Sunday, September 27, 2009

Warbirds at Cessnock: Albatros, Trojan and Avenger

After shutting down at Cessnock on our $100 wine bottle flight we noticed a nearby hangar with shiny warbirds inside: a T-28 Trojan, a Grumman Avenger, and two L-39 Albatros. All airplanes that rank far higher on the aviation coolness scale than our Piper Archer. But we love the Archer too.

We walked into the hangar and asked for permission to look at the warbirds from up close and snap a few photos. The friendly pilot in a flight suit invited us to join the guided tour, which for $10 each meant we could take as many photos as we wanted, sit in the cockpits and ask all our questions. Bargain.

Let me say it again: we were allowed to sit in the cockpits. In many aviation museums they won't even let you approach the airplanes, probably for good reasons. I've seen a small child hang with both hands from a pitot tube once. But today was different because this was not a museum, this was a hangar full of airworthy aircraft.

This is Ingo on the photo above reluctantly extracting himself from the Czechoslovakia-made jet trainer L-39 Albatros. The Albatros is a very popular aircraft with private owners since it is relatively cheap to maintain and operate as long as you are able to buy it in the first place. The cockpit has a definite military feel to it. The parts that do not have inscriptions in cyrillic characters on them are standard General Aviation avionics, such as the VHF-COM unit, transponder and ELT who are exactly the same models as in our Archer.

Not only are the two Albatros airworthy, they're also available for joyrides. This explains why we were allowed to sit in the cockpits. Just the age-old foot-in-the-door marketing technique: if at first you think $3040 is a ludicrous amount of money for 30 minutes of engine time, after having spent 2 minutes sitting in the cockpit looking at the dials you start thinking of reasons why this may not be so ridiculous after all. This is only 32 times as expensive as hiring a Piper Archer after all. Half an hour in a jet above Cessnock or a cross-country fight from Sydney to Ayers Rock? Entre les deux mon coeur balance.

The other side of the hangar contained a beautiful T-28 Trojan, this time from the other side of the iron curtain. It was used by both the US Air Force and the US Navy as a trainer, and saw some action in Vietnam. As is rather obvious from the photo below, it is a single-engine 9-cylinder radial engine driving a massive tri-blade metal propeller.

Climbing into the cockpit is surprisingly easy thanks to a number of handles and footsteps built into the (lowered) wing flaps. When sitting in the cockpit (did I mention we were allowed to sit in the cockpits?), the controls feel amazingly light, thanks to counterweights. The stick can be moved in all directions with only two fingers. I checked, the control surfaces moved accordingly!

The engine is an air-cooled Wright R-1820-86 Cyclone 9 radial engine, the same as on the B-17 Flying Fortress. A single row of nine cylinders delivers 1425 hp. The dark blue case in-between the cylinders and the propeller is a planetary reduction gear box which allows the propeller to rotate slower than the engine crankshaft. Propellers become less efficient when the linear speed of the blade tips approaches the speed of sound. Linear speed is proportional to the length of the propeller blades, and this is a rather large propeller, which explains why it needs a reduction gearbox while our Archer doesn't.

The last warbird of the lot was a Grumman Avenger. Just like the Corsair, its wings can be folded back for easy storage onboard aircraft carriers where space is at a premium.

Note the old-style attitude indicator with only a white line on a uniformly dark background to signify the horizon. No way to tell if you are up or down if you find yourself in an unusual attitude!

Near the center, right next to the "bomb bay" lever is the "wing folding" lever. It operates the hydraulic system which folds and unfolds the wings automatically, without any external help required. A very very cool training video explains the basics of piloting an F4U Corsair, including spreading the wings. A D-handle in the cockpit is used to lock the wings in place, it may be the same mechanism in the Avenger, I didn't check. The last few seconds of the video show the Corsair taxiing with the wings folded over the top. The Corsair was the fighter aircraft used by Pappy Boyington's squadron in WWII, made famous by the Baa Baa Black Sheep TV series.

I have to admit it is still a bit of a mystery to me how a folding wing can be structurally strong without a main spar going through the wing from the wing box all the way to the wingtip. We are talking about airplanes with no limitations on aerobatics and that can pull out of a dive with a load factor of 7G. All the load seems to be placed on the hinge pins that lock into place when the wing is completely unfolded. But then again, I studied software engineering, not mechanical engineering, so my knowledge is quite modest in that department.

On the photo below, the hydraulics on the right-hand side which control the wing folding mechanism, the ones on the left hand side operate the retractable landing gear, whose leg can be seen at the bottom of the picture.

Here again we have a radial engine, a Wright R-2600-20, but this time it's actually two engines rolled into one: two rows of seven cylinders each acting on the same crankshaft. The two rows are back-to-back, which makes cooling less effective on the back row since it gets less air than the front row.

I found a beautifully nerdy article about how Pratt & Whitney engineers managed to solve the torsional vibration problem caused by having two engines hammer the same crankshaft at a different position. The article relates to a similar engine, the R-2800 Double Wasp. More information that you would ever want to know, but you have to admire the dedication of the engineers who solved such a problem by trial and error, without any computer for simulating vibration modes.

All radial engines leak oil because not all of the bottom cylinders have their valves closed, and oil may also leak from other engine components such as push rods and rocker arms. I suspect the drip tray on the ground comes straight from your regular 4-burner gas barbecue. In the photo above the bomb bay and the cowl flaps are in the open position.

The Albatros flight may be expensive, but in comparison $1500 for 25 minutes in the T-28 sounds almost like a good deal. Too bad my wedding was last month, I would have happily added this item to the wedding registry. Anyway, I'm already very lucky to be able to fly smaller airplanes such as the Archer, so I'll stop here. But a loop, a slow roll or even a take-off in the T-28 must really be something special.

I should never have walked into that hangar. I should never have sat in that cockpit.


Marek said...

Impressive! I was just wondering which cyrillic characters you meant - I couldn't find any on the photos (and wanted to give my Russian reading skills a try ;-)).
It could be that Albatros was the first jet to fly on bio fuel, I think I read about it some time ago...

Julien said...

There's cyrillic characters on the face of some of the instruments. There were more in other parts of the cockpit than the front panel, I'll dig them up and put them in a new post sometime soon.

sylvia said...

What a great opportunity! I think you'll be back - maybe show them your blog and offer some free advertisement in return for 30 minutes in the air? :D

Julien said...

@Sylvia: I sure will be back, if only to look at the airplanes again. There's plenty of details I forgot to make a note of or photograph last time, and plenty of questions I still need to ask.

I have to admit the idea of a "blog vs joyride" deal crossed my mind, but I guess I'll need about one million clicks to have a decent base to start a negotiation from :-) But if anyone is listening, I'm open to the idea!

Mike said...

You were very fortunate to be able to check these great warbirds out from up close. Congrats!