Tony Major DH Mosquito

[A.A. Barry]

Craig somehow i got the thought that you where using OS 52's any way there just a copy of the os some tuning should be the same proceedure, I have checked out your header, it looks Ok what size is the hole through the middle of the preasure take off adaptor, did you run this to check out the unit???first .

If none of above fix the problem, you will just have to remove the motors , set them up so all is good and then stick'm back in.... a pain but hat else can one do

Barry

[Craig Spence]

Hi Barry,
Thanks for the compliment on the exhausts, they were a pig to fit in.
I'm not sure what the "pressure take off adaptor" is. Is that correct term for the back pressure nipple.
If it is, it's the same nipple which came with the engines supplied exhaust.
M3 tap, so I'm guessing the hole would be 1.5mm to 2mm, I'd measure but my wife has lost the tape measure and my ruler is in 16ths and 10ths lol.

I think the back pressure to the tanks will be fine due to the positioning of the nipples.

I spoke to my old instructor about the engine. I remembered that he richened up the lower end for running in, this would explain why it's so rich.
It also perhaps explains the cut outs on idle, too much fuel coming in on lower revs choking out the glow plug.
It would also explain starting issues, higher torque on starting, runing backwards, plus what was said above.

What do you think Barry!.

Cheers,
Craig.

[A.A. Barry]

Craig, whaty I meant by the pressure nipple adaptor was what size hole for the exhaust gas goes through the unit

seem s like your instructor maybe correct

keep me informed

Cheers

Barry

[Craig Spence]

I'll keep you posted Barry, thanks again for your help.

Craig.

[Craig Spence]

Well doesn't seem like I've got far this trip off.
The engines are continuing to baffle me as well, I returned them to factory settings at the field and they were purring like tigers.
Both almost bang in the RPM range, however the left engine does not like idle and cuts, it is also still running quite rich.

When it comes to the maiden I have my old instructor and a couple of four stroke engine gurus to get them bang on.

Heres the big problem though, the weight.
Whilst trying to get the CofG sorted I realised how heavy the plane is going to be.

All in all, I have to put 1 1/2lb of lead in the nose along with two batteries.
I was expecting quite a bit of weight in the nose but not that much.
Brian Taylor had 1lb approx in the nose.

My old instructor thinks it's quite heavy.

I'm unsure of what to do really.

Here's BT figures off of the plan.
11lbs 10oz for the plane less fuel and bombs.
12oz ballast in the nose.

The engines used were OS25FSR and props 10x6 turning 10000 RPM.

My set up.
Plane, 9 1/2 lbs. Although I consider this may be wrong due to the scales, I'd add about 3lbs.
1 1/2lb ballast plus batteries.
AUW minus fuel 14lbs including the added 3lb because of luggage scales.

Engines are SC52FS turning 12x6 at 9200.

My concern is not that it won't take off, it's how long will it take to get airborne and how much of a run will I need for landing.
Our patch isn't the longest.

Barry, if your there, does this sound too heavy?.

I have a few ideas to reduce the tail weight.
1; remove the rubber and alloy hubed tail wheel and replace with a foam wheel.
2; remove rubber and alloy hubed main wheels and replace with foam ones. These weigh quite a bit and sit behind the CofG.

That's as far as I would go really.

The other options are, which I wouldn't like to do are this.

Remove tail cone and make a moulded which will be a little lighter, but not much.

Take out the elevator and rudder servos from the fuz and fix them to the wing.

And very last resort, removing the elevator and making a hollow one.

Any help or advice appreciated.

Thanks in advance, Craig.

[A.A. Barry]

Craig yes it is heavy, how do you build??? on the heavy side pos like me, B.T would have selected all is wood weights and only used enough glue to do the job, mine is also heavy, but I put this down to all of the above and useing RCV58 CD's + F/Glass fus.,

your homemade exhaust could also be adding more weight, the Sc 52"s are a copy of OS, and I guess a few grams heavier, the OS 56FS which is an upgrade of the 52's, and that weighs in at 419gms, so B.T. used OS 25FSR... why????.... lighter and as much power, they come in at around 357gms, so you have already loaded up the model by 114gms before you start, add all these little things up and you have done it, as I have too..Your paint and filler may also have added more weight than B.T's

shift your servos forward, and use foam wheels, move everything forward of the CG, use lighter servo's

Back to ya motor , I'll say it again.................get the little spinny round things OUT, and bench run em, there is not a lot more I can suggest, except don't fly with that dicky motor... the end result will be a full rubbish bin, once you fix that problem it may well be a sucess, remember there is a lot of flaps to land quite safely

Chers

Barry

p.s Take them motors OUT

[Craig Spence]

"Craig yes it is heavy, how do you build??? on the heavy side pos like me," lol, yes sometimes I knowingly build heavy, thinking it may save time with some fidly bits, but in the long run it just creates more time.

But generally I tried my best, getting the lightest wood from the shop etc...

"your homemade exhaust could also be adding more weight" unfortunately these have to stay.

Your right though, I should have expected alot more weight with the bigger engines, glass cloth, filler etc.. Lesson learned for future projects though.

I'll have to see what I can do with the servos, the trouble is I'd have to make up an extra connection for them, the rods that is as the wing comes away. Another weak point which I wish to avoid.

As youv said about the engines, your right I'll get on it when I get back.

I suppose with all the added extras like you said there's gonna be a gain. However even BT's prototype was a heavy beauty, I can only hope mine flys as well as his.

Only time will tell.

Three weeks time the maiden will defiantly be going ahead. On a Saturday, the cowls just need finishing and spraying along with the doors.

Just glueing lead in place, pulling through another wire for the extra battery up front and making battery holders is all that's needed for the first flight.

Hope it works out, ill let you know.

I will take the engine out as well, cheers.

Craig.

[Craig Spence]

Well it's been a while now and I haven't touched the mossie.
Haven't had the heart really lol.

I devised a plan but was hoping someone could advise.
I have decided to cut the tail cone off, I will make a mould of it to make a plug and then vac form a cone.

Can anyone advise on materials and methods for this?, it would be greatly appreciated.

Also while the cone is off I will be looking at changing a few small things. Trimming off bits of wood where I can without compromising the safety of the plane.
A foam wheel as well with no collets.

After that has been done I will see if it's feasible to move the rudder and elevator servos onto the wing. This I can't see happening but will take a chance with it.
Anyone know of a good way to connect and disconnect two pushrods?, this is what I will have to do, any gadgets out there?, or will it have to be bell cranks?, which will again add more weight.

Foam main wheels and I am now also considering engine changes. Thinking two 46 two strokes, same power but lighter, hopefully, it still wouldn't help the CofG though.

I know a rebuild lol!.

Any help would be greatly appreciated, cheers all.

[Danny Fenton]

Hi Craig, I am going to suggest blue foam. I have used the stuff on my Hurricane radiator "Boat" I have managed to make mine half the weight of a frineds balsa equivalent, and he does not build heavy believe me.

Here is the carb intake for my Hurricane

The stuff sands and shapes superbly. One coat of 25gsm cloth with EPOXY resin conforms to the shapes really well. The carb intake above was amazingly covered in one piece of "quality" FighterAces cloth

If you want it really light you can dissolve the foam away with celly thinners, but it really doesn't need it.

I would get all those servos forwards, as far as you can. If its heavy then its heavy, just don't slow it up

Cheers

Danny

[A.A. Barry]

Craig this is very dramatic....""""I devised a plan but was hoping someone could advise.
I have decided to cut the tail cone off, I will make a mould of it to make a plug and then ......""ïf you feel you must then all the best

Barry

.

[Craig Spence]

Hi Danny, thanks for the info there, much appreciated.
I did originally use blue foam for the cone, but I used it as a plug then glassed over it.
The problem was that when doing the fairings I used blue foam and P38 which was stupid as I now know.

I think I'll do as you say Danny and build up the tail cone "again", with blue foam, then remove, glass and hollow out.

I have thought of a few other options as well.

1; remove the rudder, use 16th ply centre plate, 16th balsa ribs and use blue foam for the leading edge and top. Then cover.
2; remove the elevator which is solid balsa, do the same as above but glass.

This should remove quite a bit of weight, but well see.

Thanks Danny, always appreciate the help.
Looking forward to seeing your hurricane come on.

[Craig Spence]

Hi Barry,
I don't mean to make it sound dramatic, but to me it is.
I've invested alot of time and blood into this model and I'm very worried it won't make a flight.

Now I'm just thinking of all the things I can do to lighten the load.

Cheers, Craig.

[Danny Fenton]

Sounds like a plan Craig

On the Hurricane front, I am looking forward to seeing it come on too

Keep at it you will get there

Cheers

Danny

[A.A. Barry]

Craig

It will be interesting to see how much weight that you will save

Barry

[Craig Spence]

Cheers Danny,
I think it's gonna be a while realistically before it's ready but I suppose that's how it works.

Hi Barry, yep, I don't think it will save a great deal but as you know the fuselage is very long so even a little bit of weight off the tail could add up to alot less weight in the nose.

I'm pulling at straws really and it's frustrating.

Cheers, Craig.

[Martin Harris - Moderator]

Posted by Danny Fenton on 06/05/2012 17:05:32:

Here is the carb intake for my Hurricane

I like it Danny, but is this really part of a model aeroplane???

[A.A. Barry]

Craig, here is an intersting point, the US guys build models that are 80" and above and most of them weigh in at 18 lb and above, powered by bigger engines that we use, Zenoh 62 and such, yet they have no problems flying them.... just a thought

Barry

[Craig Spence]

Hi Barry,
It is an interesting point.
I have no doubt it will fly, my main worries are landing lol.

Our patch is quite short, so take off needs to be before I hit the end of the patch (long grass) or the trees.
Landing needs to be kept within the boundary as well or it will hit a fence.

Maybe I should roll out a groundsheet at the end of the runway and cover it with slush, as this would slow it down dramatically lol (air crash investigation, discovery).

It's just gonna take time I think. Have you flown yours yet Barry?.

[A.A. Barry]

No not yet, I have busy with other projects, but that one is next on the list, built a couple of easy sport models out of RCME free plans, Harmony and a Jitter bug. , I must get back to it

Barry

[Francis Routley]

Hi, can you help?

Can you tell me which copy of the rcme this Mosquito plan was in.

I am going to buil the plane my self as my first scale plane.

Your build blog will be of great help to me.

Regards Francis

[A.A. Barry]

Craig, here's a couple of pics of the finished mossie internal nacelle

[A.A. Barry]

you can see the door and U/C sequncer at the back

[A.A. Barry]

and a pic of my Do215 that I have just finished as well, this one has no retracts or flaps and is E/P powered, battery is in that huge cockpit 5s x 5000, it is 65"and wieghts in at 4.5 kg 

Edited By A.A. Barry on 01/07/2012 01:55:26

Edited By A.A. Barry on 01/07/2012 01:56:50

[Craig Spence]

Hi all,

Well after a very long break I have came back to the mosquito.

I removed the solid elevator & made a built up one, tail cone remade as a two part cone to allow access to elevator & rudder linkages.

Rudder, elevator servos moved forward & tail wheel changed to small foam one to help with CofG.

Made a dual battery holder in the nose along with pouring nearly a pound & a half of lead in the nose. CofG just about bang on now.

I found the issue with the engine that kept cutting out, I had a servo which was moving erratically by itself, this has been changed out now & both engines are achieving about 13min plus before one cuts out.

On the low end the engines are out by 10rpm, this will be easily sorted by leaning the rich one.

So there are only a few small issues now -

1: I had to change the tail wheel to a castoring tail wheel - big mistake!. The plane literally just goes round in a circle when taxiing, torque & thrust?. So plan is to add a mini servo & a snake back to the tail wheel.

2: Cowl adjustment - add extra fitting points (not happy about this!, something not scale ruining the look).

3: Undercarriage doors on STB nacelle - one door is warped!, a little bit of patient bending, taping & leaving overnight I think.

That's it!, I'm awaiting a pilot to maiden it for me.

I shall take some photos of mods & vid maiden. After successful maiden (hopefully!!!), I will be doing more weathering, panel lines, wing tip lights, antenna etc, etc... It continues to go on & on lol.

Cheers,

Craig.