Why did they settle on the 3-blade configuration? Wouldn't a 4-bladed
system allow for a smaller footprint on the ground (or ship)? Or is
there too much thrust loss involved?

"Don McIntyre" > wrote in message
oups.com...
> Why did they settle on the 3-blade configuration? Wouldn't a 4-bladed
> system allow for a smaller footprint on the ground (or ship)? Or is
> there too much thrust loss involved?

I would suspect it is a compromise due to the amount of force that has to be
applied through comparatively small components and the strength of the
materials out of which those components can be built.
--
Andrew Chaplin
SIT MIHI GLADIUS SICUT SANCTO MARTINO
(If you're going to e-mail me, you'll have to get "yourfinger." out.)

"Don McIntyre" > wrote:

>Why did they settle on the 3-blade configuration? Wouldn't a 4-bladed
>system allow for a smaller footprint on the ground (or ship)? Or is
>there too much thrust loss involved?

Well, you can bet your arse that all configs were considered,
number of blades, length pitch width of blades, RPM range etc
etc...That a/c is a real departure from the conventional and must
have been a real headache to design and proove. I hope that they
now have a safe aircraft, they sure had their teething problems
didn't they?...
--

-Gord.
(use gordon in email)

Don McIntyre wrote:
> Why did they settle on the 3-blade configuration? Wouldn't a 4-bladed
> system allow for a smaller footprint on the ground (or ship)? Or is
> there too much thrust loss involved?
>

I would think folding 3 blades would be easier and lighter than
folding 4.

Dan, U.S. Air Force, retired

"Don McIntyre" > wrote in message
oups.com...
> Why did they settle on the 3-blade configuration? Wouldn't a 4-bladed
> system allow for a smaller footprint on the ground (or ship)? Or is
> there too much thrust loss involved?

More blades = less efficiency.

Shorter blades = less efficiency in vertical flight.

They probably couldn't have absorbed the performance loss from both
increasing the number of blades and reducing blade length.

KB

Kyle Boatright wrote:
> "Don McIntyre" > wrote in message
> oups.com...
> > Why did they settle on the 3-blade configuration? Wouldn't a 4-bladed
> > system allow for a smaller footprint on the ground (or ship)? Or is
> > there too much thrust loss involved?
>
> More blades = less efficiency.
>
> Shorter blades = less efficiency in vertical flight.
>
> They probably couldn't have absorbed the performance loss from both
> increasing the number of blades and reducing blade length.
>
> KB
How does more blades equal less efficiency? If that is true why do all
current Helicopters use 4-5 blades instead of two like the legacy
systems of the Huey and Cobra? Why do all modern turbo-props have more
then two blades? Somthing sounds off here. Guesses are like.... Anyone
actually involved in the engineering of the V-22 or at least privy to
some of the original evaluation documentation?
Reed

"Reed Judd-Dyer" > wrote in message
oups.com...
>
> Kyle Boatright wrote:
>> "Don McIntyre" > wrote in message
>> oups.com...
>> > Why did they settle on the 3-blade configuration? Wouldn't a 4-bladed
>> > system allow for a smaller footprint on the ground (or ship)? Or is
>> > there too much thrust loss involved?
>>
>> More blades = less efficiency.
>>
>> Shorter blades = less efficiency in vertical flight.
>>
>> They probably couldn't have absorbed the performance loss from both
>> increasing the number of blades and reducing blade length.
>>
>> KB
> How does more blades equal less efficiency? If that is true why do all
> current Helicopters use 4-5 blades instead of two like the legacy
> systems of the Huey and Cobra? Why do all modern turbo-props have more
> then two blades? Somthing sounds off here. Guesses are like.... Anyone
> actually involved in the engineering of the V-22 or at least privy to
> some of the original evaluation documentation?
> Reed

More blades equals less efficiency for several reasons. One is that the
more blades you have, the dirtier the air becomes. Rotor and prop blades
like undisturbed air best. Also, you balance the number of blades and their
diameter against the HP from the engine. More blades = less blade length =
lower aspect ratio = lower efficiency.

Early helicopters needed the most efficient blade/power system possible just
to get off the ground. That resulted in two bladed rotors with long blade
length. As engines came along with significantly more HP, designers could
trade-off aerodynamic efficiency for packaging efficiency and create a
helicopter with adequate performance and reasonable size for the delivered
performance.

Aircraft with turboprop powertrains have multiple blades because those
designers have to make compromises too. There are clearance issues to deal
with (ground clearance, fuselage clearance, prop to prop clearance). There
are tip speed issues (you don't really want to take prop tips over .9 mach
if you can help it). And there are dynamic issues where a fast turning big
prop generates tremendous forces in shear, bending, and precession.. All of
those things drive designers towards a smaller diameter prop. So, the
designer compromises those packaging needs versus aerodynamic efficiency,
and voila... Multi-bladed prop's.

If more blades was a better solution, you'd see Cessna 150's with 20 blade
prop's, because those little airplanes need all the help they can get...

KB

Dan > wrote:

>Don McIntyre wrote:
>> Why did they settle on the 3-blade configuration? Wouldn't a 4-bladed
>> system allow for a smaller footprint on the ground (or ship)? Or is
>> there too much thrust loss involved?
>>
>
> I would think folding 3 blades would be easier and lighter than
>folding 4.
>
>Dan, U.S. Air Force, retired

?? Folding ??
--

-Gord.
(use gordon in email)

Kyle Boatright wrote:
> "Reed Judd-Dyer" > wrote in message
> oups.com...
> >
> > Kyle Boatright wrote:
> >> "Don McIntyre" > wrote in message
> >> oups.com...
> >> > Why did they settle on the 3-blade configuration? Wouldn't a 4-bladed
> >> > system allow for a smaller footprint on the ground (or ship)? Or is
> >> > there too much thrust loss involved?
> >>
> >> More blades = less efficiency.
> >>
> >> Shorter blades = less efficiency in vertical flight.
> >>
> >> They probably couldn't have absorbed the performance loss from both
> >> increasing the number of blades and reducing blade length.
> >>
> >> KB

> > How does more blades equal less efficiency? If that is true why do all
> > current Helicopters use 4-5 blades instead of two like the legacy
> > systems of the Huey and Cobra? Why do all modern turbo-props have more
> > then two blades? Somthing sounds off here. Guesses are like.... Anyone
> > actually involved in the engineering of the V-22 or at least privy to
> > some of the original evaluation documentation?
> > Reed
>
> More blades equals less efficiency for several reasons. One is that the
> more blades you have, the dirtier the air becomes. Rotor and prop blades
> like undisturbed air best. Also, you balance the number of blades and their
> diameter against the HP from the engine. More blades = less blade length =
> lower aspect ratio = lower efficiency.
>
> Early helicopters needed the most efficient blade/power system possible just
> to get off the ground. That resulted in two bladed rotors with long blade
> length. As engines came along with significantly more HP, designers could
> trade-off aerodynamic efficiency for packaging efficiency and create a
> helicopter with adequate performance and reasonable size for the delivered
> performance.
>
> Aircraft with turboprop powertrains have multiple blades because those
> designers have to make compromises too. There are clearance issues to deal
> with (ground clearance, fuselage clearance, prop to prop clearance). There
> are tip speed issues (you don't really want to take prop tips over .9 mach
> if you can help it). And there are dynamic issues where a fast turning big
> prop generates tremendous forces in shear, bending, and precession.. All of
> those things drive designers towards a smaller diameter prop. So, the
> designer compromises those packaging needs versus aerodynamic efficiency,
> and voila... Multi-bladed prop's.
>
> If more blades was a better solution, you'd see Cessna 150's with 20 blade
> prop's, because those little airplanes need all the help they can get...
>
> KB

OK, That jives with research I was doing on ducted fan systems. The
advantage of the duct being that it reduced the "disturbed" air effect,
making them more effecient untill the drag created by the duct zeroed
out the gains. Also helps explain why a two engine tilt-rotor can
verticly lift more then a four engine tilt-prop. Thanks for the clear
answer.
Reed

"Gord Beaman" > wrote in message
...
> Dan > wrote:
>
>>Don McIntyre wrote:
>>> Why did they settle on the 3-blade configuration? Wouldn't a 4-bladed
>>> system allow for a smaller footprint on the ground (or ship)? Or is
>>> there too much thrust loss involved?
>>>
>>
>> I would think folding 3 blades would be easier and lighter than
>>folding 4.
>>
>>Dan, U.S. Air Force, retired
>
> ?? Folding ??
> --
>
> -Gord.
> (use gordon in email)

http://www.paravion.com/products/407-427_blade_fold_kit/407-427_blade_fold_kit.htm

Keith

Reed Judd-Dyer wrote

> How does more blades equal less efficiency?

Those of us that flew rubber band powered contest model
aircraft way back ('40s-'50s) KNOW that the most efficient
propellor has only ONE blade...and a counterweight on the
other side. :-)

Bob Moore

"Keith W" > wrote:

>
>"Gord Beaman" > wrote in message
...
>> Dan > wrote:
>>
>>>Don McIntyre wrote:
>>>> Why did they settle on the 3-blade configuration? Wouldn't a 4-bladed
>>>> system allow for a smaller footprint on the ground (or ship)? Or is
>>>> there too much thrust loss involved?
>>>>
>>>
>>> I would think folding 3 blades would be easier and lighter than
>>>folding 4.
>>>
>>>Dan, U.S. Air Force, retired
>>
>> ?? Folding ??
>> --
>>
>> -Gord.
>> (use gordon in email)
>
>http://www.paravion.com/products/407-427_blade_fold_kit/407-427_blade_fold_kit.htm
>
>Keith
>
Thanks Keith...I thought that Dan was referring to the V-22...I
don't think that it 'has' folding blades does it?...
--

-Gord.
(use gordon in email)

Gord Beaman wrote:
> "Keith W" > wrote:
>
>> "Gord Beaman" > wrote in message
>> ...
>>> Dan > wrote:
>>>
>>>> Don McIntyre wrote:
>>>>> Why did they settle on the 3-blade configuration? Wouldn't a 4-bladed
>>>>> system allow for a smaller footprint on the ground (or ship)? Or is
>>>>> there too much thrust loss involved?
>>>>>
>>>> I would think folding 3 blades would be easier and lighter than
>>>> folding 4.
>>>>
>>>> Dan, U.S. Air Force, retired
>>> ?? Folding ??
>>> --
>>>
>>> -Gord.
>>> (use gordon in email)
>> http://www.paravion.com/products/407-427_blade_fold_kit/407-427_blade_fold_kit.htm
>>
>> Keith
>>
> Thanks Keith...I thought that Dan was referring to the V-22...I
> don't think that it 'has' folding blades does it?...

Yep, it sure does. If you could ever describe an aircraft as folding up
like a pretzel, the V-22 is it:

http://www.globalsecurity.org/military/systems/aircraft/v-22-bld-wing-seq.htm

Jim Carriere > wrote:

>Gord Beaman wrote:
>> "Keith W" > wrote:
>>
>>> "Gord Beaman" > wrote in message
>>> ...
>>>> Dan > wrote:
>>>>
>>>>> Don McIntyre wrote:
>>>>>> Why did they settle on the 3-blade configuration? Wouldn't a 4-bladed
>>>>>> system allow for a smaller footprint on the ground (or ship)? Or is
>>>>>> there too much thrust loss involved?
>>>>>>
>>>>> I would think folding 3 blades would be easier and lighter than
>>>>> folding 4.
>>>>>
>>>>> Dan, U.S. Air Force, retired
>>>> ?? Folding ??
>>>> --
>>>>
>>>> -Gord.
>>>> (use gordon in email)
>>> http://www.paravion.com/products/407-427_blade_fold_kit/407-427_blade_fold_kit.htm
>>>
>>> Keith
>>>
>> Thanks Keith...I thought that Dan was referring to the V-22...I
>> don't think that it 'has' folding blades does it?...
>
>Yep, it sure does. If you could ever describe an aircraft as folding up
>like a pretzel, the V-22 is it:
>

Absolutely amazing!...Sorry Dan, I'm still shaking my head in
amazement...quite an aircraft!.
--

-Gord.
(use gordon in email)

Bob Moore wrote:

> Reed Judd-Dyer wrote
>
> > How does more blades equal less efficiency?
>
> Those of us that flew rubber band powered contest model
> aircraft way back ('40s-'50s) KNOW that the most efficient
> propellor has only ONE blade...and a counterweight on the
> other side. :-)
>
> Bob Moore

A Helo with one blade would have to be the most uncomfortable ride,
until after a minute or so, when it had shook itself to pieces.

Jeremy Thomson

wrote in news:1143609590.585290.233720
@u72g2000cwu.googlegroups.com:

>
> Bob Moore wrote:
>
>> Reed Judd-Dyer wrote
>>
>> > How does more blades equal less efficiency?
>>
>> Those of us that flew rubber band powered contest model
>> aircraft way back ('40s-'50s) KNOW that the most efficient
>> propellor has only ONE blade...and a counterweight on the
>> other side. :-)
>>
>> Bob Moore
>
> A Helo with one blade would have to be the most uncomfortable ride,
> until after a minute or so, when it had shook itself to pieces.
>
> Jeremy Thomson

He did say with "a counterweight on the other side", so balance is not an
issue. This works better on larger, slower turning props, though. I'd hate
to try it on a fast spinning model airplane prop.

Dave in San Diego

In article . com>,
wrote:

> Bob Moore wrote:
>
> > Reed Judd-Dyer wrote
> >
> > > How does more blades equal less efficiency?
> >
> > Those of us that flew rubber band powered contest model
> > aircraft way back ('40s-'50s) KNOW that the most efficient
> > propellor has only ONE blade...and a counterweight on the
> > other side. :-)
> >
> > Bob Moore
>
> A Helo with one blade would have to be the most uncomfortable ride,
> until after a minute or so, when it had shook itself to pieces.

quite a bit less than a minute...

The single-blade prop with counterweight actually worked pretty well in
testing.

Best configuration for the V-22, you ask? In combat, a heap of burning
wreckage or in peace time... a cancelled project piece of scrap metal.
Transitional a/c are inherently dangerous no matter what, and if the
primitive Iraqis can down an Apache how much more vunerable is the
tilt-rotor Osprey... or rather "Easy Prey"?

Imagine an Osprey loaded with troops as it transitions to take off or
land in Iraq. One RPG or heavy MG fire to the rotor system and the US
will be scraping the remains of its troops out of the dirt and sand
with shovels.

Why doesn't someone cancel this flying cemetery already? Like the
F/A-22 seems the number "22" in US inventory= disaster. The Craptor and
Easy Prey need the axe. Cancelling the Craptor will save money while
cancelling Easy Prey will save lives.

Rob

Rob,
I don't understand your point. The same could apply to any "lift"
vehicle. Helos, C-130s, C-17s, H-60s, you name it. The advances in
design, the increase in speed and range over conventional helos seem to
me to make the V-22 a large advance of helos. We've become so
conditioned to our "safe" world that we tend to forget that new
technology does take tme to mature and develop. Some have forgotten
that the F4, F-14 and in particular the Century series jets that many
of we aviation fans have come to know and love had their fair shre of
crashes and developmental disasters before the matured into useable
RELATIVELY safe systems.
Cancelling the V-22 and F-22 leaves us with, what? When the F-35
comes along will you want to cancel that as well? I want our Armed
forces to have the best. What can beat the F-22? Oh, wait, maybe we
should buy Su-30s! I don't think so.

Rob Arndt wrote:
> Best configuration for the V-22, you ask? In combat, a heap of burning
> wreckage or in peace time... a cancelled project piece of scrap metal.
> Transitional a/c are inherently dangerous no matter what, and if the
> primitive Iraqis can down an Apache how much more vunerable is the
> tilt-rotor Osprey... or rather "Easy Prey"?
>
> Imagine an Osprey loaded with troops as it transitions to take off or
> land in Iraq. One RPG or heavy MG fire to the rotor system and the US
> will be scraping the remains of its troops out of the dirt and sand
> with shovels.
>
> Why doesn't someone cancel this flying cemetery already? Like the
> F/A-22 seems the number "22" in US inventory= disaster. The Craptor and
> Easy Prey need the axe. Cancelling the Craptor will save money while
> cancelling Easy Prey will save lives.
>
> Rob
>
This is from the fool who thinks Japan needs ICBMs, nuclear powered
aircraft carriers and nuclear powered submarines to protect itself from
China and North Korea. Then again he also believes a 34 pound weapon is
an excellent E&E choice for downed air crews, the Earth is hollow,
there's a secret still operational Nazi underground U-boat base in
Antarctica.....etc.

Dan, U.S. Air Force, retired

Don,

NONE of those aircraft or helos you mentioned are TRANSITIONAL craft.
The V-22 has a lousy test record that the Marines falsified heavily to
pass the a/c through and it IS a deathtrap in just "being" a
transitional craft.
Transitioning is like being a sitting duck ASKING to be hit in a highly
vunerable moment, far worse than a helo set-down.
I'm not the only person who has voiced this and want the V-22
cancelled.
As for advancements in aviation, this is nothing new. The Germans had
TWO transitional a/c designs during WW2 (from Focke-Achgelis and
Weserflug). Neither were built. The Germans DID, however, have the
Me-321 and 323 Gigant transports- the C-5s of the day able to lift
artillery, tanks, and 100 men and it flew... but no one wanted to be
inside the lumbering monster that was easy prey for Spits in the Med,
despite 10 MG defense!
There are a lot of special forces and other soldiers that don't want to
climb into the V-22 for the same reasons- the a/c is a deathtrap.
BTW, FYI, many believe that the XF-23 was better than the XF-22 but
that the USAF is biased towards Lockheed products- same as Heinkel vs
Messerschmitt. Now its Northrop vs Lockheed Martin- Whatever!
I'm for axing both these aircraft but the am in favor of the F-35 and a
reasonable new air superiority fighter- not some mess that costs the
taxpayer almost $175 million per copy when a new Su-47 and the
Euro-craft cost around $75-80 mil each. Hell, you COULD buy Flankers
for around $50-60 mil each!
And the F/A-22 performance claims are just that-company and USAF
claims. They should have just continued work on the F-16XL and further
F-15 development. The F/A-22 isn't justified at all. It went from F-22
to F/A-22 to naval F/A-22 and now a proposed F/B-22!!!
Gimme a ****ing break... that turkey isn't selling. Axe it!!!

Rob

Rob Arndt wrote:
> Don,
>
> NONE of those aircraft or helos you mentioned are TRANSITIONAL craft.
> The V-22 has a lousy test record that the Marines falsified heavily to
> pass the a/c through and it IS a deathtrap in just "being" a
> transitional craft.
> Transitioning is like being a sitting duck ASKING to be hit in a highly
> vunerable moment, far worse than a helo set-down.
> I'm not the only person who has voiced this and want the V-22
> cancelled.
> As for advancements in aviation, this is nothing new. The Germans had
> TWO transitional a/c designs during WW2 (from Focke-Achgelis and
> Weserflug). Neither were built. The Germans DID, however, have the
> Me-321 and 323 Gigant transports- the C-5s of the day able to lift
> artillery, tanks, and 100 men and it flew... but no one wanted to be
> inside the lumbering monster that was easy prey for Spits in the Med,
> despite 10 MG defense!
> There are a lot of special forces and other soldiers that don't want to
> climb into the V-22 for the same reasons- the a/c is a deathtrap.
> BTW, FYI, many believe that the XF-23 was better than the XF-22 but
> that the USAF is biased towards Lockheed products- same as Heinkel vs
> Messerschmitt. Now its Northrop vs Lockheed Martin- Whatever!
> I'm for axing both these aircraft but the am in favor of the F-35 and a
> reasonable new air superiority fighter- not some mess that costs the
> taxpayer almost $175 million per copy when a new Su-47 and the
> Euro-craft cost around $75-80 mil each. Hell, you COULD buy Flankers
> for around $50-60 mil each!
> And the F/A-22 performance claims are just that-company and USAF
> claims. They should have just continued work on the F-16XL and further
> F-15 development. The F/A-22 isn't justified at all. It went from F-22
> to F/A-22 to naval F/A-22 and now a proposed F/B-22!!!
> Gimme a ****ing break... that turkey isn't selling. Axe it!!!
>
> Rob
>

My point is your opinions on tactics, strategy, individual equipment,
weapons, weapons systems, utility of aircraft etc as posted here over
the years have been way off base and are about as realistic as your
claim Germany defeated a U.S. expeditionary force in Antarctica after
the war. Something about a secret Nazi underground U-boat base in
Antarctica.

Dan, U.S. Air Force, retired

Steve Hix wrote:
> In article . com>,
> wrote:
>
>
>>Bob Moore wrote:
>>
>>
>>>Reed Judd-Dyer wrote
>>>
>>>
>>>>How does more blades equal less efficiency?
>>>
>>>Those of us that flew rubber band powered contest model
>>>aircraft way back ('40s-'50s) KNOW that the most efficient
>>>propellor has only ONE blade...and a counterweight on the
>>>other side. :-)
>>>
>>>Bob Moore
>>
>>A Helo with one blade would have to be the most uncomfortable ride,
>>until after a minute or so, when it had shook itself to pieces.
>
>
> quite a bit less than a minute...
>
> The single-blade prop with counterweight actually worked pretty well in
> testing.
AND if you look at the model planes that are used in the International
U control speed contests, each has only one wing with fuel inside,
powered by an engine with prop of one blade and counterweight, faster
it goes more Cf on fuel in wing to input to engine, which has funnel
type air inlet to carb. Really screams, and speeds of over 230 klm
hour running in a 33meter radius circle about a heavy pivot in the
center.
Year I saw it at Westover, Mass the Aussie team won it by a healthy
margin.. more than 3% faster than old record..

Rather than follow the advice of Henry Jones Sr., Dan couldn't just let
news:qbTWf.2383$IG.2210@dukeread01 on 30 Mar 2006 go.

> Rob Arndt wrote:
>> Best configuration for the V-22, you ask? In combat, a heap of
>> burning wreckage or in peace time... a cancelled project piece of
>> scrap metal. Transitional a/c are inherently dangerous no matter
>> what, and if the primitive Iraqis can down an Apache how much more
>> vunerable is the tilt-rotor Osprey... or rather "Easy Prey"?
>>
>> Imagine an Osprey loaded with troops as it transitions to take off or
>> land in Iraq. One RPG or heavy MG fire to the rotor system and the US
>> will be scraping the remains of its troops out of the dirt and sand
>> with shovels.
>>
>> Why doesn't someone cancel this flying cemetery already? Like the
>> F/A-22 seems the number "22" in US inventory= disaster. The Craptor
>> and Easy Prey need the axe. Cancelling the Craptor will save money
>> while cancelling Easy Prey will save lives.
>>
>> Rob
>>
> This is from the fool who thinks Japan needs ICBMs, nuclear powered
> aircraft carriers and nuclear powered submarines to protect itself
> from China and North Korea. Then again he also believes a 34 pound
> weapon is an excellent E&E choice for downed air crews, the Earth is
> hollow, there's a secret still operational Nazi underground U-boat
> base in Antarctica.....etc.

Delurking.....and this has to be one I do it with....sheesh.

I usually just read because the activity in this group seems more
oriented to air crew than ground crew.

My history - 9 years USMC - former Sergeant of Marines - OV-10D/D+ FLIR
tech - also A-6E IR portion of the TRAM and a squidge of F/A-18 IRDS.

While there are some rather foolish criticisms regarding aircraft
selection and policy, there are some sound ones as well.

When the V-22 program first started going through initial trials, there
were some legitimate, negative reactions to its catastrophic lack of air
worthiness. Additionally, I read several pieces about how the Marine
Corps didn't really want/need the V-22 early on. The general line of
reasoning was that the Corps could break out the old patterns and build 5
to 10 CH-46 helicopters for the price of one V-22. The V-22 also
compared poorly when it came to maintenance hours per flight hour.

Yet the V-22 program was impossible to kill because the manufacturer(s)
had carefully placed enough work in as many congressional districts as
possible. Thus it was impossible to vote against the V-22 without voting
against jobs for the folks at home.

Of course we are now much further down the road and the money already
spent makes it harder to kill a program that fails to perform as
advertised. I'm sure the Corps has bought into the program if for no
other reason than swallowing is an easier process than regurgitation.

IMO, the Osprey was deployed well before prudence should dictate. The
program doesn't have a few bugs to figure out (something every program
has). It has one large bug in the primary mechanism that is supposed to
give the Osprey unique capabilities.

--
Regards,
Dann
Blogging at: http://www.modempool.com/nucleardann/blogspace/blog.htm

A big enough hammer can usually fix anything.