10/15/2026
Plane Facts – Engines
By Glen Broman
And now for something completely different, not just Things Under Wings, but Things Over Wings.
Engines come in different flavors, some are piston powered, some are turboprops and some are jets. They are all a critical part of the four elements of flight; Lift, Drag, Thrust and Gravity. As you can imagine, engines are a handy piece of kit to combine with lift to overcome drag and gravity.
Our specific subject for this edition of Plane Facts is the Allison T-56 Turboprop engine. The T-56 engine powers both our C-130’s and our P-3. The engines are mounted under the wings on the C-130’s and over the wings on the P-3. The usual comment is that the engine on the P-3 is upside down. In reality, not so much.
Actually, both engines are mounted “right side up”, but the reduction gearboxes are mounted differently to match each aircraft’s wing configuration. The illusion of “upside down” on the P-3 relates to the difference in how the engine nacelle and air intakes are shaped. So why is that?
The C-130 has a high wing and the P-3 has a low wing. The C-130 places the propeller shaft in a high position. The P-3 gearbox places the propeller drive shaft in a low position to align with the low mounted wing. Placing the gearboxes at a 180 degree difference, along with the exhaust placement and oil cooler intake locations, gives the illusion of an upside down orientation on the P-3.
Who knew engines could be so much fun?
We encourage the public to visit the Museum during these last weeks of October as our season will end at 5pm on Saturday, October 31st. WE WILL BE OPEN FOR VISITORS ON OCTOBER, 16, 17, 18, 23, 24, 25, 30, 31, FROM 11am - 5pm. So please don't miss out!
Museum admission and Pre-Arranged Base Security Access are necessary. Please go to our website (www.selfridgeairmuseum.org) for information and our help in gaining Pre-Arranged Base Security Access.
On our home page you should click on the yellow button that says 'Visitor Information and Access'. Then click on the yellow button that says 'Pre-Arranged Access'. Then fill out the form, then click on 'Submit'. This process is easy but usually takes a week to 10 days to get approval. So, we hope that you get started soon!