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-   -   If you could design your own rotorcraft... (https://www.pprune.org/rotorheads/590753-if-you-could-design-your-own-rotorcraft.html)

SASless 13th Feb 2017 13:46

The Mad Dawg's are a hoot aren't they!




Originally Posted by 500 Fan (Post 9674546)
MDHC flew a 520N with a six-blade rotorhead back in the early 1990's. That might have been a nice machine to fly. At the moment, a lightly-loaded MH-6M MELB is probably as good as it gets.


500 Fan.


ShyTorque 13th Feb 2017 14:02


Originally Posted by cattletruck (Post 9674432)
I've always thought that with the Fairey Rotodyne concept it could have further been developed to allow the gases from the turboprop engines, with some half decent plumbing, to be squirted out the tips of the rotor blades much like that of a water sprinkler.

CT,

It's already been done and more research is being done on similar systems.

R22 HEAVY 15th Feb 2017 21:55

Two engines, two blades up top and on the tail, chaff and flare, retractable gun pods on sponsons. Retractable undercarriage, colour black on top white underneath.

Kewbick 16th Feb 2017 02:20

If I could design my own rotor-craft, it might look like this:

http://i1047.photobucket.com/albums/...ket/AVX509.jpg

cattletruck 17th Feb 2017 09:50

Actually, I've always thought you could turn the tail rotor of any run-of-the-mill helicopter into a pusher-prop that can reverse pitch its blades on one side during the hover to counteract the torque. That is, it can induce a turning moment around the tail rotor gearbox which can be balanced with cyclic.

PDR1 17th Feb 2017 10:11

The mechanical advantage (leverage) of such a system is minimal, so the stresses in the blade roots and shaft would be huge.

PDR

IFMU 17th Feb 2017 11:39

Years ago I believe Sikorsky had a pivoting tail rotor which swiveled to provide thrust in forward flight, using the vertical tail for anti torque at high speed. The experiment must not have warranted pursuing the technology, as the concept has disappeared. I believe there were a lot of vibe issues. If I was to design my own rotorcraft it would look a lot like the X2.

SASless 17th Feb 2017 20:48

I would like to see this all dolled up into a nice Corporate style paint scheme and interior.



https://s-media-cache-ak0.pinimg.com...f1b0bd4e77.jpg

Cpt_Pugwash 17th Feb 2017 22:49

A highly developed Gazelle... :)



http://upload.wikimedia.org/wikipedi...BubbleShip.jpg

https://www.google.co.uk/url?sa=i&rc...87461276610225

JohnDixson 18th Feb 2017 03:16

Cattletruck: Here you are:

http://www.sikorskyarchives.com/imag...66%20X%205.jpg

SASless 18th Feb 2017 12:46

I did not know the SK Engineering Department used mind altering substances to that degree!:uhoh:

JohnDixson 18th Feb 2017 14:51

Right, SAS! Someone cut off their supply as you'll notice we did not pursue this approach.

Noticed also that so far, no poster has mentioned a desire for a rotor that the pilot stops in flight, after which it behaves like a four bladed X-Wing which utilizes boundary layer control ( the RSRA/X-Wing design ). That was going to demand an Act of Faith on the part of the test pilot who pushed the ROTOR STOP button the first time up at speed.

( Thanks to Senior Pilot for putting up the pics in place of the link )

cattletruck 19th Feb 2017 10:18

Awesome pics folks, first time I've seen them, thanks.

A pusher prop would also negate the need for using more forward cyclic at full speed and keep the airframe flatter with the airflow.

Seems like autorotations could get interesting with such a configuration especially the end bit, however I guess if you had enough height you could use the windmilling effect of the pusher prop to drive the MR-RPM back up again if it got too low.

JohnDixson 19th Feb 2017 11:54

"You could use the windmilling effect of the pusher prop to drive the MR-RPM backup again.."

Not sure about that. You may recall the Lockheed AH-56 Cheyenne, which had both a tail rotor AND a pusher prop. Had a single GE T-64 engine. If I recall, there was an auto feather device for the pusher prop in the event of an engine failure. Perhaps someone from Lockheed can comment.

JohnDixson 19th Feb 2017 14:53

AH-56 Pusher
 
Catlletruck, I found this AH-56 Flight Test Evaluation by the US Army Engr Flight Activity troops:
http://www.dtic.mil/dtic/tr/fulltext/u2/771914.pdf

Page 28 has some info re engine failure characteristics. For everyone else, it provides a glimpse into the AH-56 flying qualities and flight envelope limitations. This same group did an evaluation of the S-67 a few years later. The 67 had two engines.

NutLoose 19th Feb 2017 15:45

JohnDixson

Already been tried as such

https://www.gizmodo.com.au/2013/11/t...lmost-a-thing/

In films there was the one in The 6th Day that converted to a normal wing config in flight.

http://stargazer2006.online.fr/vario...ispercraft.htm

JohnDixson 19th Feb 2017 16:30

NL, I noticed as to the second link:

" The movie's flying sequences were all done using computer graphics. " Indeed!

As to the first link, I must admit to never hearing mention of it, at least from 1966 to 2005, but perhaps Nick Lappos has. The possibility ( probability?? ) of a dynamics issue or two ( pun intended ) automatically come to mind.

NutLoose 19th Feb 2017 23:05

Anyone mentioned the ejection seat? The US during Vietnam were attempting to develop a bang seat that would deeply rotors and be then flown by the ejectee away from te crash site.

JohnDixson 20th Feb 2017 00:34

Like this?

https://m.youtube.com/watch?v=jLhZN7fTwQQ


SASless 20th Feb 2017 01:44

Dixson....you SOB!

You owe me a new Keyboard!

I watched that video and found early parts of of the narrative a bit funny.....but when the Guy said.....for purposes of this Test the Seats were occupied by Dummies....I formed a Mental Image of what it would look like if the Rotor Separation and Ejection system was ever tested in flight.....Well....I just wasted some very good Single Malt Whisky cleaning the iMac Screen and doing a deep soak of what I hope is liquid proof Keyboard. Dang...but that stuff burns coming out the nostrils!:ok:

Somehow "Dummies" just seemed so right somehow!

Perhaps I really was not cut out to be a Sikorsky Test Pilot!


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