Nighdrag

I bumped into a paper from an old article from Sports Aviation magazine on advice for flying taildraggers called "Taming the Taildragger Pilot" by Budd Davisson (EAA). The advice in this article really clicked with me, and applying its lessons in how to dance on the rudder has allowed me a 100% non-lethal takeoff rate in the Dora. The main takeaways from the article for me: ...the correct method of using the rudder is to displace or tap it slightly. As soon as the nose starts moving in that direction, it’s going to be neutralized and the other foot gets ready to jab rudder to stop the nose where you want it. So, you initiate the turn with a slight jab in one direction, stop it with a slight jab in the other direction. If at any time in that sequence the rudder pedal is pushed too far down or held for any length of time, the pilot can be guaranteed of a swerve in one direction or the other. [in the Dora, it will just tip over the main gear and drag the outside wingtip -- Nighdrag] You ought to treat the rudder pedals as if they are red hot. You’re just going to hit them as long as you can stand the pain and get off of them immediately. Also, the duration of the jabs is in inverse proportion to the speed – the faster the airplane is moving, the less rudder pedal it takes to make things happen. Once the tail starts getting light, my technique is to be on the pedal and immediately off it. More than the P-51, the Dora's nose moves noticeably later after rudder application, and keeps going after they've returned to center. Second most important take-away I got: If the nose has been allowed to wander off to the left and the pilot leaps on the right rudder in an attempt to bring the nose back to the center of the runway, all on one big movement, he will build in a tremendous amount of inertia. The nose will be moving so fast and hard that it will automatically swerve right past the centerline before he has the chance to adequately stop it with the left rudder [and in the Dora, it'll just trip over the left main gear and dump the left wingtip into the ground - Nighdrag]. A far easier method to bring the nose back to the centerline is to first stop the nose in the direction it’s heading, i.e., it has moved left, so the right rudder is jabbed just enough to stop it from moving any further left. Then the right rudder is jabbed again to bring the nose back parallel to the centerline so you aren’t headed toward that bunch of freshly painted Lear Jets. This second piece of advice clicked with me and allows me to save even the worst takeoffs and landings. If I'm coming off runway centerline really bad, I don't hold rudder until nose tracks back to center in one movement. I jab the rudder and then get off of it to first line up parallel to the centerline, let the Dora settle, then jab again to get the nose to the right and drift back to center, then little jab left to take the correction out as I drift back over the centerline. So it's a 3 step process, and not 1 control movement to come back to center. Trying to swing the nose to return to centerline at speed causes the Dora to dump over on the wingtip, especially when fast enough for the tail to be light. The original article link is here, and I hope it "clicks" for others struggling as it did for me: http://www.aerodynamicaviation.com/documents/Taming.pdf. [Or use your favorite search engine for the article "Taming the Taildragger pilot" ] Also - another tip: use the mission editor to reduce your fuel-load below 40% for takeoff practices. It empties the rear tank, and makes the Dora more responsive and less prone to tip over the mains with rudder. It takes off easily at as low as 2400 RPM, so torque effects aren't as bad. Once I mastered that, I went to 100% fuel, and 2800+ RPM takeoffs.

Revisiting this after a few weeks away. The left wing dip as the tail comes up is what is getting me. I don't see it in the P-51, that thing lifts off real easy. Most everyone who is not having problems, including the manual says nothing about aileron. I need right aileron every time to keep the left wing from dipping down as the tail comes up. It's become as important as the rudder for my takeoffs. The other thing I'm noticing is that everyone says the tail should come up at 175kph, I'm hearing the screech of the tailwheel or mains begin bouncing well under 150 kph, as low as 120kph with full power, and confirmed in external playbacks. When the tail comes up under 150kph is when things go bad very quickly. Anything less than 1/3 rudder deflection is not enough to maintain runway centerline, but the tailwheel has no traction, and isn't helping. If I can't get airborne before I drift off the runway, the left main sticks, and then the left wing dips and the Dora cartwheels. Stabbing the rudder more than about 1/3 deflection and the nose comes to the right like I need it to, but the Dora trips over its own left main gear, and the left wing drops anyway. Sometimes this is survivable and right aileron can get it level. I also have bad outcomes steering with rudder only and a locked tailwheel. As I reason it, the locked tailwheel dampens the effect of both torque AND rudder. Thus, while the tailwheel is locked, I have to put in A LOT of rudder to have any effect. Once the tailwheel gets light and loses traction, this heavily deflected rudder suddenly comes into play, and as stated above, the nose steers(hard!) right, and the Dora trips over its own left main, and drags the left wingtip -- unless I'm on the ailerons. So basic question -- is anyone out there taking off in the Dora without some noticeable amount of right aileron?

Turning off takeoff assist certainly allows better control authority, and having it down to 0% helped responsiveness immensely. That left wing often dips though, and gives me a feeling akin to carrier take-offs: that scary low dip toward impending disaster, then enough airspeed builds and the airframe rises back up to a successful takeoff. I did some high speed taxi practice with the Dora, S-ing down the runway, to figure out where this rolling tendency was coming from, and noticed the Dora handles differently if steered with rudder versus brakes. Once fast enough for the tail to get light, the Dora, as modeled, feels like a vehicle with a very high CG (e.g. a double decker bus). If I use rudder only, the Dora has a strong tendency to tip over on the outside main gear and drag the wingtip on the outside of the turn. This is especially acute with right rudder and high power settings (takeoff situation). However, if I use the brakes, the plane pivots about the braked wheel, and I can S back and forth wildly, and groundloops are generally flat, wings level.

Add me to the list of folks having trouble lifting off in the Dora. The P-51 is a piece of cake by comparison. What's getting me is a very hard roll to the left as the tail gets light. Sometimes I can counter with aileron, but sometimes with the stick full right, the left wing still rocks down, digs in, and then I'm cartwheeling along the runway. The P-51 model by comparison had no tendency for hard uncommanded rolls during full power takeoff runs, just nose-left yaw, easily countered with rudder alone. I've had the control-indicator (CTRL-ENTER) display up, and I've verified it's not the controls commanding a left roll. I experimented a bit with slow-flight at airspeeds betwen 280-240kph, and I noticed that at low speeds, engine power introduces a significant roll moment on the Dora. High power settings, and the Dora rolls left. Idle power, and the Dora rolls right (implies an aerodynamic bias to counter the engine). Above 300kph, and the effect is significantly muted. Several posts indicate using a neutral stick and letting the Dora come up. I haven't successfully taken off like that yet, all my successful takeoffs have had both right rudder and right aileron to keep the airplane wings level, tracking down the runway centerline. Maybe it would help if I understood the phenomenon behind the left-rolling tendency in the FW-190. It seems like those having an easy time never mention it, so I'm wondering if I'm doing something to cause it, or getting myself in a situaton where I can't handle it (i.e getting the tail up before the ailerons are effective).