Fokker Dr.1 handling characteristics

[Holtzauge]

Late this summer I had the opportunity to visit Mikael Carlson's airfield and see his Pfalz D.VIII in flight and also got some interesting information about the handling characteristics of his his Fokker Dr.1. This is now a part of a larger analysis about turn performance that can be found here but I thought I will post it here as well since there is always a lot of talk about the handling of the different aircraft here in-game in FC so it would be interesting to hear forum input on this.

 

As you can see, the Dr.1 we have modeled in the game compares very well with what Mikael has to say on  most points. I'm sure  @Chill31 will be able to add even more info on the handling when he has tested his new upgraded Dr.1 with the new Le Rhone engine but to begin with, below is the info I got from Mikael:

 

 

" The author has had the good fortune to speak to the Swedish aviator Mikael Carlson who has taken pains to build what is arguably a carbon copy of a Fokker Dr.1 accurate down to the last nuts and bolts. Not only that, but he flies it in advanced manoeuvres as well meaning he is in a unique position to talk about the Dr.1’s flying characteristics since this is not a replica but an actual reincarnation of the plane built and flown as it was in WW1.

 

Mr. Carlson’s Dr.1 is also authentic in terms of instrumentation meaning there are no hard numbers on stall and maximum speed available since he flies the plane as it was flown back in WW1, i.e. by feel. Concerning turns, while he has not timed them, he says there is no marked difference in turn times left or right once settled into the turn but that the gyroscopic forces do help in establishing a turn to the right while opposing a turn to the left. He also confirmed that the Dr.1 slows down rather quickly in tight turns, just as predicted in the simulations.

 

Contrary to common belief, the gyroscopic effect in the Dr.1 is quite manageable and gyroscopic forces are in fact more pronounced in a North American P-51 according to Mr. Carlson who not only flies the Mustang but also the Hangar10 operated Messerschmitt Bf 109G-6 putting him in an authoritative position to judge these airplanes relative handling characteristics. Interestingly, another airplane he has flown that exhibits pronounced gyroscopic effects is not a rotary powered plane but surprisingly enough the jet powered de Havilland Vampire with its huge radial compressor. Returning to the Dr.1’s gyroscopic precession characteristics, he said these are quite manageable unless at very low speeds close to stall and that consequently, he tends to lean a loop slightly to one side in order to have control of in which direction the Dr.1 departs should the speed become too low at the top of a loop.

 

The Dr.1’s stall characteristics are very benign according to Mr. Carlson and in fact the aircraft does not have a pronounced stall point at all but kind of mushes when exceeding the stall angle of attack while still retaining good control authority which supports the popular legend that Fokker’s thick winged Göttingen profiled Fokker Dr.1 and D.VII had the ability to hang by the propeller to catch an unwary Entente pilot from below.

 

In yaw the Dr.1 is neutral in directional stability meaning that if the pilot uses rudder to give the plane a certain yaw angle, it will stay there until the pilot actively uses the rudder again to bring it back on track lending credence to the Dr.1’s purported ability to fly sideways while firing its guns.

 

When asked about the Dr.1’s spin characteristics, Mr. Carlson said he has chosen not to explore this part of the envelope since the high rotational speeds in a spin would cause significant gyroscopic loads on the bearings of the engine which seems like a prudent precaution given how scarce and valuable the remaining original WW1-era rotary engines are.

 

A further note of interest is that he said that the aerodynamic overhang balances on the Dr.1’s control surfaces work well and there is no tendency for overbalance within the flight envelope and that the aileron stick forces remain light allowing rolling manoeuvres even at higher speeds which is in stark contrast to the aerodynamically unbalanced ailerons on the Pfalz D.VIII [ref 1] which he says are hard to budge at higher speeds.

 

Another interesting point regarding the Dr.1’s aerodynamic characteristics is that it is tail heavy and given Mr. Carlson’s quest for historic accuracy, his Dr.1 has been balanced as it flew in WW1 and the center of gravity is as far back as 32 % MAC which explains the significant down elevator needed on the Dr.1 to keep the nose down. In fact, he has equipped his Dr.1 with a bungee cord connected to the stick so that there is some level of trimming available to handle the stick forces needed to maintain the pronounced stick forward position needed to keep in level flight. With the center of gravity so far back he points out, the aircraft is basically unstable in pitch and needs to be flown pre-emptively at all times.

 

Taxiing is best done with helpers on the wings assisting in getting the aircraft in the right direction and lined up for take-of. There is however directional control available should it be needed, if the skid is unloaded and the engine gunned to get sufficient airflow over the rudder. Landing the Dr.1 should always be done as close to a three point landing as possible and into the wind using the elevator to push the tail down and get traction for the skid after touchdown. Crosswinds are to be avoided as far as possible and the plane is prone to ground looping and after touchdown some engine power and constant attention with the rudder is needed to maintain course. Attempting wheeler landings is off the table as it is an open invitation for a ground loop and consequently something he avoids doing in the Dr.1.

 

As a final note on handling characteristics, Mr. Carlson commented that pilots sometimes like to tell stories and that the Dr.1 is in fact not that difficult to fly as long as you have sufficient experience flying it. Different in the sense that other combinations of control movement are needed but as long as you are familiar with the airplane and the somewhat unorthodox engine control, it is not that much more difficult to handle than a more conventional plane. That however said with the caveat that the Fokker Dr.1 does require the pilot to handle it in the correct way and pay constant attention or, as he puts it, it will turn right back and bite you.

 

[ 1] Mr. Carlson has recently built and is currently test flying a Pfalz D.VIII replica aircraft with an original Siemens-Halske Sh.IIIa engine."

 

Edited February 9, 2021 by Holtzauge