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Posted by SkyCadet | Feb 10, 2013 @ 08:56 PM | 3,884 Views
For those on knifedge coming here, sorry, but the zip file is over the 500kb limit.

Here is the file of a 1250Kv, 3536-6 500W RCTimer motor

SkyCadet
Posted by SkyCadet | Jan 29, 2013 @ 11:48 PM | 3,989 Views
Taking the mystery out of expo settings on radios --- finally!



Did you ever wonder what those functions actually were that set the "expo" for your radios? Well, wonder no longer!

These are actually CUBIC functions that are symmetrical about the y-axis (relative throw) and are designed to either reduce or enhance response up to full throws.

After some digging, here is the formula!!!

y = rx³ + (1-r)x

Where:
x = control throw (stick position) amount. -1<x<1 for most radios;
r = the exponential rate setting in decimal equivalent of %.
(so for example, 25% expo = 0.25, and x = ±1.00 for full stick movement)

I have verified this result with two sources: One on the net, and another with software - Real Flight expos do the same on expo rates on models.

So, what does this really mean? The higher the expo, (above zero), the more dead band we find in the center of the stick positions - this IS useful to linearize a model's deflection of control surfaces. Did you think that throws are linear? Nope, not quite. The SERVOS are, in angle versus input from the sticks, but the movement is actually the SINE of the angle. I have some data below that illustrates what the relative motions of the surfaces behave for three angles: ±45°, ±60°, and ±75°.

±60 degrees is the normal throws at 100% for most servos. 75° is a 125% setting on control throws, and 45° is at the 75% throw rate.

The reason this is important to consider is that...Continue Reading
Posted by SkyCadet | Jan 09, 2013 @ 03:05 AM | 4,761 Views
My buddy ordered a backlight 9X kit the same time as mine, but he had not been in town until today. He brought by his DX7s (also requiring a backlight) and we installed it today!

It turned out superbly! See pix below. same basic deal as the DX6i, except the power is tapped off the positive lead off the vibration motor (to pin 2, the outermost pin on the connector left, fifth from the black lead on the 9X's connector plug) and the negative goes to the furthest right pin on the back of the radio (rear half board) (to pin 3, the innermost remaining lead).

See helifreak's DX7s backlight mod. (google it). Also, I left the heat shrink on his 9X connector, whereas for some unknown reason, HF took his off.

His install also made a slightly brighter white screen on the right side. I avoided this by using thin 1/16" foam double sticky tape on the board, and then the panel stuck to it. I then epoxied the main display edges (like I did on my Dx6i) to the panel, and added some foam sticky material that came with the 9X kit (~3/8" wide) on the exposed remainder of the panel that is past the right side of the screen (like I did with the 6i mod below). this acted like a spacer to avoid screen damage, and also hides the uncovered bare panel from creating inner reflections leading to a brighter right side (see HF's pix). Ours turned out perfectly!

Also used a Radio shack 4xAA flat AA holder with a cordless phone plug to allow either the stock NiMH pack OR 4xAA (NiMH or Alkaline) to be used in the TX! See pic below. Removal of the foam inserts allows a clean fit to this mod!
**make sure to reverse polarity on the plug - Spektrum has theirs opposite for some reason!

SkyCadet
Posted by SkyCadet | Jan 05, 2013 @ 01:19 AM | 5,158 Views


Can you tell I am happy?

Finally! I love my DX6i, but reading the display and not having the ability to read it under sunny days well, or at dusk, really sucked!

I have some photos of the 9X backlight kit I got from HobbyKing. These are $5, and well worth the $$. My DX6i is a great radio, and having used it with many of my models, I wonder why Spektrum left a backlight off the unit in the first place! The 6i TX is sometimes all one needs to fly a 4-5ch plane.

Took about 30 minutes total. I had to epoxy my display due to the issues with solder tails left too high on the circuit board preventing the use of hot glue easily or double-sided sticky foam tape. As you can see in the photo below, the display is crisp and clean - finally! Spektrum better start to add this as a feature in ALL radios moving forward. No excuses.

Notice I also added a swiveled extension for balancing the radio better using my neck strap, and wider thumb stix. both work well, got them off eBay.

DX6i Backlight install using the $5 Turnigy 9X Kit (18 min 35 sec)


This video is 18 min long, and the fellow does an excellent job of showing how to do this mod. not hard, and only one solder position to make work!! I highly recommend this. All one does is to remove the jumpers off the bottom display board, pull off the TX module, remove the display and put the 9x display under the glass display. Affix however you can, and BINGO!

SkyCadet
Posted by SkyCadet | Dec 18, 2012 @ 12:06 PM | 4,392 Views
While the weather is not entirely ideal for flying right now, I have always wanted a backlight system for my DX6i. My friend has a similar issue with his DX7s.

We ordered some 9X Turnigy backlight kits from HK, and will be putting them in when they arrive. I'll post some pics and maybe a vid or two of the procedure for those interested. It looks very easy to do. Stay tuned! The mail should arrive around just after Christmas, maybe sooner!

Skycadet
Posted by SkyCadet | Dec 17, 2012 @ 10:19 AM | 3,641 Views
Well, it warmed up a bit this weekend, and I was able to fly my Super dec BL on skis, but the wind chill was near -5F!!!

Getting waaay to cold for this ol' flyer to enjoy the skies with those kind of conditions, so I am practicing my flying with RF 6.5 whilst I await the new batteries for the Yak 55 from HK. They MAY just even make it in time for Christmas...

Skycadet
Posted by SkyCadet | Dec 07, 2012 @ 08:31 PM | 3,843 Views
Just finished putting on my new polished aluminum 2" spinner!

all looks good!

Just some wiring tidy up and we're ready to maiden.

SkyCadet
Posted by SkyCadet | Dec 07, 2012 @ 02:12 AM | 4,246 Views
Below are the pictures of the new Yak 55 sans spinner (stuck in the mail still!)

But all the hookups are done. Just have to clean up the wiring a bit, and figure out a few layouts for batteries, and fully attach the wings.

This plane has a LOT of throws on the control surfaces, so I set 50% for low rates (63% actually, 1/2 of the 125% I'm running the servos at on high rates).

This plane's color scheme and layout are truly superb, IMO. I really love the color scheme and format, and I am very proud of this model with the extras I put into her, such as the vanes, and CF gear. It really looks cool on there, and gives a very stable stance now to the plane. I'm SO glad that I did it...

Dry empty weight with no batteries is about 34.5oz (975g).

Comments welcomed. I am not sure exactly when I can maiden her, as it's very cold (-18C) and very snowy. Probably a few weeks before I may be able to take her up.

*I am also deciding on battery layout - this plane's CG sits right about where the main wing joiner tube fits, 85mm aft of the wing leading edge. However, I have NO way to fit standard 2200mAh batteries in her, as there's too much cross member and stuff to permit it. Further, even if I could, I'd probably need about an extra 30-50g minimum in the tail now to balance her out. Yes, the vanes and CF gear probably added about 2oz total, but the joiner tube is sort of in the way (but has to be there!). I'll figure it out, probably 2x 1300 30C 3S Lipos in parallel.

Sky Cadet
Posted by SkyCadet | Dec 06, 2012 @ 12:25 PM | 3,860 Views
I finished connecting and centering the servos/horns, and installed the motor mount into the fuselage.

Final test fit of the cowling prior to adding mount screws, and the plane looks VERY nice, if I do say so myself! Below are two shots of the plane minus wings (easier to finish electronics layout without them on the plane for now), showing the vane system and prop as it will appear when I am done.

A static motor test the other day on the RCTimer 3536-6 1250Kv, 500W motor running the MAS 11x7 3-blade prop had around 330W peak on WOT with a nominal (not fully charged) battery, running just under 37Ap. 50% ran around 130W at 11.6-11.7A. well within the capaibilities of this 3S system, and some room for tolerance on the power system (ESC is Turnigy 45A/55Ap unit, so I am safe).

The only odd thing was in order to get close to the 40 degree throws in the manual, I had to run all servos at 125% - they all work fine at that setting. No binding or warping seen so far during test throws. These HD-1810MGs from HobbyKing are very nice - plenty of torque to run this model's control surfaces!

Linkages are made with Sullivan clevices, and 2-56 threaded rods. Very secure, easy to adjust, and solid. The HD-1810MG servos have plenty of torque for this plane.

Pix below. Almost done!
Posted by SkyCadet | Dec 04, 2012 @ 02:46 PM | 3,626 Views
Just finished on Sunday my gear fitting onto the fuselage, and the ESC wiring. I'll be doing a static run on the power system before putting it into the plane, and a servo test before mounting the control horns on the plane. Then, it's pretty much ready to fly!

Too bad it's way to cold to maiden yet. This puppy may have to wait until new years.

The stock gear is too narrow and short to look scale, IMO, as said before - this turned out perfectly!

see pix below. The Yak 55 is really coming together now! I can't wait to finish her...

SkyCadet
Posted by SkyCadet | Dec 02, 2012 @ 05:58 PM | 3,528 Views
I just finished mounting the motor inside the mount. VERY close tolerance, and not much room for error. The motor shaft is sqaure and centered.

I test fit a plate on the collet (not my spinner plate I'll be using, but a spare one to evaluate clearance and fit. Below are a couple of pictures showing the cowling, shaft, plate, prop, and vanes - PERFECT fit.

Also, I will have to shave ~1mm off my new CF mains struts to fit into the slot on the plane, otherwise, VERY nice fit. Pix of comparision sizes below, too.

SkyCadet
Posted by SkyCadet | Dec 02, 2012 @ 04:22 AM | 3,472 Views
I recently picked up a version of RealFlight6.5...

I found a Yak55 electric that I moded and set color scheme to match the plane I am building. I estimated what the plane will do when flying, and even if my Yak does 80% of what this one can do, I'll be pretty pleased!

And sure enough, Friday, the motor and CF gear came in!!!

I have to trim some material off the inner mount plate to fit the 1250Kv RCTimer motor. But, it looks like it will fit! The CF gear struts are awesome! They'll fit just perfectly!

Below is a ~2 minute RF6.5 video of me trying my hand at some crazy aerobatics with the Yak55! Shot with my iPhone off the screen...

This particular airframe is 40% larger than the ZH Yak. FYI...

Enjoy, and stay tuned!

SkyCadet...

IMG 0339 (0 min 0 sec)

Posted by SkyCadet | Nov 29, 2012 @ 01:39 AM | 3,666 Views
I finished installing the servos, into both the wings and tail. Ran a 12" extension on the servos in the tail, and will be using HK servo wire clips on the wings so that a Y harness can affix the wing servo connections.

Also paint-tinted the outer fuselage front and epoxied the RX tray onto the rear runner behind the battery tray.

I used CF rod/1" balsa blocks on the mains for reinforcement, pictures shown below... Now, just motor, setting the horn throws, and then connecting the electronics!

SkyCadet
Posted by SkyCadet | Nov 28, 2012 @ 10:48 AM | 3,749 Views
I finished up the enhancement for the gear in the fuselage (mains) and some slots in the fuselage to permit the wing servo wires to be attached.

I used 1/32" ply and used CA to affix between the runners just aft of the main wing mount. I then cut a 1/2" slot, just wide enough to permit the servo connectors to pass through. The ply will provide a guard against wire pulling out during assembly, and also some protection on the siding (which is Monokote). I also used a small bit of clear monokote over the slot to strengthen it from ripping or running, just in case

Oddly enough, no slots or anything was on the model! Not even in the manual! Must be a quirk...

My gear mains are reinforced using two 1/8" CF rods running between the two main runners holding the gear mount, affixed with epoxy. I also took care NOT to have epoxy make its way into the blind nuts, so that when my CF mains arrive, these can be put on in lieu of the stock kit gear. Two 1" x 3/4" balsa blocks were also placed between the small runner struts above the CF rods, epoxied as well. This will be much stronger than stock, and the balsa is mounted with the grain running vertical for strength.

I'll shoot some pix tonight, as I am wanting to also paint the inner firewall, and RX tray. I was sort of tired last night, and did not do too much on the plane other than those two little things.

Stay tuned! Motor, spinner, and CF gear due to arrive any day!

SkyCadet
Posted by SkyCadet | Nov 27, 2012 @ 02:23 AM | 3,680 Views
Just finished the wing hinges and aileron mounting...

This model is a bit bigger than I thought it was going to be, but that's just fine by me! It is a nearly-ideal size as a general park flier and field plane without being overly cumbersome. I like it!!!

However, I realized when putting the wings on, the manual does not have accomodations for the servo wires for the wings to go through the fuselage!

No big deal: just some 1/32" ply inner wall with slots, cut the covering to make a small slot for the servo wires, and we're golden! Also need ot mount my RX tray (kit also did not have one per se, but an easy fix as per my previous blog comments 2 posts ago).

I also want to reinforce th emains inner walls a bit with some balsa to give th eplane a bit more strength there anyway, so I will be doing this while still awaiting the motor, spinner and mains CF replacement...

Pix below... looking to be not too much more to do, other than the servos mounting and control horns.

SkyCadet
Posted by SkyCadet | Nov 25, 2012 @ 03:00 PM | 3,553 Views
Well, I decided whilst waiting for the motor and spinner to arrive, that I'd finish up the canopy detail and cowling stuff...

The cowling vanes were made with 1/8" x 1/4" aluminum streamline, and I used 16 of them radially positioned off a 2" dia. circular plate I made from 1/32" hardply. It was made 3/8 wide about the annulus, to accomodate the spinner's collet and allow positioning.

CF rod (5/64") was used for the mounting posts, using graphite epoxy on the backside of the plate. A template was used to get the angles and positions very close to ideal. After setting, I had a small photofilter 46mm set ring (the ring that holds filters in their cells) and placed this on the rear to sandwich the CF rod and provide a bit more strength. The vanes are 24mm long, and sit through the CF rods so they all position correctly, and that thin CA can be used to hold them.

After setting the CF rods, I hit the annulur plate with flat black spray paint, then mounted the vanes. The vanes are mounted such that they recede from the front cowl, just as a wing profile would. The vanes were a bit too dramatic on the plane so I darkened them after setting lightly spraying flat black in a "fog coat".

They look more like a CF vane or dark grey tint, which goes nicely with the color scheme of the cowl I think (see pics).

Once the motor arrives, I can then mount these on the front of the motor mount using graphite-epoxy. There is about 2mm or so clearance inside the cowl so the vanes JUST fit inside the ID of the cowl. It looks pretty sharp, and adds a real scale look to the plane with minimal effort and time (~1.5h total for cutting and gluing, and 15 min of painting), without overly compromising the airflow through the cowl.

I am finishing up my ailerons later tonight, and then mounting the servos and control rods. Once done that, It's just a few more minor things, and the gear mains CF struts to receive, and I'm flight ready!!! (2h maybe?)

SkyCadet
Posted by SkyCadet | Nov 20, 2012 @ 01:14 AM | 3,517 Views
My horizontal stabilizer is mounted on the fuselage (still drying, so pic later).

Elevator connecting wire is in as well. Test fitted system before mounting - excellent fit. The 2mm wire was redone as the stock one was a bit bent. I used white glue in lieu of CA or epoxy. My tail slides into the fuselage, and I had to ensure that it could be fitted and aligned properly. CA is pretty fast, and may not fill in enough to hold under more extreme landing or flight conditions. I did the same with my Pitts 12 15e, and it works fine.

During the fitting and clamping, the stabilizer main section was a bit off from alignement, slightly angled. I clamped the tail after applying a bit of opposite pressure to re-align the stab. Double-checked everything before final clamping. It's aligned with the wings (test fit and cheked for alignment with stab).

The canopy is a plain bubble type, so I added some black 3M vinyl cut 4mm wide to simulate the actual Yak 55 canopy. Pic shown below. The vinyl applied well, but the compound curve of the front of the canopy bubble is hard to get just so. But we got it pretty close!

Sdiebar: I was concerned about the kit gear struts. They are too narrow and not very high. I ordered a CF gear from HobbyKing, which should be PERFECT for this plane. HK280-148 is the stock number. Once it comes in, I'll fit it in lieu of the stock gear. Most Yak-55s I've seen online (scale planes) have a wider gear strut system than the kit has. This will look more proportional - should be awesome.


SkyCadet
Posted by SkyCadet | Nov 17, 2012 @ 01:38 AM | 3,335 Views
Just finished touching up the chipped cowl and the wing servo mounts.

I color-matched the 1/16" ply inserts to match the wings. I MAY after mounting, decide to cover with clear monocote the wood to smooth out the look. I have to wait until my servo extensions arrive in a separate shipment before I finish mounting the servos. Should be any day now...

The yellow is cadmium yellow - a perfect match to the yellow on the wings. The black is semi-gloss black.

Pix below...

SkyCadet
Posted by SkyCadet | Nov 16, 2012 @ 12:36 PM | 3,277 Views
I finally received my Yak55 kit.

NICE! Build quality is rather good for a kit in this price range ($62.99 @ HK). All parts are accounted for, only a minor nick in the front of the cowling, which is easily repairable with some graphite epoxy and some black touchup paint.

The digital servos I ordered are smaller than the slots for the wing and tail servos, so I'll have to improvise with some thin ply to mount them. Pix below.

Specs for the servos:

Model: HD-1810MG
Voltage: 4.5v~6v
Speed: .13sec
Torque: 3.9kg/cm
Bearings: 1BB
Gears: Metal
Weight: 15.8g
Size: 22.8x12x29.4mm

These have a LOT of torque, and have been hailed as some of the better digital servos in the micro/mini size ranges (10g to 20g). They run $12.50/ea. at HobbyKing. I am looking forward to trying these - they have ~50% higher torque rating than my 82MG Hitecs I put in my Pitts 12 15e earlier this year. Stay tuned!

I am looking forward to building this kit! It is very nicely covered, and everything fits well. The canopy is integrated into the battery cover - an excellent design for battery/electronics access.

More to come!

SkyCadet