Bird of Time-Millenium edition

[BMatthews]

This is a copy of something I started at another site as well as here but as I see lots of different people at both of them I thought I'd start this here as well.....

I've seen a few threads here reffering to BoT's and it got me thinking on MY BoT and how nice it looks in the air. But wouldn't it be nice to re-invent it for the new Millenium?

So I'm thinking that it could be modified to use ailerons and flaps and go for a modern brand name airfoil.

I see it with flatter wings but still using a shallow version of poly-hedral.......... or....... Perhaps......... GULL WINGS????????

Hmmmmm..... nah, sorta runs counter to the current findings about dihedral and tight turns. Stick with regular dihedral.

So very shallow poly (probably about 1/2 what the original has), ailerons and flaps.

Airfoil. I'm thinking here that Mark Drela's AG35 off the Allegro-Lite would be a good choice as it's made to work with built up methods and "real" covering results. And I hear from all the reviews that it penetrates very well even at light wing loadings. The outer 12 to 14 inches of the tip panels would transition to the AG38 and have some washout built in to ease the tip loading and hopefully control the tip vortices somewhat.

And I'd probably also lengthen the tail moment slightly. I always found that my original design had a tendency to level itself out of a turn if I let the speed get a bit slow. I had the same problem with a 2 meter glider design called the RO-8. I thought it was just me until I made a second electric powered fuselage for the RO-8 wings and stab and lengthened the moment and reduced the fin area. What a difference. Very snappy turn entries and positive groove while turning at any speed.

All in all aside from the dihedral reduction the mods I'm thinking of wouldn't be visible unless the two models were side by side.

So whadda ya think? I know the outline runs counter to a lot of the latest Schumman tip design theories but it's such a pretty outline that it's gotta be worth an update. The original layout is certainly no slouch even today and I can only see this version being better.

[T. Lyttle]

... reinventing the wheel...

I saw the BoT at Belgium in '79, fighting it out with the Europeans, along with the SA Yellow Bird, the last (nearly) of the poly ships in WC competition. Either of these models was beyond the capabilities of most pilots as built. Usually, someone who is unhappy with a BoT has never pushed the model to its full capabilities, or stuck with the model to find out what it really can do. The only change I would make would be to the airfoil, using E193 if it doesn't have it already. I can only imagine the pride that Thornburg must feel, seeing the 25-year-old design still being campaigned with success.

The Yellow Bird is still in my mind: watching that model rip through the Speed course, rolling (on rudder!) inverted to make the turns was indeed a sight to see. :eek: As I have said before, modellers have the habit of trying What is New before they master the model they have!

[BMatthews]

I hear ya Terry, up to a point.

I like the positive NOW response that only ailerons can give. Too often I've had the wing of my Bird or RO-8 get levered away fromthe thermal while I'm holding full rudder to try to turn into it. The aileron models I've flown, on the other hand, almost look like they are pivoting off the down going wing as the model is forced into the thermal without having to S away and then back into it.

My existing Bird is actually not totally stock already. It was built using a Selig 4061 airfoil and has fully sheeted center panels to help support the reduced chord thanks to using flaps instead of spoilers. Also the wings plug onto the fuselage rather than plugging together and then mounting on the fuselage. This gave more room for the flap servo install in the center area.

And besides, I LIKE to do my own thing. I was just thinking that I'd use the BoT outlines to wrap around my own ideas since they looked so nice in the air. There's no doubt about it. The sky is a prettier place when there's a couple of BoT's up there.... :D

[jhogarth]

If you build this modified BOT let us know how it works out.
p.s. is this a 10 year old BOT with flaps?

[BMatthews]

Originally posted by jhogarth
If you build this modified BOT let us know how it works out.
p.s. is this a 10 year old BOT with flaps?

It might be......... :D

Yeah, it's Rick's old model with a few repairs and new covering. And welcome to the site.

[Ollie]

BMatthews,

I like your idea, posted elsewhere, of extending the BOT tail moment arm some and doing your own fuselage by the lost foam method. As you are probably aware it is sometimes hard to keep a long thin foam plug from bending when internal stress are relieved when the outer foam is cut away. Embedding a piece of 1/4 inch music wire in the center of the foam from the wing aft will keep it straight. Leaving a couple of inches of music wire projecting from the aft end of the foam plug will provide a convenient holding point when glassing the foam.

On the subject of dihedral, our thinking diverges. While ailerons can be made as effective as you want them to be in rolling the model, so can rudder in conjunction with dihedral/polyhedral . By concentrating dihedral in the outer wing panels and making the rudder large enough and with enough aspect ratio, you can get all the roll control authority that you want and then some. Now you may object to so much dihedral on aesthetic grounds or the yaw-roll coupling but, if you haven't been satisfied with its roll authority you just haven't used enough dihedral or its equivalent.

It's also true that a rudder-dihedral (yaw-roll) setup has to deal with the moment of inertia in both yaw and roll. Therefore the response is somewhat slower than the same plane with ailerons which only have to overcome roll inertia. This slight delay can be minimized by keeping the wing tip panels and tail as light as possible. It is also true that ailerons and associated servos increase the roll moment of inertia, partly offsetting their advantage compared to the rudder-dihedral combination.

A few of reasons besides style, that the BOT has been so successful are that it had less mass than typical in the wing tip panels, had a low wing loading and came with a thin airfoil for its day. The Bubble Dancer carries that a step farther with lower wing loading, thinner airfoil and even lighter extrimities. So much so that the 10 foot span Bubble Dancer has skied out repeatedly from hand launches. It has every bit the quick roll response necessary to be able to work lift that is only a few times bigger than its span.

[fledge]

i must agree with terry,i like the idea of the mods to the BOT but i really think that you would be moving backwards,not forward.

i have always wanted to make improvements on differant gliders that i have built but have resisited only because if i make to many changes,i might be dissapointed,,although thats just me!

i also understand what you mean about the glider not turning fast like an alieron glider but thats just the nature of the beast.

the poly wings may not respone to roll well but they are great at reading lift and also aid in preventing tip stalls

its very tempting to make a bunch of changes to try to update on old design but im sure your not going to really improve on it,it is what it is,,a great old thermal ship!!

i would be willing to bet that the mod on your original inboard panels may have given you a performance advantage but it may have also slowed down your roll rate


i would think that there is a bigger improvement to the kit buy just simply using some of the great materials around theses days to try to just lighten the wing load for a better sink rate

i just finished building an old sagitta 900 and i choose to build it stock with no mods other than CF on the spars,turns out that a friend of mine also built a sagitta but with foam wing cores

both sagittas have the stock poly etc but his handles stiffer and sluggish partly due to the smooth finish on the wings

my point is;if you make to many changes,you may have well started from scratch and build a glider of your own design then at least you could rename it;)

good luck on your project and i hope it works out but please dont call it a bird of time unless its at least 90% stock


fledge

[BMatthews]

Originally posted by fledge
............if you make to many changes,you may have well started from scratch and build a glider of your own design then at least you could rename it;).........

fledge

True.... true.....

Ollie and Fledge, you both have a lot of good points in what you say. Ollie, while I agree in principle with your statements about proper dihedral and rudder design versus the ailerons I can't help thinking that a proper dihedral design would look bloody awful if applied to the Bird. I honestly feel that the best poly setup is the latest 5 panel designs that are around these days. (Actually I suppose the "best" would be an elliptical arrangment all molded, but that's another topic) About 8 or 9 years ago I upgraded a HLG from 4 panel poly to a 5 panel wing. The new wing actually had less overall dihedral by measure but even so I got much better rudder response at slow speeds just because the dihedral components were out at the tips. Come to think of it there were only a couple of people, if any, that were using 5 panel wings at the time. Perhaps I was an innovator and didn't even know it...:D I got the HLG done and then went Old Timer flying since then. But, getting back to the Bird, I think it just doesn't allow for this arrangement without looking silly.

But as far as the poly and aileron controversy goes I still like the aileron option. The RO-8 is a poly ship with fairly high angles. It's also built up as lightly as a radio control glider can be with only 1/8x1/4 spruce spars and just ribs and small strips for the rest of the structure. It just doesn't get much lighter than this and still survive a winch launch. On the electric version it has the longer fuselage. For a rudder/elevator design the electric has one of the fastest responses of any of this type I've ever flown...... but it still can't hold a candle to the aileron types I've flown when you want it to turn NOW. Perhaps there is room for improvement in the poly setup but it's just easier to get the response out of the aileron designs. And then there's the loss of performance question in the poly vs flat'ish wings.... but that's another topic.

Oh, and Fledge. Getting back to the "at least you can give it your own name". This RO-8 was from a kit that was SO badly die crushed and had such bad wood that I tossed over 90% of the kit. I used a different airfoil, modified the fuselage construction, modified the stab airfoil, construction and mounting method, etc. When I did an audit after it was all done I had modified everything. The only things I used from the kit were the plan outlines and the trailing edge balsa stock..... and then I changed the fuselage design for the electric model. I doubt if Rick Odle would even recognise it. I don't care though. It's what I like to do. As you can well imagine I don't buy many kits and I usually hate myself in the morning when I do break down and buy one :D So in the end the name thing may just sway the decision.

Fledge-That bit about poly models controlling tip stalls and reading lift better isn't really true I believe. I think this is where you're trying to compare a bad example of one type to a good example of another. I had a 2 meter Hack that I built to try ailerons. Here again it was built very light so it would build quick and it signalled lift very well. Tips stalls were easily avoided as long as I didn't input large aileron commands at slow speeds. Other models DO have issues, I've flown enough other peoples' designs to know that it's much easier to design a bad aileron model than a bad poly model. The poly seems to cover up errors better. I urge you not to give up on the flat wings until you try a number of them.

I sorta doubt that I'll ever do this anyway. I hate walking down old roads and I do like designing my own. It's certainly brought up some interesting conversation though. And perhaps it'll spark some minor upgrades for the next person to build one of these fine models. The longer tail moment, to my way of thinking, would make this good design into a great design at very little cost in other areas.

Ah, so many projects and so little time. If only I could find a pill that eliminates the need to sleep....

[T. Lyttle]

Individual thinking and modification are the cornerstones of modelling, and I am just as guilty. My Oly II had very little to do with the plan, other than basic outlines and moments. However, it did NOT fly to my satisfaction as designed; various "arrivals" allowed me to justify changes!

By the time I was finished, the model would stall a tip as it brushed by a thermal, diving into it... on its own. Trimming allowed me to complete a flight with minimal input to the radio, even S-turn launches in light wind could be trimmed in. Did it mean a lot of experimentation with incidence/noseweight/angle of attack/trim adjustment? You already know the answer.

A good model can always be a great model. Change is no substitute for knowing your model well enough to realise what changes are required. If th BoT isn't doing what you want, have another look; I saw the model in World competition, and it was great, ailerons or not...

[fledge]

there is an artical on skybench site that has a bird very similiar to the BOT with flaps etc that might interest the original starter of this thread check it out, its got a differant airfoil,differant tail,same trailing edge though,,ah a time less design

fledge

[BatteryJockey]

Hello Fellow BoT Fans,

I just finished my second BoT that I modified to to the following specs. I strechted the wingspan to 144" and the fuselage to 58" from nose to back of rudder. I added ailerons to the outer wing panels, and Gruapner pop up spoilers to the inner panels. I customized the fuselage to accept plug in wings and and all of the hardware to make it an electric. The plane came out weighing 78 ounces with a 10 cell battery pack, this gives the plane a 7.8 ounce wing loading. I,m using an AXI 2820/10 Brushless on 10 cell throwing a 12" x 6" Graupner CAM folding prop that will give me 48 ounces of thrust. I the weather is good she will get her maiden flight in this sunday. Right now its a miserable 62 degrees here in Miami. Sorry, I just saw the news about the weather up north and had to say that.

Thanks for Listening,
Batteryjockey

[BMatthews]

Originally posted by BatteryJockey
Hello Fellow BoT Fans,

......... Right now its a miserable 62 degrees here in Miami. ...... Batteryjockey

PHFFTTHH ! ! ! ! ! ! ! ! to you and yer 65 degrees........ :D

Let us know how it goes. AND DON'T COME BACK WITHOUT PICS!!!

[BatteryJockey]

BMatthew,

It flew beutifuly, 2 short flights to trim out and then one great flight. Climbed out at 45 degress and then just parked with it's nose in the wind. This plane is truley a floater. It took me 5 minutes of circling just to get it down from 150 feet. The spoilers got it right down once I got it to 15 feet. I should have pictures to post on saturday.

Gilbert

[Rifleman]

Still looking for advice on a bash from RES to FEAR ?....I did one to a Sagitta 900 and the difference was fantastic......I have a fus done and am still waiting to decide on my wing config....it will be a four servo wing, no doubt, but I'm not sure whether or not I'll stay with 25% chord AIL&FLAP....I may go to 30%....only for the idea that if you move a small chord surface into the airflow you generate more drag than a large surface moving less into the airflow, for the same control effect......on my previous model, I reversed the outer poly braces and kept that part of the wing flat, and only tipped up the final rib bay by doubling up that last rib(the one before the tip rib) and inserting a piece of the trailing edge stock I saved by building up my flaps and ails....this canted up tip made this thing groove like it was on rails in a thermal and it never really mattered how tight my circle was either.....I never mixed rudder/ail and found if you fly the rudder all the time, you will always be able to stay on top of the circle.....a constant mix of that type(rud/ail) won't cut it if you fly the rudder correctly, as you know, when flying through and coming off a turn you are essentially crossed up a certain degree due to circling with the rudder and flattening the wings to present more area to the thermal........ the biggest benefit you will see is the ability to change camber as you deem necessary when moving in, or travelling to the next thermal.....
Keep the wings true by sheeting if need be, and seal all surface gaps to enhance controllability.........
My flying weight for my bashed 900 was 58 oz and that included two JR 321 double ball bearing servos in the fus for R and E and four JR 341's in the wing for F and A......battery was 800mah and rcv'r was JR 549.......Ballast of 24 oz was allowed for.......

[schrederman]

I had a Larry Jolly Pantera in the 80's that I flattened and then added ailerons. It had only enough poly to keep the top spar cap flat with a slight upward bend in the bottom spar. It flew nicely, but was a bear to set up without a computer radio. I was flying full-scale at the time so it didn't get my full attention. It was my first aileron ship, and I didn't build anything else until my Windfree in 2000, just after moving to Houston. I currently build and fly Legionairs and have a Fazer for my full-house duties. I am about to build a built-up, full-house ship to keep the weight down. It will be kind of a hybrid aileron / poly ship, and should fly sometime in June...:D

Jack Womack

[hyoung]

Hello all
Just starting to build BOT and could use some advice on installing
spoilers. This is where I am on the left wing. I will try to attach pic. any suggestions appreciated. hy

[hyoung]

Wasn't able to post pic even thou I reduced file size any way I have the left wing built to the point that I am ready to sheet the top of the D tube and join the inboard and out board panels. I am trying to determin where to locate the spoilers and what dimensions. ect. hy

[BMatthews]

The size for these isn't super critical.

If it was me I'd make them hinge off the rear of the spar or from a pre-prepared hinge bar about 1/4 wide or so that glues up to the spar and rear of the sheeting... depending on how you want to do it.

For size I'd go for 1 1/4 wide by about 9 to 10 inches long. Just pick the length so it fits nicely between the ribs that are closest to that number. If it ends up being 12 no big deal.

Started the fuselage yet? If not then I highly recomend stretching the tail by 1 to 1 1/2 inches. It'll make your thermal turns at low speed much groovier. Mine tends to straighten up and leave thermals if it gets too slow. Thanks to another model doing this and fixing it when I made an electric fuselage that was longer I'm sure the BoT would work just that little bit better with this mod. If you're worried about nose weight make the nose 1/2 inch longer as well so the moment arm is longer. You won't even notice the difference in looks. But the flying will have a cherry on the cake with this mod instead of just cake. Both good but the first is just that tiny bit better.

For the pics try using a higher compression JPG save. If the program you are using doens't allow that then resample the pic using a lower dpi count. That will give you the same size pic with a smaller file size.

But for this site you're only allowed a pic that's 700x700 pixels regardless of dpi. So reducing the dpi will keep the pic large but a little fuzzy.

Or at least that's my story and I'm sticking to it.... :D

[hyoung]

Thanks Matthews how would just outside of the sheeted area near the wing root work? I will try pic again . Havent started fuse yet will consider the extension.

[hyoung]

Out Board panel

[BatteryJockey]

HY,

Hoobie Lobby sells several kinds of spoilers made by graupner. on my first electric bot that was the standard sizeI used the thin hinged ones. On my new one that has a 144" wing span I am using the "Teck" spoilers for 5M sailplanes and they are very effective in getting the plane down when it just wants to float. Both types were operated by a servo in the fuselage..

Hope this helps,
Gilbert

[BatteryJockey]

Let me try to post a picture again.

[hyoung]

Good looking Bird Gilbert. Thanks, I will go with the hinged
spoilers. I will try my hand at making them and if they don't look good will order the Graupner set.

[BMatthews]

If it was me....

Looking at Gilbert's pic I'd go from the first unsheeted rib (looks like #4) out for 4 bays and make them 1 1/4 wide.

But you know.....

If you're doing this for contest work other than the RES class it would be worth using full span flaps on the inner panel. That's what my Bird uses and it works like a hot dang. If you go that route then I'd recomend sheeting the center panels to restore the torsional stiffness that you loose buy cutting down the chord.

If you want to go this route I'll measure my flaps for you. For sport flying though this is overkill. The spoilers will be fine for killing that long float on landing and don't get caught in the grass like the flaps.

[BMatthews]

Oops...

Sorry hyoung, I got so caught up in the color of Gilbert's Bird I didn't look at your framing shots.... :D

From the sheeting out for 4 ribs should be super. A 5 rib span would be more effective but it may get into problems with the spar flex interferring with the hinge line. The surface will flex with the spar when it retracted but when it extends the width makes it very rigid and could stress the hinges. If you want to use 5 bays then consider splitting the spoiler into 2 parts. Even with a 4 bay spoiler you may notice the Monokote hinges getting a bit frayed at the ends after a while. That's from this same problem. They can still be right beside each other but the small 1/64 gap will allow some give.

[hyoung]

The (A) ribs out from the sheeted section are on 3 in. centers so going four bays would give me a 12 in. spoiler. I am inclined to just go with spoilers for this plane. BMattwews I believe you mentioned beefing up the upper spar in another thread would you do this with carbon fiber? hy

[BMatthews]

Yes, you want the carbon fiber strip that's something like 10 thou (.010) thick by 1/2 inch wide. On the center panels I'd glue it with Epoxy to 1/8 x 1/2 spruce for a very solid backing. On the tips I'd use hard balsa starting with 1/8 x 1/2 at the root and tapering as per the plan to 1/8 x 1/4 or so. Carbon the whole way out.

Ideally you want full width vertical grain webs between the spars for the first few bays to about 1/2 the way out to the poly break. Use 1/2 inch sheet for the first half of the inner panel then 3/8 for the second half. In the tips use 3/8 for the first two then 1/4 out half way and then 1/8 for the rest. I know that cutting and fitting these is a pain but it really is the best way. If you promise not to lead foot it you can get away with front and back webs. In this case use 1/32 ply for the whole center panel front and back. Same again for the first two outer panel bays and then 1/16 hard balsa for the rest out to the tip.

It's also best if the spars are positioned so they are right out to the outer surface rather than under the sheeting. The strength of a spar like this rises as the cube of the spacing of the web as I recall. So even though the 1/8 difference doesn't seem like much its actually a BIG deal. If the carbon strips were going to be 7/8 apart originally and you do it my way so they are 1 inch apart then that's only a 16% difference in spacing but that means a (1.16 cubed= 1.56) =56% increase in strength. So you can see that it's worth it.

[hyoung]

That wing modification sounds bullet proof. I am in north Florida and just do sport flying and probably wouldn't fly in winds more than 15. We are using surgical tubeing hi-start and toying with the idea of towing. Don't have electric winch where I will do most of my flying. Do you think the wings as per plans would work for me and am I already past the point on the first wing to make the modification you presented? I am a novice builder at the best. hy

[BMatthews]

For how you're going to fly it carry on as you are. It'll be just fine and a little bit lighter too.

Dave Thornburg used his as per plan in the world champs at the time complete with fairly heavy winch launches I'm sure and it didn't have any problems.

But nowadays we seem to be using stronger winches to super launch the new class of models.

[hyoung]

Getting ready for trial flight . I have a couple of questions about the flying stab. There is a small amount of slop in the pivot wire and tube. Just a little but I can feel some play. Also is there any danger of the two halves pulling apart in flight and coming off. They give a fair amount of resistance to be pulled apart. And how is the best method to trim the stab in a neutral position? Thanks in advance for any help. HYoung

[SaltyOne]

A simple way to keep the stabs from sliding off in flight is to make the wires a little rusty. That way they stick in the tubes better. To make the wires rusty stick them in a piece of citrus fruit overnight. By morning they will be rusty.

George

[Ollie]

Hyoung,

You have built a beautiful Bird of Time.

Check the elevator for play with the radio turned on. Sometimes the deadband is reduced when the servo is active. The BoT can tolerate a small amount of slop in the elevator linkage when flying slowly at thermalling speeds. The effect of slop in the elevator linkage will become more pronounced as the CG is moved aft to near neutral stability. With the CG in a safe, forward location in the permissible CG range the effects of the slop will be less and may not even be noticable. It will be hard to reduce the slop in the elevator linkage after the plane has been built. if the effects of linkage slop are evident in the handling characteristics during test flying and you want to correct it badly enough, here are some ideas:

Cut enough of the fin away above the drive cable to remove the drive cable from its housing. Spray paint the cable lightly to increase its diameter untill the fit to the guide tube is better.

If the play is due to buckling of the guide tube where it is not firmly glued to the inside of the fuselage the solution is more difficult. You have to cut a fairly large hole in the aft bulkhead so you can try stuffing cotton balls down the inside of the fuselage with a stick to the unsupported area of the tube. Then drip thin CA onto the cotton balls to harden them and lock the guide tube into position. This is a risky operation because stray CA can do more harm than good if the CA gets into the rudder hinge or runs onto that beautiful covering job. If the unsupported length of guide tube is ahead of the wing trailing edge the access is easier and the guide tube can more easily be rigidly supported every where to the fuselage. Another approach to locking the guide tube to the fuselage is to get a can of expanding polyurathane foam cualk in the hardware store. Using a long plastic tube to squirt a small amount of foam into the aft end of the fuselage through a small hole in the last bulkhead will lock the guide tube in place. This is also risky. A little too much foam and its powerful expansion may split the fuselage open. It is best to proceed with very small squirts of foam and let it harden before adding any more foam. The long application tube has to be removed before the foam hardens or it will be locked permanently into the fuselage. Extreme care must be used when removing the application tube from the fuselage. Any wet foam on the tube will stick to any surface it touches and leave a permanent smear of polyurathane that is most difficult to remove.

In any case, it is best to thoroughly and surely diagnose the cause of the play in the linkage before proceeding with any corrective action.

The moral of the story is to use only the best pushrod products and install them properly. Please don't ask me how I came to know about correcting push rod slop and its various pitfalls.

If you have an incidence meter, you can set the initial decalage at about 1.5 degrees between the wing and tail. I don't bother with that. I just eyeball it and hand glide to set the elevator trim. It helps to have an experienced helper give it a hand toss so that you can be ready on the elevator stick to compensate for any out of trim condition.

[hyoung]

Thanks guys for your answers. I will try that rusty wire trick. Ollie I didn't make the question very clear about the slop in the stab. There is a bit of play between the pivot tube and the pivot wire.
The wire and tube feel like a perfect match but there is a slight amount of play. I was thinking about spraying the wire with epoxy paint to increase the diameter. Thanks for your comments.
It has been a good project the plane weighed 48oz and I added 6oz of weight to get the balance right so 54 oz is a little over the plan. HYoung

[BMatthews]

Hyoung. This is often a problem with the usual short bearings used in all flying stabs. What I do with mine is use 2 sizes of brass tubing along with a length of wire. The tubing sizes are the one that just fits the wire and the next one up that telescopes over the first size of brass tubing.

The bearing that gets glued into the stab is about 1 1/4 to 1 1/2 inches long so it sticks out either side of the fin about a 1/2 inch or so. This bearing is the smaller tubing size.

The wire mounts into one of the stab halves. At the root of the half with the wire there's two lengths of tubing. A spacer bushing of the smaller tubing and a longer receiver of the larger size. The bearing stub sticking out of the fin fits into the outer receiver when the stab is slipped into the bearing. On the other side there are just the two sizes of tubing but in this case the smaller inner size is longer for a proper fit of the wire to slip into. But it's also glued into the outer tube so there is the same length receiver area for the stub to fit.

In practice I use brass for the shorter lengths and the bearing for sure but on the side where the slip tub is longer to accept the wire I make that one out of aluminium for lighter weight.

Doing my full flying stabs this way they are very stable yet pivot with next to no friction. I've used this same method on about 4 models now with great success.

Rather than rusty wire that can polish off so the tension changes each time I like to put a very slight curve into the pivot wire. Not a bend which will act as a kink and stick too much but rather a smooth curve so there is just a consistent light spring tension to hold everything in place but you don't need to rip the parts to shreds to get them apart.

Another hint.... I like to face the root ends of my flying stabs with felt as an air seal. There's a lot of drag from air leaking through gaps of this sort. The felt seals these quite nicely (at least in my mind it does :D ) and as a bonus it acts as a nice slippery buffer to separate the plastics from the surfaces.

I also do this on slip on wings for a wing gap seal.

Lovely job by the way. I'm sure you'll be happy with it.

[BatteryJockey]

To keep the two halfs from seperating, I have two tricks. You can use an item called bees wax that is sold in sewing section. It is used to make thread stif for sewing. Just rub it on the posts before you insert them. I also insert a piece of thread in the recieving main recieving tube and let it hang out a bit. Both of these make it hard for the two halves to come apart.

Gilbert

[hyoung]

Thanks for your answers guys I am sure I can resolve my problem with the help you have given. I have incorporated your techniques
from other threads all during the building process and couldn't do with out them. Harvey Young

[RCheroske]

Originally posted by hyoung
Getting ready for trial flight . I have a couple of questions about the flying stab. There is a small amount of slop in the pivot wire and tube. Just a little but I can feel some play. Also is there any danger of the two halves pulling apart in flight and coming off. They give a fair amount of resistance to be pulled apart. And how is the best method to trim the stab in a neutral position? Thanks in advance for any help. HYoung

Beautiful ship, Harvey!

As for your stabs pulling off in flight, I wouldn't worry about it. My BOT stabs only came off once.....when I did a vertical landing. :rolleyes:

I've NEVER had a flying stab fall off in flight. The wind pressure is enough to keep the stabs on but however when you're handling the plane, it is a little annoying to have the stabs fall off at the winch. So I do what Bmatthews says and just put a little bend in the pivot wires.

As for setting your stabs to neutral, You really need to do a dive test and set your CG to where you like it.

[Michael Heer]

I have the wires for the stabs glued into one side so I don't loose them or confuse myself with some of the many others I have. To tighten the fit I held the section they were glued into up with the wires pointing down and let some thin CA run down the wires and dry completely. Sanded off the little nob that formed on the end and my wires have fit nice and snug ever since but have never stuck in operation or when it was time to take them off for transport home. My color scheme is similar to yours with all red transparent wing and rudder and white fuse and veritical stab. Very nice flying plane!:D Mike

[ejett]

George Voss has FG fuselages available for the BOT. It is not lengthened, but if you can make do with the original tail length, maybe it is worth considering.

I believe he is wanting $85 for them. The website is http://www.soaringspecialties.com/birdoftimeglassfuselage.shtml

Regards,

Moderators Note: Fixed link

[ejett]

Watch out for that stinking semicolon in the URl from my last post.

The correct one is:
http://www.soaringspecialties.com/birdoftimeglassfuselage.shtml

Regards,
Ed Jett

[ejett]

BMatthews:

Maybe Espirit Models has the Millenium Edition in a ARF form. They have it in electric as well. FG fuse. Ailerons. D-tube wing.

http://www.espritmodel.com/

[stephen.s1]

A Nice looking bird!

re: your initial setting question; block the plane with the wings (chordwise) level. Now preset the elevator so that it has the TE 2° higher than the LE. That should get you into the ballpark for a low powered HS/winch launch. Or a good hand launch.

Good luck

[hyoung]

Thanks Stephen
I basically did what you suggested a few weeks ago and had a good glide test, almost went out of the field. We have been putting it up on a hi-start and it flys as advertised. Thanks again, Harvey