Hot Hot Hot (V-22 melting decks)

AW ST

US Navy amphibious ships operating MV-22B Osprey tilt-rotors will need major structural repairs after less than half their planned service lives, according to a newly released Navy document, unless a new Deck Thermal Management System (DTMS) can be developed to protect the decks from exhaust heat.

The JSF presents a slightly different problem. Its exhaust is hotter and faster, but in normal operations will not be directed at the deck for more than two minutes. Nevertheless, the Navy expects "a severe thermo-mechanical impact" on ship decks, no doubt an immense surprise: who could possibly have thought that an 18000-pound-thrust nozzle, blasting straight down at the deck at a distance measured in inches, might be a problem?

you shove more power out of the back end , then make it point downwards at a steel deck , then laws of physics come into play here - and they didnt actually consider this ??

[edit on 19/11/09 by Harlequin]

The Osprey has had a plague of problems since it's conception and realization. Are they starting to land these behemoths on the decks of air craft carriers now?

It begs to question why they are still using this platform after all the troubles it's endured. I bet some high-power politician has a lot of money wrapped up in this program. Which would explain the overlooking of it's problems again and again.

reply to post by susp3kt


dept.kent.edu...


yup they allready land on carriers - hence why they know theres a problem (and will be with the white elephant called the F35)

used to have the same problem with the Harriers on the Tarawa class amphibious assault ships... they simply installed blast deflectors... why not do the same here? Or maybe better yet is not spool with the props in tilt position until ready to launch???

Hmmm....

Although this does not surprise me when it comes to engineers, (sorry had to say it and no offense intended to anybody), it does actually surprise me!
Curious as to what the AV 8B does to the deck?

We had them in our squadron but as we were land based, we had no interaction with this scenario. There are many many plans with the F 35 that have not been made public yet, although it may be considered a "white elephant", I fully expect that it will be a platform that will become operational in a multitude of variants at any cost.

This is a great post so far though, if anybody has more links to this...Please post them. Honestly I have some doubts that this is a problem that could be overlooked, but then again it usually is this most simple of things that throws a wrench in the works.

Peace,
Mondo

Not a big deal. imo
there needs to be developed a deck coating.
maybe ceramic that will not pass the heat to the deck. or at the very least lessen the effect of the engine on the deck.

and if not the whole deck. maybe just part of it. like the helipad.

I don't consider the criticism justified. The platform was built long before the jet. the engineers designing the jet are aerospace engineers, not civil engineers. Or whomever builds a flight deck.

Quite frankly, I wouldn't consider a few seconds to be enough to do damage.

Actually just a few seconds can do quite a bit in most situations, but with the tolerances that are built into the decks and such, it surprises me as well. You make a good point above with the differences in developmental age so yeah, it would make sense that something like a ceramic coating or a similar heat withstanding substance may be able to be added.
As I mentioned before, whatever the case is, this will be a temporary setback only in my opinion.

Peace,
Mondo

reply to post by Mondogiwa


Sorry I should clarify. I wouldn't EXPECT a few seconds to do damage.

Now, I have never seen a flight deck so I am just asking this question. If it is not a new carrier, could age and frequent use and degredation of the deck be considered as well?

reply to post by Mondogiwa


Just a heads up I did a quick search on specs for the LHA-6 America...

The LHA replacement modifies the LHD design to maximize support for the V-22, the CH-53, and the F-35 Joint Strike Fighter, with adequate service margins for growth. The biggest change brought about in the Global War on Terror is LHA(R). The aviation specific variant of the LHA(R) has no well deck, a monumental decision that denotes a cultural change. The Marines were seen as bringing the ACE (Aviation Coordination Element) increasingly back to sea.

Couldn't find anything that specifically addresses the heat problem but as this new ship is being designed just for these aircraft you'd think they have some fix in the works...
Ship specs

the best i could find is that exhaust temperature is around 1700 degree`s C , an oxy-acetalyne torch is 3200C - and that cuts through steel like a hot knife in butter.

Nice find with the link, and yeah you are exactly right with those temps. New tech is going to be coming online to deal with the issues no doubt, just a bit of a yo yo game as always it seems.

Believe it or not, carrier decks can be tempered in a way over longer exposure, but this is not to say that an very direct application of 1700 plus degree temperature cannot liquify it. Great finds again with the links gang...thanks.

Peace, back to check it out soon!
Mondo

There is a very simple solution to all of this. Tilt the rotors about 8 degrees forward. As the entire engine rotates with the rotor, this should reduce the amount of blast that is focused on the deck. The only reason that I can see for them not doing this is the rotors would become a safety hazard for someone in the wrong place.

[edit on 19-11-2009 by JIMC5499]

As far as the V 22 that may work, I have never even seen one in person and have no real basis for interpretation on it. As far as the physics of it goes that makes sense in most circumstances if the deck is clear in all direction far quite a distance in case the roll exceeds the expectation and it takes out numerous Rhinos and the like. I get what you mean but it sounds precarious at best due to the limitation of room and vast congestion on deck..again, just due to previous encounters of mine.
But, maybe things are different now and the deck and aircraft allow for that??

The real temperature issue comes more into play with the F 35 I think. With the AV 8B, you have four nozzles and a much smaller thrust that is diversified into those four nozzles/exhaust outlets. The F 35 magnifies this of course with all exhaust performance put into a massive acute engine outlet at one moment....whole different scenario.

Let's hope that dech improvements are in the works or online already right!?

Other thoughts/info???

Peace,
Mondo

reply to post by Mondogiwa


In a film I watched on the development of the f 35 they don't redirect the jet blast... rather they use a drive shaft to turn a fan mounted just behind the cockpit... They didn't really explain how that worked but that fan didn't look like a jet engine yet they still talked about the problems of hot gases bouncing up and choking the main engine... A problem all to common to the AV 8B... said film was on the contest for the contract to build the joint force fighter PBS

DaddyBare,

Interesting, I will have to contact a friend and do some searching to get some more info on this topic, thanks!

I know that the AV 8B suffers from a limited time of loiter in any hover position due to a heat build up and that the F 35 has as one of its design intentions to extend this a great deal. It will be interesting to see if this is a possibility in production...when that happens!? The fan that you are speaking of does do exactly what you explained, but then again there are inherent problems with any system like this where the cooling capability does have its limits, now add to that weapons stores, fuel, etc...and we have exponential stresses.

I will try to check out some things and get back later.

Peace,
Mondo

[edit on 19-11-2009 by Mondogiwa]

there are 2 lift devices on the F35 - a cold air shaft driven fan behind the cockpit and the main engine swivels to point downwards.





X35 but near enough the same system (doors slightly different on roof)

reply to post by Harlequin


Thanks for the vid it explains a lot... one thing I remembered from the PBS show was that hover test was conducted on a specially built platform... they take off on a steel grate to let exhaust gas vent off down and off to the sides... Basically they dug a hole and off to either side ran a large culvert pipe as a duct-work ...back to the hot gas stalling problem with VTOL...

Originally posted by grey580
Not a big deal. imo
there needs to be developed a deck coating.
maybe ceramic that will not pass the heat to the deck. or at the very least lessen the effect of the engine on the deck.

Your nuts!



Its a MASSIVE problem. Its a problem not easily solved either.


A quite remarkable oversight from those drawing up the specifications (in this case the US Navy and Royal Navy).

reply to post by Mondogiwa


That's one of the reasons that I specified 8 degrees. It is enough of an angle to remove the heat, but not enough to start the V-22 rolling. The brakes should hold it easily. This problem is occurring when the pilots are doing their full power checks before takeoff. It isn't as big a problem during landings.