Compound Helos

[Hunt3r]

As some might know, there's a certain helo called the X-49A Speedhawk, which is basically a UH-60 with a ducted rotor to replace the tailrotor, and longer wings.

Basically, a chopper that goes faster that looks funny and has stubby wings (Think Mi-24)

There's also plans to do the same for the Cobra and Apache. Naturally, this means longer stubwings, and therefore more weapons.



The X-49A Speedhawk.



Cobra



Apache!



Think of it... Apaches and Cobras with 38 Hydras and 16 Hellfires... or 24 Hellfires, or 114 Hydras, along with their cannon. Also, more range and faster. Looks to be good.

Think AH-56, but instead it's an Apache with a ducted fan.

[waldo_ii]

I watched a video of a X-49, I wasn't impressed. The rear propeller assembly seems awfully heavy. During takeoff and near-hover, the aircraft did not pitch below ten degrees above the horizon. During forward flight, it never seemed to pitch forward more than ten or fifteen below the horizon. The video seemed to avoid showing the aircraft in a stable hover. Now that I think about it, when it showed the aircraft going at low speeds, there wasn't anything else in the frame to give a point of reference. The torquing effect of the rotor likely makes hovering quite unstable. I cannot imagine such an aircraft being employed, at least not unless the rear propeller assembly is lightened and the helicopter is better stabilized.


The increased lift ability would only really be in effect when the aircraft is at cruising speed. During a hover/during vertical ascent/descent, the advantages of the rear-facing propeller are none. Unfortunately for whatever company made these prototypes, much of today's attack helicopter tactics rely around low altitude hovering.


Don't forget about wind. Hovering helicopters have a tough enough time with crosswind. The awkward answer to the torquing effect combined with the weight of the assembly would make matters worse.

[SkaterCrush]

I think the Osprey is an overall better idea, if they were going to do something like this is would be a much better idea to make a brand new helicopter, not modify an existing helicopter or copy one.

[Hunt3r]

Originally Posted by waldo_ii

I watched a video of a X-49, I wasn't impressed. The rear propeller assembly seems awfully heavy. During takeoff and near-hover, the aircraft did not pitch below ten degrees above the horizon. During forward flight, it never seemed to pitch forward more than ten or fifteen below the horizon. The video seemed to avoid showing the aircraft in a stable hover. Now that I think about it, when it showed the aircraft going at low speeds, there wasn't anything else in the frame to give a point of reference. The torquing effect of the rotor likely makes hovering quite unstable. I cannot imagine such an aircraft being employed, at least not unless the rear propeller assembly is lightened and the helicopter is better stabilized.


The increased lift ability would only really be in effect when the aircraft is at cruising speed. During a hover/during vertical ascent/descent, the advantages of the rear-facing propeller are none. Unfortunately for whatever company made these prototypes, much of today's attack helicopter tactics rely around low altitude hovering.


Don't forget about wind. Hovering helicopters have a tough enough time with crosswind. The awkward answer to the torquing effect combined with the weight of the assembly would make matters worse.

Eh, just so you know, the thing is actually quite good when it comes to hovering.

It's actually better for hovering, better at NOE, and it can hover while pitching up, which means you only have to unmask your radar (referring to the Longbow), and then you can actively track and shoot while presenting a far smaller target.

YouTube - Piasecki X-49A Speedhawk flight tests

I'd hedge a bet though, that it only looks heavy. Composites would actually make it quite light. You'd also be able to turn on a dime infinitely with this system.

The only potential problem would be limited vertical climb performance, which shouldn't be hard to remedy.

Also, yes, it'd be better to have this be for an all new helo, but the point is to retrofit existing ones for better performance. Keeping existing avionics and engines means less retraining for crews that have to fly the things.

As long as there is little need to add another engine or something to keep it working, there's no problem at all. The Osprey, keep in mind, is an airplane first. I personally think it's quite bad of an idea to trust a tilt-rotor.

Boeing is actually backing this, and the plan is to make them more effective at hot/high ops (Think Afghanistan) by adding a THIRD engine. It seems like the range is still larger then the current UH-60.



This is the most current picture of the X-49A, and apparently if they go into production, the wings will be mounted up high to keep it squaddy proof.

The company working on this is doing it in conjunction with Boeing, and they receiv3e more funding when they get more of it done. Also, concept pics for a compound helo Chinook and Viper:







Not to mention, the current UH-60 can only really go at about 120 KIAS, and that's going to be a ride rough enough that you can't read your instruments.

Also, an armed Osprey isn't really the option you want. The Army and SOP are interested in compound helos because they can be an escort to the Osprey.

[Expendable Grunt]

I'm not going to pretend I know enough about helicopters to make an educated expression, but that looks like a damn cool design.

Also, a nasty target.

M.

[Hunt3r]

Meh, helicopters are huge targets already.

Besides, you now have a huge shroud that can be armored or made from composites, which means you now have a very tough piece of armor between the prop and the bullet.

[cyberzomby]

Yea how will this effect there rotation when hovering if they even can hover at all now? I mean, that was the point of most attack choppers right? So they can hide behind a hill and pop up, shoot and move away? Dont we have JETS for the role these helo's get bumped in?

[Hunt3r]

Originally Posted by [R-COM]cyberzomby

Yea how will this effect there rotation when hovering if they even can hover at all now? I mean, that was the point of most attack choppers right? So they can hide behind a hill and pop up, shoot and move away? Dont we have JETS for the role these helo's get bumped in?

Basically, it automatically deflects the wash from the ducted fan to compensate for torque of the rotors spinning.

As said before, there's a video of it hovering. Because the ducted fan is blowing air, the pitch required to keep it in a stable hover is about 10-15 degrees for the Apache.

The advantage is that you can now launch behind cover if there is a lase. Hellfire flies from cover, finds laser, and off it goes.

This is basically the same deal as the Cheyenne, which can go at 216 knots. Compound helos are in essence a helo with a pusher prop and some stub wings.

They can hover, they can do anything a standard helo can, except with a payload penalty that is resolved by more power or a rolling takeoff

Once again, here's the video to show what the current X-49A can do:

YouTube Video

[Expendable Grunt]

So forward motion is now entirely because of the back prop thing?

M.

[[R-DEV]Masaq]

Originally Posted by Expendable Grunt

So forward motion is now entirely because of the back prop thing?

M.

Mostly from the ducted prop and the stub wings, yeah. In forward flight the main rotor spins just fast enough to counteract the drag effect it produces, assisting with lift.