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Old Jun 18, 2015, 01:34 AM
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Gotta Get in the Air!
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United States, WA, Kirkland
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Build Log
MM Glidertech Marauder rebuild with electric

So I'm (re)building the Marauder after an unfortunate bit of clumsiness a few years back when I crunched a spoiler bay during a move.
My local field has a lot of different users and a high start or winch is not a safe bet. I spoke with Merrill and he told me to "chop the nose off and put a motor on that sucker."
I've got a Turnigy Gliderdrive 840 kv, a 60A speed controller and a completely stripped, repaired and resanded bird.
I'll begin the recovering tomorrow.
I've never flown electric gliders before so all of this is new to me. Thanks to Mr. B, hogtosoar and AEAJR and countless other people who've gone before me, this newer Marauder should rocket into the skies. I'll take pics and add them here for perusal and discussion.
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Old Jun 19, 2015, 08:56 AM
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.: Looking for Thermals :.
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Quote:
Originally Posted by Hawk_Eagle View Post
...I've got a Turnigy Gliderdrive 840 kv, a 60A speed controller...
What prop size are planning to use? And what battery voltage?
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Old Jun 21, 2015, 12:37 AM
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Status and update: Marauder

I'm going to bench test my motor first with a 11X7 and a 12X6. I bought a 2200maH 3S 35C battery for the test. I'd like to get a 4S 40C 2200maH battery for normal use.

So after three days of deciding what I wanted the Marauder to look like, I decided on Transparent yellow on top, with yellow trim, violet transparent on bottom with red trim. I'll stylize the empennage similarly.
The fuse will be yellow with red on the bottom.
I've got some connector soldering to do and to build a test stand. Borrowed a watt meter. I'm not sure yet what readings indicate which prop will serve the glider better.
I'm probably not going to test the static thrust.
I also need to complete my power supply for the charger and purchase a folding spinner and props after I determine which prop works best. I anticipate having more than enough power to do what I want it to do.
I would have kept going but apparently a covering iron needs to cool down .
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Old Jun 28, 2015, 12:14 PM
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Gotta Get in the Air!
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Motor test with fixed props

So after a lot of researching, thinking, debating, learning, I built a motor test stand. I built it to measure static thrust as well. However, I've learned my scale is limited to a kilogram or 33 ounces.
I've purchased folding props and a spinner, sized 11X6.5 and 12X6.5 and will test those as well after I get them hopefully in the beginning of the week.

So far, this is the data I've accrued this morning:
Gliderdrive 840 KV

Prop 11X7E
3S/2200maH/35C -25A / 280W
4S/2200maH/35C - 34A / 494W

The motor was minimally warm after max load was placed on it.

Prop 12X6E
3S/2200maH/35C -27.4A / 311W
4S/2200maH/35C - 37.4A / 524W

The motor had increased temps with the 12 inch, but not so hot I couldn't touch it.
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Old Jul 02, 2015, 12:37 AM
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Nose II

Cut a motor mount with cooling holes on top, though I probably won't need them too much as I'm not planning on blazing across the sky with the Marauder.
Next I removed some of the forward bottom sheeting, and contoured the fuse sides more in line with the 40 mm spinner.
I added sticks of 3/8 triangle stock and glued in the motor mount at 3 degrees right angle; no down angle. I've read multiple differences of opinion on this and split it down the middle, metaphorically.
After the glue dried, I cut a T-shaped piece of 2oz fiberglass cloth, lightly coated with spray adhesive, centered it on the motor mount and wrapped the rest around the bottom and sides. I painted Polycrylic into the fiberglass.
Tomorrow, will probably fill the fiberglass with light spackle and then sand.
I've been recommended to put some reinforcement on the inside as well. I may do the same thing on the inside as well.
I'm looking forward to receiving the folding props and testing those. Then onto finishing the covering.
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Old Jul 04, 2015, 11:06 AM
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Covering and folding props

Finished covering the tailfeather and spoilers. I discovered a crack in the rudder, so I repaired that as well.
I sanded rough edges on the folding props so they would fold out without impinging on the spinner, then built a prop balancer with rare earth magnets, bought some topcoat nail polish and balanced my prop blades.
I conducted a motor test of the props and determined the 12X6.5 prop with the 3S battery is my best combination.
Now I'm determining how to place all the electronics inside the fuse. And then cover the fuse. I'm almost done. It's been nearly a month since this process began.
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Old Jul 08, 2015, 10:06 AM
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Functioning rudder and elevator

After battling with control rod geometry for too long and trying to negotiate around the battery, I decided to place two HS-81s just behind the battery bay under the wing, with servo lead extensions.
Tested the swings and I've got full deflection.
I lightened the tail somewhat by using 1/16th inch balsa for the top aft sheeting. It looks better than when I did it the first time with 3/32.
Now I shape the canopy to match the spinner, cover the fuselage, install the spoilers, check them for operation, balance on CG - should be good to fly - soon!
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Old Jul 09, 2015, 09:05 PM
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fuselage covering complete

Fuse covered. She looks good!
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Old Jul 10, 2015, 12:37 AM
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Watching your progress. Looks cool. Not long now ...
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Old Jul 10, 2015, 09:47 AM
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Thanks

It means a lot to me that someone is watching this.

Spencer
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Old Jul 10, 2015, 09:54 AM
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There are more lurkers out here than you think. The Marauder is a respected plane and electric power is popular these days. I bet your thread has many followers.

Tommy
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Old Jul 10, 2015, 10:05 AM
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Followers.... lurkers.... I'm sure that there are lots of us. Keep the details (and pics) coming!
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Old Jul 10, 2015, 02:07 PM
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Chile, Quinta Región de Valparaíso, Los Andes
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IMHO those HS-81 would be an overkill, I would go for lighter ones, like HS-55 or it's digital sibling, HS-5055
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Old Jul 10, 2015, 02:19 PM
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WAA-08 THANK FRANK!
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Las Cruces, New Mexico, United States
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You will want an outlet for your forced air cooling, otherwise you will see no benefit to ramming air into the fuse!

Air moves from high pressure to low pressure - make your outlets 1.5-2.5 times the size of the inlet size. I like the NACA ducts for air handling/directing - here is a sheet of them for 4.00

http://parkflyerplastics.com/cart/in...roducts_id=278

Your project is beautiful - fly well
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Old Jul 10, 2015, 03:23 PM
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air scoops

Where are you recommending I put the scoops?

I'm looking forward to seeing it all put together. I work on the spoilers after work, which shouldn't take too much time.

As for the HS-81's, they're already installed and they are what I had on hand. When I had only radio gear in the front, I had HS-311s installed. The spoiler servo is still an HS-311.

Spencer
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