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dynaflite bird of time

Old 12-20-2007, 11:39 AM
  #1  
mkpalmiero
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Default dynaflite bird of time

I'm thinking about building a BIRD OF TIME, can anyone who has built one
with spoilers give me some imfo on the spoilers. Such as: lenght, width, and location.
Old 12-22-2007, 02:23 AM
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G_eronimo
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Default RE: dynaflite bird of time

Hi mkpalmiero,

I just finished a BoT a few weeks ago. It has additional spoilers and an electric motor.

I started the kit more then 2 years ago as the original glider-version, but with spoilers already included. I think a "bird" of this size needs something to "escape" from a thermal. Then it collected some dust, waiting to be finished. Inbetween I decided to build in a motor. I cut off the nose and buildt in a plywood firewall. Unfortunately the interior of the fuselage is too small up front for the battery (4S LiPo), so I need additional weight.

The spoilers are in the inboard wing part, where the ribs can be seen (about 4 "spaces" long). I will take a photo tomorrow at daylight, with spoilers extended. I can't remember the brand. They are made of aluminum.
There are some "rules of thumb", I have to look for that too. The position should be around the highest part of the profile (~ 25-35% of the depth). I put mine just behind the spar. The position along the wing should be, where the "wake" from the spoiler doesn't affect the elevator. There is very turbulent air, when the spoiler is extended. If it hits the elevator, it might cause vibration.
Each spoiler has its own servo. A better build-up might be a wing with a central part and 2 outside parts (I think, that is how the BoT ARF is build). Both spoilers could then be moved by one servo only.

I got 2 flights up to now. Some problems with my transmitter, as the Hitec Eclipse 7 does not have a 3 way switch programable for the spoilers. And channel 3 is used for the motor. So I had to use a rotary knob for the spoiler, which is unergonomical. The plane flies very nice. Good landings on the spot possible due to the spoilers.

Uli
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Old 12-22-2007, 04:14 AM
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mkpalmiero
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Default RE: dynaflite bird of time

G eronimo: Thanks for the lmfo, I was thinking of operating them both from 1 servo in the fuselage via tubes and
strings with rubber bands to pul them closed. I sounds like the spoilers you used are the ones Grauphner makes/
thanks again for the imfo.
Old 12-22-2007, 04:16 AM
  #4  
mkpalmiero
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Default RE: dynaflite bird of time

G eronimo: Thanks for the lmfo, I was thinking of operating them both from 1 servo in the fuselage via tubes and
strings with rubber bands to PULL them closed. I sounds like the spoilers you used are the ones Grauphner makes/
thanks again for the imfo.
Old 12-22-2007, 06:40 AM
  #5  
Sailplane
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Default RE: dynaflite bird of time

Hello G_eronimo and others that may want to help me,

I'm also planning to purchase a BOT (ARF) and converting it to an electric. It looks like yours has a balsa fuse; I believe that those that are being sold now have fiberglass fuses with lead weights in their front ends.

I have a new Phasor 30 (Brushless) to be placed in it w/out any reduc gear, but from looking at your two pics and some others that I found in a review in another RCU forum, it appears that there isn't going to be enough room in that fuse to put in all of that other stuff like the motor, ESC, Rx, standard server for elevator, micro/mini servor for spoiler, etc. What do you think?

Also, it looks like you found a pretty neat way of mounting your motor and sliding it into the fuse; anyway, it appears to me that that is the procedure that you used. If it is, that's pretty darn original! Perhaps, someone can help me out with the mounting of the motor in that fiberglass fuse. The EP sailplane looks great!

G-eronimo, can you give us more details on your brand of motor, reduc gear (if any), motor size, brand of ESC and Rx, how you installed the three servos (1 elevator & 2 spoilers), brand of spoilers, and anyother ideas that you came up with in your modification. Also, could you have placed a single spoiler centered over the fuse? What was the total all-up weight. Gees man..., how in the world did you fit all of the above, plus a 4S LiPo, in that tight space.

One last question: Can it thermal?

Many thanks,

Ernie (AKA Sailplane)



Old 12-22-2007, 08:48 AM
  #6  
avroarrow
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Default RE: dynaflite bird of time

Hello Ernie, I have converted a BoT arf to electric. I first cut the nose off the fiberglass fuse with a diamond chipped cut off wheel, mark the fuse aproximately where the expoied steel nose balast stops,then cut carfully . If you use masking tape around the area of the cut,this should reduce the chipping of the gelcoat of the fiberglass fuse when cutting through the nose. I made a ply firewall to mount the motor, i used a 2408 motor, 30amp esc, 2400 mah 3cell lipo battery,10x6 graupner folding prop.I needed 9oz of nose ballast to balance at the cg(old wheel weight worked) because cutting the steel from the nose and putting the motor on wasn't enough weight. The motor combo pulls well but the 3 chanels set up lacks a little in rudder authority. I found this when I got a crosswind landing once and I couldn't compensate with enough rudder. It did a wing-tip to tip walk.I fixed the wing bolt area of the fuse and have flown it since.I've managed some max flights as it will thermal, about 35min flights on good days.I belive any of the .15/.20 conversion combos(electric to glow) from e flight or tower will work fine. Just match current draw with esc/bat/motor and prop used.Mine is pollimg aproximately 240watts.
I'll try to include photo of finished Bird.
Don
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Old 12-22-2007, 12:30 PM
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kcspangler
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Default RE: dynaflite bird of time

Hi,

I am just in the midst of completing this myself on a BOT ARF. I did a tone of research and questions across many forums. As soon as my digital camera charges up I will send you pictures and a description of what I did. God knows I could have used as well.

Please stay tuned, could be a few days with Christmas around the corner, but I will get back to you...Merry Christmas
Old 12-22-2007, 12:48 PM
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G_eronimo
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Default RE: dynaflite bird of time

ORIGINAL: Sailplane
...
I'm also planning to purchase a BOT (ARF) and converting it to an electric. It looks like yours has a balsa fuse; I believe that those that are being sold now have fiberglass fuses with lead weights in their front ends.
...
Ernie (AKA Sailplane)
Hi Ernie,

the 2 versions of the BoT are very different, just the shape is the same. I think, the design ot the kit is more than 30 years old (but still sold):

The ARF has a fiberglass fuselage, i believe (not some type of plastik). The wings are divided into a centerpiece and the 2 outer wings. The ARFs are known to like to fold their wings on a winch, if not made stronger. I have seen one from a club member, which fell apart after wing folding. The winch was operated as smooth as possible. No F3B-start.

The kit, which I buildt, is for "woodworms", all balsa. The wing is divided at the center. The outer parts are not removable. But it should be easy to do so.
The spar is reinforced with carbonfiber on top and bottom.

I will take some fotos now and post them with some more explanations.

Uli
Old 12-22-2007, 02:13 PM
  #9  
mrkite
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Default RE: dynaflite bird of time

Here is the 1st Elec Brid of Times back in 77 or 78 It had a OLD Astro 15 can motor in it
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Old 12-22-2007, 02:44 PM
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G_eronimo
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Default RE: dynaflite bird of time

ORIGINAL: Sailplane
...
G-eronimo, can you give us more details on your brand of motor, reduc gear (if any), motor size, brand of ESC and Rx, how you installed the three servos (1 elevator & 2 spoilers), brand of spoilers, and anyother ideas that you came up with in your modification. Also, could you have placed a single spoiler centered over the fuse? What was the total all-up weight. Gees man..., how in the world did you fit all of the above, plus a 4S LiPo, in that tight space.

One last question: Can it thermal?
...
Ernie (AKA Sailplane)
I just took some photos.
The main task during conversion was, to use existing equipment. So with some more modifications and smaller LiPos and a smaller (size) brushless the weight would drop.

Motor is a Keller 40/10 brushed, which lay around (high quality brushed motors are cheap now on ebay as everybody goes brushless). Unfortunately it needs 10-16 cells (Ni) and I usually fly 8 - 10 cells (2000-2200 mAh, GP or Sanyo). There wasn't even enough space to fit them. Maybe 16 cells 2/3 size will fit, but I don't have them. So I decided to use 4 LiPos 3600 mAh, which were left from another project. Schulze esc (50A or more ?) with extra LiPo-protection circuit (different low-Voltage cutt-off). 12 x 8 folding prop. Motocalc gave me a good rate of climb (3.5 m/s) with that combination at moderate 23Amps. Elevator servo is up front, standard size. Rudder-servo is in front of the tailfeathers, HS-81 MG. The 2 spoiler-servos (HS-81 or similar) are inside in each wing near the spoilers.
I am using a Futaba 2.4 GHz system with a 6- or 7-channel receiver and my Hitec Eclipse 7 with a Futaba 2.4 GHz-module. Works fine.

The fuselage (and the wings) was already build when I decided to convert it to electric. So it did not fit batteries up front. Maybe shorter LiPos (which I don't have right now) will fit, but then I have to move the elevator servo. I had to put in a piece of metal up front to get the right CoG. I think the plane weighs now as much as with NiMh-cells of the same voltage.
I also added the wooden sticks for the rubberbands to hold the wings OUTSIDE of the fuselage. The other ones inside are still there, but I think it is safer with my version with a little aerodynamic penalty.
I added some holes for cooling. 2 in the "motor-compartment" and 2 in the "battery-compartment".
Because the propeller was scraping on the ground at landing (the plane literally landed on the propellerblade[]), I added some plywood at the bottom of the fuselage for propeller clearance. It doesn't look nice and might add some aerodynamic penalty, but it works. I used the mounts from the tow-hook. Unfortunately you don't know where the propeller stops, but with Murphy's law it will always stop with one blade at the bottom.

I don't know the brand of the spoilers, as I bought them at ebay.
I wouldn't use a center spoiler. The turbulence might affect the single rudder (no aileron here to compensate[X(]).
I am still looking for the information about spoilers. I will post it here, when I find it.

There wasn't much thermal, when I made the testflights. But it glides very well. With the higher weight, then the pure glider, it penetrates better in windy conditions. Landing is very easy with the spoilers.
The next flights will be with a Vario (picolario), if I find enough space inside the fuselage.

Uli
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Old 12-22-2007, 02:47 PM
  #11  
G_eronimo
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Default RE: dynaflite bird of time


ORIGINAL: mrkite

Here is the 1st Elec Brid of Times back in 77 or 78 It had a OLD Astro 15 can motor in it
WOW!

Look at that radio.[sm=eek.gif]

Nice plane!

Uli
Old 12-23-2007, 10:25 AM
  #12  
Sailplane
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Default RE: dynaflite bird of time

My thanks to mkpalmiero, G eronimo, avroarow, kcspanagler and mrkite. I can't believe the tons of information that you guys gave me in just one day. This has been very helpful to me.

Ernie
<Sailplane>
Old 12-24-2007, 10:18 AM
  #13  
kcspangler
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Default RE: dynaflite bird of time

OK,

Here are some quick pictures of what I have done with spoiler installation on my BOT ARF. This should also answer other questions on this forum in terms of what is under the skin since I stripped everything away (including the tail) to recover with some transparent covering (better for in thermals).

My plan is to install straws to route the wiring from the servo to the inner wing. Also, many have been adding carbon fiber to the wing, however I have successfully winch launch this bird many times...so I plan to merely wrap some fiber glass cloth neatly around the center section.

I will send final photos of the working spoilers as I believe the connection to the spoiler blade and servo is the most crucial and determines the final design, again something I found hard to find...although simple in concept. I have added small magnets embedded in the spoiler frame to help suck down and the spoiler since I have designed some slack in the servo linkage. This ensures no load on the servo when the spoiler closes. The magnets can be sourced through Hobby Lobby and are meant for canopy hold down solutions. The hold down power is excellent, but still not enough to keep the HT 51 servos for pushing open the spoiler.

For final testing, I will also record a video of the spoilers working and the radio setup I will use on my JR 8103 to actuate and mix in elevator.

Please stay tuned.

Cheers, and Merry Christmas to my fellow hobbyist out there!!!
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Old 12-24-2007, 11:54 AM
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mkpalmiero
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Default RE: dynaflite bird of time

Nice job kcspangler, it looks like everything is going well on the spoiler installation.
NICE JOB of stripping the covering, you have more patience then I do.
Old 12-24-2007, 02:26 PM
  #15  
Sailplane
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Default RE: dynaflite bird of time

kcspangler,

Great job on the spoilers. What are you using for hinges?

To all, Merry Christmas/happy holidays,

Ernie
'Sailplane'
Old 12-24-2007, 02:33 PM
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kcspangler
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Default RE: dynaflite bird of time

Hi All,

I am using 3M hinge tape from the hobby store. I have used this for 10 years...excellent, no give, very flexible and hods excellent, even on my faster slope planes. put a little talcum powder on the exposed edge of the tape and it makes for excellent gap seal too.

Cheers,
kcspangler
Old 02-02-2008, 10:36 PM
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Ted B
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Default RE: dynaflite bird of time

I built a bird of time last year for aero tow but went with flaps instead of spoilers I took out the polyhiedral joint making the wing straight at that point. The wing is two piece. It was easy to do just making the inboard straight. section the flap length.I have only 3 flights on it with the only problem being on the tow portion, we think the tow tugs are too fast for the model, Will experiment more this season
Old 07-11-2020, 06:35 PM
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Stubby01
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What length of spoilers recommended for the BOT? I bought some 440mm but I think they are too long . Thoughts?
Old 07-12-2020, 06:47 AM
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speedracerntrixie
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Yes that does sound a bit large. Typically both spoilers added together should be approximately 25% of the wing span. In the case of a BOT with 3M span spoilers would be 325mm each. You would also want them placed outside so the turbulent air does not hit the stab. Sometimes that is a bit difficult.

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