Tag Archives: Helicopter

The Chogenbo is coaxial coolness

Over the years several people have constructed mechanisms to get coaxial rotors on their helicopters to spin in opposite directions, including Henry Oberholtzer. Recently one of his ingenious creations was successfully adopted by Matt Hacker for his AH-5 “Chogenbo” (Japanese for Kestrel). The end result is one of the coolest and most believable near-future helicopters that I have seen in a long time. Matt unveiled the model at Brickfair Virginia in August, where it won the ‘Best Military’ category. I have been eagerly anticipating him posting pictures of it ever since.

AH-5 "Chogenbo"

Let me apologise for the info dump in advance, but there is no denying that I am a bit of an aviation geek. (It’s fewer than 4000 words, I promise.) Coaxial helicopters are cool. There is a fundamental limit, of about 400 km/h, to the forward speed of conventional helicopters. This is essentially set by the blades being swept forward reaching the speed of sound -this is a bad thing- and the blades being swept aft, also known as the retreating blades, moving too slow through the air to generate lift. This is called a retreating blade stall and is also a bad thing. That going faster is difficult is evidenced by the longevity of the current record, set by a modified Westland Lynx as long ago as 1986. If you want your helicopter to go faster, you’ll have to get creative. However, coaxial helicopters, with two sets of counter-rotating rotors on top of each other, do offer the promise of considerably faster flight. The retreating blades on a coaxial helicopter do suffer from retreating blade stall, but the resulting loss of lift is compensated by the lift generated by the blades of the other set on the same side of the helicopter moving forward. To see the coaxial rotors on Matt’s helicopter in action, check out his video.

To snare a wolf

A lot of people start their builds by fiddling around with a few pieces until they find an interesting-looking combination. This then becomes the starting point for a cool new mecha or spaceship. That’s not how I do things. For most of my models, I start by planning, followed by a lot of procrastination and getting side-tracked into building other (easier) things and then some more planning, lather, rinse, repeat. Once I start putting parts together things move quickly, but the planning process can take several weeks or, in the case of Airwolf, as long as two years.


In the eighties, starting with Knight Rider, there were several shows that featured some sort of hi-tech vehicle as a central plot device or even as a character. Both Blue Thunder and Airwolf featured helicopters, but Airwolf was definitely the better show. It had one of the best theme-tunes in the history of television and, though they now appear terribly dated, the plots were a bit darker and more interesting than in most of the other shows, often dealing with espionage and the Cold War. Furthermore, the helicopter itself was based on the super-sleek Bell 222 and was armed to the teeth, with retractable guns and a ventral missile launcher.
The reason why the process took so long is that I don’t start building until I have convinced myself that I can build the model to a suitably high standard, which in this case meant building that sleek shape and those cool retractable weapons. What finally sealed the deal was finishing Blue Thunder, the realisation that I could replicate the shape using various new curved parts and by hinging the cockpit windows, as well as a video I saw of the missile launcher retracting on an RC model.

He is out there... Blue Thunder

Our resident Lemur recently got asked how contributors to this blog are selected. Of course, much of the process is top-secret, but I’m pretty sure a contributor should add something new and distinctive to the team, even if that something new and distinctive is a cute bushy tail and a willingness to take care of the paperwork. However, most of us share that we got into this because we like building our own models. Fan-built models are the bread and butter of this blog and knowing a thing or two about building definitely helps.

In the last two years, I have been working on a large collection of movie and TV vehicles. I have close to fifty of them now, but there are still plenty of cool and interesting examples left that I haven’t built yet. I already had a jet, but I did not yet have a helicopter, for instance. With Blue Thunder, that has now been rectified.

Blue Thunder

Blue Thunder was a fictional high-tech police helicopter that starred in the eponymous 1983 movie. Its pilot was played by Roy Scheider, who is probably better known for his role as the police-chief in Jaws. The movie lead to a short-lived TV series, which I used to watch religiously as a child. Although the plots of the episodes and the dialogue were undoubtedly cheesy, the helicopter was one of the coolest things ever. It didn’t talk or have a red light scanner bar, but it had a tail-mounted fan instead of a conventional tail rotor and a Gatling gun that was slaved to the pilot’s helmet. Two flyable helicopters were used in the filming: Aerospatiale Gazelles, painted in a largely dark blue colour scheme and modified with a nose-mounted pod housing sensors and the Gatling gun, an ‘armoured’ cockpit canopy consisting of flat panels and a few other gadgets.

Blue Thunder

The cockpit canopy was the trickiest bit of the build. Building a rectangular structure is fairly easy. Building something that is rounded is also doable, by stepping plates or by using combinations of slopes. Building a faceted structure, however, is just plain awkward and getting it more-or-less right took a lot of trail-and-error.

Chinook, RAF-style

Compiling lists of parts that people would like to see LEGO make is a popular pastime on LEGO-related internet forums. However, sometimes it is overcoming the limitations of the available parts that makes building with LEGO worthwhile and the end result remarkable. Case in point: this Chinook HC.2 built by Simon T. James, known in the RAF as a `Wokka’.

Chinook HC2: door-to-door delivery (9)

Like his Merlin (which was blogged here last year) he built it in dark green. This is a decent match for the colour the RAF paints its helicopters. The parts palette may be growing, but it is still a fiendishly difficult colour to build with and the `Wokka’ doesn’t have an easy shape to start with.

Get To Da Choppa!

It’s been quite awhile since I’ve built anything with my own Lego, but I’m going to post something anyways. I built this light transport helicopter months ago, and have finally managed to get the photos together. I tried to spice things up with a little scene this time, although it may be too little for the helo.

Sparrowhawk Light Attack Helicopter 47

I’m a big fan of tilt-rotors, though I hear this is properly called a tilt-wing. Either way, the tilting adds a fun little activity, when swooshing this thing around.

Focke-Achgelis Fa 223 – world’s first production helicopter

Though not the sort of achievement that makes me proud to be human, the Focke-Achgelis Fa 223 “Drache” (Dragon) was the first helicopter to enter production, though Nazi Germany was only able to manufacture about 20 during World War II. I had no idea it even existed until Aleksander Stein built one from LEGO.

LEGO Focke-Achgelis Fa 223 helicopter

Here’s Aleksander’s Fa 223 in action over southern Bavaria:

LEGO Focke-Achgelis Fa 223 with diorama