A recent anniversary of the first flight of the F-15E Strike Eagle was commemorated on a Facebook group and it got me looking through a variety of old shots I have of the jet. Having found a bunch of them that I liked, I figured I might share a few of them on the blog too. Here are a few of my favorites from over the years.
Within the very high speed flows of air in an aircraft’s exhaust, you can set up a series of shock waves and expansion fans as a result of the differences between the pressure of the flow and that of the surrounding air. When afterburner is engaged, the hot gases and the temperature changes these shocks and expansions cause, result in a diamond pattern forming in the exhaust plume. In darker conditions, these diamonds are more conspicuous but they are visible even in normal daylight.
These diamond patterns are a function of the flow being symmetrical since most engines have round exhaust nozzles. This isn’t the case for the F-22, though. It has flattened nozzles with a pointed profile top and bottom. This got me wondering what the effect is on the exhaust plume and whether the traditional diamonds are formed or whether the nozzle shape results in a different pattern of shock and expansions as they reflect within the plume. I decided to dig in to some shots to see what I could find.
I don’t have a lot of F-22 afterburner shots. While I have shot them a lot taking off, they often take off without afterburner. Since they have plenty of power and burner use dramatically increases fuel consumption (and the F-22 is not over-endowed with range as it is), there is no point using burner if it isn’t needed. Air shows are a time when they do give it plenty of burner, so that is the source of the shots.
The result of this is that there is definitely something unusual about the shock patterns. I include some shots of F-16 and F/A-18 afterburner plumes and the normal shock patterns that create the hotspots known as the diamonds are very obvious and simple in shape. For the F-22, things are very different with the patterns of hot zones being something more in line with the shape of the nozzle. The way in which the patterns repeat is more complex than for an axisymmetric nozzle. There is nothing much to conclude in these observations. It is just something that appeals to an old aero guy like me.
While researching some old images of mine from the experimental hangar at the USAF Museum in Dayton OH (the collection of which has since been moved into a new, custom build display hangar which is far more spacious), I saw some shots of something which, to be honest, I had no idea what it was. I took a look at the website of the museum to try and identify the type. It is a Fisher P-75A Eagle.
I did not knew Fisher existed and discovered it was part of General Motors. The configuration of the aircraft is quite unusual. The engine is mounted in the middle of the aircraft driving a contra-rotating propeller. The cockpit is further forward that on other single-engined fighters of the era since there was no space allocated to the engine up front. The underside includes a pair of inlets. The airframe is finished in polished metal rather than paint. Overall, it looks quite impressive. From what I read, another type was not deemed as necessary so development was terminated and they used the airframes for engine development work. Funny how I saw it on the visit and took photos and then promptly forgot about it.
NOLF Coupeville was scheduled for FCLP training and strong winds from the Southeast were forecast which suggested the right runway would be in use. I also had a day off scheduled. While the rest of the weather was potentially not ideal, I figured I would make the trip. Why. Not? They were due to be flying from late morning but, as seems to be usual, it was just after noon by the time things started to look active.
I was worried about the low cloud base but it was actually not a problem. The wind was really strong gusting 20-30 kts. This was giving them some interesting flying. Early on, there was a hint of sun sometimes which really helped the photos. As they climbed out after each touchdown, the skies behind made from interesting backgrounds and showed off the heat haze from the exhausts as well as the streaming tip vortices courtesy of the damp conditions.
After a while, I got a visit from the Navy Police. The young lad informed me I wasn’t allowed to photograph the jets. I pointed out I could be he was most insistent that I couldn’t. Rather than have trouble I decided the stop shooting. As it happened, the conditions got a bit worse anyway so I had got the best of what was on offer. I just watched the rest of the flying which included quite a few bolsters and some sketchy touchdowns as the wind got stronger.
Recently, the Blue Angels made their last formation flight with the F/A-18 Hornet. The team is transitioning to the Super Hornet ahead of 2021 and they have started working up with the new jets. It has been a while since I last saw the Blue Angels demonstration so I thought a few shots with their aging legacy Hornets was in order. They always got the oldest jets in the fleet so I hope they are happy to have some slightly newer airframes to work with.
Another throwback post today to some of the time I spent with Art Nalls and Team SHAR. Art is now selling his Harriers which is a big shame. No idea who will buy them (assuming someone will) and what will happen to them but I hope they fly again. The two-seater was close to flying again and I imagine there would be a few people interested in that.
I got a lot of shots with Art and the crew over the years but I recently found myself scanning through some detail shots of the plane. I even played with a few shots from a single position where I had experimented with moving the focus point along the wing. These seemed worth trying to focus stack. I hadn’t aligned them shots perfectly when I took them so it didn’t stack perfectly but it made a reasonable job of it. I hope to see this airframe again some time.
I can’t recall what prompted all of this but I found myself searching through my photos to see if I had any pictures of Avro Canada CF-100 Canucks. I knew I had seen one at the Imperial War Museum at Duxford but had I seen any others? I had been looking at the Wikipedia article on them as part of this theme and had seen where the remaining examples are. Turns out I had also seen one in Castle AFB museum. It’s a curious looking type but here are some shots including the IWM example from thirty years ago as well as last year.
The Growlers weren’t the only things flying at Coupeville while I was there. A bunch of bald eagles were also flying in the vicinity. They were crossing the approach path for the FCLP training which had me a little concerned. I thought they would get lost when the jets showed up but they clearly weren’t very concerned and were used the the jets. They might have got close but they seemed to stay just far enough away to avoid any conflict. A bird strike with a bald eagle would probably be messy for all concerned.
My trip to Coupeville to shoot Growlers undertaking FCLP worked out well as described in this post. What I didn’t emphasize in that post is just how close the road is to the north end of the runway. While southerly flow is not normal, when that is happening, you are very close to the action. The pano at the top of the post is the view you get of the runway from the road and plenty of people will show up to watch the jets bouncing.
The fields around the runway need to be looked after. There was a tractor cutting the grass while the jets were bouncing and you can see what a good view the driver probably had of the jets. I assume he had good hearing protection on while he was working in those fields. I also include a shot of a jet coming low over the field. Hopefully that shows just ow close everything is to the road.