Smoky

Ouch.
sorry for your loss.
where did you balance it?

In my humble opinion, and assuming it was balanced, you needed more speed, and a shallower climb out. I tried to listen for the engines, to see if one quit, but the music was too loud.

On my take-offs I learned to hold the nose down until she had lots of speed, and then just relax on the stick and let it rise slowly and gently.
I've had mine do a hard snap at high speeds, just by being too agressive with the sticks.

again this is just my humble opinion.

david polley

Dear Aitzolius,

Brother I am so sorry about your Mossi going in like that. [&o]

I could not hear anything on the video. Did one of the engines quit on take off...? Did you meassure the CG carefully. It should have been about 110 mm from the leading edge between the nacells and the fuselage. If you had retracts, they would have been up when you balanced the model for the correct CG.

If the engines or radio did not fail, and the control surfaces were ok, and the CG was correct, then you may have pulled up to quickly and did not have enough airspeed and the model snapped over because of the engine tork.

It did look as though you ran out of runway and tried to pull up too soon to avoid going in the brush.

Warbirds can snap over very easily even if they just have one engine like a P-40 Warhawk or a P-51 Mustang.

With my Mossi coming in at a hefty 13 pounds I have to use more than 3/4 of our 400 foot runway for the Mossi to get the airspeed I need to get her off the ground. I could not tell a whole lot but your model does look repairable. Can you repair the model and give it another try? Just asking... I hope you can fix her up.

Take Care

David

Aitzolius

Hi, David and Smoky, thank you very much for your time!

I just see that the Cg had about 120mm, between fuselage and nacells, because I read this point in somewhere. I started running progressly with half flaps and maybe was a short take off. The engines goes identically because we were some time adjusting the speed of each engines. At low and high speed goes very very similar, with very few difference, and at half throtle, had more diference, about 200rpm.

But you are right, I was very nervous and when see in the air, I climb it very quickly []

It is my first twin, and I was flying some Stangs and spits.

It is very repairable, my friend tell me that he help me with the repair to put at the field as quick as possible.

In the minetime, I just waiting for the Hangar 9 B-25 for this saitos 62.

For the second try, I will put the CG at 110mm.

Will inform you about all the progress.

Best regards,

Aitzol.

david polley

Dear Aitzolius,

Yes the CG at 120mm will make the model too tail heavy. I lost my first model because it was too tail heavy. I later found that the 110 mm point does make it a bit nose heavy, but man o man she flies really well with the CG there.

I understand you wanting to try and take off the model with flaps, but you do not have counter rotating propellers. The tork of the 2 props gong in the same direction will roll the model over because the flaps will cause the model to get into the air too quickly.

You really need to take off the model without flaps becuase you need a lot of airspeed to overcome the prop tork and the fact that there is no prop wash from the engines that really effect the rudder either. You almost have to take the model off with the engines running very closely together until you get enough speed for the rudder to actually make a difference on the take off run.

I hope you get her back together real soon. Use every bit of you runway that you have, make sure the CG is 110mm and do not use flaps on the take off run. Work with the adjustments of you throttles to get the engines together as closely as possible. If they are not together, taking off the model becomes very difficult, especially on pavement...

David

Brad330l

My Feedback: (1)

Were those ailerons reversed maybe? It really rolled very fast.
Sorry to see it.

Brad

david polley

Smokey, All......

Great success last week in getting my rebuilt CMP mosquito in the air after 14 months. I was able to keep the fuselage and built a new wing from my 4th kit. So, I have my second fuselage connected to my 4th wing. I did get video of the maiden flight but still in the stages of transfering it to something I can load on youtube...In the meantime I will add photos of changes I have made in this forum. These are the changes I have made to the kit since I started building it in 2006...

First, I moved the CG from 117mm with my first model that I crashed, to the 110 mm point, measured on a Great Planes CG machine with the model upright. For you folks that have retracts, make sure the retracts are up in the wing before you balance. My new 4th model now has the CG at 111 mm, again all measured between the nacells and the fuselage on the balance machine. I custom built the pushrods with 1/4 in spruce sticks, heavy duty Great Planes push rods and clevisis, and Sullivan Heavy Duty control Horns . In the first fuselage I was using standard servos in the rudder and elevator. They just were not strong enough to control the model, especially in the rudder area. I placed Hitec HS-965MG digital servos in their place (see photos)

david polley

I gave up trying to work with the internal set screw and collar system they designed for the rudder and tail wheel. Even with the 4 screws tight and secured with loctite they alway stripped and the rudder and tail wheel would start to slip when moving the rudder servo after each take off. (see photo)

I got real tired of that so I went external and connected a custom made push rod directly to the rudder for better control. I know it took away from the scale apperance and all, but what difference did it make if I couldn't get the model off of the ground. I took 2 of the Great Planes rods and soldered them together and made a Z bend and exited it out of the fuselage. (See Photo)

That worked real well with the high tork digital servos. I just soldered a tail wheel to a wheel collar and then soldered that to the stem exiting through the brass tube and wood brace in the tail section. Once I had the clevises center as you can see, I soldered them to the threads to take out any extra play in the control surfaces. That also helped with control of the model on take off. I had to put a small wood brace back there to support the exiting rod. The screws don't make it pretty, but they keep the brace in place firmly which takes out any slop in the rudder on the ground.

Another problem I had with the first model was how flimsly the tail section is built up. In the early attempts at trying to take the model off of the ground with the poorly built under carriage, I ended going off the paved runway a lot. That in turn always had my model up-ending in the grass and it would flip over breaking props, and worse break off the top of the rudder.

One time It flipped over and the rudder crushed itself. Since there was no support there it also ended up breaking the canopy. I was not a happy camper after that. I was so frustrated at the rudder breaking I ended up flying it one evening with the top broken off.

When I built the second fuselage, I peeled back the covering and exposed the very weak built up framework of the rudder section and epoxied very thin 1/64 inch plywood sheeting to the framework and then coverd the area with some very old red "Valkote" I have had since 1984 in my collection of iron on films. It is low heat and goes around surfaces very well, so that is how the red tail came into play. Another trial and error fix I guess. I have had several nice comments about the red tail. It goes real well with the paint scheme, so I added some more of it later on on the 4th wing I just built.

Since I beefed up the rudder, I have flipped it over several times since and it has not broken yet. I would warn anyone that wants to do this, that when you are finished, you will have to readjust the CG again on the model. Just this little bit of extra weight in the tail caused the CG to move on me from 110 mm to 114 mm. The fuselage on this model is very long, so just even a little weight in the very back of the fuselage will need to be addressed unless you do all of this first before setting the CG.

You WILL have to add as much as 16 ounces of weight in the nose, give or take, depending on the engines you use. Again if the CG is not set correctly on this model, it will stall, snap over, and spin into the ground.

david polley

Another modification to the fuselage was to cut away a large access hole for me to get my hand inside with the canopy. Since the canopy was glued into place I didn't have a way to access the pilots if I needed to later on.

I had an incident with my first fuselage that came about the second or third time I started the engines. Both of my pilots came unglued inside the canopy. I glued them in place with a spot of epoxy, but they broke away, because I glued them to the paint and not the fiberglass. They both popped off and were rolling around inside of the canopy when I had taxied back to the pit area. I had to cut the hole so I could get my hands up in there and resecure the pilots. This time I used RC 56 to glue the pilots in place, then I ran a self tapping screw in the bottom of each pilot bust to keep it secure until the glue set. I just decided to leave the screws in there.

So how do I cover this hole and still make it look nice? I work on all kinds of test equipment and the instruments I work with usually have cooling fans in them to keep the power supplies from overheating. To keep the dirt and dust out of the equipment, there is a filter inserted in front of the fan to keep it clean on the inside. I used a fan filter to cover the hole and I thought it took care of the problem nicely... I have to give credit to my sister who painted the Willimas Brothers 1/6 scale pilot busts. She does a nice job. If you zoom in you can see the detail on the eyes. She did that with a toothpick. I will add more over the weekend.

David

(See photos...)

david polley

Smoky and all....

The wing has certainly been a challange. You do not want to glue the wing panels on and then try and mount the engines and the gear. It is a lot easier getting the engines mounted, gear installed, tanks installed, and servos installed and tested with the center section of the wing then trying to modify everything with the wings fully completed.

The first thing I did with the model including the fuselage was toss out most of their hardware. The metric hardward is hard to thread and it strips out, especially when trying to mount the engines. I went to Ace Hardware and purchased all US threaded bolts, blind nuts, washers, lock nuts, and screws. It was just easier that way for me.

Before I started on anything, I mounted the wing in the saddle of the fuselage and used Dubro Brass Threaded inserts and standard 2 1/2 inch 10-32 screws to bolt the wing to the fuselage. I also use nylon washers with the screws to keep tension on the screws so they do not start to come out. I suppose I could have used nylon bolts, but I just felt better about steel screws.

Check the angle carefully so you drill into the mounts. I found the brass inserts were so much easier to work with than using their blind nuts in the kit. I also added the same 1/64 inch thin plywood with epoxy in the saddle areas for support and to keep the fiberglass holes from splitting. (see photos)

The tanks that come with the kit are not even 8 ounces. The 7 ounce tanks will give you about 5 minutes of flying time, if that, depending on the engine. Also the rubber gaskets that come with those tanks will get hard and leak air just after 1 flying season. I think anyone that is serious about this model and using 2 stroke engines will have to go with 40 sized engines and 10 ounce tanks.

I have a very hard time thinking this model could get in the air using 25 sized engines. I know the reviewer in AMA magazine in 2006 used O.S. 32SX engines to fly his model and 10 x 4 inch props. In my world, that would be the smallest engine you can get away with to get this bird in the air. Anyway...

I cut away all of the wood surrounding the tank installiation and went with Sullivan 10 oz round tanks with Dubro's new black rubber stoppers that are availble from Tower hobbies. Those stoppers did not leak and they kept their elasticity much longer.

My first model used the older O.S. 45FSR ABC engines and it was under powered. I struggled to get it off the ground and keeping it in the air. I have 2 small video clips using the 45's here. The first video is of my first model before it crashed from being to tail heavy. it was shot with a camera phone and all he got was the take off. It stalled and crashed right after the take off run. This video was taken in July of 2007. It just kept climbing and I could not get it leveled out in time.

http://www.rcuvideos.com/item/64Y4JQJXN1408L8B

The next video was of the second model I built. I had more weight in the nose this time and had the CG at the 115 mm point. I still had faith that the 45's would be enough power, but it was still sluggish getting it off the ground and still too tail heavy. You can tell by the way it bounces it was still too tail heavy... That link was shot in the Spring of 2008.

www.youtube.com/watch?v=ICW_PBKAsOo

I decided to take out the 45's because of the smaller carbs and I went with the O.S. 40SF engines after getting them from eBay and rebuilding them. These engines used the "4D" carburetor which had a larger opening and the engine head on the 40 was thicker than on the 45 allowing cooler running and more power. They would also mount in the same holes as the 45's so installing them was very easy.

(I like rebuilding 2 stroke O.S. engines. It's part of the fun in the hobby for me...)

I have a photo of those engines mounted. These are O.S. 40SF engines and the older O.S. 45FSR mufflers with double muffler extensions to clear the cowls. I didn't want to cut out the cowling to install the muffler inserts as they had them in the manual. I think over time I saw a problem with fuel draw, in part I beleive, because there was too much fuel line between the muffler extensions and the fuel line going back into the gas tank. I also suspected I lost out on some muffler pressure as well becasue of the distance of the extensions used. The engines always eventually ran well, but I had to wait until they came up to speed and the engine settings were very touchy starting with a full tank of gas. For most flights, I ended up only putting in about 8 and 1/2 ounces of gas in each tank so the engines would not lean out too much with the 10 ounce tanks installed. I was also limited to 10 inch props since 11 inch props loaded the old 40's down too much. I have a video with the 40's mounted on the model. Better performance and the CG on this model is 110 mm. That link has become pretty popular and was shot in July of 2008 by my wife..

www.youtube.com/watch?v=zZPewtLpsCE

I finally went with the O.S. 46 FX engines and 11 inch props. I spent the extra time cutting out and installing the muffler inserts. I then only needed 1 muffler extension instead of two. I can also get both engines running with full tanks of gas and they stay consistant during the entire flight. I noticed that right away with the 46's. Smooth engines....

Because of space limitations between the firewall and the engine, I removed the needle valve backplates from the 46FX engines and the carburetors and placed the older O.S. 40 SF backplates and "4D" carburettors in their place. (photo of the 4D carb below). These are great carbs and with the adjustments up front, are easier to work with on this model... (see photos)

I have more coming in the next few days

David

Smoky

Nice
mine is ready to run,, just have to find the time.. but busy building a shop/hangar for my 6 models. The wife say's the take up too much room in the house. gotta love her

david polley

Thanks Smoky

I know all too well about time.... 14 months to purchase another model and build a wing just to get her flying again.......

However.........

It was all worth the trouble once I got her in the air...... This one flies real nice too...

David

kahloq

Think I might get one. I have some saito 91's lying around that I dont see ever being used, so this would be a good candidate. Yeah I know they are a bit long, but I can make that work.
I have a saito 52, but not a matching engine. Not going to buy another just to fit this since I have 3 saito 91s around doing nothing.

david polley

Dear Kahlog,

Thanks for writing. I believe your Saito 91's could be a bit too much power for this model. The original plans called out for .25 to .32 sized 2 stroke engines, and you will find in this forum that this model would struggle with 32's because of the weight that has to go in the nose to balance out this model. Up to and over 1 pound of nose weight depending on your options with engines and if you will be using retracts.
I started out with a pair of rebuilt O.S. 45FSR engines and it struggled to get in the air. I then went with rebuilt O.S. 40SF engines which had bigger carburetors and more power. It flew prettey well once I got it in the air, but still struggled with it on the ground. When I finally went with the 46FX engines, I got the power I needed to get it off the ground quickly and can throttle back once I get it in the air. With the 46's it will cruise over 100 mph or about 3/4 throttle.
You will have to excuse my ignorance about 4 stroke engines but I believe a .91 four stroke is about a .75 2 stroke or close to it. If that is the case, I think it would be too much stress on the wing and it would be way over powered. Just my opnion...
If you go through the forum, you will see what others have done and why.

Good stuff here...

Good Luck

David

kahloq

Thanks for taking the time to reply. Ive read this thread since the start. Yea I know the 91's are bigger then necessary. Im npt using them for speed, Im using them cuz thats what I have and Im not going to buy a new set of motors.

I bought the Mossie for the simple reason to use up motors just lying around. More then likely I will simply use 12x6 or 12x8 3 blade props and manage speed using the throttle.

david polley

Kahlog

Sounds great...

Yes the 3 bladed props will pull down the engines and that may very well work....
I would avoid snap rolls Ha Ha

Good Luck

Keep us all up to date on your progress through this forum...

David

kahloq

One thing Im thinking of doing is programming differential throttle in conjuction with rudder for takeoffs. Ive done this on a couple other twins I have and it really helps keep a plane straight on take off ince you gert the right percentage dialed in.

Smoky

Kahlog:
The .91 4 stroke is about the same as a .61 2 stroke. a little more torque and a little less RPM.
One other thing you may have trouble with, is the vibration's the 4 strokes will give you. this may cause fuel foaming in the tanks. If it does become an issue? you can blend in some WD-40. this works wonders on my twins. Also I don't know if there is enough clearance for 12 inch props. could be interesting. But swinging a smaller prop with those .91 isn't much of an option either. your engines won't load up and you won't be able to idle them down.
post pic's when you get her done.

david polley

Kahlog,

That is nice that you can program the model.

I have to fly mine old school. I know a gyro in the rudder for instance would really help on take off runs, especially off of a paved runway like I fly from, but then I really wouldn't be flying it on take off runs, and after all of these years I have finally figured out how to "oscillate" the rudder to do the work of the gyro.
I also have mechanically set the throttles to bring them up together using dubro servo guard spring assemblies.
Yes it is a pain in the rear end, but when they are set like I have them now, most folks are pretty amazed that I did not program the throttles. I guess the one thing I could really use in a programed system would be the auto trim feature that would automatically put the necessary down trim on the elevator when the flaps are engaged.
So.... I use a little flap and bring it in a little hotter now, but I believe the new leading edges I put on the model between the nacells and the fuselage have really helped on the landing approaches. The ground effect on the landing can force the plane to drop 5 feet before you approach the runway because the model just stopped flying at a really slow speed. I really believe they have helped.
Keep us posted

David

kahloq

I received the box today from nitroplanes. I have been working on an ESM 95" me-110, but masy stop and switch to the Mossie just to get it going so you all csn see.
As for prop clearance, if the 12x8 3 blades wont fit, I can use an MAS 11x8 3 blade since some of you have been using 11x7 2 blade apc props in your setups.

OR...I can use Graupner 11x7 3 blade props as they are heavier then an MAS prop and so should load the motor a bit better and also allow for a decently low idle due to the weight effect. Additonally, with on board glow, I can get the idle down pretty good I think.
Will just have to see.

david polley

Kahlog,

Here is a photo of my mosquito all dressed up at one of our our model shows. I used the 11 x 7 Graupner props for the show. They looked real nice, but I bet they make a bunch of noise if you ran them. Don't know, I have always used wood props to fly with....
and yes these are very heavy props.

David

kahloq

Looks good. Ive flown with graupner props before. They are not all that noisy until you get much bigger like the 16x8 3 blade. I ran that on an electric setup in a graupner Fw-190 D9 and it did kinda make it sound like the plane was running a fuel motor
The bonus though is because they have fat paddle blades, the develop a ton more thrust then MAS or APC props.

kahloq

Update so far....

Have dremeled out some of the wood structure in the wing center section to fit larger fuel tanks. It will be reinforced back up once the motors, fuel tanks, and assorted stuff is installed.
The tank size is 550cc's or 18.5 oz per motor. yea i know...quite big for .91 4 strokes...but its what I had lying around.

The motors will be installed using the composite plastic mounts included in the kit(normally I use H9 metal adjustable mounts).....the kit's motor mounts can be cut down to get the motor butted right up against the firewall. Will have to take photo so its clear what I mean.

Onboard glow for both motors will be handled by a 3 cylinder Mcdaniels unit that is mounted in the nose. There will be a deans ultra plug spliced in betewen the control unit and the wires running to the glow plugs on each motor for wing removal. The added length of wire for those plug cap lighters MAY require the use of a 6v rx type pack to power heat the plugs.

Retracts are Robart air up/spring down robostrut. The mount points in the wing have already been modified to accept these. The robostruts themselves are the oleo type nose fork style to somewhat emulate the real planes look. Not quite scale, but decent looking.

The flaps....Im planning on using HS 125MG thin wing servos...one per wing side instead of the L-shaped mechanical linkages per side to one main servo. Those L-shaped pieces will be used instead on hooking up the throttle linkages since the throttle barrel and carb will be right up against the firewall...a straight on shot to the throttle servos probably wont work.

david polley

kahlog,

WOW....[X(]
This baby sounds real serious. Can not wait to see everything you have done. Just make sure you beef up those landing blocks. The wood in each gear block is pretty bad.
It wont's hold up at all, and with the weight your model may come in at I believe your going to need extra strength all around in that area.... Keep us up to date....

David

kahloq

Doubt the weight will be much different then most here. I just wont be needing to add much lead in the nose. What concerns me is the thin wood used to create the internal structure inside the nacelles. Thinking of putting in some gorilla glue in areas to stiffen up the wood

The retract mounting blocks are actually pretty thick on mine, but soft type wood. What Ill do there is use some harder ply wood plates under it with blind nuts and then hex head bolts going all the way thru to the mounting flanges of the gear.

Note...this is a 73" plane....but most weights are 14 pounds or less. I have a 73" Me-109 that weighs 16.5 pounds. Obviously the cord of the wing is wider on the 109 cuz the scale size of the plane is bigger, but 14 pounds isnt worrying me. I have an 80" B-17 that the cord is LESS then this Mossie and it weighs 14.8 pounds and flies with no problem. Trying to compare different planes tho isnt that helpful as each are different shapes, different engine quantity, etc.

Anyway...back to work on the Mossie

kahloq

Ok first motor is mounted. Even with the carb being butted up against the firewall.....I am still long by 3/4" between front of cowl and backplate of spinner. I expected it.....but 3/4 is better then an inch. Ive got some 3/4" thick balsa I can carve out to make an extension on the front of the cowls and glue them and bolt them in place. They will be covered then with a layer of epoxy and then painted black.

The spinners Im using are P-38 style 3 blade from VQwarbirds. I have had these spinners forever....was gonna get a VQ p-38 until they stropped offering them here in the US due to Lockhead's crap a few years ago and never found a use for them till now. While they arent quite the right shape......they are the right diameter and most of us here arent using the right shape spinner anyway. Saves me $80 from having to buy 3 1/4" P-51 shaped spinners from hangar9

Now.....on the motors. They are mounted sideways exhaust port down. Normally, thgis would put the high speed needle facing straight down and the throttle lever on the carb straight up. Well...this is no good as the throttle lever would have stuck out from the top side of the cowl just a bit. man these cowls are small.
Anywhoo......I opted to simply reverse install the complete carb assembly(basically removed it from the motor, flipped it around...and rebolted it in place. Now the high speed needle stick straight up and the throttle lever is well within the cowl behind the cylinder. That in and of itself presented another problem though. Now I got make a crater of sorts in the firewall so the throttle lever can fully move.