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Nov 28, 2004, 12:10 AM
Lee / RC Enthusiast
YarSmythe's Avatar
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Herr Engineering Cessna 180 Conversion


I haven't found anyone who has converted the Herr Engineering Cessna 180 to electric. I've been keeping up with this thread just to see if there are any tips I can use on my conversion.

The Herr Cessna 180 builds heavier since it was made for gas (20 oz. listed on the box). I think I can get it down to 15 oz. with lightening holes, micro-servos, and LiPos.

Here's a quick shot of what I have so far. It'll be nice to compare my final kit to a Mountain Models Cessna 180 when all is done.

-Lee
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Nov 28, 2004, 12:17 AM
Lee / RC Enthusiast
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The assembly of this kit is going well. This is probably one of the easiest "kits" (aka - box of balsa) I've ever built. The laser cuts are near perfect with all the pieces joining together very nicely. The wing is moving along quite smoothly and it appears I am not missing any parts.

I'm not too keen on the tail wheel assembly. It has the wire embedded in a very small piece of "balsa" rudder. Not strong at all. I'll have to reinforce it which will be the only step I'll deviate from in the instruction manual.

The current weight of the wing, fuselage, and tail pieces is 6.5 oz.

Photos and updates soon.

-Lee
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Nov 29, 2004, 08:17 PM
Lee / RC Enthusiast
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Finished the main structure of the wing. Wingtips still need to be installed and shaped.

My choice for a power plant is an Eflite 370 4100 motor geared to a 4.4:1 Himax Gearbox turning a 9x5 prop. Battery will be a 3S 1100mAh LiPo. Two main reasons for the motor decision are: Prop clearance & motor mount through the cowl. Motocalc says everything looks good. About 75% effeciency. I can deal with that.

I'm not going to cover anything until I have all the parts here. Still waiting on the gearbox. Once everything is mounted, I can hopefully find some options for dropping weight. I've been told that most Herr models end up tail heavy. This is a good thing since I am able to take off some weight with lightening holes through all the rear surfaces.

Here are a few more photo ops.

-Lee
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Nov 29, 2004, 10:15 PM
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Lee,

Looking great! I think you have the right idea about lightening the rear of the fuse and tailfeathers. If you wait until you have your electronics and power system in, you will be better able to tell about the C.G., and how much and where to lighten to get it right.

I agree, the Herr kits are great in terms of wood, fit, etc. Just wish they would make them a bit lighter. I actually prefer building the stick frame models, they are lighter, and I think more realistic.

How are you going to access your batteries? On my Cub, I ended up building a hatch in the bottom of the fuse, below the rear of the wing. Only problem with that is I had to make a sliding balsa battery tray that slid in a track on the inside bottom of the fuse, in order to get the batteries as far forward as they would go for balance.

Keep the pic's coming, I'm anxious to see this one finished!

AmpAce
Nov 30, 2004, 12:10 PM
Lee / RC Enthusiast
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Quote:
Originally Posted by AmpAce
How are you going to access your batteries?
That is a great question. One I've been pondering while I stare at the nose of this kit. The plastic canopy is typically glued on so removing the front hatch seems out of the question. I'd like to think there was a way to mount the windshield to a removable portion of the hatch...but it doesn't look good.

The simplest method is to mount the LiPo's on a velcro battery tray near the nose (where the fuel tank goes) and connect the battery with the wing removed. This means I'll have to remove the wing after each flight. This is a downside. But I figure: the bolts are easy to remove, there is no aileron wire to remove, everything is lightweight....not a big deal.

I'll consider a hatch underneath. It all depends on the CG.

Thanks for the feedback. I'll keep you posted.

-Lee
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Nov 30, 2004, 01:04 PM
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Removing the wing for battery access shouldn't be that big a deal, especially if you can make the wing lift struts easily removable.

I once had a Super Cub that required removing the wing. Sometimes it could be a pain, and I may not have flown it quite as much as a plane with easier battery access, but it worked, so that may be your best option.

Happy Building!!

AmpAce
Dec 05, 2004, 01:05 PM
Lee / RC Enthusiast
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Got the wing completed. I was looking into using SoLite for the covering...but it is not available at any LHS and since I was using white, I really don't like the balsa showing through. So, I decided to sacrifice added weight for opaque white.

Covering was Hangar 9's Ultracote. Never used it before. It's as heavy as Monokote...but I personally feel it is much easier to use. I can't believe I haven't tried it before.

White top with red stripes (suggested by friend). Red underneath. Looks cool but weighs almost 4 oz.

-Lee
Last edited by YarSmythe; Dec 06, 2004 at 02:18 PM.
Dec 10, 2004, 01:30 PM
Lee / RC Enthusiast
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Received my Himax motor mount yesterday. I started to install my Eflite 370/4100 motor but discovered the motor was seized. Ack.

Here's a shot of the temporary position of the gearbox. So far, everything fits "just right". The cowl has probably a little over 1/8" of play around the main gear. A few holes need to be drilled in the firewall for motor/wires/air and the motor mount will then be glued in place.

I can't proceed any further until I get a replacement motor. I still have no idea where the CG will be.

-Lee
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Dec 11, 2004, 12:11 AM
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Sorry to hear that you're delayed because of a bad motor. Keep up the good work! I had thought of doing a conversion of this aircraft and putting it in military markings. Absolute newbee to electrics, so I'm following your progress with great interest.

Brian C
Dec 11, 2004, 11:59 PM
Lee / RC Enthusiast
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Picked up a new Eflite 370 motor today at the LHS. However, before installing it, I decided to compare it with my trusty Himax 2015-4100 motor currently installed in my Eflite Ultimate (oddly enough).

Using a 3S 11.1 volt LiPo, Castle Creation Phoenix 25, an APC 9x6SF prop, and the Himax gearbox set to 4.4:1...here are my results:

Eflite 370-4100 no load current is 1.7 amps.
Himax 2015-4100 no load current is .7 amps.

Eflite 370-4100 WOT on 9x6 is 14.9 amps.
Himax 2015-4100 WOT on 9x6 is 13 amps.

Interesting. Same size motors and KV but the Eflite draws more current.

With that, I've decided to stick with the Himax motor instead. I feel it runs better anyway. Motocalc says a 9x5 prop would be best "all around" so I'll try to pick up the APC 9x4.7 SF prop. They don't make a 9x5.

Motor configuration: Himax 2015-4100 geared 4.4:1, CC Phoenix 25, and APC 9x6 or 9x4.7 prop.

Battery: Falcon Batteries 3S 1500mAh & 1100mAh LiPos.

Radio: Hitec Electron 6 w/3 Hitec HS-55's (aileron, rudder, elevator) on a Futaba 6EXA.

...more to come.

-Lee
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Dec 12, 2004, 12:07 AM
Lee / RC Enthusiast
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Photo of firewall and gearbox.
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Dec 13, 2004, 02:41 AM
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Lee,

Looking good! You are going to have her in the air soon, by the look of things! Have you had a chance to weigh things yet. I'll be interested in the all up weight, and also the C.G.

Happy Building!

AmpAce
Dec 17, 2004, 08:26 AM
Lee / RC Enthusiast
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Got the motor mount installed. I spent several days trying to figure out the best method. I opted to keep the stick long and let it butt up against the first former for strength (in case of nose impact). This works well and helps move the weight back a little...but I didn't compensate enough for down thrust. I'm about 5 degrees off based on the position of the firewall. If this becomes a problem I hope I can adjust it by modifying the gearbox and not tearing out the entire shaft.

Here's a photo before the canopy is installed.

Weight of fuselage with gearbox (as shown) is 6 oz. She's starting to get up there.

-Lee
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Dec 17, 2004, 09:01 AM
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pda4you's Avatar
Very nice!

Keep us updated. I just love the Herr kits....

Mike
Dec 17, 2004, 01:03 PM
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AmpAce's Avatar
Nice motor mount! If you need to make thrust line adjustments, you could probably just sand and shim the end of the stick to angle the motor in whatever direction you need.

AmpAce


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