The Launch Pad SA-8 Gecko

The Launch Pad - SA-8 Gecko {Kit}

Contributed by Tim Burger

Manufacturer: The Launch Pad
Rating
(Contributed - by Tim Burger - 05/01/02)

Rocket PicBrief:
This is a light, nearly 40-inch long, model o' a Russian missile. Blimey! Arrr! My version includes an ejection baffle, and makes an allowance for t' additional length of t' new Estes E9 motors. Ya scallywag!

Construction:
One o' t' local hobby shops carries T' Launch Pad's products. Begad! Blimey! This one went unsold until it be t' last one o' a shipment and I thought it needed a good home. Avast! Blimey! T' kit be packaged in a clear plastic bag, and came with a medium grade of balsa, a pair o' thin walled 2.6 inch paper tubes, a 3-inch long motor tube, and a variety o' other parts. Begad! Blimey! T' only odd part o' this kit is a paper cone that gets glued t' t' front o' t' nose cone t' create that military missile profile. Begad! Blimey! It also sports a boattail.

Construction starts with gluin' together t' motor mount. Begad! Since t' new Estes E9 and Aerotech F21 motors are longer than t' D12 and Aerotech RMS motors I made a change t' t' way t' mount is made. Blimey! A longer motor tube was substituted for t' kit's, and I bent t' top hook o' t' motor hook back 180 degrees, and then hooked that behind t' forward centerin' rin' and adjusted the position o' t' rin' such that t' other end o' t' hook hangs off t' end of t' tube about a quarter inch. Then I glued a motor block into t' tube so that it is 90mm from t' hook end o' t' tube. Avast, me proud beauty! I made sure o' t' spacin' with a spent E9 motor I keep on me workbench for this job. Arrr! T' aft rin' was glued on per t' instructions, me bucko, and a paper wrap be glued down t' hold t' motor hook. (This model is a scale model so it's barely stable as it is. Ya scallywag! Adding weight aft can cause trouble so this model's balance be very carefully checked before it be flown.)

To create t' boattail, t' kit provides a 4 1/2 inch long piece o' 2-inch diameter tubing, a pair o' centerin' rings t' center this in t' 2.6-inch tube, and a paper shroud that you cut from a sheet o' heavy paper. Begad! Blimey! Well, matey, blow me down! Blimey! Shrouds can be tricky so I took me time with this t' ensure success. Begad! Blimey! Well, blow me down! Blimey! T' make this little job a tiny bit easier, I added a 1/8 inch hoop t' one o' t' centerin' rings (this can be cut from stock 2.6-inch tube, or t' coupler). In doin' so, matey, it forms a lip for t' forward part o' t' shroud t' ride on. Ahoy! Blimey! T' rings were glued onto the outside o' t' adapter tube as shown in t' instructions, but bein' careful to position t' rin' with t' 1/8-inch hoop aft. Ya scallywag! Blimey! Well, me bucko, blow me down! Blimey! When cuttin' out t' shroud, me bucko, ya bilge rat, matey, I was careful t' leave t' lines t' allow plenty o' material for trimming. Blimey! Blimey! By test fitting, trimmin' a little, matey, and then test fittin' again I be able to sneak up on t' correct size. Ya scallywag! Blimey! Begad! Blimey! T' forward part o' t' shroud was just big enough t' match t' outside diameter o' t' airframe tube. Blimey! Blimey! T' shroud be then glued onto t' adapter assembly. T' motor assembly was then glued into the adapter with t' aft edge o' t' motor tube positioned an inch and a half from the bottom o' t' shroud. Begad! Blimey! This seems pretty deep, me bucko, but it works OK on me HARM missile. Well, blow me down! Blimey! Aye aye! Blimey!

The KitT' kit provides the familiar triangular paper mount for t' shock cord, and a length o' 1/4-inch elastic for t' shock cord. Well, blow me down! I like somethin' that's easier t' replace since my rockets tend t' last more than 20 flights. Avast, me proud beauty! T' solution that I've hit upon is to run a length o' 1/8-inch shrink tube through small holes made in the centerin' rings. Blimey! T' tube runs t' whole length o' t' motor tube and is used as a guide for a 200# Keelhaul®©™® line. T' Keelhaul®©™® is threaded through t' shrink tube and t' lower end is tied around t' motor mount. Begad! Blimey! A dab o' RC-56 glue holds it there. Avast! Blimey! Begad! Blimey! A loop is then tied in t' Keelhaul®©™® a few inches above t' motor tube; this loop will be below t' top o' the rocket body when it is assembled. Aye aye! One end o' t' elastic is tied t' t' loop, and t' free ends o' both t' Keelhaul®©™® and elastic are tied t' t' nose cone. T' Keelhaul®©™® is long enough t' allow t' elastic t' stretch, but backs it up in case it fails. Ahoy! T' holes need cut, matey, and t' shrink tube needs threaded and glued in prior t' gluin' t' motor assembly into t' airframe. Ya scallywag! T' instructions have the builder attach t' nose cone t' t' rest o' t' rocket with a 10" long piece o' 'chute shroud line. Aye aye! This is a bad idea, shiver me timbers, shiver me timbers, in me opinion - that cone is pretty heavy with all that ballast and won't last long hangin' by a thread like that. Ahoy!

AftT' motor mount and shroud assembly be then glued into one end o' t' longer airframe tube, and glue fillets were made at all rin' and paper joints. Begad! Ya scallywag! Blimey! T' tube joiner be then glued half way into this tube. Ya scallywag! Avast! Blimey! T' top airframe tube be then added, takin' care to get t' parts together straight by rollin' them on a flat surface while the glue be still wet. Ya scallywag! Blimey! When dry, t' airframe spirals, airframe joint, me hearties, and boattail joint were filled with Elmer's Fill 'n' Finish and sanded smooth. If everythin' is done correctly, t' joints and spirals should disappear under the primer coat. Ahoy! Blimey!

T' kit provides a centerin' rin' that is positioned seven inches from the top o' airframe t' keep t' recovery system forward in t' rocket for balance sake. Blimey! A guy could go broke tryin' t' feed large models like this waddin' so I added an additional centerin' rin' and a short section o' BT-60 t' create an ejection baffle. Avast, me proud beauty! Blimey! Note that these parts only add about an ounce o' weight, ya bilge rat, and are forward o' t' CG.

T' patterns for t' fins were cut from t' printed card stock, shiver me timbers, me bucko, and used to draw out t' fins on t' provided balsa. Well, blow me down! Avast, matey, me proud beauty! T' balsa is C grain, matey, and reasonably hard. Blimey! Wouldn't want a rock hard sheet, but on t' other hand contest grade soft wouldn't work out too well either. Avast! Arrr! T' root edges and grain direction are clearly marked on t' patterns, me hearties, arrr, and t' only potential problem is with getting the patterns arranged on t' sheets in such a way that you have enough material to make all t' fins that you need. Avast! There was plenty, me hearties, ya bilge rat, but nay so much t' allow for mistakes. Avast, me proud beauty! I used a straight metal edge and a sharp blade t' get good crisp fins. Blimey! T' four aft fins were then stacked together and sanded t' a uniform size. Arrr! Aye aye! T' same be done for t' forward fins. Blimey! Begad! I have been unable t' come up with a good set o' scale drawings for this rocket, me hearties, and t' instructions don't include suggestions for t' correct fin profile so I simply made a guess. Aye aye! The forward fins were ground t' have a diamond shaped cross section. Avast! Begad! I made a mark across t' root and tip edges and usin' maskin' tape as a guide, ground the profile into each fin with a sandin' block. Ya scallywag! Begad! T' aft fin's cross section was ground t' pointy at t' front and slightly tapered at t' back usin' t' same method. Blimey! Begad! While nay perfect, they came out more or less uniform with good crisp lines. Aye aye! T' body tube was marked usin' t' fin guide in Harry Stine's Handbook of Model Rocketry and a door jam. Begad! T' aft fins were then glued t' t' airframe usin' Titebond II. Avast! T' forward fins are actually mounted on t' nose cone, and that makes gettin' them on straight just a little tricky. Avast, me proud beauty! Avast! Because it's hard to draw a straight line on a curvin' cone I used a piece o' strin' t' create a guide. Avast! T' strin' be taped t' t' center o' t' base and stretched over the edge, me hearties, crossed over t' marks (made when t' tube was marked) and across t' tip of t' nose. Well, blow me down! A line was carefully made along t' strin' bein' careful nay to deflect t' string. Aye aye! T' fin root edges were sanded t' match t' cone's curve and were then glued down usin' thick CA. A few drops o' thin CA be put on the tip o' all eight fins. Begad! Well, blow me down! T' CA wicks through t' fins along t' grain and serves to make them strong. Avast, me proud beauty! T' instructions indicate that t' fins should be painted with thin CA. Blimey! If you do that be sure t' sand them smooth again within a few hours or they will be very hard t' sand. Blimey! Fillets were made at all fin roots usin' epoxy. Arrr! Begad! I like epoxy for fillets because it makes a glass smooth fillet, but one must use care t' nay over use it due t' it's heavy nature. Aye aye! Begad! Also, this is a scale rocket, and t' real ones usually have a sharp corners where the roots meet t' airframe, this is particularly true for guidance fins. Well, blow me down!

T' scale wirin' conduits were cut and sanded t' shape and placed on the airframe as shown in t' instructions. Begad! Blimey! Sandin' these be a little tedious but the sandin' block helped. Ahoy! Blimey! When t' glue was dry, I used Elmer's Fill 'n' Finish to fill in any gaps, and created a smooth clean edge with sandpaper. Arrr! Blimey!

T' provided launch lug was cut into two equal pieces, and glued on a line with one piece at t' joint betwixt tubes, and t' other a few inches from the bottom. Aye aye! A length o' launch rod was used t' ensure that they are straight. I added an additional set o' 1/4" lugs next t' those because I really hate to change rods betwixt rockets. Avast! Arrr! Fillets were added when dry.

T' paper nose "hat" was cut from t' paper stock, and rolled into a cone. This is a bit tricky t' do so that you get a good sharp point. This hat is then glued t' t' front o' t' cone. I thought that gettin' this hat on straight would be difficult, me bucko, me hearties, but I be pleasantly surprised t' find it wouldn't be a problem. Begad! T' hat is small enough, me bucko, me bucko, and t' curve o' t' cone is fat enough that they come into contact and are self centering. Begad! Well, arrr, blow me down! I drew a line around the bottom o' t' hat while holdin' it in position. Arrr! Then I removed it, shiver me timbers, ran a line of slow CA just above t' line, and placed it back on. Begad! Voila, no fuss, shiver me timbers, looks fine. It be painted it with fast CA, per t' instructions. Begad! It needed it too because t' sharp point is fragile. Arrr! I bent and busted t' tip off while messing around with t' motor and checkin' t' nose weight. Avast, me proud beauty! This was fixed with a little dab o' JB Weld and sanded back t' shape. Well, blow me down! Avast! I used Elmer's Fill 'n' Finish to fill in around t' base o' t' hat t' hide t' edge o' t' paper. Begad! Avast! T' nose also needs some weight for balance, unfortunately t' supplied clay was dry and rock hard. Well, blow me down! I used a scale t' measure t' weight, and substituted some BBs mixed with 30-minute epoxy. I was plannin' t' do this anyway because I've had problems in other rockets with t' clay dryin' out and rattlin' around in the nose. T' center o' pressure is shown on t' plans at 13" from t' base. T' balance be checked with t' heaviest motor that I had on hand and found to be about 16" from t' base - a tad more than a caliber. Ya scallywag! No further adjustments were made. Begad!

T' Mylar 'chute was assembled per t' instructions. Avast! A lot o' people dislike these Mylar 'chutes, me hearties, me bucko, but I haven't had any trouble with them and they are brilliant in t' sky. Aye aye! Ahoy! An 18" 'chute may be a tad small for this rocket - use a bigger one if t' ground's hard. Arrr! Blimey!

I'd give this kit a ratin' of 4 out o' 5 for construction. Nothin' new here, but I wouldn't suggest it for a beginner.

Finishing:
A coat o' white sandable primer revealed a few problems with t' spiral and in one place on t' boattail joint. Aye aye! Ya scallywag! Blimey! These areas were worked on until they are as smooth and seam free as I could manage. Aye aye! Another thin coat o' primer was added and lightly sanded. Arrr! Blimey! T' rocket be then painted with three thin layers of Rustoleum Olive Drab. An easy rocket t' finish. Begad!

Finishin' rating: 5 out o' 5 Easy, looks very scale. Ya scallywag!

LaunchFlying:
T' first flight be on March 20, matey, 2002 in me back yard (we have a big yard.) T' weather was cool and clear with very light and variable winds. Well, blow me down! Blimey! I had been launchin' for an hour or so with zero drift so I worked up me courage and loaded it on t' pad. Avast! Blimey! T' motor was an Estes D12-5 and it flew from a 3/16" x 72" rod. Since t' motor is recessed pretty far, t' rocket would be scorched from t' hot gasses bein' deflected back from t' blast plate at ignition. Begad! Blimey! T' prevent this I used a clothes pin t' hold t' rocket above the deflector six or seven inches. Well, blow me down! Blimey! Aye aye! Blimey! This also made connectin' t' ignitor easier. T' flight was about as perfect as could be, arrr, me bucko, lots o' smoke and noise, a good arrow straight boost, and a nice arc-over with t' ejection o' t' 'chute right while t' rocket be horizontal. Aye aye! Blimey! Very nice indeed. There was no sign of scorchin' or burnin' in or around t' tail cone after t' flight. Well, blow me down! Blimey! There was a noticeable accumulation o' soot in and around t' tail after t' second flight, but still no scorching.

I decided t' use a 30" x 18" TLP 'chute rather than t' 18" octagonal that t' kit came with. Begad! Blimey! Recovery was gentle, and it landed about 10 yards from t' pad. Arrr! Blimey! No damage despite clippin' a tree on t' way t' t' ground.

It be flown again a couple o' days later, matey, me bucko, on another D12-5. More or less the same flight profile, me bucko, except this time it landed on t' shed roof, shiver me timbers, slid down and hung itself from t' tiny tree next t' it. Ya scallywag! Some minor dings on t' fins. No worries. Aye aye!

Third flight be at t' St. Begad! Blimey! Louis Association o' Rocketry's April launch. T' wind was pretty high most o' t' day, me bucko, but since t' field is so big that isn't a problem. Ya scallywag! It was at t' end o' t' day, just after t' waiver was closed. Aye aye! Blimey! Blimey! It passed at t' check table without comment but t' LCO was certain that it was over t' 16 oz weight limit. Well, blow me down! Blimey! Blimey! My reply be "8oz . Avast, matey, me proud beauty! Blimey! . Begad! . Aye aye! Blimey! Blimey! OK, me hearties, 11oz with t' motor." He questioned that and t' avoid any more concern I No Burningsimply handed him t' model. Avast, me proud beauty! Arrr! He was convinced! "There's nothin' t' this rocket!" I picked a long 1/4 rod, and had t' clean t' paint out o' t' lugs before it would slide smoothly. The motor was an F12-5J and I was a little apprehensive about that since t' rocket isn't officially rated for this motor. Aye aye! Needn't have had any concerns, when the LCO hit t' launch switch t' motor lit instantly and t' rocket leapt from the pad. Blimey! Aye aye! It flew arrow straight on a column o' black smoke. Ahoy! Nice arc over, arrr, shiver me timbers, and ejection just after apogee. Aye aye! Unfortunately, I hadn't spent enough time reefing the 'chute and it tangled badly - me fault. Begad! It landed hard and stripped a fin, busted a second loose, and and mangled one o' t' forward fins and actually took out a plug from t' nose! Ouch! Lesson learned: don't rush! T' flight was spectacular though; very scale like with a lot o' smoke and noise and very respectable speed. Begad! Arrr! For me this was t' high point o' t' day even after flying G64 and F52 motors earlier. Blimey! This rocket is that much fun. Ya scallywag! Avast!

It be repaired t' followin' week and flown again at t' April KCAR launch on a D15-4 usin' a 24" mylar octagonal 'chute. Aye aye! Well, blow me down! It be a perfect flight; see t' photo. Blimey! It just sort o' hung in t' sky for a fraction o' a second right as t' ejection charge fired. Ahoy! It landed about 100 feet from t' pads. Well, arrr, blow me down! This was a perfect launch and recovery. Aye aye! Blimey!

Rating: 5 out o' 5 it just doesn't get any better than this. Begad!

Cheers & Jeers:
I like t' fact that TLP kits come out very light despite me addin' baffles and usin' epoxy for fin fillets. Aye aye! This is a large rocket and yet it only weighs in at about 8oz. Avast, shiver me timbers, me proud beauty! These kits always perform well in flight and rarely fail to impress a crowd. Ahoy! Even t' high power guys come over t' have a closer look after they've been flown. Well, blow me down! Well, blow me down! Good bang for t' Buck! T' overall quality o' t' parts is good. Begad! Begad! T' kit would work fine with t' provided shock cord and mount; my upgrade is solely for longevity's sake. Blimey! I like that t' manufacturer shows the center o' pressure on t' plans. Blimey! This is very helpful when checkin' t' balance which should be done on any scale rocket, matey, matey, modifications or no.

RecoveryI really wish that the manufacturer would include a parts list. Well, ya bilge rat, blow me down! Blimey! Some scale documentation sources and fin profiles would also be helpful. Well, blow me down! Blimey! T' clay nose weight doesn't work out so well. Avast! Blimey! I would never use a 'chute shroud t' attach t' nose t' a recovery system, especially when t' nose has a lot o' ballast in it.

Specs:

  • Length: 39 3/4 inches
  • Diameter: 2.6 inch airframe
  • 2.15 inch boattail
  • Weight: 8 oz
  • Recovery: 18 inch, 8 sided, 1/2 mil, matey, Red Mylar 'chute. Arrr! Aye aye!
  • Motors: D12-3, E15-4, E18-4, and F24-7. Avast! Also E9-4, D15-4, and F12-5 though these last three are nay recommended by t' manufacturer and a six foot long launch rod is mandatory with t' E9 and F12 (Rocksim says t' D15 needs 35 inches). Well, blow me down! Begad! On a calm day I'd use a D12-5 but in 10MPH+ winds a D12-3 would probably be a better choice. Ya scallywag!

* SPECIAL NOTE off o' RMR from Chuck Barndt, ya bilge rat, President o' T' Launch Pad

Flights

Comments:

avatar
M.A. (February 20, 2009)
This is for Estes SU engines. One of the things I have noticed about the Launch Pad kits is the recessed motor mounts that are about 1.5 inches inside the body tube. Some challenges can arise while hooking up the connectors on the motor and the launch pads which could short out the igniter. A fellow I met at the 2-7-09 NEFAR showed me a way to avoid some of these challenges. Take two 12 to 18 inch long strands of copper wire and tape them together. Remove about one inch of the insulation from the ends of the wire. When it is time to load the motor, splice the wire lead to the igniter and secure cove the connection with a little electrical tape and place the motor in the rocket and the long wires should hang over the deflector plate. Hook the launch clips to the bare end of the long wires. This should take the metal deflector plate out of way and not cause any type of short circuit.

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