Smoky

David
I sort of have it in the air, It is hanging in my new shop I am building, so I havn't had a whole lot of time to work on it this year.
I have it all together I just have to do some more work on the retract doors. then final balance and fly.
cheers.
RIck.

david polley

Smoky,

Good to hear from you....I have not flown mine since last October, and I have not had the time to edit the new video I shot of the maiden flight...It does really book with the 46FX engines though. Got to get the video converteduploaded....

David

david polley

Smoky, All


Look at what my wife caught on camera last Friday..... A unexpected arrival of aMitchell B-25 coming in for a landing at our local airport... neat stuff
The link is

www.youtube.com/watch?v=P2Wee8Fz8yE

BlkHwkCE

Problem: It appears the inner construction/airframe under all the fiberglass has been assembled a little off center... Every piece of wood that is the core of the airplane appears to be shifted toward the left wing by just a few millimeters (3-5). I noticed this when cutting the wheel well covers that each gear was a little of center and after a few measurements discovered the problem was throughout the internals.
Correct me if i'm wrong here but I do not think it will make a much of a difference. I have the wings on, engines mounted and gear installed. I believe that this is just a minor flaw but the aircraft will fly just fine and if anything its purely a detail for the non-perfectionist. I do not plan on or will I take the entire center section apart to break apart the entire internal structure to move it 3-5mm to the right and then have to worry about reglassing everything. I think that would just cause more harm than good and open up the possibility to other problems resulting from the efforts to fix it. If anyone has any thought feel free to chime in

spitty

David,thanks for Your reply and the time You spent giving the Newbies all the nice tips.
Unfortunatly I can't watch the Youtube vid, because of some musirestrictions for germany..

By the way, I hate music in warbirdmovies, wanna hear the sound of the PW' s and Merlins...

Magnus, I was also one klick before ordering the Dubro Wheels, but one is 147 gramms or 5 ounces,
so that is very heavy and I think You'll get a nice trimchange..
Best regards
Andy

david polley

Spitty,

Thanks for writing.... I beleive Germany is the only place that will not play that video because of the music track.....

Here is a video my wife shot in 2008 on a test flight without the cowls on yet...You can hear the engines real nice in this video...
the link is:

www.youtube.com/watch?v=zZPewtLpsCE

David

fast_mag

Andy,

Yeah... these wheels are really heavy... I will probably use another pair. Mind you, they would give a nice soft ride . I also have the tank behind the CG, thus the two effects will work together.

One the other hand - perhaps less risk for stalling on the final .

Cheers,
/ Magnus

spitty

David,

very nice scalelike t/o and landing...( I think after searching so many hours, I know probably every ever posted Mossi-Video )

Magnus, You wrote:

The nice things with a single tank are
- The two engines will run dry at roughly the same time regardless of individual consumption
- The tank can be mounted centrally and in the Mossy below the carbs even in inverted position!!!

Lower Tank sounds good.... but ( after searching so many hours bla bla ) the Engines NEVER should go dry

I will do the carb setup so as suggested by David, with onboard glow and 2 nice Saitos ( I have some bigger Saitos in use )

they will normally and hopefully never stop !

Kind Regards

Andy

fast_mag

Andy,

"the Engines NEVER should go dry "

Yeah... I agree...

What I mean is rather that you become less sensititive to e.g forgetting to re-fuel the second tank etc... but the system becomes more complicated and in some sence more sensitive indeed even though I have had no issues with pumped engines so far. I do not say it's the right thing to do but I will try and report success or screw-up eventually. I do have room for a fairly large tank behind each engine if need be and if I get a second chance... . I understand the CMP/Jamara mossi is no longer manufactured (not in the CMP catalogue anymore)?

Cheers,
/Magnus

david polley

All,

Oh gosh, you never want these engines to quit. There is not a lot of wash out built into the wing and it lands like a brick already as it is with the engines running.
You really have to fly the model all the way to the ground and thenadding flaps and flair at the right moment fortouch down...... If one engine quits you will have to throttle back the other very quickly or it will spin right in. Bringthe modeldown very fast so you have enough airspeed to touchdown with out it dropping down hard on the runway..... all the while keeping the one engine at the idle setting...Trying to nurse it back on one engine will tend to make it snap over...... unless you add just a touch of throttle a little at a time trying to extend the glide path andkeeping the rudder engaged so it will not turn over...

Truth be told this model is a terrible glider I would suspectjust by the way it lands with bothengines running........

I have been extremely lucky in that I have always had both engines running very well together, especially in the idle state due to theway I connect the throttles to my servo guard spring assemblies...They really work well on twin engine models....so much so that I even use them on single engine models of mine, but they have to have the throttle stop screws and up until a few years ago, O.S. was the last engine maker that still had them...They since havedone away with throttle stop screws on the AX engines, hence why I rebuild older engines or modify newer ones with older carburetors. The FX series was the last run of O.S. engines to use throttle stop screw and when they brought out the 91FX it already did not have one.....

God speed and
Good luck to you all...

David

fast_mag

Hello,

Thanks David! You confirm what I foresee: It will land like a brick... I have a TF Airacobra that weigh 4.7kg for 1m60 wing span and already that comes in scaringly steep, something like 40 degrees... I never needed to land it without engine so far but indeed the engine need to quit at the right place or really high up.

I have updated the build log:
http://hansenm.web.cern.ch/hansenm/p...eDirectory.htm

I made the rudder linkage with a pull-pull and I modified the elevator linkage as seen in the pics below. Since i wanted to mount the rudder servo in the middle of the fuse it comes close to the elevator servo. No worries, there is no interference possible...

I am still waiting for the mufflers thus I cannot finally mount the engines. A trial picture is attached.
I am planning to experiment with outward thrust. The left engine will have 1 degree outward and the right engine 2 degrees. The sum will be ~1/2 degree right thrust. As I say this is an experiment inspired by Twinman and it's meant to make the control "easier" on a single engine... It means that the right engine mount is 2mm to the left and the right engine 1mm to the right of the center line in order for the spinners to line up. I will hopefully never be able to report single engine behaviour...

Cheers,
/Magnus

david polley

fast_mag

WOW, sweet build log....Very detailed and easy to comprehend....Maybe CMP should take a serious look at what you are doing here and modify their kit with your building options...
I love what you did with the rudder and especially the wheel well gear blocks... It all looks really nice..... Very nice job.....

Iam sure all ofthis will pay off when you are ready to put the model in the air. Keep up the good work and continue to let us all know your progress in this forum...

David

fast_mag

David,

Thanks for the kind words!

I glued the first wing panel yesterday and I noticed that center wing piece is not leveled when put on the table...? I had to put a 4mm balsa block under the front of the right (left looking from the front...) nacelle to make it level. Is that common?

I glued the left wing first as it had a tight fit figuring I'll be able to adjust the right panel, which has a lot of play, to make it straight. I will get something like 15mm dihedral per side (I have something like 9mm difference in height of the LE between the panel root and close to the tip). Sounds normal?

Cheers,
/Magnus

david polley

Fast-mag,

Not sure if the panel should be flat or not...When I glued my wings,I stood the wing up straightwhile the gluewas drying....

Ifirst used 45 minute epoxy....

( Imp note...!!! When you mix large amounts of epoxy (like 2 ounces at a time)the cure time is much faster that what is on the bottle.)

When I built my first wing, I used 30 minute epoxy which started to get pretty thick after about 10 minuutes...The 45 minute epoxy gives me a good 20 minutes to work with...
Anyway when I glued my wing panels, I soaked the extension tube and the flat edges with epoxy and brought them together squishing out the excess and wiping with alcohol using an old bed sheet. You will notice that if you try and use paper towels the paint they use is not realsmooth and the paper towel with come apart trying to wipe down the epoxy...so I used an oldbed sheet that I had precut several strips before I started.........
Later when I wiped down the entire model, Iused another piece of thebed sheet and sprayed the model with windex with the vinegar only,... not ammonia... and it removed the bits of raised paint and really smoothed out the models finish....

Imade a jig of sorts and stood the first wing halfwingstraight upusing bar stools and my work benchso that area where I glued the wings together was horizontal with the floor and parallel to the floor. Then Isecured the wing heavily with that blue painters masking tape. Ifound that when you use the white tape it does tend to take the finish off the model a little. The blue masking tape works much better....

Gluing on the second wing, I stayed with my bar stools and stood the wing straight up from the floor, securing the bottom with a pillow and using the bar stools to keep the wing straight and still parallel and horizontal to the floor secruing the whole thing to my model table......

So Inever glued the wing and left the wing panel on the model table...... I don't know if it should be flat or not......
Anyway, the mistake I made on my current model when gluing the wing panels was I made sure the panels were perfectly flush to each other, only later to find that not only did I not have any dihedral in the wing, it actually turned out that I have slightly negative dihedral... See the photo below looking at the model head on....

Can you believe that.......? You would think that CMP would have done that right, but no......not on my model...So...............to make sure you have the proper dihedral, you will have to have a gap in the bottom of the wing panel to insue you meet the specifications for the dihedral...Go figure, but then again I am not suprised at all about this and many other issues about all of the design flaws in the kit....

Iam sure you will see what I am talking about when you joing the wings together...

Anyway,my modellooks a little funny if you stare atit long enough, but no one hasreally noticed it was negative.....More importantly, it did not effect the way the model flew or landed, which again I feel has something to do with those new curved leading edges I installed on the wing between the nacells and the fuselage.....

Heck for all Iknow, Imay have discovered what it takes to makethis modelfly stable, which youactually have to have negative dihedral to make it flyright.... I am no engineer, but sometimesaccidentaldiscoveryisthe best way to learn something.......
One thing is for sure, if I ever have the nerve to fly this model inverted across the airfield in a weak moment of spurred on confidence, my negative dihedral will really come in handy I am sure......

David

fast_mag

Thanks David, I understand then that the dihedral may not be all that important...

I'll drop another "bomb" then... I used PU expansive glue for the dowel and epoxy on the flat surface between the wing panel and the center section.
I like the PU expansive glue because - it expands. It will creep and fill all the space between the dowel and the tube. It's really strong too. And light since it's mostly air.
Future will tell if it has any drawbacks I didn't think of. Strength should not be an issue; the main spar and even the aluminium dowel are far weaker than the joint.

I used PU glue also to line the space behind the firewall since when I cleaned out the compartment the surfaces were not completely flat. If I would have used epoxy I would have needed large amounts. With the PU glue I only needed apply a thin film that then expands and fills all cavities and it even complements where glue lacks from factory.

If you never used PU glue:
The PU glue is moist-activated. In order to "activate" the PU glue you may use a spray bottle with water as you use for flowers or when ironing. Spray a very light fog in the air and draw the part with glue through the fog. It will expand without this additional humidity but not as much.

Cheers,
/Magnus

david polley

Fast_mag...

I guess only time will tell about the glue..It sounds good being flexable and all but the vibration of those engines might make the wing panels 'oscillate" a little... You will just have to wait and see...also if the model tips over a lot with landings in the grass or attempted take offs, thatmay add some stress in those joints over time...I am just guessing but the glue could turn out to be better than using epoxy in the long run.. We will see sooner or later....

Best Wishes

David

fast_mag

All,

Quick question: will the decals in the CMP/Jarama kit deform if I cover them with an automotive poly-urethan coat? Anybody tried?

Many thanks!
/Magnus

david polley

Fast_mag...

I know that if you put masking tape across the decals they wil peel right off....you will just have to try and paint over a spot and see...
I have nottried to paint them though,however, fuel does not seem toeffectthem.They are fuel proof........

David

fast_mag

David,

Based on your information I decided to put the clear coat first and apply the decals after. We'll see afterwards in I need to paint over the decals.

The state of the construction can be seen in the pics. I mounted the engines for testing on a Hammerhead engine test stand...

Best,
/Magnus

fast_mag

Dears,

A test run of the hammerhead with straight FAI fuel over lunch confirms many things:
1) a pumped engine with dynamix carb can be a ***** to adjust
1b) two engines running at the same time does not make it easier at all
2) two two cycle engines with at full pitch with bisson pitts mufflers is LOUD.

But also:
3) two engines on one tank far away appear very feasible
4) when running dry they quit within 5 seconds from eachother
5) 20oz is plenty for two .40 size engines
6) the two engines will certainly fly the plane; I get 12500 rpm +/- 50 at full blast with APC 11x5 props. The hammerhead almost took off.
7) the two engines are very similar; with equal carb opening they deliver very close RPM.

I have to get the beast put together quickly!

Cheers,
/Magnus

spitty

Magnus,

Great build until now... Invasion Stripes, very nice retracts, first class...

I will start my PR Version next week....

Flying a twin is like flying a complex aircraft, I suggest ( I will do that for my own ) using a checklist ( my 5 cent )

Kind regards

Andy

david polley

Fast_mag

Looking great....!!!!

When I purchased my last model, they already had the decals on it when I took it out of the box. They have been applying the decals on the model for a few years now...

My first model I purchased back in 2006 had a decal sheet, but have not seen a decal sheet since....
Iwonder just how old your kit really is... or..... have they gone back to a decal sheet again? Keep up the good work....I am very interested in how your single tank and pump system will work..... Good Luck with that...

David

fast_mag

Guys,

Thanks for the positive words!

I believe this kit has been on the shelf for a while... but I don't think I can know for kow long. It did come with the decal sheet. The interior is all (bad) ply at least .

If it stops raining I'll finish adjusting the engines tonight (the pumps are really hard to get to once installed in the plane; better be correct before installation...)

Cheers,
/Magnus

fast_mag

David,

It seems like perhaps the kits in Europe are without the decals. This is the picture I find with the adverts and indeed exactly the content of my kit.

Cheers,
/Magnus

david polley

Fast_mag,

Yes, you do have an older model of the kit....If you look back at some of the first threads there were support issues and structure issues with the first generation of the model...As you have already seen, a poor structure at best. Especially for this heavy twin model...

They have done a terrific job with the covering which I beleive was solartex and then they spray painted it very well...The colors are not exact matches though. I have been through 4 models now and the green and light gray paints were always different with each model I purchased only in that after my second model of which I still have that same fuselage and have since added 2 more wings to that, the colors are noticably differentwhen I attached each newwing to the old fuselage..........

Worse even still is that when I added my fourth wing to my second fuslage the wings was slightly twisted in relation to the horizontal stab... It really looked awkward....so I had to add anextra layer of rubber to one side of the wing saddle to put the wing and the horizontal stab parallel to each other....
China Model Productsdoes not have a strictset of "standards" when it comes to the paint scheme and the moldings of the fiberglass I would suspect...I would think everything would be the same but it isn't. Each and every model has it's own personality and you have to really look overeach one to find different issues that could cause problems down the road.......
I personally feel that the way this model wasdesigned and the way the instruction book was written, it was never CMP's intention for most folks being able to keep their model for very long... Calling it an ARF is very misleading and never should fall into the hands of a new pilot or Novice builder...You really have to know what you are doing and have the knowledge of building models and understanding all about thestructural assesments that go with it...

And.....,you have to be a really experianced pilot to get this baby off of the ground......

When Ifirst saw the model, it was in an article in Model Avaition in 2006 and was sold in the U.S. under "Giant Scale Planes.com" After just 3 or 4 months they quit selling it I am sure due to all of the failed attempts by many to get the model in the air... I have seen more crashes of this model on Youtube than I have of almost any other rc modelout there...........

Which is why Iguess I have spent so much time trying to get all of the problems about the model out there in this forum...

And.....I do love a challange and have enjoyed the ride of success getting her in the air and watching her blaze the skies....When all is said and done, once you get it in the air and have that first successful flight and landing to go along with it, you too will be hooked...This modle really has "presence" in the air and it will draw a lot of attention.................
Getting it in the air is the biggest challange, but if you can do that you have succeeded.......

One final note....! If someone like "Great Planes" "Hangar 9" or "Top Flight" ever came out with it's own version of the de Havallind Mosquito in an Arf Kit with glow engines, it would sell like hot cakes because everyone in the forum would purchase it and try the modelagain just to see if they would have any better luck with it....

Hmmmmmm................! Makes you wonder why they have not done this yet.........My suspicion, they know a tail dragging twin engine, glow fuelmodel, may cause them more problems than profit......., Hense they have stayed away form the mosquito...Electric versions are out there but not glow fuel models...Only CMP has the market on that and until someone else challanges CMP's market share they are the only bank in town....... and we are at there mercy............

David