3D TVC On One Engine

From what I've seen, only jet aircraft with two engines possess 3D thrust vectoring. Using a similar nozzle on a jet aircraft with one engine yields only 2D thrust vectoring because the differential pitch vectoring of two engines can lead to roll control in an aircraft with two engines.

However, I've thought of a couple of nozzle designs that could yield 3D thrust vectoring on a single engine. One has four paddles, and the other has six.

A diagram is attached to illustrate my concepts.

Now I must ask if you think either of these designs would work? Would they be cost-effective? Would there be any particulary difficulties in their construction or repair?

Accidental double-post. Could someone delete one of these threads?

You do NOT NEED 2 jets to do 3d maneuvering.

The X-31 has been doing it with one jet for years.

Here is a good, short, YouTube clip that shows a 3D maneuver:
http://www.youtube.com/watch?v=GhonVYFIiP0

X-31 Wiki:
http://en.wikipedia.org/wiki/Rockwell-MBB_X-31

And the X-31 does it with only 3 paddles.

And they've done it with an F-16, both GE with the AVEN and PW with the PYBBN.

No paddles here though, but a full nozzle. (Paddles are not very efficient)

Here is an old video of the VISTA w/AVEN: http://www.youtube.com/watch?v=XZQDwRKHCSQ

How does the X-31 achieve roll control with 3 paddles?

No roll, and sorry - roll wouldn't work very well with a paddle arrangement as shown above either. The paddle method was crude, heavy, and cumbersome. (See the attachments on the Hornet below) They could be incorporated into the design of the engine nozzle, but you'd be loosing thrust through the gaps between your flaps, especially when they were deflected in opposite directions to gain roll.

With the force being applied so close to center line of the engine, the force would be very limited. (Why ailerons are located at wing tips and not the root.)

The best way for true "roll" would be two engines spaced wide apart that would vector up/down respectively. The further apart the motors the greater the roll force.

If you notice the Raptor's engine nozzles both vector together. (not differentially for roll) Roll is controlled by those massive control surfaces.

Even without a "tail" an aircraft would need wings, so you'll always have a control surface of some type on it.

My if 2D thrust vector was so important (or required to survive), and didn't impart a weight/complexity penality it would have been used on the F-35.

FYI - Variable nozzles need to be overhauled on most engines earlier than any other part of the engine. The heat/blast/pressure of the augmentor kills those parts fast. They have gotten much better over the last 20 years, but they have a long way to go.

Keep 'em flyin'
TEG

With the force being applied so close to center line of the engine, the force would be very limited. (Why ailerons are located at wing tips and not the root.)

The Flanker models have widely-spaced engines. Is this one of the contributing factors to their high maneuverability?

If you notice the Raptor's engine nozzles both vector together. (not differentially for roll) Roll is controlled by those massive control surfaces.

Really? The official website for the F-22 says that the TVC increases the aircraft's roll rate by 50%. How can roll rate be increased if the nozzles cannot pitch differentially?

http://www.f22fighter.com/engines.htm#F119

Kryptid wrote:The Flanker models have widely-spaced engines. Is this one of the contributing factors to their high maneuverability?

I thought they pitch too, anyone to confirm? The MiG's new TV nozzles may act differentially, but I haven't seen enough of it yet to tell.

Kryptid wrote:Really? The official website for the F-22 says that the TVC increases the aircraft's roll rate by 50%. How can roll rate be increased if the nozzles cannot pitch differentially?

The F119 nozzles pitch TOGETHER on the Raptor but do still give additional roll control... I'll explain.

The horizontal tail surfaces or "stabilators" on the Raptor/Eagle/Viper/Flanker perform pitch and roll (together/differentially) The use of thrust vector for pitch control allows the stabilator to give more roll control.

Example: If your stabilator gives 50% pitch and 50% roll during maneuvers, it can now give 100% roll as the pitch is driven by the thrust-vector. So yes a Raptor will roll 50% better with it's TV.

Keep 'em flyin'
TEG

In my view the F-35 family should have been designed with a 2D thrust vectoring nozzle but this may have been impossible with the F-35B. If there was no way around that they should have either fitted them to the F-35A and F-35C anyway or developed a semi-stealthy (like the LOAN nozzle) 3D thrust vectoring nozzle for the F-35A and F-35C.

I believe the F-35 team decided that thrust vectoring was too heavy, too complex, too expensive, and too maintenance intensive. The pros for TV outweigh the cons for the next generation "cheap fighter."

I'd also venture to say the massive size of the F-35's control surfaces will keep them effective below the stall speed of the wing, which would further reduce the need for TV.

Lets also not forget that neither the Block 52+ nor Block 60 Vipers have TV even though both PW and GE developed them for their engines.

Keep 'em flyin'
TEG

I will say these nozzle concepts are quite interesting to see. However, I'm not a propulsion engineer so I can't say whether or not they're viable.

I would question the complexity (both software development, hardware, FLC intergration along with control surfaces, maintenance issues etc.) and effectiveness of having so many "petals" (size?).

So if one wanted to use TVC to provide a rolling moment, one would be better off having two engines widely spaced apart than having them close together? This makes me wonder why the MiG-1.44 has very closely-spaced engines despite the fact that it was meant to have 3D TVC.

That's simple physics. The further from the center of mass a force is applied, the greater the moment applied. Think of it as leverage. If all you cared about was roll effectiveness you'd have the nozzles at the wingtips!

Do any of you guys have some good quality photos of the 3D thrust vectoring nozzles tested on F-16?

Would it be possible to design a stealthy 2D thrust vectoring nozzle like on the F-22 that could tilt downwards and work for STOVL operations on the F-35B? Also how does the LOAN nozzle compare in terms of RCS when compared to design used by the F-22A?