Bell AV-22A Mamba

[kitnut617]

I would move the refueling probe to the nose.  Too close, even extended to the blades.  No room for error.

I have already been through this before and I'm not going to move the probe to the nose because it would have to be so long for the pilot to see the end it would look ridiculous  (the pilot sits in the back seat). Apart from that there's just no room in the nose and I don't want to put a 'scabbed on' one

EDIT (a bit later):

Here's a photo of a CH-53 in-flight refueling, the probe tip is inline the rotor blade tips.  Scaling this (and other photos), where I have my probe tip, it has more clearance than this set-up. The CH-53 has to be going at near full speed to keep up with the refueler which is limited to how slow it can go. So the rotor is tilted for forward flight at this speed.

[PR19_Kit]

Which was dropped in rubber to make a couple of castings. Although I've done a few casting, this was the first time I cast in some metal. In this case some brass round tubing to stiffen up the joint.

Oooooh, VERY techie! And what a super job you made of them too. 

[kitnut617]

Thanks Kit,

The corners of the trailing edge got a couple of air bubbles in the first casting, I thought I resolved the problem but when I did the second casting the same thing happened. I will have to look at how to do it a different way in the future but for now I'll just patch it up with putty, or even a blob of thick superglue ---

The particular point I chose for the cut was right where the flaps and flaperons join, so casting in this joint makes it a bit easier to detail.

The brass tube is to support the weight of the nacelle/prop-rotor, in my previous photos you can see a square of lead which is just being used as a counterweight to all the blades.

[nighthunter]

She's looking good!

[CammNut]

You could try a Grumman A-6 Intruder-style fixed refueling probe on top of the nose - well away from the proprotors, but close to the pilot's line of sight - but it looks fine where you've put it. I've never understood how the long, thin fixed probes as on the A-4 and Lightning never vibrated themselves off in flight!

[kitnut617]

Thanks guys,  the idea is that after the V-22 was flight tested, things got added on in an afterthought sort of fashion for the production versions. Things like radar scanners, refueling probes etc , they always look 'scabbed-on' to me (the A-6, Harrier or even the Buccaneer are a good example) . So with the AV-22, all these systems can be designed into the design from the get go.

The large radome on my project is because there's a large radar in there, along with all the black boxes needed for it. The idea is it's a multi-mode, phased array type and what looks like a FLIR turret under the nose is really a more robust EOTS sensor turret, remember this is for the near future not what has been so things don't need a 'wonder where we can put this now' sort of thinking.

[Weaver]

This looks great and I love the amount of engineering thought that you're putting into it.

The nose has a B-57G vibe to it, despite not having a single bit of B-57G in it....

One thing that strikes me, although it's way too late to change now, is that given the size of the sponsons and the space limits, it might have been more useful to make the stub wings almost as long and thick as the pods, i.e. to make them more like giant OV-10 Bronco sponsons. That would get you more volume for things like guns and ammo boxes in the stub wings themselves, which in turn would allow rockets to go in the nose of the pods, leaving more room in the bays behind them for Hellfires.

Speaking of guns, I'm a little dubious of the recoil effects of having a single GAU-8 that far from the centreline...

[MODE=PEDANT] The GAU-13 in the GEPOD-30 had four barrels, not six.[/MODE]

[kitnut617]

Thanks Harald, Flyer ---

H, I see what you mean about the B-57G, until I put some single colour paint on it, it didn't really stand out like that before.  I think it's where I made the bottom of the forward fuselage flat so the turret fitted to it.

And actually it's not too late to do something with the sponsons, they're not glued to the fuselage yet ----- I'll have a mosey around and see if I've got something like you've suggested, although the idea is the GAU-8 ammo barrel is fitted in the fuselage. I had thought about filling the nose of the sponsons with RP tubes too, but then there's no room for the Hellfires, which now might be Spear3's (I've found some on Shapeways).

I haven't got to it yet, but there will be a couple of pylons for some defensive missiles (Sidewinders or ASRAAMs) but not decided where they will go. I'm leaning towards the ASRAAMs as I could have two to a pylon using less space than the Sidewinders. I've recently read an article where manufacturers are looking at making the 2.75" RP's guided, it didn't go into specifics but I could see a miniaturized control system of the ASRAAM being used in the RP's.

[Weaver]

I haven't got to it yet, but there will be a couple of pylons for some defensive missiles (Sidewinders or ASRAAMs) but not decided where they will go. I'm leaning towards the ASRAAMs as I could have two to a pylon using less space than the Sidewinders. I've recently read an article where manufacturers are looking at making the 2.75" RP's guided, it didn't go into specifics but I could see a miniaturized control system of the ASRAAM being used in the RP's.

The guided 2.75" rocket is already in production and service:

https://en.wikipedia.org/wiki/Advanced_Precision_Kill_Weapon_System

The launchers are like standard Hydra 70 launchers but longer. The rockets have an extra guidance and control section incorporated between the warhead and the rocket motor. This has four flick-out guidance fins, each of which carries a laser-sensor on it's leading edge, the sensors' data being processed centrally to provide the equivalent of one large sensor (kinda analogous to the interferometer aerials used on Sea Dart and Talos to provide SARH homing without a receiver dish).

[kitnut617]

I haven't got to it yet, but there will be a couple of pylons for some defensive missiles (Sidewinders or ASRAAMs) but not decided where they will go. I'm leaning towards the ASRAAMs as I could have two to a pylon using less space than the Sidewinders. I've recently read an article where manufacturers are looking at making the 2.75" RP's guided, it didn't go into specifics but I could see a miniaturized control system of the ASRAAM being used in the RP's.

The guided 2.75" rocket is already in production and service:

https://en.wikipedia.org/wiki/Advanced_Precision_Kill_Weapon_System

The launchers are like standard Hydra 70 launchers but longer. The rockets have an extra guidance and control section incorporated between the warhead and the rocket motor. This has four flick-out guidance fins, each of which carries a laser-sensor on it's leading edge, the sensors' data being processed centrally to provide the equivalent of one large sensor (kinda analogous to the interferometer aerials used on Sea Dart and Talos to provide SARH homing without a receiver dish).

Just had a look at some photos of that, now that is just what this needs ---  thanks H'  So Spear3's for this will be bought real soon I think.

[kitnut617]

It's your build and a very good one.  If you look on the net you'll also find vid of that bird cutting the probe or drogue while refueling.  3:19
https://www.youtube.com/watch?v=BZV3Ffm2qIQ

That was my point salt6, they operate helicopters in very close quarters with the drogue basket, there's more chance something happening in the up-and-down direction than in the back-and-forward direction which is the scenario I have and I made my probe extend further forward for more clearance than what these CH-53 have in the up-and-down.

[Weaver]

It's your build and a very good one.  If you look on the net you'll also find vid of that bird cutting the probe or drogue while refueling.  3:19
https://www.youtube.com/watch?v=BZV3Ffm2qIQ

That was my point salt6, they operate helicopters in very close quarters with the drogue basket, there's more chance something happening in the up-and-down direction than in the back-and-forward direction which is the scenario I have and I made my probe extend further forward for more clearance than what these CH-53 have in the up-and-down.

I don't know about that. Forwards and backwards errors are pretty common in air-to-air refuelling. The Receiver has to approach the drogue by going forwards towards it, and if he misses, or turbulence moves it at the last second, then it ends up behind the tip of the probe. Station-keeping in the fore-and-aft axis is also more difficult, since it depends on throttle control (which is laggy and imprecise), rather than flying controls (which are precise and instant). You see a lot of footage of AAR where the Receiver creeps too far forward and the hose goes slack, and there's also a 'standard' accident where they pull back faster than the quick-disconnect can react and end up with a severed drogue on the end of their probe and fuel from the hose spraying all over their aircraft.

Having said all of that, some AAR probes (Mirage, Buccaneer) are very short and close to the windscreen, so clearance obviously isn't a big-enough problem to be a deal-breaker.

First video in this selection shows what I'm talking about: https://www.youtube.com/watch?v=QiN9M0ahfmM

[kitnut617]

It's your build and a very good one.  If you look on the net you'll also find vid of that bird cutting the probe or drogue while refueling.  3:19
https://www.youtube.com/watch?v=BZV3Ffm2qIQ

That was my point salt6, they operate helicopters in very close quarters with the drogue basket, there's more chance something happening in the up-and-down direction than in the back-and-forward direction which is the scenario I have and I made my probe extend further forward for more clearance than what these CH-53 have in the up-and-down.

I don't know about that. Forwards and backwards errors are pretty common in air-to-air refuelling. The Receiver has to approach the drogue by going forwards towards it, and if he misses, or turbulence moves it at the last second, then it ends up behind the tip of the probe. Station-keeping in the fore-and-aft axis is also more difficult, since it depends on throttle control (which is laggy and imprecise), rather than flying controls (which are precise and instant). You see a lot of footage of AAR where the Receiver creeps too far forward and the hose goes slack, and there's also a 'standard' accident where they pull back faster than the quick-disconnect can react and end up with a severed drogue on the end of their probe and fuel from the hose spraying all over their aircraft.

Having said all of that, some AAR probes (Mirage, Buccaneer) are very short and close to the windscreen, so clearance obviously isn't a big-enough problem to be a deal-breaker.

First video in this selection shows what I'm talking about: https://www.youtube.com/watch?v=QiN9M0ahfmM

Suffice to say then is they operated in close proximity and as you say not really a deal-breaker.

[kerick]

Nice video! I'm a bit surprised at how stable the droge is. Some great piloting skills.

[chrisonord]

Only just seen this Robert, I am really liking it. One for the Marines I think.
Chris