AH64 Apache - can they roll?

[Taffer]

dr_gn said:

Beats me how anyone in their right mind would step in to a Robinson helicopter. They look like a school design project gone wrong. Even the control column looks like a bent paper clip.

I know what you mean - their low cost compared to turbine choppers is the only real reason they are used for training and private flying. The MOD, for whom cost isn't a major factor, wisely skips the Robinson and puts pilots into Single turbine Squirrels after fixed-wing Elementary Flying Training.


EDIT: Should have said that you experience 0G at the top of the loop - you'll get a bit of -G if you're not perfect though, and discover what you left lying on the cockpit floor!

Edited by Taffer on Tuesday 28th July 21:37

[Quick silver]

Not a problem for the Apache, boeing joined up with AgustaWestland (now GKN) to assist development/assembly.

I'll probably get a lot of flak for this, but I'm pretty much sure that the Lynx (aka Westland) was the first helicopter able to loop without cutting off it's own tail - mainly down to the design of the short/rigit rotor blade.

Edited by Quick silver on Wednesday 29th July 10:46

[dr_gn]

Quick silver said:

I'll probably get a lot of flak for this, but I'm pretty much sure that the Lynx (aka Westland) was the first helicopter able to loop without cutting off it's own tail - mainly down to the design of the short/rigit rotor blade.

Edited by Quick silver on Wednesday 29th July 10:46

Quick search:

"In 1968 a standard CH-53A completed a prolonged series of loops and rolls"

Lynx was later than that.

[Eric Mc]

I've seen film footage of a CH-53 rolling. From what I recall it was a barrel roll which should have kept the g's positive.

This is the series of 1968 tests.


http://www.youtube.com/watch?v=VC2E8RJE3Jo

Edited by Eric Mc on Wednesday 29th July 11:21

[FourWheelDrift]

Here's the S-67 Blackhawk prototype doing a full loop in the early 70s

@ around 1m10s - http://www.youtube.com/watch?v=iniXBYFLybs

The S-67 crashed at the 1974 Farnborough show after successfully performing a barrel roll at low altitude, it then did another but was now at too low an altitude and unable to recover in time. I remember reading all about it in a magazine in the 1980s.

[Quick silver]

FourWheelDrift said:

Here's the S-67 Blackhawk prototype doing a full loop in the early 70s

@ around 1m10s - http://www.youtube.com/watch?v=iniXBYFLybs

The S-67 crashed at the 1974 Farnborough show after successfully performing a barrel roll at low altitude, it then did another but was now at too low an altitude and unable to recover in time. I remember reading all about it in a magazine in the 1980s.

The original Lynx design was in 1969, but due to the french pulling out of their side of the co-production agreement, the first Lynx flew in 1971 - well before the Blackhawk that flew as a prototype in 1974, went into production in 1976 but didn't make any deliveries until 1979......I was in the forces in the Early 80's & rember the blackhawk as being a new helicopter.

[Eric Mc]

The Blackhawk that crashed at Farnborough in 1974 was nothing to do with the Blackhawk that entered service with the US Army in the 1980s.

The 70s Blackhawk was a gunship helicopter and never entered production.

[FourWheelDrift]

Quick silver said:

FourWheelDrift said:

Here's the S-67 Blackhawk prototype doing a full loop in the early 70s

@ around 1m10s - http://www.youtube.com/watch?v=iniXBYFLybs

The S-67 crashed at the 1974 Farnborough show after successfully performing a barrel roll at low altitude, it then did another but was now at too low an altitude and unable to recover in time. I remember reading all about it in a magazine in the 1980s.

The original Lynx design was in 1969, but due to the french pulling out of their side of the co-production agreement, the first Lynx flew in 1971 - well before the Blackhawk that flew as a prototype in 1974, went into production in 1976 but didn't make any deliveries until 1979......I was in the forces in the Early 80's & rember the blackhawk as being a new helicopter.

Perhaps you could look at the video clip first

[Taffer]

Quick silver said:

FourWheelDrift said:

Here's the S-67 Blackhawk prototype doing a full loop in the early 70s

@ around 1m10s - http://www.youtube.com/watch?v=iniXBYFLybs

The S-67 crashed at the 1974 Farnborough show after successfully performing a barrel roll at low altitude, it then did another but was now at too low an altitude and unable to recover in time. I remember reading all about it in a magazine in the 1980s.

The original Lynx design was in 1969, but due to the french pulling out of their side of the co-production agreement, the first Lynx flew in 1971 - well before the Blackhawk that flew as a prototype in 1974, went into production in 1976 but didn't make any deliveries until 1979......I was in the forces in the Early 80's & rember the blackhawk as being a new helicopter.

I think you're getting confused between the S-67 Blackhawk, which was a gunship/troop carrier (think American Hind) that never made it into production, and the UH-60 Black Hawk, the utility helicopter that is widely used by US Forces and her allies.

S-67:


UH-60:

[Conian]

Blue Thunder could do loops.
It confused the heck out of Malcolm McDowell.

[Quick silver]

Taffer said:

Quick silver said:

FourWheelDrift said:

Here's the S-67 Blackhawk prototype doing a full loop in the early 70s

@ around 1m10s - http://www.youtube.com/watch?v=iniXBYFLybs

The S-67 crashed at the 1974 Farnborough show after successfully performing a barrel roll at low altitude, it then did another but was now at too low an altitude and unable to recover in time. I remember reading all about it in a magazine in the 1980s.

The original Lynx design was in 1969, but due to the french pulling out of their side of the co-production agreement, the first Lynx flew in 1971 - well before the Blackhawk that flew as a prototype in 1974, went into production in 1976 but didn't make any deliveries until 1979......I was in the forces in the Early 80's & rember the blackhawk as being a new helicopter.

I think you're getting confused between the S-67 Blackhawk, which was a gunship/troop carrier (think American Hind) that never made it into production, and the UH-60 Black Hawk, the utility helicopter that is widely used by US Forces and her allies.

Both Helicicopters are Sikorsky & both were developted from the same blueprint, the later UH-60 being the production choice.....I see little reason in arguing the point over a prototype that never actually went into production - S-69 variants are mute.

[Hammerwerfer]

Eric Mc said:

I've seen film footage of a CH-53 rolling. From what I recall it was a barrel roll which should have kept the g's positive.

This is the series of 1968 tests.

Wow! Took some balls to do that!

[FourWheelDrift]

Quick silver said:

Both Helicicopters are Sikorsky & both were developted from the same blueprint, the later UH-60 being the production choice.....I see little reason in arguing the point over a prototype that never actually went into production - S-69 variants are mute.

What blueprint? Other than being made by the same manufacturer they have nothing in common except the name which was reused after the S-67 gunship was cancelled.

[Quick silver]

FourWheelDrift said:

Quick silver said:

Both Helicicopters are Sikorsky & both were developted from the same blueprint, the later UH-60 being the production choice.....I see little reason in arguing the point over a prototype that never actually went into production - S-69 variants are mute.

What blueprint? Other than being made by the same manufacturer they have nothing in common except the name which was reused after the S-67 gunship was cancelled.

OK, I have no intention of hijacking the thread, however - The Black Hawk UH-60 was born out of the Sikorsky S-70 project designed to the United States Army's Utility Tactical Transport Aircraft System (UTTAS) specification that began in the latter part of the 1960's.

Sikorsky preceded S-70 prototype construction with a set of five demonstrators, based on modified S-61 and S-65 transport helicopters plus the experimental S-67 gunship, to validate UTTAS technologies.

Just done a bit of digging & found this under S-70 origins, second paragraph : http://www.vectorsite.net/avs70_1.html


Please trust me, I know what I'm talking about here.

[Eric Mc]

I assume things like rotors and rotor heads might have been based on the same technology?

However, the final production utility Blackhawk is a very different beast to the gunship of the mid 1970s.

Has anyone ever rolled one of the current Blackhawks?

[IforB]

Taffer said:

moleamol said:

I don't think it's that simple. I await correction but I'm pretty sure you could keep fairly constant positive G in a loop depending on how it's carried out. Even though the plane is inverted at the top the G will still be positive. After all a barrel roll still inverts the aircraft, it's just that it's easier to keep the G loading positive and minimal during that particular manoeuvre.

To pull tightly enough to keep positive g throughout the whole loop you'll stall the aircraft as your airspeed decreases and angle of attack increases towards the top of the loop or just over the top. When I was taught loops, you realise why you should tighten your shoulder straps, as at the top of the loop you experience -g when pulling a symmetrical loop. The 'loops' that helicopters perform are visually messy (though still impressive!) as they cannot risk -g or the excessive +g that comes with the exit of a normal loop.

An inside loop IS a positive g manouever. Whilst the speed over the top is low and the corresponding g load might be less than one, it shouldn't negative. Normal aircraft inside loops use a 3.5 to 4 g pull on entry and exit.

Helicopters obviously perform aerobatics differently due to their limitations, but they should keep positive g throughout something as simple as a loop.

So I see no reason why something without a teetering head can't perform these manouevres when in capable hands. Mind you, as long as the g is kept positive and low, then even basic aero's are possible in a Robbie.They might not be advosable, but the ability is there.

[Quick silver]

Eric Mc said:

I assume things like rotors and rotor heads might have been based on the same technology?

However, the final production utility Blackhawk is a very different beast to the gunship of the mid 1970s.

Eh?.....assume all you like - take a look at both tail sections, all moving tail-plane (elevators) & identical tail wheel. Both marques also boast an insulated & soundproof compartment for troop transport.

The main difference between the S-67 & UH-60 (developed via S-70) is the removal of stub wings & a wider body, both to required to increase troop numbers in transpotation - something desperately required in todays theatre of operations.

Obviously a dedicated attack (non troop carrying) helicopter was also required in the shape of the Apache etc.

[dr_gn]

Quick silver said:

Eric Mc said:

I assume things like rotors and rotor heads might have been based on the same technology?

However, the final production utility Blackhawk is a very different beast to the gunship of the mid 1970s.

Eh?.....assume all you like - take a look at both tail sections, all moving tail-plane (elevators) & identical tail wheel. Both marques also boast an insulated & soundproof compartment for troop transport.

The main difference between the S-67 & UH-60 (developed via S-70) is the removal of stub wings & a wider body, both to required to increase troop numbers in transpotation - something desperately required in todays theatre of operations.

Obviously a dedicated attack (non troop carrying) helicopter was also required in the shape of the Apache etc.

I've got to assume I'm looking at the wrong images and specs w.r.t. this stuff, and if I am, I'm sorry. Call me a daft tt by all means - it won't be the first or last time, but...what on earth are you on about?

"Identical tail wheel"?

"Main differences removal of wings and a wider body"??

I'd have though small details like overall layout, totally different engines, totally different main rotor blades (including number of blades), rotor heads, totally different tail rotors, number of blades and orientations (not to mention rotor rotation directions) might constitute some pretty fking major differences.

Like I said - if I'm getting confused here - sorry.

Cheers,

[Glosphil]

Sikorsky S-52 First Helicopter Loop - 1949

http://www.youtube.com/watch?v=xhRUGKa_ImY&fea...

Claimed to be first loop by a helicopter and done at a very low altitude, and near trees at the end of the clip.

[Quick silver]

dr_gn said:

what on earth are you on about?

As previously explained, read 'S-70 ORIGINS', second paragraph : http://www.vectorsite.net/avs70_1.html