Ospreys Over Afghanistan

Military History \| How To Make War \| Wars Around the World	Rules of Use	How to Behave on an Internet Forum
Air Transportation Discussion Board
Return to Topic Page

Subject: Ospreys Over Afghanistan
SYSOP 10/26/2009 5:43:35 AM

Quote Reply

Show Only Poster Name and Title Newest to Oldest

Pages: 1 2

itfin Osprey gunship? 10/26/2009 9:50:18 PM

does anyone know why the Marines don't attempt to convert an Osprey into a gunship? It would seem to be ideal craft (vertical takeoff, flies like a plane) and Afghanistan seems the ideal place to use gunships. Just curious to see what others think of this idea.

Quote Reply

Ringo 10/26/2009 11:04:39 PM

Well, the Osprey isn't a particularly spacious vehicle. In my opinion, an Osprey gunship would just be a tiny, expensive waste of money that could be spent on REAL gunships that would be useful. It would kind of fill a niche that doesn't exist if you would.

Quote Reply

ArtyEngineer 10/26/2009 11:13:58 PM

Bottom line is you cant hang ordnance from the wings as there is only a few inches clearance betewwn the rotors and the fueselage when in aircraft mode. There was a concept demonstrator with a chin turret but it never went beyond that. The V-22 will however be recieving the BAE remote guardian weapon station which protruded from the belly but thats is purely a defensive weapon and for use in the supression of a "warm/hot" lz during insertion. The platform just doesnt suit itself to a "gunship" type role

Quote Reply

Mike From Brielle If I were 10/27/2009 10:32:37 AM

to try and create a tilt rotor gunship I'd probably try to base it on the OV-10 not the V-22. I'd keep the engines where they are and put the rotors at the wing tips of course. However I was thinking it might be possible to make it so you extend the wing out a little and keep the rotors so that they not extend any further than where the engine nacelles are. I would take the present three bladed rotor and change it to a eight bladed thin blades in two sets of four on the same axial drive shaft one set in front of the other. With the blades pointed forward for level flight the blades would be equidistantly spaced at 45 degrees. Maximum efficiency for level flight. For vertical flight the bottom set of blades would advance a bit until they were just behind the upper set of blades than they would increase their pitch until they together with the parasitic turbulence of the upper set of blades (and maybe some over the wing surface blowing action) form effectively four very large cord blades. Maximum efficiency for vertical and/or hovering. Like the old OV-10 this would allow for some area inside the engine nacelles which would allow for forward firing ordinance. I'd like allot of armor so I'd use the same engines as the Osprey if you could get them onto a airframe the size of the Bronco and you didn't overload the blade disk. Its a trade off like everything else.

Disclaimer: I am not an aeronautical engineer (I'm electrical with some background with both fixed wing and rotary aircraft) so I'm perfectly willing to admit I may be talking out of my @$$ but anyhow its just a thought.

Quote Reply

phrogdriver 11/19/2009 8:44:20 PM

No offense, but that is a completely Rube Goldberg crackpot concept. Any number of ways would get you a VSTOL armed aircraft more easily, from a compound helicopter, to VSTOL jets, to a tiltrotor. Any of those could put warheads on foreheads more easily than developing a weird new type of aircraft out of a Bronco.

Quote Reply

Mike From Brielle phrogdriver 12/16/2009 4:03:22 PM

Well don't look now but isn't the tiltrotor itself a rather Rube Goldberg concept? From what I've read on the subject and what I know about aircraft and helicopters the tilt rotors of the Osprey are a bit of a devils compromise between blades that are neither optimized for Hovering or Level Flight. As a result you get an aircraft that can't take full advantage of either its airframe or its engines. If the aformentioned concept could be proven out on a airframe such as the Bronco it could perhaps be retrofited onto the Osprey at the first major product improvement. Any aircraft that has the job of escorting the Osprey has to at least hover as well as the Osprey (that leaves out the Harrier) as well as fly in level flight as well as the Osprey (that leaves out the Cobra) . If the Bronco could hover at least as efficiently as the Osprey than it would be an ideal escort for the Osprey. The proposed new COD (Carrier Onboard Delivery) aircraft, which is about the same size as the Osprey, uses the same engines as the Osprey but has propellars that are optimized for level flight. As a consequence the new COD aircraft travels about a hundred miles an hour faster, has a higher internal cargo limit, and has more than twice the range of the Osprey. I'm not saying you could get all that performance back from the tiltrotor airframe (wing?) but it might be a big improvement. Another reason that I beleive the Bronco would be a superior experimental test bed is because of the fact you would'nt have the engines on the tips interfering with/ crowding the collective and pitch controls; IMHO they should have kept the Osprey engines in the center of the airframe above the center wing pivot point. The busyness of the Osprey wing tips were, I believe, a major factor in its initial difficulties. If NASA/ Marine Corps/ SOCOM/ Air Force could do a proof of concept demo and the concept works than maybe we could get drastic improvements in the flight performance of two airframes and get an answer to an unfilled operational requirement.

Quote Reply

phrogdriver 12/23/2009 9:51:56 PM

You're just not seeing it from an engineering and aero POV.

The nacelles are on the wingtips because it's the best place for them. If you put them midwing, then the whole wing has to swivel--a tiltwing, not a tiltrotor. This has disadvantages of its own, most notably a huge increase in AOA and drag as soon as the nacelles are brought up. If the nacelles are midwing and somehow you figure out how to make the nacelle move without the wing there are more problems. One, that's way MORE complicated than either nacelles at the tips OR a tiltwing. Two, the rotor's airflow is disrupted by the wing, causing a huge increase in power requirements.

An escort aircraft doesn't have to hover in the objective area. Employing ordnance from a hover hold is almost always a bad idea. It may have been good to popup and shoot at tanks in the Fulda Gap, but not in a knife-fight. The only requirement to hover well is for takeoffs and landings off ships or in forward areas.

The Bronco paradigm may be a decent one, but for all the Bronco-worship out there, remember its primary mission was Forward Air Control, not escort or suppression. Its main ordnance was for marking targets for other aircraft. What I think you really are getting at is an aircraft that can fly low and relatively slow to engage targets in an objective area, more like a modern A-1 Skyraider.

In anycase, starting from ancient platforms and retrofitting probably isn't going to yield a decent result. Find an aircraft with the performance you want and arm it--e.g. an attack Osprey. Or, figure out the requirements and start fresh, e.g. a VSTOL light-attack aircraft.

Quote Reply

Mike From Brielle 12/30/2009 2:50:15 PM

Perhaps I wasn?t clear

You said:

?The nacelles are on the wingtips because it's the best place for them. If you put them midwing, then the whole wing has to swivel--a tiltwing, not a tiltrotor.?

What I had already said:

?I'd keep the engines where they are and put the rotors at the wing tips of course.?

What I meant was that the swash plate and rotors and pitch change links etc, etc, etc? would be at the end of the wing while the engines would remain in the twin nacelles (or twin booms if you prefer) of the Bronco type aircraft. The engines would not contribute to the inertial mass that has to swing through 90&s30; and this would unclutter the rotor pod area and simplify maintenance I believe the clutter in the rotor pods in the Osprey was a contributing factor at Marana and if you read some of the accident reports at the other accident sites. The engines IMHO in the Osprey should be placed over the wing swivel point. The engines would be connected to the end of wing rotor pods through a drive shaft that would not only connect the rotor wing pods to their respective engines in the twin booms but serve as a link between engines and rotor pods in case you lose one engine and have to run on one engine. The drive shaft would run parallel to the main wing spar, a similar arrangement already exists in the Osprey. The drive shaft would connect the engines in the booms to the rotor pods on the wing tips.

The original Marine requirement for the Bronco was for a light attack aircraft from unimproved airfields but the Air Force chose it for a FAC (and it might have also been selected as an Air Commando attack bird at the time). Due to the flexibility of the A-4 to carry out the light attack mission the Skyhawk crowded out the Bronco from light attack mission although I understand the Marines did still use the Bronco for this purpose on occasion in addition to the FAC role. The Marines also used the Bronco as a radio relay platform, some small supply air drop and as an insertion pla

Quote Reply

phrogdriver 12/30/2009 4:35:43 PM

I'm a Marine Osprey pilot, who's been flying the V-22 for 5 years, and the CH-46E for 4 years prior to that.

I get what you're talking about, but I just am not getting how you're simplifying anything. You'd be adding transmission complexity and not getting much in return. The "busy-ness" of the nacelles is not a liaibility in inself.

What you are talking about had nothing to do with Marana. That was caused, at least according to the investigation, by vortex ring state. The mishap you're thinking of is the one that occurred north of MCAS New River. The "complexity" you are speaking of was a function of repeated re-engineering and ad-hoc fixes during development, putting hyd lines and wiring where they were hard to maintain and tended to chafe against each other. That stuff is already fixed.

You have to start at the end-state and move backwards from there, not from a fixed starting point and adapting it to your needs. In other words, you want to figure out what you need, then get the best solution. The end-state is a CAS/escort platform that has the speed and range of a V-22, while being capable of being based from an amphibioub ship or austere FOB. Hovering is just a means to an end.

The hover is not the preferred way to deliver ordnance. It's more accurate, but drastically more dangerous for the helo. The USMC rarely uses it, and the Army has started to move away from it, since they got badly hurt in Anaconda and in early stages of OIF. Really what you're looking for is the capability to move with agility down low, at relatively slow airspeeds. Even that need can be mitigated by the right sensors and weaponry, to some extent, i.e. your need is for the CAS platform to be able to spot a bad guy in a window and shoot him, as an example. Whether he can do that because he's flying at 100' or because he has a LITENING pod and can pick him out from 15000' is somewhat immaterial.

Basically, start at your requirements and work backwards to the best solution, which may be a compromise or a mixture of others. For example, the F-35 may simply provide detached escort at long ranges, while the UH/AH-1s do short-range detached escort. Eventually there might be a compound-helo modification to the UH/AH to bring their speed and range up. Actually, eventually you might see UASs take over a lot of the work, anyway.

The Bronco's a fine plane, but they did get rid of it for a reason. They can up the power and improve the sensors and it will be a sweet aircraft, but it still won't answer the question we're asking here. Making it do that would be such a reworking that you may as well start fresh, anyway.

BTW, the only way for a Bronco to deliver guys without a parachute is to land. They did do a radical jumper-deployment: pull straight up and have the parachutists fall out the back.

Quote Reply

Mike From Brielle phrogdriver 1/15/2010 4:38:17 PM

First off you are right about Marana but I believe the clutterness issue was a contributing factor in all of the other incidents. A crew chief must be able to systematically inspect all of the major elements of the drive train and its control and feeder sub-systems in turn and the clutterness would only serve as a great distraction.

All adjustable pitch rotor or propeller aircraft have transmissions of some kind. As a pilot if for some mysterious reason you don?t already know where your ransmission, swash plate and pitch change links are ask your crew chief on your next preflight, he?ll open up the cowling and show you where they are. However if your concern is in regard to the added mechanical complexity of the swash plate and pitch change links as the aircraft as described above transitions between vertical and horizontal flight then your concerns may be somewhat better founded. But I believe that the aggregate torque that comes from the drive shaft would be chiefly a geometric product of the respective AoA of the two different rotor sets they drive through the different parts of their flight regime. There would in all likelihood not be the need for an overly complex transmission. The torque / rotational velocity range may have to be somewhat broader than normal but the Osprey transmission has probably already had to account for this. There would have to be two swash plates and sets of pitch change links. Since both the top and bottom set of rotors on each pod are rotating in the same direction it would not be as complex as say counter rotating rotors. Some study would have to be directed at determining the aggregate torque in any given part of the flight regime and this unknown might be the long pole in the tent.

One of the things that I find the most disturbing in regard to your last post is your statement:

?Basically, start at your requirements and work backwards to the best solution, which may be a compromise or a mixture of others. ?

To me this statement represents one of the most egregious errors in reasoning in present day military engineering project management. This encourages the bureaucracy, politicians, contractor marketers, and the lobbyist to look to the horizon and sell as practical solution sets distant, sketchy, and unclear high risk projects as answers to practical requirements. It?s easy while looking at the horizon to miss a technical Grand Canyon between you and your objective. IMHO one only has to look at some recent high profile flop programs to see the problems with trying to look backwards from an end point where you haven?t even been to yet. Usually this entails seeing something in a civilian environment and trying to extrapolate that onto a military mission area. I have been able over the years to place civilian technology into very specific military niches but you have to be very selective in doing this by studying the environments and seeing if there is a true physical fit. Some of the recent flops have been nothing more IMHO than people trying to reverse engineer Star Trek episodes. Its much better to see where you are technically then see where you would like to go and then you can set a valid course. Then you can make valid estimates of wher

Quote Reply

1 2