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Bird of Time Electric Conversion

Old 10-27-2013, 12:18 AM
  #176  
SuperCub Man
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I measured the diameter of the motor case and then allowed a little bit more for it to spin and to allow for my inaccuracy in mounting the motor in the center of the firewall. This is how much room you need INSIDE the fuse.. Use a set of compasses or something to estimate this location inside than cut 1/4" in front of that. When you make the firewall to this estimated size and pull it through the fuse, molding the fuse with your hand as you go, it will become round, or round enough. Sand the edges of the firewall to allow for the taper of the fuse. Try pulling it through (drill motor mount holes first) and if it is too big or too small make another, checking that there is room for the motor. This will by necessity therefore be as far forward as you can place the motor. Much easier to do than explain!!

Last edited by SuperCub Man; 10-27-2013 at 03:21 AM.
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Old 10-27-2013, 01:28 AM
  #177  
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Very helpful! Thanks!!!
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Old 10-27-2013, 11:00 PM
  #178  
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Torque on a sail plane is not that important and I have built them with none in there, but down thrust is. You have a high lift wing and it will want to lift on you and if you do not put some down thrust in, it may loop and you may not have enough elevator to stop it. I normally put about 6 degs in and in most cases that is plenty. It's not that hard to do and is really nice not to have to fight it on the climb.

Ed
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Old 10-28-2013, 02:30 AM
  #179  
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more great info!
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Old 11-03-2013, 10:35 PM
  #180  
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OPened my ARF and the fuselage, right in front of the verty stab is cracked...right along the seam. Was going to epoxy it over to close it but have read about the foam int he tail info here. Was it a spray can or ??? How did you do it and keep it out of the vertical stab region. I;d love to pump a little through the rear access hatch to firm up and that thinner boom area. Got all the electronics, waiting for a 40mm aluminum disk, want to round the firewall but just don't understand how you take it from oval to round I assume with the nose cut off the glass is thin enough to compress it to oval? Also...have not opened the wing center piece but is there a place to run a servo lead to get it into the fuse? Thanks. Scott
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Old 02-16-2014, 11:29 PM
  #181  
Desertdog
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Default Some good advice?

Hello all, I entered this post at the beginning after sundevil started it and I have left for new grounds (a 3.2 pulsar pro electric) I log on once in a while to see what is happening and some guys seem to get lost when some one else does something different and they all follow like sheep.Sundevil got it right in the first place and I followed and made it a little better? If I had to do it all over again I would put in the carbon fiber strips in the rear fuse and use a mvvs 500 watt 40 4.6/840 motor and a 14x8 folding prop along with a 45 amp controller. This is a perfect combo in my pulsar as the motor is very narrow and you do not have to cut as much off the nose to set the motor as far forward as you can get it and you will also need the extra weight. You will also need some stick on wheel weights and place them as far forward as you can get them also because the more weight you can get forward the less weight overall.The best thing about the mvvs motor is the electric wires exit out the back for an easy hook up. Forget about cooling holes in the front of because you are only using the motor to get to altitude and shut off about 8 seconds and this quality motor does not get hot.

Best of luck to all of you.
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Old 02-27-2014, 08:59 AM
  #182  
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I flew mine with a .15 on top of wings for years. It is more than enough to put this airplane out of sight.
While flying I lost sight of mine, fortunately others guys in the field saw it and I was able to recover it.
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Old 08-11-2014, 09:37 PM
  #183  
eosglider
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Default My e-BOT Conversion report

Happy to say I finally got around to doing this and love how it came out. Flies so nice, plenty of power. Will post pics of the result as soon as I can.

Equipment used for conversion:
Motor: Turnigy GliderDrive SK3 3858 - 4.6 - 840kv - It's an encased outrunner so no need to worry about leaving space for motor cables besides the motor.
ESC: Turnigy Plush 60
Battery: Zippy Compact 4000mAh 3s LiPo
Spoilers: Cheap plastic pop-up brakes from HK (DO NOT USE THESE! See my note below)
Spoilers actuated by: In-wing HXT900 servos on each side.
Spinner: Used only the collet, yoke and 38mm spinner from the E-Flite Mystique 2.9m glider prop kit. Love the fact it's vented at the tip
Prop: 14x6 Aeronaut CAM folding blades from Esprit
Elevator setup: Used hacked cross servo arm as DIY Bellcrank setup instead of servo in rear.
Fuse reinforcement: Used spray foam insulation to stiffen up the soft fiberglass on rear of the fuse.

What I did to mount the motor:
- I removed BB's in the nose by enlarging the small hole already present and using a punch and hammer to chip away at them slowly.
- Once all BB's were out, I used a small dremel tool sanding drum through the canopy and through a larger opening I created in the nose and cleaned up obvious imperfections left by the epoxy BB block. Not to detailed, just rough.
- Cut out two 40mm round pieces of 1/16" ply and gorilla glued them together then soaked them in CA to use as a firewall.
- Made the proper motor mounting and a few venting holes and used the middle hole for the motor shaft to mount a 1/4 #20 bolt, 2 washers, and nut so I can eventually use it as a handle to stretch the fuse into being round instead of oval using the firewall. Just like SuperCubMan suggested.
- Sanded a slightly beveled edge on the firewall so it can conform to the inside of the fuse.
- Determined thrust line and roughly calculated what 3 to 5 degrees down and right should be for firewall mounting purposes.
- Pulled firewall into place making the fuse as round as possible while test fitting the motor several times checking for clearance, sanding, checking, pulling, measuring, etc. Nothing too precise, just eyeballing basically.
- Once happy with fit, used epoxy carefully as to not clog up the motor mounting surface and glued firewall into determined location. Roughly eyeballing the pre-determined position from previous step. Let it dry.
- Test fit the motor and sanded down the excess fiberglass fuse left in front of the firewall while test fitting the spinner combo for best fit.
- Once happy, bolted motor down, put ESC under canopy tray, connected esc to back of motor pins, and finished it up.
- I still needed a small bundle of bb's in a plastic baggie at the nose to balance it out believe it or not, even with that huge 4000mAh battery all the way to the front almost touching the back of the motor. Maybe because I reinforced the soft fuse boom in the back with some insulation spray foam (Blue cap one).

It's not exactly perfect, I really like the way the conversion came out. Specially the fact the fuse is now almost round without any need for an "Air Scoop". Ventilation for the motor seems plenty sufficient via the spinner's open intake tip and the vent holes in the firewall as the motor is barely warm when I bring it in for a landing. I also cut some ventilation slats in the rear of the canopy so airflow can escape.

Note on the spoilers I chose: I got them installed and working but I am not happy with them. I got what I paid for basically. They just don't want to sit exactly flush with the wing when closed so I'm sure they're adding a bit of drag/inefficiency. You tap them and although they are closed, they are loose and won't sit all the way down. Even at the max endpoints. Very low quality and it shows. At some point I might just pull them out and go with the tried and true balsa home made spoilers most people have been using. They definitely do help in dropping altitude but it's not drastic in my opinion. At least not with these even fully deployed.

As I said earlier, I'll post pics as soon as I can, but I am very happy with the conversion and how this bird flies. Thanks a lot to all of you here and those in the RCG community. Could not have done it without all your tips. Special thanks to SuperCubMan!
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Last edited by eosglider; 08-12-2014 at 11:18 PM.
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Old 09-13-2014, 04:53 PM
  #184  
renindy
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Bot sat for a while due to life events, etc. Dusted it off this month Sept 14. Initial flight I had forgotted i had a throttle elevator pmix programmed. Too much down elevator. And any rate, straightened it out on the next flight and the bird is a joy to fly. Great Power to weight ratio, and again I credit SunDevilPilot for leading the way into getting me back into R/C with something interesting that met my criteria. Thanks guys for keeping this forum clean and troll free. Enjoy the hobby, share the joy. My (now 6 year old daughter) wants to come out to the field with me, and *she* is egging me on to finish my Goldberg Cub. so -- its a win win eh?
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Old 09-23-2014, 02:12 AM
  #185  
Desertdog
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With all respect Keep it simple stupid.Just simple bulsa spoilers work awesome. And read rays sky bench rc article on small spoilers.

Good luck
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Old 09-23-2014, 03:24 AM
  #186  
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I ordered a BOT from my LHS that I'm planning to electrify. Went to pick it up last week but discovered (in the shop) that UPS had shortened the fuselage by a half inch so a replacement was ordered. However, I was rather dismayed at the absolutely horrible Monokote job done by the factory. All the edges were badly wrinkled.

Is this normal? Can it be fixed? I wasn't figuring on the additional cost of covering - iron, heat gun, material, etc. Plus I wanted the ARF because it was an ARF. What is it supposed to look like? I have never done any covering so your inputs would be appreciated.

Cliff
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Old 09-29-2014, 03:40 PM
  #187  
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Is there any real CG or weight benefit achieved by moving the elevator servo from the back to the front? When you consider the extra hardware needed, it seems it would be a wash, unless you could also eliminate some of the ballast up front.

Any opinions?

Cliff
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Old 09-30-2014, 02:10 AM
  #188  
Larry3215
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From a soaring viewpoint, its best to keep the extremities as light as possible, even if the over all weight goes up a tad. So it will be slightly better to have the servo closer to the CG even if you have to add extra nose weight to balance.

That only works if you are NOT adding back in a heavy pushrod. Some of the BOT's used pushrods that were very heavy. You would need to use a small diameter carbon rod in a Teflon sheath that didnt add much weight. Like what the DLG guys use. For example, on my Supra Im using a 1.5mm carbon rod in a matching sheath. Thats relatively light weight. The cg of the pushrod is also much closer to the models cg than a servo in the tail.

Now, that said, its not a huge deal either way if you are using micro servos to begin with. Many newer hi-end sailplanes move at least one servo to the tail. They do it mostly because the pods these days are very tight and the performance hit isnt all that big.

here is one source for rods and sleaves.

http://www.cstsales.com/carbon_pushrod.html
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Old 09-30-2014, 02:31 AM
  #189  
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Originally Posted by Larry3215 View Post
From a soaring viewpoint, its best to keep the extremities as light as possible, even if the over all weight goes up a tad. So it will be slightly better to have the servo closer to the CG even if you have to add extra nose weight to balance.

That only works if you are NOT adding back in a heavy pushrod. Some of the BOT's used pushrods that were very heavy. You would need to use a small diameter carbon rod in a Teflon sheath that didnt add much weight. Like what the DLG guys use. For example, on my Supra Im using a 1.5mm carbon rod in a matching sheath. Thats relatively light weight. The cg of the pushrod is also much closer to the models cg than a servo in the tail.

Now, that said, its not a huge deal either way if you are using micro servos to begin with. Many newer hi-end sailplanes move at least one servo to the tail. They do it mostly because the pods these days are very tight and the performance hit isnt all that big.

here is one source for rods and sleaves.

http://www.cstsales.com/carbon_pushrod.html
In thinking the build through the other day, I also made the same observation about the heavy push rod. That's what started me rethinking the idea of the servo move. A micro servo with carbon gears weighs 9 or 10gm. Even a mini is only about 14g. The supplied rudder push rod alone weighed 18 grams so I didn't see much benefit using another one plus 5 gms for a bell crank and hardware. If you had a net saving of an ounce, given the fuselage moment, you could save another 3 oz up front. That would be worth doing.

Thanks for the input. Still not sure exactly what I'm going to do, but at least my thinking is on the right page.

Cliff
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Old 09-30-2014, 05:49 AM
  #190  
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One other consideration is that, especially with the light carbon rods/tubes, they absolutely must be fastened down at least every three or four inches or you end up with too much slop/play in the surface.

With pod and boom fuses, like the Supra, thats relatively easy to do by running the rod/sleave on the outside of the boom. If you want to hide it inside the fuse, its very dificult to get it fastened down adequately all along its length.
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Old 09-30-2014, 11:47 PM
  #191  
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Originally Posted by Larry3215 View Post
One other consideration is that, especially with the light carbon rods/tubes, they absolutely must be fastened down at least every three or four inches or you end up with too much slop/play in the surface.

With pod and boom fuses, like the Supra, thats relatively easy to do by running the rod/sleave on the outside of the boom. If you want to hide it inside the fuse, its very dificult to get it fastened down adequately all along its length.
Didn't think about that one. I recall reading on one of the sights a post by a fellow who foamed his fuse. Is that a viable option? I would think it would add a lot of weight.
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Old 10-01-2014, 05:09 AM
  #192  
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Yeah, that foam is very heavy. It would completely negate any improvements you were trying to achieve and end up making things worse.

The only reason to do that would be if you had lots of slop and were not willing to fix it any other way.
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Old 10-01-2014, 10:31 PM
  #193  
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Originally Posted by Larry3215 View Post
Yeah, that foam is very heavy. It would completely negate any improvements you were trying to achieve and end up making things worse.

The only reason to do that would be if you had lots of slop and were not willing to fix it any other way.
Given all the options, I'll probably build with the servo in the tail. No sense reinventing the wheel. Securing the tubes inside would be difficult, although with the nose cut off, you might be able to insert some wooden support bridges and line them up for gluing. When I have time in life, I'll probably do the kit build. Then all options will be open.
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Old 10-11-2014, 03:51 PM
  #194  
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Default The Weight of a ARF Bird of Time Fuselage

The weight of a bare BOT fuselage is 12.05 oz. (342g). This weight does not include the portion of the nose cutoff to remove the ballast shot (20g). For further clarification , this is the weight of the fuse alone without ballast, servos, control rod(s), rudder, horizontal stab, etc. Just the fiberglass with integral wooden shelves and spacers.

The weight of the shot and glue plug is 8.4 oz (238g)

Measured on a Soehnle scale with accuracy of 0.05 oz. or 1.0 g.

Hope this data will be of help to all ARF BOT builders.

cliff
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Old 12-13-2014, 09:27 PM
  #195  
Desertdog
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loved my first bird but moved onto a pulsar pro 3.2 and there is nothing like it and fly it all the time.Ordered a sky bird from ray hays and am in the process of building that one on the bench and got the bug to build another arf bird, Used a hk 3536 1200 sk3 I had new in a box I had laying around with a 12x6 prop and 40 amp controller 3s 2200 batt. added some 3 bay spoilers. I do not bother with cooling vents any more on any of my sailplanes, one 12 second motor run keeps them up for an hour. The final weight came out @ 4.1 lb 65.76 oz
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Last edited by Desertdog; 12-22-2014 at 09:07 PM. Reason: spelling
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Old 01-17-2015, 05:39 PM
  #196  
AEAJR
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Now that you have this really cool e-glider, why not have some fun with it. Try an ALES, Altitude Limited Electric Soaring contest. We will be holding one in April on Long Island.

You can learn more here:
http://www.wattflyer.com/forums/show...827#post966827

If you are new at this you can fly Novice. Novice pilots fly FREE.
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Old 01-17-2015, 05:42 PM
  #197  
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Oregon to NY for a soaring contest.... might be a bit expensive.
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Old 01-23-2015, 03:36 PM
  #198  
Desertdog
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The arf bird of time is not an ales sailplane (far from it) and yes some of us can thermal better than even the pros with a good design like my 2m bird from skybench. If you move the cg back where the bot can really began to thermal it can do well with a good pilot. I'm not a contest guy and enjoy my own birds.
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Old 05-08-2015, 11:59 AM
  #199  
Desertdog
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no one has posted anything on this thread lately so I thought I would say a few thoughts about my arf. I just sold my 3.2 pulsar that I had for 4 years (awesome plane) but I liked my skybench sky bird better, I only bought an arf bird of time as an afterthought last winter.I took pains to build it light as possiple and do a good job at keeping it aerodynamic and it seemed to pay off. It is not a serious compeditor as to other sailplanes but here lately I have been flying it a little more in windy conditions and starting to like it and have changed my mind about how it thermals.I have spent some time really working small thermals and if you set the cg back (way back) it really can do well but when it falls of the step it will nose dive. For the most part the more I fly it I like it and in larger thermals it does very well.
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Old 05-10-2015, 12:32 AM
  #200  
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Default new to thread

hi there,
just came across this thread and it gave me the impetus to finish my BOT conversion. I chopped off the nose several years ago and it has just been hanging around waiting for me to figure out how to mount the motor. Well, thanks to y'alls ideas, I finally finished it. I did the round firewall, mounted a 3542 1000kv, 10/6 prop, 50A ESC and the hs-81mg servos are just ahead of the CG (40%). my initial balance used a 4S 2200 battery and 2.2oz lead. I then tried a 4S 3000 battery pushed forward and 3/4oz lead. Today I built a new horizontal using the kit plans (saved almost 40g) - had to remove the 3/4 oz, move the battery all the way back and it's still a tad nose heavy. AUW is about 63oz. still needs work to fair the nose and spinner a bit better and better access to the cockpit. will provide photos if anyone interested.
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