https://www.rallypoint.com/answers/saw-a-3-engine-variant-of-the-sr-71-in-seattle-museum-does-anyone-know-how-many-of-these-were-built-and-why-they-needed-the-extra-engine <div class="images-v2-count-1"><div class="content-picture image-v2-number-1" id="image-167772"> <div class="social_icons social-buttons-on-image"> <a href='https://www.facebook.com/sharer/sharer.php?u=https%3A%2F%2Fwww.rallypoint.com%2Fanswers%2Fsaw-a-3-engine-variant-of-the-sr-71-in-seattle-museum-does-anyone-know-how-many-of-these-were-built-and-why-they-needed-the-extra-engine%3Futm_source%3DFacebook%26utm_medium%3Dorganic%26utm_campaign%3DShare%20to%20facebook' target="_blank" class='social-share-button facebook-share-button'><i class="fa fa-facebook-f"></i></a> <a href="https://twitter.com/intent/tweet?text=Saw+a+3-engine+variant+of+the+SR-71+in+Seattle+museum.+Does+anyone+know+how+many+of+these+were+built+and+why+they+needed+the+extra+engine%3F&amp;url=https%3A%2F%2Fwww.rallypoint.com%2Fanswers%2Fsaw-a-3-engine-variant-of-the-sr-71-in-seattle-museum-does-anyone-know-how-many-of-these-were-built-and-why-they-needed-the-extra-engine&amp;via=RallyPoint" target="_blank" class="social-share-button twitter-custom-share-button"><i class="fa fa-twitter"></i></a> <a href="mailto:?subject=Check this out on RallyPoint!&body=Hi, I thought you would find this interesting:%0D%0ASaw a 3-engine variant of the SR-71 in Seattle museum. Does anyone know how many of these were built and why they needed the extra engine?%0D%0A %0D%0AHere is the link: https://www.rallypoint.com/answers/saw-a-3-engine-variant-of-the-sr-71-in-seattle-museum-does-anyone-know-how-many-of-these-were-built-and-why-they-needed-the-extra-engine" target="_blank" class="social-share-button email-share-button"><i class="fa fa-envelope"></i></a> </div> <a class="fancybox" rel="782d1fc09aa41a7a826d017c4b6aece3" href="https://d1ndsj6b8hkqu9.cloudfront.net/pictures/images/000/167/772/for_gallery_v2/dd2ad76a.jpg"><img src="https://d1ndsj6b8hkqu9.cloudfront.net/pictures/images/000/167/772/large_v3/dd2ad76a.jpg" alt="Dd2ad76a" /></a></div></div> Sat, 05 Aug 2017 14:57:21 -0400 https://www.rallypoint.com/answers/saw-a-3-engine-variant-of-the-sr-71-in-seattle-museum-does-anyone-know-how-many-of-these-were-built-and-why-they-needed-the-extra-engine <div class="images-v2-count-1"><div class="content-picture image-v2-number-1" id="image-167772"> <div class="social_icons social-buttons-on-image"> <a href='https://www.facebook.com/sharer/sharer.php?u=https%3A%2F%2Fwww.rallypoint.com%2Fanswers%2Fsaw-a-3-engine-variant-of-the-sr-71-in-seattle-museum-does-anyone-know-how-many-of-these-were-built-and-why-they-needed-the-extra-engine%3Futm_source%3DFacebook%26utm_medium%3Dorganic%26utm_campaign%3DShare%20to%20facebook' target="_blank" class='social-share-button facebook-share-button'><i class="fa fa-facebook-f"></i></a> <a href="https://twitter.com/intent/tweet?text=Saw+a+3-engine+variant+of+the+SR-71+in+Seattle+museum.+Does+anyone+know+how+many+of+these+were+built+and+why+they+needed+the+extra+engine%3F&amp;url=https%3A%2F%2Fwww.rallypoint.com%2Fanswers%2Fsaw-a-3-engine-variant-of-the-sr-71-in-seattle-museum-does-anyone-know-how-many-of-these-were-built-and-why-they-needed-the-extra-engine&amp;via=RallyPoint" target="_blank" class="social-share-button twitter-custom-share-button"><i class="fa fa-twitter"></i></a> <a href="mailto:?subject=Check this out on RallyPoint!&body=Hi, I thought you would find this interesting:%0D%0ASaw a 3-engine variant of the SR-71 in Seattle museum. Does anyone know how many of these were built and why they needed the extra engine?%0D%0A %0D%0AHere is the link: https://www.rallypoint.com/answers/saw-a-3-engine-variant-of-the-sr-71-in-seattle-museum-does-anyone-know-how-many-of-these-were-built-and-why-they-needed-the-extra-engine" target="_blank" class="social-share-button email-share-button"><i class="fa fa-envelope"></i></a> </div> <a class="fancybox" rel="7cc7e4d2f5fac4c65f4c1dcd94819f09" href="https://d1ndsj6b8hkqu9.cloudfront.net/pictures/images/000/167/772/for_gallery_v2/dd2ad76a.jpg"><img src="https://d1ndsj6b8hkqu9.cloudfront.net/pictures/images/000/167/772/large_v3/dd2ad76a.jpg" alt="Dd2ad76a" /></a></div></div> Capt Seid Waddell Sat, 05 Aug 2017 14:57:21 -0400 2017-08-05T14:57:21-04:00 https://www.rallypoint.com/answers/saw-a-3-engine-variant-of-the-sr-71-in-seattle-museum-does-anyone-know-how-many-of-these-were-built-and-why-they-needed-the-extra-engine?n=2804006&urlhash=2804006 <div class="images-v2-count-0"></div>If I remember right, that isn&#39;t a 3rd engine, it is a reconnaissance drone attached to the aircraft....and I just doubled checked, it is a drone...called the D-21 and the SR-71 was used as its infil platform for a brief period of time. SFC Private RallyPoint Member Sat, 05 Aug 2017 15:11:17 -0400 2017-08-05T15:11:17-04:00 https://www.rallypoint.com/answers/saw-a-3-engine-variant-of-the-sr-71-in-seattle-museum-does-anyone-know-how-many-of-these-were-built-and-why-they-needed-the-extra-engine?n=2804221&urlhash=2804221 <div class="images-v2-count-0"></div>Interesting, there&#39;s an SR-71 at the Pima Air &amp; Space Museum that I&#39;ve seen but I believe it only had two engines. SPC Private RallyPoint Member Sat, 05 Aug 2017 16:49:31 -0400 2017-08-05T16:49:31-04:00 2017-08-05T14:57:21-04:00