[Helobubbas] Here Is Our First Clear Look At Chinas Z-20F Seahawk Helicopter Clone (Updated)

andy.cain at comcast.net andy.cain at comcast.net
Wed Oct 16 14:31:42 PDT 2019


"Blade? That's not a blade, this is a blade!" (with apologies to Crocodile
Dundee).

This issue on number of blades was a boring day, extra credit, bonus
discussion back in the dim-times when teaching aerodynamics at HS-10. . .
Particularly when the Brits added a blade to the tail rotor of the Westland
Sea King.

Good answers can be found here
https://physics.stackexchange.com/questions/89752/number-of-blades-in-a-heli
copter-rotor

 

 

From: HELOBUBBAS <helobubbas-bounces at nhahistoricalsociety.org> On Behalf Of
David Suesz
Sent: Wednesday, October 16, 2019 10:32 AM
To: Rawson Mordhorst <rmordhorst at comcast.net>; HELOBUBBAS
<helobubbas at nhahistoricalsociety.org>
Subject: Re: [Helobubbas] Here Is Our First Clear Look At Chinas Z-20F
Seahawk Helicopter Clone (Updated)

 

That's correct, both the H-3 and S-61 had that same metal blade, based on a
pre-WW2 NACA airfoil. I once flew the Westland Sea King, with composite
blades, and it was pretty smooth, the airframe being under 200 hours time
may have been a factor. During my time the H-3 was fitted with inertial
dampers, similar to the S-61, but compatible with blade fold. It got
smoother then. Carson has been making a composite blade, based on a modern
airfoil. Last I heard at least one of Marine One's birds had been fitted
with them. They also now have a tail rotor blade.


David Suesz

  _____  

From: HELOBUBBAS <helobubbas-bounces at nhahistoricalsociety.org
<mailto:helobubbas-bounces at nhahistoricalsociety.org> > on behalf of Rawson
Mordhorst <rmordhorst at comcast.net <mailto:rmordhorst at comcast.net> >
Sent: Wednesday, October 16, 2019 12:01 PM
To: HELOBUBBAS <helobubbas at nhahistoricalsociety.org
<mailto:helobubbas at nhahistoricalsociety.org> >
Subject: Re: [Helobubbas] Here Is Our First Clear Look At Chinas Z-20F
Seahawk Helicopter Clone (Updated) 

 

The H-3s I flew had metal spars with the attached pockets which were also of
metal, as was the blade tip, one of which I have on the wall in the
basement.

 

On October 16, 2019 at 5:34 AM Marc Liebman <marc at marcliebman.com
<mailto:marc at marcliebman.com> > wrote: 

If I remember correctly, the H-3 blades were honeycomb cores in separate
"pockets" with some kind of composite covering.  All of them were bonded to
an alloy spar charged with nitrogen.  The BIM monitors on the hub was a
preflight item. 

Sent from my iPhone





On Oct 15, 2019, at 9:01 PM, "kblack1967 at gmail.com
<mailto:kblack1967 at gmail.com> " <kblack1967 at gmail.com
<mailto:kblack1967 at gmail.com> > wrote: 

I suspect blade material is at play here too.  The H-3 had metal blades
didn't they?  Modern stuff is all composite.. except for the KMAX.. which
are still Wood.  Construction varies but the materials and shapes have come
a long long way since even the 80s. 

 

From: HELOBUBBAS <helobubbas-bounces at nhahistoricalsociety.org
<mailto:helobubbas-bounces at nhahistoricalsociety.org> > On Behalf Of Marc
Liebman
Sent: Tuesday, October 15, 2019 6:54 PM
To: HELOBUBBAS <helobubbas at nhahistoricalsociety.org
<mailto:helobubbas at nhahistoricalsociety.org> >
Subject: Re: [Helobubbas] Here Is Our First Clear Look At Chinas Z-20F
Seahawk Helicopter Clone (Updated)

 

This makes a lot of sense other than the complexity/weight of 5 vs. 4
blades.  I have a lot of time in the H-2 (4 blades) and H-3s (5 blades).
The H-2 was smooth as a baby if you could ever get the blades in track.  The
H-3's  I flew (A/D/G/H) all seemed to vibrate and shake, it was only a
matter of degree or that it was a helicopter.   I don't remember one/rev's
but the H-3s vibrated a lot.  Could have been the age of the blades.    

  

Marc Liebman 

Author of:

Cherubs 2

Big Mother 40

Render Harmless

Forgotten

Inner Look

Moscow Airlift

The Simushir Island Incident (to be released in 2019)

 

Member of:

The Author's Guild

Military Writers Society of America

Association of Texas Authors

North American Snowsport Journalists Association

-- 

  

  

From: HELOBUBBAS <helobubbas-bounces at nhahistoricalsociety.org
<mailto:helobubbas-bounces at nhahistoricalsociety.org> > on behalf of
"kblack1967 at gmail.com <mailto:kblack1967 at gmail.com> " <kblack1967 at gmail.com
<mailto:kblack1967 at gmail.com> >
Reply-To: HELOBUBBAS <helobubbas at nhahistoricalsociety.org
<mailto:helobubbas at nhahistoricalsociety.org> >
Date: Tuesday, October 15, 2019 at 8:01 PM
To: 'HELOBUBBAS' <helobubbas at nhahistoricalsociety.org
<mailto:helobubbas at nhahistoricalsociety.org> >
Subject: Re: [Helobubbas] Here Is Our First Clear Look At Chinas Z-20F
Seahawk Helicopter Clone (Updated) 

 

My theory talking to a lot of people over the years is 4 bladed systems seem
to be more prone to vibration.  Look at all the hoops Sikorsky had to jump
through to deal with them in the 60.  There are several absorbers embedded
in the aircraft in addition to the nitrogen charged blade dampers.  Not sure
how the Puma gets away with 4 blades but as someone who has flown them for
years the dampers are not nitrogen charged and are pretty "loose" in their
damping.  Starting one you wonder if you are going to flop over they wobble
so bad before things get in sync.  In flight though if things are tracked
and balanced right they are just fine.  The Super Puma 332 came out about
the same time as the 60 and also has 4 blades but uses elastomeric straps
instead of dampers, at least on L1s and newer.  They don't wobble around on
start and also seem pretty smooth.  I have never flown or been in a H-3
/S-61 in flight but hear when things are right they are pretty smooth.  The
AW 139 is 5 blades, very smooth.  Bunch of other modern stuff uses odd blade
counts and it seems to work well as it would seem the opposite quadrants
can't create some vibe of their own, 1 per 2 per.  The EC225 I just finished
training in is smooth until you get it up near VH then it starts getting
sort of harsh or rough, but not like a 1 per, 2 per or such, more of a
increased overall vibration.  Maybe the Chinese were looking at other modern
aircraft and decided their lift might be better with 5 and vibration
challenges less.  Frankly I would love to see how a 60 or a S-92 would do
with a well designed 5 blade head. 

 

From: HELOBUBBAS <helobubbas-bounces at nhahistoricalsociety.org
<mailto:helobubbas-bounces at nhahistoricalsociety.org> > On Behalf Of Marc
Liebman
Sent: Tuesday, October 15, 2019 5:26 PM
To: retiredreunionmgr at navalhelicopterassn.org
<mailto:retiredreunionmgr at navalhelicopterassn.org> ; HELOBUBBAS
<helobubbas at nhahistoricalsociety.org
<mailto:helobubbas at nhahistoricalsociety.org> >
Cc: Killer <ray.doggett at virgin.net <mailto:ray.doggett at virgin.net> >
Subject: Re: [Helobubbas] Here Is Our First Clear Look At Chinas Z-20F
Seahawk Helicopter Clone (Updated)

 

Maybe I missed something, but the 60Bs and 60Hs I flew had four bladed
heads.  The PLAN copy of the H-60 has five.  So the question is why?

 

Is it blade area to give more carrying capacity, reduce blade loading to get
more speed, or is airfoil construction capabilities limiting airfoil shape?

 

Marc Liebman

Author of:

Cherubs 2

Big Mother 40

Render Harmless

Forgotten

Inner Look

Moscow Airlift

The Simushir Island Incident (to be released in 2019)

 

Member of:

The Author's Guild

Military Writers Society of America

Association of Texas Authors

North American Snowsport Journalists Association

-- 

 

 

From: HELOBUBBAS <helobubbas-bounces at nhahistoricalsociety.org
<mailto:helobubbas-bounces at nhahistoricalsociety.org> > on behalf of "Michael
G. Brattland" <retiredreunionmgr at navalhelicopterassn.org
<mailto:retiredreunionmgr at navalhelicopterassn.org> >
Organization: www.nhahistoricalsociety.org
<http://www.nhahistoricalsociety.org> 
Reply-To: "retiredreunionmgr at navalhelicopterassn.org
<mailto:retiredreunionmgr at navalhelicopterassn.org> "
<retiredreunionmgr at navalhelicopterassn.org
<mailto:retiredreunionmgr at navalhelicopterassn.org> >, HELOBUBBAS
<helobubbas at nhahistoricalsociety.org
<mailto:helobubbas at nhahistoricalsociety.org> >
Date: Tuesday, October 15, 2019 at 4:46 PM
To: HELOBUBBAS <helobubbas at nhahistoricalsociety.org
<mailto:helobubbas at nhahistoricalsociety.org> >
Cc: Killer <ray.doggett at virgin.net <mailto:ray.doggett at virgin.net> >
Subject: [Helobubbas] Here Is Our First Clear Look At Chinas Z-20F Seahawk
Helicopter Clone (Updated)

 

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