set of reversible blades and ducting that allow the output shaft to reverse.
This technique allows reversing without the need for reduction gearing or a controllable pitch propeller.
Bottom line, the “engine” ends at the outlet from the final stage of the turbine, just like an LM2500.
1 Like
Similar to a CPP?
No, a separate set of blades on the power turbine. There are variable guide vanes on the power turbine inlet that bypass the ahead blades and redirect gas flow to a set of reverse blades.
That makes sense, so presumably the reverse blades are spinning “backwards” when going ahead?
Yes but since there is practically no gas flow through them they don’t produce an unacceptable amount of drag. Think of them the way the reverse turbine works on a steam plant, they turn the wrong way until needed.
1 Like
It is an interesting design approach. It doesn’t make for the most efficient extraction of energy from the gas producer but since it eliminates a reduction gear, less efficient prop hubs, and the complexity of a hydraulic pitch control system the economics may well be advantageous.
Are all marine propulsion turbines of free shaft design?
I can’t think of any offhand except maybe a couple of generator drive units based on the Allison T-501/T56 single shaft engines.
1 Like
The difficulty here is comments that are not highlighted as humorous will br not understood by some that ‘unmanned’ refers to UMS class notation and not ‘autonomous vessels’.
The Military Sealift Command has more types of than the rest of the Navy. I worked on the USNS Wheat conversion. It was a Ukrainian built ship for MORFLOT. I was chartered and converted to Navy rqmts. It was converted to a CON/RO to lift Marine tactical vehicles, containers and Naval Support Element gear.
The USNS Wheat has NO sisters in the fleet, it was one of four RO-80 class built.
While originally in the MSC Prepositioning ship force, it has been transferred to the Strategic Sealift Program. I believe it is in ROD now.
I went past it just a few days ago. Its holding up Pier N at Lambert’s Point Docks.