cathurga

Kahloq, I don't disbelieve your thoughts on this, I am more confused than anything else...there seems to be a VERY large discrepancy on this matter. In this thread, and on rcgroups, there are people who are flying this model as far back as 122mm, and then there are others on 100mm. The manual is most certainly wrong, and some people have found that out the hard way. But even 110mm is a long way forward of the manual spec.
This is really disturbing as I have to secure the battery tray now that I have taken the measurements and the epoxy and fittings will add some more weight up front so I think I am going to be on the nose heavy side of 110mm when I am done.
My plane is VERY heavy because of the mods I made, I cannot move anything further forward, I think I am going to have to risk the maiden as is.

kahloq

My plane weighs 16.3 pounds and flies fine. Weight is not really an issue. I rechecked what I posted back in early 2012 about where my CG is..........110mm from LE against fuse....... and NOT from outboard the nacelles. This is the part that the manual has wrong. Ive edited my previous post to correct anything I remembered incorrectly......so if you got it around 110 against the fuse you should be fine.

cathurga

Dude!!.....pheewww, you had me in a twist there for a minute[X(].

Ok, so that is good news, I reckon I will be close to the 108mm by the time I am done, and I am happy with that. I plan to open the bomb bay doors and make some other mods later if she flies well. I also want to paint her in a nicer scheme, make changes to the landing gear and it is reassuring to know that she can handle being a little 'tubby'!

Thanks for the update and clarification!

I am really excited to get this machine up in the air now. Missed out on taxi tests last weekend so will defo do some this weekend. Hopefully get some pics up too.

david polley

Spitty,

The CG should be about 110 mm from the flat spot leading edges in between the nacells and fuselage.......This is done with a CG maching like the Great Planes unit shown here....

Yes, the gear needs to be up in the wing..... You alsobalance the model right side up with this warbird.......

90% of the time you would balance most warbirds inverted, but this one does need to be right side up.....

It will be very touchy when you balance the model...You will know you are very close when it goes forward, then backwards and then forward again....There IS a sweet spot then when the model is on the 110 mm mark it will stay steady on the balance maching...Then you have it.....

I had mine at the 110 mm point when I was flying with O.S. 40 SF engines which were heavier then my O.S. 46 FX engines I have on the model now....The balance point is now exactly 111 mm from the leading edge....You would not even think 1 mm would make that much difference, but on this warbird it made a lot of difference....When I had the maiden flight with the 46 engines installed, I had to put in about 3 clicks of down trim on the elevator to balance the model in the air....I know it does not seem like much, but the fuselage is very long on the Mosquito and just a bit here and the in the nose or the tail can cause real problems if the model is not balanced....

The manual is wrong....This model will stall at the115 mm point...I know I crashed my first model whenI balanced mine at 116 mm point...It just kept climing and then it stalled and spun into the ground.....

spitty

David,Cathurga,Kahloq, many thanks for Your quick response, I also think that the Mossi will be a beast while out of MAC...
and I don't wanna learn this by the hard way....
So with the big Saitos 72 I 'm in hope,that I don't have to add to much deadweight...
Will post some Pictures of the weathering soon, it will be my prettiest Warbird I ever had...I'm sooo happy.
Guys,thanks again
Andy

spitty

David, I have the GP CG machine and I don't wanna miss it..
And I just remember my JimFox ME 163 Komet....
It's nearly impossible to get the correct CG....You really need time and patience for doing this job.
The scale of this Bird is around 1:9 , and 1-3 mm of moving the CG makes the difference between the best flying
airplane I ever had ( I have/ had around 75 ) or a desaster...
Andy

david polley

Spitty,

You are so right...A few mm is the difference between a smooth flying Mosquito and a handfull of maneuvers you will never want to experiance again in your lifetime....It is an absolute handful if it is out of balance......Get it on the mark andit is an absolute joy to fly..

David

kahloq

I have saito 91.s on mine and I still had to add bunch of weight op front. I put two 6v 2300mah nimhs in FRONT of the nose(under the clear bubble piece) and still had to add another 4-5oz of dead weight...and thats WITH using aluminum spinners.

badazzgti03

My Feedback: (4)

Finally got the order from hobbyking yesterday....too forever...got the 30mm stand offs for the motors and a set of carbon fiber spinners...was kinda doubtful on how the carbon fiber would look but it actually looks good!! Now i can get started working on this bad boy..and with a little custom work too. Does and one how a DIY on a clear nose cone delete mod? and replaced with the guns?

cathurga

Ok, so yeaterday was taxi-testing time....

I took her out on the asphalt strip, without spinners as I have counter-rotating props and the spinners are cut for normal. I left the nose cone off for the tests. I checked all the throws and dialled in expo & DR the way I like them for maidens, centered her on the runway and throttled up slowly and smoothly....she pulled down the runway and at about 1/2 throttle, the tail lifted and I had to use small amounts of rudder to keep her on the straight...throttled to full and she wanted to lift off....was reaching the limit of how much runway was left for testing, and throttle off. She slowed pretty quickly, and the props stopped as if there was a brake on them (which there is not, I made sure when setting them up). She settled nicely, no bad habits. Turned her around and headed back to to another.

I was overcome by a sense of irrational behaviour and as I throttled up for number two, I knew there was no turning back, she was going to FLY! I gave her a handful of throttle as the tail lifted and she picked up speed....no flaps, she rose gently following a slight amount of elevator, up she went!

Two clicks up elevator, two clicks right and she was straight and level. The 13x8x3 bladers have enough power but there is not enough pitch speed for my liking....she flies with authority but I would like more speed. After getting he trimmed out I took her up a little higher and tried the flaps...first level did not make too much difference in pitch, but second position caused her to ballon quite a bit. I resisted the urge to try some stall tests but rather just slowed her down to my normal landing speed, and she was fine, no untoward actions. After 5 mins I brought her in. The approach was straight and controlled, and I removed power to about 1/4 and she started sinking toward the the strip. At about 6foot up I lowered throttle some more as she was gliding more than I thought she would....still she went on, and I cut throttle completely at about 2ft, she dropped on to the tarmac quite hard, but rolled out with her tail up, and rested onto her tail slowly. I used the kit struts for the first flight, the retracts (RC Lander) handled ok, but the struts bent.
Good flight.

I now need to do some finsihing touches, and get my dual strut LG working. I was shaking like a leaf, and the large crowd at the field were a little surprised that I took her up, but all loved the flight. She does look fantastic in the air, and I thnk I am going to work on a decent paint scheme for her.

My CG is probably a hair forward of 110mm, and it certainly is a sweet spot! I also want some more pitch speed, so I am going to look into a pair of 13x10x2 if I can find them, or I will start cutting down some 16x10x3's. I will also see how many mah she takes on the recharge.

Good fun for sure, and a really nice looking plane

spitty

Cathurga,

congratiulations to Your successful maiden, it seems You feel like a boy on Christmas

And thanks for the nice flight report.

Please confirm: The CG on Your Mossi is 110 mm with Gear UP?

I wish You many wonderful flights with her.

Spitty

cathurga

Spitty, I dont know how many boys shake at Xmas time, but yeah, it was good fun for sure, and all ended well which is good.

I am going to make the changes mentioned above, and try not to upset the CG too much as it flies well like it is. Yes, I have the CG at about 110 with the wheels UP.

Hopefully I can get some footage next time I am out so I can share it on here with everyone. I didn not have enough time and nerve to do too much messing about with it, but once I have a few flights on it, I will start pushing her to do mosquito things!

david polley

Dear Cathurga,

Congratulations....Wow I know exactly how excited you must have been getting her up in the air and back down again in once piece...
Super Job.....!!!!

I know Iwas shakingso bad when Igot mine down for thefirst time, that I was gladI hit the restroom before I did the maiden flight.....

I would not know how to act if I had counter rotating props on my mosquito with my glow engines, however, Ihave really gotten use to moving the rudder full right on the begininng of the take off run...If I did not have to do that now,I might crash it on the take off run waiting for the model to pull to the left and itwould not do that.....

You are fortunate you have the electric props, but I must confess, that if you ever wanted to try it with the glow engines there is nothing like that sound....Get real comfortable with it as an electric and fly the heck out of it and learn everything you can about how to handle it under all circumstances..This way you really know what to expect...and then.....YOU just might try it again with with a set of glow engines down the road.....Of course that would mean getting another model, but you never know....You might just want to try thatsome day....

I know you have seen this but just in case, here she is with the engines purring on a test flight...

www.youtube.com/watch?v=zZPewtLpsCE

Also, Idid want to let you know about the issue of the model kind of "dropping" from about 2 feet....You will find that this is another flaw in the design.....You will needsome flap to land the model and keep it stable on the approach...It still may drop though...Ifound the porblem to be the flat spots on the leading edges of the innerwing....
One of the things I did on my model was add these leading edges (see photo)to the flat spots on the wings and I have not had any more problems with the model juststop flying and dropping hard on the runway..You will almost have to fly her in with a minium of 15 to 20 degrees of flap..(I found with the leading edges repaired, this was all I now needed) and you have to bringit in with some speedto get it to restsmoothly on the runway.....I just purchased astandard leading edge stickof balsa and made these "adapters"and glued them to the wing with epoxyto attempt to make them stilllook like radiatorintakes... Yet keep the leading edge shape to let the model fly slower and stay in the air since the air will now "cling" more to the wing at the slower approach....The is the widest part of the wing, yet in my opinionthe flat edges were taking away the largest surface area of the wing and not allowing the inner flaps to be of any use.....This $2.00 stick of balsa made all ofthe difference in the world on landing approaches, especially thecross wind type....I can not even begin to tell you what a difference this made in landing the model and looking good at it too..........( I added another photo of a landing approach)

Last, You will really pick up the speed when you place the nacells and the spinners on the model...Without the nacells there is a lot of drag on the model because of the flat surfacedfirewalls and such...when you get the nacells and the spinners on you should see a very noticable increase in the speed...So before you change anything, try it again with the same props and such with the nacells and spinners and then determine what you have to do after that....In the video I sent you, I test flew the model witout the nacells, Igained another 20 mph when I got the nacells installed..It really does make a difference....

One more thing....Is your CG 110 mm point without the nacells and spinners...? Be careful here.....When you add them to the model, the CG will change...You might want to check it again before you fly with the nacells and spinners added......

Let us know how you are doing....

David

cathurga

David,

Thanks for the kind words, it always good to get some feedback on a maiden, and potential tips for more good flights.

With regards to the counter rotating props, yes, it is very helpful to NOT have the massive P-factor when you are trying to guide a plane down a runway for the first time. I am not adverse to trying out having them swing the same way ONCE I have a decent and stable flight plan. Being able to get a pair of spinners on is reliant on me either finding an uncut spinner of the same size/shape that I have so I can cut for a reverse prop OR I have to fly on props spinning the same way (with the associated torque prob). What I am not prepared to do at the moment, is go to glow As nice as it sounds, the thought of having to tune motors to be so close, the messiness, the possibility of a motor cutting out....are all reasons that I stepped away from nitro in the first place! Not an option. What I DO want to investigate, is the possibility of a sound unit with speakers to provide some proper twin merlin noise! I am going to look at cutting the bombay open, and installing the sound unit in there....there is sufficient room for it, and it will also allow me to neaten up all the wiring and what not. I need to do some calculation on the weight penalties, but I have some options for lightening things up elsewhere.....just no glow for me mate.

I aksed the question about the leading edges to our local expert (well qualified with 25 years in jets and a regular at world events and a few titles under his belt) and he said that as they are directly in the propwash, it doesnt make that much difference. As much as I trust his judgement, I also agree with you that this flat front cannot be doing any favours to the aerofoil design and efficiency, so I will be making a leading edge slat as you have done.....it flies without it, but I doubt it will make things worse.

The COG will change when I put all the bits and pieces on it, and of course I will make sure it does not move at all! It will stay exactly where it is in its all-up config!

Regards

badazzgti03

My Feedback: (4)

Congrats on the maiden man!!!! i know those first can be a little nerve racking. I'm starting to get nervous thinking about mine....I actually started to work on mine this past weekend. Got the motors kinda mounted need longer screws for some reason the 30mm stand offs are a **** hair short. the spinner back plates are hitting the cowl, so i can throw some washers on. I have 1 1/2" screws on now need at least 1 3/4" to 2" But the carbon fiber spinners actually look pretty sweet on the mossy.

david polley

Dear Cathurga,

Yes I can understand about the glow engines and such......I totally forgot about the reverse pitch on the one prop...Yes getting a spinner for that could be difficult..........
As far as the propwash on the leading edges....Yes I agree with your friend that there is not going to be much difference with the propwash over the flat spotsat normal flying speeds.......I have flown 4 differet modelsnow and they ALL flew just great going 90 mph.....At those speeds the air is very tight over the wing.......

But my friend, since I have had 4 of these models now, Ican tell you that every one of them had the same problem dropping to the ground anywhere from 2 to 5 feet above the runway,....especially on very calm days or evenings...
With no headwind it was always much worse.......When you look at this video of my third model ( still no leading edges) www.youtube.com/watch?v=7j-pCLKLqAcwatch the landing approach at the end and you will see that even with a 20 mph head wind right down the runway, the model still droppedat the very endeven with the speed up, flaps enguaged, and full up elevator....

It just stopped flying.....Just watch and see what I am talking about.....I say this model alsohas a "ground effect:" issue too.., making things even worse....Again, another design flaw for this model, but even the real mosquitos had difficulties landing too....

I recorded this flight in slow motion and you can see where I had the flaps set and such.... (this is the same flap setting I use now and it is perfect with the new leading edges......,and when you slow the model down now for a landing approach, then enter in the flaps, the model will not rise very much at all and you can maintain the flight path without resetting the elevator trim.....That was always another problem for me since I could not reprogram the elevator setting to offset a much larger flap setting I tried to use to stabilize the model to land with....I know several folks in this forum were able to program a new preset elevator setting when their flaps were engaged.....When they hit the flap switch, the elevator automatically went into a new setting.....)

I have been flying models for 35 years now andI have never won anything at any type of flying event..., scale or otherwise.....But, what I can tell you is that from trial and error and 3 crashed models later, the glued on leading edgesreally do make a difference....

Think about it...The prop wash is negated and has verylittle effect on keeping airflow tight to the wing because the props are simply not turning very much as you are landing the model...They essentially are turning so slow on the approach, all you have left is airhitting theairfoil of the leading edge and the large flap area to keep the model flying longenough to settle her down for a much smoother landing.....There is no usablepropwash on landing approaches.....

I do have video of my maiden flight of the 4th model that I had the leading edges attached, ( I do have to get this videoon here...), and it landed just fine in the grass off of the runway with a 15 to 20 mph crosswind......I never landed this model ever this good in a crosswind like this.....I say the that this was the best $2.00 I ever spent on a model airplane, scale or sport......
Yes, Iagree with you that it just will not hurt anything putting them on there.....I say you will see a difference on you landing approaches......Please let me know what happens when you add them to your model....

David

Dangaras

Ok, this falling out of the sky thing is annoying to say the least! However, it is what happens when you dont fly your mozzie right down to the ground...

My BH mozzie is 66" WS and weighs 7 lbs approx. Now I used to have those landings when I first started flying her, come in lined up and 3 or 4 feet off the ground I would pull the throttle back to 25% or less and try to glide her in resulting in the inevitable "fl0p"..  Repeatable every time.

Then I tried flying her to the ground under power once and the landings were beautiful after I mastered that technique. Mozzies dont glide well, fly them to the ground and dont cut the throttle until she is down and rolling... Never had an issue since.

my 2 cents..

david polley

Dear Dangaras,

Yes you will not experiance this problem I would imangine because you BH electric mosquito does not have these "flat spots" we are talking about here with the CMP mosquito.... (photo with the original decal on the flat spot shown)

Also, toget the correct CG ofthe model at the 110 mm point, most of us have had to add an additional12 to 16 ounces of weight in the nose to get the model to balance at that point...A 12 pound model is the norm with glow engines on the CMP version of the mosquito.....My Mosquito is almost 13 pounds....which does not help at all with the landing approaches...We need all we can get, hence the added leading edge on the model.... with flaps engaged, and a fair amount of speed gets her down successfully I believe....

This is what we are talking about...adding the fact that yes the mosquito does not glide very well, and yes I agree with you that you have to fly the model right down to the runway....all issues you have to do when the model is right to begin with.....

David

Dangaras

David,

the BH mozzie radiators are very large and present, so flat spots are also a part of my kit.

I had to add weight in the nose & put the 4 cell, 4000 pack right up front to get her to just balance.

The one thing I forgot to mention was finding that perfect looooong, shallow approach that setup the perfect landing. I have flown at fields that required steep approaches but was able to create the shallow glide after such a short final... That's with full flaps (both are present inner & outer)..

One of the biggest mistakes made with flaps is NOT realizing that flaps require MORE power to keep flying, less requires in stalls & flops...

Practice and repairs leads to less practice & repairs....

cathurga

David, even before your convincing argument on the leading edges, I was sold on the idea of putting something there to even out the airflow, but I still appreciate the points you make. They will at some point go on :-)

Dangaras, I hear you, and I can tell you that I am a person that brings my plane in hot ALL the time.....regardless of wing loading, weight or otherwise...I do it because I like to fly them in, I also like a scale(ish) roll out if I can get one. Adding to that, if something is going awry on the approach, I have a better chance of going around if it is 'moving' than a plane that is porpoising in at just on stall speed. With this plane, I followed the same tactic I always do....as I cross the 'piano keys' or the 'numbers' as they call it, I tend to close down the throttle to almost a stop, and glide in, but this thing lost height VERY quickly, the props stopped instantly! I dunno if them stopping immediately had anything to do with it since a windmilling prop presents more of a surface 'disc' than a stopped prop...anyway, she touched down on mains, and still rolled out quite a way with her tail in the air, and then settled onto her tailwheel, so she had forward speed for sure. I will just be more wary of it next time, and wind the throttles back a little slower.
Remember too, that mine weighs in at a hefty 7.1 kg's which is on 15lbs, so she is tubby. My landing was flap-less and in hindsight I should have had just the first level of flap, as it did not affect flight characteristics the way full flap did, and I think that little extra lift would have minimised the abrupt altitude loss....I am glad I did not do a stall test, even with enough altitude, with that sort of result on landing, I fear that she might have gone into a spin, and not recovered! Not nterested in that problem.....I will keep her flying at all times.

David, with regards to the mixing of elevator into the flap settings, my Spektrum DX18 is more than capable of doing it, I just need to work out whether I want to do it as a part of the flight modes, or if I want to do it as a mix with flaps. Some people like flight modes to manage all settings because the trim settings change with the flight mode as well, so once it is set, all the trims act with it and there is no drama. But in this case, I am thinking with two stage flaps, I might increase the first flap mode a little, and see how she fares, if it is managable, then I might ignore the second stage altogether. None of the models I have ever flown have had (or needed in my opinion) flaps. But this one might need a tad.

I will get her set up how I want her, and then I am going to just enjoy flying her.

Thanks for all the tips and suggestions guys, alll appreciated and taken in the spirit with which they were intended.

P.S....Badazz.....good luck on the prep, hope to hear a successful maiden for you too, and that real soon!

cathurga

Dave, forgot to say....Great video, especially the slow motion and accompaniment :-) Good landing too.

I will admit that the strip where I am is about three times longer than yours, and at least 5 times wider, so I have NO excuses for not hitting the right place, and for keeping speed up.

Dangaras

It really comes down to practice. The more you practice the more you learn the characteristics of the model.

Good luck and happy flying..

david polley

Good points by all.....That is why I like the forum so very much.. Just a wealth of knowledge by everyone...

Happy flying...

David

badazzgti03

My Feedback: (4)

thanks Cathurga!!
Ill be doing away with those flat spots on the leading edges. The previous owner of the wing made small vents in the leading edge. Ill be making them bigger and more scale like and a nice spot of the ESC. Have a enter and exit for airflow. Gotta fine some pics of the real vents

Dangaras

Here is a picture of a BT mozzie at 89ish inch WS should help you with the air inlets..