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