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Bird
11-09-2006, 08:57 PM
:confused: I would like to convert my High Start Bird of Time to electric. Does anyone have experience with this. It would save me from having to make all the mistakes myself.

TeslaWinger
11-10-2006, 01:40 AM
Hiya, Bird! It took me awhile to figure out how to do it - but try the blue toolbar at the top of the page. Select SEARCH. Type in - in quotes-

"bird of time"

It'll take you to all the conversion articles from months ago including my threads on the subject. It's my favorite plane! You'll like it. Add spoilers also and its the perfect sailplane.

I use an E-Flight 10 with a 30 A ESC and it climbs just fine- but a 3 cell lipo capable of 30 amps continous would be better than the NIMH I am using.

Heres some pix of the new motor installation and the video pod.

Enjoy,
TW

Franny
11-10-2006, 06:39 AM
Hi Bird!
I too have done a conversion. Check it out here: http://www.wattflyer.com/forums/showthread.php?t=3234 I also have a thred going about adding spoilers here: http://www.wattflyer.com/forums/showthread.php?t=11308 Unless you are flying at the salt flats or something, I think spoilers are a must. I'll be posting more about strengthing the center section of the wing and those spoilers as soon as I get back to it, but feel free to pepper us with questions!

Thanks,

Franny

photors
11-10-2006, 06:46 PM
Are you using the ARF or the wooden kit?

Bird
11-11-2006, 12:44 AM
Are usinf the ARF or the wooden kit?
This is a built up wooden kit. I have a new kit which I will build and try to incorporate whatever I have learned in the new build.

photors
11-11-2006, 01:44 AM
The plane at the Nats was a wooden kit and appeared to be much easier to convert. You really have to squeeze, even with LiPo's.

TeslaWinger
11-11-2006, 06:06 PM
The plane at the Nats was a wooden kit and appeared to be much easier to convert. You really have to squeeze, even with LiPo's.

The ARF was very easy to convert. The HARD PART was cutting off all that steel weight epoxied into the nose! THAT took some nerve- but worked out perfectly.

Squeeze is right! Even for all its awesome 10 ft span the fuse is kinda small- but still large enough for anything you might need to power it with- it just takes a bit more planning! I moved the rudder servo to the next to last bay and the RX all the way back. That leaves me plenty of room for any battery I want to use.

I just had a magic noonday flying session with mine as a warm front aproached. I had to quit when the wind got too high but was some very bouyant air for the hour I flew it. It was like a spring day with lift everywhere- and a hawk who joined me to scratch at low level along the hill- and made me realize (again) just what a great flying glider this is!

I strongly recomend converting this one whether its the kit or the ARF.
TW

PS: FRANNIE- How ya like it? I lost track of you and your bird for a while there! I'll have to try some of that Salt Flats flying- like I did today without spoilers! Yep! She needs 'em! I wouldn't cut into the D cell of the wing to mount the spoilers but instead put them right behind it.

Lift
TW

Bird
11-11-2006, 09:21 PM
Thanks for the info. From the picture, I can't make out what the motor is.
Thanks:)

photors
11-11-2006, 09:57 PM
The secret to removing the metal plug is not to cut it off, but drill a 1/4 hole in the nose and insert a punch until it contacts the plug. Have someone hold the plane while you give the punch 2 orb 3 really good whacks. The plug is only held in 2 places with hot glue. This took me 5 models to work with. I am working on E-BOT 6

photors
11-11-2006, 10:04 PM
AU contrare. When you switch from a 10 cell nicad or Nimh pack to a lipo it becomes very tail heavy. My current E-BOT#6 will require most of the gear to be forward as possible, to eliminate having to add nose weight. I am using a Permax BL-480 brushless motor with a 40 amp BEC, a 3S 2000mah lipo pack, and a 14x7 graupner folding prop.

Franny
11-11-2006, 10:05 PM
I used a quarter inch or so of the plug as my firewall. I needed the extra weight to balance anyway.

Tesla - I do like it, but I haven't got to fixing the centersection or adding the spoilers yet. There is no way I would be able to fly it where we do without the spoilers, but it sure is a sweet bird!!! I'm glad you are enjoying yours so. I saw your pictures and your rig. pretty cool! My camera rig in on my 1/2A Viking. So nice to rocket up and then chill for a while and take tons of photos...

Franny

TeslaWinger
11-11-2006, 10:46 PM
Chill she does! I had it parked in the sky downwind and it just sat there in the same place for a long time. As the wind picked up it actually flew backwards when I had it trimmed for the slowest flight! The thermals were cycling thru like freight trains. I have to say I love the way it rises in lift while in a level attitude- like it has a string at the AC pulling it straight up!

I've done lots of aerial video but the digital still cams take sharp photos that look better than stills from video. I'll be trying that soon!

The cool thing about your steel firewall is that you can drill a gazillion lightening- and cooling holes- in it due to its strength.

The internal mount limits the power you can run since the cooling is much less than an external mount- but sure looks clean! But 30 seconds of climb is all you need with a big motor then it has a very long time to cool!

NOW HE TELLS ME! I wondered if the plug could be knocked out of there- thanx, Photors! That would have been a different path!

Great thread for a great Bird!

TW

Up&Away
12-10-2006, 09:58 AM
The secret to removing the metal plug is not to cut it off, but drill a 1/4 hole in the nose and insert a punch until it contacts the plug. Have someone hold the plane while you give the punch 2 orb 3 really good whacks. The plug is only held in 2 places with hot glue. This took me 5 models to work with. I am working on E-BOT 6
Got any pictures of that procedure?

Bird
12-10-2006, 09:00 PM
I am converting a Bird of Time Kit to electric. I have a GREAT struggle with controling it at takeoff. The +2 degree incidence of the wing seems to produce a lot of "flare" as speed increases. I respond with down elevator and sometimes, I get it right but usually, it is touch and go. Having numb thumbs is no help either - not from the weather, my thumbs seem to be kind of numb even on hot days - or maybe that is my hand-eye coordination. I put lots of down-thrust on the motor and that may have helped a little.
What have others found? Is there any magic or will I just have to try to get my thumbs and my eye together.
Thanks in advance.

TeslaWinger
12-10-2006, 09:56 PM
Bird, anytime you put a lot of power on a slow flying glider and pull it faster than trim speed, it will nose up.

It helps to climb it out aways then turn so it is going left to right (and back) across your field of vision. It makes seeing the fuselage climb atitude easier so it doesn't take too big a bite and drop a wing!

Throttling back to a point where the overthrust doesn't upset things so much is also an option- and leaves more power in the pack for later with a climb that takes longer- and is easier to trim in climb- but at a much reduced amp draw.

A few notches of down trim helps as well as riding the climb angle all the way up with that elevator stick thumb! Downthrust sure helps it from tailstanding too! Reducing the throttle to 2/3rds or so will make your takeoffs easier. Throttle management becomes critical when an abundance of power is available!

I have about 5 degrees downthrust and 5 right built in. Coulda used more downthrust too!

I just installed a high power 4200ma 3S2P Thunderpower lipo for the BOT to replace the 1900ma 8 cell NIMH I had used. Roughly the same weight but well over twice the capacity and far higher voltage that doesn't sag much under the 30 amp max load.

The E-Flite POWER 10 is down to a 10x6 folder to keep it under 30 amps (30 Amp JETI Advance ESC) and shows 310 Watts at full throttle on the WattMeter with the battery well worn, higher when fully charged! It hit 376 Watts briefly fully charged with this prop! The motor is rated to 375 Watts! This is gonna be fun!

Bird
12-11-2006, 02:44 AM
Thanks TeslaWinger. Your note reassures me that I am struggling in the right direction. The main problem is in my thumbs. I have a AXI 2820/12 motor with TP 2100 3S battery. That was plenty adequate for several lifts to as high as I wanted to go. Previously, I had used TP 2100 3S2P which weighed more but didn't seem to hurt the glide. My problem there was that I had such long flights that I got a cramp in my neck. My prop was Graupner folding 12x6 (maybe it was 12x7 don't remember).
I went all the way to +10 degrees of down-thrust but I couldn't see that was any better than +5. I did not have any right-thrust and I didn't miss it.
Unfortunately, on my last flight, I stalled in my struggle to get altitude and smashed BoT up well beyond repair. I did salvage one of the wing however. Motor and battery were not damaged and I have started building 2 mor for next summer.
Thanks again.
Bird

Up&Away
12-11-2006, 11:16 AM
Do (did) you launch yourself? It helps if someone else does the launch, so you have both hands on the Tx.

Bird
12-11-2006, 01:55 PM
On my last and most memorable flight I did launch it myself although I had had it launched by a friend on some other flights and had done it myself on others. I agree that it is easier if someone else does the laaunch. The first 40 yards were uneventful but as the plane gained speed, the flare from the +2 degree incidence became a problem. I think I was not quick enough to get down trim on the stab and I got into a cycle of stalling because of too much flare and stalling because I cut back on throttle. Soon the plane was too far away to see what I was doing clearly and a bad thing happened (it crashed). I think I have learned a lot about the launch but my knees will be shaiking when I launch next spring with my new BoT. I am building two BoT. I don't think I am pessimistic: I just want to be prepared.

TeslaWinger
12-15-2006, 05:19 AM
Bird, sorry to hear ya munched 'er. Glad to hear you are already building more! :D

I love to hand launch planes, especially big E gliders. Maybe because I flew hang gliders for many years- it seems completely natural! Use a neck strap with the tx and you will never have to worry about dropping it on launch or worry about loss of control while launching.

With the glider in my left hand (translate if you are normal) I reach across with my right hand, set 2/3s power, return my rt hand to the E/R stick, and toss her slightly nose up smoothly into the wind. The power does the rest.

If you get into a stall on climbout while still low, keep the power on- it makes the stall/dive far less severe and you can level it with the elevator quickly with all that prop breeze on the tail and thrust for the wing.

Anytime it gets into an unstable situation, level the nose first THEN reduce power to keep out of the Stall/Dive cycle!

The numb thumb situation will require you to practice with different grips- ie- with thumb and a finger, or two- Easy with a neck strap. It removes all strain from your hands since you no longer have to support it! I lost a fingertip and still play guitar- find a way to compensate. Having an extra finger gives you more positional feedback since they aren't needed to support the tx. :D

Until Spring get lots of sim time to wire your reflexes in. It really is a good confidence booster and gives you real skills!

We all remember shaking knees. :D I had to sit down where I was after landing since my legs were too weak to walk to the plane just yet! :D It'll pass and you will get your composure back as you build some Time on this beautiful Bird. After a half dozen good flights the shakes are history! :D

Enjoy,
TW

Bird
12-15-2006, 02:41 PM
Thanks TeslaWinger for the reassurance and advise. I think your pictures are awsome. I gather you like the simulators. Do you advise that I get one? Could I get the simulator to give me the launch problem that I have in order to practice the hand-eye-brain-thumb coordination I need?
My new BoT has one wing almost finished and I can see that Santa is bringing me another kit. I guess I have been a better boy than I thought or maybe my wife just doesnt think that one BoT will see me through next summer.

TeslaWinger
12-17-2006, 05:18 AM
Bird, I have the RealFlight G2- just before the G3 came out :D I am a strong believer in sims for building the skills you need to fly RC well.

I fly the RealFlight Bird Of Time with a power system, Aveox, I think, and it is fun with the thermals turned on! The best soaring simulator I ever flew was Hang Sim, made for Hang Gliders and Ultralights which modeled the thermals and slope lift beautifully, far better than RF or anything else I've ever 'flown.'

The only problem I have is that the computer model BOT tends to overbank and tighten steeply in a turn, requiring constant 'highstick.' The real plane has far better Spiral Stability (almost neutral) in turns and I haven't found a way to correct it in the program to better reflect the actual handling characteristics.

One cool sim thing is the ability of actuating flaps for spot landings on the sim. Imagine catching a thermal on final aproach and soaring it to cloudbase- easy when the thermals are turned up high.

Today for real with my Aspire E glider conversion, starting at 30 ft in a small spot of lift, I turned and turned again into the lift and took it so high I had to spin it down to where I could see it again!!!! Reminded me of a 'low save' I flew on the sim! With practice like this on the sim, you'll be ready for when the conditions are right for magic flights like this!

Having a 'real' RC Sim controller in your hands helps to get the right kind of practice to make your reactions translate easily to the actual experience and feel of it. Do your learning and crashing on the sim- then go have fun!

If you can take off, fly around and land with a sim, you are going to be fine when you go fly again!

The wife is wise. Keep her! :D
Regards,
TW

John F Hendry
10-04-2014, 12:16 AM
The secret to removing the metal plug is not to cut it off, but drill a 1/4 hole in the nose and insert a punch until it contacts the plug. Have someone hold the plane while you give the punch 2 orb 3 really good whacks. The plug is only held in 2 places with hot glue. This took me 5 models to work with. I am working on E-BOT 6

Thanks for the info... that's great UNLESS you have also glued in the lead shot and have that to deal with too... and I did a good job prepping it for gluing. ERRR! Starting with a new fuselage seems warranted especially after how I did the nose and canopy to catch it. Servos and receiver need to go back behind C/G and I'd look into using a bell crank (again, used tail servo to avoid the hassle) for the elevator to lighten the tail and use carbon control rods. Weight is the issue to reduce AMAP going electric IMO and if I was building the wing again I'd replace the aluminum wing joiners with carbon fiber. Make no mistake this is not the original wood kit that is better in many ways.[popcorn].

cliffkot
10-04-2014, 05:09 AM
Thanks for the info... that's great UNLESS you have also glued in the lead shot and have that to deal with too... and I did a good job prepping it for gluing. ERRR! Starting with a new fuselage seems warranted especially after how I did the nose and canopy to catch it. Servos and receiver need to go back behind C/G and I'd look into using a bell crank (again, used tail servo to avoid the hassle) for the elevator to lighten the tail and use carbon control rods. Weight is the issue to reduce AMAP going electric IMO and if I was building the wing again I'd replace the aluminum wing joiners with carbon fiber. Make no mistake this is not the original wood kit that is better in many ways.[popcorn].

I am also building an e BOT and have given some thought to the tail weight issue. After some investigation, I rejected the idea of moving the tail servo. To really benefit, you need to use the lightweight carbon rods for both servos as the existing metal rod is quite heavy. Moving the tail servo alone and replacing it with a bell crank and new rod, will only save you about 5 grams in back. (Multiply that by about 5 to get the total weight saving for the model) But the problem with the carbon rods, as one of the fellows in this group pointed out, is that they have to be supported every few inches to keep them rigid. This is a difficult proposition for an already built fuse. I finally decided that I'd use an HS-65 carbon gear servo for the elevator. Good torque, very lightweight, less hassle.

My 2 cents.

Cliff

firemanbill
10-04-2014, 01:33 PM
Ok so I saw one of these beauties fly last weekend at EOT and have been dreaming of them ever since.

I got the kit so I can build in spoilers and set it up for electric power from the start.

Been reading up on all the threads here and other places so feel like I have a head start already!

I'm excited!:D

cliffkot
10-11-2014, 03:49 PM
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

John F Hendry
10-12-2014, 06:23 PM
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

Thought I'd mention another post on the BOT electric conversion stated the nose weight (solid metal) weighed 9 oz and as I recall another many years ago said it was even heavier and that's the one I think is in mine as it only took an oz or so of lead to get the CG correct with a 9 gram servo in the tail. There are reports the solid weight is steel not lead but some at least think theirs is lead, steel shot in glue, as well as lead shot in glue, so there are some inconsistencies with what has been reported used. Sounds like the solid steel metal plugs come out the easiest. I'm wondering if the newer ones are using the steel shot and glue.

I'm pretty sure mine has the solid metal plug but I did such a wonderful job of fiber glassing it in using epoxy reinforcing the nose for "hard" hand landings it will be a real bear getting out, easier to just cut off the entire nose and glass on a new nose and use the original as the mold.... have the SK3 840 KV glider motor and Hobbywing Funfly 60 amp OPTO ESC with 3.5 bullets soldered on waiting to fly but still deciding on spinner and folding prop as well as how much time I'm going to award this project. Have a second kit unassembled and may use it's fuse and have two, powered and glider. But there's the issue of needing to glass the center section of the wing so maybe change it's color as I want transparent colored panels for visibility, modifying the rudder to lighten the tail and increase its effectiveness by going to a balanced rudder that has the entire top move helping the rudder servo out some and a ton of other stuff I've thought about doing to it over the years so winding down on ideas to go with. But sometimes that the best part of the hobby... [popcorn]

cliffkot
10-12-2014, 09:49 PM
Thought I'd mention another post on the BOT electric conversion stated the nose weight (solid metal) weighed 9 oz and as I recall another many years ago said it was even heavier and that's the one I think is in mine as it only took an oz or so of lead to get the CG correct with a 9 gram servo in the tail. There are reports the solid weight is steel not lead but some at least think theirs is lead, steel shot in glue, as well as lead shot in glue, so there are some inconsistencies with what has been reported used. Sounds like the solid steel metal plugs come out the easiest. I'm wondering if the newer ones are using the steel shot and glue.

I'm pretty sure mine has the solid metal plug but I did such a wonderful job of fiber glassing it in using epoxy reinforcing the nose for "hard" hand landings it will be a real bear getting out, easier to just cut off the entire nose and glass on a new nose and use the original as the mold.... have the SK3 840 KV glider motor and Hobbywing Funfly 60 amp OPTO ESC with 3.5 bullets soldered on waiting to fly but still deciding on spinner and folding prop as well as how much time I'm going to award this project. Have a second kit unassembled and may use it's fuse and have two, powered and glider. But there's the issue of needing to glass the center section of the wing so maybe change it's color as I want transparent colored panels for visibility, modifying the rudder to lighten the tail and increase its effectiveness by going to a balanced rudder that has the entire top move helping the rudder servo out some and a ton of other stuff I've thought about doing to it over the years so winding down on ideas to go with. But sometimes that the best part of the hobby... [popcorn]

My BOT nose plug was steel shot. It is lighter than what was used in the past because GP have either lightened up the FGlass in the rear end or given the builder the option of adding more shot or a bigger battery for balance. Hopefully it is the latter because the fuse is a bit fragile in back as it is.

Although the SK3 750KV would have been the proper choice for this model, I also chose the SK3 840KV in the Glider Drive version mainly for the rear connectors. I wanted to get the motor as far forward as possible for balance reasons and prefer not to have a wiring "bump out" for esthetic considerations. I intend to round out the fuse. Hope that HK will eventually have a 750 KV Glider Drive that I can drop in. They did promise more motor versions in their introductory video.

Cliff

PS I discovered quite by accident that a large 1 - 1/2 inch steel washer is perfectly sized for use as a motor mount. I plan on layering it with a G-10 FG 1/16 inch spacer. All you have to do is push it in, add a little heat, and presto, a perfectly rounded fuse. I'll also drill air holes to match the motor's. It'll be a perfect fit.

Yakfishingfool
10-13-2014, 07:36 PM
Photo Cliff!

Bushmen777
10-14-2014, 06:39 AM
Like that bird

John F Hendry
10-14-2014, 12:39 PM
My BOT nose plug was steel shot. It is lighter than what was used in the past because GP have either lightened up the FGlass in the rear end or given the builder the option of adding more shot or a bigger battery for balance. Hopefully it is the latter because the fuse is a bit fragile in back as it is.

Although the SK3 750KV would have been the proper choice for this model, I also chose the SK3 840KV in the Glider Drive version mainly for the rear connectors. I wanted to get the motor as far forward as possible for balance reasons and prefer not to have a wiring "bump out" for esthetic considerations. I intend to round out the fuse. Hope that HK will eventually have a 750 KV Glider Drive that I can drop in. They did promise more motor versions in their introductory video.

Cliff

PS I discovered quite by accident that a large 1 - 1/2 inch steel washer is perfectly sized for use as a motor mount. I plan on layering it with a G-10 FG 1/16 inch spacer. All you have to do is push it in, add a little heat, and presto, a perfectly rounded fuse. I'll also drill air holes to match the motor's. It'll be a perfect fit.

I assume you are referring to the 42mm Turnigy Aerodrive SK3 - 4240-740kv Brushless Outrunner Motor as I didn't see a SK3 750KV. But I agree,
the Glider Drives are much better suited for the BOT. For pure gliding I plan on using a smaller prop anyway so it should work out well but it would be nice to have an extra 5A just in case I want to use it in something bigger that floats;-) Thanks for the info on the 1.5 washer. Good thing about using steel over wood to mount it is you have some more heat sink working in your favor getting cool air.

Still deciding what fuse to use. Really dislike undoing what I've already done so I'm going to take the new fuse and drill a hole and heat up the fuse to soften the glue and give it a few good whacks and if the plug comes out easy I'll use it. Otherwise I'll just cut off the nose on the RTF fuse and make a mold and a new noses for both for when and if the time comes I need the 2nd fuse. I got the second kit for parts and that was around 2001 just after some issues were corrected with the wing and the price was even lower using my Tower Dollars and a discount. At that time nothing came close to the BOT ARF for the price. Still an amazing deal.

Yakfishingfool
10-14-2014, 01:28 PM
Hey Cliff, lets see photo;s of that washer installation. Scott

cliffkot
10-15-2014, 10:29 PM
Hey Cliff, lets see photo;s of that washer installation. Scott

Probably won't get to the project for awhile, but I will post photos as I go along. You guys will be the first to know!

Cliff

Riff Raft
10-28-2015, 02:27 AM
After a great deal of research purchased a bot arf and converted it to electric assist. But when finished was discouraged to find that I was now 14ozs over the arf weight of 60ozs Don't know how it happened when so many others were considerably less
Mini servo in tail
Pull pull cable system on rudder
Spoiler system
2200 3 cell lipo
15 size e flite outrunner
40 amp esc
12x6 apc folding prop
The first flight was insane to say the least with a motor that was obviously overpowered pulling the nose up and then over on its back. I don't think the bot was built for aerobatics but it will perform. This all occurred with about 6 degrees of down thrust. But once the motor was shut down and the plane trimmed out it flew majestically and on approaching landing just refused to lose any altitude. Thank goodness for spoilers!
On subsequent flight held the motor to about 60%and all was fine. Also realized that bad things would happen if you chopped the throttle on climb to go to glide. A gradual lessening of throttle made the transistion so much nicer.
What a beautiful plane in glide.
Looking back I wished it hadn't been so heavy but it certainly will penetrate. In additionI would choose a smaller motor.
Looking so forward to putting away my high start. Can't wait to convert another.

John F Hendry
10-29-2015, 02:44 AM
After a great deal of research purchased a bot arf and converted it to electric assist. But when finished was discouraged to find that I was now 14ozs over the arf weight of 60ozs Don't know how it happened when so many others were considerably less


Wow... when you subtract the 8+oz weight of the nose plug and 2+ oz additional ballast needed that's well over a third of the complete RTF spec weight of the BOT added including a 75 gram RX battery, well over a pound added and you used a 1+ oz lighter motor than many use. The one I picked is about 183 grams to replace the 238 gram nose plug plus 2+ oz additional ballast used leaving plenty over for the folding prop. Saying the lipo battery is 210 grams and the ESC is 60 grams that's only about 9.5 oz added to the 3.75lb RTF specs where some of ballast left out should lower it some.

I don't see where the weight came from unless you added a lot of weight to the wing in adding the spoilers where 18 grams would cover the servos needed. Did you weigh what you added to the wing? Did you glass the center section of the wing? Even stock that's something I planned on doing but the wing spar end caps have the grain running horizontal in mine and wondered if Dynoflight fixed that yet. Were the end cap's grain vertical in your wing?

Are you sure your scale is correct? I'd have to get my notes but when I did the C/G weight calculation to see where I was at using a 2600mAh S3 60C battery and HW Funfly 60A ESC the added weight was not much more than I'd ballast for anyway setup for light 10-15 mph winds. I just don't see how you could add almost a pound after removing so much weight in metal to start with. You should weigh your wing and post it's weight.

Riff Raft
11-04-2015, 03:16 AM
A short history is in order in reference to the previous post.The first flight a year ago did not go well. Inexperience sent the plane rocketing skyward and soon out of control. The result was a broken wing at the centre joint. After repairing it last winter glassed the centre section and recovered the wing.
The spoiler is cable driven by a mini servo just forward of thr leading edge.
The rudder is a pull pull system operated by a servo below the cog
And the stab is operated by a 9 gm servo in the tail.
With the battery motor and esc as far forward as possible
As requested the wing with spoiler weighs 31.5 ozs the battery weighs 6.5 and the esc 2 ozs.
After all this it still requires 4 ozs of lead behind the motor.
At 74.5 ozs it's a porker but I'm still happy about its performance

John F Hendry
11-05-2015, 11:26 AM
Hay Riff now I see why you still need weight added to the nose. I just weighed my BOT wing which is stock and the tip panels both weigh exactly 162.5 grams and the center section that is the upgraded wing from the first lot that were breaking is 307.2 grams so all total the complete wing weighs 632.2 grams or 22.25 ounces leaving 37.75 oz left for the weight of the fuse at a flying weight of 60oz. So you have added 265 grams or 9.4 oz to the wing. Well... that's a lot of weight to add for a set of spoilers;-) And with the wing repair and center sheeting it's mostly behind C/G.

So take away the 4 oz nose weight the added electric power supply and battery normally replaces and the 9.4 ounces added to the wing and you can see where the weight came from. But don't let your mind get in the way knowing it's over 60oz as the BOT is a BIG glider and adding 4 oz would be hard to notice and 8 oz would be about where I'd expect to see a noticeable change from 60oz (it's more noticeable at lower wing loadings) so another 6 oz is not all that much from there and remember your sink rate will be decreased but only because you fly faster as your L/D angle will remain the same as long as you did not add any extra drag to it with adding the weight. In the wind the added weight won't hurt one bit and you'll be able to move around the sky better looking for lift.

What you won't be able to do is remove the built in 14 oz of ballast for parking it in light thermal conditions and you'll come in faster to land but not as much as you might think so don't let it affect your flying. Nothing is "wrong" you're just well ballasted;-). Now you have spoilers so that makes things a lot easier coming in to land. Adding 14 oz to a BOT does not make it a "porker"! It just makes it fly faster and have better momentum for punching through turbulence coming in to land at the expense of a reduced climb rate under power. And since it's still a glider and not a 3D power plane that's not much of a trade off where adding weight is how you trim for the conditions resulting in a better sink rate than pointing your nose down to keep your air speed where it needs to be. So have fun and fly safe...

Riff Raft
11-05-2015, 12:15 PM
Still disappointing I thought my building and repair skills were better than that! But on the up side here in the Maritimes most of our flying is done in wind. Seldom do you get a day that's calm, and that's why slope is the more popular sport.I had a old Riser that was overweight too and it flies great. My brother with a in spec Gentel Lady cursed it untill the day it died.
My next project is to electrify my Lovesong. It has been resting for many years because there is not the room to launch it.
When I finish that though I'll just hide the scale. At least that's what my wife does. Comes back to the old saying "what you don't know won't hurt you"
Thanks for your help
Charlie