Monthly Archives: January 2016

Interesting Raptor Control Inputs

It might be a long time ago that I did anything closely related to the engineering of fighters but there is still a part of me that is a stability and control type of guy. Watching the control inputs and responses of planes is cool as far as I am concerned. With the advent of fly by wire designs, there was considerable scope to play around with the use of the control surfaces to achieve different aims. With no direct linkages to the stick, the pilot can be totally unaware of the choices the system is making for control combinations.

The engineers may have chosen to program the trailing edges to have different deflections inboard and outboard to offload the outer portion of the wing for example. The F-22 makes use of a variety of interesting control inputs. For example, it doesn’t have a traditional speed brake. I assume this was removed for stealth reasons. Instead, the control surfaces move counter to each other. You may have inboard flaps going down and outboard flaps going up. The moments cancel out but all increase drag incrementally so the effect is like having a speed brake deployed.

Since the aircraft is also unstable, you may have tail deflections that seem at odds with the maneuver being flown. During the Chino show, the usual routine was flown (usual for an F-22 but not many other jets) and, as I look through a bunch of the shots, I see some quite unusual control inputs. If you are in to such things, these may appeal to you. Gary, are you reading this?

Cool Bench

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Just a quick picture from the gardens at Chatsworth. An old tree trunk had been sculpted to make a rather cool double sided bench.

Windy Day at SFO

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The winter brings days with clear skies and nice light angles. That is not all it brings, though. It can mean strong winds. One of my visits to SFO last year coincided with some very strong winds. The wind was gusting over 40kts on a regular basis. This was far to strong to allow operations on all of the runways. With the wind almost directly down the 28s, those runways were in use for arrivals and departures.

The wind might have been strong but the conditions weren’t bad for photography. The sun was actually out and the light on the planes was pretty nice. However, using a long lens was a bit more tricky with the wind since it tended to blow the lens around a lot. I spent a lot of time trying to stay in the lee of a tree to shield myself from the worst of the gusts.

Consolidation of all operations on the two runways meant that things could get pretty congested near the thresholds. Plenty of jets were lined up ready for departure in between the arrivals. Having so many jets up there is relatively unusual. It is a bit problematic for some shots though. The arriving jets are behind those awaiting departure slots. The waiting jets produce a lot of distortion from the heat of their engine exhausts. This can be quite frustrating since the number of jets means that clear space for a shot is limited.

There are more benefits of course. Having very strong winds straight down the runway means the departing jets have a big advantage. Nearly 40kts on your ASI while standing still means a lot less ground roll is needed to get airborne. The narrow bodies were jumping into the air long before they got off peninsula extending the runways out into the bay. The same was true for the wide bodies. The heavy 747s always have a longer roll but they were getting up before the cross runways. The big twins were getting up very quickly. I had a pretty good view of the 777s as they departed and got what is probably my clearest view yet of the truck rotation on the 777-300ERs – a quest familiar to the regular readers.

Fighting the wind made for a tiring day. I decided I would wait around until the Virgin 787-9 showed up and then call it quits. This was due to be one of the last big arrivals prior to the sun disappearing. When it came in, the light was very nice. I got some good shots and then packed up to go. Going back through the shots since, it was quite clear that the wind was a big factor in my shooting. The sharpness of some shots suffered but the bigger issue was tracking accurately. Far to many extremities of planes got chopped off. Despite, that, the opportunities a day like that offers made it well worth doing and I would be back in a heartbeat if the conditions come together.

Hovertravel Have a Busy Day

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Another Isle of Wight development is the hovercraft. Much early development of the concept was done on the Island and many were produced in East Cowes. Hovertravel still provide a frequent service between Ryde on the Island and Southsea on the mainland. I got a couple of opportunities to shoot these hovercraft while visiting. On the day Pete and I went flying, we arrived over Ryde just as one of the hovercraft was coming in. Another was parked on the slipway at the time.

When we left the island, I headed up on the upper deck of the ferry to see what was going on and had two over the hovercraft come by in opposite directions. It was rather windy up on deck but I was able to get some usable shots of the two of them individually and as they crossed. Apparently, Hovertravel are in the process of acquiring new craft to replace the current AP1-88s that are in service. Given that they were built in the late 1980s, they have provided good service. It will be interesting to see what replaces them. I wonder whether the new vehicles will arrive before I next get back.

Coin Tree

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I’m not sure whether to categorize this as in interesting oddity or vandalism. While walking in the Lakes, we came across this tree. At a distance I thought it was an interesting type of bark but, once you get closer, it is clear that the tree has coins jammed into the surface. I have no idea how or when this started or even why it did. Obviously, a lot of people have jumped on the bandwagon and now there are so many coins embedded in the wood that I couldn’t see the point of even trying to estimate how many there were. Instead, we just checked the whole thing out and then went on our way.

Ripples in the Skin

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The construction technique for aluminum aircraft fuselages is known as semi-monocoque. A monocoque structure takes the entire load through the shell of the structure. In airframes, the skin is very thin and so frames and longerons are joined to the inside to provide additional rigidity while the skin still takes a lot of the load. If you haven’t ever seen the cross section of an aircraft structure, you may be surprised to see just how thin the skin panels actually are. They are perfectly up to the task of pressurization and bending loads so no need to panic.

An outcome of this design approach is that the panels between the frames and longerons can experience some load directions that induce a measure of buckling. Nothing that is beyond their elastic limits but something that can be apparent if the light comes from the right angle. The lower side of the rear fuselage of the Boeing 757 is an area that is susceptible to this in certain flight conditions. I saw a number of them recently – both -200 and -300 models – and they both were showing visible distortion of the panels. The sun angle meant that the shadowing of these areas was apparent.

The 757 is by no means the only aircraft to experience this phenomenon. The B-52 Superfortresss is a jet that shows this effect on plenty of occasions. I have heard people comment on it being a function of the age of the airframes but it is more of a result of the design of the basic structure than anything else. Certainly nothing to be immediately concerned about.

Rainbow Fireboat

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During the Parade of Ships for San Francisco Fleet Week, the first warship was led by a fireboat from the City. It sprayed water from its hoses to provide a focal point to the parade. As it got closer to us, the angle of the light and the mist from the fire hoses resulted in a clear rainbow forming in front of the fireboat. It looked pretty cool and I am not sure the photos really do it justice. However, here is a shot to show you pretty much what we saw.

Did Anyone Bother With This Livery Design?

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Not long ago I complained about the dirty condition of a China Eastern A330. At the time, I thought it might be a non-standard jet because the livery was basically white with a couple of distinguishing marks. It turns out that I hadn’t appreciated that China Eastern have replaced their previous colors with a new and less colorful scheme. Since then I have seen some 777s come in with the new scheme. In an era of relatively bland airline colors, it seems to me that China Eastern have gone a stage further and taken any interest at all from the livery. Not a cool effort on their part I think. They should check out what China Southern is doing by comparison.

Grotto Pond

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Exploring the grounds of Chatsworth House took us to places we had not seen on previous visits. Even if you exclude the majority of the estate and just focus on the organized garden areas, there are so many parts to see that it is easy to overlook them. This is why, despite having been to Chatsworth on a number of occasions, this time I saw areas that I had not seen before. One of these was the Grotto Pond.

Because this area is one of the furthest away from the main house, the number of people making their way that far out is pretty small. It is not deserted by any means but it is pretty quiet. This is ideal given how tranquil the setting is. It was very easy to just stand and look. Given how far out in the country you are, there isn’t much background noise so you can let your mind wander…

JetBlue’s 200th Aircraft

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The repetitive nature of the same airlines and the same types is what you expect of airports these days. Every once in a while, though, the airlines put some extra decoration on their aircraft. Usually you can see that there is something there before you get to see what it actually says. JetBlue have an Airbus A321 that is apparently their 200^th aircraft. It has a big decal on the rear fuselage to highlight this fact. It apparently joined them over a year ago so a bit late for congratulations.