Hobby King SBACH 342 1000mm v2: Take 2

I have detailed my experiences with the Hobby King Sbach 342 1000mm v2, which recently ended in the first ones demise from a dive it could not pull out from. I ordered a new one, and have completed its build, with a couple of modifications. It is powered by a HeadsUpRC PowerUp 15 1000kv 550 watt motor, turning a 11x5.5 APC eprop (to start), an Art Tech 40A ESC (salvaged from another plane), and will fly with 4S 3300 mAh 30C battery. She is only slightly nose heavy, her all up weight (AUW) is 2.75 lbs (1250 gms).

One of the problems I had with the original is I tossed my canopy in flight into deep woods, and Hobby King doesn't stock replacement parts. I added a magnet and washer to a set of opposing crossbars. Makes big difference!

I wanted to fortify the firewall since my first one caved in on a blade strike after going head over heels in bumpy grass on a landing. I placed two cross bars of popsicle stick wood behind the firewall where the screw holes would later go for the larger mount for the 15 size motor. One is on top behind the front lip of the firewall, and the other on the bottom. I like to coat the frame in what nitro guys use to fuel proof the wood: 30 min epoxy thinned with a splash of alcohol, painted on with a brush, after using CA on all the major joints. I paint anything I can see. Light and strong! I also put Gorilla polyurethane glue in the wheel box to strengthen it.

I have always thought the tabs for the cowl were very wimpy. I placed a piece of that ever useful popsicle stick wood cut to fit behind each tab and CA'd it not just to the existing tab, but also to the fuse itself. I used the method I describe in my build post to set the position for the screws.

I wanted to use mini servos instead of micros for the rudder and elevator, I think the 9g servos were overwhelmed by the aerodynamic forces in a high speed dive. I Dremel'd out more space in the existing servo tray, and placed on top of it popsicle stick wood cross bars to allow me to secure the JR MN-48 mini servos. This went perfectly! These are a little slow (I think 0.18 sec/60) but have great torque (3.5 kg), compared to the 9gm micro servos (about 1.5 kg torque). I prefer the faster Hitec HSG 225mg servo, same torque, faster, around 0.12 sec/60 I think, but I have these MN-48s because I replaced them on my Eflite PulseXT 25e with the Hitecs.

The packers cut the tip off the sticker for the canopy... I used a piece of white sticker I have laying around, you can only tell up close.

As seen here. Can't tell!

To accommodate the 4S battery, which fits inside the cowl and ends at the carbon fiber wing tube. I added a couple of pieces of light balsa to make a bed, over which I put a piece of Dual-Lock Velcro. It sits at a slight slant, and is secured further by two pieces of standard Velcro wire ties.

All done!

I really don't like the look without the wheel pants... The number 2 a tribute to its being my second one!

One of the build issues was this gap under the wing (smaller on top). It clearly was a wing tube that was cut too long. I sanded off about 0.5 cm and everything went back flush. I saw some of you had this gap problem; check your wing tube!

I really wanted the wing pants to work out. I am using a bigger tire, I think 1.5 inch. I could not figure out how to get these pants to work with the first plane. I tried a couple of different approaches, and came up with a way I think pretty ingenious and stable!

I cut a small slit in the plastic pant with a Dremel cutter, and slipped it over the strut. I then installed the wheel and pulled the pant down into place. I had previously Dremel sanded out a notch, and enlarged the wheel opening to accommodate my larger wheel. I set it where everything cleared well, and CA'd the pant into place. Between the hold from the slot and the CA its very stable! There is a wheel collar between the strut and the wheel.

View of the electronics bay with a 4S 3300 mAh battery in place. You can see the battery is partly tucked up under the motor cowl forward, and stops just short of the wing tube aft. This puts the CG just a smidge in front of the wing spar which runs about where the light glare is (the tube is just aft of CG). I am using a Spektrum AR600X receiver this time (had a HK Orange and satellite in the original). You can also see the MN0-48 mini servos in place. Plenty of room. In maiden flights I prefer a bit nose heavy plane.

I thought I had a pic of the 15 size motor in place, but I don't. I wanted to show the smaller standoff in place, so I took this pick through the right air hole in the cowl. The 15 is 10mm longer than the Turnigy 480 850kv I originally used, and pretty much the same diameter, maybe a couple mm more. Fits fine!

I am really excited about being able to maiden her tomorrow! As always, nervous about how she will handle. As I noted I propped up to an 11x5.5 (up in length, down a bit in pitch). I may try a 12x8... Exciting stuff! She has a whole lotta power! Maybe I can get a watt meter on her later. More to follow!

UPDATE: I wanted a little more freedom with moving the battery to adjust CG, so I made a couple changes:

I removed the long additional balsa to allow clearance in inserting the battery from behind the first spar (the cross wood over the wing tube) and put Dual Lock Velcro in the tray in its place. Before I passed the battery into the cowl then slid it aft under this spar. Now I bring it in aft of that spar. I had to remove the top of the second spar (over the receiver) to make it easier to clear. This allows the battery to move aft towards the receiver. More flexibility! I also cut a vent opening on the underside just forward of the tail wheel. Theres's a small framed area there that I cut an X in then ironed down the sides of. This allows air to flow, and pressure to be drawn out, increasing cooling, and reducing pressure trying to pop off the canopy.

Take 3: Eflite PulseXT 25e

I have long written about my love affair with this plane. I also had the sad duty of reporting the loss of the first two... The first was due to a radio problem (I suspect a bad NiMH transmitter battery), and the second due to pilot error (fying with my head up my ass... pulled out of a dive too late). I completed the third one day before yesterday, the build a couple of days ago, and finally when Horizon Hobby sent me a replacment canopy (the one in the box was cracked, HH sent me a new one shortly after I called asking for one). Yesterday I maindened her at BMF, and as expected she flew wonderfully!

One thing I changed was the aileron servos, and I may change the rudder and aileron servos as well. I had JR MN-48 mini servos in all four places. I changed the ailerons to Hitec HSG-225mg. These are much faster than the JRs, which I have always felt were slow.

So, back in my hangar, always a joy to fly!

Lucky me...

Well... I think I am done with the CopterX 450 4-blade head. I was never thrilled with the screw as a feathering shaft into a hollow aluminum head. I suppose some variation of this is used on all multi heads, but if I try it again it will be with a higher quality head. While hovering it today trying to figure out why my BeastX is misbehaving the head threw an intact blade with its grip across my lawn, 90 degrees from where I was standing, some 30 feet. It would have hurt if it hit me, but not too bad I think. The force of the imbalance bent the mainshaft and loosened all the remaining grips, bending their screws. The grip that came off can't be secured snug as the hole in the rotor head is stripped...
I have that bargain head coming, but I plan on replacing it with another Tarot 450 FBL head. I'm thinking of moving the BeastX to the Frankenheli with the good Tarot head on it. Maybe tomorrow.

Or... maybe I'll get one of these?

 

 

Tarot 450 Flybarless Rotor Head

I purchased a Tarot 450 Flybarless Rotor Head from CNC Helicopter, along with a Tarot ZYX 3-Axis Flybarless gyro, with which I am having a few issues. This rotor head is the best I have found at one helluva great price. I will buy this one exclusively from this point forward! In this blog post I take it apart, inspect, grease and Locktite it, then install it on my Frankenheli 450.

The head comes as seen here, without the control rods.

I took it apart. It uses the standard Align feather shaft arrangement on a 4mm shaft. I realize now that I failed to measure the length, so I can't say its a standard length, but given the design is otherwise that of an Align head, I don't think its anything but standard. I am soaking the closed ball bearings in silicone oil.

I love it when designers keep things simple. Here are the four closed ball bearing, all the same size!

Here in profile.

ip

One inside the grip.

One bearing on the head side. You can see the grip control horn here.

 I removed it and Locktited it; it has a short segment that is threaded, that inserts into the control horn, and it all screws into the grip. I Locktited both ends. Screw everything snug, but not gorilla tight. 

I used to use white lithium grease, but it dries and cakes up. I like TriFlow red grease on the thrust bearings and a little on the feathering shaft. I use silicone oil on all bearings and moving surfaces.

The thrust bearings have two sides, one side with a flat surface, the other concave to hold the grease. Grease the whole thing, but when you reinstall it make sure that the concave side faces the main shaft so that the centripetal force will not pull the grease from the bearing. Remember that there are tremendous loads on the thrust bearings in flight.

Make sure you get the order of the parts correct: screw (a little Locktite, remember just a whiff and keep it out of the bearing. Grease inactivates Locktite, so don't mix them), small washer, back thrust bearing plate (remember that with both sides of the thrust bearing keep the raceway, the bearing groove, against the bearings), bearing ring (concave side to the shaft), inner thrust bearing plate, thin larger washer.

The dampers are quite hard. A little grease.

A thrust bearing set about to be installed onto the feathering shaft.

The head is well constructed. In addition to the Jesus bolt (just across from my thumb), it has two screws, one on each side, just across from and under the swash stabilizer arm. The bottom hole of the rotor head is split allowing these screws to bring the sides tightly together on the shaft. The cheap ones often need to be stabilized as the Jesus bolt can't keep the head from teetering on the top of the main shaft. I like the long body and these tightening screws, great design.

The head all put back together. I always hold my breath when I tighten things up expecting things to bind, but everything remained smooth and snug!

One of the shaft tightening screws. I removed these and the Jesus bolt to install the head on the main shaft.

Removing the Jesus bolt.

Installing the rotor head onto the main shaft. In a moment I will realize I have the swash stabilizer arms going the wrong way and will remove them, spin them around, and re-Locktite them in place...

All installed with control rods in place. The gyro stand is empty awaiting the replacement Tarot ZYX 3-axis system to be installed.

This Tarot 450 FBL Rotor head is well constructed, well designed, tight and easly installed! Can't wait to put the FBL computer on and wind this thing up!

Tarot ZYX 3-Axis System: Strike 1

Last week I was chatting with Dick Ober, MCRCC club prez about my BeastX heli and how much I loved it. He mentioned he had bought a Taro ZYX FBL system and it was being installed and programmed for him by someone, on his Align 250. I had never heard of it, though I am familiar with Tarot. It is a FBL computer that is about $70! About 1/3 the price of the BeastX. So...I checked out the Tarot ZYX system online and it seemed to be well received. I was a bit worried about programming it, the way it was designed compared to the BeastX, whose programming is very easy, but this vid made it seem rather straight forward. I ordered a Tarot ZYX 3 Axis FBL system from CNC Helicopter last week. They are a quick shipper of great products, and I have ordered a lot from them. At the time I ordered just the computer, but later that evening found the generic FBL head I had ordered on eBay was a POS (I had another one just like it that was a great head, so this was a surprise. Looked fine, I took it apart and could not get it back together without binding as the feathering shaft seemed short: There's something screwy with either the grip bearings seating or the whole thing), so I went back to CNC Helicopter and ordered the Tarot FBL rotor head. I should have ordered both at the same time as was kinda hoping that CNC would give me the package price with a refund (I didn't ask for it, but they sent both in the same mailing bag...), but they didn't. Oh well, my bad.

The kit arrived yesterday, quick shipping! I checked it out this morning and noticed that the set button was a hole... I passed a paper clip and it met no resistance, nothing there. I tried installing it. I connected the ZYX to the receiver only, with the provided cables, turned on the transmitter (I had zeroed everything) and powered on the heli, then held the aileron stick left or right (tried both), all three lights came on, and the went out, and the red light came on steady. It never went into programming mode. I tried several times. So, no set button, but it didn't matter because it never went into programming mode. I even tried using the rudder stick.

This is a big disappointment. I contacted CNC Helicopter and am waiting to hear from them. I wish they had a phone number... but had to settle for an email. I suspect they will have no problem trading devices, but this is going to eat up another week or more!

I like the Tarot FBL Head on first inspection. I have to take it apart to grease and Locktite it, but this thing looks very sturdy. Unlike most FBL heads, the swash stabilizers are connected directly to the base of the head instead of on an adjustable link that is secured to the shaft separately. Positioning the adjustable heads isn't difficult, but one less thing to come loose.

I was pretty excited when it arrived. I wasn't sure that the whole low price-low quality curse would apply as Tarot makes very good Align compatible parts, like that remarkable FBL Head. I am a little more skeptical how this is going to work out, but really want to give it a try!

Keep tuned for updates!

UPDATE: Within a couple of hours XMHobbies/CNCHelicopter has a new one on its way. Running out now to mail them back the bad one. Stay tuned. Thanks, Jeff, at CNC Helicopter! One thing I didn't mention until I remembered to email Jeff about it... When I opened my box the device was "missing" having fallen behind its holder and was rattling around in the box. I wonder if that's how it got damaged?

RC Pilot Magazine

I received a promo email from Tower Hobbies about the newly launched RC Pilot Magazine, and thought I'd check it out. After going through the premier issue, available for free, I easily decided to subscribe. A project of Michael Kranitz, one of the cofounders of RC Universe, this webzine is amazing in its premier issue, and has three other issues since. In the premier issues I found really well written pieces exploring the personalities of our hobby, pilot, airplane, and heli stories, videos that a expertly done, with beautiful photos, in a format that is designed well for the screen. RC Flightdeck lists on an intactive map dozens of fly in's, rc events and shows, with information about each, and when needed online registration for the event. Even the ads are fun, many production videos by manufacturers (loved the short one for Realflight!). This clearly is designed from the ground up as an interactive experience. From what I have seen so far this is hands down the best emag out there. Period. Eye candy, brain candy, and rc addiciton fix! Every page was another wow!

As I write this the current iPad app (you can read the mag on a computer too) allows me to download the issues prior to April's issue, which requires an updated app that Michael tells me is done, awaiting final approval by Apple, and is expected to be released soon.

Get a subscription now and get a free RC Pilot T-shirt! I got the thumbs one coming.

 

Cornell Died-ed

Level flight, total electronics failure. Slow right roll into a high speed dive into the Southern Ents. The breast of the wing is 30 feet up in a tree with part of the wing, the other is missing. No idea where the receiver is. Recovered the tail in a bush beneath the tree, the nose beeping 10 feet away. Buried in the toxic effluent from the waste dump that our field sits on. Into which I sunk knee deep to recover these pieces. After forging through the poison ivy. And avoiding the rattlers. Afterwards, no ticks.

Curiously, I don't give a shit. It was jinxed from day one. I'll salvage what I can of the electronics (saved the pack) and when I get the itch, I'll build the NIB one.