Allison T61
| {{Infobox aircraft begin
|name= T61 / 550-B1 |image= |caption= }}{{Infobox Aircraft Engine |type= Turboprop |national origin = United States |manufacturer= Allison Engine Company |first run= |major applications= Lockheed GL-207 Super Hercules |number built = 4 |status = Canceled |program cost = |unit cost = |developed from = |developed into = |variants with their own articles = }} |
The Allison T61 (known internally as the Allison 550-B1) was a {{convert|6,500|shp|kW|abbr=off|adj=mid}} turboprop engine that was to power the 1959 version of the proposed Lockheed Super Hercules military and civil freight aircraft. The U.S. Air Force (USAF) had helped Allison fund the development of the T61 for four years. Lockheed had received orders from Pan American World Airways and Slick Airways for a total of 18 aircraft, but both orders were contingent on the military ordering the aircraft by September 30, 1959, around the date that the USAF's engine development contract expired. The development contract was extended temporarily to November 30, 1959, but the T61 development effort was canceled by January 1960, after USD$37.5 million had been put into the engine's development. Four T61 engines had run on the test stand at the time of cancellation.
The Allison T61 produced {{cvt|6,500|shp|kW|adj=pre|equivalent}} at takeoff, of which {{cvt|6,102|shp}} came from the propeller, with {{convert|995|lb}} of residual jet thrust. It had a similar appearance to the Allison T56 but with a split compressor section instead of a single stage. The T61 improved on the power-to-weight ratio of the T56 by 30%. The Air Force had also given Allison's Aeroproducts Operations division a USD $4 million contract to develop a {{cvt|16+1/2|ft|m|adj=mid|diameter}}, four-bladed propeller to use on the T61-powered Super Hercules.
Specifications
{{jetspecs
|ref=Aviation Week, October 5, 1959, page 30 and the 1960 Aerospace Year Book, page 91{{R|"AIA1960"|p=[https://www.aia-aerospace.org/wp-content/uploads/2016/06/THE-1960-AEROSPACE-YEAR-BOOK.pdf#page=92 91]}} and 375{{R|"AIA1960"|p=[https://www.aia-aerospace.org/wp-content/uploads/2016/06/THE-1960-AEROSPACE-YEAR-BOOK.pdf#page=376 375]}}
|type=Twin-spool turboprop
|length={{cvt|142|in}}
|diameter={{cvt|33|in}}
|weight={{cvt|2,240|lb}}
|compressor=9-stage high pressure, 6-stage low pressure
|combustion=
|turbine=2-stage high pressure, 3-stage low pressure
|fueltype=
|oilsystem=
|power=Takeoff: {{cvt|6,500|shp|kW|adj=pre|equivalent}} @10,400 rpm; 90% cruise: {{cvt|5,070|shp|kW|adj=pre|equivalent}}
|thrust=
|compression=
|bypass=
|aircon=
|turbinetemp={{cvt|1,855|F|C R K}}
|fuelcon=
|specfuelcon=Takeoff: {{cvt|0.500|lb/hph|kg/hph kg/kWh}}; Cruise ({{cvt|35,000|ft|m|adj=mid|altitude}}, {{cvt|320|kn|mi/h km/h}}): {{cvt|0.51|lb/hph|kg/hph kg/kWh}}
|power/weight=
|thrust/weight=
}}
See also
References
{{Reflist|refs=
{{cite magazine |issn=0005-2175 |magazine=Aviation Week |title=Air Force cancels T61 development program |url=https://archive.org/details/Aviation_Week_1960-01-11/page/n15 |publication-date=January 11, 1960 |location=Washington, D.C., U.S.A. |page=30 |volume=72 |number=2}}
{{cite magazine |issn=0005-2175 |magazine=Aviation Week |title=Contract end clouds T61 future |url=https://archive.org/details/Aviation_Week_1959-10-05/page/n16 |publication-date=October 5, 1959 |location=Washington, D.C., U.S.A. |page=33 |volume=71 |number=14}}
{{cite magazine |issn=0005-2175 |magazine=Aviation Week |title=Cherington foresees airline fare cuts |url=https://archive.org/details/Aviation_Week_1959-04-20/page/n20 |publication-date=April 20, 1959 |pages=40–41 |location=Las Vegas, Nevada, U.S.A. |volume=70 |number=16}}
}}
Bibliography
{{refbegin}}
- {{cite magazine |issn=0005-2175 |magazine=Aviation Week |title=Airline observer |url=https://archive.org/details/Aviation_Week_1959-10-19/page/n24 |publication-date=October 19, 1959 |page=49 |volume=71 |number=16}}
- {{cite magazine |issn=0005-2175 |magazine=Aviation Week |title=C-130 Hercules lengthened to increase long-range missions |url=https://archive.org/details/Aviation_Week_1959-06-15/page/n31 |publication-date=June 15, 1959 |page=62 |given=J.S. |surname=Butz, Jr. |volume=70 |number=24}}
- {{cite magazine |issn=0005-2175 |magazine=Aviation Week |title=Industry observer |url=https://archive.org/details/Aviation_Week_1958-11-17/page/n11 |publication-date=November 17, 1958 |page=23 |volume=69 |number=20}}
{{refend}}
External links
- {{cite magazine |issn=0730-6784 |author=Lockheed Corporation |author-link=Lockheed Corporation |magazine=Air Force Magazine |title=New Lockheed Super Hercules: Big brother of U.S. Tactical Airlift champ |url=https://hdl.handle.net/2027/osu.32435061974283?urlappend=%3Bseq=674 |hdl=2027/osu.32435061974283 |publication-date=November 1959 |pages=12–13 |volume=42 |number=11}}
{{Allison aeroengines}}
{{USAF gas turbine engines}}