LHX Program

[Stargazer]

Thanks for your speedy answer, Greg.

Getting together to buy someone a present is one thing, but this is different.

If the deal was to collectively purchase something that ends up in a museum collection, that would be a whole different thing!

However, I can see no justification to collectively purchase something that ends up in a privately-owned collection. We all contribute in various degrees to the forum... Where to draw the line between those who "deserve" a present and those who don't? You mention Mark, who gives generously a lot of his time and energy to this forum, but you also mention Scott, who puts conditions and a pricetag on his research at upship.com. Each has his valid reasons to do or not do what he does, but I think that if the forum is to reward them for their efforts, it should be by means of a donation, as has been done before.

There are hundreds of wonderful documents for sale on eBay, many much more valuable or historically worthwhile than these LHX images. Making it possible for all that material to end up in a place where they can benefit the community would be great. But I will NOT participate in a group buy that benefits one single member in the end. Not because I deem them unworthy; simply because at the end of the day, we have NO guarantees that whatever we collect individually will survive us. Our kids may decide one day to dump all our aviation stuff, our widows may sell it on a jumble sale, and even in our lifetime our basement might get flooded, our attics may take fire and so forth.

 

[Orionblamblam]

Getting together to buy someone a present is one thing, but this is different.

Who said anything about a "present?" Take these Bell prints, for instance: if there was a "group buy," it would seem logical that everyone who bought in would get high-rez scans of the images. Thus everyone has what everyone else has. One person would of course end up with the physical objects, but in this case... who cares? Conceptual art, like music, is just a series of ones and zeroes. Once you have a full-color high-rez and complete scan, the physical print is not some magically superior thing.

Of course, agreements could also be reached regarding dispersing the physical objects. In a case like this, the individual prints could be scattered around. Or if ten people paid ten buck and one person paid fifty, everybody gets scans except for the guy who paid more, who gets scans and prints.

 

[overscan (PaulMM)]

Actually, in the only previous example of a group buy funded from forum donations, Mark Nankivil purchased the items, and was repaid from the forum donations, and then - with his own money - paid to ship them to me, unprompted. He had confirmed that none of the items were needed for the Vought Heritage archives -they already had copies.

So I have the items (the Vought concept prints) in a folder at my house. I spent a couple of hours scanning and editing them and posted those scans. I actually have a new, better scanner, and may give it a go on them to see if I can get better results.

As regards the Bell concept art, I would happily contribute towards Mark buying them if Mark is going to keep them. He's already shared some awesome LHX brochures with us.

Scott has, several times, purchased an item with his *own* money and scanned it and then distributed the scans among a bunch of people who paid money for the privelege. Thats entirely his own business and, other than a method of contacting potential contributors, nothing to do with this forum.

 

[Mark Nankivil]

Hi All -

I bought a book of Bob Cunningham artwork from this seller earlier this year and just bought a glider book he had posted as well. I'll make an offer for the whole lot (say $60) and see if he'll accept. If so, will let you know the results and we can figure out a way for everyone to end up with a high rez set of scans for a nominal fee or a direct donation to support SPF.

Enjoy the Day! Mark

 

[overscan (PaulMM)]

No worries Mark. I did try contacting him without response, but as a previous customer you may have better luck.

 

[Mark Nankivil]

Just got word they're mine. I'll wait until they are actually in hand but would expect that will be quick. Once I have them, I'll post some info on how to receive full rez (300dpi) scans.

Enjoy the Day! Mark

 

[overscan (PaulMM)]

These were purchased on Ebay by Mark Nankivil and scanned to support the forum. High resolution (300 dpi) copies will been made available to all donators in a few hours.

 

[overscan (PaulMM)]

These were purchased on Ebay by Mark Nankivil and scanned to support the forum. High resolution (300 dpi) copies will been made available to all donators in a few hours.

Emails have been sent. A few have bounced, so get in touch if you've donated but haven't got the email.

 

[Stargazer]

Absolutely splendid. I'm perfectly content with these 72 dpi rez versions! Thanks to all the donators and to Paul for sharing them with all of us non-donators.

 

[Sundog]

Thanks Mark and Paul.

 

[fightingirish]

Many Thanks to Mark and Paul!!!

 

[hesham]

Hi,


here is two drawings to McDonnell Douglas LHX and SCAT helicopter with
NOTAR,from;


http://www.dtic.mil/dtic/tr/fulltext/u2/a227196.pdf


and my dear Stingray site;
http://stingraysrotorforum.activeboard.com/t36859305/mcdonnell-mcdonnell-douglas/

 

[yasotay]

I found these pictures (sorry for the quality) of an early model of the Sikorsky original SCAT concept using early co-axial rotor and thruster that is now used in their X2 technology.

 

[Triton]

Thank you for sharing, yasotay.

 

[Stargazer]

Very nice. Wish we could see what's written on the plate affixed to the stand. It seems to be the acronym of the program, ending with "X"...

 

[hesham]

Great find my dear Yasotay.

 

[yasotay]

Very nice. Wish we could see what's written on the plate affixed to the stand. It seems to be the acronym of the program, ending with "X"...

The stand says "LHX"

 

[Stargazer]

Very nice. Wish we could see what's written on the plate affixed to the stand. It seems to be the acronym of the program, ending with "X"...

The stand says "LHX"

Oh, okay... I didn't realize Sikorsky had submitted a tail ring configuration to the LHX tender.

 

[Triton]

It appears that Sikorsky has studied compound rotorcraft with the Advancing Blade Concept (ABC) and a pusher propeller for decades before repackaging it as X2 Technology. Did the vibration issue cause them to abandon this configuration for LHX or was it considered too risky?

 

[Jemiba]

From http://www.aviastar.org/helicopters_eng/sik_s-69.php

"[font=verdana, arial]This approach was seen as a possible solution to the Army's search for a new light attack helicopter (LHX), and further funding was recommended. The S-69/XH-59 programme was abandoned, however, and the need for LHX was only answered in the 1990s with the selection of the RAH-66 Commanche. "[/font]
Vibration issues aren't only a problem for helis with ABC or co-axial rotors, although interaction between the upper and lower
rotor probably will add problems. But a conventional rotor at high speed with the retreating blade stalling isn't much better,
I think

 

[yasotay]

It appears that Sikorsky has studied compound rotorcraft with the Advancing Blade Concept (ABC) and a pusher propeller for decades before repackaging it as X2 Technology. Did the vibration issue cause them to abandon this configuration for LHX or was it considered too risky?

It is hard to say how much the technological challenges caused Sikorsky to turn away from the compound rotorcraft effort, or if the decision was made by the (then) Secretary of the Army's announcement that the LHX should be a conventional helicopter in order to reduce risk to the program.

 

[Triton]

Includes footage of the Sikorsky S-75 ACAP, fly-by-light, and Sikorsky S-76 SHADOW (Sikorsky Helicopter Advance Demonstrator of Operator Workload).

http://youtu.be/fTuDT6pP4BU

 

[F-14D]

It appears that Sikorsky has studied compound rotorcraft with the Advancing Blade Concept (ABC) and a pusher propeller for decades before repackaging it as X2 Technology. Did the vibration issue cause them to abandon this configuration for LHX or was it considered too risky?

It is hard to say how much the technological challenges caused Sikorsky to turn away from the compound rotorcraft effort, or if the decision was made by the (then) Secretary of the Army's announcement that the LHX should be a conventional helicopter in order to reduce risk to the program.

True; it's probably a combination of both. When the Army "dumbed down" LHX, there was no point in producing a faster, more capable (and expensive) vehicle when the requirements document said you'd get no credit for the extra performance. That, and Sikorsky realized that the technology wasn't there yet. They'd be happy to keep developing it as long as someone else was paying, but they knew they wouldn't be able to mount a credible bid with it in a competition.

 

[Triton]

So that eliminated Advancing Blade Concept (ABC) and Bell Advanced Tiltrotor (BAT) from the LHX program. No point in developing extra features that the customer is not willing to pay for.

 

[Orionblamblam]

An ad in Av Week back in the day:

 

[F-14D]

So that eliminated Advancing Blade Concept (ABC) and Bell Advanced Tiltrotor (BAT) from the LHX program. No point in developing extra features that the customer is not willing to pay for.

Even if they hadn't dumbed it down, ABC as it stood at the time wouldn't have had a chance. The data derived from the XH-59 program showed that it wasn't ready for prime time. One intriguing possibility if the Army had stayed with its original goals might have been that Bell and Boeing would merge their separate LHX Tilt-Rotor designs and bid as a team. If they did it's possible no one else would have bid. Even back then, competition was becoming not so much a means to an end as an end in itself, so the bureaucracy wouldn't like that.

Besides, such a vehicle would look and perform too much like an airplane and maybe Army didn't want to take on USAF again, who would try and kill the program.

 

[sferrin]

It's too bad Sikorsky couldn't get the X-Wing concept to work. Thought it was interesting.

 

[yasotay]

It's too bad Sikorsky couldn't get the X-Wing concept to work. Thought it was interesting.

Agreed. But who knows! With 3d printing and improved metallurgy it may again be feasible to consider. I think the greatest challenge will be making it economically viable. What are the maintenance requirements for the rotor system?

 

[F-14D]

It's too bad Sikorsky couldn't get the X-Wing concept to work. Thought it was interesting.

Agreed. But who knows! With 3d printing and improved metallurgy it may again be feasible to consider. I think the greatest challenge will be making it economically viable. What are the maintenance requirements for the rotor system?

The problem with X-Wing was not with metallurgy, construction or the like. The problem was it was a wildly complex and expensive concept with little practical use even if it did work.

To wit: When in powered lift mode, lift and control was provided by air pumped aft over the rotating blades. Fine. In wingborne mode, the leading edge when flying with them acting as wings. So, the air has to now be diverted to the other side so those blades can now function as wings. Pretty complex already, huh? Now consider what would be going on in transition, either way, where you'd have to rapidly be changing betwen leading and trialing edge blowing at a constantly varying rate. Then consider keeping those little ducts clean and clear, and how to compensate if some don't flow as well as others, a situation that may be changing throughout the flight. It's the reason that engineers working on it proudly proclaimed it would require a flight control system an order of magnitude more complex than the Space Shuttle. It's also why the Circulation Control Rotor testbed only hovered

It became apparent that unless you were wiling to significantly overpower the system, thereby killing efficiency, an X-Wing would not be bale to maintain level flight during conversion, a notable inconvenience at low level. Oh, yeah...it would have had the autorotational/gliding characteristics of a brick. This is just the nature of the concept. Auxiliary lifting surfaces or external propulsion units were also considered, but that kind of defeated the purpose of having the X=Wing in the first place. It was also posited that for viability a new kind of convertible engine would need to be developed.

Plus, Sikorsky itself acknowledged that while an operational X-Wing would have a higher dash speed, its cruise speed would be slower than that of Tilt-Rotor. Again, nature of the concept not of construction or material technology.

I think it was one of those cases that the engineers got so wrapped up in in the adventure of the concept that they lost sight of the practicality. Sort of like me producing a process that can turn a pound of lead into $5,000 worth of gold. Only problem is my process requires $10,000 worth of chemicals an reactants each time I do it.

 

[AeroFranz]

I remember seeing a cutaway of the proposed rotor head showing all the ducting required. It might have been for the RSRA testbed. it was NASTY...

 

[jsport]

It's too bad Sikorsky couldn't get the X-Wing concept to work. Thought it was interesting.

Agreed. But who knows! With 3d printing and improved metallurgy it may again be feasible to consider. I think the greatest challenge will be making it economically viable. What are the maintenance requirements for the rotor system?

The problem with X-Wing was not with metallurgy, construction or the like. The problem was it was a wildly complex and expensive concept with little practical use even if it did work.

To wit: When in powered lift mode, lift and control was provided by air pumped aft over the rotating blades. Fine. In wingborne mode, the leading edge when flying with them acting as wings. So, the air has to now be diverted to the other side so those blades can now function as wings. Pretty complex already, huh? Now consider what would be going on in transition, either way, where you'd have to rapidly be changing betwen leading and trialing edge blowing at a constantly varying rate. Then consider keeping those little ducts clean and clear, and how to compensate if some don't flow as well as others, a situation that may be changing throughout the flight. It's the reason that engineers working on it proudly proclaimed it would require a flight control system an order of magnitude more complex than the Space Shuttle. It's also why the Circulation Control Rotor testbed only hovered

It became apparent that unless you were wiling to significantly overpower the system, thereby killing efficiency, an X-Wing would not be bale to maintain level flight during conversion, a notable inconvenience at low level. Oh, yeah...it would have had the autorotational/gliding characteristics of a brick. This is just the nature of the concept. Auxiliary lifting surfaces or external propulsion units were also considered, but that kind of defeated the purpose of having the X=Wing in the first place. It was also posited that for viability a new kind of convertible engine would need to be developed.

Plus, Sikorsky itself acknowledged that while an operational X-Wing would have a higher dash speed, its cruise speed would be slower than that of Tilt-Rotor. Again, nature of the concept not of construction or material technology.

I think it was one of those cases that the engineers got so wrapped up in in the adventure of the concept that they lost sight of the practicality. Sort of like me producing a process that can turn a pound of lead into $5,000 worth of gold. Only problem is my process requires $10,000 worth of chemicals an reactants each time I do it.

WOW, thank you for finally explaining what many surely had not heard properly explained.. a Christmas present for geeks. (not being sarcastic)
Surely you don't believe tilt-rotor is the end of helicopter like VTOL technology? There is a pic on Secret projects appearing to show Chinese concept for counter rotating CRW for instance.

"an X-Wing would not be bale to maintain level flight during conversion, a notable inconvenience at low level." such understatement was a great holiday hoot.

 

[overscan (PaulMM)]

Better copy of this image

Source: Stealth Warplanes, Doug Richardson, 1989

 

[yasotay]

A co-worker walked in this morning with some pictures and says "Remember this?"
Did not see these anywhere else on the Forum so hope you enjoy.
Co-worker is much older by the way B)

 

[AeroFranz]

An all-time favorite ... Thanks!

 

[hesham]

Very nice pictures my dear Yasotay.

 

[Stargazer]

Nice pics of the BAT, thanks!!

 

[hesham]

Hi,


http://halfdome.arc.nasa.gov/FINAL_Harris%20Vol%20II_Feb%2011%202013.pdf

 

[BAROBA]

Anyone seen this?
It seems to be related to LHX? It is part of the Boeing Sikorsky submission or a seperate Sikorsky submission?


http://www.benl.ebay.be/itm/6-1985-PUB-SIKORSKY-AIRCRAFT-US-ARMY-LHX-PROTOTYPE-HELICOPTER-ORIGINAL-ADVERT-/300862844932?pt=JG_FR_Collections_Aviation&hash=item460cd2b004

Cheers,

Rob

 

[TomS]

That's the S-76 SHADOW testbed. It was related to LHX, testing fly-by-wire controls and ways to manage workload in one-man cockpits.

http://www.kamov.net/general-aviation/s-76-shadow/

 

[Firebee]

Here are some nice photos of the S-76 Shadow in flight and an interior photo. I found these at http://aviadejavu.ru/Site/Crafts/Craft29876.htm


There is a nice painting which I can't seem to find online of the Shadow in the book "Illustrated Guide to Future Fighters and Combat Aircraft" by Bill Gunston. (ISBN 0688060654)