Patto

Yeah, the screw holes are there, and I'm not even going to be using them, after all that. I'm putting the screws in the outer panels so that there are less pieces to transport and the tail booms have the extra security of the center wing panel while off the plane.

I finished cutting up the once beautiful cowls today. I mounted them and verified I can put a glow-starter on with them there. I did some programming with the radio. I'm trying to figure out how to use channel 7 as a slave channel for the throttle and have the switch it normally uses inhibited. Not sure if it can be done.

I installed the wheels and found that the nose gear is thicker than the wheel collars, so I basically had to bore them out with a drill to get them to fit. Same with the nose wheel.

You can see in the pics I've got the inside of the fuselage set up except for the front fuel tank and windshield. I'm anticipating the plane being tail-heavy from what I've read and observed building it, so I put the battery up front under the place for the fuel tank. Therefore, I'm waiting until I balance before I go to all the trouble of installing the tank and hoses. I'll fit and mount the windshield after I mount the wing.

I glued the horizontal stab into the tail booms. I used CA for this and I'm not at all worried about it coming apart. I flowed some medium in there, (after cutting away some covering) and it feels nice and solid. Not to mention the tail booms aren't going to let it go anywhere regardless.

The vertical stabs are in place. As you can see, I tore the original covering off and I have one re-covered. It turns out that the balsa is closer to 3/8" than 1/4" as my ol' buddy Spydermonkey said... No matter, I'm not too concerned with a little "rib" effect. At this point, I want to get it done and fly the darn thing!!

Patto

YOUR MISSION - IDENTIFY THE BUILDER'S MISTAKE IN THIS PICTURE:

Patto

We'll see who's the first to identify the mistake I made. Hey, I'm not a master-craftsman/builder. I never claimed to be, and I make plenty of mistakes while putting together the most simple airplanes. This particular airplane has tried my patience a few times due to the lack of instructions, but I'll reserve judgement for now. Based on the quality of the kit alone, it may be a little over-priced, but not by much.

TOTAL TIME INVESTED SO FAR: APPROXIMATELY 17 HRS

Today I finished covering the new vertical stabs and rudders. I then hinged the rudders and elevator. After that, I epoxied the wing tubes to the main wing panel and tail booms, making the airplane a total of four pieces to transport to and from the field, (fuse, booms/main wing panel, & 2 outer wing panels). I also epoxied small pieces of hardwood into the exposed ends of the aluminum wing tubes for screw retention.

I went against my better judgement and installed the front fuel tank and fuel lines while the glue was drying. I was going to save it until the end since the tank will rest above the battery and I'm not sure where it's final resting place will be. But, I'm trying to shorten my to-do list.

I also set up the linkages on the wings today.

TLH101

My Feedback: (90)

Flap horn? Found out that flap servos need to identical, not mirror images. You can use a reversing "Y" and get away with mirror servos.

Patto

Terry wins =) It actually still works but I'll end up re-installing the flap's control horn before the maiden, just in case.

TLH101

My Feedback: (90)

Been there![&o] What does I win?

Patto

You have won a year's supply of... nothing!

Patto

After all that hard work, WE HAVE A PROBLEM!!!

I deliberated long and hard about the wings and, eventually, decided that it would simplify everything if I just epoxied the whole wing into one piece. One problem I'm seeing with this aircraft's design is that in order to take the main wing panel off, you have to take off the rear cowl. That, to me, is a big hassle. I will most likely transport it in one piece.

I discovered, after I epoxied the wings onto the tubes, that the left wing sits about 2 1/2 inches higher than the right. It looks like it may actually have more dihedral built into it. It is also possible that it's the landing gear not being completely symmetrical. I was too tired and I ran out of time to delve deeper into the mystery.

I installed the elevator and rudder servos. I decided to use one servo for the elevator, since I'm using a digital on 6 volts, and one for both rudders. They will be linked by a rod between them when all is said and done. That's actually one of the few tasks I have left.

This airplane has been somewhat of a headache to build. The instruction manual was near useless and I just stopped using it awhile ago. That was especially frustrating when dealing with the wing mounting issues and various other details that left me asking, "how do I do this?" If this wing issue ends up being serious, I'm not sure how I'll repair it. I may have to get creative again.

In the pictures, please ignore the mess in my garage. I'm running out of space in there with all the airplanes!!

fearless fly

Hi PD, "mess in my garage".You must be joking .You've got a long way to go before you can equal my "mess"

Cheers,
Fearless.

Patto

Hey Fearless, at least your "mess" consists mostly of airplanes. Seriously, look in the background, my garage is overflowing with all sorts of things! Before I start on my next airplane project, I'm going to clean so that I have a workspace to build on.

Spydermonkey

Hey P,

Good work on the rudders! I see from your pic's that we're about equal on the build. I said that I was going to try to fly mine last weekend but, will it was a beautiful weekend! ALL SNAFU, to say the least! At least you have a garage to work on your plane in, try the kitchen table! well it's good that your build is going good, but to save a little time and money, mount the flap servos in the same direction, and mount the control horns on the same side and this will work instead of using a mirror. (i.e. mount the flap servos with the gear toward the leading edge of the wing and then mount the control horns toward the right wing tip) good luck B

Patto

Hey, so you said "ALL SNAFU", does that mean you didn't fly or does it mean you did fly and then things were SNAFU'd?

Yeah, this is actually the first time I've had an airplane, that I've put together, that had flaps. =) I don't usually build scale aircraft, but this one I just HAD to have... Now, I'll know for next time.

Spydermonkey

Sorry it took so long to reply. SNAFU well it was a good weekend to fly but things around the house caused the SNAFU! Have you made it to the cg bit yet? I just found the cg on the bird, and the use of a little bit of weight is an understatement! I'm running two 6v batteries and with those shoved in the nose beside the tank, I still had to add a 5oz spinner weight and 10oz of stick weight! Can we say !QUOT!Flying Boxcar!QUOT!? if you or anybody has any ideas to solve this problem please share. If I find a better way I'll pass it on! Brent

Patto

With those tail booms out the back and the servos mounted that far aft, I had a feeling I would need to add some weight. It ended up being about 10-12 oz., as it turns out. I am using one 6V battery, stowed under the forward fuel tank. The rest of the weight is sitting on top of the firewall/engine mount box up front.

If I had thought ahead more, I could have mounted the elevator and rudder servos toward the front of the booms and routed some pushrods inside the booms to help alleviate the balancing issue, but oh well... I should have enough power regardless.

This Sunday is the set date for the maiden flight. Wish me luck...

Spydermonkey

Well how did it go? I've found a slight problem in tuning my 46's. Apparently by running the same props front and back, it created a vortex that wouldn't allow my rear engine to time in. I put an 11x7 on the front and the rear ran fine, even with out the muffler! Darn bolts! I hope that you did get the chance to fly it today, and I'm looking forward to reading about your post flight and your setup! B

Patto

The Oregon weather decided to foil my plans, once again... It's probably for the best since I discovered an issue with the rear throttle control while I was doing one more final pre-flight check. Apparently when you "null" the slave channel in the P-Mix of the 7CAP, it changes the throws of that servo. It was weird, but eventually I got it figured out.

One major flaw in the design that I'm finding is that taking of the wing is a huge, time consuming chore. Oh sure, it bolts on easily enough, but you have to take off the rear cowl in order to get the wing off at all since the air scoop covers the bolts and is in the way of lifting the trailing edge up. So, you have to take off the rear spinner, prop, needle-valve extention, and cowl. Then, you have to unscrew the struts. THEN, you can take off the wing, and you have to unplug the wires to the six servos.

My suggestion to the manufacturer, regarding that issue only, (there are many, many other suggestions I would make!!) would be to have a wing bolt plate in the front and rear of the wing saddle and get rid of the leading edge dowels. Then, you can just make two holes in the rear cowl to unscrew the rear bolts. You would only have to remove the windshield from the front and you're done.

I'll post when I get home from the flying field tomorrow, assuming the weatherman was right when he said it would be decent outside tomorrow...

So, Spydermonkey, did you end up getting to "maiden" your 337 or did the engine issue keep you grounded?

Spydermonkey

Murphy was riding shotgun on me too! About the wing issue I built a PVC rack with my friend to hold my plane in the bed of my truck. Still got a little work to be done to it, but it'll work nicely. On the throttle servos, I just used a Y harness to do the job. Its simple and easy, but being that the wing is already in place no since in moving it around now! hope to fly today too! Good Luck!

Patto

I went out to the flying field yesterday, Memorial Day, and had a lot of good company since a lot of our club members had the same ideas for the holiday. In the back of my pick-up, in its custom-made PVC carrier was my Nitro Models Cessna 337 Skymaster, out for its maiden voyage into the wild blue.

There was no wind. The runway needed to be mowed, but with two 4-strokes, I anticipated that to be a non-issue. After firing up the Magnum for the first time, and it started right way, I started the O.S., which had about 1 hour of run-time on it in a different aircraft. Both fired up with no problem, although the O.S. seemed a little rich on the low-end. I ran the Magnum rich all around since it was new.

With two helpers, one on each wing, the 337 was lifted off the bench and set down on the edge of the runway. A little engine run-up, a little high-end adjustment, and I ran out of excuses to keep her on the ground. I put the controls on low-rates, conducted one final surface check, and taxied onto the runway. I wasted no time and put the throttle to the firewall. The Magnum came to life instantly while the O.S. lagged behind but slowly gained RPM's. The 337 lumbered in the tall grass but, at about 25 MPH, began to lift off with some elevator coaxing. It sailed gently into the air and needed only slight aileron trim and moderate elevator trim. On the downwind leg, I felt confident, and the 337 looked great! I decided to tempt fate with an aileron roll and watched as it rolled much more on the axis than I had ever imagined. I heard people talking about it immediately: "Look at the way it rolls!!" No one could believe it.

The rudders showed to be near useless, but better than nothing.

I landed with the nose up, flaps down, and it was absolutely beautiful. Here are some pictures of us at the field...

Spydermonkey

GOOD JOB! glad to hear that you got the 337 up. are you running the same size props on both engines? and what are your throws? Once again good job on your plane

Patto

Spydermonkey,

I used a 12X6 Topflite pusher in the rear and a 13X6 MAS in the front. These are both on a trial basis. Once I get both engines running consistently, I'll try some others and see what happens.

As far as the throws, I never measured them. I just eye-balled them and threw in some expo on the 7CAP. I also had low and high rates programmed.

My final thoughts on this aircraft are to follow...

Patto

MY FINAL THOUGHTS

To sum up my experience, here is how I feel, looking back at my experience from ordering to maiden flight:

I ordered the Skymaster online from www.nitromodels.com, used a credit card to purchase, and received it promptly within about 5-6 days, (about the same shipping speed as Tower). I paid $229.00 + shipping, which I believe was $25, but don't quote me on it... =)

This aircraft arrived neatly, professionally packaged with quality construction written all over it. In fact, I felt it was well above average for a China-made ARF when I started to build it. The fiberglass cowls were painted very well and when I had to make cut-outs for the engines later on, the paint held up without flaking off.

Now, the instructions are nearly useless: the grammar is very poor and many words are misused, making it difficult to understand what the author is telling you to do. Also, several building steps are left out and pieces are left over at the end.

I used two .70 4-strokes in this aircraft, by two different manufacturers, which is a "no no" with any other type of twin. However, in this push/pull set-up, there was no reason not to use engines that may have a slightly different output.

I elected to make some modifications to suit my needs. First, I cut out rudders in the tail fins, (it comes with no yaw control, except with the nosewheel on the ground). I used one of the servo cut-outs in the tail booms for a standard digital servo on 6V to control the elevator and a second one on the other tail boom for the rudders, which were connected through the middle by a wood dowel.

Additionally, I epoxied the wing tubes in place. The instructions do not address how to install the wing tubes, so I improvised and I was planning on transporting it in once piece to/from the field to begin with. Taking the wing off is a chore since you have to remove the rear cowl to do so. You see, the wing seats by sliding it forward with two wooden dowels in the leading edge. Then, you screw it on near the trailing edge with two 1/4-20 nylon bolts. It would be easier if it were attached using two bolts in the front and two in the rear, then you could drill holes in the air scoop of the rear cowl above the bolts to install/uninstall the rear bolts and slide the wing forward and off to remove it.

This ARF took a little longer to complete than a .40 size sport plane. Why? It's a twin-engine scale aircraft with a lot more details to work out. Overall, it went pretty smoothly for me, and I am by no means an "expert" builder. Yes, there were some snags along the way, but this is a new design from a relatively new manufacturer and there are always ways to improve on the first designs sent out. So, hopefully, the distributor, Nitro, will read this thread and make the changes I've recommended to make the aircraft even better for future customers.

Flying: this aircraft will pleasantly surprise you! It has a fantastic aileron roll that had people in awe considering it's modeled after a Cessna! The flaps worked fantastic to bring it in for nose-high, gentle, slow landings every time. While up a few mistakes high, I stalled it and tried to spin it but to no avail. It mushes forward and resists the urge to drop a wing, just like a Cessna should!

If you have always liked this twin's design and have pondered getting one, well, I think you'll be very pleasantly surprised by the way this airplane performs! It's found a permanent home in my hangar!

fearless fly

WELL SAID P-DIDDY!, this post has been a very interesting one to follow. I'm glad she turned out as nice a plane as you hoped. As you said,"I'm not an expert builder",but I reckon this build will help to make you one with,I'm sure, more builds to come.
Exellent photos,as they say,"one picture is worth a thousand words".
My KMP 337 is not far from maiden,and will post results along with pics soon.
Please keep us up to date on any mods or adjustment that you may have to make.
Again well done.

Cheers,
Fearless.

clifford

P-Diddy,
Congratulations on the maiden...lovely looking model, and at a nice manageable size too!!.....I might be tempted to order one...and re-cover with a camoflage scheme!!!!!......would two 61 four strokes fly her?

Cliff

Patto

Clifford, I think two .61 four strokes would be plenty. The .70's I use give more than a scale power amount, to be sure, even though the rear engine is probably closer in power to one of your .61's.

On that note, I just got back from the field. There was about a 5-8 mph crosswind, but I took off without fear knowing that the Skymaster can handle it. Let me tell you, it was a fun time. The O.S. FL-70 actually started the day running pretty well. I can't seem to get it to lean out on the low end and still run even a little bit reliably. The tank is below the needle by about 1/2", so it really shouldn't be flooding. I'm pondering sending that engine back. I landed twice today with it having quit. The Magnum, on the other hand, is a freakin' powerhouse! That thing is just barely breaking in, and its power just keeps getting better. It is louder than the O.S. by quite a bit, but it's worth it considering how much better it runs. It idles very reliably, mid-range is smooth to run in and transition through, and the high end is significantly more powerful than the O.S. Now, it does consume quite a bit more fuel, but I'm okay trading that fuel for a decent run.

I had some excitement today when, on the first flight, both engines were running great and I was doing touch-and-go's, one after another, with flaps and without. I took off on the last one and the Magnum got some air bubbles due to the fuel level getting low and stopped when I was climbing out at a high attitude, about 30' in the air. I nosed forward to level flight and circled around, with the flaps down, still able to climb slightly! I landed without incident and fueled it up for the next flight =)

Seriously, this airplane is a heck of a lot of fun. Sure, it can't fly inverted for very long and it won't do any 3D maneuvers, but it is a fantastic sight to see in the air... and it has a VERY UNIQUE sound, (when both engines are running).

I really love this airplane!!

clifford

Hi P-DIDDY,
Thanks for that...I wonder would Nitro Models ship to the UK??...I live in Northern Ireland....maybe will drop them a quick line!!.....you sure sound very pleased with your model !!.....the engine issue you have...for years I was under the impression that nothing ever would touch OS engines...BUT...times have changed....and I for one would"nt hesitate to buy a Magnum...or ASP Fourstroke!!...
Also...I"ve a planfor an 80" ME110....for two 60"s [f/strokers!!!!]

Cliff