Diamond Katana

reviewed by Philip Greenspun in March 2002

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The Diamond Katana is a 2-seat training aircraft with a European motorglider heritage. It is statistically safe, slow, forgiving, reliable, quiet, and cheap. You can buy an 80 hp Rotax-powered DA20-A1 for between $35,000 and $50,000 or newer versions with engines up to 125 hp for prices that approach $100,000. The Rotax-powered DA20-A1 can cruise at 95 knots indicated airspeed while burning just 3.25 gallons per hour. This article will concentrate on the 80 hp DA20-A1 because that's what the author has personally trained in (total of nearly 90 hours).

What is most addictive about the Katana is the visibility of the low-wing design combined with a plexiglass canopy. You feel as though you're part of the sky. With its constant-speed prop pulled back to 1900 RPM the interior is remarkably quiet and you're still cruising at 95 knots, just shy of the 104 knot standard cruise.

Pilots who regularly fly $500,000+ airplanes love the Katana. The examiner for my Private checkride was a 25,000-hour guy who has instructed on multi-engines and turbines. When I said that we were taking a DA20-A1 he said "I love the Katana; it is so much fun." My 1500-hour friend who owns a 240-knot Mooney Bravo also loves to goof around in the Katana and rents one whenever his Mooney isn't available.

The DA20-A1 cannot be IFR certified due to its lack of lightning protection.

Safety

The Katana has an excellent safety record. In the April 2001 issue of AviationConsumer.com the article "The Safest Trainer" (Jane Garvey and Paul Bertorelli) gives high marks to the Cessna 172 and the Katana. If you're unsure about the Rotax engine, you'll be comforted by this quote from the article: "The trainer with the best engine reliability record was the Diamond Katana, with only two engine failures, one of which was operator induced by lack of oil." Should you kill yourself in a Katana, you'll be the first American to do so. The plane's fatal accident rate of 0.2 per 100,000 hours is entirely due to a Canadian VFR-into-IMC incident. The AviationConsumer article does caution Katana pilots to ensure that the canopy is well and truly closed. Three in-flight incidents, none resulting in serious injury, have occurred due to pilots failing to latch the canopy fully. [The older Austrian-built DV20 had a different latching system imposed on it by the certifying authorities. Opening either latch would completely release the canopy. In November 2001 two people were killed in Wiener Neustadt when their DV20's canopy came open in the pattern--only 500' above ground level. The theory is that they wanted to pull in a trapped seat belt strap that was generating a lot of noise.]

No Diamond airplane has ever caught fire after an accident.

Preflight

Passenger and baggage capacity with the 20-gallon fuel tank full is about 460 pounds. Baggage is stored on a shelf behind the two front seats. A cargo net prevents it from coming forward and hitting you during radical maneuvers. There is enough space in the baggage area for at least two large duffel bags full of clothing, books, etc.

Preflighting the airplane takes less than 10 minutes. There are a couple of Plexi inspection panels underneath each wing where you can look for loose control rod nuts. For creaky 38-year-old me these involve kneeling on the tarmac. Wear bluejeans.

There are no power points for noise-cancelling headsets. There is no cigarette lighter outlet. You plug your headset into sockets just behind the seats and then step on the little metal step to get into the plane, something that can be easily accomplished without stepping on the leather seat.

At 6' tall, 205 lbs., I find the legroom and elbow space just barely adequate. You sit hip-to-hip with your passenger or CFI and if you're both putting on the 4-point harnesses at the same time, someone is going to get stuck in the ribs. Headroom is ample, even with massive Dave Clark headset bands.

Taxiing the Katana in a straight line via differential braking is an acquired skill.

Takeoff

Keep the center-mounted stick neutral, some right rudder in, and rotate smoothly at 51 knots. The Katana really wants to fly. If you're doing soft field takeoffs and hold the stick back all the way, you'll find that you go from rolling on the runway to stalling in the air within the space of an eyeblink. It is probably best to hold the stick no more than halfway back to avoid having to shove it forward in a panic for a reasonable soft field takeoff.

The 80 hp airplane climbs quite nicely from cold New England sea level airports but has a reputation as a dog down in Florida. Floridians also complain of baking underneath the canopy while taxiing out. When it is really cold, i.e., below -10C, Diamond recommends obstructing one of the cooling air inlets with a small metal plate. If you leave this in when the temperature is closer to 0C, climb out becomes very interesting. At maximum power, the engine temperature heads rapidly for the red but won't quite reach the red line. Any oil that you spilled during the preflight oil check starts to burn off and produce a burning smell in the cockpit. Your instructor calls the tower and asks for a precautionary landing. The smell goes away. The engine cools down. You taxi back and take off again. The engine temperature soars. Your 600-hour instructor begins to freak out again. You suddenly recall the existence and presence of that little plate. Not that this has ever happened to me ...

Cruise

When cruising you pull the prop back to between 1900 and 2200 RPM. In most Katanas this results in a substantially quieter ride. In some Katanas this results in a lot of vibration. Test before you buy.

The Rotax engine is water-cooled and therefore has more thermal mass than traditional air-cooled airplane engines. This means that you don't have to worry too much about shock cooling the engine when descending at very low power settings. The carburetor is auto-leaning, which means that you have only two engine controls: throttle and prop.

The Katana has only one fuel tank and a single on-off switch. The cruise checklist is very short: boost pump off, landing light off, power settings reasonable, gauges check, align DG to wet compass. There is no vacuum system so you don't have to worry about instruments flaking out. Everything is electric and very reliable in my experience. The narrow King GPS that was an option in most DA20-A1s has a user interface that is way too complex for in-flight operation. The moving map is monochrome and cryptic. Basically the King GPS is good for two things: (1) bearing and distance to a designated airport, and (2) one-button information about the 5 closest airports in case of a problem in-flight.

Sadly the Katana is not fuel-injected and therefore you really ought to apply carb heat periodically inflight. That's what the books say. However, despite having flown the Katana for 90+ hours in a medium-cold medium-wet Massachusetts winter, I never noticed that the carb heat had any positive effect on the engine. I.e., the Rotax does not seem to be prone to carb ice.

After 2 hours of cruise you'll notice that the fuel tank is more than half full and that your back and neck are starting to hurt. The Katana seat backs have a substantial and fixed recline angle. One's natural tendency is to crane one's head forward a bit to get a closer look at the instruments and the world outside. This is a huge mistake and will result in a stiff neck. Force yourself to lean back in your seat and accept the recline angle. Diamond makes this tough because there are no headrests in the DA20-A1.

Landings

Because it has huge wings (14:1 glide ratio) and no mass (1600 lbs. gross weight), the Katana is highly susceptible to crosswinds. If you can learn to land the Katana in a gusty crosswind, any heavier plane will seem remarkably stable.

The recommended approach speed is 57 knots, well above the 37 knot stall. If you're a sloppy student and come in at 65 knots you'll float an extra 500 feet or more down the runway. Coming in with half flaps to deal with that gusty crosswind? At 65 knots and half flaps, you'll glide an extra 500 feet over the numbers before you know it and then float an extra 500 feet. This is when you'll recall that best glide is 72 kts. and half flaps.

The landing gear on the DA20-A1 are fixed, simple, and strong. Students pound the stuffing out of the planes all day every day and the gear never seems to suffer.

Transport of Dogs

If your dog weighs less than 35 lbs., he can probably fit comfortably in the baggage area. A larger dog wouldn't be comfortable in the baggage area and might not be safe sitting in the right seat, due to the fact that the stick is part of the seat. It is a real shame.

Night Flying

Most of the instrument lighting comes from a couple of little bulbs behind the pilots' heads. The gauges are tough to read at night. If you do fly at night you might want to bring a passenger whose job is to shine a small flashlight on the engine instruments periodically.

The backlit instruments in the DA20s that I've tried are the following: wet compass, radio (includes a bar-graph VOR CDI), and the GPS. Basically I ended up using the GPS as my primary flight instrument due to its superior readability.

Winter Flying

It is difficult to remove snow and ice from a plastic airplane. If you can't get a hangar you'll have to use fabric wing covers during the winter months. This adds about 15 minutes to the already miserable cold and windblown experience of being out on the ramp.

Once in the air, however, the Katana is wonderfully warm and well-sealed. On sunny days the greenhouse effect from the canopy means that you won't even need to use the cabin heat.

Stalls and Spins

The Katana is very well behaved in a stall and can be maneuvered easily right down to its full-flaps stall speed of 37 knots. Even with most of the wing stalled, the ailerons remain functional. This can actually lead to some bad habits if the student moves to an older design or aerobatic plane. Most airplanes require "stepping on the high wing" with rudder.

The DA20-A1 is also spin-certified. Russ Hustead, renowned for his HK36R motorglider instruction (see www.skykingsoaring.com), previously instructed for 400 hours in the DA20. Hustead says "It is a great airplane for teaching spins and learning recovery. The Katana has a very vertical nose-down spin. Sometimes it takes about 1/4 turn to 1/2 turn to stop the rotation with opposite rudder."

The Continental-powered Version

Diamond produced 331 Rotax-powered DA20s in Canada from 1995 through 1998. Since 1998 the North American branch of Diamond has used only air-cooled Continental and Lycoming engines in its planes, not counting HK36 R/T motorgliders. The new DA20-C1s, which are named "Eclipse" and "Evolution" rather than "Katana", are substantially faster than the Rotax-powered DA20. If you fly from a hot high airport, i.e., in high density altitude air, the extra power would certainly be nice. But for most student pilots, power and speed is the last thing that is needed. The faster you fly the faster your small errors turn into big unintentional altitude and heading changes. Flying under the hood at 95 kts isn't so tough; try it at 135 kts in the new improved DA20 and you might find yourself all over the sky.

If you slow a DA20-C1 down to DA20-A1 speeds, the airplane will be comparably quiet inside, despite the Continental engine's lack of a constant speed prop. At maximum speed, however, the C1 will be noisier than a throttled-back A1. Everything else about the interior of the C1 is much plusher than the old A1s and you can get fancier avionics, e.g., Garmin 430 GPS, S-TEC two-axis autopilot. The C1 has 4-point harnesses like the A1 but they're on inertia reels. You can crack the canopy of the C1 for improved comfort when taxiing on hot days. The seat back recline angle on the C1 is less extreme.

Retail prices on the DA20-C1s range between $125,000 (stripped Evolution) and $170,000 (loaded-with-avionics Eclipse). Diamond also makes a version with the flight instruments in front of the right seat. This is the airplane used by the United States Air Force for primary flight training at the Air Force Academy.

The Katana 100 Version

The Katana 100 is a factory retrofit of a DA20-A1 with a brand new 100 hp Rotax 912S. This yields a useful load increase of 44 lbs, to 1654 lbs gross. Conversion also entails improved cooling, various new and improved parts, and a complete mechanical and cosmetic refurbishment. It costs about $30,000 and the airplane comes out looking like new.

One option for the budget-minded owner is the following:

Maintenance

Mechanics at Hanscom Field report that the DA20-A1s are easy to maintain. Unlike a metal airplane they don't have a lot of inspection panels so a 100-hour inspection can be done in as little as one day. The Rotax engine will be unfamiliar to the vast majority of American airplane mechanics. Thus, if you plan to fly around in the boondocks and get oil changes or 100-hour inspections, the Continental-powered DA20 is going to be easier to live with. The Continental will go 2000 hours between overhauls and the Rotax just 1200.

Owners report that they do their own oil changes on the Rotax 912 and that it is easy. Best to change oil every 25 hours to prevent lead fouling, with an oil filter change every 50 hours unless you fly infrequently, in which case the filter should be changed at 25 hours along with the oil.

Factory support for spare parts is apparently very good.

Personal Conclusion

Despite my positive experience as a flight student in the DA20 and its low price and operating cost, I decided not to buy a DA20. Although my main goal is to fly day VFR and see those aspects of the world that aren't visible from the ground, I want the option of flying IFR and flying comfortably at night. More importantly, I want a back seat so that I can bring my dog Alex with me. So I shelled out about 5X the cost of a used DA20 on a brand-new four-seat Diamond DA40.

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Text and photos (if any) Copyright 2002 Philip Greenspun.
philg@mit.edu

Reader's Comments

Hello Phil,

A friend and I rented a DA20 for 24 hours in Scottsdale, AZ back in the late 90s. During our one-hour check rides, we found it to be an exceptionally stable and enjoyable airplane to fly, remaining fully controllable with the stick all the way back in my lap in a what passes for a stall in a Katana. When I say we rented it for 24 hours, I mean we had the plane for 24 hours straight for a single flat rate. We only had to purchase our own fuel but could fly for as many hours as we could get in during the 24-hour period.

The simple GPS provided a single line of digital text! We flew from Scottsdale to Albuquerque for a nice brunch, on to Page (KPGA at the edge of the Grand Canyon), then finally landing in Flagstaff at sunset (this was a day-VFR version). We had to climb the airport fence the next morning in order to get out at sunrise and have the plane back to Scottsdale in time to meet our 24-hour deadline. I think we paid $200!

It was the trip of a lifetime, and these many years later I am shopping for a Katana.

Thanks again for your very informative web page.

Mike Stiteler

P.S. I was surprised to find the differential braking fairly easy to master.

-- Mike Stiteler, December 5, 2008

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