Just Flight® / Aeroplane Heaven® DH-98 Mosquito

Cockpit visibility is what you would expect for a twin-engined tail-dragger of this layout. When on the ground, the windshield is a great place for meteorological observations or bird-watching. I don’t know how they ever taxied these things. The view to the sides or 45 degrees to the front is about as bad, offering a great view of the nacelles and the top of the wing. If you get off on exhaust stacks, you’ll never find a better view of them. Fortunately the seat can be easily raised to ridiculous heights in FS without having to add blocks to the rudder pedals, so the forward view can be overcome. It’s just the nature of taildraggers.

Moving on to the actual flying, this is the kind of airplane that is just fun to take for a ride! If you’re not all hung up on radio navigation and keeping the passengers from spilling their drinks, this is the kind of AC you want to be strapped into. It’s very powerful and sounds as if it is too. It’s quite manoeuvrable, considering that it weighs some twelve tons when loaded and it goes like a bat out of hell. The panel and systems are simple enough that they don’t require a lot of attention and you can just make holes in the sky. The word “fun” keeps coming to mind. There’s a pronounced buffet as you get near Vne, which it does quite easily if you’re not paying attention.

Takeoff roll is pretty exciting. This is a powerful aircraft and even when heavy it doesn’t take long to accelerate to flying speed. The tail doesn’t seem to come up until speed is pretty high and when it does, she’s ready to fly. Add back pressure and you’re away. I didn’t normally use flaps for takeoff, even when heavily loaded – it just wasn’t necessary. Runway lengths of 3,500 feet were ample for take-off at any weight with no flaps. With a notch of flaps I’m sure it would do better yet.

As with all taildraggers, you are well advised to have it pointed where you want to go and to be ready to dance on the rudder pedals when you push the throttles. A lot of rudder is needed as she begins to roll, pulling first one way from torque, then the other. It takes progressively less and less rudder as airspeed comes up and the rudder begins to bite – but still some. It’s not hard but you have to be concentrating on it to get it right. Again, cycling the FS tail-wheel lock key did not seem to make any detectable difference here.

Once off and cleaned up, it just wants to fly. Initial climb at 2,500 fpm is easy and it will hold that rate and accelerate as you climb. Even when heavily loaded, I could maintain that climb rate right up to about 22,000 feet before having to lower the nose a little. There are no supercharger controls – everything follows the throttle, and there is no supercharger speed shifting, either manual or automatic. I don’t believe that’s historically accurate, but it’s one less thing to worry about in the climb.

Leaning the mixture, of course, is critical and the band where the engines will operate effectively becomes narrower and narrower as you go higher. There are no EGT or CHT gauges to help with the leaning – the latter wouldn’t be much help in a liquid-cooled engine anyway - you have to do it pretty much by ear. Even the tachs don’t help much with that as the prop governors tend to keep them pretty stable.

The manifold pressure gauges are calibrated in psi rather than the usual inches of mercury. Full boost is only around 14 psi – one atmosphere. If that’s accurate, these are hot heavily boosted engines. Maximum RPM, by the way is only 3,000. That too is surprisingly slow, but is prop RPM and there is likely a reduction gear between engine and propeller. The turbochargers can maintain full boost right up to about 27,000 or 28,000 feet, where it begins to fall off quite quickly. Up to that point, a decent level of engine power is available as long as you’re tending to the mixture controls properly.

Odds and ends

Cruising is uneventful but not boring. The Mossie has no autopilot, so it’s a busy AC to fly on a long flight. It is very stable in roll and yaw, but is tender in pitch. The nose oscillates slowly up and down and it’s kind of difficult to hold a steady altitude. Neither pitch trim nor throttle, nor both in combination for that matter, can be used to adjust that out for more than a minute or two. One can imagine that a long flight in wartime must have been very taxing, though at least they didn’t have ATC fussing at them if their altitude varied a bit.

Sim performance was generally good with this AC, however, in FS9 I did repeatedly experience a delay in the rendering of the 2D views out the side. If it had been more than about 15 seconds since I’d last looked, it would take a few seconds before the textures would load and display. I’d see the horizon and the sky, but the visible parts of the AC would be white (or grey in some models) for a couple of seconds. This was consistent and repeatable. I’m using a reasonably high end PC with a high end graphics card, 3 + GB of RAM and running XP. I rarely see that kind of effect on any AC. That was the only such issue I saw – the sim ran smoothly and the frame rates remained good throughout even though I run with all the sliders all the way up in FS9. 

A post publication note and important update to this section is that if you are an existing owner of the Mossie there is an update for FS9 and FSX which now addresses this problem and other issues, please visit the Just Flight support section for the update. This will not affect new purchasers of the Mossie.

Manoeuvrability down low, and by that I mean anything up to about 25,000 ft, is quite good. Engine power is more than ample and the roll rate is very good. You can do most any of the standard ACM manoeuvres in the Mossie and she’ll cooperate in a standard and predictable manner. This is the fun part and you’ll love some yanking and banking. Flying nape of the earth or whatever they called it in WWII – hedge-hopping, I guess - is great fun and you get a great sense of speed. The AC is very sensitive in pitch and as long as you’re paying attention, flight at high speed and treetop level is a real thrill.

The Mosquito descends from on high at about 1,500 fpm in a more or less nose-level attitude. If you want to come down much faster, you’ll have to point the nose down and really pay attention to the airspeed. It’s slippery and wants to go fast, even with the throttles pulled right back. I planned cruise descents from 37,000 to begin 110 NM out from the destination airport. If you leave the descent too late, you’ll be coming down with a very high airspeed.

One negative feature in some of the models is the centre windshield post. Even though the Mosquito pilot seat is offset slightly to the left side of the centreline in the real AC, the 2D point of view in the sim has your eyeballs dead centre. In the models that have a windshield centre frame, that covers the runway on approach until you get fairly close. I learned to “aim” slightly to the right side of the runway, allowing me to see it and the PAPI lights during the approach. Once you get in quite close it’s no longer an issue, but is something that needs to be adapted to. It’s all the more annoying as the centreline eye-point is not historically accurate.

2D approach view

If it seems as if I’ve avoided discussing landings until last, I have, and for good reason. I mentioned earlier that I don’t get along well with tail-draggers. Usually a part of the difficulty is tracking after touchdown, but in this case it was not. In fact, the Mossie behaves very well once the wheels are on the runway. A few clicks up on the seat height so I could see over the nose and all was well. Unfortunately, I just never mastered the art of landing this thing well. It’s stable in the approach at about 130 mph (not knots). The flaps are effective and the pitch changes from flap and gear deployment are realistic and conventional. The documents say that a clean stall is about 100 knots (not mph) but no figure is given for a dirty stall. 130 mph (not knots) on approach seemed a prudent Vref. Whatever I tried, the AC just seemed to want to be done flying about five seconds before I was and my arrivals (the first bounce anyway) were rather abrupt. I never quite got the hang of it and don’t think I ever made a greaser, though did finally improve somewhat over time. I must have made 50 landings and none were the kind you’d want your old flight instructor to see. I know it’s me and you should not construe this to be criticism of the AC, which if nothing else proved to be rugged.

The package documentation is good, though some is cleverly hidden. There are very good pages that come up on the AC kneeboard under both the Checklist and Reference buttons. There is a good pdf manual with an official wartime-looking cover included. I can only criticize the manual on two points… After a standard install of all three of the software packs and much searching, I finally found the manual pdf file lurking in the third or fourth of the eight Mosquito folders that are installed in the FS9 Aircraft folder. I’m sure it is an unfortunate accident of the alphabetization of the folder names, but it seemed an unlikely place to find the manual. And the second point - - - well, there is the matter of the missing credits for the beta testers.