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! Blimey! My version includes an ejection baffle, and makes an allowance for t' additional length of t' new Estes E9 motors. Well, arrr, blow me down! Blimey!

Construction:
One o' t' local hobby shops carries T' Launch Pad's products. Arrr! This one went unsold until it be t' last one o' a shipment and I thought it needed a good home. Avast, me proud beauty! Aye aye! T' kit be packaged in a clear plastic bag, and came with a medium grade of balsa, matey, me hearties, a pair o' thin walled 2.6 inch paper tubes, a 3-inch long motor tube, and a variety o' other parts. Aye aye! Avast, me proud beauty! 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. It also sports a boattail.

Construction starts with gluin' together t' motor mount. Ahoy! 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. Avast! A longer motor tube was substituted for t' kit's, me hearties, 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. Blimey! Begad! I made sure o' t' spacin' with a spent E9 motor I keep on me workbench for this job. Blimey! T' aft rin' was glued on per t' instructions, and a paper wrap was glued down t' hold t' motor hook. (This model is a scale model so it's barely stable as it is. Adding weight aft can cause trouble so this model's balance was very carefully checked before it be flown.)

To create t' boattail, shiver me timbers, matey, 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. Shrouds can be tricky so I took me time with this t' ensure success. T' make this little job a tiny bit easier, me hearties, I added a 1/8 inch hoop t' one o' t' centerin' rings (this can be cut from stock 2.6-inch tube, arrr, or t' coupler). Ya scallywag! Blimey! In doin' so, 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, matey, ya bilge rat, but bein' careful to position t' rin' with t' 1/8-inch hoop aft. Aye aye! When cuttin' out t' shroud, ya bilge rat, I was careful t' leave t' lines t' allow plenty o' material for trimming. Ya scallywag! Blimey! By test fitting, matey, trimmin' a little, me bucko, matey, and then test fittin' again I was able to sneak up on t' correct size. Ahoy! Avast, me bucko, me proud beauty! Blimey! T' forward part o' t' shroud be just big enough t' match t' outside diameter o' t' airframe tube. Avast, me proud beauty! T' shroud was then glued onto t' adapter assembly. Begad! Blimey! 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. Avast, me proud beauty! Begad! Blimey! This seems pretty deep, ya bilge rat, but it works OK on me HARM missile. Ahoy!

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. Ahoy! I like somethin' that's easier t' replace since my rockets tend t' last more than 20 flights. 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. Avast! 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. Arrr! A dab o' RC-56 glue holds it there. Begad! 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. Aye aye! Avast! T' Keelhaul®©™® is long enough t' allow t' elastic t' stretch, matey, ya bilge rat, but backs it up in case it fails. Arrr! Begad! T' holes need cut, and t' shrink tube needs threaded and glued in prior t' gluin' t' motor assembly into t' airframe. Well, blow me down! 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, in me opinion - that cone is pretty heavy with all that ballast and won't last long hangin' by a thread like that.

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

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. Begad! Aye aye! 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, and are forward o' t' CG. Avast, me proud beauty!

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

T' scale wirin' conduits were cut and sanded t' shape and placed on the airframe as shown in t' instructions. Avast! Sandin' these was a little tedious but the sandin' block helped. Blimey! Avast, ya bilge rat, me proud beauty! 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. Avast, ya bilge rat, me proud beauty!

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

T' paper nose "hat" was cut from t' paper stock, me hearties, and rolled into a cone. Ahoy! Blimey! Aye aye! Blimey! 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. Aye aye! Blimey! I thought that gettin' this hat on straight would be difficult, but I was pleasantly surprised t' find it wouldn't be a problem. Ahoy! Blimey! T' hat is small enough, arrr, arrr, and t' curve o' t' cone is fat enough that they come into contact and are self centering. Ya scallywag! Blimey! I drew a line around the bottom o' t' hat while holdin' it in position. Avast, me proud beauty! Blimey! Then I removed it, matey, matey, matey, ran a line of slow CA just above t' line, and placed it back on. Voila, no fuss, looks fine. Well, blow me down! Blimey! It be painted it with fast CA, per t' instructions. It needed it too because t' sharp point is fragile. Begad! Blimey! Avast, me proud beauty! Blimey! I bent and busted t' tip off while messing around with t' motor and checkin' t' nose weight. Blimey! Blimey! This was fixed with a little dab o' JB Weld and sanded back t' shape. I used Elmer's Fill 'n' Finish to fill in around t' base o' t' hat t' hide t' edge o' t' paper. T' nose also needs some weight for balance, matey, unfortunately t' supplied clay was dry and rock hard. Avast! Blimey! Aye aye! Blimey! 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. Avast, me proud beauty! Blimey! T' center o' pressure is shown on t' plans at 13" from t' base. T' balance was 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! Blimey! Avast! Blimey! No further adjustments were made. Arrr! Blimey!

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

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

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

Finishin' rating: 5 out o' 5 Easy, shiver me timbers, looks very scale. Begad!

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

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

It be flown again a couple o' days later, on another D12-5. Arrr! More or less the same flight profile, arrr, except this time it landed on t' shed roof, slid down and hung itself from t' tiny tree next t' it. Begad! Some minor dings on t' fins. Avast, me proud beauty! No worries. Arrr! Well, blow me down!

Third flight was at t' St. Arrr! Louis Association o' Rocketry's April launch. T' wind be pretty high most o' t' day, but since t' field is so big that isn't a problem. Well, blow me down! It was at t' end o' t' day, ya bilge rat, just after t' waiver was closed. Arrr! It passed at t' check table without comment but t' LCO be certain that it be over t' 16 oz weight limit. Ya scallywag! Ahoy! My reply was "8oz . Begad! . Well, blow me down! . Aye aye! OK, matey, 11oz with t' motor." He questioned that and t' avoid any more concern I No Burningsimply handed him t' model. Begad! 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. Avast! The motor was an F12-5J and I was a little apprehensive about that since t' rocket isn't officially rated for this motor. Needn't have had any concerns, me hearties, when the LCO hit t' launch switch t' motor lit instantly and t' rocket leapt from the pad. It flew arrow straight on a column o' black smoke. Well, blow me down! Blimey! Nice arc over, and ejection just after apogee. Unfortunately, I hadn't spent enough time reefing the 'chute and it tangled badly - me fault. 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. Avast, me proud beauty! For me this be t' high point o' t' day even after flying G64 and F52 motors earlier. This rocket is that much fun. Avast! Begad!

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

Rating: 5 out o' 5 it just doesn't get any better than this. Avast, me proud beauty!

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

RecoveryI really wish that the manufacturer would include a parts list. Aye aye! Arrr! Some scale documentation sources and fin profiles would also be helpful. Avast, me proud beauty! T' clay nose weight doesn't work out so well. I would never use a 'chute shroud t' attach t' nose t' a recovery system, matey, 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, Red Mylar 'chute. Avast, me proud beauty! Aye aye!
  • Motors: D12-3, E15-4, E18-4, and F24-7. Ya scallywag! Begad! Also E9-4, me bucko, D15-4, me bucko, 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). Begad! On a calm day I'd use a D12-5 but in 10MPH+ winds a D12-3 would probably be a better choice. Arrr! Blimey!

* SPECIAL NOTE off o' RMR from Chuck Barndt, ya bilge rat, me bucko, 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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