Sunday, 30 January 2011

Tinkering with Tomcats

A new cat on the block
Ever since I moved my pictures to flickr at the expense of my account on MOCPages, I haven't looked at the latter site much. This morning I did visit MOCPages and came across a very interesting model of the Grumman F-14 Tomcat built by Joshua Ciesielski. He has some very flattering things to say about my Tomcats (much more about those later), but I first want to take a closer look at his model. The overall shape is reasonably accurate, but most impressive about the model in my opinion are the working features.

F-14D Tomcat model by Joshua Ciesielski.

The Tomcat was designed in the late nineteen-sixties as a replacement for the classic F-4 Phantom. The conflicting requirements of low landing speeds and a high top speed were met by Grumman by giving their design variable geometry wings. For low speeds and for long range cruise the wings were swept out, while for high speed flight (and storage aboard carriers) the wings were swept aft. Several aircraft that appeared around this time had this feature, including the F-111, MiG-23, Panavia Tornado and the B-1B. Among these the Tomcat stood out for being the only one where the wing position was computer controlled and the actuators were strong enough to move the wings whilst the aircraft was maneuvering, optimising the sweepback angle of the wing for the Mach-number (the ratio between the airspeed of the jet and the local speed of sound). This not the easiest thing in the world to get right on a LEGO model.

F-14D Variable geometry wings by Joshua Ciesielski.

The speed of sound plays a big role in the aerodynamics of jet fighters. Conventional jet engines require vast amounts of air in their intakes, but the flow at the front face of the engine should be should be below the speed of sound (the Mach number should be less than 1). If the plane itself is flying at supersonic speeds, this means that the air in the inlet needs to be slowed down, which is done by designing the inlet such that one or more shock waves occur in the flow.
Many modern planes have fixed intakes, but aircraft designed for high supersonic speeds such as the F-15 and the Tomcat the inlet performance is optimised for each Mach number (as well as a few other parameters such as the throttle setting and the air temperature) by changing the angle of a series of ramps built into the inlet. Much to my amazement, Joshua managed to fit moveable ramps in the inlets of his Tomcat.

F-14D Tomcat variable geometry inlet by Joshua Ciesielski.

In addition to these working features, the model has a retractable undercarriage covered by doors when retracted, working flaps, slats, rudders and tailerons (control surfaces), moveable air brakes, and an opening cockpit (although it doesn't quite open the way it should due to limitations of the canopies LEGO makes).

Tomcat evolution
I'm no stranger to Tomcats myself, so I can appreciate how much work went into Joshua's model. One of the first models of mine to appear on-line was my F-14D Tomcat model 'Vandy One', which I posted on brickshelf and MOCpages way back in 2005. It was also featured in an article in issue 2 of Brickjournal.

F-14D Tomcat model as it appeared in 2005.

It was the result of a gradual process of improvement that took place over many years. The picture below shows the collection of LEGO jet fighters that I had in around 1995. The Tomcat model I had at the time is on the far right.

Fighters (ca. 1995)
Fighter collection by Mad Physicist in 1995.

Comparing it to Vandy One it's obvious that there are many similarities. Whole sections of the model are built exactly the same. The differences, however, are more interesting. Note, for instance, the almost complete lack of SNOT building on the glove vanes (the sections between the jet intakes and the wing roots) and how crude the nose radome looks. The colour scheme of the old model is also noteworthy. Operational Tomcats were usually grey all over, but I didn't have enough grey LEGO at the time to build it properly. One thing that I did already have was a mechanism for synchronising the wing sweep, which has since been copied by several builders -including Joshua- and is shown below exposed on the latest incarnation of Vandy One.

Swing wings
Mechanism for synchronising the wing sweep by Mad Physicist.

In the years since I posted Vandy One on-line I've kept tinkering with my Tomcats, improving Vandy One and making similar changes to my second Tomcat model -an F-14A in markings carried by jets aboard USS Nimitz in 1978.

F-14D Super Tomcat (10)
'Vandy One' after its latest rebuild.

Vandy One received new wings -built using 2-3 wedge plates - and using other new parts the shape of the nose was modified yet again. The tailfins were completely rebuilt, giving their leading edge a more accurate slope. It also received new exhausts, replacing the older ones built with bricks and slopes and more closely representing the large afterburner cans of the F110 engines that powered the F-14D, and some of the stickers were replaced. The model that represented the older F-14A from Nimitz received new markings and new exhaust nozzles as well, representing the engine nozzles of the TF30 engines that powered most Tomcats.

F-14A Tomcat of VF-84 Jolly Rogers by Mad Physicist.

Finally, last year I got around to building a Tomcat in the grey markings that were most common on operational Tomcats since the early 'eighties, choosing to model an F-14A of VF-14 'Tophatters' that was aboard USS Enterprise in 2001.

Tophatters F-14A Tomcat (1)
F-14A Tomcat model by Mad Physicist.

Tomcats by other builders
The Tomcat turned out to be as much as a classic as the F-4 Phantom that it replaced and it is no surprise to me that it is a popular model to build out of LEGO. One of the first LEGO Tomcats that I saw on-line was Bryce Rollins'. He doesn't seem to be as active as he used to be, but back in 2005 he was constantly posting new models he designed in L-Draw, including many different Tomcat models. When I first saw them I was struck by how similar they were to mine, even though Bryce could have never seen mine. Great minds and all that!

One of Bryce Rollins' L-Draw Tomcat models.

Another 'virtual' builder is J. Stan over on flickr. In my opinion, one of the outstanding features on his Tomcat model (designed in Lego Digital Designer) is the way he slanted the intakes. It's something I tried on my Tomcat model many yeara ago, but couldn't manage to look good.

LEGO F-14A tomcat 12
F-14A Tomcat model by J. Stan.

LEGO F-14A tomcat 14
F-14A Tomcat model by J. Stan.

Another nice Tomcat model is the one by Scott Behne, also on MOCpages. I remember seeing this back when I was still a member and liking it back then, apart from some weirdness going on at the nose. It's still one of the best out there, also with slightly tilted intakes.

F-14D Tomcat model by Scott Behne.

Last but not least, for the last few years Mechanized Bricks have been selling a custom set of the F-14. It's not cheap, but is rather nice. Their site doesn't allow me to hot-link to picture, but I managed to find pictures of a built model (without decals) on brickshelf.

F-14 Tomcat model from Mechanized Bricks, built by Brickshelf user 3e3e3e.

Wednesday, 12 January 2011

Achtung, Messerschmitt!

ME 109 - 01
Many of the military MOCs I've built in 2010 were WW-II military aircraft. In fact, most of the aircraft I've built in about two years time are WW-II military aircraft. So, it'll be obvious that they interest me. So, what gets me to write something for the first time in months? Of course, a WW-II military aircraft!

Legohaulic built a very nice rendition of the German Messerschmitt Bf 109 a few years ago, but wasn't happy about the scale. So, he's had another go, with this very nice result.

ME 109 - 02

Note the subtle dihedral of the wings and the clever use of wedge plates to break up the camouflage!