# What Might Have Been: Apollo's Giant Helicopter **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [January 28, 2008, 2:29pm UTC](https://boards.straightdope.com/t/what-might-have-been-apollos-giant-helicopter/435306 "2008-01-28T14:29:02Z")\ **Posts on this page:** 18\ **Page:** 1
**Author:** ![Tuckerfan](https://avatars.discourse-cdn.com/v4/letter/t/eada6e/32.png) [@Tuckerfan](https://boards.straightdope.com/u/Tuckerfan)\ **Post date:** [January 28, 2008, 2:29pm UTC](https://boards.straightdope.com/t/what-might-have-been-apollos-giant-helicopter/435306/1 "2008-01-28T14:29:02Z")
[I wouldn’t want to be the pilot.](http://www.thespacereview.com/article/1045/1) > [@](#): > > But back in 1965 the company made a proposal so bold that it bordered on insane: a giant helicopter with a rotor diameter bigger than the length of a football field, capable not merely of transporting a Saturn 5 first stage, but of actually _catching it in midair_ as it fell on a parachute. Strike that—it did not border on insane, it _was_ insane. There’s pics of the model and specs of the proposed design. Even today, I don’t really think such a chopper would be feasible. ---
**Author:** ![Really\_Not\_All\_That\_Bright](https://avatars.discourse-cdn.com/v4/letter/r/e8c25b/32.png) [@Really\_Not\_All\_That\_Bright](https://boards.straightdope.com/u/Really_Not_All_That_Bright)\ **Post date:** [January 28, 2008, 2:40pm UTC](https://boards.straightdope.com/t/what-might-have-been-apollos-giant-helicopter/435306/2 "2008-01-28T14:40:39Z")
The rotor-tip lifting system thing - jet engines attached to the end of the blades to make them revolve faster - sounds pretty effing cool, though. ---
**Author:** ![Rocketeer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rocketeer/32/4437_2.png) [@Rocketeer](https://boards.straightdope.com/u/Rocketeer)\ **Post date:** [January 28, 2008, 5:46pm UTC](https://boards.straightdope.com/t/what-might-have-been-apollos-giant-helicopter/435306/3 "2008-01-28T17:46:15Z")
The Fairey Rotodyne had something like that. Colossally noisy. ---
**Author:** ![Robot\_Arm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robot_arm/32/18280_2.png) [@Robot\_Arm](https://boards.straightdope.com/u/Robot_Arm)\ **Post date:** [January 28, 2008, 6:41pm UTC](https://boards.straightdope.com/t/what-might-have-been-apollos-giant-helicopter/435306/4 "2008-01-28T18:41:54Z")
Which makes me doubt he aero-cred of that author. He mentions a tail rotor on the Hiller, but the Rotodyne (with the main rotor also powered by tip jets) had no need of a tail rotor. The seventh engine was probably for forward thrust, not anti-torque. ---
**Author:** ![brewha](https://avatars.discourse-cdn.com/v4/letter/b/91b2a8/32.png) [@brewha](https://boards.straightdope.com/u/brewha)\ **Post date:** [January 28, 2008, 6:57pm UTC](https://boards.straightdope.com/t/what-might-have-been-apollos-giant-helicopter/435306/5 "2008-01-28T18:57:42Z")
[QUOTE=Robot Arm] Which makes me doubt he aero-cred of that author. He mentions a tail rotor on the Hiller, but the Rotodyne (with the main rotor also powered by tip jets) had no need of a tail rotor. The seventh engine was probably for forward thrust, not anti-torque. [/QUOTE] It may not need a tail rotor to counter act the high torque of conventional helicopters, but it would need a tail rotor for yaw control. The Rotodyne controlled yaw with the engines mounted on the wingtips. The propellor pitch was independantly controlled with rudder pedals. ---
**Author:** ![OtakuLoki](https://avatars.discourse-cdn.com/v4/letter/o/ac8455/32.png) [@OtakuLoki](https://boards.straightdope.com/u/OtakuLoki)\ **Post date:** [January 28, 2008, 8:07pm UTC](https://boards.straightdope.com/t/what-might-have-been-apollos-giant-helicopter/435306/6 "2008-01-28T20:07:04Z")
I’m still gobsmacked by the idea of the rotors approaching the speed of sound. :eek: ---
**Author:** ![brewha](https://avatars.discourse-cdn.com/v4/letter/b/91b2a8/32.png) [@brewha](https://boards.straightdope.com/u/brewha)\ **Post date:** [January 28, 2008, 8:14pm UTC](https://boards.straightdope.com/t/what-might-have-been-apollos-giant-helicopter/435306/7 "2008-01-28T20:14:10Z")
Well, you have to think about the size of the rotor. If each blade is 450’ long, the tips would be traveling at 800 MPH at just 25 RPM. I wonder what the rotor speed would be to hover. ---
**Author:** ![Earl\_Snake-Hips\_Tucker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/earl_snake-hips_tucker/32/3269_2.png) [@Earl\_Snake-Hips\_Tucker](https://boards.straightdope.com/u/Earl_Snake-Hips_Tucker)\ **Post date:** [January 28, 2008, 8:24pm UTC](https://boards.straightdope.com/t/what-might-have-been-apollos-giant-helicopter/435306/8 "2008-01-28T20:24:38Z")
I think each rotor blade would be about half that long, since the diameter was about 400 feet. ---
**Author:** ![OtakuLoki](https://avatars.discourse-cdn.com/v4/letter/o/ac8455/32.png) [@OtakuLoki](https://boards.straightdope.com/u/OtakuLoki)\ **Post date:** [January 28, 2008, 8:34pm UTC](https://boards.straightdope.com/t/what-might-have-been-apollos-giant-helicopter/435306/9 "2008-01-28T20:34:51Z")
I understand the combination of forces that result in that… I’m just trying to imagine a helo where the rotors are approaching a sonic boom… And the material science to build the silly things. The more I think about it the more it boggles my mind. Not only would those rotors have to withstand the stresses of near supersonic speeds, but also support the weight of two jet engines, plus fuel delivery systems. ---
**Author:** ![Robot\_Arm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robot_arm/32/18280_2.png) [@Robot\_Arm](https://boards.straightdope.com/u/Robot_Arm)\ **Post date:** [January 28, 2008, 8:40pm UTC](https://boards.straightdope.com/t/what-might-have-been-apollos-giant-helicopter/435306/10 "2008-01-28T20:40:25Z")
[QUOTE=OtakuLoki] The more I think about it the more it boggles my mind. Not only would those rotors have to withstand the stresses of near supersonic speeds, but also support the weight of two jet engines, plus fuel delivery systems. [/QUOTE] In the air, the inner portion of each blade would have to support one-third of the helicopter and Saturn V first stage; so I wouldn’t be real worried about a couple of jet engines. ---
**Author:** ![brewha](https://avatars.discourse-cdn.com/v4/letter/b/91b2a8/32.png) [@brewha](https://boards.straightdope.com/u/brewha)\ **Post date:** [January 28, 2008, 8:42pm UTC](https://boards.straightdope.com/t/what-might-have-been-apollos-giant-helicopter/435306/11 "2008-01-28T20:42:46Z")
[QUOTE=Earl Snake-Hips Tucker] I think each rotor blade would be about half that long, since the diameter was about 400 feet. [/QUOTE] From the OP > [@](#): > > a giant helicopter with a rotor diameter bigger than the length of a football field The diameter was greater than 300yds -\> 900’ ---
**Author:** ![OtakuLoki](https://avatars.discourse-cdn.com/v4/letter/o/ac8455/32.png) [@OtakuLoki](https://boards.straightdope.com/u/OtakuLoki)\ **Post date:** [January 28, 2008, 8:45pm UTC](https://boards.straightdope.com/t/what-might-have-been-apollos-giant-helicopter/435306/12 "2008-01-28T20:45:41Z")
[QUOTE=Robot Arm] In the air, the inner portion of each blade would have to support one-third of the helicopter and Saturn V first stage; so I wouldn’t be real worried about a couple of jet engines. [/QUOTE] Shh… don’t remind me of that. 😉 ---
**Author:** ![Musicat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/musicat/32/20189_2.png) [@Musicat](https://boards.straightdope.com/u/Musicat)\ **Post date:** [January 28, 2008, 8:53pm UTC](https://boards.straightdope.com/t/what-might-have-been-apollos-giant-helicopter/435306/13 "2008-01-28T20:53:36Z")
[QUOTE=brewha] The diameter was greater than 300yds -\> 900’ [/QUOTE] But further down in the article, it says "It would be a monster. The rotor diameter would be over 120 meters (400 feet). " Maybe someone got their feet mixed with their yards. > [@brewha](#): > > Well, you have to think about the size of the rotor. If each blade is 450’ long, the tips would be traveling at 800 MPH at just 25 RPM. > > I wonder what the rotor speed would be to hover. “The rotors would not have to turn very fast by helicopter standards, only about once per second. But even that would result in the advancing rotor tip approaching the speed of sound.” It’s not clear if that is hover speed or transport speed. ---
**Author:** ![OtakuLoki](https://avatars.discourse-cdn.com/v4/letter/o/ac8455/32.png) [@OtakuLoki](https://boards.straightdope.com/u/OtakuLoki)\ **Post date:** [January 28, 2008, 8:55pm UTC](https://boards.straightdope.com/t/what-might-have-been-apollos-giant-helicopter/435306/14 "2008-01-28T20:55:54Z")
FWIW, a football field is only 100 yards long, not 300. I think that’s the source of the confusion. ---
**Author:** ![Ogre](https://avatars.discourse-cdn.com/v4/letter/o/ecb155/32.png) [@Ogre](https://boards.straightdope.com/u/Ogre)\ **Post date:** [January 28, 2008, 9:04pm UTC](https://boards.straightdope.com/t/what-might-have-been-apollos-giant-helicopter/435306/15 "2008-01-28T21:04:13Z")
[QUOTE=OtakuLoki] FWIW, a football field is only 100 yards long, not 300. I think that’s the source of the confusion. [/QUOTE] Yup. The diameter would be over 300’, not 900’. But what a fucking spectacle that beast would be, huh? I bet it’d sound like the wrath of God. Let’s do it! 🙂 ---
**Author:** ![brewha](https://avatars.discourse-cdn.com/v4/letter/b/91b2a8/32.png) [@brewha](https://boards.straightdope.com/u/brewha)\ **Post date:** [January 28, 2008, 9:14pm UTC](https://boards.straightdope.com/t/what-might-have-been-apollos-giant-helicopter/435306/16 "2008-01-28T21:14:24Z")
Ya know, I double checked my numbers after I was called on it too. I watch football. I know that the middle of the field is the 50 yd line and that there’s 10 yds of endzone at each end. So yeah - 120 yds = 360’ So, 6.4 MPH for every RPM - which is about 110RPM for the tips to approach mach one in a hover. But, if the heli wanted to be able to fly forward, the rotor speed would have to be less so the advancing tip wouldn’t break the sound barrier. ---
**Author:** ![Tuckerfan](https://avatars.discourse-cdn.com/v4/letter/t/eada6e/32.png) [@Tuckerfan](https://boards.straightdope.com/u/Tuckerfan)\ **Post date:** [January 29, 2008, 8:44pm UTC](https://boards.straightdope.com/t/what-might-have-been-apollos-giant-helicopter/435306/17 "2008-01-29T20:44:59Z")
[List of the largest helicopters.](http://www.aerospaceweb.org/question/helicopters/q0284.shtml) Interesting to note with the largest: > [@](#): > > Only two V-12 prototypes were built, yet despite its amazing size and lifting power, the design was considered a failure by its manufacturer and Soviet authorities. The V-12 was simply too big and difficult to maneuver to be a practical machine. A production model would have been called the Mi-12, but these plans were cancelled following evaluation of the two test vehicles. One of the V-12 prototypes was retired to the Russian Air Force Museum in Monino while the second is reportedly housed at the Mil factory near Moscow. ---
**Author:** ![Musicat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/musicat/32/20189_2.png) [@Musicat](https://boards.straightdope.com/u/Musicat)\ **Post date:** [January 29, 2008, 9:38pm UTC](https://boards.straightdope.com/t/what-might-have-been-apollos-giant-helicopter/435306/18 "2008-01-29T21:38:21Z")
**Tuckerfan:** “Only two V-12 prototypes were built, yet despite its amazing size and lifting power, the design was considered a failure by its manufacturer and Soviet authorities.” – sounds like something Bruce McCall would draw. Ever seen his art work (Natl Lampoon, New Yorker)? I think he drew something like this, called the “Zud”. A crease in the blueprints caused a crease in the fuselage because no line manager wanted to admit to a mistake.