MD Helicopters MD 564
Joined: Aug 2000
Posts: 2,111
Likes: 118
Well looks like it will outfit a 350B2 which will make life interesting out there. Most things `I have to lift are between 500 to 1000 kgs . So the D model will lift the former and the 350 the latter
"Outlift"?
"Outlift"?
Last edited by Pilot DAR; 11th March 2026 at 01:00. Reason: Maybe a typo....
Joined: Dec 2007
Posts: 411
Likes: 14
From: Ireland
Here is a little history on the four blade tail rotor on the 500 series.
This was the initial four blade tail rotor fitted to the OH-6A "Quiet One" experimental helicopter. Blade angles are set at 75 degrees/105 degrees and this was the set up that proved quietest. They also tested a 90/90 and 60/120 set up but neither were quieter. In "Quiet Mode" the rotor RPM was reduced to 67%. Frank Robinson was the chief engineer on this tail rotor system.
Testing on the "Quiet One" also revealed a significant improvement in various regimes of flight when the RPMs were at 100%. This led to the OH-6C which was fitted with the four blade tail rotor and five blade main head from the "Quiet One" along with a C-20 engine. This airframe is the father of the high performance 500 series of T-Tail machines (500D and 530F), I reckon.
This is the first 500D four blade tail rotor on an early production airframe. They didn't have a gear box ready for testing initially and fitted the old "Quiet One" gear box instead. Tail rotor authority was not brilliant by all accounts with the reduced RPM but apparently it was QUIET! The noise reduction with the standard 500D four blade system is impressive if you ever get the chance to hear one live.
The four blade tail rotor fitted to the current Mission Enhanced Little Bird. Canted at 10 degrees, they initially tested it at an angle of 20 degrees. I don't believe this was designed with lower noise emissions in mind but higher performance. The Block III MELB is due to get a new tail rotor that rotates in the opposite direction, I understand.
The new four blade tail rotor on the MD564. Again, this is a high performance rotor system as opposed to an effort to quieten the noise output. However, it's design will probably draw from previous testing so might be a bit quieter than the 530F tail rotor system. (MD Helicopters photo) . I believe a four blade tail rotor for the 530F has been on the drawing board for some years now but was never flown, as far as I know. This 564 tail rotor may be based on that original design.
This was the initial four blade tail rotor fitted to the OH-6A "Quiet One" experimental helicopter. Blade angles are set at 75 degrees/105 degrees and this was the set up that proved quietest. They also tested a 90/90 and 60/120 set up but neither were quieter. In "Quiet Mode" the rotor RPM was reduced to 67%. Frank Robinson was the chief engineer on this tail rotor system.
Testing on the "Quiet One" also revealed a significant improvement in various regimes of flight when the RPMs were at 100%. This led to the OH-6C which was fitted with the four blade tail rotor and five blade main head from the "Quiet One" along with a C-20 engine. This airframe is the father of the high performance 500 series of T-Tail machines (500D and 530F), I reckon.
This is the first 500D four blade tail rotor on an early production airframe. They didn't have a gear box ready for testing initially and fitted the old "Quiet One" gear box instead. Tail rotor authority was not brilliant by all accounts with the reduced RPM but apparently it was QUIET! The noise reduction with the standard 500D four blade system is impressive if you ever get the chance to hear one live.
The four blade tail rotor fitted to the current Mission Enhanced Little Bird. Canted at 10 degrees, they initially tested it at an angle of 20 degrees. I don't believe this was designed with lower noise emissions in mind but higher performance. The Block III MELB is due to get a new tail rotor that rotates in the opposite direction, I understand.
The new four blade tail rotor on the MD564. Again, this is a high performance rotor system as opposed to an effort to quieten the noise output. However, it's design will probably draw from previous testing so might be a bit quieter than the 530F tail rotor system. (MD Helicopters photo) . I believe a four blade tail rotor for the 530F has been on the drawing board for some years now but was never flown, as far as I know. This 564 tail rotor may be based on that original design.
Last edited by 500 Fan; 13th March 2026 at 10:52.
Fleet Manager
Joined: Aug 2006
Aviation Qualifications: CPL
Posts: 7,083
Likes: 2,939
From: Ontario, Canada
The "Quite One" 500P was a Vietnam era project to produce a helicopter capable of night time clandestine activity. It included the four blade tail rotor we've been discussing and a ducted exhaust. Only a few were made, and served, and one was actually returned to being a regular, civil 500C, and operated for some time by a Washington State police force. In military operation, it looked like this: If I recall correctly, it was the first 500 series with the five bladed main rotor.
Thread drift, but I worked a test project years ago for an exhaust improvement, it was a good try, but didn't really make much different, and we did not fly them, project not continued...
Thread drift, but I worked a test project years ago for an exhaust improvement, it was a good try, but didn't really make much different, and we did not fly them, project not continued...
Joined: Jan 2010
Posts: 605
Likes: 12
From: UK
Let’s see how this goes. The example in Atlanta will be returned to the 530 spec it was built with and a real 564 will be built later in the year for test flights. Based on 500/530 civil market sales in recent years, the 564 likely needs a military order to underwrite the development cost
Joined: Aug 2000
Posts: 2,111
Likes: 118
Just realized from the figures it cant lift more than 2000lbs on the hook so a bit of a waste of time for USL work. Now if it could lift to what they say .................
Last edited by Pilot DAR; 22nd March 2026 at 21:43. Reason: typos
