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Archive for April, 2012
Posted by SkyCadet | Apr 21, 2012 @ 11:16 PM | 3,783 Views
Just got in from a great first flight!

This is a tad nose-heavy, so I'll need to readjust my battery next flight. Evening was almost dead calm. Plane's axial and lateral trim was bang on, just 2-3 notches on the up trim for level flying at 50%.

I was surprised how FAST this plane flies, even at 45-50% throttle!

5-1/2 minute flight, with 1st 1.5 minutes closer to 65-70% throttle as I adjusted trim for 50% level out. Came in a bit hot on landing, but flared smooth onto the grassy field. No bounces or nose-ins!

I am going to have a hoot with this plane!

***Update: Just finished charging the pack. 1150mAh consumed of the available 2100 (75% level of the 2800mAh in this pack). Since I estimate a 7-7.5 minutes of general cruise based upon my static measurements with this system, the 5.5 is closer to 7 or so at 45-50% throttle. So, I should get around 12.5 min. if cruising, 9-10 with mixed flying, and probably 7-8 min with more aggressive aerobatic flying...

Smooth skies all! Enjoy the maiden video - thanks to Rob R. for shooting as best he could with the video - the plane went very fast - and hard to follow...

SkyCadet

Pitts12_15e_Maiden.flv (5 min 37 sec)

Posted by SkyCadet | Apr 21, 2012 @ 01:19 PM | 3,501 Views
Just finished a preflight final check before maiden.

Currently windy, so I'll have to wait until the wind dies (30km/h gusting to 50 right now!)

SkyCadet

Pitts12_15e1S.flv (1 min 55 sec)

Posted by SkyCadet | Apr 21, 2012 @ 12:12 AM | 3,735 Views


I now have the plane ready to fly! The weather calls for good conditions this weekend, though I may have to wait until Saturday late pm to maiden. Will post Youtube flight when complete!

I extended the battery tray, and now can run both my 4S 2800s and 3S 5200s within the CG limits of the plane. Sweet! I'll start wiht the 4S to get a feel and then try a 3S later on. The CG seems bang on 4" aft of the leading edge for fuselage level. I'm very happy with that.

Meantime, I used light graphite epoxy to attach the canopy. I had a bit of a time getting this to seat just right. It went on decently, but I have a slight offset on the left side (only 1/2mm or so, but noticable near the canopy rear). I also had difficulty sealing the leading front edge despite applying a good helping of GE on the canopy.

So, I sealed this with white glue. Not to hold, but to avoid airflow into the canopy, and reduce drag.

Below are the pixs of my finished baby! I put two 1/4" wide slots near the fuse underside rear for exit air. ALL Ready to go!

Stay tuned for a hopefully eventful maiden flight! Will try 7 minutes the first flight.

SkyCadet
Posted by SkyCadet | Apr 17, 2012 @ 01:25 AM | 3,574 Views
After a horrible weekend of weather, toady after work was just nearly perfect! I wanted to finish working in the new 2S Lipos for the decathlon, so I flew it 4x to work in all the batteries. Flew great!

I then brought out my Lancair ES. It flew superbly in the calm, 55F/11C weather today. The wind started to just come up as I was landing. Another great day of 6 flights total! When you get days like this, you KNOW why this hobby is so much fun!

I hope everyone got to fly in the past few days... Just waiting for those darned 4S Lipos to arrive to be able to maiden my Pitts!

SkyCadet
Posted by SkyCadet | Apr 14, 2012 @ 12:23 PM | 3,509 Views
It is rainy and sleet/snowy today, and expected for the majority of this weekend, so no flying!

I decided to verify my MAS 12x6x3's balance - it was slightly out after tip painting a few weeks ago, so I re-balanced it. I ran a 100A, 4S test battery with my Watts Up meter in line for a full static test run.

WOT/full throttle yields 494W @ 39.4A. This plane REALLY pulls hard at anything above 55% throttle. Should fly great! Static cruise tests at 45% and 50% yielded ~146W @ 9.8A and 205W @ 13.8A respectively. Using these numbers, a 2800mAh 4S battery should run (to 75% cutoff) around 11 minutes at cruise, and 8-9min on more agressive flying.

Since static tests are usually higher by 10-15% in my experience on average, that's 10-12 minutes of flying per 4S battery. Pretty good - maybe 7 or so with superlative aerobatics.

Just awaiting the batteries to arrive, and then we should be good to go!! I can hardly wait!

SkyCadet
Posted by SkyCadet | Apr 12, 2012 @ 04:42 PM | 3,521 Views
I recently procured some 1200mAh 2S Lipos from FMT Model on eBay.

The specs are:

Specification:

Output: 7.4V(2S1P)1200mAh, 20C nominal, 25C burst for 15-20s
Weight About: 58.7g
Dimensions: 55(L)*28(W)*19(H) MM

Pic below from their site. Mine came in at 56g, which runs my Super Dec BL now for over 16-17 minutes per flight on a MAS 8x6 3-blade and 1400Kv RC Timer motor (see earlier blog entries for details on that retrofit).

The new system with new batteries tops over 100W on WOT. (103W). This is easily enough to do pretty much unlimited aerobatics with this plane now, nearly double the power of the stock model power system.

I can squeeze about 20 minutes max. flight times with gentle cruise (45% throttle).

While the stock 2-blade can do this on a 800mAh battery, or nearly so, the thrust and general aircraft performance is nowhere near what I see with the 1400Kv/1200Mah 2S/20A ESC system!!! It is like night and day...

THis same system, or one similar, may be of benefit for those wishing to squeeze more out of their 15-20oz. plane. My SuperDec BL is almost 18oz. full up weight...

SkyCadet
Posted by SkyCadet | Apr 10, 2012 @ 11:10 PM | 3,765 Views
I decided that I wanted more robust axles like on my Lancair, so I got some Dubro #246 1/8" x 1.25" steel axle shafts. I put these on my Lancair ES, as I said above, and they are solid!

I did not wish to compromise my new Pitts by having a wheel fall off on landing...

This new system also includes (what I added) 2.5" Pro-lite Hangar 9 wheels (larger than my 2.25" ones and more scale looking), 5/32" brass shims (made from tubing I had spare), and the stock collets and washers that came with the kit.

Much more sturdy, and should fly better! Just optimizing the plane before flying!

Pics below...

SkyCadet
Posted by SkyCadet | Apr 10, 2012 @ 01:16 AM | 3,570 Views
Came in tonight from a great session with my Lancair ES by Great Planes. I built her nearly two years ago, and flew her only 3x in the fall of 2010. I flew it about 8x last year, and put in a new power system (motor is now a 1120Kv, 335W RC Timer motor).

With a Eflite 30A ESC, the 1120Kv motor and 9x7x3 MAS prop on there, this really zings along! I also upgraded the aileron linkages to Sullivan Clevices and 2-56 threaded rods. MUCH better aileron response, and better overall roll management. She trimmed out in no time, and I did a few fast passes, some general cruising at 45%-55% throttle. I use 2100 mAh 40C Lipos and this consumed about 760mAh of the available ~1600 (75-80% cutoff point) so even with 2-2.5 minutes at near WOT during the several passes, I only used about 50% in the ~9 minute flight. I get just under 22 min max on sedate flying with this system - pretty efficient considering WOT is 295W/9000 RPM for a max flying speed around 60 knots or 115km/h or so!

Pix below... I really like this little rocket! At 33oz. this runs ~140W/lb.!! Pretty sporty.

SkyCadet
Posted by SkyCadet | Apr 09, 2012 @ 08:21 PM | 3,152 Views
I decided to put on bigger wheels on the Pitts to handle deeper grass. I opted for Hangar 9's 2.5" Prolites. I used a 5/32 Brass shim to mate to the axles, but I am planning on getting a better axle system to handle beefier touchdowns. The stock setup seems like it might come loose over time.

The 2.5" wheels look better, and should handle things a bit better too. I had 2.25" H9PLs before, these have more of a "tire" look to them - closer to scale photos I've seen with PItts 12s on the net that do not use pants.

I also medium-tinted my canopy, it looks darker due to the lighting. It's at about 55% tint. I finished cutting it and smoothing it out, just need to glue it on (waiting until I can decide how the balance is planned, as I may add some weight in the cockpit rear).

Other than that, just waiting for my 4S batteries to show up, glue the canopy, and I'm flying!!!

Pix below...

SkyCadet
Posted by SkyCadet | Apr 06, 2012 @ 03:40 PM | 3,233 Views
Well, I powered up my plane after attaching the linkages to the ailerons. At 4S, 1/2 throttle (inside, that is as far as I wanted to try!!!), I got 209.4Wp at 14.09Ap.

Not too bad. This should pull around 400-500W on full up WOT.

At cruise (50% or so) I should get about 10 minutes of flying time...

Pictures of the finished plane (sans canopy) below. Empty weight is 1425g (60oz.).

Just have to balance and weigh the unit. At 50% throttle, this pulls a LOT with the MAS 12x6 3-blade prop...

SkyCadet
Posted by SkyCadet | Apr 05, 2012 @ 11:00 PM | 3,480 Views
I used a Sullivan Wing wire kit and an extra spool of 30' wire (needed about 3 feet more than I had in the kit - figures...).

My approach was different than many - I wanted a clean look to the wires, without all the turn buckles and such. So, I used the grommet mounts on the wing struts, and two eyelets on the cabane rear struts, and two on the gear struts.

This way, I use one set of wires on each side and level to snug up! Two bottom strut wires go to the upper rear cabane strut through an eyelet, and the other side same. The top strut wires on both sides go to/through the eyelets on their respective sides at the gear. This allows a shared load between wires, and a cleaner setup (but trickier to install!). The loops are affixed with crimps and CA, any excess is removed via a Dremmel and diamond wheel (carefully!).

See pictures of this below. I adjusted the tension using the nuts on the eyelets to be able to increase tension on two wires at once. They are taught, but not too tight, and I have enough room to adjust them further if need be...

Now, the aileron linkages, and prop/canopy and balance! Whew!

Skycadet
Posted by SkyCadet | Apr 04, 2012 @ 02:18 AM | 3,073 Views
I decided to make my plane look more stock than it was, so I added exhaust pipes off the airscoop just like real Pitts planes. I know, not really needed, but it just adds that something "extra".

I also am going to paint my cabane struts like the stock plane too. I removed th etop wing and struts, and graphite-epoxied the underside scoop to the fuselage. Mine was horribly fitting, and there's NO way that CA would have held it in two teeny places at 30mph+. I used my Dremmel tool with a carbide 1/8" cutting tool to match the curvature of the underside of the fuse as best I could, then used graphite-epoxy 1:1:1 to adhere it. This also flows nicely out and is BLACK. It filled in the gaps very well, and the scoop is rock-solid.

I then made two pipes out of 3/4" pieces of aluminum: 7/32" dia. and 3/16" dia.

They fit inside each other, to make a virtual exhaust pipe. A little CA, and some flat black paint dusted on lightly, and they look like they've been busy!

I then carefully added a small slab of balsa on the front behind the firewall on the inside of the fuselage's wooden spars to allow me to drill into the fuselage at an angle - this worked very well. I then use graphite-epoxy to adhere the pipes into the holes drilled carefully at an oblique angle on either side of the scoop, just like the real McCoy. The GE fills in nicely, and flows out to smooth out and cover over any left over roughness in the holes. A touch of GE inside the...Continue Reading
Posted by SkyCadet | Apr 03, 2012 @ 01:04 AM | 2,922 Views
Well, I am almost ready to go.

The top wing is attached - I opted to use 2.5mm cap screws, 2x 2.5mm washers, 10mm length to the screws. They seem to be better in the slots and more rugged. The wing went on pretty much like clockwork, except that I need 8 more washers to complete the cabane strut total.

I think my wires will be dual ones: two bottoms to the rear cabane, two tops to the mount I have in the gear strut. I have seen this on a couple of planes, and it looks great.

The only other thing to do is to tint and eventually mount the canopy, and cut some rear underside slots in the fuselage for exit air, and finish the aileron linkage with the ball sockets and rods.

I have 2800mAh 4S Lipos on the way for this plane. Should be a nearly perfect fit and balance. I'll pretest the balance with a "dummy" load (simulated battery using 2xD alkaline cells that weigh close to the batteries I'm getting (288g). I'll then determine if I need a small weight in the canopy section to re-load the plane or not.

I'll probably have the plane fully done this Wednesday, if nothing else goes awry. I may need a second wire kit but we'll see how much I have to work with.

By the way, the 900kV RC Timer motor had a misalignment in the rear bearings, which held the rotor slightly too far forward by a hair of a mm. A good friend and I adjusted the bearing seating in the main shaft, and re-lubed the motor. It now runs MUCH smoother and quieter. As a precaution, I have a replacement on order, but will fly this unit during maiden trials to determine its performance.

SkyCadet... gettin' closer!!!!