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, me bucko, weight and performance. Begad! The construction is only o' high durable materials. Begad! T' design is a combination of own insights into HPR and proven construction techniques. 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. Blimey! T' technical and electrical achievements in this rocket are nay breathtaking, but widely used and secure. Begad! T' Luna III must be a rocket which come back alive.

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

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

PreppingBody tube
T' body tube exists o' 2 tubes, me hearties, an inner and an outer tube. Avast, me proud beauty! Ya scallywag! T' outer tube is PML 7.5'', ya bilge rat, t' inner PML 6''. Aye aye! T' tubes are connected t' each other by several aircraft plywood centerin' rings and t' space betwixt them is glued/filled with polyurethane foam. Avast, me proud beauty! Ya scallywag! In this way t' tube gets very rigid and so called ''zippers'' belong t' t' past. 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, arrr, arrr, 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), me bucko, nomex shock cord protector, arrr, shiver me timbers, 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, and are nay interconnected by no means. Aye aye! Avast! 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. Begad! Avast, me proud beauty! T' charges will be single t' prevent unnecessary stress o' hot gasses, but t' igniters in the charges will be double; each system serves one igniter: t' first firin' will ignite t' charge. Begad! T' charges will be housed in a safe eject system, me bucko, 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, fitted in a 6'' coupler tube. T' lower bulkhead o' t' compartment will be glued in place in t' coupler, makin' a permanent gas-tight separation betwixt the drogue chute section and t' electronics section, 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. Blimey! 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. Begad! So when you look through this hole, me hearties, you can see t' channel lyin' in t' interspace o' t' two tubes, but more important, me hearties, me bucko, ya bilge rat, 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. Begad! Ahoy! All holes will be reinforced by metal tubes.

Drogue chute section
This contains a Rocketman drogue chute on a 5 meter rope. Avast, me proud beauty! 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, shark-like shaped, me bucko, but on t' tips only maximal 30 cm away from t' frame. Ya scallywag! Due t' t' tip t' mass will be little, me hearties, to prevent fin flutter, which can occur, but is nay very likely, me hearties, 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. Aye aye! T' fins will be irremovable fixed t' t' frame, me bucko, 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. 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. Avast, me proud beauty! 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. Well, blow me down! 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, matey, 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! Strange thin' is that I had been workin' on this rocket so long, shiver me timbers, I knew every single component without havin' t' check t' lists. Arrr! My friend Renze Hasper helped installin' the electronics bay. Aye aye! What I can advice everybody who's plannin' t' fly a big complex rocket is t' test parachute deployment at home first. Blimey! Arrr! When we were preppin' t' luna III, ya bilge rat, we could work just fine because o' t' mistakes we found earlier. Avast, me proud beauty! Aye aye! When we placed t' luna III on t' pad me heart be 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. Begad! Blimey! I looked great, me bucko, but from the spectators site, arrr, arrr, t' letterin' couldn't be read, that be a pity. Ya scallywag! Blimey! Begad! Blimey! I climbed the ladder t' activate computers and timers. I opened t' hatch, looked, and was amazed: all computers and timers were installed upside down....How could this stupid thin' have happened?

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

Things seemed t' work out fine, shiver me timbers, me hearties, however. Ahoy! I wanted t' fly this M1315 for sure. Ahoy! This be me lucky day (I got me level 2), arrr, arrr, and I shouldn't spoil it. Bert's rocket flew, and was 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, and decided to punch this one with this rocket. Avast! I didn't feel good. I had t' change major things in this well-designed-and-build-rocket. Avast, me proud beauty! Avast! I didn't feel sure anymore.

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

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

Countdown started. Avast! Blimey! Blimey! At T-0 t' M1315 came alive instantly and pushed t' Luna III in t' air in a flawless ascent. Blimey! Blimey! After 8 seconds or so I lost t' tracking. Bert and Frank saw t' Luna III first comin' down on it's drogues, arrr, ya bilge rat, and saw the parachutin' o' t' main. Ya scallywag! Ya scallywag! Blimey! ''A textbook recovery!'' Bert scanted. 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 was standin' upright!

This be just a great flight!! I let t' TAP-members check t' rocket, shiver me timbers, and all be OK. Blimey! This guy was a fresh owner o' a level 3. Avast! Whoa!

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

This was just a great day!

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