Defiant first flight slips

Have we heard if the Defiant finally got the pusher prop working?

The money officially ended from the Army yesterday. That isn't to say BoSik will stop work. There are mechanisms for the Army to ask to keep the money past the end of the fiscal year (its a PITA though) and BoSik might self fund given the business importance to them...

Have we heard though?

a reply to: anzha

They have been running the propulsion system test rig for quite awhile testing different hardware modifications so they could expand the envelope. Basically wanted to know that the rig could take the increased loads at high power. They had some issues earlier in the program with part lifespans not being as long as they anticipated, so they were going to abuse it on the ground and see what happens. Was told awhile back by someone who would know that they were anticipating flights resuming in early August.

Crickets since. As far as I know, they are still at three actual flights. Either they are still putting the hours on the test rig in different configurations, or they have very quietly resumed test flights. I'd expect they would be advertising that, especially since FARA is being accelerated.

On the other hand, the second Raider airframe is definitely back in the air and testing at an aggressive rate, but that has been pretty quietly done, too. So it's hard to read the tea leaves right now.

a reply to: anzha

What was the issue with the pusher prop? That's old technology, they've been using 'em since the earliest days of powered flight...

The materials used? This is at the bleeding edge of materials science as RR pointed out a few posts and months ago.

a reply to: seagull

We don't know.

The flights flown were without the pusher prop. They stated there were transmission issues. Then...crickets.

There was a claim the army pushed them to use a new composite rotor and it delayed their flight. However, that should have been cleared with the flight as far as problems went.

However, again, flight, no pusher, and crickets.

And now...no money since the fiscal year ended.

Anything else is speculation. Fun speculation, but speculation.

It is wildly perplexing as to what happened though.

a reply to: seagull

There is (or was) definitely a material science issue. Part of it is size/weight. Those rotor discs are supporting a lot of weight. And as the size of the rotors grows, so does the weight, stress, and tip speed for the same blade rpm. These blades need to be extremely stiff because any blade sag (or rise) can result in striking a blade above or below traveling in the opposite direction. That's bad.
They seem satisfied with their solution the last time I heard.

The other issue, and one I believe is being looked at now, is that there is a lot of power being used to move heavy rotor discs (and the propulsor). Transferring that power abuses the transmission, and there were some earlier problems with lifespans for select components.

They may have run into something unexpected in ground testing as the power ramped up. They'll want to test various methods of solving the gremlins before selecting a route forward. Designing and manufacturing new parts requires quite a bit of time, as would putting hours on the test bed for the solutions.

Just guesses based on what's put there.

a reply to: anzha

There was a claim the army pushed them to use a new composite rotor and it delayed their flight. However, that should have been cleared with the flight as far as problems went.

Requirements led them to using a unique composite solution. The big thing the Army did to put them behind the eightball on the timeline was asking Sikorsky to develop from scratch a method of automation for blade production. Then they hit a snag when the tooling itself that needed to be quite long to enable laying the blades sagged a few inches under it's own weight.

Unless the had a problem with rotor-stiffness under load on the ground, that should be "solved" a long time ago. For highspeed, you would actually be unloading the rotor, so it's difficult to imagine that's the problem.

a reply to: RadioRobert

As far as I know, they are still at three actual flights. Either they are still putting the hours on the test rig in different configurations, or they have very quietly resumed test flights. I'd expect they would be advertising that, especially since FARA is being accelerated.

On the other hand, the second Raider airframe is definitely back in the air and testing at an aggressive rate, but that has been pretty quietly done, too. So it's hard to read the tea leaves right now.

Change this to "...is quietly back flying like the Raider".

www.defensenews.com...

She hadn't flown since April.

There was a nontrivial problem with the gearbox.

a reply to: anzha

breakingdefense.com...

Nontrivial is an understatement. yikes.

pusher unused. still.

I think they had that (pusher) in 2020 on the flight test schedule. And that was before the delay. So you've got several months of angst left if you're waiting on that.

Flew with prop engaged Monday.

“We have flown at least once every week in 2020,” Sikorsky test pilot Bill Fell said as he showed reporters around the aircraft.
That pace, in turn, is only possible because the Propulsion System Test Bed and other ground tests are running so hard, Fell said, that they are wringing out the risk of something failing before the aircraft ever takes off. In fact, the ground tests stress the components much more than actual flight tests, providing a margin of safety. All this means Fell & his fellow pilots can ramp up the performance faster from one flight test to the next.

linky

Ok, this thing sounds weird as hell. A lot quieter than I expected though.

twitter.com...

Sounds like an R/C plane!!!!

Seen at SPF:
military.com

Rehashes a lot of ground covered earlier, but thought this quote about the demo was interesting.

...
The Defiant hit 140 knots, while the Raider reached 180 knots...
"When we are flying at 130 knots in this machine, we are using less than 20% of the prop power and less than 30% of the engine power," said Bill Fell, senior experimental test pilot for the S-97 Raider and the Defiant.

www.flightglobal.com...

US Army selected both the Defiant and the Valor as the competitors for the FLRAA contract.

originally posted by: anzha
www.flightglobal.com...

US Army selected both the Defiant and the Valor as the competitors for the FLRAA contract.

I am completely shocked that the two competitors with flying hardware were the finalists after downselect...

$97M for BoSik.
$84M for Bell.

breakingdefense.com...