1/24 scale DH Mosquito for rubber power.

[Prosper]

This is my winter project. I started it weeks ago - months, maybe: about the time that Bruce's HPA went dark.

I have now finished 'Phase 1' - the construction of a crude proof-of-concept model, and flight thereof. It's the last bit that's taken ages - mostly just one flight before wind, rain, dark or cattle stopped me, then many days before the next chance. The model could appear to want to fly, then next flight, days later, would collapse in a heap and look like it could never fly. I got a couple of approx 20 second flights, but wanted another one or two, preferably on camera, to convince me to proceed to 'Phase 2' - a properly-constructed and finished scale model. At last I have achieved several flights over the last 3-4 days, and I'm now [almost] convinced to go ahead.

The actual build of this test model was surprisingly quick, especially given the huge amount of research needed to get the shape right. More of that later.

The video,  https://youtu.be/nBDo7I6QxFM

shows seven flights over the last 3-4 days. Well - most of them are not flights, really, just crashes. I've just glued them end-to-end with no text on screen, so I'll describe them here.

1) Oops - I noticed a broken strand in the right motor while winding, but thought I might get away with it . . . err, no. You might spot the right nacelle breaking away on 'landing': that's normal.

2) The model has almost zero 'decalage' and it doesn't care whether it keeps going up . . . or keeps coming down. Perplexingly it also demonstrates good stall recovery at other times.

3)Worried by the proximity of cattle and wanting to keep 'em in sight, I didn't gauge the breeze carefully enough and launched downwind. The model didn't achieve climb-speed.

The remaining flights are all from today.

4) What was that? It's way too pitch-sensitive. I need to add noseweight but I'm too miserly.

5) See? That's what adding a tiny bit of down-elevator gets you . . .

6) Hey - it flies! (Sort of.)

7) Hey - it flies for more than twenty seconds! (Sort of.)

The still images attached are 1) A screenshot taken from video flight 6, when it happens to be straight-and-level for an unusually long time . . .about 0.14 seconds . . .

2;3) The model after the last flight. The last picture is an art-study, entitled 'Picture of Mossie with Moo-Cows'.

Those cattle have been really annoying. They're young, bored, and hungry. Any activity on the field gets them ready for a stampede. I could only fly today because the farmer had just spread hay on the field and they're too busy eating to worry about destroying model aeroplanes.

Stephen.

[Squirrelnet]

Wow what a great project Stephen. Looks like it's making good progress too from the video

[OZPAF]

That looks like a challenge to get flying, Stephen. I would imagine that twin rubber powered models would be a hand full. Two motors of slightly different power deliveries with two large props upsetting stability - definitely fun.

Young hungry cows - hope they are friendly.

John

[AndyB]

That first picture brought me up short - I rather like it.

Very impressed that you're having a go at a Mossie; I had a NoCal Mosquito that I managed to get exactly (numbering from the left) one good, circling flight out of. All the others were all over the place, it had a mind of its own. I eventually came to the conclusion that it had not enough tail area and too much camber. I still have the props and motor sticks somewhere, your efforts are inspiring me to have another go at it.

Andy

[Prosper]

Hullo fellows - good to see the familiar names convening again.

I have to say I don't have a clue regarding the trim of the model - like John says, I believe the power output of the motors will be slightly different, and what's more continuously varying as clumps of rubber break up, or brush the nacelle structure. The whole tail is completely blanketed by the slipstream. The sharply-tapered wingtips will want to stall (no washout). To my mind the CG looks adequately forward - but with the couple of degrees of down-elevator indicated, the wing and tail have almost the same incidence.

The reason I'm prepared to push things further is that I made a Westland Whirlwind years ago that behaved in a sedate manner. It occurs to me though that the Whirlwind had a high-set tailplane . . . might make a big difference if it's out of the propwash . . .

Yes the heifers are very friendly - but boisterous, and they'll test anything new by snuffling and licking and nibbling it - including model aeroplanes.

Andy, since I had no part in the composition of that photo - it just came about by pure happenstance - I think I can say that I like it too, without sounding conceited. The winter sun, the silhouette, the stark winter trees . . .  I hope you resurrect your NoCal model.

Stephen.

[MKelly]

Great project Stephen, look forward to reading about the construction techniques you've used on this one.  Are the ailerons pendulum-controlled or simply adjustable?

Mike

[Prosper]

Yes, pendulum ailerons, Mike. I think they're responsible for the wing-rocking when the model is hovering on the stall. There's probably a tip-stall and the ailerons correct, then maybe some hysteresis-type overcorrection. I have a non-scale pendulum model I made for an article in Aeromodeller Magazine, and after adjusting the pendulum setup (can't remember what I did), it flew whole flights with the wings rocking, even tho' nowhere near stalling. Kind of cute, but not very scale-looking. Pilots waggle their wings to say hullo or goodbye or whatever, but not for the whole flight! (Well, except me when I was a student, probably.)

FWIW here's a  video   from 10yrs ago (can't believe it ) of my Whirlwind, flying like wot a lady oughter. It was bigger than this Mosquito.

I opted to make a Mosquito test model because for me, a Mosquito was just too speculative a venture to merit a detailed, finished model from the outset. Those sharply-tapered wings; almost no dihedral; all that mass hung out on the wings creating loads of roll inertia . . . for the same reason I didn't intend to start a Mosquito thread on HPA unless and until it had flown more than say, 15 seconds, and looked capable of more.

But apart from proving basic viability, a huge advantage of a test model is that it can be flown over hard and rough ground even when untrimmed. Who cares?. All the flights of this model have been over hard-frozen or just slightly thawing ground. I'm pleased that my initial concerns over the design's ruggedness have been amply dismissed, with the cavorting model hitting hard, including one treestrike: a very low branch from which the model fell to ground. Sometimes a nacelle detaches on landing - the means of pinning them in place being very clumsy and 'afterthought' on this model. Another big worry was whether the prop blades would withstand landings. Again, yes - to my mild surprise and great relief. There has been one broken blade - in fact on flight no.3 in the video, when I launched downwind and the model accelerated onto the ground. The broken blade was the first thing to contact the ground. Luckily it snapped in a way leaving a large surface area for re-gluing and the repair took a minute or two with thin CA. See the blade lying on the worktop in the attached image.

Stephen.

[Lastwoodsman]

DeHavilland Mosquito

Sun Jan 11 2026  10:00 AM  local time here in Windsor, Ontario, Canada.

    Hi Prosper Stephen!  Thanks so much for those videos -  it was great action there.  It is good to see those FF rubber trimming videos.   

    In Pic #1,  I also see about 30 blackbirds,  maybe  European "Rooks"  or  Crows (?),  content to witness those entertaining flights,  whilst sitting atop those leafless trees.

    Yes,  those cows do look menacing ....

Lastwoodsman
Richard

[OZPAF]

I think you are correct about the more efficient high mounted tail of the Whirlwind. A larger tail would certainly help but would possibly need to be much larger than scale.

A thought though - what if the tail is enlarged slightly and set at a positive angle to the fuse centre line with the wing slightly more positive - the idea being to have the tail flying a little higher above the wing wake with it's nacelles etc.

A quick test with a profile model may prove whether this is worthwhile attempting in more detail.

By the way that's a nifty freewheel setup on your prop!

Good luck.

John

[Mark.]

Having still got my 40" span Mosquito, I can confirm that a larger tail does indeed help them to fly, but they still remain knife edge.

I added some very crude additions to increase the tailplane and tail fin area, to prove it was worthwhile perusing. That was around May 2025. It was a great success, so I made new larger tail surfaces, and even managed to make them lighter than the originals! It was so close to finally being trimmed last year, but it ended up sustaining damage (again!), got repaired and it's been sat waiting for trimming again because the weather in 2025 just wasn't in free flights favour.

Funny thing though, I've seen my Mosquito display the same characteristics in the air as your 1/24 version, despite mine not having working ailerons!

Got some better propeller blades as well for 2026, but they can wait until it's trimmed. Assume you're running counter rotating props as well?

[Prosper]

Hi Richard, good to hear from you. Those birds - had they been birds - could well have been rooks, though more likely jackdaws. However in fact the shapes are the remains of the flowers or seed pods of the ash tree. They cling on all winter, it seems. I will keep an eye out to see when they drop - Spring, I expect.

John's and Mark's talk of enlarged tailplanes has got me scared. I'm not sure I could face that. First of all when weather and cattle allow I'm going right thru the repertoire of downthrust v. elevator; noseweight, and prop-pitch changes too, perhaps. On the face of it the tailplane is a good size - nearly 19% of wing area, which is what Monty Python would have called "lookshury". It's decently thin (about 10% thickness to root chord) and looks a decent shape in terms of efficiency.

set at a positive angle to the fuse centre line with the wing slightly more positive - the idea being to have the tail flying a little higher above the wing wake with it's nacelles etc.

I see what you mean John. I'm not sure that the tail could be raised a worthwhile amount without the fus. taking on a ludicrous flight attitude (and adding lots of drag). However, I don't know - perhaps only a small adjustment would 'make the difference'.

I've seen my Mosquito display the same characteristics in the air as your 1/24 version, despite mine not having working ailerons!

That's interesting Mark. Maybe it's just the inertia of the heavy nacelles then. Even absent dihedral, there is a roll-damping effect - the downgoing wing has a greater effective angle of attack, and so more lift, and obviously the reverse for the upgoing wing.

No, both props rotate clockwise. There is lots of torque, which thus far I've controlled by a fair bit of downthrust in the right prop. This trick I remember learning from Tom Arnold - he mentioned it donkey-years ago on HPA and I didn't forget despite not ever using it. As I recall the Whirlwind needed no thrustline adjustments.

Stephen.

[dputt7]

    Hi Stephen,
                Another Beautifully made model as expected. Just to add to your list I've always found 50 or so extra winds on the outboard motor gives a twin a positive path to fly, Just a thought.
                       Dave

[Prosper]

Thanks Dave, that's a good tip. Now that the model seems to be behaving, to some extent (see below), I'll try that.

I've made some progress . First, lots of downthrust on both props. Second, noseweight - an arbitrary 4.5g, which happens to be the weight of a little slab of lead I found, and stuck under the nose with carpet tape. A couple of short flights indicated an improvement, tho' it was too breezy to be sure. So this morning in dead air I wound about half turns and the model climbed well and made its first steady orbit. Then with nearly full turns and with camera, the model made a much wider left-hand tour, thankfully just staying within the field boundary.

Vexingly, the video didn't 'come out'. It's really hard to hold the camera and the model in one hand - much harder than for a single-engine, because there are two props being blocked by one's fingers and constantly trying to escape - fingers that are needed for the camera too. I must have moved the zoom lever, because the vid. was not zoomed and the model was a little scrap in the distance most of the time - and what's more blurred almost totally. At this wide angle, the autofocus didn't know whether it was meant to focus on trees, clouds, model or what.

There were just 3-4 frames with the model in focus so I've attached a pic cut from one of these frames. I guess the wider angle at least gives an idea of the height reached. In both flights the model began to stall a lot towards the end, suggesting less downthrust but more down elevator.

The second flight was 27sec. The model always lands with plenty of turns still available so I'll be trying 1/4" motors instead of the current 7/32". But for now I'm at last fully convinced that it's worth going ahead with a detailed and finished model. Man, I've got to make the tail lighter! This model doesn't even have a tailcone or tailwheel and it still needs noseweight.

Stephen.

[pedwards2932]

Great flight pics.  I use a gopro copy on a headband then once adjusted properly all I have to do is watch the model in flight and it pretty much stays in the focal frame.  It might look a bit ridiculous, but it seems to work.

[OZPAF]

It's good to hear that you have tamed the Mossie Stephen. It looks very atmospheric in that photo.

John