Cornell Rewinged

The other day was crazy windy. We flew only a couple flights, and they were a lot of work against a heavy cross wind with 10 mph winds and 20 mph gusts Stupid fun flying. So it was a great time to take my Eflite PT-10 Cornell up! Kenny Chandler, the only other flying fool, asked me why I hated the Cornell... then as I headed out to the flightline crabbed his camera and said he just had to film this!  (Here's your sign... but I was being bold!). Touchy cross wind takeoff in a plane that begs to roll the upwind wing, flying 45 degrees to the wind to run down the center line, kiting around turns near the tree line. There's always a nice burble on windy days along the tree line at the south end, and I flew into it. She rolled the wing nearest the tree line down hard, I compensated, she did it again, I over compensated... a nice pilot induced oscillation, tip stall, POWER, stall, crashes onto her wing. But it was a WILD ride!

Yesterday I redid the wing, and today the cote. Getting the cote right was tough as I learned how to use the heat gun (LOVE the heat gun for cote, but there is a very very thin line between shrink and melt...). I decided to redo the cote on the vertical stab... that was a pain in the ass and I redid it 3-4 times. The left side still isn't right, and I was too tired to take any pics... the wing came out pretty good though!

Pre-repair with the cote removed, underside right wing. The wing is broken clean through aft, a couple ribs and the leading edge spar, held together here by the top cote. I carefully peeled the S of U.S. off and would replace it later. 

Repaired the ribs and spars. The wheel box was shattered, though you can't tell from the pre pic. I had to remove the sheet balsa, reconstruct the box with the existing parts, build a new roof under it and then re-sheet the balsa. In rebuilding the cracked spars I used the technique below to add supporting wood behind existing structure.

I use popsicle stick wood, Dremel sand some arcs to reduce weight.

The wheel box is re-sheeted.

And the underside cote is done nice, clean and snug, using my newly developing heat gun skills. I did the underside easily, but the topside took a couple tries. I also put the S back on and made new periods.

But it too came out near perfect.

The dihedral is spot on, no new twists that I can see. The new wheel box is sturdy.

She looks great, though I wish the left side of the vert stab cote looked better... next time.

No pics, but I decided to change the motor. I had a HURC 2836-09 driving a 10x8 Master Airscrew powered by 3S 3300. I think this was a marginal power setup. I decided to change to a HURC Power Up 450 motor Kenny Chandler had given me. for a few more kv and 50 more watts of power without any more weight up front (remember she has the metal motor mount, so front end weight is an issue). I think she will fly a tad better, and can even handle a 4S if I want to. Hoping to fly her tomorrow!

UPDATE (1/1/12): Went back this morning and redid the left side of the vert stab, and it came out wonderfully. I also took a moment to strengthen the structure of the frame, which you can see through the cote in the pic of the right side.

Bad ESC update

Turns out Ray was right. He responded earlier to my my badESC post noting maybe the ESC throttle limits hadn't been set. He was right! I installed the replacement ESC and it did the same thing, alarming and not functioning. So I set the ESC throttle limits. After binding the receiver turn everything off and remove the bind plug.Turn on the transmitter, then move the throttle to high/full. Now power up the reciever. After the first start tones finish, within two seconds of turning on the receiver, pull the throttle back all the way. Let the ESC startup finish. It should no longer alarm, and the ESC should function properly. It works fine now! Thanks, Ray!

I NEED MORE POWER, SCOTTY!

The good news is that my Hangar 9 Sopwtihfits in my new car. I traded in my Lexus IS 350 for a more economical, and while smaller, roomier Lexus CT200h. Now I don't need to borrow  my wife's crossover anytime I want to fly more than one plane, and driving to the field doesn't cost me $10 in gas. I actually like this car better than my IS, and I loved my IS.

Its a tight fit, but it works! I was able to get my Eflite Pulse XT25e, my Electrifly Cosmic Wind, my two PDYSysytems carriers, my battery charger box, and my radio box all in there. Very nice!

The bad news is she still flies like a pig... She took off from the middle of the field and this time rolled left despite full right aileron and then right rudder, and back into the ground. She bent her motor mount, broke her prop, cracked the cowl, knocked a piece of the mock motor out, and broke her wing. When the wing twisted, the wires snapped, again. Looks like I lost a turnbuckle to boot. Vinsen was there and he echoed my concerns since the first flight, that the motor is not powerful enough. She has a 14x8 prop, lifts off, but doesn't seem capable of controlled flight, just waffles. I ordered a true 60 size motor from Heads Up RC. The plane is stock recommended for an Elite 46, which my installed HURC 4260-06 motor is a replacement for. Many builders have done fine with the Elite 46, but most are recommending steppjng up. Since her power has been bothering me, I opted to buy aHURC 5065-04 motor, which is equivalent to a true 60 size motor. I also purchased a Hobbywing C-Platinum 100A ESC, to upgrade from the installed 70A ESC. I wonder if I should step up from the 14x8 prop? This motor has a lower KV, but I am also going to ramp up to 6S from the 4S I had tried. My fear is she will just crash harder...

Thunder Tiger eHawk 1500

Yesterday was a marginal day flying at BMF. Very windy, which limited our flying. I did take the Hobby King ASK2100 up. We know how she flew last time we tried that.

I flew her a couple of times... but she hated the winds. Her wings flexed  and bent in flight, her tail twisted, and she was a bucking bronco between being carried by gusts to following her own lead when her control surfaces twisted in flight. It wasn't any fun, and every flight ended in a tip stall. I gave the controls to Paul Minnick. Immediately after launching her she kited up and backwards, then flipped nose down as she shot over the pits. He cut power to avoid the pits, clearly having no control over her, and she simply drove herself into the ground. He felt awful, I felt it was inevitable. She was a terrible aircraft. So I removed the receiver and gave all her parts to Greg Reed, who loves a challenge.

I still love my Diamond 2500, but I am done with foamy gliders. I need a new glider, less than 2 meters, power, and not foam, for a low price. I like T-tails, but that means fiberglass (or heavy foam like the Diamond), but I also like V-tails. I found this Thunder Tiger eHawk 1500 at Tower Hobbies for a very reasonable price. I couldn't find any legitimate gripes about her. I watched several vids and liked the way she flies. I will build her stock but want to work on giving her separate aileron servos (don't know why they didn't do that) when I can figure out how to make the cuts in a new servo tray. She needs spoilerons or will be challenging to land at slow speeds. She should get here by the end of the month. Looking forward to her and learning how to program V-tails!

Waffly Warthog

Took the A-10 Warthog up yesterday. She really didn't have enough thrust to takeoff from grass without a good head wind. She rolled fine on her big wheels, but she just didn't have the thrust. I did manage to takeoff once into a gust, but otherwise I hand launched her.

The pic in the manual that sets the CG at 80mm from the tip of the pylon is incorrect, as one might imagine. I set it about a third back from the leading edge, which put it over the spar, and it was spot on. I had set my low rates for elevator at 50% with 25% expo. She porpoised a lot, so I ended up setting it at 35% and it settled down. Elevator authority is no problem! She is marginally powered with the two 64mm fans on a 3S. She has 40amp ESCs, so she could handle a 4S, but I would have to chisel EPO, and I don't know if the extra weight would bog her down more than the 4S would improve her power. She hand launched easily, but her size and power require she be launched by a flying buddy. Once she waffles up to speed and is truly airborne she flies fine. She is no speed demon, but she is quick. She trimmed out easy, and once I got her elevator expo set she flew quite stably. On landing with power off she loves to float, and her gentle stall behaviors let her come down nicely.

I did have problems with the retracts. They bind, and it took some surgeries on the case to resolve that. The cheap stock servos on the mains burned out, one yesterday, and another today. I replaced them with Tower Pro SG-90mgs. Yesterday's went in no problem, but today's was "reversed" so the left main was out of sync with the nose and right main. The servo was moving correctly, but the installation would not let me put it in "backwards" to get it in sync. I don't know why this servo was different than the stock one, but it is, even though its installed the same. I ended up getting a servo reverser, and its all set now. I didn't get to fly her today due to this retract issue...

Tomorrow I hope to take her out and see if I can takeoff from the ground. Hopefully the grass will be cut before then so I can get her rolling!

BlitzRCWorks A-10 Warthog

Its not like I needed a new plane, but I go this one during the Black Sunday Sale at Bananahobby for less than half the price, in fact, almost a third. Its the BlitzRCWorks A-10 Warthog. I had wanted the camo one, but it was NIS, so I got the Black Lightening one. She is very nice! In set up one of the landing gear retract servos burned out, but the rest of her is working just fine! I didn't blog the build, it was very simple: bolt on the wings, stab, etc. The multiple wires took a bit of time, but that was easy too. Some areas of paint came up with low tack tape so had to be repainted. I set her up with flaperons, and slowed the retracts down to 3 seconds.  Her wheels are large enough she should have no trouble with the grass runway at BMF! Looking forward to flying her soon!

Salvage...

Went through the remains of the Diamond 2500 Power Glider... the rest goes in the trash.

Silver on Red

Kenny Chandler suggested a silver prop spinner would look smokin' on the nose of my very red Cosmic Wind, so I ordered one from Maxx Products International (MPI).  What do you think?

Before: Red Spinner

After: Silver Spinner

Physics is consistent, I'll give it that...

Well, yesterday I flew the ASK 2100 power glider, and landed her with the spoilerons with good speed, and she landed sweet with remarkable sink. I am also aware that she will tip stall like crazy. And I know that if you want to tip stall more spectacularly use spoilerons at stall speed. So what did I think would happen if I made my approach at just above stall speed and tripped the spoilerons, especially after I saw her do it twice at altitude while slow flying today. She tip stalled and dropped like a rock right on her nose...

Despite a fairly high speed spinning crash she came away pretty well. The nose is cracked on both sides as can be seen here, with a little foam squish. The motor and motor mount are fine. The long canopy snapped on the foam part. Epoxied everything back together easily. Good as new!

I tried a carbon fiber spar in place of the aluminum spar, which of course had no dihedral. The aircraft flew much better for being lighter and didn't seem affected by the loss of the dihedral. But on flaring for a landing the spar snapped and she dropped to the ground in a semi controlled landing. I put the aluminum spar back on and curiously, she still flew well! Today she flew more stably than she did yesterday. Conditions were much, much calmer. Flew her several times and she was a pleasure! And then I tried to defy physics...

Tomorrow is supposed to be an even better day! I am nervous because I plan to maiden the Hangar 9 Sopwith!