Bird Of Time 3 Meter

[eightwgt]

I saw the 'Bird Of Time' kit today at my LHS and was wondering if anyone had comments about it...... I really came close to buying it but thought Id ask opinions on here.....


Thanks

[Thermalin]

I have never flown one but others really seem to love it.. there are some BoT comments in the nostalgic fever thread (http://www.rcgroups.com/forums/showthread.php?t=150339)... Search on bird of time and you will find quite a few posts. Searching on BoT will get you "Bot"h "Bot"tom, etc. and some good hits as well.

here's a good one!
http://www.rcgroups.com/forums/showthread.php?t=150339&page=6&pp=15

Mike

[Ollie]

BOT is a very design. Kit is poor wood. Kit changed the design to make the price lower. The BOT ARF is worse!

If you like the looks and the kit quality see Big Bird XL or SKY BIRD:
http://www.skybench.com/

[eightwgt]

Ollie

I read (after posting) some reviews about the ARF BOT... most good except old post about the wing. There has since been a tech paper posted on GP's site, and improvements to the wing. I saw some user posts that love it.

For the ARF- 125 dollars VS the kit - Im going with the Arf.... its not like I cant tweak it a little - which I plan on removing the center wing covering, beefin it up and adding flaps........

[Ollie]

The low price is quickly enjoyed but the poor quality structure is painful under the covering for a long, long time.

[eightwgt]

Gee Ollie.......

Are you tryin to make me regret buyin this plane ? Im gettin worried now since I put it on layaway....... I hope I didnt make a bad purchase - I really like the BOT and allways wanted one.....

[Ollie]

If the RTF BOT is carefully flown and landed it will be OK. If the BOT is over speed flying, over launched or dork landing you will break it much, more than will high quality planes.

The word Yugo comes to mind.

[eightwgt]

Ollie

Do you have one or someone you fly with have one ? You talk like you have personally witnessed the problems so I am very curious.... You got me thinking to perhaps forget this model all together.......

[sierra-gold]

Ollie
There has since been a tech paper posted on GP's site, and improvements to the wing. I saw some user posts that love it.


The BOT ARF is made by Dynaflite... not GP. The Tech Note I saw didn't mention any wing improvements, it just suggested to use a high-start and not a winch. That was their immediate "response" to destroyed wings during launch.

That said, I have a BOT ARF that I intend to convert to EP. I'm hoping that will take most of the launching stresses off the wing and make it a fun sport flyer.

SG

[solo6796]

With the kit and a few mods, you will have a much lighter and stronger ship than with the ARF. Mine will take hard launches and a nice zoom at the top.

http://www.rcgroups.com/forums/showthread.php?t=269207

AJ

[John Gallagher]

AJ,
If you've gone that far to modify the BOT, why not go with a pod and boom fuse.

[R. Carver]

Ollie

I read (after posting) some reviews about the ARF BOT... most good except old post about the wing. There has since been a tech paper posted on GP's site, and improvements to the wing. I saw some user posts that love it.

For the ARF- 125 dollars VS the kit - Im going with the Arf.... its not like I cant tweak it a little - which I plan on removing the center wing covering, beefin it up and adding flaps........

I've seen a couple folded wings on a LIGHT winch launch. Also, one of the guys at the club bought one and stripped the covering and beefed up the wing. IMHO, it would probably be easier to build the kit right to start with.

[eightwgt]

How long ago did you see the folded wing episodes ? I had someone Email me today that told me the plane was stronger now than people were saying so I am getting conflicting reports.....

I also read a review about it and the writer said he had winched it 20 times or so with no apperant problems.....and it was the same ARF Im looking at.

Id love to build one but right now I dont have the dedicated space required to build a kit from scratch ..... geee..... and I WAS excited about this plane....

[solo6796]

I wouldn't buy the ARF... Unless I just used a hi start.

John,

My next project IS a pod and boom..... But with better wings. I just HAD to have a BoT looking stock... (but it's not!)

http://www.rcgroups.com/forums/showthread.php?t=334018


AJ

[schrederman]

Here in Houston, we've seen every one that came out of the box destroyed by extremely weak wings, and that's probably a dozen of them. I know it's disappointing to see something that looks that good and find out it's that bad. Look at this way - you're learning this lesson the EASY way - at someone else's expense. Ollie's not trying to pop your bubble, just trying to protect your hobby time and dollars. He's right on the money.

Jack Womack

[eightwgt]

Ok thats it.........

Im going back to my LHS and telling them I dont want it and printing this thread to show them why......

Im going to build a Supra and or a Bubble Dancer anyway...... so I dont need the BOT... (just wanted one )

[Thermalin]

Is it because the wings are rather thin... and inherently weak.. or just poor quality...Mike

[sierra-gold]

There are probably a number of things wrong with the BOT ARF.

The major thing is that the shear webs between the top and bottom spars of the wing are installed with the grain running horizontal. It should be vertical to provide shear strength. The joiner boxes also appear to be weak, based on reported wing breaks.

SG

[Ollie]

The BOT ARF wing design is very poor strength! BOT ARF is poor compared to the original design of the BOT.

For value and quality get best design and wood:
http://www.soaringspecialties.com/birdoftimeglassfuselage.shtml
BOT
or
http://www.skybench.com/
BIG BIRD XL RES 110" WS
SKY BIRD RES 132" WS
or
RCM plans service. Plan # 751
http://www.rcmmagazine.com/e/env/0001sAhUmd9sBP4gDI7n753/store/store-plans.html?command=env

[solo6796]

Hey, Jack,

I sent ya a pic of our 126" er, but it got bounced. Please PM me your new e-mail...

AJ

[southern soarer uk]

Buy it! these bird`s are great you can strengthen the spars on the top and bottom with unidirectional carbon but build in spoilers or you will never get it down, it glides forever and everyone loves the look of a BOT in the summer sky.

[eightwgt]

SOUTHERN

That easy for you to say - looks like you built a kit !!! I may go ahead - who knows.....

[solo6796]

Here's something my friend Ed said on another thread now running, and I agree totally.......

Thermalin:

The original BoT was designed in 1970's and today's winch performance was not something the plane was expected to handle. The design is quite serviceable if launched within the bounds of its design philosophy. It is a spectacular design in the air and a very good flyer. Most of the planes designed in that same era are in a similar situation regarding strength of the design.

Dynaflite has chosen to use the cheapest balsa available to put in the kit. This means the balsa will be hard and heavy. If you build this plane with the materials in the kit and to the plans, you will wind up with a heavy Bird of Time that will fly well in spite of the weight. The Dynaflite Bird of Time kit sells at Tower for $65. In comparison the Spirit 100 kit sells for $95 and 3 meter Gnome from Midway sells for $120. What this means is that you are not going to get top quality material in the Dynaflite BoT kit. I am not speculating. I built one from the kit myself. If you buy one of the kits, I think you are going to want to change some of the balsa for better grade, lighter stuff.

The BoT ARF was completely redesigned and having been designed in the era of todays high strength winches, the wing structure is severely weak. There is no good excuse for Dynaflite to have underdesigned the ARF like they did. It was a great disservice to the design. I flew mine off of a high start. The workmanship of the ARF was quite good, but it was designed by the cost accountant, who must not be a sailplane flyer. If you fly off a high start, you will possibly be alright, but mine failed when I was trying to get down out of a strong themal in Feb. 04. It weighed about 63 oz. and flew beautifully. The kit version weighs in at 55 oz. and could be built lighter with judicious wood selection. You can find my build thread posted here and the build thread by Alan Jones posted here as well. Alan used CF on the wings. We both used a 3 piece, bolt on wing instead of the kit (and original) 2 piece rubber-band-on wings. I believe there is some info on a BoT that was built by Jack Womack buried in the Houston Hawk build thread.

Overall, I think you would be better off, buying the kit and some decent wood and some CF and building the plane.

Regardless off the problems with the Dynaflite offerings, I will always have a BoT in my hanger.

EJ

[solo6796]

Mine came in at 56 oz. and takes a heavy footed launch... Looks GREAT in the air. Had to have a BoT in the hangar!

AJ

[eightwgt]

Those are PRETTY BIRDS !!!!


OK GUYS........ I am going to clear this up for everyone once and for all... Im takin one for the good of us all. Im picking up my ARF BOD tomorrow from the LHS , and removing the covering on the bottom middle section and figuring out how to beef it up- Ill post before and after pictures etc....

We can start a "BOT ARF modification" thread and then everyone - including myself will know beond a doubt what they are getting into !

What do you guys think ??? Am I nuts ?

[Kwok_Yu]

Well, I too am think of getting the BOT arf and adding a electric motor to it for launching. So go for it.

Question for those with a BOT. Is there room for a 3S lipo battery pack? I am most concerned with the height. I need 60mm (2.4") tall x 95mm (3.8") long. Width should be no problem being less than an inch. Thanks.

-Kwok

[Badger]

Built from a kit, mine weighs under 39 ounces, and will take the most brutal launch on the winch. All wood parts on my plane used the supplied balsa and plywood, on a reinforced plane the wood is the appropriate strength.

Faced with the same decision that you have, it is easier to build the strengthened wing than to retrofit the ARF.

[John Gallagher]

Those are PRETTY BIRDS !!!!
We can start a "BOT ARF modification" thread and then everyone - including myself will know beond a doubt what they are getting into !
What do you guys think ??? Am I nuts ?

About a year ago someone else did that thread.

An electric version is a good idea. A lot less stress on the wings. See the recent threads either here or in the Electric sailplanes forum.

Badger,
Nice pod and boom BOT. No wonder it's only 39 ounces.

[eightwgt]

BADGER

I agree but... at present I do not have room to build a balsa build up from scratch - so I put it on layaway before I knew about the wing problem.

So now Ill open it up and get everyones ideas and fix her up - yes a pain... but perhaps all for the better..... Ill have a BOT, and everyone can see at last how the spar is built because Im going to show everyone !

Tom

[solo6796]

I did that.... With a BoT 3000. Dang joiner broke, and totaled the plane. You will spend as much in time and material as building a better one, and the room will be just as messy for a while....

AJ

[eightwgt]

AJ

It cannot be that hard to add some strength to it. I have had emails from guys that HAVE winched it (light) and had no problems... so I look at it like its a plane that your rolling the dice with IF you dont fix it.... so I will do just that.

Ill have it fixed up quick ..... If I can put a 2 meter back together that was in 7-8 pieces (large) this will be a breeze !! (famous last words) I plan on fun flyin with it and will remember its limitations and therefore enjoy it.....

plus Im startin work on a DLG wing mold - actually firin up the CNC tonight to try a test mold... then its time for a SUPRA =)

[sierra-gold]

BADGER

I agree but... at present I do not have room to build a balsa build up from scratch - so I put it on layaway before I knew about the wing problem.

So now Ill open it up and get everyones ideas and fix her up - yes a pain... but perhaps all for the better..... Ill have a BOT, and everyone can see at last how the spar is built because Im going to show everyone !

Tom

Please do the BOT ARF mod thread. I purchased one over 1 year ago from a guy who does magazine reviews and did one on the BOT ARF. I got a good price on the completed BOT, with servos, plus an extra wing center section that has spoilers installed. However, he did no strength mods while adding the spoilers. :(

I plan to convert it to EP, but I may do surgery and "beef" things up for extra insurance.

It has been sitting in the box in my shop and I think this thread and the upcoming mod thread will get me going on the project.

SG

[Thermalin]

I agree with what was said earlier regarding using a design for what it was not intended for... I woiuldn't take an RV four wheeling either... But the thing sure is pretty... will have one someday for sure.

Bader... why the extended rudder? better response?
Mike

[ejett]

eightwgt:

If you really want to get bitten by the bug to build or own a Bird of Time, then go here:

http://isoar.ca/~andrewm/rc/bot/

My plane is the last one in the list.

EJ

[sierra-gold]

OK, I went and pulled the BOT out of it's shipping box. I started "emptying" the fuse. I'm going to convert to EP. Yikes, an HS 625 MG servo for the rudder.
:rolleyes:

And then I saw it... the biggest ocean surf fishing weight I've ever used. :)

To those who have an ARF BOT - was the chunk of lead factory installed in the nose?

To those who may have converted to EP, any tricks to removing the lead? It looks like if I cut the nose off at the back of the lead it may be a larger firewall than I want. :confused:

This is going to be a fun project!

To the person asking about room in the nose for a LiPo pack - it looks to me like if you move the rudder servo back under the wing and remove the lite-ply servo deck under the canopy, you could run a 3S2P TP2100 pack... which is my plan.

SG

[ejett]

I saw someone post that you can enlarge the small hole in the nose to something larger and poke a rod or small (say 1/4") iron pipe in there and bump it smartly with a hammer and the factory weight will drop right out into the canopy area. Then you can cut it back to the point you want to for your firewall/motor mount.

EJ

[sierra-gold]

I saw someone post that you can enlarge the small hole in the nose to something larger and poke a rod or small (say 1/4") iron pipe in there and bump it smartly with a hammer and the factory weight will drop right out into the canopy area. Then you can cut it back to the point you want to for your firewall/motor mount.

EJ

Thanks EJ, that sounds like a decent plan of attack.

SG

[sierra-gold]

Just an update on the removal of the lead chunk from the ARF BOT fuse nose in order to do an EP conversion.

Basically I did as EJ suggested. I enlarged the small hole in the fuse nose - first I drilled it out to about 1/4", and that reveled a dead space in front of the lead. So I took a razor saw and cut the tip off the nose giving me about a 1/2" in diameter working area.

I had my son hold the fuse on the work bench and used a large screwdriver and a hammer to knock the lead loose into the fuse. It took several hard "taps" and a little verbal persuasion. :)

That piece of lead weighs 8.7 oz. !! My Motor/GB/folder only weighs 6.5 oz. That gives me 2 oz. towards my LiPo battery pack.

Once loose, it can be removed through the canopy opening.

Thanks again EJ.

SG

[Kwok_Yu]

Hello all,

I have taken the plunge. BOT arf is on sale for Tower Hobbies' saver club members. So ordered one yesterday. With additional coupons and free shipping, it was a really good deal.

Sierra,
What motor are you using? I only plan on using the motor for launch, so I am only going to run at 100 watts. Just ordered a Himaxx 2812-650 outrunner (2 ounces) and phx25 speed controller. Should have about 20 ounces of thrust with a 12x8 prop. Think this should be ok. If not, I have other uses for the motor. Also order a polyquest 3s 2700mAhr lipo for $50 (~6 ounces). So I expect to be a few ounces heavier than stock. But still hard to believe this is possible.


-Kwok

[sierra-gold]

My current plans are to use an AF 020 geared 4.4:1 with a 12x8 prop. I have these components available on my workbench.

However, MotoCalc tells me if I end up at 66 oz. AUW I will only get about 600 ft./min climb rate on launch. I know from my other gliders that anything less than about 750 ft./min. just seems too slow on launch. Personal judgement. :)

It looks like a HiMax 2825-3600 with a 4.3 GB will get the job done better. With a 12x6 folder it will climb out at about 875 ft./min.

Both of these options assume a 3S2P 4200 LiPo pack.

Kwok - I'm not sure you are looking at enough motor. I fly my Slow Stick on more thrust than 20 oz. and it only weighs 26 oz. How much do you expect your BOT to weigh?

SG

[Tim Jonas]

post pics when you get some.

[eightwgt]

Im picking up my BOT in the morning (Saturday)

Ill open it up and have lots of pics on here by mid afternoon.......

[Kwok_Yu]

Kwok - I'm not sure you are looking at enough motor. I fly my Slow Stick on more thrust than 20 oz. and it only weighs 26 oz. How much do you expect your BOT to weigh?

SG
I might have to rethink the motor. Will decide what to do, when I see the motor and glider in person. The BOT is probably alot bigger than I can imagine. I am getting only a third of your climb rate when I input 60 ounces empty weight.

I have been flying an goldberg electra for over 10 years and everything is still original. Only fly it about once a month during flying season and expect the same for the Bot. It's got less power and weighs close to 3 lbs. It climbs slow, but ok for me. I expect the BOT to be 4 lbs, but that's also what it would weight as pure glider. Thinking it should perform better than my electra, with my intended setup. Just have to see what happens.

-Kwok

[Ollie]

In fact, by varying the size of the spar to match the load, you will end up with a spar that will carry the intended load and has a much better strength to weight ratio than a spar with a uniform size along the span. Better yet, the mass of the spar near the wing tips will be less than a uniform spar and that will result in better handling qualities in flight.

The strength and stiffness of the spar depend on the vertical depth of the spar as well as the crossectional area and material strenght of the spar caps and the crossectional area and material of the shear webs. The maximum bending load on the wing is determined by the maximum tension on the tow line or the the maximum inertial (G) load of any maneuvers.

In the case of a cantilevered wing (unbraced by wires or struts) there is a lift (force) distribution. The shear forces are the first dirivative of the lift distribution. The bending forces are the second derivitive of the lift distribution.

Fortunately, there are some conservative simplifications that can be made to avoid the use of calculus and will give a reasonable estimate of the strength needed along the spar's length.

If you give me the vertical spar depth and the estimated weight of the model, I will run through the the details of the calculations and explaining the simplifying assumptions in my reply.


*

[mdennis]

sierra-gold,
We passed paths in a couple of other threads about this. I electrified a BOT last year and used an Aveox 27/26/1.5 with a Kontronic 5.2:1 gearbox turning a 16x10 prop. I am using a Kokam 3s 2100mAh 20C battery. I pull 40A and get a measured climb rate around 2500 ft/min with 3 or 4 relights. I don't remember what motocalc said my static thrust would be.

I reinforced the spar, added spoilers, moved the rudder servo to under the wing, added cooling vents and put a spring loaded hatch latch on. It sounds worse than it really was. It's a great plane to spend a relaxing afternoon flying.

[bobby legue]

Hello all,
My son and I have been flying a 2X4 and a spirit select electric and want to get a two meter plane, what do you suggest? We have a BOT in the hanger but we are not ready to make that big of jump. I have flown for 10 years and he new at the game. I am hoping to take small steps as that is how I learned. So he too can have a wonderfull time. My Dad my brother and my two sons as well as my middle daughter all fly. But this is after a five year hiatus. When I look through the magazines every thing looks almost foriegn. Please help your help is sorely needed. Thanks

[ejett]

The Spirit select is a 2 meter plane. I suggest that you get a Skybench Big Bird (2.5m). The BoT is a fine flyer, but if you have an ARF, it will be easy to break. But it is easy to fly as well.

EJ