Bell/Lockheed and Sikorsky/Boeing Selected for JMR-TD
I would suggest Bell-Boeing have no bragging rights to on-time delivery of Tilt Rotors.
What matters is how long the Customer is willing to wait and what priority it places on timely delivery of the machines..
What matters is how long the Customer is willing to wait and what priority it places on timely delivery of the machines..
Keeping Promises and Full Transparency
While I respect and admire the engineering and manufacturing team work working on the SB-1, the top executives at both Sikorsky and Boeing have conducted themselves poorly.
The facts are as follows;
Sikorsky/Lockheed and Boeing are the two largest defense contractors in the world. Bell/Textron is ranked about number 11 in the US.
The combined man power and financial assets of Sikorsky/Lockheed and Boeing are an order of magnitude greater than Bell/Textron.
Bell prior to FVL contract signing requested approximately eight additional months to achieve first flight. The extension was rejected based on Sikorsky and Boeing’s promises that they could meet the contract date of first flight in fall of 2017.
While the SB-1 rotor blades have been highlighted as the cause of the program delays, it does not take great effort to realize that based on late design reviews and delivery of major assemblies the entire program has been running a year behind schedule.
Bell has been transparent with the V-280 progress throughout the program. The SB-1 has been shrouded in secrecy except for when missing a milestone become obvious to the public.
Which aircraft is best still needs to be determined. But as far as keeping promises and transparency, Bell deserves to brag.
The facts are as follows;
Sikorsky/Lockheed and Boeing are the two largest defense contractors in the world. Bell/Textron is ranked about number 11 in the US.
The combined man power and financial assets of Sikorsky/Lockheed and Boeing are an order of magnitude greater than Bell/Textron.
Bell prior to FVL contract signing requested approximately eight additional months to achieve first flight. The extension was rejected based on Sikorsky and Boeing’s promises that they could meet the contract date of first flight in fall of 2017.
While the SB-1 rotor blades have been highlighted as the cause of the program delays, it does not take great effort to realize that based on late design reviews and delivery of major assemblies the entire program has been running a year behind schedule.
Bell has been transparent with the V-280 progress throughout the program. The SB-1 has been shrouded in secrecy except for when missing a milestone become obvious to the public.
Which aircraft is best still needs to be determined. But as far as keeping promises and transparency, Bell deserves to brag.
This is actually a pretty salient point, as Boeing themselves said that the iron bird has only been run twice to date which means without blades. If the blades truly are all they were waiting on, its hard to imagine that completed machine just sitting idle for 12 months.
My experience with automated fiber placement is such that I would not recommend it for a one off aircraft. Rather, design the blade so that it can be automated, but hand make the demonstrator. The 429 construction techniques work well for a conventional helicopter blade, but perhaps aren’t as appropriate for a thick, torsionally stiff tiltrotor blade.
In any case, I would never have suggested SB>1 use AFP for a demonstrator blade. I suspect that wasn’t the only delay, but I know the struggles the team would need to overcome to AFP a long blade spar like the article implies.
Hope we see more information soon. Will be interesting to see if the flight vehicle matches the renders we’ve been seeing for years.
In any case, I would never have suggested SB>1 use AFP for a demonstrator blade. I suspect that wasn’t the only delay, but I know the struggles the team would need to overcome to AFP a long blade spar like the article implies.
Hope we see more information soon. Will be interesting to see if the flight vehicle matches the renders we’ve been seeing for years.
Apparently SB-1 is now "complete" minus blades! If that truly is the case, I cant understand why the media reporting on this hasn't leaned on Boeing to release some pictures. Bell basically gave the media a build log from the earliest stages, yet the aviation press seems content to show the same CG renderings of Defiant over and over for 3 years. You would think they would at least get Boeing on record explaining why they want to keep it under wraps when their competition is flying almost daily.
The blade fabrication issue seems especially interesting, as I understand that Bell specifically went away from Automated Fiber Placement and toward broadgoods on V280 due to their experience on 429 and 609 fiber placed production blades. Must have been interesting to the Army to be briefed by one competitor that a specific manufacturing technology was less desirable, while the other was struggling for years behind closed doors (supposedly delaying the whole program) trying to make it work.
https://www.rotorandwing.com/2018/10...t-main-rotors/
The blade fabrication issue seems especially interesting, as I understand that Bell specifically went away from Automated Fiber Placement and toward broadgoods on V280 due to their experience on 429 and 609 fiber placed production blades. Must have been interesting to the Army to be briefed by one competitor that a specific manufacturing technology was less desirable, while the other was struggling for years behind closed doors (supposedly delaying the whole program) trying to make it work.
https://www.rotorandwing.com/2018/10...t-main-rotors/
Based on literally the only photo Boeing (probably inadvertently) released to date, I think the fuselage shape is what they have been showing in the newer CG videos starting from mid 2017.
Since SB1 uses AFP, then that likely means all unidirectional tape material. One thing to consider is the damage tolerance capability of a high strain, ultra-stiff rotor blade constructed entirely of high modulus or UHM carbon tape. Even with modern toughened resin systems, it would be very interesting to see failure modes from typical ballistic threats or bird strikes
Since SB1 uses AFP, then that likely means all unidirectional tape material. One thing to consider is the damage tolerance capability of a high strain, ultra-stiff rotor blade constructed entirely of high modulus or UHM carbon tape. Even with modern toughened resin systems, it would be very interesting to see failure modes from typical ballistic threats or bird strikes
Last edited by SansAnhedral; 11th Oct 2018 at 17:47.
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HI
At the very start of my Career I worked at Westlands at Yeovil on composites development.
We built a prototype tailboom for the scout from all Unidirectional High Modulus Carbon fibre ( there was not any woven product available in the mid 70's).
I witnessed the destructive test and I will never forget the load crack when it failed , to call it an explosive failure was an understatement.There were bits of tailboom all over the hangar. If I am not mistaken it exceeded design load by quite a factor .
I would suspect that the machine laid tape would be interleaved with woven fabric on any new blade , especially at the root .
Neil
At the very start of my Career I worked at Westlands at Yeovil on composites development.
We built a prototype tailboom for the scout from all Unidirectional High Modulus Carbon fibre ( there was not any woven product available in the mid 70's).
I witnessed the destructive test and I will never forget the load crack when it failed , to call it an explosive failure was an understatement.There were bits of tailboom all over the hangar. If I am not mistaken it exceeded design load by quite a factor .
I would suspect that the machine laid tape would be interleaved with woven fabric on any new blade , especially at the root .
Neil
HI
At the very start of my Career I worked at Westlands at Yeovil on composites development.
We built a prototype tailboom for the scout from all Unidirectional High Modulus Carbon fibre ( there was not any woven product available in the mid 70's).
I witnessed the destructive test and I will never forget the load crack when it failed , to call it an explosive failure was an understatement.There were bits of tailboom all over the hangar. If I am not mistaken it exceeded design load by quite a factor .
I would suspect that the machine laid tape would be interleaved with woven fabric on any new blade , especially at the root .
Neil
At the very start of my Career I worked at Westlands at Yeovil on composites development.
We built a prototype tailboom for the scout from all Unidirectional High Modulus Carbon fibre ( there was not any woven product available in the mid 70's).
I witnessed the destructive test and I will never forget the load crack when it failed , to call it an explosive failure was an understatement.There were bits of tailboom all over the hangar. If I am not mistaken it exceeded design load by quite a factor .
I would suspect that the machine laid tape would be interleaved with woven fabric on any new blade , especially at the root .
Neil
There is off-axis-laid tape in the design of the similar but smaller S-97 and X2 blades to create the required torsional stiffness, for example, but it is all still unidirectional tape with no fabric.
If you were using AFP to fabricate a SB1 blade, then the addition of broadgood fabric plies would negate the advantages of using an automated tape laying system as you would have to repeatedly stop the process. I imagine the additional bulk of fabric with the weft fibers could also cause overall weight challenges, since the warp direction is inherently softer from being woven and would require more plies to achieve the same stiffness.
Based on the patent applications for V280 blades, they appear to be made entirely of fabric material, though the design requirements of a proprotor are entirely different. Hopefully the SB1 blade patent shows up soon so we can see whats going on inside!
The end of 2018is rapidly approaching. Just 31 calendar days or 15 regular work days. Any rumours on the Defiant’s First Flight status?
Last edited by CTR; 1st Dec 2018 at 13:59. Reason: Inserted 2019 instead of 2018
It’s Official
SB announces no flight of SB-1 until sometime in 2019 due to design problems.
https://www.flightglobal.com/news/ar...elayed-454362/
https://www.flightglobal.com/news/ar...elayed-454362/
“This year we fly three airplanes that are super relevant to Future Vertical Lift,” said Chris Van Buiten, Sikorsky’s VP for innovation, “so we congratulate the other guys on flying their one airplane.”
So, first flight December 45th then. Sikorsky standard work!
Not much of a Christmas break
Sadly, a lot of hard working Sikorsky Engineers will not be spending much time with family this Christmas break. Had the Defiant gotten air under the wheels before Christmas they would have enjoyed a well earned rest.
Today, December 18th marks one year of Bell V280 Flight Testing. Bell just released this video to celebrate this milestone. Link to video below.https://m.youtube.com/watch?feature=...&v=p4w_17lZI0c
SB>1 photo, no hub fairings
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Look at the tailwheel housing (dorsal fin??)and the rear pusher prop proximity to the ground, wow. With my untrained eye any nose high attitude on touchdown (running landing, off level landing) and there's gonna be a nasty surprise for the crew up front. But damn, what a sexy looking beast !
Look at the tailwheel housing (dorsal fin??)and the rear pusher prop proximity to the ground, wow. With my untrained eye any nose high attitude on touchdown (running landing, off level landing) and there's gonna be a nasty surprise for the crew up front. But damn, what a sexy looking beast !
The landing gear look real enough to me, but they clearly don't have the complex articulation of a AW609 or S-97... having a wide fuselage makes the gear simpler.
There isn't a need for significant cyclic flare, nose up landings in an X-2 type aircraft. Pilots can command a level body descent and deceleration using reverse thrust on the prop... and what a prop on the rear of this thing!
