Moderators: richierich, ua900, PanAm_DC10, hOMSaR
itchief wrote:Here is a link that has video of the first flight.
Aesma wrote:A bit weird looking.
With this and the Osprey, if an engine separates (say, from an AA gun attack), can it still fly/glide, or would its equilibrium be too affected ?
mxaxai wrote:If they're smart, though, they'll have a link between the left and right rotor to avoid crashing due to a single engine failure.
mxaxai wrote:If they're smart, though, they'll have a link between the left and right rotor to avoid crashing due to a single engine failure.
Tugger wrote:itchief wrote:Here is a link that has video of the first flight.
Interesting that the blurred the view of the transmission/driveshaft sections.
Tugg
Tugger wrote:Interesting that the blurred the view of the transmission/driveshaft sections.
Tugg
zanl188 wrote:
Blurred on the ground run video as well:
https://youtu.be/dafw9bFOr1I
I'll go out on a limb here and speculate the transmission is electric & classified/proprietary as a result.
But seriously, electric transmission would have advantages for survivability and flexibility of design. No cross shaft for one.
JetBuddy wrote:I agree this thing is weird looking. It's like it's 75% engines/rotors/wings and 25% helicopter fuselage. Doesn't look efficient to me. But Bell knows better than me.
SheikhDjibouti wrote:In contrast, an AV-8B can take-off and land as a regular aircraft, if there is a 6,000ft runway available.
(Ok, I admit I'm guessing that last bit - maybe the undercarriage isn't actually stressed for those types of operations - I confess I've never seen an AV-8 land in that manner)
Ozair wrote:An AV-8 has no problem landing conventionally but I'm not sure why you made the comparison, the aircraft have very different mission sets.
SheikhDjibouti wrote:The similarities are that both types can take off and land vertically, and then transition to horizontal flight supported by wings. You are welcome to name other types that can do this too, but AFAIK it's only going to be a fairly short list. What missions they can accomplish was never part of my agenda.
The relevance of that particular similarity? I cannot believe that wasn't perfectly clear in my original post - but if you need me to repeat it.....
An AV-8 can land conventionally, which may be useful if it suffers an engine failure but can glide to a nearby runway. (However, it is possible that in all cases of engine failure, standard policy is to point the a/c out to sea and eject. I don't know.) It can also take-off from a conventional runway, and this allows a higher payload.
A V-22 Osprey suffering a (single?double?) engine failure in normal flight, cannot easily glide and land in a conventional way. If the (failed) engines are locked in normal (horizontal) flight mode, the huge diameter rotors will impact the runway long before the undercarriage reaches the tarmac. Alternatively, if after engine failure they can somehow rotate the engines (& rotors) into vertical flight mode, they avoid this scenario, but create huge drag. So for various reasons I suspect that the V-22 makes a very poor glider.
The V-280 could have the opportunity to put this right. For a start I get the impression it has a more useful wing. Secondly the engines remain horizontal, and only the driveshafts rotate out of alignment and create drag in forward (unpowered) flight. So, if for instance the undercarriage is particularly tall (like a giraffe), and the wing is mounted on a pedestal above the fuselage, maybe with significant dihedral, we might find that the rotors remain clear of the ground whilst in horizontal (normal flight) mode. This would enable conventional landings, either with or without power. However, all the pictures I have seen so far show this is not the case, and it would require re-designing. At this time I haven't seen actual rotor dimensions to know how close to possible this might be. I'm just postulating the idea.
How do you see the V-280 coping with a double engine failure? Could it auto-rotate to a safe landing like a normal helicopter? I have my doubts.
“What Bell has done is taking its historical V-22 aircraft, and all the demonstrators before that, and applies them to this next-generation tilt-rotor. It is a straight wing versus a V-22 which is not straight. This reduces complexity,” Dan Bailey, JMR TD Program Manager, said in an interview with Scout Warrior last year. “They are also building additional flapping into the rotor system and individual controls that should allow for increased low-speed maneuverability.”
SheikhDjibouti wrote:JetBuddy wrote:I agree this thing is weird looking. It's like it's 75% engines/rotors/wings and 25% helicopter fuselage. Doesn't look efficient to me. But Bell knows better than me.
50% of the traffic over my house is V-22 Osprey, so to my eyes it's quite normal.
What I would look for is a gearbox positioned as high as possible to allow the rotors to turn in forward mode without striking the ground when landing.
Either that or extra tall undercarriage like on a giraffe. A big weakness of the V-22 (IMO) is that even though it has a wing, it cannot land as a glider if it's engines fail. In fact it cannot land as a conventional aircraft with, or without engine power.
In contrast, an AV-8B can take-off and land as a regular aircraft, if there is a 6,000ft runway available.
(Ok, I admit I'm guessing that last bit - maybe the undercarriage isn't actually stressed for those types of operations - I confess I've never seen an AV-8 land in that manner)
Spacepope wrote:Although the props won't survive, the V-22 can make a normal straight ahead landing. Once.
keesje wrote:Tugger wrote:itchief wrote:Here is a link that has video of the first flight.
Interesting that the blurred the view of the transmission/driveshaft sections.
Apparently some telling views on key technology not to be shared.
dragon6172 wrote:
Not really sure what you are thinking? No direct connections between engine and transmission? Highly unlikely in my opinion.
SheikhDjibouti wrote:JetBuddy wrote:
In contrast, an AV-8B can take-off and land as a regular aircraft, if there is a 6,000ft runway available.
(Ok, I admit I'm guessing that last bit - maybe the undercarriage isn't actually stressed for those types of operations - I confess I've never seen an AV-8 land in that manner)
Kiwirob wrote:SheikhDjibouti wrote:JetBuddy wrote:In contrast, an AV-8B can take-off and land as a regular aircraft, if there is a 6,000ft runway available.
(Ok, I admit I'm guessing that last bit - maybe the undercarriage isn't actually stressed for those types of operations - I confess I've never seen an AV-8 land in that manner)
Here you go. https://www.youtube.com/watch?v=_cxATLtHZZA
SheikhDjibouti wrote:Kiwirob wrote:
I'm grateful for the response, but actually it's not what it claims. Despite the video title, when you finally get to the take-off @9:21 you can clearly see that the thrust nozzles are pointing at ~60deg down therefore this is an assisted take-off. There are also clues in terms of the amount of runway used. Likewise the landing is much slower than one might expect.
This still leaves me worrying if the tyres are stressed for normal runway speeds, or more designed as big fat shock absorbers.
Sorry.
7.3.3 Conventional Takeoff
The CTO can be used when configuration or environmental conditions preclude use of any other takeoff type (i.e.,
crosswinds or asymmetric loadings). The CTO is restricted to gross weights that will not cause the wheel/tire
limitation speed of 180 KGS to be exceeded on the takeoff roll. Refer to Performance Data, A1--AV8BB--NFM--400.
7.6.7 Conventional Landing
A standard CL, Figure 7-7, requires substantially greater distance to stop than a SL or RVL. Landing distance
available is a critical consideration when performing a CL. The brakes are designed primarily for V/STOL and are
marginal for a CL without PNB; therefore, No PNB CLs should be used only as an emergency procedure. Refer to
Performance Data, A1--AV8BB--NFM--400, for stopping distance with and without PNB.
Ozair wrote:LOL - it took a week, and plenty of going round the houses, but eventually we got there. Believe it or not, when I originally put the question, I only had vague suspicions in my head; I genuinely did not know this was the answer.SheikhDjibouti wrote:This still leaves me worrying if the (AV-8B) tyres are stressed for normal runway speeds, or more designed as big fat shock absorbers.
Have a look at the AV-8B NATOPS available here, https://info.publicintelligence.net/AV-8B-000.pdf
There is a section on conventional take off and landing which says the following,7.3.3 Conventional Takeoff; ....The CTO is restricted to gross weights that will not cause the wheel/tire limitation speed of 180 KGS to be exceeded on the takeoff roll.
7.6.7 Conventional Landing
A standard CL.... requires substantially greater distance to stop than a SL or RVL.
The brakes are designed primarily for V/STOL and are marginal for a CL without PNB; therefore, No PNB CLs should be used only as an emergency procedure.
It appears that the brakes are the issue for landing, not tyre stress, and that is why PNB is used.
itchief wrote:
bigjku wrote:itchief wrote:
I am not a huge believer in the FVL program. I think the research is important but I don’t think it will cost out well and am not sure the capabilities are necessary across the board. The UH-60 is mostly a flying truck. When you apply the engine updates to it from the ITEP program it picks up tons of capability making the bar that much higher for a presumably more expensive FVL program.
bigjku wrote:I am not a huge believer in the FVL program. I think the research is important but I don’t think it will cost out well and am not sure the capabilities are necessary across the board. The UH-60 is mostly a flying truck. When you apply the engine updates to it from the ITEP program it picks up tons of capability making the bar that much higher for a presumably more expensive FVL program.
Bell Helicopter, a subsidiary of Textron Inc., announced that its V-280 Valor tiltrotor aircraft performed its maiden flight with the landing gears retracted.
“Continuing the pace after recent demonstration flights, the V-280 raised its gear entering another phase of envelope expansion and validation of key performance parameters”, the company said in a statement.
The aircraft had conducted its maiden flight on Dec. 18 last year while the first cruise mode flight was performed on May 11 this year. During the “cruise mode,” the rotors pivot, in flight, from vertical lift mode to fully forward facing.
V-280 Valor is a third-generation tilt-rotor aircraft being developed by Bell Helicopter and Lockheed Martin for the U.S. Army’s Future Vertical Lift (FVL) program.
The Bell V-280 Valor program is part of the Joint Multi Role Technology Demonstrator (JMR-TD) initiative. The JMR-TD program is the science and technology precursor to the Department of Defense’s Future Vertical Lift (FVL) program.
The Team Valor includes Bell Helicopter, Lockheed Martin, GE, Moog, IAI, TRU Simulation & Training, Astronics, Eaton, GKN Aerospace, Lord, Meggitt and Spirit AeroSystems. GE Aviation will manufacture the engines for the V-280, with the prototype (air vehicle concept demonstrator, or AVCD) using the General Electric T64.
In one major difference from the earlier V-22 Osprey tiltrotor, the engines remain in place while the rotors and drive shafts tilt. A driveshaft runs through the straight wing, allowing both prop rotors to be driven by a single engine in the event of an engine loss. The fuselage is visually similar to that of the Sikorsky UH-60 Black Hawk medium lift helicopter.
The V-280 has a retractable landing gear, a triple-redundant fly by wire (FBW) control system, and a V-tail configuration. The wings are made of a single section of carbon-fiber-reinforced polymer composite, reducing weight and production costs.
The V-280 is reportedly capable of a cruising speed of 280 knots (320 mph; 520 km/h) (hence the name V-280), a top speed of 300 knots (350 mph; 560 km/h), a range of 2,100 nautical miles (2,400 mi; 3,900 km), and an effective combat range of 500 to 800 nmi (580 to 920 mi; 930 to 1,480 km).
Expected maximum takeoff weight is around 30,000 lb. The V-280 will have a crew of 4 and be capable of transporting up to 14 troops. Dual cargo hooks will give it a lift capacity to carry a 10,000 lb (4,500 kg) M777A2 Howitzer while flying at a speed of 150 knots (170 mph; 280 km/h).
trpmb6 wrote:Unpopular opinion of the day... The v280 isn't the prettiest of birds out there.
aumaverick wrote:trpmb6 wrote:Unpopular opinion of the day... The v280 isn't the prettiest of birds out there.
Is it the large and ungainly V tail that throws off the proportions? The engines and nacelles aren't too distracting.
trpmb6 wrote:aumaverick wrote:trpmb6 wrote:Unpopular opinion of the day... The v280 isn't the prettiest of birds out there.
Is it the large and ungainly V tail that throws off the proportions? The engines and nacelles aren't too distracting.
I think it's just the proportions. The engines (read propellers/rotors) are so unwieldy compared to the comparatively small tail and fuselage. And the fuselage isn't even really small as far as helicopters go. It's just the engines are THAT big!
Don't get me wrong, I love the valor. It's just that red-headed step-child type of love.
estorilm wrote:I bet a really long telephoto shot with slow shutter speed for the big blades from the front looks pretty mean though.
trpmb6 wrote:estorilm wrote:I bet a really long telephoto shot with slow shutter speed for the big blades from the front looks pretty mean though.
This is an Osprey, (and poor quality) but gives you an idea hehe
trpmb6 wrote:Does anyone know if the Valor can taxi? I assume it might be able to pitch the rotors fwd enough to get some fwd movement, but it'd be incredibly inefficient.
WIederling wrote:trpmb6 wrote:Does anyone know if the Valor can taxi? I assume it might be able to pitch the rotors fwd enough to get some fwd movement, but it'd be incredibly inefficient.
IMU these ships have full cyclic blade control. You don't need to tilt for directional flight.
you need to tilt for _high speed_ forward flight.
Noshow wrote:If these birds can be made reliable enough, and that is just a matter of time and money, I can see some big future in commercial aviation. Imagine city center to far away hub airport or right away to the next city center. Tiltrotors are truly fascinating. More like all those electric manned toy drones together.