Scratch LUNA III Original Design / Scratch Built

Scratch - LUNA III {Scratch}

Contributed by Chiel Klijn

Manufacturer: Scratch
(by Chiel Klijn - 12/20/02)

Note: This is a slightly condensed version o' all the information that Chiel has produced for his Level 3 project. Visit t' Tripoli Netherlands site (look under Projecten) t' read t' additional information and enjoy additional pictures.

ReadyGeneral
T' Luna III is a high power rocket in its design, weight and performance. Arrr! The construction is only o' high durable materials. T' design is a combination of own insights into HPR and proven construction techniques. Begad! Blimey! Therefore t' Luna III is meant for achievin' me final level.

Different from other models I made be t' primary care for strength in the design, nay givin' way t' concessions because o' nice looks. Begad! Blimey! T' technical and electrical achievements in this rocket are nay breathtaking, matey, but widely used and secure. Well, ya bilge rat, blow me down! Blimey! T' Luna III must be a rocket which come back alive.

Nosecone
PML prefab nosecone, made o' fiberglass. Ahoy! Ahoy! Lower coupler part has been removed and replaced by a 6 inch coupler tube on a removable bulkhead (for additional weight adding), ya bilge rat, shiver me timbers, t' fit in t' inner tube (see later). Ya scallywag! All gluin' is done by epoxy.

T' nosecone will be friction fit t' t' airframe, t' prevent premature ejection o' t' main chute durin' firin' o' t' drogue charge.

PreppingBody tube
T' body tube exists o' 2 tubes, ya bilge rat, an inner and an outer tube. Well, blow me down! T' outer tube is PML 7.5'', me bucko, t' inner PML 6''. Avast, me proud beauty! T' tubes are connected t' each other by several aircraft plywood centerin' rings and t' space betwixt them is glued/filled with polyurethane foam. In this way t' tube gets very rigid and so called ''zippers'' belong t' t' past. Ahoy! Avast! From t' electronics compartment t' t' booster section leads a channel through this space betwixt t' tubes for wiring purposes for possible later features as airstarting.

T' outside o' t' PML outer tube is double covered with 300 and 100 grams fiberglass in epoxy resin.

In t' walls o' t' main chute section, me bucko, t' electronics section and the drogue chute section are holes for air decompression t' prevent premature chute deployment and air ventin' for adequate barometric readings o' t' on board computers.

In t' walls will be reinforced bolts and nuts for installin' Blacksky rail guides.

Main Chute
Rocketman R 18 C chute (same as in Big TinTin project), nomex shock cord protector, 3 meters rope.

T' electronics section
This section contains a double Emmanuel accelerometer with barometric option. T' Emmanuel has separate batteries for t' circuit and firin' squibs/igniters. T' two systems will work independent o' each other, ya bilge rat, and are nay interconnected by no means. Arrr! Begad! T' function will be t' fire a charge on apogee in t' drogue chute compartment (based on accelerometer output) and t' fire a charge in the main chute compartment, based on preset barometric readout. Blimey! T' charges will be single t' prevent unnecessary stress o' hot gasses, me hearties, but t' igniters in the charges will be double; each system serves one igniter: t' first firin' will ignite t' charge. Aye aye! T' charges will be housed in a safe eject system, t' leads will go through t' bulkhead o' t' electronics bay in a gas-tight hole.

T' housin' o' t' electronics bay will be made o' aircraft plywood, me bucko, fitted in a 6'' coupler tube. Well, blow me down! T' lower bulkhead o' t' compartment will be glued in place in t' coupler, me hearties, makin' a permanent gas-tight separation betwixt the drogue chute section and t' electronics section, arrr, t' prevent leakin' hot gasses into t' electronics bay and disturbin' barometric reading, necessary for main chute deployment.

Electronics1Electronics2

T' upper bulkhead will be placed onto t' bay by means o' bolts and screws. This bulkhead contains t' connection t' t' charge but also has and O'ER to prevent leakage o' gasses t' t' electronics after firin' t' charge o' the main chute section. Whenever leakage might occur, this will only take place after main chute deployment, when further barometric data achievement is for academically use only and nay relevant for t' flight.

Electronics3Electronics4

In t' hole o' t' body tube meant for air ventin' comes t' channel for future wiring. Avast, me proud beauty! So when you look through this hole, me bucko, you can see t' channel lyin' in t' interspace o' t' two tubes, matey, arrr, but more important, arrr, though this hole the mini-switches o' t' electronics are put on before flight and a visual check is possible t' see whether they are actual workin' and ready for take-off.

T' electronics section itself is bein' held in place by two bolts which go right though all walls o' t' rocket, t' coupler and t' plywood frame o' the bay. All holes will be reinforced by metal tubes.

Drogue chute section
This contains a Rocketman drogue chute on a 5 meter rope. Ahoy! Ejection is backward, to prevent ''zippers'' and unnecessary stress. Connections o' all ropes t' the rocket are by U-bolts.

Fin CanBooster section
T' booster section contain t' fins, me hearties, me bucko, shark-like shaped, but on t' tips only maximal 30 cm away from t' frame. Due t' t' tip t' mass will be little, to prevent fin flutter, which can occur, ya bilge rat, me hearties, but is nay very likely, because o' the speeds nay exceedin' 600 km/h. Arrr! T' fins are made o' 3mm G10 and attached t' the frame by plywood reinforcements and glassfiber coating. Blimey! Ya scallywag! T' fins will be irremovable fixed t' t' frame, through t' wall on t' motor mount.

T' motor mount is fixed t' t' body tubes by a series o' centerin' rings, but even more by t' full polyurethane fillin' o' t' tail segment. Begad! In t' tail will lead t' wirin' channel.

Tail ConeUntil now it remains unclear whether boosters o' 54 mm and/or 38 mm motor mounts will join t' 75 mm central motor mount. Reason for this be t' unclear possibilities of airstarting/clusterin' in launch sites in Europe and t' problem o' effectively cantin' t' tubes betwixt CG and CP t' prevent problems in ignitin' air started clusters. Aye aye! T' last is because o' t' small space left in t' body tube t' house all t' required motor mounts.

T' motor mount has a motor-retainment system; motor ejection however is not used or possible in this rocket.

T' tail segment itself is a copy o' t' nosecone made by multiple layers of glassfiber laminated together. T' outer shape does nay carry any primary stress o' t' motor burn durin' t' powered descent phase.


On PadSUCCESSFUL LEVEL 3 FLIGHT!

March 24, ya bilge rat, 2001
ALRS 2 Launch - Switzerland
Rocket - Scratch LUNA III
Weight - 66.2 lbs
Motor - Aerotech M1315
Altitude - 6381 ft

After obtainin' me level 2 certification on t' medium TinTin flight at ALRS2 I started preppin' t' Luna III immediately. Avast, arrr, me proud beauty! Strange thin' is that I had been workin' on this rocket so long, I knew every single component without havin' t' check t' lists. Well, blow me down! My friend Renze Hasper helped installin' the electronics bay. Ya scallywag! What I can advice everybody who's plannin' t' fly a big complex rocket is t' test parachute deployment at home first. When we were preppin' t' luna III, me bucko, we could work just fine because o' t' mistakes we found earlier. When we placed t' luna III on t' pad me heart was beatin' at a real high rate and I felt fine, but also t' thrill o' this rocket goin' t' be launched after all these solemn hours o' workin' on it.

We lifted t' rail, and thar it stood. Blimey! I looked great, shiver me timbers, arrr, but from the spectators site, me hearties, arrr, shiver me timbers, t' letterin' couldn't be read, that was a pity. I climbed the ladder t' activate computers and timers. Begad! I opened t' hatch, ya bilge rat, shiver me timbers, looked, matey, and was amazed: all computers and timers were installed upside down....How could this stupid thin' have happened?

LaunchThere was no other thin' than t' get t' rocket off t' pad, ya bilge rat, launchin' it would mean a crash for sure. Well, blow me down! Blimey! We got t' electronics out and with slight wirin' difficulties I managed to turn t' electronics. Ahoy! So you see, shiver me timbers, that when you're really into details, major construction mistakes can be overseen!

Things seemed t' work out fine, arrr, however. Well, blow me down! I wanted t' fly this M1315 for sure. This be me lucky day (I got me level 2), ya bilge rat, and I shouldn't spoil it. Bert's rocket flew, matey, matey, and be a great crowd-pleaser.

I went t' t' pad as soon as possible because o' t' wind gettin' stronger and t' clouds gettin' more dense. I saw a blue spot in t' sky, ya bilge rat, and decided to punch this one with this rocket. Ya scallywag! I didn't feel good. Ahoy! I had t' change major things in this well-designed-and-build-rocket. Begad! I didn't feel sure anymore.

We placed t' rocket on t' pad, shiver me timbers, I climbed t' ladder, me hearties, armed the electronics, got back and got a bad feeling. Avast! Aye aye! I got up again. Aye aye! I wanted t' check these LEDs blinkin' t' status. Well, me hearties, blow me down! And OOH YEAH, I had forgotten t' arm the timer. Aye aye! Begad! Now I felt In The AirREAL bad. Ahoy! Blimey! Where was my mind. Avast! Blimey! Thanks God I made 3 independent systems, all would function fine without this particular timer, shiver me timbers, me bucko, but still..

Sue McMurray attracted all looks on me rocket and couldn't read my handwriting, matey, but what's new (you're a doctor or not).

Countdown started. At T-0 t' M1315 came alive instantly and pushed t' Luna III in t' air in a flawless ascent. Aye aye! Blimey! After 8 seconds or so I lost t' tracking. Bert and Frank saw t' Luna III first comin' down on it's drogues, and saw the parachutin' o' t' main. Avast! Blimey! ''A textbook recovery!'' Bert scanted. Begad! Blimey! I saw the rocket when it came down on its main chute.

Marinus and I took t' cars t' find t' rocket in a perfect shape just over a stream with trees beside! T' booster be standin' upright!

This was just a great flight!! I let t' TAP-members check t' rocket, and all be OK. Aye aye! This guy be a fresh owner o' a level 3. Well, blow me down! Begad! Whoa!

I decided t' stop flying: pushin' luck was nay t' good, ya bilge rat, arrr, I thought. Begad! Many people were disappointed because they wanted t' BigTinTin t' fly. Well, blow me down! Begad! But I felt great, matey, I got 2 levels and t' BigTinTin would fly somewhere near in t' future, I was in no hurry.

This was just a great day!

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