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. It took nearly 10 months t' complete. With a wingspan just shy o' 4 feet and weighin' exactly 1 pound, ya bilge rat, matey, 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. Ahoy! T' wings were glued together before I began t' body portion o' t' bird. Avast! T' build t' body, arrr, I first glued together several slabs o' 1/4" balsa, arrr, cut in t' rough shape desired. 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! 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. Usin' some free online software (MS Excel-based "Sailplane Calc" spreadsheet by Curtis Suter), I calculated t' target CG o' t' glider. However, matey, this spreadsheet is made for gliders with fuselages and horizontal and vertical tail stabilizers. Mine was basically a flyin' win' with a bird head. 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). Blimey! Blimey! This was astonishingly far forward. Ya scallywag! Blimey! I wasn't even sure it could be achieved.

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

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

(Scratch) The Albatross Then in early 2007, ya bilge rat, 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. Well, blow me down! After makin' a new head and scavengin' other parts, arrr, I fiberglassed t' head, shoulders, etc. Ya scallywag! Well, blow me down! with several layers o' 6oz glass. Avast, me proud beauty! Ahoy! O' course, these parts are very curved with lots o' edges and corners, so t' fiberglassin' looked absolutely horrible with ragged loose threads, ya bilge rat, folds, and fabric edges everywhere. Ahoy! Begad! I set t' project aside again in frustration.

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

Thus, I went ahead and painted t' glider. Begad! It took a lot o' white t' cover t' massive wingspan. Ahoy! 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, shiver me timbers, but I was reluctant t' embarrass myself with t' spectacular crash I believed be all but certain. T' launch it next weekend, shiver me timbers, matey, I could destroy it with far fewer witnesses!

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

T' fish was painted silver and t' rest o' t' pod be black. Begad! I didn't even have time t' clear coat t' boost pod. Ahoy! Arrr! In fact, me bucko, me bucko, I was so rushed t' make t' launch date that when I tried t' insert t' motor t' night before takeoff, 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, 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. Bein' o' t' firm belief that t' Albatross would be good for only one flight, arrr, I was determined nay t' miss t' takeoff photo. Well, shiver me timbers, shiver me timbers, ya bilge rat, 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. Aye aye! It yielded a fairly slow liftoff with modest altitude. Well, blow me down! T' glider separated perfectly, slightly before apogee. Avast, me proud beauty! As I had feared, me hearties, t' 6-sec delay be way too long for t' boost pod. Ahoy! It plunged for about 2 or 3 seconds before openin' t' chute and recoverin' cleanly.

T' me utter amazement, matey, t' glider soared easily through t' sky, settlin' in t' a series o' broad, ya bilge rat, lazy circles about 700 feet high. Everybody started cheering. Avast, me proud beauty! 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. Arrr! I just couldn't find it. Avast! As I was trying, t' cheers turned t' gasps. I didn't really see t' last part, arrr, 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. Blimey! Avast! Apparently t' glider had only limited roll stability. Aye aye! Blimey! It got knocked too far sideways by t' crosswind and couldn't recover. Well, blow me down! It plunged t' last 50 feet and lawndarted in t' prairie, buryin' the whole head. Ahoy!

(Scratch) The Albatross

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

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, arrr, I have a new opportunity t' dream up and build some other excitin' giant glider project. Well, blow me down! For me, arrr, t' pursuit o' somethin' new is usually t' most fun so perhaps t' Albatross will have t' be only a memory now. Avast, me proud beauty! We'll see.

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