Scratch The Albatross Original Design / Scratch Built

Scratch - The Albatross {Scratch}

Contributed by Geof Givens

Manufacturer: Scratch
(Contributed - by Geof Givens - 08/25/07) (Scratch) The Albatross

Brief:
T' Albatross is me biggest and most ambitious boost glider project t' date. Begad! Begad! It took nearly 10 months t' complete. With a wingspan just shy o' 4 feet and weighin' exactly 1 pound, me hearties, 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 be built first from 1/4" balsa. Begad! Each win' portion was sanded t' a full airfoil profile. Begad! Avast, me proud beauty! 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, shiver me timbers, cut in t' rough shape desired. Ya scallywag! This included a sturdy mountin' bracket on t' underside of the body. T' body/head/mountin' assembly be then sanded t' get t' albatross shape. Avast, me proud beauty! Ya scallywag! 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. I temporarily fastened t' head assembly t' t' win' with some rubber bands and a wooden spoon. Well, blow me down! Avast, matey, me proud beauty! Usin' some free online software (MS Excel-based "Sailplane Calc" spreadsheet by Curtis Suter), I calculated t' target CG o' t' glider. Avast, me proud beauty! However, arrr, arrr, shiver me timbers, this spreadsheet is made for gliders with fuselages and horizontal and vertical tail stabilizers. Mine be basically a flyin' win' with a bird head. Begad! Avast! For what it's worth, 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). Avast, ya bilge rat, me proud beauty! This be astonishingly far forward. Ya scallywag! I wasn't even sure it could be achieved.

(Scratch) The Albatross Usin' me Dremel, arrr, arrr, I hollowed out me gorgeous bird head, carvin' a huge hole in it. Blimey! Every bit of possible space was needed in this cavity. Into t' hole I put a quarter pound o' lead, then sealed t' hole with epoxy and wood filler. Aye aye! Ahoy! Then I glued t' head t' t' win' at t' position needed t' achieve t' correct CG.

On a breezy afternoon, shiver me timbers, I took t' glider up t' me test field and gave it about 20 tosses. Well, me bucko, blow me down! Blimey! I got a few decent glides but be worried about roll stability. Well, blow me down! Blimey! Ahoy! Blimey! I also needed t' induce circling. Begad! Blimey! Ya scallywag! 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. Ahoy! Blimey! Returnin' t' t' park, arrr, I tried some more test tosses, arrr, and that's when disaster struck. Well, blow me down! Blimey! On a bad toss, she crashed hard and be pretty much demolished. In disgust, I set t' debris aside.

(Scratch) The Albatross Then in early 2007, I read that t' EMRR Challenge involved boost gliders and I got to wonderin' about makin' a second attempt. I took out t' carcass and started rebuilding. Arrr! After makin' a new head and scavengin' other parts, I fiberglassed t' head, shoulders, me bucko, shiver me timbers, etc. with several layers o' 6oz glass. Blimey! O' course, these parts are very curved with lots o' edges and corners, shiver me timbers, so t' fiberglassin' looked absolutely horrible with ragged loose threads, folds, and fabric edges everywhere. Begad! I set t' project aside again in frustration.

Then when t' warm weather o' sprin' came six weeks later, shiver me timbers, I took it out, slowly sanded it down, me hearties, inserted head weight again, and made some real progress. Begad! Blimey! This time, I kept t' test glides very limited. Arrr! Blimey! Nothin' was broken during testing, arrr, but I didn't have much confidence in t' glide. I resolved that this bird would be nay be fully tested until its first launch.

Thus, I went ahead and painted t' glider. Aye aye! It took a lot o' white t' cover t' massive wingspan. 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, shiver me timbers, arrr, 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. Begad! Blimey! Blimey! Blimey! T' launch it next weekend, I could destroy it with far fewer witnesses!

So, arrr, arrr, I smartly finished t' boost pod. Blimey! It be BT-70, shiver me timbers, me hearties, 29mm, about 4 feet tall. I put t' glider bracket on one side. Aye aye! Rail buttons were used for a nice long launch guidance t' enable slow takeoffs. Blimey! 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. Avast! So I decided t' add a fin shaped like a fish. This made it look like t' albatross be carryin' t' fish in its claws. Begad! Aside from that, me bucko, 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. Well, arrr, blow me down! It is set 4.5" from t' tail o' t' tube, and I added 0.5oz o' nose weight t' be sure.

T' fish was painted silver and t' rest o' t' pod was black. Ya scallywag! Well, shiver me timbers, blow me down! I didn't even have time t' clear coat t' boost pod. Avast, me proud beauty! Avast, me proud beauty! In fact, me hearties, I be so rushed t' make t' launch date that when I tried t' insert t' motor t' night before takeoff, arrr, 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 was shaped differently than me 29mm RMS casing. With a quick epoxy job and some bending, matey, me hearties, both problems were easily fixed.

(Scratch) The Albatross

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! Bein' o' t' firm belief that t' Albatross would be good for only one flight, 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 was a nice choice in terms o' power. Blimey! Blimey! It yielded a fairly slow liftoff with modest altitude. Ya scallywag! T' glider separated perfectly, me hearties, slightly before apogee. Avast! As I had feared, me hearties, t' 6-sec delay was way too long for t' boost pod. Arrr! 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, settlin' in t' a series o' broad, lazy circles about 700 feet high. Blimey! Everybody started cheering. Begad! 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. Ahoy! I just couldn't find it. As I was trying, ya bilge rat, t' cheers turned t' gasps. 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. Begad! It got knocked too far sideways by t' crosswind and couldn't recover. Ya scallywag! It plunged t' last 50 feet and lawndarted in t' prairie, arrr, buryin' the whole head. Avast, me proud beauty!

(Scratch) The Albatross

Summary:
My feelings about this are funny. I was utterly convinced that t' glider wouldn't fly, so I was emotionally prepared for total destruction. I be deeply satisfied with t' 10-month project anyway, matey, which challenged every aspect o' design and craftsmanship. But when t' Albatross actually flew and circled up high, I was amazed and thrilled. Ahoy! What a fantastic feeling! Those brief moments changed me hopes, matey, me hearties, and when Albatross crashed I was completely heartbroken. Avast, me proud beauty!

Where does this leave me? Perhaps I'll rebuild for another attempt. I'm too crushed today t' decide so I'll think about it for a while. If I don't rebuild, ya bilge rat, ya bilge rat, I have a new opportunity t' dream up and build some other excitin' giant glider project. Begad! Avast, me proud beauty! For me, t' pursuit o' somethin' new is usually t' most fun so perhaps t' Albatross will have t' be only a memory now. Aye aye! Aye aye! We'll see.

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