Seagull Mosquito weight

[Chris Freeman 3]

We finally got around to flying the Mosquito on Saturday, it was a cold and quite windy day but the wind was down the main runway. As I assembled the plane for Greg he did the flying, this was his first scale model and first twin experience. The motors have had 3 tanks of fuel through them so they are still tight but were running well so it was time to do final checks and fly. The ailerons were a little up, lined up with the top of the tip trailing edge, and the flaps a little down, lined up with the lower trailing edge of the nacelle. I had trimmed the elevator a little down as it is easier to hold up than down.

The take off was not down the runway, had a 45% swing to the left, lucky we had lots of open space, climb out was good. We had to take out the down trim and add some left aileron and that was all the trim needed. Power was around 2/3rd throttle and still plenty of performance. Greg did a few circuits and tried the flaps and said that they caused quite a pitch up but I think that it was too fast with too much power. All to soon it was time to land and it was rather an anti climax with a straight in approach with a good touch down. Greg had used a little flap and the plane had seemed stable enough on the approach. I had used the control throws discussed here and Greg said the plane was very stable and a little mild on the controls. I have seen how he likes to fly his Stick and the movement on the controls so I am sure the Mosquito will be responsive to most pilots. Greg did say the plane might be a little nose heavy as the elevator was soft.

We had a second flight and the motors were not as happy as the first flight, seemed a little rich on the bottom end. Take off was still 45% to the left, rudder is very poor to correct, throttle application could be a little slower. Wheels retracted this flight, I forgot to switch on the power for the first flight as I have the retract servos on a separate battery. Looks much better with the wheels up but Greg said it was not much difference in the air. Greg did a few passes and this aircraft is very fast with the ASP 52,s with 11x7 props. Greg then took it up and slowed it down a bit but did not push too much and then gained speed and rolled inverted to check the CG. He said it was not bad inverted but then one motor quit. He rolled out and turned down wind and then turned to line up with the runway and landed. He had to use power to make the runway and said it needed about 1/2 the rudder movement and 1/3 aileron to fly straight. Landing was not perfect and nosed over at the end on the landing roll out but no damage. I have not yet added the guns or the aerial as these bits will cause more damage in a situation so they will be added when we are more used to the aircraft.

Greg has now got his twin rating and single engine rating all in 2 flights! I was very pleased with the way the Mosquito fly's and think that the forum members have got there information correct for the set up right. Thanks for the help guys.

Chris

[Chris Walby]

Chris,

Thanks for the very informative descriptions of flight and ground performance its very useful to know what its likely to do and be prepared. I had not fully considered the substantial swing as the Dual Ace is totally benign even if I slam the throttles wide open (ground runs only, as I follow manufactures recommendation and take off on 3/4 throttle).

I have a couple of warbirds that swing although rudder deals with it adequately and the pits fence will prevent any off runway excursion on a northerly take off.

I hope you resolve your inverted running issue, what do you think the problem is?

[Chris Freeman 3]

The motors are new so they are still running in and need to be a little leaner on the bottom end. The one motor is also very tight so it might be getting a little hot. The carp position is also not ideal for our very dusty conditions at the moment as we fly of a grass runway as winter is finishing and we only get rain in summer. I am sure that the motors will be fine but at least the Mosquito can fly on one motor given the right conditions, would not like a dead motor just after take off. Vibration also is a concern on a twin, especially with higher revving 2 strokes. Using master airscrew wood 11x 7 props

[Chris Freeman 3]

Confirmation of flight

[Ronos]

Nice one Chris, thanks for the in insight on your maiden and second flight. The lean to the left is one to watch for, especially with the rudder behind so benign.

[Jon H]

to help out with the swing try some different props. 12x6 would probably be better suited to the model anyway and may give less swing. Another thing is that if one engine is a little slow accelerating this could, and most likely is, causing the problem. nail down all your tuning and slowly apply power. I am always very slow getting the power on with a twin. I usually do just enough to get it rolling, then coax the tail up, then add more....it looks cool and covers off an engine bogging down.

Also, nice job proving that loosing an engine on a twin is not the non recoverable disaster it is often claimed to be

[Chris Freeman 3]

I agree with you Jon, 12 x 6 will help slow it down and better acceleration, I was just pleased to see it fly as one of our local importers and quite a hot shot pilot crashed one on the first flight. A scale warbird needs to be set up correctly with control throws to the minimum not the maximum. Very hard to get a twitchy aircraft to look realistic in flight.

[Jon H]

I couldn't agree more. Warbirds aren't difficult to fly but they are different and require a very specific style of flight. They really don't appreciate being slapped about the sky. Its more about being smooth and flowing. Just nudge the model where you want it to go.

Alas its sometimes easier said than done as the learning curve is usually pretty steep and often its all over before a new warbird pilot has realised they made a mistake.

The more I see posts and comments about this model the more I am tempted to get one. My current sport twin is ok, but its not really setting my world alight. I could take the two Laser 70's out of it, along with the radio, and be up and running pretty quickly.

Might have to have a clear out and see how the finances look...not to mention the space!

[Chris Walby]

Ronos, gentle bump to see how you are getting on?

Hope you are all set for the maiden, any questions please ask.

[Ronos]

Hi Chris sorry about the delay. No maiden yet, weather and work are getting in the way. Can you tell me what the reaction was when you lowered the undercarriage, was it very nose heavy? The reason I ask is, balancing with the retracts up, slightly nose heavy, lower the retracts and it tips over with a vengeance. I know a model will tip over with the retracts down, but this seems a bit aggressive. Yours didn't look to bad in the video so was just wondering?

[Chris Walby]

Ronos,

From memory the C of G only moved a few mm between gear up and down and in the right direction (gear down C of G forwards. Plus remember forwards is good, I have an foam EDF that moves rewards by 35mm and is a right mare when it does it!

The other thing to remember is the C of G will be further forwards with the fuel in, I flew and landed and used 3/4 of a tank full.

It didn't seem to pitch down much with the gear or up with flaps at half although it did seem to add quite a lot of drag + aileron response seemed to be affected (low rates), but then again it was a down wind turn into wind and could have caught some turbulence. I landed without flaps and it was really tame into the head wind. Seemed very controllable with the low rate elevator movement and sat nicely (the Dual Ace holds off and then just lets go and plonks down). Lastly our grass is short, but even running into the longer grass it didn't tip over.

Might be worth being ready with the throttle cut if the tick over is high, no head wind and you are running out of runway.

PS my engines came out of the Dual Ace so they were just about run in and nicely set up (although I have never adjusted the low end.... if it isn't broke don't fix it!).

For me its about reducing the risk of an issue and being ready with plan B should something happen. Don't fly unless you are 100% happy the engines.

PPS I assume you are using the 130mm C of G position?

[Ronos]

Chris
Yeah using the 130mm c of g, the mossie was up on the CG stand with empty tanks, probably will just have to wait and see what's its like when I get it up. Can you tell me you set your control surfaces to.

[Ronos]

Well got round to maiden her yesterday,and she did exactly what has been already posted. Into the wind about 6/7 knots, bit of right rudder to keep her straight, up she went. I put three set of D/R and Expo in the TX.

Aileron- Curve 0 D/R 100% Expo 25% Curve 1 D/R 60% Expo 40% Curve 2 D/R 40% Expo 40% Elevator Curve 0 D/R 100% Expo 40% Curve 1 D/R 60% Expo 40% Curve 2 D/R 30% Expo 25% Rudder- Left all on 100% On take off had aileron on Curve 1, Elevator on the same. Got her to a safe altitude and turned into the wind, dropped down to 3/4 throttle lifted the retracts , a good bit of up elevator touch of left aileron and she was good to go. I kept the aileron on curve 1 but dropped the elevator to curve 2, found this a lot better for turning as I use the ailerons to turn rather than the rudder and found it doesn't need much elevator to alter the pitch. Done a couple of laps then turned her into the wind for a landing. Full flaps, gear down, a bit of climb eased of the throttle she began to come down. We have a fence around our site about 4ft high and once clear of the fence you have to be quick to get it down, and with the weight she was coming in fast, ok if you have a long strip but not so good if your limited, anyway got her down on the ground, and must admit something on my body was twitching. It was a bit of a hard landing nosed over and dug in but no damage, but I was pleased she was back safe. Sorry no pictures and no one was there to witness it as I was on my own.

[Nigel Banham]

Hi Everyone, My thanks for all the info re CG and throws/settings etc. I have gone the electric route, which is a little against the grain for me, but two guys in our club, John Ranson and Tony Waters, have built and successfully flown beautiful, larger electric Mossies - (with sound systems as well) and I picked their brains. To help the CG issue, I built a tray for my two 6sx4500 lipos, right at the front of the fus and then had to fit capacitors as Danny Fenton did. I have also moved those two fuselage servos as far forward as poss and used pull-pull wires on the rudder and the "mighty" tail-wheel, to get rid of two of those long rods. The Rx is in the port nacelle with its separate nimh battery and the retract battery - a small nimh is in the starboard one. The switches for both are on the outboard side of the nacelles under the wing, together with their charging ports. Both batteries as far fwd as poss under the wooden inner nacelles.The CG has actually come out at 122mm back from the LE at the root which is probably too far forward so should I take it back to 130mm which is where you guys seem to be setting it with success?

I believe that Seagull must have designed for IC because it seemed that both nacelles had quite a lot of right thrust. I have fitted a "pusher" prop on the starboard motor, so that gets rid of the torque problem as the props go opposite ways. Yes - I know that this is not "scale" as the original had them turning the same way but I'll bet that the pilots would have loved to get rid of that swing on take off! Props are 16x10 electric and they turn at 7300, which gives quite a decent wind. A little butchery was needed on the outside nacelles as the right thrust was also evident on them. I have tried to get the both at zero side thrust with just a little down-thrust.

Anther thing that I have discovered whilst doing this "build" is that the Oracover (fuelproof) two pack paint , which is a reasonable colour match, is an "Ouch" very shiny gloss paint, so I have some flatting down to do on all the bits that I have painted.

Now working up to the maiden - I would stick some pics of my changes on here but I have not used this forum for a few years and have forgotten how to add them!

[Stearman65]

Posted by Nigel Banham on 05/03/2019 08:31:57:

I have not used this forum for a few years and have forgotten how to add them!

If you haven't already, click on the albums tab at the top & import your pictures into the album, 5 ata a time. Then go back to your post, click the camera icon & copy them into your post., easier than flying a Mossie!

[Chris Walby]

Hi Nigel.

All the best of luck with your Mosquito, If it was me I would keep the C of G at 130 or you might find the landing a bit fast (although mine is over weight it seemed to float in to the decent breeze with no flaps - DO NOT DO THIS).

Having buried my BH Mosquito (tip stall when landing) IMHO I think there is a significant tendency to fly too slow and not appreciate the drag from flaps, gear and props (my undoing).

With IC I tend to fly the approach under power so I can hear the engines and come in thus quite quick (of course once I master flaps I can do a proper approach!) get over the runway threshold and settle her down. If you are too long just go around again.

With the electric I tend to cut and glide it or reduce power (this is a really bad idea with a high drag set up e.g.flaps/gear and three bladed props) and warbird type model. It will bite, but only the once.

PS - might be worth making sure your electric set up will run a couple of minutes at full throttle and then a couple at 1/2 throttle to make sure you don't get an ESC/motor failure (been there had that with No 2 BH mosquito, and just got away with it - more luck than skill).

All the best, Chris

[Nigel Banham]

Hi Chris,

Thanks for the advice on flying and testing. I will take the CG back to 130mm - not too hard to do!

Flying too slowly on the approach is a killer. I used to have a Brian Taylor Tempest that virtually stopped when the flaps were lowered. You had to keep the nose down and flare at the very last moment. I will perhaps try a "landing " at height first just to see what the stall is like!

I didn't put down the AUW - it is 7.366 K, which seems to be about the same as everyone's ...and I have been trying to upload the pics and failed!

I doubt that I will fly it this week - it is blowing old boots in Suffolk and I will wait till it settles. My thanks for your help.

Kind regards,

Nigel

[Chris Walby]

Nigel,If you have experienced what flaps can do I am sure you will be ok, for me its the combination of draggy bits and the power required to counteract it (the BH Mosquito is close to 40% power just to hold speed with everything deployed).

Looking at one video the stall seems to be quite aggressive so it might be better 4 or 5 mistakes high to give you time to get out of it. Personally I would not risk the consequence if I can't get it out in time and would go for the progressive increase in flap approach over a number of landings if you have the room.

Skip to 4 min 50sec and have a close look at how slow it will go before settling down, it did surprise me with no flaps.

**LINK**

Hope that helps, Chris

[Nigel Banham]

Hi Chris,

Yes - point taken. I did not realise that you had no flap on but the wind sounded quite brisk so in real terms you had more airspeed. Thanks for the video - You did very well and those 4 stokes sounded great.

I would imagine that with those pointy wings the stall would be nasty. Even a small amount of flap should help that because you are in effect introducing a large chunk of washout, but of course, the drag goes up. The 40% throttle needed to hold speed is interesting. Most A/c go nose up when flaps are deployed - at least until the speed decays, but a few go tail high! What does the Mossie do? I think that I am going to get the club test pilot to do this one. He is a better pilot than any of us and is about 30 years younger than I am!

Kind regards,

Nigel

[Chris Walby]

Both gear and flaps at 1/2 didn't seem to make a lot of difference to pitch from memory. The only thing I didn't like (as I was on low rates) was the down wind turn into wind with flaps at 1/2 as I seemed to lose aileron authority.

Most likely a combination of turning too tight, being too far away and rushing the approach, anyway I didn't need to risk a flap approach with that wind and a long runway so went around and did a non flap approach on to the long runway. I can't say I was happy with my technique, but if I was too fast I would just go around and have another go!

My point is that I come in quite fast and the interesting bit for me is how slow and gentle it settles down. Now if I can sort out a flap approach then I will be happy with shorter runways.

Summary, nice model makes up for poor piloting skills(mine). If you have flown warbirds (reasonable size) with flaps I don't think you will have any issues.

In comparison to my Dual Ace the mosquito has a fatter more cambered wing so produces more lift as long as you don't stall it! you should be okay.

And before you ask I would won't try spinning the Dual Ace either! The technical guys might be able answer the question "for the same length wing with the same washout, same wing loading, but different chord at their respective stall is one more abrupt than the other?"

[Danny Fenton]

Welcome back Nigel, glad to hear you have tackled the Mossie.

Once the c of g issue was sorted mine flew really well, no flicking or anything nasty, even the takeoff with both props turning the same way was a non event and it hardly swung.

As Chris says, don't cut the power fly it down and you will be fine.

I am looking forward to flying mine some more this year, maybe we should get them all out at Greenacres or Buckminster

Anyway good luck with the maiden, I am sure you will be fine, and we want a full report

Cheers

Danny

[Nigel Banham]

Thanks for the advice guys - I will let you know how I get on. Keep the speed up is a good mantra. Got it! Sadly, I watched a lovely scale model get damaged last week due to slowing up the approach too much. Speed does not wreck aircraft; it is the lack of it.

The idea of flying a lot of Mossies together at an event is an interesting exercise, particularly if they all have the same markings! Now - I have some dayglo paint somewhere....

All the best, Nigel

[Jon H]

I agree with Danny on the engine front. Counter rotating props are really not important as the power/weight ratio of our models is so high, and acceleration so rapid we end up with rudder control more or less from the start. Its a little different for the full size.

For landing warbirds i always recommend a very steep approach with large amounts of flap angle and power used to control the decent. As a guide, if you normally land with a flat ish powered approach i would go at least 3 times higher and then point it at the end of the runway. If you have enough flap angle it wont accelerate much and you will probably need power to prevent coming up short.

Looks ace when you get it right though as they just parachute down.

[Nigel Banham]

Now that is interesting because that is exactly what my B.Taylor Tempest used to do. (I suspect in that case that the efficient split flaps slowed it, but it did not accelerate in a dive with flaps and on tickover, even though it was heavy. I have a large BH Chippie which has a 40cc petrol 4 stroke and although it is beautifully behaved, even with the flaps down it speeds up on tickover in a dive, so that has to be landed power on but with along flat approach - luckily we have the room to do it!

Thanks for your help

Nigel

[Jon H]

How much flap angle is on the chipmunk? less than about 45 degrees is mostly lift and little drag. The 40cc engine is also pretty big for that model so its possible that combined with perhaps a fast idle and heavy pitch on the prop. I would be using something like a 22x6 on that, i assume its the OS GF40?