Tony Nijhuis 72” Mosquito – Build Log

Sorry again that the model has been destroyed, but exactly how bad is it? Mine was a wreck after an ESC died but was repaired. Can you bring yourself to post a pic?

No pics! Fuselage broken in three, port wing broken in two, both nacelles smashed, multiple fractures all over. It's in the bin now.

But that's enough about my failure; let's hear more about the successes, and don't let the speed drop too low!

Well.......

I was having some issues with trying to balance using my hobbyking balancer, and wasn't convinced that I had got it right, so decided to make a Vanessa rig.

The amended AUW is 7.4kg or 16.3lbs .... hmm.

Yes, there must be a lot of paint on that! How much weight have you got hanging in those two bags?

16.3lbs? Ouch. Be prepared for a very fast landing.

Don't panic Mr Manwaring.... Okay the Seagull should weigh 6.4Kg and mine flies nice at 7.4Kg and I know the TN is a smaller wingspan, but dare I say it.....it has flaps.

If is anything like my BH Mossie and PZ Mossie (not tried the Seagull Mossie…bottled out) the flaps are very effective as long as you use plenty of power.

15 degrees is effective, 30 degrees and I need about 45% throttle as it becomes very draggy/more lift and the great Winkle Brown could effectively hang it on its props with a full size aircraft with 45 degrees!

All I would say from my experience is not to slow up too much as it has a sting if you tip stall it.

PS what is in the plastic bags? I did end up with some nice brass prop nuts, before I was about to turn my attention to the heavy non scale tail wheel!

I have some stick on (car wheel) weights and a couple of AA batteries in the bags.

After I took the picture above I realised that I had marked the CofG incorrectly on the wing. With the correct CofG marked it needed much less.

I have heavier (all metal) retracts and some 3d printed details but apart from that it is as per plan. Must be my covering and painting methods that need perfecting.

I have my flaps set to 45 degrees on full deflection. From reading previous comments I guess this may be too much.

Geoff,

I suspect your Mossie is much like all others regarding flap performance bearing in mind that the flaps are both sides of the nacelles. This just means that the wash of the props has a greater effect (good and bad) when the flaps are deployed.

Could I suggest watching The Peoples Mosquito interview with Eric "Winkle" Brown when he talks about the first carrier landing of a twin engine aircraft. There are a few useful pointers when using full flap

• Full flap, very low air speed and lots of engine power, if one engine quits the aircraft inverts very quickly (<3 seconds). Eric did this at height with his "Boffin" as passenger
• Eric's comments about the swap to 4 bladed props to achieve very low approach speed to the carrier

Of course he had the benefit of being in the aircraft to feel the approaching stall.

I am sure others can assist, but my plan would be:

• Set no flap position 1
• Set flaps at 15 degrees position 2 - use this and see how it slows up
• Set flaps at 30 degrees position 3 - not slowing at all, try this, but watch for pitch up and get on the power/down elevator to keep the speed up
• Set flaps at 45 degrees position 4 - Okay you have missed 2 or 3 landing attempts (still flying like a bullet) and time is running out. Almost full power and try this flap position or
• Plan B - Gear up, flaps 2, come in real low and belly it in on the long grass. Might cost you a set of props but not much else.

If you only have a 3 position switch then:

• Set no flap position 1
• Set flaps at 15 degrees position 2 - use this and see how it slows up
• Set flaps at 35 degrees position 3 - not slowing at all, try this - Okay you have missed 2 or 3 landing attempts (still flying like a bullet) and time is running out. Almost full power and try this flap position or
• Plan B - Gear up, flaps 2, come in real low and belly it in on the long grass. Might cost you a set of props but not much else.

IMHO the number one thing to avoid is tip stalling it with no height and the U/C down and flaps as its high drag.

The thing about maidens I don't like is the quantity of things to do in a very short space of time.

PS if you can pick a day with a reasonable wind straight down the runway it will help with any swing on take off and much needed slowing on the way in.

Hope this helps

I have programmed the Taranis and set up all the control throws (and set the failsafe).

I have also tested the motors which are giving 875 watts of power and 57 amp draw, at full throttle (for each motor).

Nothing left to do except buy some rubber pants and go fly!

Well, all I can do is to wish you all the best. Wind forecast for my field is fairly strong but in the wrong direction so I shall at least keep mine intact again for a little longer (any excuse is a good one).

Good luck Geoff. Whether you deploy flaps or not, keep a cool head and don't fly too slow.

Well, it flew.......... but not for long!

After an aborted take off, when the prop came off, I tried again.

It took off OK and trim wasn't too far out. Unfortunately, on the second circuit, it tip stalled.

I almost got it back but ran out of air and it hit the deck - teach me to build too heavy.

On for goodness sake all that work what a blow i am so gutted for you Geoff

Geoff, absolutely gutted for you, it looked like a nice take off and not too much of a handful in flight.

So sorry after all that work and all the best in the future with whatever you do next.

I am gutted for you as well.

I think that many of the TN designs could be over engineered resulting in a high wing loading, especially if you make the mistake of buying a plan pack which, as in the case of my 72" Spitfire, may not exactly conform with the original material specifications.

Much as I would like to fly mine again after the re build I do not wish to be the next to stall and crash so may just leave it as a hangar queen.

Such a shame -- I know how you must feel. Like me you didn't seem to have been using flaps. Do those who have successfully flown the Mossie think that flaps would have saved us by delaying the wingtip stall?

I was toying with the idea of starting again since I've got the plans and all the equipment, but now I think I'll go for something simpler instead, with less-tapered wings. TN's Hurricane looks interesting, it uses the same motor so my equipment wouldn't be wastwed.

Hi,

I can only speak for my self, but I don't think there is something specifically wrong with the design or high wing loading. It is more fundamental than that....

1. Learnt on foam planes that have low wing loading and you can get away with "cut and glide", resulting poor technique of throttle control
2. Foam models have generally low mass and large control surfaces which helps with recovery at low air speed, results in poor apperception energy management
3. Electric is too controllable...more on that later!

Extra problems that skilled builders and experienced fliers may not fully appreciate for people like me. You guys have flown models with high wing loading and narrow flight envelopes (not a problem in its self), so you have a broad range of skills.

And here's my point

Typically the model will fly well, but it will not take prisoners if you get it too slow. high weight, high wing loading and small control throws just give too little time to save it.

I buried my BH electric mosquito (ARTF) on landing as it did not appreciate the increased drag of flaps and gear (I have to fly in with close to 50% throttle just to keep it flying). I buried my TN Ta154 last week because I slowed up to much and did not fly it to the ground.

PS

IC has and advantage, I don't like flying them with the throttle shut at low height, its subtle but I can't tell if its running of not...the result is that I am always flying at quite high throttle settings (sounds nice!). My point is that electric is very reliable, but it can get me into a poor habit...flying too slow.

PPS Flaps would have made it worse! more lift, but more drag, the issue (IMHO) was lack of airspeed (I am still learning the hard way).

Edited By Chris Walby on 26/10/2018 07:18:07

Further to the above, I also have the TN Hurri from the free plan. This uses a Tgy 50/50 Aerodrive motor the same as my Mossie but this time on 5S 5000 (1x3s and 1x2s to be able to just squeeze them in up against F1). Way over powered of course but I would have needed the nose weight anyway. It also carries a sound system and the wing loading is fine, the model being quite easy to fly.

The thing is, I also find that with the lack of motor noise it is difficult for me to get the throttle setting correct on the approach, and need to be careful with it on downwind turns. I use half then full 80 deg. of flap but if they are left in on touchdown it will invariably nose over.

From the video it appeared that the power must have been reduced (as you would normally tend to do).

I kept full power throughout the flight till just before touchdown and did not use flaps since there was a large trim change when I tried them during the flight.

Edited By Martin McIntosh on 26/10/2018 09:23:16