Last Flights of the Pulse #3

After two great days of flying I felt I had my flying fingers back. Today something was off... I kept telling Aidan (my eldest son, new pilot) that I was screwing up my right/left orientation in odd flight orientations, and a couple of times I had to make quick saves. I flew the first battery otherwise fine, but on the final landing approach, I deployed the spoilers and underestimated the loss of airspeed and lift. Despite adding power she was mushy and landed short and hard, ripping off the landing gear, tossing the fixed canopy (its glued on, it doesn't come off), and poking holes in the wing and bottom of the fuse. I've done this before, easy fixes in the pits. The second flight was similar, making stupid orientation mistakes, then on landing I made the same mistake in a less forgiving place, the perfect storm.

The spoilers were certainly reducing lift, but they were also increasing drag and making control movements sluggish. I had mastered them last time I flew, but today was flying behind the aircraft. As my Marine pilots would say, "We're on takeoff roll and he's still in the parking lot getting out of the car...".  I came in over the trees on the south end, always gnarlier on approach, and she started to waffle. Power... she stalled rolling right, I tried to correct, but rolled her more right with dumb thumbs and she rolled quickly right into the last tree before the field and fell into the woods with a whack...

First run up before first take-off.

Out to the center... and off!

Landed short on the other side of the road...

Scene of the resting spot after the slide following the crash. It was actually pretty cool...

Surprisingly not destroyed. The wheel pant punched a hole in the wing as the landing gear were ripped off the plane, the wheel pants off the landing gear. 

On the bench, discovered a few other problems. Had to repair a wing rib under the hole the wheel pant drilled. Used super cement to put the landing gear back on (its probably why the wheels didn't fall off in the second crash, but the fuse ripped in half). Aidan put the wheel pants back on.  Used "field cote" (packing tape) to repair the holes. 

Everything back to normal! Electronics all good.

Field repairs look good.

And we are off for the second, final flight. Flew fine, whipped it around a bit. Wind shifted to require a southern approach over the woods. I didn't make it.

Aidan in the woods immediately off the south end (The Woods of Mordor). Nature all over him. The plane wasn't more than 10 feet in, but it was thick. He was a good egg going in for my plane, my being in shorts and flip-flops...

The carnage did not look so bad at first...

Aidan said, "This man did this...".

Yes... yes I did.

Aidan conducting the autopsy. He removed all the hardware, all of it was fine. Battery was not "crashed".

It became obvious that the cote was holding the forward fuse together. This is really not repairable.

Wing is twisted. I have always considered the wing the heart of the airplane, and breaking it up to put it in the trash was heartrending.

Her ignominious end, the bottom of a MCRCC trashcan, stripped of her hardware... sniff.

I have received funding authority to purchase a new Pulse 25XT airframe! Ordered and shipping tomorrow! This, I am embarrassed to admit, will be number 4, in 7 years.

Not being a fool, I decided not to maiden the Sbach. It not being Kenny's airplane, he cajoled me into flying it anyway... Next post!

Sbach Power Tested

A few weeks ago I did the eCalc projections for various setups. Today I power tested changing only the prop to a 17x8e APC which is what I will fly her with to start.

 

Here at full throttle we peaked at 1635 watts and were running at just a spit below 1400 watts on 6S. Motor was cool, battery warm (a 30-40C battery). She drew max 65 amps. The 3300 mAh battery drained in about 5 minutes. I have 4000 mAh batteries that I believe will fit, so I will need to time trial them at just above half throttle, but the 4 minutes sucks. It will be easy to series in two 3S batteries for 6600 mAh, so I will also give that a try. I put 8 S on there and by half throttle was pushing 2000 watts, so stopped that test. It was also heading right where eCalc said it would. The motor is rated for 1700 watts. This plane has pleeeennty of power 6S. Just needs some legs, so I suspect I will be using a lot of 3S in series. I may someday try a 16x10...

Checked the CG and its right at about the directed 106 mm from the leading edge a couple of centimeters from the wing root. If anything it's nose heavy, so it's good to go. I also set the expo at 25, 50 and 75. I have been flying most of my planes straight 25% (sorry Kenny, I misread it when I told you I was already flying 25, 50, 75).

With that she is officially ready to maiden!

UPDATE (4/25/14): Oops... Series vs parallel error explained here.

 

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Pulse Exercises

Finally got a few flights in today. I went out when it was not too windy, but as it does here the winds started to increase as the morning passed. I had driven the 26 miles to the field, I was going to fly dammit.

 

It wasn't too bad, actually. Calm with brisk breezes, 5-8 mph, shifting from the west but generally southerly allowing for decent approaches. The overcast was a bit much and I lost orientation a couple of times, so put on my ambers which improved things immensely. The new batteries produced clean steady power. I worked both spoiler end and non-spoilered landings, and had to throw in a few slips on occasion. Lots of fun and got my fingers back as well as my mental state: flying instinctively rather than thinking about stick moves. The video is long, series of touch and go's. Feel free to skim. I used the Looxcie, so the quality isn't great and for some reason the sound went in and out.

 

 

 

Enjoy!

 

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Skyline/Goldwing Sbach 70 Spinner Installed

The Sbach Du-Bro 2-1/4 in (60mm) plastic red spinner with aluminum back plate came in today, and I installed it. Rotored it the aluminum center hole to fit, and Dremeled down the larger prop openings (there are nice guidelines inside the spinner. Tried to make them smaller, but when it fir it was at the marks...). It installed wih a sweet gap and perfect no-wobble centering. I also put an APC 17x8e prop on it. Later I will power test it on 6S and 8S batteries.

 

 

 

 

The only thing I am waiting on to call it done are the right stickers!

I am thinking I will take the cowl off and out in a washer of right offset before first flight.

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Pulse 25XTe Gets a New ESC

Yesterday the new ESC came in for the Pulse. I was using a bargain 60A ESC with a linear BEC, which was fine, but now that I appreciate the finer things I upgraded to a HobbyWing FunFly 60A ESC with a SBEC. I removed some of the shrink wrap from the ESC to expose the cover to the motherboard to improve cooling. I wasn't sure if it was the fin side or the MB side, so just cut away the non-label side. Either way it works. I had decided to move the ESC to the top rack directly in the airflow, with good flow around the battery. It enters the batter compartment a bit, but now there is room for the battery to move aft, which is nice as I need a little more aft CG. The ESC is held in place with the omni-use Duo Lock Velcro I so love. I tried the old batteries, and they all just crapped out. They are old and heavily cycled, so they needed to be replaced, but damn, at $25-50 a pop it hurts to recycle 5 of them. I remove the leads to recycle the wires and connectors, and for safety, covering the dead ends with liberal electrical tape.

Another stormy day here on the Gulf Coast... No fly for me. Expecting the spinner for the Sbach any day now. Will install, check CG and set the throttle limits, which I forgot to to (remembered it while programming the Pulses ESC).

 

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Wind... Every frickin' day...

When it's beautifully clear outside its blustery. Can't catch a break, and looks like we won't for over a week to come.

Waiting for the replacement stickers, the spinner (both one I ordered not expecting General Hobby to send it since they didn't respond to my last email, and the one I ordered), for the Sbach, and the 4S batteries and new ESC for the Pulse. I really wanted to find an Ultimate spinner for the Sbach. The Tru-Turn one is $35 and looks to require a special adapter, which won't fit on my motor.

Kenny offered I should try to find nylon or plastic wing bolts to break away in a crash. It is impossible to find them! I don't understand that. I did find some in the UK but it costs twice as much to ship them as to buy them.

I have been thinking about the eCalc numbers versus what I found when I watt tested the system. My results came very close with 6S. I wonder that 8s would really increase the power flow that much?

Idling away, meanwhile...

 

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Sbach 60" versus Pulse 25XTe 52"

For comparison. The Sbach 60" wingspan next to the Pulse 25XT 52" wingspan. The Sbach flies 6S to 8S and the Pulse flies 4S. The Pulse is my best flying aircraft to date. Can't wait for the spinner to arrive so I can set the CG and call the Sbach build done.

 

Posted with Blogsy