Yardbird II

[solo6796]

I completed a 126" RES designed and mostly assembled by Jack Womack this spring. I was able to take Third Place at the Mid South with it... It flys great!

The thread on this build was:

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

This wing was to have been the Houston Hawk, but the available fuse was a plug in, and this wing is a bolt on. It sat in Jack's garage unfinished and un sanded for a year or so, till he decided to sell it with an Art Hobby High Aspect fuse. I was ready for another build, so I bought it.

Jack has now re-drawn the wing for better torsion strength, due to a bit of flutter on hard launches. The original wing incorporates .030 and .060 CF sparcaps tapering all the way out. The new wing plans will be sent to Laser Arts for laser cut ribs and webs availability and Jack will sell the plans. I haven't seen them yet.

I used a V-Tail, but Jack has included stab ribs with the set. I suppose any light pod/boom fuse will work. This is a very nice wing with a 3014 airfoil that will ride light lift but handle a very hard launch a la AVA, etc.... Mine weighs about 43 oz. giving it a wingloading of about 5.9 oz/square ft.

Jack will chime in with more details, but this short kit will be a good addition to anyone's hanger for a nice flying/competitive RES ship.

More on the Yardbird II will come soon....

AJ

[solo6796]

Here's a shot of the original.

AJ

[schrederman]

Well,

To qualify what's being put on here, we'll be building a couple of these before offering plans outside the club (Houston Hawks). Probably not more than 2 months, though... Plan sets, if offered, will be $25- plus shipping. Laserartco will have short kits... again... if offered.

I was hit by a computer virus about the time I was getting through with the plans. What a bummer... Not to fear... I have them on plastic, so they'll be back on my PC as soon as I get time to reload my CAD program. What a rip. I would really like to break the fingers of those responsible for viruses... I would be completely done and moving ahead on this if not for 3 nights of recovering everything.

Jack Womack

[solo6796]

My building board is MT... I'll be ready when you are.

AJ

[schrederman]

Rib sets will be available soon from Laserarts. Plans will be available in about 2 weeks.

Jack Womack

[solo6796]

Materials list?

1/2" spar in the middle? Or was it 3/8?

[schrederman]

In Nashville Sunday AM thru Wednesday PM. In Ft Worth Thursday and Friday. Will try to get some plan revision done and copies done this weekend.

Jack

[John Gallagher]

Any word on these plans?

[solo6796]

I pushed the envelope with the Yardbird at the TNT contest in Dallas last weekend. The flutter shook off the tip, but I landed the plane after the tip had already hit the ground, and got a 92 point landing.

I flew miserably for the rest of the contest....

Jack says,

"Well, life is finally returning to some sort of
normal. I have ordered the ribs from Laset Arts,
(finally), and they should be here by the 22nd of
October... I hope. I have received money from 4 of you
and the others will beed to pony up at that time. I am
revising the plans one more time - just adding text -
and I'll have them ready by then.

Sorry this has dragged out so long, but a couple of
hurricanes, a wedding, a wreck, a vehicle burglary,
job interviews, and a trip to Washington D.C. have
gotten in the way. That's mostly behind me and I came
out of all of it with a smile and still have my sense
of humor, though I think the high winds may have
damaged the thermal sensors built into my leg hairs...
bummer...

Jack Womack"

These are still "beta" wings, But I want to try one. If I can get a launch like the Houston Hawk, It'll Kick B***!

AJ

[John Gallagher]

Thanks AJ and Jack. Looks like I got a winter project.

[solo6796]

Bump...

People are talking about the Yardbird in another thread...

[hangerdude1]

Does anyone know if plans and short kits are availabe - if so - where?

Ken

[schrederman]

Since I posted from Nashville, I've been through 2 hurricanes,a wedding, a car wreck, a vehicle burglary, and now I'm into a probable promotion and move. I am attempting to get this going this week. It'll be the first time I've been through something like this without buildiing the first one. I'm going to have to depend on some of the Houston Hawks for that. What else can happen? Well, my check got lost to Laser Arts and his laser is now temporarily out of service.

AAAAAAAAAAGGGGGGHHHH!!!!!!!

I feel better... how 'bout you?

Jack Womack

[solo6796]

"It'll be the first time I've been through something like this without buildiing the first one. I'm going to have to depend on some of the Houston Hawks for that.

Jack Womack"





Don't worry man, we got yer back...

AJ

[tomcat5109]

I haven't seen the plans yet but have been considering two fuselage possibilities for the YardBird II.

The Bubble Dancer kevlar pod and v-mount (Bud Elder), carbon boom (tailboom.com) is one possibility. The pros are: light weight (4 oz), strength and durablilty, good tail moment, easy to assemble. The only con worth mentioning is the wing saddle length allows for a 10.5" cord whereas the YB II cord is about 9" (I think). JW suggests making a fairing. The BD fuse would certainly be the light weight choice.

The new Mantis pod and boom (Terry Luckenbach) and stab v-mount (Bud Elder) is the other possibility. The pros are: strength and durability, robustness, better tail moment for a 127" wingspan, the pylon will fit the S3014 airfoil just fine, slip on nosecone, easy to assemble. The only con worth mentioning is the weight. Mine (pod and boom) weighs 9 oz. Personally I would not worry about a 9 oz fuse. My Houston Hawk #5 fuse weight 9.5 oz and its auw was 62 oz (btw it won RES at TNT this year). A YardBird II built using a Luckenbach pod and boom, JW's Yardbird II wing, full flying stab with Bud Elder v-mount, and top-boom mounted fin and rudder, the auw could be in the mid-50 oz range.

There have been a couple of other fuselage options mentioned in the club, with the Art Hobby 3-meter pod and boom mentioned the most (Alan uses one on the original YB).

These are just my thoughts......I'm not an engineer or designer. Jack Womack designed the wing and stab sizes with the proper moments to build the plane. The fuselage choice is the builder's choice.

Tommy L

[schrederman]

Laser Arts laser is busted for now. We should have sets soon. I will have material lists done and some slight revisions to the building instructions by next weekend. I hope to be able to deliver these sets by then. I'll be in New Mexico all week.

Jack Womack

[solo6796]

I guess I'll just keep the strapping tape on the old wing for now...

AJ

[solo6796]

New Materials list and Building Instructions are on the website.

Laser Arts has a broken laser...

I'm gonna charge up the original Yardbird and fly that sucka' this weekend...

AJ

[solo6796]

Inverted.

[John Gallagher]

New Materials list and Building Instructions are on the website.

AJ

Which website is that?

[solo6796]

www.houstonhawks.org

[schrederman]

For those of you following this thread, I have good news. The plans and ribs are here. Alan or one of the other Hawks will have a set of wings framed up in a few weeks and prove the design improvements. After that happens, the plans will be available from me and ribs/webs available from Laser Arts. As some of you know, I'll be moving to New Mexico in early January. I'll have to check out the plotting facilities that are available there. More designs will be coming. Who knows, I may even do some bagging or something like that...

Jack Womack

[IBWALT]

Well here goes nothing solo. :confused: These are the only yardbirds I know.

[solo6796]

Man! That looks like an old pic... I think Don's gained a little weight since then.. (sorry, Don!)

Jack brought out the Yardbird plans and rib/web sets today. Several Hawks will build one, and we all talked about the design changes. Jack is moving soon to New Mexico, but we all got to fly together for awhile.

Looks like I won't have the only Yardbird anymore...

AJ

[hangerdude1]

AJ

Glad to see the Yardbird II project is moving ahead as I am looking forward to the availability of plans and ribs to build one as a winter project. Would like to add a Yardbird II to my fleet which includes two Houston Hawks. Maybe I should move to Texas?!?!?

Ken

[solo6796]

Jack,

The question has come up as to our materials list. It asks for "quarter sawn" spruce sticks... What's the best explanation for "quarter sawn" ?


AJ

[tomi]

AJ,,

Do you think a 46" fuse will work with the yardbird's wing?

I noticed the fuse that u'r using is the 62" Art Hobby fuse..

If a 46" fuse will work,, I'll definetly build a wing for this fuse I want to get.

-Tomi

[solo6796]

Sorry, Jack will have to answer that one... Seems a little short to me.

AJ

[schrederman]

Moment arms are actually a function primarily of wing chord, rather than span. The fuselage total length is not as important as the length of the tail-moment arm. I recommend about 8 to 12 percent horizontal tail area on a tail moment arm 3.2 to 3.75 X the wing chord. I peronally don't care for long nose-moment arms like the Mantis, but that's a looks thing more than anything. Being an old Nordic flyer, I prefer a short nose moment, though they require more lead. The tail-moment arm is the distance from the center of gravity to the center of control influence of the tail, usually the thickest point in the tail airfoil. Dr. Drela may want to correct me on some of this, and that's OK. I don't claim to know much. My designs do seem to fly OK, though.

So, here goes... Wing chord is 9". That makes the tail moment between 29" and 33 3/4". In my opinion, the longer the better. The nose moment should be about 1.5 to 1.9 X the wing chord...again as a personal preference more than anything. Remember that these are from the center of gravity, and that should start out at about 45% on this wing planform. I am in Ft. Worth and don't have the wing area with me... and you need the math practice, anyway...

Now to qualify all this, a longer span RES ship will handle better with a longer tail, the extra leverage seems to help the rudder control the tip inertia better. The extra leverage will also allow for a smaller stabilator area, within practicality, of course. Looking at Alan Jones' prototype, it has a long tail moment, with a relatively small, 90-degree v-tail. It handles well, to say the least.

Have fun. Please let me know how the new wing kits work. I need to know as soon as possible so the plans can go to others that are waiting...

Jack Womack

[solo6796]

My V tail came off a Super V (2 meter, I think) and is 12 1/2" span and 105 degree.

AJ

[solo6796]

Bought the wood at the LHS today, and my composites came tonight.. Got me a brand new bottle of titebond and new thick and thin CA. The weather for tomorrow is cold and rainy, no good to fly, and I have a partially used bottle of scotch.

I'll make some headway on this here wing!

AJ

[solo6796]

I have the spar started. The laser cutting was pretty good, but some of the plywood didn't get cut all the way through.

I scratched my head a bit over the difference in the W-1R rib height, vs the others. Then I realised that I didn't have to install the whole set of ribs at this point. Just the root ribs go in right now.

The pics are pretty self explanitory, You will have to shorten the 1st set of webs tho, to account for the extra width of the bolt beam laminate.

Got a good start on it and will continue in the morning...

AJ

[Christian Baron]

AJ,
looks like the rips are to short at the trailing edge? It it because of the full covering with balsa sheets afterwards?
What airfoil is used for the Yardbird?
Sorry for all the questions.
Christian

[solo6796]

Yes, the trailing edge will be fully sheeted. The wing uses S3014 airfoil.

AJ

[erichj]

AJ
I have yet to start on my HH, will be home soon and hope to do some building. Nice going on your YB. Please tell me What is "Cabosil" (never heard of it), where do I get it and what is it for, a filler?? :confused:
Merry Christmas! :)
Erich

[solo6796]

Erich,

It's a filler, very light and stronger than microballoons. It makes epoxy the consistency of toothpaste..

http://www.eagerplastics.com/cab.htm

AJ

[solo6796]

More done today... A small hang up is that the ply joiner box parts don't come with the short kit. I had to run over to Harper's and he let me use his jigsaw and disk sander to produce them. Steve came by and looked over my progress, and we talked for a while.

This morning, I wrapped the root area with kevlar braid. Later, I got the rest of the ribs and shear webs installed with thickened epoxy. Remember to taper the tops of the webs to match the airfoil.

Talked with Jack a few times about this and that.. A few more details to work out.

[solo6796]

I just set the old Yardbird wing next to the new one to check the differences. The most obvious is that the rib spacing is reduced to 2" from 2 1/2". The spar is now moved 1" aft of the old location also. I suppose the CG will change slightly because of this.

Jack, any thoughts on where to balance this puppy when I'm ready to re- maiden?

AJ

[schrederman]

Alan,

Check where it balances with the old wing and make it balance in exactly the same place. I suspect it's about 45% of the root chord of that wing. Let us know. I hadn't calculated the cg and I'm getting lazy in my old age... The wing planform and size didn't change. That part of the design was proven with the original. I still say I sold it too cheap!!!

Jack

[solo6796]

I plan to just drill the mount holes just like the last one, and put it on my existing sailplane. I was thinking it may need a little more noseweight, since the spar is an inch further back now.

AJ

[solo6796]

While I was having my coffee this morning, I added the joiner boxes and laminated a little CF on the trailing edge.

I cut the plywood 5" long and tapered the inner end, then rounded off the outer edge for wrapping. I think I will use that MPI CF to wrap this area and then I won't have to relieve the sheeting so much. I nearly sanded through the center section sheeting in the middle, but I plan to put a fiberglass wrap on top of the sheeting at the root anyway.

A 1/2" shear web goes right next to the rib, and then I used another for a spacer at the end. More thickened epoxy and clamps to hold it. I left the spar material it's original length. When all this is dry, I will cut the box to the proper length all at once.

The TE is laminated with more of the MPI CF using slightly thinned laminating resin, applied with a brush. When done, I covered it with saran wrap, laid my metal ruler on it, and applied weight till it cures. It will be this afternoon before it is hard enough to do any more work on it.

[Hawkmember]

AJ, nice job and good progress ! Ordered my spars yesterday and will go to the LHS for wood on my next days off. I'll go with the ART Hobby fuse like Schrederman said but will have a bottle of Crown SR instead of Scotch for alignment purposes.
DR.

[solo6796]

Yeah Baby!

Joiner boxes are wrapped. ready to finish sheeting the center after I install the spoiler servos. Not much room in there, now that the spar has been moved back... I think my direct link method will work.

AJ

After I applied the resin, I put the saran wrap and weights back on, to flatten the top and bottom more during the cure. They should come out real smooth, and very little will need to be done to adjust the sheeting over them.

[schrederman]

Excellent job so far... I wish I was building one, but alas, I had to get new tires for AZ today. She's all packed up for her trip to Caprock Soaring Club in the first week of January. Besides, I has some last minute "Oh I want one" comments from some Hawks so I am without ribs/webs for my own project, but not for long. I am going to draw up a fuselage pod and go ahead with the tail ribs, once I get settled. Look for a full kit from somewhere... soon... like April or May... or...

I'm going to decimate Lone Star Balsa's stock soon... but that's for my building stock.

More later

Jack

[solo6796]

Thank you, Master.

I wish I had used this to wrap the center section, now. Much cleaner.

AJ

[schrederman]

It did look a lot flatter. It will be ok, like you said earlier, with the fiberglass wrap and all, it should be indestructable...

Cactus Jack

[solo6796]

Starting the top sheeting, and fitting the spoiler servos. There isn't much room for servos now that the spar has moved back. I'll have to set it up with the servo arm pushing on the spoiler blade. There's no room for linkage.

AJ

[solo6796]

Wellllll..... I was scratching my head over the leading edge treatment for the top sheeting, and had to bother the Master about it. The leading edge is a 1/4"X1/4" hard balsa stick and the sheeting couldn't butt against it or make the bend to glue on top of it.

Easy! Just plane and sand the stick to the curve of the airfoil. Then, starting in the middle, tack the sheeting to it with CA. Work your way to the ends and then get a run of CA down the length. Took about 5 minutes.

I then applied Titebond to the tops of the ribs and weighted it down to dry with phonebooks and my Yuletime weights.

The material you plane off the 1/4" stick is replaced with the 3/32" sheeting and the airfoil nose is almost there before your start sanding it. To boot, the CA looks like it polymerizes the leading edge for ding resistance. Not much sanding will be needed to finish the leading edge.

After seeing it, I remembered the original Yardbird wing I bought from Jack. I had to finish sanding it and I remember it was different from the Hawk's leading edge.

I think I have the servo setup figgered out. I'll probably do that tomorrow night.

AJ

[solo6796]

Center panel sheeting is complete. Jack H. is going to let me use his jigsaw to cut off the excess spar this evening.

On to the outer panels. I plan to build both at the same time.

AJ

[Christian Baron]

Would be interesting to get the weight of your center wing panel.
Christian

[solo6796]

The old wing is 13 oz. That includes servos, wiring, covering and joiner receiver potted. This one is at 11 oz. including servos and wiring. Looks like it will come in very close to the original after finish sanding, covering, and reciever tubes.

Cleared the board and started on the outer panels. For the tapered spars, stack two hard balsa 1/8X1/2 between two spruce of the same size. Clamp one end together and to the bench, and put just a drop of CA on the other end to hold them together. I used a razor plane to make the taper down to 1/8" on the outer end. Got it close and then used the sanding block. The supplied shear webs require some sanding as some of them are too high.

AJ

[schrederman]

It's tough watching someone else go out with your girl... Feeling a little dejected about moving, just about now... But she sure is looking good...

Jack

[solo6796]

These outer panels will be lighter than the original. It had .060/.030 CF and epoxy all the way out. We're using Titebond with spruce and balsa on this one.

Hey!

I found a 5/16" aluminum rod and brass tube in my stockpile! I'll be ready to do the joiners as soon as the outers are ready. What's the best way to set the tubing for accurate dihedral?

AJ

[schrederman]

The outer carbon spars on the original wing were overkill. I'm afraid the 5/16 aluminum rod will be too small, especially the way you launch!! I designed it for 5/16 steel. Be careful.

Jack

[solo6796]

OK, I'll go steel... But the outers have no carbon and are just spruce and balsa. Ya mean I might bend the aluminum? It's that good K&S stuff ya know...

I still need your method of potting the joiner with accurate dihedral for when I get to that point, Master....

AJ

[schrederman]

I use a radial arm saw and set the panels up very carefully. I actually saw them to the correct dihedral angles and finish sand the joint. You can do an adequate jobe with just a sanding block, but it sure is time consuming. Then I pot the joiner tube box on both sides ot the poly joint with enough epoxy and cabosil to fill the cavity. I will have the two plywood ribs mated and the plugged (both ends) tube inserted in them, with the index pin in place. It needs about 1/64 cleadance between the ribs so you can saw the tube off. I use the excess epoxy to glue the plywood ribs to the rest of the structure, prop it all up and let it cure. You may have to weight it and pin things to keep everything perfect for the curing period, but when done, saw the tube in half, file the ends smooth, insert your joiner, and you have a perfecty matching poly joint, with a replacable joiner. Of course you have to be careful to keep the epoxy where it's supposed to be and keep it off of everything else, but that's doable. The plywood ribs should be set up for the 11/32 joiner tube to be in the top, aft corner of the box, which should allow a 5" joiner to be straight and yield 8 degrees dihedral for the outer panel. That should give you a perfect fit for a 5/16 hardened steel joiner rod. There'll be no slop with this setup. The loose fitting carbon rods were a problem that I didn't anticipate on the prototype wing.

Hope that helps.

Jack

[solo6796]

I messed up and glued the spars to the outer sheets before making and wrapping the joiner box. I think It will hold with 3 or 4 wraps of CF secured by thin CA on each end.

I have the top sheeting on the outers and the trailing edge for the tips drying with weights on them. The little joiner for the tips are made of plywood and have to be bent to match the sweep of the spar there. Get 'em a little wet and they bend pretty easy, especially while re-drying them with a hair dryer. Don't bend them too fast, or they'll break. Then I clamped them down overnight over a 1/4" stick. I had some laminating epoxy left over from a batch I made for the trailing edges, so I brushed a little on them.

I don't really like the way my TE came out on the center panel. It curled up some, but I think it's fixable. For the outers, I laminated some 3/4 oz fiberglass cloth between the sheets and they are real stiff. I thinned the epoxy quite a bit.

For the tips, you have to make your own 1/16" shear webs. It's not a lot of fun making vertical grain webs only 1/16-1/8" high. I used thick CA for those, so I could adjust the final height with a little sanding stick I made. The spars out there are only 1/8" square balsa and spruce. After sheeting the tops of those, all I have to do is carve the tiplets.

Everything is under weights, right now, so I'll post some more pictures later...

[Hawkmember]

AJ, would you post a pic of the center section trailing edge, a cross section shot so we can see the T/E.
BTW, how in the world do you post a pic here ? I was forced to go with the wife in a beauty supply store, and found some handy looking sanding sticks for nails that I wanted to show everyone.
DR.

[solo6796]

I used that unidirectional CF tape I had on the center section. It really doesn't do a lot of good. I should have used CF mat as the instructions say.

Can't change it now, tho.. I may have to put some glass on the outside, but I don't want to unless forced into it.

On the outers and tips, I used 3/4 oz fiberglass, and it worked pretty good. One of these days, I'll have to get the right stuff and do things right. Just couldn't wait, Ya Know?

Both will look better after they're sanded.

AJ

[schrederman]

Soooooo....

Did the ribs and all match the plans OK? Other than the shear webs being too tall in a couple of spots, did you have any other problems with the parts or plans? Inquiring minds want to know. There are a few folks waiting for plans and Brian at Laset Arts wants to release part sets for purchase... and thousands of lives are at stake... well, probably not...

Jack

[Christian Baron]

The airfoil in the last picture is looking terrible! Can you get the right shape by sanding? Like I wrote some threads before, the ribs could be longer in direction of the TL, that would better fit to the airfoil shape.
Christian

[solo6796]

The ribs all worked pretty good.

There are 4 #18 ribs, but they aren't labeled...

Most of the webs in the outer are too tall.

It would be nice to have the ply for the joiner boxes included in the laser cut set.

The sheeted trailing edges are fiddly, but I'll deal with it.

I think the little joiners for the tiplets should have been two 1/64" ply laminated together instead of the 1/8" ply. Easier to bend, and more plies.

The instructions are directed to an experienced builder, which I am not, so I had to ask about some "how to's".

It would be nice to have the rib numbering on the plan outside the area where the sheeting goes.

I haven't sheeted the tips panels yet, but the ribs there are little, and VERY light balsa and it is a delicate piece. I may put in some gussets or something at the TE. I'm afraid the ribs will break when I start sanding the TE.

Since I'm wishing, I hope I get this thing done before you move, so you can be there for the maiden.

AJ

[solo6796]

The airfoil in the last picture is looking terrible! Can you get the right shape by sanding? Like I wrote some threads before, the ribs could be longer in direction of the TL, that would better fit to the airfoil shape.
Christian

I haven't done the finish sanding, and the ends are pretty funky on that last bay. I put the plywood end over it, and there is plenty of sheeting left to make the correction. The main reason for the end looking so bad, is that it's a cut rib attached to the joiner box, which I didn't get exactly centered on the box. The rest of the airfoil looks real good.

I agree with you on the TE, they seem too long for the ribs. I'll take some more pix after the finish sanding... But I think it will be OK.

AJ

[Christian Baron]

Thought to make it easier for the next who will build the Yardbird, maybe I.
Hard work for you to sand the whole wing, good luck. But you are doing a good job and the result will be very nice, I'm sure.
Merry Christmas
Christian

[solo6796]

Tiplets carved... AJ Style...

[solo6796]

Been sanding on the patio, and getting close ... The tiplet joiners are in place but not secured, because I have a bit more adjusting to do at the joints. Leading edges are getting close and so are the TE.

This is the most tedious part for me. But the difference in appearance after sanding is amazing. I figure on sanding for a couple days to get everything just right. Need some cabosil for the joiner boxes cuz I'm just about out. Also need some better rods. Jack said the stuff at Home Depot is too weak. I have aluminum, but he says 5/16 aluminum is too weak also...

It's just little stuff now, and I'll be ready for covering.

[little flyer]

Your wing looks great, reminds me of a K2 light wing. Happy Holidays!

[schrederman]

Careful,

Your pool filter will be full of balsa dust...

Jack (in Ft Worth for the holidays)

[solo6796]

HA!

I was dippin' balsa chips out this morning... I carved the tips out there last night.

Got the outers to mate well to the tip panels, and a lot more on the TE and LE done. I'm sanding down just till the CF shows through the balsa. Looks purty cool!

ZOOOOOOOMMMM.....

AJ

[John Gallagher]

Can you summarize the differences between the Yardbird and the Houston Hawk? For someone looking to build one, why choose one over the other?

[schrederman]

The Hawk is a conventional wood build except for the carbon fiber spars. The Yardbird is more like the Bubble Dancer though a lot less fussy. The Hawk has plug-on wings and a center joiner, whereas the Yardbird has a bolt-on wing and 3 panels. The Hawk is a heavier wing loading with the S3021 airfoil and the Yardbird is lighter with the S3014 airfoil. I'll probably build a set of Hawk wings with the S3014 foil for West Texas and New Mexico. I may be sloping one off Guadalupe Peak this spring... My vote is for the Hawk for now because a short kit is commercially available. The Yardbird will be a good performer but we haven't gotten all the bugs out just yet... workin' on it as we speak. I may do a set of Hawk wings with the popular SD-7037 when I get settled.

Jack Womack
designer of both...

[schrederman]

Our house goes on the market on the 28th and the realtor said it won't last long. I have to be in Albuquerque on the 3rd to hire a new technician... AAAGGGGHHHHH!!!!!

It's really happening!

JW

[Hawkmember]

well you should be knee deep in dust since your last entry !
I'm having launch withdraw, need to fly BAD !
DR.

[John Gallagher]

The Hawk is a conventional wood build ...

Jack Womack
designer of both...

Thanks for the answer Jack.

[solo6796]

I got the spoiler servos installed this morning. There's just enough room for a .45" wide servo to fit. I used the E-flite S75's I found at the LHS. They are lighter and stronger than the HS56's I have in the original wing.

I had to cut the mounting lugs off, and made a little shelf/box of 1/32" ply and 1/64" balsa. A little dab of goop holds them solid. The servo arm pushes the spoiler up. I used this method on the original and on my BoT, with no problems. The servo is replaceable and I can adjust the arms as needed. Just be sure you have the servos centered and know where the arm position is before they are secured in place.

[bobby legue]

Hey solo6796,
The next time you install those servos try turning them 1/4 turn so that the arm is slightly behind the spoiler blade. I had a helluva time trying to make the spoilers work in my Victory and finally came up with this solution- and they work great!! :D I did use Dubro extra long servo arms they come up to the top of the spoiler. Heres the kicker, I use the arm with the last hole slotted open on the under side , cut with a Zona saw , and hook a dental rubber band for braces to the spoiler via a small piece of ply fashioned to a second hook that is glued to the spoiler center. It has been recommended that you insall a rub block on the back side of the spoiler so the arm wont chaff a groove in it , I didnt as my spoilers are made of carbon-Kevlar and no wear is showing.
Spoilers done in this fashion WILL STAY CLOSED ON LAUNCH
That solution really made my day!
Good skies to ya,
Bob

[solo6796]

Sounds like a good idea. My prob was that there was no room to angle the servo between the spar and sub spar behind the spoiler. I will imbed a 1/8" rare earth magnet in the rear of the spoiler bay and just tape a piece of cutoff blade onto the bottom of the spoiler to keep it shut. Works for me.

AJ

[JimHSoars]

Jack,

The question has come up as to our materials list. It asks for "quarter sawn" spruce sticks... What's the best explanation for "quarter sawn" ?


AJQuarter, plain, and rift all refer to how the lumber is sawn relative to the round shape of the tree's bool, the part of the tree between the expansion area of the roots and the first fork of the branches. Here (http://www.allwoodwork.com/article/woodwork/plainorquartersawn.htm) is a description of quarter and plain sawn lumber.

The advantage of using quarter sawn lumber is that it is less pron to warping and change in size due to changes in the relative humidity. If you want to go off the deep end you can coat all of your non-glued wood surfaces with Shellac (http://www.shellac.net/) which is a very good barrier to water vapor exchange with the air. It keeps the water vapor out (or in if you go to Arizona) thus limiting the change in dimension and possible warping.

There is some what of a learning curve about shellac so take the time to look it up on the web.

Jim

[solo6796]

same same Straight Grained. Makes sense.

AJ

[solo6796]

Sanded the joints for the tip panels and epoxied them together. The little bent ply joiner just fits and determines your polyhedral angle.

I learned to protect the sheeting with masking tape before starting this process.

The center panel ends have cleaned up well with more sanding. I wetted the TE last night and clamped it down to the bench with my metal ruler below, and hardwood sticks on top. That took the curl out of the TE. The spoiler blades are fitted. Just have to fiberglass the center bolt area, pot the main joiners, finish sanding, and cover.

[solo6796]

To reinforce the bolt area just a little, I applied a fiberglass wrap. This helps a bit to resist wear in the wing saddle area.

Masked, applied laminating resin, glass, blot off with paper towels.

I got one dang bristle stuck under the glass on the top. I'm going to just leave it. It's in the direction of the air flow (like that matters). Anyway, it will sure be unique...

Gettin' ready to pot the joiners, but I'm still out of cabosil. I want to have the outers mated before I do the final sanding. Anybody have some cabosil I can borrow tomorrow? I promise to return it next Tuesday.

I ordered the steel joiners from Sky Bench. I have aluminum on hand to do all the testing/sanding with. May keep both on hand. I wonder how the wing performs with steel VS aluminum joiners in there? Jack says the aluminum will bend the way I like to launch.

AJ

[tomcat5109]

Alan, I have some colodial silica from West Systems you can borrow. I can return the frequency pin and pick up my retriever battery at the same time.

Tommy

[schrederman]

I have Cabosil and a joiner... but you'd have to drive out here to get it. I have to fly out to ABQ at about 2:00 tomorrow, leaving from Hobby. I gotta leave here about 11:30. I won't get back until Thursday, about noon. We're leaving Friday to take the real glider to Littlefield, and continue on to Clovis for our house-hunting trip. One of the ones we're looking at has a 1500 sq. ft. shop building... WOW!!!

See ya later... you have my number if you want to come get cabosil.

Jack

[schrederman]

Alan,

How did the ribs work for the outboard panels? I am interested in the way the top sheeting fit the recesses behind the spar. Did you have any trouble with the recess making a straight line for the sheeting to follow?

Jack

[solo6796]

Alan,

How did the ribs work for the outboard panels? I am interested in the way the top sheeting fit the recesses behind the spar. Did you have any trouble with the recess making a straight line for the sheeting to follow?

Jack


No problems with the sheeting. Just measure twice, cut once, er, maybe twice on one of them....

The sanding is coming along and making everything look better. The leading edges are close, now. I'm using the template for them.

This will be a nice wing....

I added a photo for the original wing. The added sheeting and closer rib spacing is apparent.

AJ

[schrederman]

Howdy from Belen, NM... How's the torsional stiffness of the panels? I think it will be about as good on the new wing uncovered as the old wing covered. Use Monokote and teh flutters will be gone for sure... Looks good.

Jack

[solo6796]

Monokote? I already bought the Ultracote.

You're right, they are much stiffer than the old ones. Taking my time on the LE sanding. I want it to be right on.

How's NM? Saturday was GREAT flying. A bunch of Hawks showed up to fly and we had more visitors...

Got a bigger motor and huge lipo for the Ellipsoid 2.8 meter, and beat Walter in a challenge match with his lipo/Mega powered Windancer. They both climb vertical, now.

Bought Steve's Yardbird plans and ribset... I have a spare.

AJ

[schrederman]

Glad to hear the wings are stiffer, though I was sure they would be. New Mexico is terrific. I can see some opportunity to do some interesting stuff out here. I am thinking of building an XC sailplane. There are some really wide open spaces out here.

I gotta find a Ridgeways out here to do my plots, and a Kinko's to do copies. When we see your wings fly successfully, I'll get into letting the plans go out to those that want them.

I'll be back in Houston Thursday, only to turn around and drive back out with my sailplane in tow on Saturday... See ya.

Jack

[solo6796]

Getting ready to pot the joiners last night and thought I had a problem. I couldn't get the dihedral I wanted, so I compared to the old wing and called Mr. Womack.

Looks like it will be best to use only about a 4" joiner tube. The space I left in the outer (3") limits the dihedral angle available. So when building the joiner box in the outer panels, use a full size SW3 and you'll be OK. I will fill the area with another shear web and a bunch of epoxy splooge. If you need to relieve the upper spar a little with the Dremel it's OK, and you will have more than enough dihedral available. Just be sure to fill the cavity completely with thickened epoxy, leaving no voids.

I took some pics of the new and old wings set up on the table for comparison. The new wing is much stiffer in torsion and will weigh only a couple oz. more. The Yardbird can use the extra weight. Mine flew great at around 43 oz. but I felt like it could use ballast in any kind of wind. We'll see soon enough.

I need a belt sander or other means to sand the ends more square. They are a little off yet, so, I probably won't set the joiners tonight. That carbon is tough to sand right next to the balsa.

AJ

[solo6796]

The joiners tubes are epoxied into the boxes, and the 5/16" steel rods were cut to length. My roto-zip with the 3" metal cutting wheel came in handy for this. The hacksaw would barely scratch the hardened steel.

I'm using some leftover Sullivan carbon pushrod material for the alignment pins. They are very stiff for this purpose, but have a bit of give on shock loads. This wing will have one in front and one behind the spar.

I've begun the finish sanding, and will cover and mount the wing this week. Maiden will be this weekend, if not sooner.

The wing now weighs 24 oz. without covering. (The steel rods came in at nearly 3oz....!) The rest of the plane weighs 21 oz. We will come in between 45 and 50 oz., I'm not sure what the covering will weigh.

[JimHSoars]

The joiners tubes are epoxied into the boxes, and the 5/16" steel rods were cut to length. My roto-zip with the 3" metal cutting wheel came in handy for this. The hacksaw would barely scratch the hardened steel.AJ

What type of steel did you specify for the rods to get stiff enough rods for the application.

Jim

[JimHSoars]

While I was having my coffee this morning, I added the joiner boxes and laminated a little CF on the trailing edge. [...]

The TE is laminated with more of the MPI CF using slightly thinned laminating resin, applied with a brush. When done, I covered it with saran wrap, laid my metal ruler on it, and applied weight till it cures. It will be this afternoon before it is hard enough to do any more work on it.AJ;

Which laminating resin are you using? There are several avaliable; some very expensive and others for much less, but with not such good reputations. For a bottem feeder such as myself, less expensive is good, if it works. :rolleyes:

Thanks
Jim

[solo6796]

Jim,

The joiner rod is from Skybench and is really nice stuff...

http://www.skybench.com/

The resin I used is from the LHS and just called "20 Min. Finish-Cure Epoxy". The bottles say it is distrubuted by Bob Smith Industries. For the little laminating I do it is just fine. It is a little thinner than the other LHS stuff, and I used a bit of denatured alcohol to thin it a bit more. I know there is better stuff out there. The size and price was good, too

AJ

[Hawkmember]

AJ, wing looks good. taking it out sat ?
I'm ready to start on my wing but I may have a problem, I ordered 4-6 lb wood. Will that work ? It came in, but sure feels light !
Schrederman , how bout a little input on the wood........ thanks, DR.

[solo6796]

I would think you'll be OK. Make sure the spar material is good.

Got the center section covered tonight. We be flyin' it Saturday, if the weather cooperates.

AJ

[schrederman]

I used to use 4-6 lb wood, but that was in my teens, flying free-flight models. I don't recommend it for our rough and tumble R/C stuff. For the outer panels, you might get by with it. I'd get some medium 7-10 lb stuff for the rest. As AJ said, be sure uour spar materials are as hard and as straight-grained as possible. The leading edges need to be pretty hard, too.

Jack

[Hawkmember]

Thank you Jack, I'll send this stuff back tomarrow.

DR.

[schrederman]

That steel that Skybench uses is really strong stuff. That's why I decided to use it. A 4" joiner at that span station will be plenty.

Jack

[schrederman]

Signed the deal for our new digs in Clovis, NM today. I'm amazed at the price differences between Clovis and Houston. Real estate prices are much higher out there. Our home here is showing very regularly but no offers yet. We have a firm offer from our relocation group but it's a lowball. It's just not a good time to be trying to sell a home. We'll be gone for good about Feb. 14 or so. Our closing is Feb. 16 and we'll move in the 17th and 18th. I doubt I'll be doing much modelling for some time. My glider's already in it's new hangar and it's looking awfully inviting out there... I can't wait for summer and 17000 ft. cloudbases.... YEEHAW!!

Jack

[solo6796]

Jack,

I'm still going to make some joiners out of Aluminum, too. These steel ones can be considered ballast as well.

Mounted the wing to my Fuse today. It is working out very well.. I used the existing front mount, and made another for the rear.