Seagull Models De Havilland Mosquito ARF Review

Review by Gunnar Hovmark, Staff Contributor

Equipment Used:

- E-Flite Power 52 brushless motors, 590 kv

- Two HobbyWing 80A ESCs

- Spektrum AR 610 6 channel receiver

- Spektrum DX6 Transmitter

- Six Futaba S3003 servos for elevator, ailerons, rudder and flaps

- Two Spektrum A7000 retract servos

- APC 15x10E propellers

- One Gens Ace 6s, 6000mAh LiPo battery

- Y harnesses for the ailerons, flaps and ESCs

- Extension cords for the aileron servos.

- Home made Y harness for connecting the battery to both ESCs, EC5 connectors

- Covering: A few pieces of Oracover light grey

- Zinc tire weights, 230 g approx, in the nose

- Dave Brown Lite Flite wheels, 4.5 inches

- GForce propeller adapters for 6 mm motor axle

- Screws from my scrap box for the nacelles

- Some wire to extend the battery leads to the ESCs (against expert advice though)

Pros:

- You'll get a rush flying this

- it really gives people something to look at

- This is a crowd pleaser

- Looks stunning and is a thrill to fly

- It requires an experienced pilot

Cons:

- Prone to tip stall, has to be flown very carefully when you bring the speed down or pull high AoA maneuvers

Summary:

First I want to thank Joshua Bybee and Geoff Barber who have posted their knowledge and experience on how to assemble and fly the Seagull Mosquito in various Facebook groups. They were a great help.

 

I've always been a fan of the Mosquito Mk XIX night fighter, known as J30 in the Swedish air force, and when Seagull announced that they would make a Mosquito I instantly knew I wanted one. It's big and beautiful and it's quite easy to put a Mk XIX style radome on it. It comes with an olive drab / light grey paint scheme that is perfect for a J30. The plane in the pictures you see here is actually two planes, because I crashed the first one. More about that in ”Flying”. The ”Assembly” bit here is all about the second plane that has not yet been converted to a Mk XIX.

 

The Mosquito is apparently made in two versions, one with the decals already applied and a matt spray paint coat, and one just covered with glossy Oracover. My supplier Lindinger only sells the glossy version, and that suits me perfectly because I want to use my own decals.

 

 

Assembly:

The packaging is not quite up to coping with the ordeal of shipping. When I opened the box there was a crack in the canopy and a crack in the nose of the fuselage. The canopy doesn't look too bad after I put some glue on it, and the crack in the nose will eventually be covered by the radome anyway, so no problem for me. The nose could probably be fixed with a little epoxy and grey paint or a patch of grey Oracover.

 

After some reading of the manual I started to collect the parts. The Seagull Mosquito is an ARF model, so you have to choose radio gear and propulsion yourself. The Mosquito comes with motor mounts both for electric motors and for combustion engines. I did not want the challenge to make two glow engines run together, so electric power was the only choice for me.

I chose E-Flite motors because I have a couple since before and I really like them. They have a feel of quality and a nice sound, and my experience is that they can be overloaded with big propellers if necessary. What I don't like is E-Flite's propeller adapters. They are too short and the ”spinner” type nuts are difficult to tighten. I happened to find a couple of GForce propellers adapters to use instead, and I'm really happy with them. Long, strong, and nothing will ever slip out of their grip.

I have plenty of Futaba S3003 servos in various planes and they have never failed me, so whenever I need standard size servos the choice is easy.

 

I also have plenty of HobbyWing ESCs, and those also have never failed me. Same thing with Gens Ace LiPos and APC propellers, although it would be nice to have some more ”scale” looking propellers. For landing gear servos I looked around in my favorite web shops (all Swedish) and decided that Spektrum's A7000 would fit nicely. The hunt for wheels was a special matter. I have broken Seagull wheels before and I don't trust them. The wheels in the box also looked too small to be ”scale” on the Mosquito. I needed bigger wheels that were slim enough to fit between the landing gear struts. Dave Brown Lite Flite wheels were just about the only ones that fit the description. Fortunately they seem to be of very good quality.

 

The assembly is mostly easy and straightforward if you follow the manual. The control horns all look the same at first glance, but they are different, so make sure you know where each of them fits before you start gluing them in place.  I don't know what glue Seagull is using for joining the plywood parts, but I know it can't be fully trusted. Therefore I added some slow curing epoxy on the former that holds the tail wheel, and all joints in the plywood nacelles for the motors. On second thought I also added some epoxy to the retract servo fittings. I also had to cut the covering open and add a little epoxy to keep the vertical tail firmly in place, but I sincerely hope that it was an exception. After I had glued the tail in place I covered the gaps between tail and fuselage with grey Oracover. Not necessary, but neat.

 

The plywood nacelles are fastened in the wings with two big screws each. The manual doesn't say if you're supposed to also use glue, but I decided to use epoxy as a complement to the screws. So far I'm happy with that. To get the right nacelle shape there are fiberglass nacelles that go over the plywod. The screws that are supplied by Seagull to fasten them are big and ugly, so I looked around in my scrap box to find something more suitable. I chose servo screws for the lower parts and some black screws from an old motor mount for the leading edge and the upper surface.

 

The only part of the assembly that's a bit tricky is to get the motors aligned with the fiberglass nacelles. That took a bit of fiddling, and you may have a better method than I have. Fortunately my chosen propeller adapters were so long that when I put a spinner close to the tip of the propeller adapter I could hold the spinner and insert the motor into the nacelle all the way into the rear stop of the plywood mount and check that the spinner was aligned with the nacelle. With a little paint on the back of the metal motor mount I could make marks on the plywood so I could see where to drill the holes. (Did that make any sense to you?) I used Loctite thread lock on all motor screws and used plenty of slow curing epoxy to keep the plywood motor mount in place.

The Mosquito needs weight in the nose to balance correctly, so it's a good idea to place all equipment as far forward as possible, especially the battery. I made a battery holder out of some plywood and velcro. The ”guns” in the nose are supposed to be fastened in a plywood support in the fuselage, but I sawed most of that off so I could put the battery holder all the way forward into the nose. I'm sure the guns could somehow be glued to my battery holder, but since I'm going to build a radome I don't have to bother with that. In addition to the battery I also have approximately 230 grams of zinc tire balancing weights inside the nose.

I had to raise the cockpit floor quite a bit to make room for the battery, so I also had to cut off most of the pilot's legs and seat to make everything fit. Doesn't look too bad from the outside anyway.

 

There is one elevator servo, but it connects to two pushrods via a little piece of metal with three screws. Using thread lock there is strongly recommended. I glued the plastic cover over the tail wheel assembly with UHU Por. It sticks, but can be pried open without damage if necessary. I also used UHU Por for the canopy. The manual recommends that you put the ESCs in the fuselage, but there is more room for them and better cooling in the nacelles. Experts advise against extending the wires from the battery to the ESC, but I did it anyway. I have made longer extensions in other planes and it has worked fine so far.

One important thing that Geoff Barber taught me: When you have two ESCs with BECs (i.e. ”battery elimination circuits”) connected via a Y-harness, only one of the BECs should provide power to the receiver. The way to achieve that is to disconnect the red wire from one of the BECs.

 

You can find a really good instruction for how to do it here: https://youtu.be/F70Kr9w4sj0 . (Of course I had to try it out myself. What happened when I didn't disconnect the power from one BEC was at first that everything worked perfectly anyway, but then suddenly one day the ESCs wouldn't arm, the leads from the Y-harness to the BECs got very warm and something began to smell funny. So I took Geoff's advice and now everything works.)

 

Balancing the plane to put the CG in the proper position must be done with the gear retracted. The most important thing taught by Joshua Bybee: The manual says that the CG should be placed at 150 mm from the leading edge. That may be good for a fuel powered plane with empty tanks, because when they are filled with fuel the CG will move forward. However, on an electric powered plane the CG must be placed further forward from the beginning. I've put it at 130 mm from the leading edge and I feel very comfortable with that. According to my bathroom scale the Mosquito weighs 7.4 kg complete with battery.

.

Flying:

I have now made eleven flights with the Seagull Mosquito. My first flight was perfect, but the second ended with a crash that left my first Mosquito beyond repair. I blame the crash on three things, but I'd say the main thing was that I had chosen too small propellers. This is the biggest and heaviest plane I have ever flown, and I underestimated how much thrust it requires for a safe climbout after takeoff. The 13x10 propellers I had then were not enough, and combined with the other two things, my slightly too steep climb and the Mosquito's tendency to tip stall, things went very wrong. It stalled over the left wing, tumbled down wind and was smashed to pieces. The first flight had however encouraged me enough to order a new plane as soon as Lindinger got a new batch from Seagull. My switch to 15x10 propellers on the second plane makes me feel much greater confidence in the Mosquito's climbing ability. The tendency to tip stall is still there, but it's easier to avoid when you have plenty of thrust.

I haven't explored how long the Mosquito will fly on my 6S 6000mAh battery, but I've set the timer on my transmitter to five minutes and that seems to work. I've rarely flown on more than 75% power except during takeoff and for entering loops and rolls. I've also rarely gone below 50% power in level flight, and level turns with as little as 50% power are not recommended, you need more power for that. (Depending on what propulsion system you have installed of course.)

 

To make turns look nice you need a little rudder input, but pure aileron turns don't look too bad. When it comes to aerobatics all I've tried so far is a few loops and rolls. Make sure you have plenty of altitude when you begin with that, because high G loads with high AoA may bring surprises. Retracting the landing gear changes the flying characteristics very little, although I think I can feel that it moves the CG backwards a little. I can't notice any trim change when I extend the flaps. I still need plenty of space to land the Mosquito, as I turn on to the final high up and keep the speed up until I'm ready for the flare. You can see in the video I have linked to below what it looks like. I'll lower the altitude and speed as I get to know the plane better.

 

Conclusion:

If you have flown foamie warbirds and feel confident with that, then this is a suitable challenge for you. Make sure that you have plenty of power and explore low speed/high AoA flight gradually. You'll love the sight of this plane zooming across the sky.

 

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