Lockheed YO-3A Quiet Star: The Original Stealth Aircraft of the Vietnam War

by August 13, 2014 08/13/14
Lockheed YO-3A Quiet Star

From French balloons used in 1794 to monitor troop movements to the translucent winged Rumpler Taube of World War I, surveillance and aerial reconnaissance aircraft have come a long way since their initial inception. Using aircraft to observe the battlefield quickly became an incredible asset to mission planning. Simply affixing cameras to ordinary aircraft proved useful, but the need for more discreet “watching” became apparent.

The Lockheed YO-3A Quiet Star was the United States’ answer to the need for an observation aircraft during the Vietnam War. While not necessarily designed to avoid radar detection, the YO-3A was developed to hide from human detection. Yes, the Lockheed U-2 and SR-71 were fast, stealthy and just plain sexy high-altitude reconnaissance aircraft, but they simply couldn’t operate like the Quiet Star. While those two Cold War creations hid from radar by flying high above and relying on physical stealth properties, the YO-3A could stay low and cruise directly above the enemy without fear of being discovered. Operating covertly on numerous missions, this was the original stealth aircraft.

Photo © Larry Vetterman

Photo © Larry Vetterman

Acoustically undetectable from the ground when flying around 1,200 feet, the YO-3A silently observed troop movement in Vietnam. Some pilots have also said that they went unnoticed by the enemy just 200 feet below them.

Nearly silent, this reconnaissance aircraft would patrol in the dead of night with absolutely no lights on. Using a downward facing night vision aerial periscope, the two man crew would fly above the enemy, taking notes of what they saw as well as call in support and direct artillery fire if needed.

Lockheed YO-3A Mission Equipment

What made this aircraft so quiet was mainly its slow turning propeller and heavily modified exhaust. The muffler ran the length of the aircraft which enabled sound to be incredibly dampened. Everything about this aircraft was designed to reduce noise. Instead of using gears, a belt system powered the propeller and the low rpm engine kept things quiet while eliminating vortices. The Quiet Star also had radar absorbing paint and it was said that once the pilot switched off their transponder, the tower couldn’t pick them up on radar.

The YO-3A’s were successful in their missions and thanks to being nearly completely silent, never took a round or were shot down during their time in Vietnam. In fact, they would have been used more if they weren’t deployed so late in America’s involvement of the war.

After the Vietnam War, YO-3A’s saw use as a way to catch poachers through the Louisiana Department of Fish and Game, as well as a role in the FBI’s search for Patty Hearst. NASA has also used a YO-3A for acoustical testing of helicopters and tilt rotor aircraft, in addition to measuring the sonic boom of the SR-71. Being nearly silent, it makes the perfect testbed for researching the sounds made from other aircraft. In fact, the YO-3A is actually quieter than most wind tunnels too.

Lockheed YO-3A Quiet Star
NASA Ames Research Center

Photo © NASA Ames Research Center

If you’re looking for more information on the Quiet Star, I highly recommend you visit YO-3A.com. They’re a group of individuals that all share the same interest in preserving the history of the Quiet Star. Kurt Olney, former YO-3A Crew Chief, historian and webmaster of the site, is also working on a restoration of the aircraft. It would be incredible to see one of these in action at an air show someday.

Further Reading

Update: Commenter Dale Ross Stith brought to our attention that another aircraft, the QT-2PC, flew missions prior to the YO-3A. This information brought makes the current title of this article a bit misleading. Mr. Stith has personally worked on all of the Lockheed Quiet Aircraft Programs and informed us of this: “Accumulating approximately 600 hours of night combat, the QT-2PCs were the 1st aircraft to survive a  hostile environment (Vietnam) by means of ‘low observables’.” Thank you to Mr. Stith for sharing.


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Dale Ross Stith
Dale Ross Stith

Mr. Petrucci, 

Thanks for your prompt response.

Please paste prizecrew.org and also quietaircraft.org in your browser is just search for the websites. You will see the basics of the aircraft programs on the websites identified.

I personally worked on all of the Lockheed Quiet Aircraft Programs, including the YO-3As. So, my goal isn't to diminish their value. My goal is correct mis-truths in published articles based on incorrect inputs.

Our Tri-Service aircrews flew the experimental QT-2PCs (also known as X-26Bs), mostly two four hour missions on each of the two aircraft each night through the 1st Qtr of 1968, including the TET Offensive - All to prove an unproven concept: Covert Airborne Reconnaissance, The Prize Operational Evaluation justified Full Scale Development of the YO-3A (initially named QT-3).

Accumulating approximately 600 hours of night combat, the QT-2PCs were the 1st aircraft to survive a  hostile environment (Vietnam) by means of "low observables".


Dale Ross Stith


Dale Ross Stith
Dale Ross Stith

Mr. Petrucci 

"Lockheed YO-3A Quiet Star: The Original Stealth Aircraft of the Vietnam War" is incorrect : It was preceded by two years by the QT2PC. See www.quietaircraft.org\QT-2....X-26B.

Dale Ross Stith 11/27/2014

MikePetrucci
MikePetrucci moderator

@Dale Ross Stith Thank you Mr. Stith for sharing your input. I'll certainly be visiting those websites you listed. I also appreciate you taking the time to leave these comments and will be looking into making some edits soon.

MikePetrucci
MikePetrucci moderator

@Dale Ross Stith Thanks for the link Mr. Stith but it didn’t work for me. It’s not clickable for some reason.


From what I read during research, the entire project originally came from gliders (Schweizer 1-26 and 2-32) with the idea that adding a silenced engine and slow operating prop would add to the already incredible lift of a glider for quiet flight. 


The way I saw it was that the QT-2 was a stepping stone that led to the YO-3A as the QT-2 only saw operational trials in Vietnam while the YO-3A took part in multiple missions throughout its life.


The YO-3A also had something its predecessors didn’t which was a target designator for guided weapons instead of just the Starlight Scope for visual observation. 


With that said however, that was how I came the conclusion I did to make that claim but it looks like you certainly have done more research and know the programs more intimately. I didn’t come across anything that said the QT-2 had actual missions in Vietnam as what I found only mentioned final testing.


Thanks for bringing this up though because it’s an incredibly interesting idea to me. I got to see NASA’s YO-3A when visiting the Dryden Flight Research Center a year or two ago.


Do you have any pictures you could share or more information on the QT-2? Again, thanks for the comment and I look forward to learning more about these aircraft.

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