Gmann6843

steve1mac

Had a tough landing last fall with my Skymaster 337. Tried contacting Nitroplanes by email, phone, several forums and got no help at all!
My guess is, if the plane is not currently in production or stocked in inventory they don't want to be bothered.
I never got a response to email or forum posts.
When I first received the model the canopy was broke into 3 pieces. I did get a response to that part request but they never shipped any parts. Just a lot of talk.
I really like the plane but we are on our own if anything needs replacements.
If any of you have received parts for a 337 I sure would like to know!


I found a very close match on a Decathalon ARF kit.
After painting and cutting for the engine and muffler it fit near perfect.

jaimefernando

This is my experience so far with my new Cessna 337. A friend of mine sold it to me ( I would say he got rid of it and now I understand why) and after opening the box initially I thought that I would have made a good deal. All seemed to be in order but once you start putting the pieces together, you realize that the kit is far from good if you compare it with Hangar 9 or Great Planes or even Black Horse. The instructions are rubbish and I can't understand how come such a company can't hire someone who could put in plain english the instructions together. This is not a kit for a beginner and you need to use your previous experience to build the complete kit. The issue of having to drill the holes that support the dowells, to invent how on earth you are going to put the wings together with no instructions at all, is just unacceptable. Do not even mention that this kit does not come with a rudder or instructions to build such if you want to.... I can tell you that this is the first and last Nitroplanes model that I buy. I am almost finished with the construction, have put 2 x 40 4 stroke (maybe a bit underpowered), lost of weight in front to compensate for a pretty heavy tail, so in a few days I will tell you how is it to fly that model with no rudder. I have to confess, I never use it anyway in my previous models, including a Top Flite 182. Let's see how it goes, but once it is finished it looks nice from the distance. Oh, almost forgot. The kit came with no pushrods and front gear (or perhaps my friend took them for another model?). Instead, they packed two sets of screws and bolts....

Sgt_Ric

I have been watching Nitroplanes and their sister site Raidentech for years, esp once I decided to buy the Skymaster 81".
It was often out of stock at either site and often both.

I followed the forums on rcuniverse and rcgroups enough to have learnt that support is almost nil for parts, etc.

As this model is perfect as a single electric UAV, I will purchase at least one more when I find stock. (there are other dealers using the exact photos and description, so it seems to still be in production)

I have come to understand the limitations of buying Chinese junk, but I realize that even if I have to rebuild many parts of this model, I am still further ahead than if I tried to scratch build a twin boom UAV platform.

It has taken me 3 years to build (at the same time as the experimenting with the diff versions of the ArduPilotMega autopilot)

Using the many tips of this and other build threads, I believe I now have a good model.

jrb1

Always liked this aircraft.

Got two events coming up MARCEE ( www.marcee.org ) and WATTS (http://www.watts2012.net/Welcome.html ) – maybe?

Fortunately the decals aren’t on so I have a bit more liberty with the scheme @ not too much work.

Big but not too much room in the fuselage – like many new ARFs the construction laser cut light ply.

As implied above, this isn’t for the faint of heart 1st time for an ARF guy – not much detail in the manual at all!

Went with a package I never tried before for the power system; was easy to order from Hobby Partz:
Tacon Big Foot 60 Brushless Out Runner (400KV)
Dynam Detrum 60A ESC
20C Sky Lipo 5000mAh 18.5V 5S1P

Will likely go with 14x10 up front and 14x12 behind.

Sgt_Ric

My single engine mod has an AeolianMotors C4260 KV500 pushing a 3 blade 16x8 pusher prop.
I had to change the the tires to much larger just to add clearance, and given the flex, I would like to replace the main gear completely with some carbon ones from a Sukoui model.

jrb1

Been doing a few things motors/ESCs/ batteries are to arrive tomorrow !

Nice guy posted some motor info for me; so. I'm putting a plan together.

Did the nose wheel servo in the nose; folks were saying it needs some weight up front:

jrb1

Got the motors, ESCs, and packs!

Motors seem very nice and run well – 2.2 & 2.5amps @ no load w/9.8V; loads tests tomorrow.

Packs seem well balanced; no charge rate info listed, i.e.: 2C or 3C just Ultimate Charge Series?

ESCs – didn’t check out correctly at 1st and there is no BEC data listed on their labels?
1st test w/ A123-3S, one worked w/CC BEC added.
2nd test w/Full LiPo-3S – one yes & one no.
3rd plugged into Turmigy Plush Programming Card and set parameters – now both worked!

Next will be mounting motors and getting ready for CG check.

Mass, Torque, & CG?

I always find the balance point of my wingless Fuselages before making a change in set-up/equipment.

Then set it back to that point after the upgrade (bigger battery, adding skis) – seems to work every time.

IIRC (more than 30years ago) from my Kinematics/Mechanic of Solids class a “force couple� (i.e. torque) can be move anywhere within its plane.

So, I’m wondering if I can use my technique Pre-Flight for positioning the equipment?

In this case I’ve added weight to my Skymaster to get the CG per plan; then found the balance point of the fuselage.

I’m hoping that I can put the equipment in (motors, batteries, cowls, etc.) and balance the fuselage at the point found above.

And, then be “Balanced� when fully assembled.

Comments!

TIA,

Jim

jrb1

Do know the Torques about the per plan CG needs to be of equal value and in the opposite direction.

jrb1

Weight of the wing/boom/tail groups is 3#-15oz; torque about the per plan balance point is 450 in-oz:

nioa

Keep up the good work Jim (jrb1),

I'm watching your build with interest. I have two of these planes sitting in the box. My plan is to install two .46 size motors, and to modify the way the wings attach, and battery compartment access. As soon as I finish my B-17, I will be on to building this bird.

Wanted to pass along some encouragement, and appreciation for your input,

Nick

jrb1

Guess I proved my 1st thought to be incorrect; but, it does works well enough when making smallish changes with a typical aircraft configuration.

Here’s my set-up to check the Fuselage: 21� >> 1# 5.5oz.

With no pack scale read 7.5oz packs need to be ahead of per plan balance point.

The found an alternative way to easily check things as I go along - - fuselage balance @ 3/8� behind the front wing former.

jrb1

Arming harnesses & ESCs installed – ran both motors too !

jrb1

The method seemed to get me close – though I think she’s nose heavy:

Weighs in a portly 13#-3oz.

jrb1

Still working on the beast!

The way this thing goes together the packs are buried and can’t be move fore/aft when all buttoned up.

To complete the datum I plan to locate the CG of the wing/boom/tail/group.

Will also go back the moment fuselage set-up; and get its weight and CG.

The I should be able to adjust the RTF CG in an exercise similar to “weight & balance� check of a full scale.

Will likely use the back of the front spinner as the reference/datum.





My 13-3 doesn't seem so bad.

jrb1

Progress!

Got CG of wing/boom/group and set up fuselage again and got its weight & CG.

Using the Back of the spinner as the datum the CG calculates per plan!


Math shows that moving the fuselage CG back ½� changes RTF back about 0.7�

jrb1

Some prop tips here; bushing/spacer is needed to allow regular APC E to be used with rear spinner.

And, washers made from sanding screen are useful too!

jrb1

Nice day for a maiden!

Moved out too quick for photog on take off, nice landing though!

[youtube] http://youtu.be/IGxYaonPKos [/youtube]

[youtube] http://youtu.be/BSl8mNH8OSI [/youtube]

Gear is bowed a bit – ugh.

Ran out of both up elevator trim and left aileron (the wing’s not parallel) – very nose heavy!

Too light on the nose wheel; so, I flipped the mains.

Maiden CG calc'd to: 125mm.

w/batteries aft all the way calc's to: 142mm going with it.

Buttoned up and ready to go again

Will leave elevator as is likely to take out all of it's trim w/new CG.

Going to check lateral balance one again and change aileron trim.

jrb1

2nd flight on Saturday; landing wasn't as smooth . Have beefed up the mains by pop riveting on some aluminum from an old set of mains.

Still needed more up trim; but no stick pressure when inverted.

Looks like I might be using a bit more MAH out of the rear pack maybe the 2" of additional pitch is a bit much?

jrb1

Maybe I’m over powered?

Another flight Tuesday – I hate these one flight and need to make a change/repair back home outings.

The take-off was great and it finally seemed be in trim; made a nice pass – cool!

Next pass weird noise – ugh.

Gotta land – needed a go around too.

Upon landing notice the rear prop wasn’t right – its nut and washer were gone; lost sometime during the flight.

Definitely before the go around.

jaimefernando

Thanks for your detailed post.

I maiden'ed my model last weekend and it didn't go well. As it is the first time I use ASP engines ( I am an OS Engines man...) they didn't run smoothly. The take off was fine but then the engines revs were up and down and after battling with model balance and trimming, one engine quit (the front one!!) so i had to land. I have to say that the model was still flyable with one engine, but I would have preferred that the working engine was the front one and not the one in the rear as it makes the model much more prone to unstable conditions. The landing wasn't that great and the front engine +firewall came apart. I have to say, I am amazed as to how strong the structure was!!. Nothing happened to the wings or fuselage and let me tell you that it was a VERY rough landing. Back in my workshop and my 337 should be ready in a couple of days for the second attempt, windy dependant.