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Sep 15, 2017, 05:27 PM
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Build Log


Rescue Plane.

25 Years Old. .....Multiple Owners.......Never Flown

So I converted it to Electric, stengthened its structure to Airworthy Levels.... while actually reducing its weight 3 3/4 Pounds.... and I've got a hit. Cost very, very little. For one....its no looker and not the greatest scale. Although I removed some machine guns and scale features for initial flight tests (it looks better than these pics). But its also beat up from years of Hanger Rash and had many other problems. Like one prior owner cutting away much of the main spar at its greatest stress point---to make room for 2 servos to operate the Bomb Bays. No Wonder nobody dared fly it.

Took maybe 2 months to resurrect. Far less than building one. I am posting this after-the fact partial Build Log so that others interested in an electric Ziroli can find some helpful information.

I sure wish I had this info when I started. I was able to find only 1 or 2 electric ones on the internet and no details
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Sep 15, 2017, 05:41 PM
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Electric Ziroli B-25

And the advantages of electric power are huge.

Most important---the Grim Reaper of Engine Out (which claims most of these planes) is much less likely to come around. .Contrary to widespread belief....the risk of engine out on electric multi engine planes is very serious.. due to many factors.... But its nothing compared to the risk with internal combustion engines.

This advantage alone outweighs everything else. Just ask the dedicated gas guys who have watched their B-25, P-38, etc spiral in within seconds after engine out .

Most of the other advantages are well known so I won't repeat. But they are actually stronger than you may realize. For example..many know that electric can make counter rotating props an easy reality freeing the pilot from nuisance torque, P-factor etc. But it also can provide additional insurance against Engine Out Loss----if the counter rotation is arranged towered the top or the fuse instead of the bottom. This invaluable fix takes 5 seconds on electric planes.
Sep 15, 2017, 06:01 PM
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Ziroli B-25--replacing gas engines with electric

Here are the engines I unbolted. In their place...Hacker A-60 5SV2s, plus JETI Spin 125 ESCs, plus four Gens Ace 4s 4800 60 C and Castle Heavy UBEC.

I framed up these engine mounting boxes from ply--held together with both glue and aluminum bolts. Despite the extra weight of these boxes....and despite the structural strengthening I had to add to the mutilated main spar, and , to lesser extent,....throughout the airplane.... despite all these additions the final weight is 3.75 pounds LESS than when I bought the ship. Thats partly due to a weight advantage of electric , but also to my lightening things up wherever I could. Like replacing a large # of steel fasteners with Titanium, aluminum or nylon.

This power system is more than necessary. It allows flights over 10 minutes (not necessary) , the amp draw is only 56, so the 125 ESCs provide more "headroom" or cushion than necessary, and the power is Phenomenal. 119 watts per pound. Much more than necessary or scale.

But this system works well, and enables a light, powerful B-25. So I used it. But the Main Reason I used it is it was free--the motors ESCs and batts--all free. How I got these free is explained HERE
(I actually paid for these years ago---when my son and I waived the "prize" money reimbursement he had earned. But we removed all the electronics when it went on permanent display at the museum since they didn't show or matter to the display purpose. So they have sat around the house all these years...and cost me nothing to recycle)
Last edited by softshell29; Sep 15, 2017 at 06:48 PM.
Sep 15, 2017, 06:11 PM
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Ziroli B-25 Electric---Where to Put the Batts

To get a lead-free CG I have two batts on top of the wing with their front at the LE. And 2 on a velcro tray below--further forward--in the positions shown by these pics

With this, the CG can be at the excellent location 5 1/8 inches back from the LE at the fuse. Other Builds mentioned a CG of 5 1/8 or nearby. BUT they failed to specify if this was with gear up or down

Since all 3 gear retract backwards and they are "heavy metal"---the CG shifts to the rear when the gear is raised. So I made sure my 5 1/8 worked with the gear UP. On some planes such a difference can be critical--life or death. I wouldn't be surprised if it works to measure CG with gear down, since the plane began as a fixed gear ship. But thats just speculation.
Sep 15, 2017, 06:24 PM
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Electric Ziroli--Batt Access

I was surprised when the prelim CG test showed the batts would not need to be in the cockpit or bombardier's area.

I didn't want to put them in the bombay and lose its function and need to invert the plane each flight to load batts. And my other posts explain the drawbacks of putting them in the nacelles.

Then I noticed the top machine gun blister could be the Access Hatch. This pic shows how I added 1 dowel and 1 RE Magnet to hold the blister in place after batts are loaded or unloaded. Nice thing about this is I can easily put the Machine Guns back in this blister---and any other scale detail desired. And its usefulness as an access hatch will be undiminished.
Sep 15, 2017, 06:37 PM
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Electric Ziroli---Cooling Paths

The motors are hanging out there in oversize nacelles with multiple cooling paths. But the batts ,ESCs and UBEC, are "bottled up" inside the fuse. They must receive a cooling airstream or the plane may perish.

One trick I use in bombers like these is to cut away one of glass segments--within the outline of its panel lines or frame. Even Super Scale, super picky guys don't see this "extra clean glass". Invisible cooling intakes and exits. This pic shows the one in the front and there is the same thing in the rear gunner's "greenhouse".

I have additional intakes and exits--like exit holes in the rear where they don't show and these 2 scoops behind the pilots heads. These sawed-off picnic spoons deliver cooling air directly over the ESCs
Sep 15, 2017, 07:36 PM
Onward and Upward
CatManDu's Avatar
Nice, love to see it fly.
Sep 17, 2017, 09:13 AM
Oh no, not again!
jhspring's Avatar
Always enjoy your threads, Softshell. Your work is meticulous and methodical. Lots for me to learn. There is a special kick in salvaging someone else's discard, isn't there?

Oct 23, 2017, 09:36 PM
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Thanks, Guys. And Jeff, You're right there are special challenges and rewards when starting where someone else left off.

Have 2 videos now. First shows how well it flies in "horizontal sock" wind. And both show electric gives more than adequate power.

The second vid, is actually an earlier flight, where we thought a flap or rudder were about to flutter off. These 4 surfaces were attached and hooked up via the old single- servo -plus -bellcranks, etc system which is weaker and sloppier than modern ways. I left these in since less essential than elevator and ailerons--which I redid--and would require way too much time and damage to structure to fix. I worried landing with one flap could be roll problem ... with one rudder no big deal. So I planned a flaps-up landing once we saw a piece leave the plane and determined it to be a flap. But false alarm. No piece fell off. The strange noise we heard evidently wasn't flutter at all, but still not sure what.

Had enough flight tests now. Time to put all the guns back on.

Ziroli B 25 Electric (0 min 37 sec)

Ziroli B 25 Takeoff and Flutter Alarm (0 min 43 sec)
Oct 24, 2017, 02:43 PM
An itch?. Scratch build.
eflightray's Avatar
There appears to be two sizes of the Ziroli B-25, 101" and 120", which one ?

Oct 24, 2017, 02:55 PM
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This 101
Oct 26, 2017, 08:31 PM
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Katniss's Avatar
Good information. That 101" Zirolli is not much bigger then my ESM at 95".

I had glow motors installed, but never felt comfortable with them as I had trouble getting them synced.
Plane never flew.
I'm now planning on electric and originally thought I'd go with power 160's on 10s since the plane weighed 32 pounds with glow motors.

Not sure what motors I'll go with now.
Oct 26, 2017, 11:49 PM
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Battery location

I missed your reason for not putting the batteries in the nacelles, what or why not ?
Oct 27, 2017, 05:40 PM
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I'm flying a 43lb OV-10 with 140's on 8s. Plenty of power.

Old Dawg
Oct 27, 2017, 07:02 PM
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Originally Posted by G limit
I'm flying a 43lb OV-10 with 140's on 8s. Plenty of power.

Old Dawg
140s?? What motors are those?

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