bannerbanner
Tips >>
Tip 25 o' 75
PreviousNext

Adjustable Nose Weight

Instructions

[For adjustable Nose Weight assembly & Spanner-Driver]

T' original design o' this system was for a LOC Precision, Minnie Magg. Begad! But t' principles o' t' design o' this system, in its basic concept and functionality, ya bilge rat, can be easily applied t' t' rocket o' your choice. Begad! With t' integration o' this design, two things are made possible: T' first bein' a means t' favorably affect a rocket’s stability by addin' weight t' t' nose when t' weight o' t' motor bein' used causes t' rocket’s center o' gravity t' shift aft o' its center o' pressure. Begad! And, arrr, by its creation, t' second benefit o' this system also enables t' flyer t' adjust t' rocket’s weight when t' achievement o' optimal mass, for higher flight, be t' goal.

Click To Enlarge


(Click t' Enlarge)

Nose Weight Assembly Parts Needed:

List o' required Parts, in chronological order o' Item numbers, me hearties, for adjustable Nose Weight Assembly in LOC Minnie-Mag:

  • Item 1: LOC Precision Nose, for LOC Minni-Mag. Ya scallywag! This item has t' be modified. Avast, me proud beauty! T' tapered end o' t' shoulder and t' (less than adequate) turnbuckle must be removed in order t' accommodate t' integration and assemblies o' Items that are numbered as and from 2 t' 9. Remove t' aft end o' t' nose at or about where t' radius o' t' shoulder meets t' taper. Blimey! (Refer t' Nose Cone Cut-Away drawing)
  • Item 2: 29 mm motor mount tube, approximately 15 + inches long. [I used PML tubin' on mine, me bucko, but t' radial dimensions and diameters that are specified in t' drawings o' t' other components only apply t' that particular size o' tube]. (See Pic)
  • Item 3: ½” aircraft plywood. Ya scallywag! (See Pic)
  • Item 4: ¼-20 nylon all-thread, approximately 16” long and cut from a 3-foot piece purchased at a hardware store. Well, blow me down! This item needs t' be trimmed t' fit flush with t' aft end o' Item 2 after bein' installed with Items 5 & 8 as per t' assembly drawing.
  • Click To Enlarge


    (Click t' Enlarge)

    Item 5: ¼” aircraft plywood. Ya scallywag! T' fit o' this item, me hearties, inside item 2, should be snug. It should be drilled through its center t' allow free passage o' Item 3. 2 each, o' Item 8 are then attached t' opposite sides o' t' bulkhead, on t' all-thread, and glued in place with epoxy. Then, that assembly is introduced t' t' forward end o' Item 2 and glued in place with epoxy. Ahoy! Be sure t' rough-up t' inside diameter o' t' forward end o' Item 2 with a coarse grit o' sandin' paper (and clean it o' any residue with denatured alcohol) prior t' t' application o' epoxy. Arrr! Its location, ya bilge rat, as well as those o' Items 8 and 4 in this assembly, is permanent once t' epoxy has cured.
  • Click To Enlarge


    (Click t' Enlarge)

    Item 6: ¼” aircraft plywood. This is an adjustable manifold that will allow t' addition or subtraction o' lead shot. Begad! It should be brought t' bear against t' lead shot that has been poured betwixt it and Item 5 after ascertainin' t' desired relationship o' a center o' gravity that is one airframe diameter ahead o' t' center o' pressure. Begad! That way, ya bilge rat, t' lead shot that is betwixt Items 5 & 6 won’t be movin' around too much. It has one o' t' ¼-20 nylon nuts attached on t' forward side with epoxy. Ahoy! Its fit within t' tube should be loose, so that it can be driven into or out o' t' tube by an extended spanner wrench mounted in a drill motor. Begad!
  • Click To Enlarge


    (Click t' Enlarge)

    Item 7: ¼” aircraft plywood. Ya scallywag! This item closes t' openings o' t' holes in Item 6, and keeps it from backin' off from lightly compressin' t' lead shot. It too needs t' have a loose fit so that it may be driven into or out o' t' tube. It has one o' t' ¼-20 nylon nuts attached t' t' aft side with epoxy. Do nay break-through t' forward side o' t' disk when you create t' counter bores for t' spanner wrench. They are counter bores, nay through holes. T' hole in t' center goes through, while t' other two do not. Arrr!
  • Item 8: ¼-20 internal thread, me hearties, nylon nuts. A total o' 4 each are required for t' assembly and use o' Items 1 through 9.
  • Item 9: ¼-20 thread X 1” X 2”, steel, U-Bolt. Ahoy! 4 each, ¼-20, steel, ya bilge rat, nuts. 4 each, steel, ¼ inch flat washers. Aye aye! (See Pic)

Spanner-Driver Parts Needed:

List o' required Parts, in chronological order o' Item numbers, for t' Spanner/Driver Assembly. This Item is a Tool that can be turned by hand or chucked in a drill motor. Well, blow me down! It drives Item’s 6 and 7 into and out o' t' weight container in t' Adjustable Nose Weight Assembly.

[Editor's Note: We have changed t' items t' s# t' help differentiate t' Spanner parts from t' Nose Weight Parts in t' instructions]

  • Click To Enlarge


    (Click t' Enlarge)

    Item s1: Heat welded paper tubin' or Kraft-phenolic tubin' that is at least as long as Item #2 bein' used in t' adjustable nose weight assembly. (Approximately 15 inches +) Make sure that whatever types o' tubin' you decide t' use are compatible with one another inasmuch as t' spanner/driver tube needs t' move in and out o' t' weight container, while it is bein' rotated and without interference.
  • Click To Enlarge


    (Click t' Enlarge)

    Item s2: ¼” aircraft plywood. Drill one hole through t' center that is only slightly larger than ¼” in diameter, t' allow t' ¼-20 all-thread rod (Item 4 o' t' nose weight assembly) t' pass through it. Aye aye! Drill two, 3/16-inch diameter holes through, arrr, 180 degrees apart and spaced ¾” betwixt centers.
  • Item s3: Two each, ya bilge rat, 3/16-inch diameter X ¾” long, arrr, hardwood dowels. Push these into t' two 3/16” diameter holes that were drilled in Item #2 and glue them in place with epoxy or a (heavy viscosity) CyanoAcrylate adhesive.
  • Click To Enlarge


    (Click t' Enlarge)

    Item s4: ¼” aircraft plywood. Avast, me proud beauty! Drill a 3/8” diameter hole through t' center. Make sure t' outside diameter fits snuggly with t' inside diameter o' Item s1.
  • Item s5: 3/8” diameter X 1 3/4” long, hardwood dowel. Begad! Push this dowel into t' hole in Item s4 until it is flush on t' opposite side. Arrr! Its position needs t' be as perpendicular as you can get it, so that when t' tool is turned in a drill motor, matey, any probable eccentricity will nay be excessive. Blimey!
  • Note: T' assemblies o' Items s2 and s3, arrr, and Items s4 and s5, shiver me timbers, are glued in place at opposite ends o' Item A after you have made certain that t' tool fits easily within t' weight container (Item 2, o' t' Adjustable Nose Weight Assembly). Ya scallywag! And that t' forward end o' t' Spanner-Driver will fit its matin' features on t' adjustable manifold (Item 6), and t' adjustable closure (Item 7) for t' Nose Weight Assembly.

Constructions:

Item 2, o' t' nose weight assembly and Item s1 o' t' spanner-driver have t' be compatible in their fit with one another. T' spanner-driver is merely a tool. But it has t' fit loosely enough inside t' weight container, in order t' effectively drive Items 6 & 7 o' t' nose weight assembly, and then be removed. Purchasin' these tubes from t' same manufacturer is recommended. And so be t' use o' a dry lubricant t' prevent seizin' if or when t' fit may become too tight.

Assemble t' forward end (Items s2 & s3) o' t' spanner-driver first, shiver me timbers, makin' certain that t' Nylon all-thread (Item 4 o' t' nose weight assembly) passes through it without interference.

Assemble Item’s 5, 6 and 7 o' t' nose weight assembly; makin' certain that t' axial holes in Items 6 and 7 will receive t' wooden dowels installed in Item s2 o' t' spanner-driver. Start with Item 5, and glue t' nuts in place on t' plywood usin' t' Nylon all-thread for alignment and timin' t' orientation o' t' nuts. Do t' same with Items 6 and 7 so that t' end result will be a better fit when one is brought t' bear against t' other, inside t' weight container. Keepin' in mind t' fact that they too will have t' turn freely along t' length o' t' all-thread (Item 4) and inside t' weight container tube (Item 2) o' t' nose weight assembly.

Assemble t' weight container o' t' nose weight assembly as follows. Begad! Takin' t' Nylon all-thread in hand, thread it all t' way through t' nuts on Item 5 until t' length o' all-thread protrudin' from t' nut on t' opposite side is at least ½ o' its outside diameter. Then put t' assembly inside t' weight container tube, me hearties, deep enough t' provide a shallow well for an epoxy fillet t' be applied soon after. Begad! Next, at t' opposite end o' t' weight container, thread either o' Items 6 or 7 onto t' all-thread into that end o' t' weight container. –This operation is very important, me hearties, as it aligns t' all-thread within t' longitudinal axis o' t' weight container tube at each end. –

With CA, tack Item 5 in place and t' all-thread as well. But do nay tack anythin' else at this time. Allow t' CA t' cure, arrr, then remove whichever Item is bein' used t' hold t' opposite end o' t' all-thread at t' other end o' t' weight container tube. Ahoy! Stand t' tube on end and fill t' well in t' forward end with epoxy. Set it aside t' cure.

Next, shiver me timbers, we move on t' t' completion o' t' tool, t' Spanner-Driver assembly.

Item s1 o' t' spanner-driver assembly, aside from t' necessity o' a free fit that rotates and slides within t' weight container tube, me hearties, should also be o' a length that is at least one inch greater than t' length o' t' weight container tube used in t' nose weight assembly.

Assemble Items s4 and s5 o' t' spanner-driver assembly, then glue them in place with epoxy or CA, or both. Arrr! After that, me hearties, you may permanently install their assembly at t' other end o' t' spanner-driver tube, with epoxy or CA, or both.

Now, matey, since Items s2 and s3 o' t' spanner-driver have already been assembled, their installation will finalize t' assembly o' t' Spanner-Driver. Install each assembly accordin' t' t' drawin' provided, and set t' completed tool aside.

In t' next phase o' this particular plan, t' nose weight assembly will be nearly complete as it is introduced t' t' inner sanctum o' t' rocket’s nose. Begad! Moreover, thar be a certainty that is often found in t' necessity for any implementation o' modifications t' commercially manufactured noses for amateur rockets when t' end user’s consideration toward over-building, for t' sake o' safety and success, ya bilge rat, precludes all else.

Click To Enlarge


(Click t' Enlarge)

First, shiver me timbers, we have t' modify t' base o' t' nose so that it will accept a rather large piece o' plywood. This particular piece o' plywood, referred to, as Item 3 in t' nose weight assembly drawing, will serve in three purposes. Begad! (1.) It provides a far superior hard-mount for t' shock cord. (2.) It centers t' aft end o' t' weight container tube. Well, blow me down! (3.) It also strengthens t' lower end o' t' shoulder o' t' nose. Ahoy! Which also raises t' question o' how t' get that big thin' inside there, once it’s been built. Begad!

Click To Enlarge


(Click t' Enlarge)

Please refer t' t' drawin' o' t' nose weight assembly while holdin' t' rocket nose o' your choice in hand, me hearties, and then take careful note o' what part o' t' nose that has been set aside in one illustration named as “Cut-away, shiver me timbers, Aft end, Nose”.

First, me bucko, measure t' outer diameter o' t' shoulder. Begad! Then subtract 1/16 inch. Blimey! T' result o' that calculation, me bucko, rough as it may seem, matey, will be t' outer diameter o' Item 3. Aye aye! Start cuttin' t' shoulder o' t' nose cone right about where t' radius meets t' taper, and go all t' way around. Remove burrs and sharp edges with sandpaper (heavy grit). At t' same time, rough t' inside o' t' shoulder too. Set t' nose aside.

Now build Item 3. Before installin' t' steel U-bolt, test t' fit o' Item 3 inside t' nose. Retrieve t' nose. Then, me bucko, squeeze t' shoulder o' t' nose and slip Item 3 inside. Like puttin' a slice o' bread into a toaster. Avast! Once it’s inside, put a strong finger through t' hole in t' center o' Item 3 and relax your grip on t' shoulder o' t' nose. Aye aye! Flip t' dang thin' so that it is perpendicular with t' longitudinal axis o' t' nose, and then brin' it t' bear against what’s left o' t' aft end o' t' nose’s shoulder.

A slightly sloppy fit is OK! But a tight one is not. Aye aye! In t' event o' a fit that seems too tight, check t' outer diameter o' t' shoulder again. If its diameter is larger than was previously measured, you need t' remove a little bit more material from t' outer diameter o' Item 3. Take it out t' same way you put it in, do what you’ve got’s t' do, and try it again. Ya scallywag! Once t' fit is deemed t' be 3D and cooperatively aesthetic in your personal standards, take Item 3 out and install its U-bolt assembly.

Re-install Item 3. Ahoy! Then insert t' weight container assembly. Push t' weight container assembly all t' way into t' nose until it can go no further. Hold it in place with your thumb while pullin' on t' U-bolt with t' index finger and thumb o' your other hand. Begad! Now, yell for help. When t' Cavalry arrives, instruct t' first member approachin' you from that group t' apply a bit o' CA around t' base o' t' weight container tube where it mates with Item 3. And be sure t' tell them that t' digits o' your hands are nay t' be included with t' fastenin' o' these parts o' t' assembly. Avast! [By t' way: children will listen t' instructions and are fully capable o' followin' them. Girlfriends, wives, and/or a significant other, however, are quite tempted in bein' given t' opportunity t' make a slight mistake.]

Once t' CA has cured, shiver me timbers, mix a small batch o' epoxy and make fillets around t' end o' t' weight container as well as inside t' radius o' t' shoulder o' t' nose, on Item 3. Begad! Wait for t' epoxy t' cure. Through one o' t' ¾” holes in Item #3, shoot just a little bit o' a commercially manufactured “canned” expandin' foam into t' nose cavity. Avast! Give it plenty o' time t' expand and cure. It’s kind o' like shootin' paint, because too much at once is NO GOOD. Begad! If you shoot too much, it’ll take forever t' cure because urethane foam needs exposure t' air in order t' cure. And you’ll probably be scrapin' turd-like extrusions o' foam for days after. So go light, and wait for t' foam t' cure betwixt shots. Aye aye! Clean t' “shooter tube” and t' can’s nozzle betwixt shots, with Acetone. Aye aye! Please be advised that just one (1) can o' this stuff (the expandin' foam) will easily fill several nose cones like t' Minnie-Magg’s.

Believe it or don’t, your very own “Adjustable Nose Weight Assembly” is now complete. TAH DAH! So, Congratulations and Salutations are t' order o' t' day.

Here’s how it works, in t' field and on-site.

-A rocket’s center o' pressure does nay change, me hearties, but its center o' gravity does. Further, t' relationship betwixt t' two is a very important factor in t' properties o' stable flight. And thar be t' basic “rule o' thumb” that t' rocket’s center o' gravity should be at least one airframe diameter (or caliber) ahead o' t' location o' t' center o' pressure when it is made ready for flight. –

Prepare t' rocket for flight, arrr, then tie a piece o' twine around t' airframe and suspend it above your work bench; movin' t' twine fore or aft along t' airframe until t' rocket is balanced. If that balance point is nay at least one caliber ahead o' t' center o' pressure, you’ll need t' add weight t' t' nose.

Stand t' rocket’s nose on t' pointy end, and remove Items 6 & 7 from t' weight container tube. Pour in an ounce or two o' lead shot. Blimey! Blimey! Place Item 6 on t' all-thread (nut first) and carefully thread it into t' mouth o' t' weight container tube by hand.

With t' Spanner-Driver chucked in a portable drill motor, matey, slowly turn Item 6 along t' length o' t' all-thread until it just touches t' lead shot in t' bottom o' t' weight container tube. Begad! Now introduce Item 7 t' t' all-thread but with t' nut facin' “UP”. Well, blow me down! Slowly thread it into t' weight container tube until it just barely touches Item 6. Remove t' Spanner-Driver and reattach t' nose t' t' Rocket.

Then perform t' balancin' act again.

Once t' rocket’s balance point (center o' gravity) is sufficiently ahead o' its center o' pressure, you’re good t' go.

Comments from t' Author:

Each time a different motor is used, take note o' t' amount o' lead shot required in achievin' t' aforementioned relationship betwixt t' rocket’s center o' gravity and its center o' pressure; either by volume or scaled measurement. Usin' lead shot instead o' steel shot requires less space t' be occupied by t' amount o' weight needed. And for consistency, ya bilge rat, usin' just one size o' shot when it is bein' measured by volume alone is recommended.

In t' event that you are attemptin' higher flights with t' implementation o' Optimal Mass, you already know how much t' rocket weighs when it is prepared for flight and exactly how much more weight needs t' be added. Begad! Blimey! That amount o' weight will however, me hearties, vary. Because flight conditions at t' launch site, matey, namely Weather and Geographical Location are variable factors too in pre-flight calculations or simulation.

Contributed by Steven Pasquier

- Post a Comment -

What You Can Do