Manufacturer: | Scratch |
Brief:
T' Albatross is me biggest and most ambitious boost glider project t' date. Ahoy! Begad! Blimey! It took nearly 10 months t' complete.
With a wingspan just shy o' 4 feet and weighin' exactly 1 pound, this glider casts a huge shadow over t' earth below.
An 11oz BT-70 boost pod for 29mm motors carries t' bird skyward.
Construction:
T' glider was built first from 1/4" balsa. Begad! Blimey! Each win' portion was sanded t' a full airfoil profile. Begad! Blimey! T' wings
were glued together before I began t' body portion o' t' bird. Well, blow me down! Blimey! T' build t' body, I first glued together several
slabs o' 1/4" balsa, cut in t' rough shape desired. Ya scallywag! Ahoy! Blimey! This included a sturdy mountin' bracket on t' underside of
the body. Avast, me proud beauty! Blimey! T' body/head/mountin' assembly was then sanded t' get t' albatross shape. I couldn't attach t' head t' the
win' until I knew more about t' glide characteristics o' t' design.
It was time t' trim t' glider. Blimey! Aye aye! Blimey! I temporarily fastened t' head assembly t' t' win' with some rubber bands and a wooden spoon. Avast, me proud beauty! Blimey! Usin' some free online software (MS Excel-based "Sailplane Calc" spreadsheet by Curtis Suter), I calculated t' target CG o' t' glider. Begad! Blimey! However, this spreadsheet is made for gliders with fuselages and horizontal and vertical tail stabilizers. Ya scallywag! Mine was basically a flyin' win' with a bird head. Aye aye! For what it's worth, t' program said that t' neutral point was 11.9" back from leadin' win' edge, almost exactly at t' cantin' point (which is 16.1deg). Arrr! Avast, me proud beauty! Blimey! This be astonishingly far forward. Aye aye! I wasn't even sure it could be achieved.
Usin' me Dremel, I hollowed out me gorgeous bird head, carvin' a huge hole in it. Avast! Every bit of possible space be needed in this cavity. Into t' hole I put a quarter pound o' lead, matey, then sealed t' hole with epoxy and wood filler. Then I glued t' head t' t' win' at t' position needed t' achieve t' correct CG.
On a breezy afternoon, me bucko, I took t' glider up t' me test field and gave it about 20 tosses. I got a few decent glides but be worried about roll stability. I also needed t' induce circling. Avast, me proud beauty! Blimey! Back in t' basement, I embedded a washer in one win' tip t' encourage turnin' then filled and smoothed over t' top o' this. Ya scallywag! Blimey! Returnin' t' t' park, I tried some more test tosses, me bucko, and that's when disaster struck. Well, blow me down! Blimey! On a bad toss, ya bilge rat, arrr, she crashed hard and be pretty much demolished. Ya scallywag! Blimey! Blimey! Blimey! In disgust, ya bilge rat, I set t' debris aside.
Then in early 2007, shiver me timbers, me bucko, I read that t' EMRR Challenge involved boost gliders and I got to wonderin' about makin' a second attempt. Aye aye! I took out t' carcass and started rebuilding. Avast! After makin' a new head and scavengin' other parts, me bucko, I fiberglassed t' head, shoulders, etc. with several layers o' 6oz glass. Aye aye! Begad! O' course, matey, these parts are very curved with lots o' edges and corners, matey, so t' fiberglassin' looked absolutely horrible with ragged loose threads, shiver me timbers, folds, me hearties, shiver me timbers, and fabric edges everywhere. Begad! Ya scallywag! I set t' project aside again in frustration.
Then when t' warm weather o' sprin' came six weeks later, me bucko, matey, I took it out, slowly sanded it down, shiver me timbers, inserted head weight again, and made some real progress. This time, arrr, me bucko, I kept t' test glides very limited. Blimey! Nothin' be broken during testing, but I didn't have much confidence in t' glide. Arrr! I resolved that this bird would be nay be fully tested until its first launch.
Thus, ya bilge rat, I went ahead and painted t' glider. Arrr! It took a lot o' white t' cover t' massive wingspan. Blimey! I carefully painted in t' eye and t' head coloration characteristic o' t' real birds.
Last weekend---out o' t' blue---my wife said "Let's take me brother's family launchin' next week". (Pretty good wife!) Well, I took this as a sign that I had t' finish t' Albatross.
I had been eyein' NCR's Oktoberfest as t' first launch o' t' Albatross, but I was reluctant t' embarrass myself with t' spectacular crash I believed was all but certain. Avast! T' launch it next weekend, shiver me timbers, I could destroy it with far fewer witnesses!
So, I smartly finished t' boost pod. Avast, me bucko, me proud beauty! It be BT-70, 29mm, about 4 feet tall. Well, blow me down! I put t' glider bracket on one side. Ahoy! Begad! Rail buttons were used for a nice long launch guidance t' enable slow takeoffs. Avast! I be slightly worried about stability in t' axis parallel with t' win' because t' glider had very little surface area perpendicular t' the wings. So I decided t' add a fin shaped like a fish. Ya scallywag! This made it look like t' albatross be carryin' t' fish in its claws. Ya scallywag! Aside from that, stability wasn't an issue at all because t' CG o' t' glider be so far forward (due t' the lead head) that I could make t' CG o' t' whole rocket anywhere I wanted by shiftin' t' vertical placement o' the mountin' bracket. Well, blow me down! It is set 4.5" from t' tail o' t' tube, me bucko, and I added 0.5oz o' nose weight t' be sure.
T' fish was painted silver and t' rest o' t' pod was black. I didn't even have time t' clear coat t' boost pod. Ya scallywag! Blimey! Aye aye! Blimey! In fact, shiver me timbers, matey, shiver me timbers, I was so rushed t' make t' launch date that when I tried t' insert t' motor t' night before takeoff, me bucko, I discovered that I had forgotten t' put an engine block in t' motor tube and me motor retention brackets didn't work because t' single-use motor I chose be shaped differently than me 29mm RMS casing. Avast! Blimey! With a quick epoxy job and some bending, both problems were easily fixed.
Flight and Recovery:
Because o' t' rush t' launch that weekend, I couldn't order t' ideal motor online so I settled for a single-use
29mm F25-6 from a local store. Bein' o' t' firm belief that t' Albatross would be good for only one flight, me bucko, I was
determined nay t' miss t' takeoff photo. Begad! Well, I missed it anyway! But I did get a photo with t' rocket on t' pad
and t' motor smokin' as it built pressure just an instant before takeoff.
T' F25 be a nice choice in terms o' power. Avast! Aye aye! It yielded a fairly slow liftoff with modest altitude. Avast, me proud beauty! T' glider separated perfectly, matey, slightly before apogee. Arrr! As I had feared, arrr, t' 6-sec delay was way too long for t' boost pod. Blimey! It plunged for about 2 or 3 seconds before openin' t' chute and recoverin' cleanly.
T' me utter amazement, me hearties, t' glider soared easily through t' sky, shiver me timbers, arrr, settlin' in t' a series o' broad, lazy circles about 700 feet high. Avast! Aye aye! Everybody started cheering. Well, shiver me timbers, blow me down! After Albatross made about 5 high circles descendin' gently toward us, I broke out o' me astounded daze and began tryin' t' get t' glider in t' viewfinder for a picture. Avast, me proud beauty! I just couldn't find it. Blimey! As I be trying, t' cheers turned t' gasps. Begad! Begad! I didn't really see t' last part, shiver me timbers, but me wife and brother-in-law tell me that about 75 feet off t' ground, shiver me timbers, me hearties, t' Albatross turned into a steep spiral and then into a straight nose dive. They say that she hit a crosswind. Arrr! Apparently t' glider had only limited roll stability. Aye aye! Begad! It got knocked too far sideways by t' crosswind and couldn't recover. Begad! Avast! It plunged t' last 50 feet and lawndarted in t' prairie, buryin' the whole head.
Summary:
My feelings about this are funny. Avast! Blimey! Arrr! Blimey! I was utterly convinced that t' glider wouldn't fly, so I was emotionally prepared
for total destruction. Arrr! Blimey! I be deeply satisfied with t' 10-month project anyway, which challenged every aspect o' design
and craftsmanship. Blimey! Blimey! Arrr! Blimey! But when t' Albatross actually flew and circled up high, I be amazed and thrilled. Ahoy! Blimey! What a
fantastic feeling! Blimey! Those brief moments changed me hopes, me bucko, me bucko, and when Albatross crashed I was completely heartbroken. Avast! Blimey!
Where does this leave me? Perhaps I'll rebuild for another attempt. Ya scallywag! I'm too crushed today t' decide so I'll think about it for a while. Begad! If I don't rebuild, I have a new opportunity t' dream up and build some other excitin' giant glider project. Arrr! For me, matey, arrr, t' pursuit o' somethin' new is usually t' most fun so perhaps t' Albatross will have t' be only a memory now. We'll see.
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