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Author Topic: OSPREY 20" SPORTS GLIDER Vintage Model Company laser cut kit  (Read 5364 times)
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LASTWOODSMAN
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« Reply #125 on: September 09, 2019, 04:07:03 AM »

Hi John!    Smiley    Maybe I should put a control stick in there too, and the Pilot's forearms too, and his legs ... LOL.   I am rather really looking forward to test glides more and more ...   Cool

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Richard
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« Reply #126 on: September 09, 2019, 04:10:32 AM »

Well just think of the poor guy seeing the ground coming up while legless and armless Cheesy

John
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« Reply #127 on: September 09, 2019, 01:22:27 PM »

OSPREY  20"   SPORTS GLIDER   Vintage Model Company laser cut kit

FUSELAGE TAIL END JOINING

     This was pretty tricky.   It is so fragile and flimsy, I almost broke the fuse sides   Shocked  a couple of times.
     M and B joined the rear portion of the noseblock to the fuse halves, with masking tape strips and a small black,  light rubber band.  The fuse rear ends were double white glued, held together with two masking tape strips, a couple of small balsa plank spacers, and clamped up with a not-too-strong, blue clamp.

Pic #1     3170     The tail end is glued up.
Pic #2     3171     M and B celebrate like on New Year's Eve.

     Time to clear my head,  with a therapeutic walk in the woods,  with my best pal, while the glue dries.     Grin

LASTWOODSMAN
Richard
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« Reply #128 on: September 09, 2019, 01:34:40 PM »

Quote from: LASTWOODSMAN
...so fragile and flimsy, I almost broke the fuse sides
Odd.  Seemed quite robust on the one I built, never felt like I was in any danger of breaking anything.  Vagaries of wood selection from kit to kit I suppose.

The only (minor) niggle I had was having to bind the sides in at frame 8 while the glue set. Oh, and the elastic band that was around the plan makes a pretty good clamp for most of the rest of the cross pieces.  Smiley
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« Reply #129 on: September 09, 2019, 03:18:30 PM »

     Hi Lurker.   I think that Former #8 may now be just three crossmembers.   The instruction booklet does say "The major side pieces of the fuselage (K1) should be handled very carefully, as before the various stiffeners and other structural parts are added, they are quite delicate."     The close call was when I was trying to locate and tape into position, which was not called for on the plans,   the partial nose block to the front fuse halves, and masking-tape them in place, and add a small not-to-strong light rubber band.  Once the band snapped off with a sound just like a balsa wood break.   Roll Eyes   Luckily I got away with it.   Smiley
         The structure is well designed and strong with the rear end taped and glued up, and the Formers #& and #9 glued up, and all the cross members and stiffeners all glued up,  and will be even moreso as they are all added.
        Being a laser cut kit, I thought I would try to very lightly to sand off all of the very light laser cut burns.   In so doing,  I got a cumulative effect of that very thin balsa removal, in that the tab, of the tab and notch, did not quite fit up flush with the notch face, in a few places,  but really nothing too worrisome.   The wood does appear to be nice and light in weight, but I cannot say for sure.

We are late for our walk.    Grin

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Richard
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« Reply #130 on: September 12, 2019, 07:35:24 AM »

I guess that is all well and truly glued together now Richard, and I imagine quite strong now.

John
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« Reply #131 on: September 12, 2019, 01:26:39 PM »

OSPREY 20"   SPORTS GLIDER   Vintage Model Company laser cut kit

MAKING THE LONG LOCATING GAP SLOT GROOVE AT THE BOTTOM OF THE FUSE,  TO FIT AND LOCATE THE RAISED SKID CENTER EDGE

     Here is the first real difficulty that I ran into.  It took pathetic me,  a  long time to figure it out, and also took a significant amount of exhausting exercise of the grey matter of my brain   Huh   -   I think I just got it all figured out, though.   Smiley

     The skid is laser cut to match the bottom curve of the fuse to glue up exactly.   The skid is not symmetrical about the Y-axis.  Forwards and backwards movement of the skid,  is also prevented, by adding a little piece of  1.6 mm sq (1/16" sq) strip balsa, for the tips of the skid to locate and butt up against these balsa strips, at the front and rear of the skid.   That is the  fore/aft location (X-axis).   Now the skid needs to be supported for side to side movement (y-axis) also, as in a crash.

     The skid is made of three pieces of flat balsa, all glued together and sandwiching the middle piece, which has been cut in half, and glued in place, separated a little bit at the cut, just enough, to glue in the Tow Hook wire.   These two center pieces, S2 and S3,  are lightened with circular cutouts of  balsa,  and have "F" laser cut marks at the front of these parts, and  have a raised upper edge lip, that extends upwards,  1.6mm (1/16"),  past  the "matching" upper edge curve, of the two outer sandwiching skid pieces S1.    The front hollowed out piece S2, also has that laser cut "F" on it,   so there is no mistake.

     The raised edge lip, of the skid's middle balsa lamination,  fits into  laser cut slots at the bottom of the fuse Formers and  fuse bottom Crossmember Midbraces.   These notches are three times too large and wide, for the raised edge of the skid,  so small pieces of  1/16" sq balsa strip (1.6 mm sq), used for skid side locators,  are cut and glued to the inside sides of these notches, in order to snugly fit the raised "edge lip" of the middle  skid piece.

       I have marked 5 spots with arrows, pointing to where the wide slots at the bottom, need to be narrowed, by adding two tiny pieces of  1/16" sq (1.6 mm sq) balsa strip, to the inside of these extra wide Formers and Crossmembers (midbraces)  slots, that support the skid's sideways movement  (Y-axis).   That is 10 agonizing little pieces to try to glue on,  that could be avoided (I think),  if the slots were laser cut 1/3 smaller in the first place -  ie  1.6 mm sq (1/16" sq) wide, centered square slots, not rectangular slots.    Just an engineering update to consider for the next run of kits.   

Pic #1     3195     These parts at the bottom of the fuse, at these five numbered spots,  have a rectangular notch,  which needs two small  1.6mm sq (1/16" sq) balsa strips (as per plan), to fill in the sides of the notch, to achieve the correct gap.

Pic #2     3197     This is sort of what the skid looks like.

Pic #3     3200      The parts at all five spots, now have two little locator guide strips, white-glued into the oversized rectangular notches.

Pic #4     3202     All of the little strips have dried overnight.  Here is a better view,  after taping up the fuse nose, to  test fit all of the parts.

Pic #5     3204     Time for the test fit of the clamped up skid pieces.

Pic #6     3205     SUCCESS   Grin   ....   This is why I like laser cut kits  -  Perfect Fit !!   Shocked  Now to keep the fuse straight and glue it all together.   Undecided

LASTWOODSMAN
Richard
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« Reply #132 on: September 12, 2019, 07:10:03 PM »

I wonder if balsa strips running from fuselage station 1 to station 5 was the intent. A long narrow slot would then serve as the "locator" for the skid. The slot perimeter would serve as a tissue anchor around the base of the skid.

Progress looks good!
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« Reply #133 on: September 12, 2019, 08:45:03 PM »

     Hi Indoorflyer.   I think you are right   Shocked  - they should be one long stringer on each side.   I did it all wrong.   Huh   Thanks for pointing that out.    All is not lost, though ...   Tongue  I think I will just glue it all together as it is, nice and even,  then,  with hot water and a small paintbrush,  I will dissolve those white glue joints in no time at all, and remove those 10 little strips,  and then glue in the one piece  1/16" sq stringer, like you said (I think that was the intent now too), on each side of the slot,  for the tissue to anchor on.    Cheesy
     Time to clear the building board and start on a jig or template or something to hold the fuse straight ...

Pic #1   Agony
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« Reply #134 on: September 13, 2019, 05:31:45 PM »

OSPREY 20"  SPORTS GLIDER   Vintage Model Company laser cut kit

MAKING THE LONG LOCATING GAP SLOT GROOVE AT THE BOTTOM OF THE FUSE,  TO FIT AND LOCATE THE RAISED SKID CENTER EDGE

More progress

Pic #1     3212     All the 10 little 1.6 mm sq (1/16" sq) balsa strips were dissolved off with hot water, and new,  continuous support strips were cut out to fit.  One of the two 1/16" sq side support strips for the skid, is all glued up, and the second strip is waiting on the big balsa block.

Pic #2     3215     Before gluing down the second strip (sitting beside the glued on first strip),  I took a small piece of plastic wrap, and wrapped the circles-hollowed-out center skid piece, and covered it with the plastic wrap.  I will use this as the spacer between these two longeron strip supports, while they dry, and then the center lam should just pull out when all the glue dries.

Pic #3     3216     Here it is all glued up, with the plastic wrapped middle balsa lam sitting snug in its "trough", waiting for the glue to dry before removing it.

LASTWOODSMAN
Richard
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« Reply #135 on: September 13, 2019, 09:15:15 PM »

OSPREY  20"   SPORTS GLIDER   Vintage Model Company laser cut kit

And more progress ...

Pic #1     3217     The wrapped center skid piece lifted right out, and the slot is dry.

pic #2     3218      Looks like it fits in the groove pretty well.

Pic #3     3219      Out side pic of the fit of the center skid piece.  Fits perfect - laser cut.  
  
Pic #4     3220     Yikes!  Shocked   Wrong crossmember by my thumb!!    Undecided  Too large - wrong one ...    Never fear - I white glued everything.   Grin Grin

Pic #5     3227     Everything laid out.

Pic #6     3221     Parts left to do.  First look at a decent mock-up pic.  

     It is coming together quickly now.   Cheesy

LASTWOODSMAN
Richard
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« Reply #136 on: September 14, 2019, 06:39:05 AM »

You're on the home run now Richard. A bit of covering and a canopy.

John
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« Reply #137 on: September 14, 2019, 11:44:32 AM »

OSPREY 20"   SPORTS GLIDER   Vintage Model Company laser cut kit

Hi John.    Lots more to do yet ....

-  use pins or glue to attach the pilot
-   istall pilot seat
-   install the rest of the crossmembers
-   a couple of locating strips on the tailplane for fore/aft location
-   glue the main skid together,  consider a thin metal strip on the bottom for hitting the ground,  glue mainskid and tail skid last
-    fit the nose block and sand to shape and wood stain,  and make a little extra space for some more nose weight, and figure out the balance
-   bend up the tow hook wire, and figure out the attachment
-   color scheme -  all orange tissue on the fuse now?
-   how to replace the tissue mistake on top of the wing middle section
-   canopy ?   - I don't think I have canopy glue  -  maybe just very thin pins ?
-    glue the wings on, or just cut all the dowel holes' tissue, and fly with rubber bands holding the wing on ....
-     make a rubber catapult to launch the glider
-   and last but not least,  some arms and legs for the pilot ??

     Mandrake and Bloodroot clear the building board, and prepare for final assemblies and tissue covering of the fuse.

     Here is some really great slow music, by Tim Janis,   that I listen to while modelling.   His work generally concerns itself with strong and descriptive melodies, often regarding the beauty of nature.

Peaceful Relaxing Instrumental Music, Meditation Calm music, "Spring Birds" by Tim Janis
https://www.youtube.com/watch?v=mlbJOv901rQ&t=2972s

Pic #1     3245

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« Reply #138 on: September 14, 2019, 10:56:33 PM »

OSPREY 20"   SPORTS GLIDER   Vintage Model Company laser cut kit

FUSE CROSSMEMBERS

     More progress ...

Pic #1     3244     Mandrake and Bloodroot, Cyber Super Soldiers from the future,  get up early and finish blocking up the fuselage again.

Pic #2     3249     The fuse sides have to be squeezed tighter, to glue in three crossmembers.   M & B have two light elastics pinning the sides tight  "Heath Robinson" style ... ,  while the glue dries.

Pic #3     3248      M & B have used  5 min  Epoxy, to glue the Pilot to the baseplate.     M and B try to wiggle the pilot and baseplate into position.

Pic #4     3254     It did fit, and sat on the four pads just fine.   Now it is all white glued in,  as M & B examine their work.

Pic #5     3255     The Pilot's head barely fits   Roll Eyes   in under that crossmember,  that was just added.     M & B will carve a little bit off of the bottom of that crossmember, right above the head.

Pic #6     3256     Not done yet.   Huh   The bottom nose crossmember has light shining through   Shocked   -  as it turns out, the crossmember diagonally across from this one,  is also a false white glue joint.   We will dissolve the joints with hot water and re-glue them, and brace them up properly this time.

LASTWOODSMAN
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« Reply #139 on: September 22, 2019, 11:32:29 AM »

OSPREY  20"   SPORTS GLIDER   Vintage Model Company laser cut kit

     Moving right along now  ...  lost a few days with broken reading glasses ...   Sad

Pic #1     3291    Here it is with the final crossmembers added and drying.   The two side fuse pieces, at the nose are blocked up for the curve of the nose.   I brushed the outsides of the fuse, at these bends, with water, and when it dried, it dried tight enough to squeeze the nose plug in place, without further adieu.

Pic #2     3294   I re-glued a bottom cross member.   I had gotten a little lazy in the double white gluing department.   Embarrassed

     With the fuse frame done, I knew I had to see if the model balances, before covering the fuse with tissue.     The ballast hole in the Nose plug/Nose block, is  5 mm diam and 13 mm long.   I looked for some straws, that would fit that hole, and stick out further toward the rear, so I could add some more ballast clay weight if needed.   I lucked out   Cheesy   at Dollarama for  $1.25 -  these striped paper straws are solid-walled and fit the hole exactly !    So,  I cut 3 lengths of straw, each 24 mm long, and filled them up with    #1  clay only,    #2  clay and lead shot,    #3  lead shot only,  and sealed off one end of the straw, with small thin strips of Scotch tape.

Pic #3     3321     You can see how far one of the straws sticks in past the noseblock.    #1  clay only  weighs 0.72 grams,   #2   clay and lead shot weigh  2.08 grams,  and  #3  has  13 pellets of lead shot only and weighs 2.37  grams.

Pic #4     3324     The three ballast tubes are now filled.  You can see how it fits into the nose of the fuse -  a nice tight slip fit !

Pic #5     3326     I cut out two wooden dowels for the wings and sanded the tips.   Here she tries on her new wings and tail section.    The elastics are just the right size and strength.   Grin

Pic #6     3327     And a side view.

     Now it is time to check the balance, using the three little, interchangeable paper straw ballast tubes ... 

LASTWOODSMAN
Richard
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« Reply #140 on: September 23, 2019, 06:05:47 AM »

Here we go Richard, as promised, a picture of my bodge for extending the ballast chamber using the scrap from the cockpit canopy acetate.

It's not great because it pushes the ballast weight back towards the tail, but given the size of the noseblock you're rather stuck.  I think if I were to build another Osprey (and I may, they're rather fun) I'd sheet the first 1/4" or so of underside of the first bay in the fuselage and stick as much of the ballast to the inside of that as I reasonably could.  Another possiblity might be to extend the length of the nosebock, but that's likely to ruin the lines of the model.  You'd probably end up with something like a "double ugly" McDonnell-Douglas Phantom. Smiley

I think I'd also go with a suggestion that Andrew D. made; which was to lose the stabilizer dowels and make the empennage a permanent fixture as a way of knocking some weight out of the tail.

Cheers,
Lurk.

ETA.
I am dim.  The obvious solution is to fix the noseblock in place with as much ballast as it will take packed into it. Then glue a ballast chamber tube vertically behind it. You can leave the top open and plug it with cotton wool or similar so you can adjust the ballast to cope with varying windspeeds.  What a clot.  Now why couldn't I have thought of that two years ago?
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« Reply #141 on: September 23, 2019, 12:25:14 PM »

OSPREY  20" SPORTS GLIDER   Vintage Model Company laser cut kit

BALANCING THE OSPREY GLIDER

   Hi Lurker.   Thanks for the info.  Wink    As far as "losing the  the stabilizer dowels and make the empennage a permanent fixture as a way of knocking some weight out of the tail."   Yes, in balancing, I forgot the weight of those two stabilizer dowels and the elastic - 0.39 grams - so I will not put them on.  Shocked
    I think there is already a positive incidence angle on the main wings, and a zero angle (or a little negative incidence) on the stab,  which makes for "decalage"  between the wing and stab (my guess).   So I can then just glue up the stab anyway, right where it is, onto the fuse.
     I will also be "sheeting" infill planking from the instrument panel forwards, two bays to the nose block, on just the top and bottom of the fuse - some contribution to the ballast weight needed.

Wing        4.09
Stab          1.38
Fin/Rudder    0.40
Fuse including instrument panel and pilot     5.47
All Skids      0.58
Nose Block and Nose Plug      0.97
Wire for Main Skid       0.18
Two Dowels for the Wing     1.17
Two Elastics for Wing     0.40
Windshield Plastic     0.53
Two Smaller Dowels and One Elastic for Tailplane   0.39
Straw ballast tube #1 =  2.37 grams
Straw ballast tube #2 =  2.12 grams
Straw ballast tube #3 = 0.74 grams     all three =  5.23 grams
Total equals  15.56 grams (excluding the balast tubes)

It needs at least 5 grams of ballast weight  in the nose to balance.
Wing area is appx.  42.5 sq inches
Total Weight is  appx. 20 grams including the 5 grams of ballast weight.

Wing Loading (grams per square inch) is  20 grams divided by 42.5 sq inches   =     0.47  Grams per Square Inch  -  just under the max guideline of  0.5 grams per square inch, in order to fly ...

Final Fuse Tissue  =  ??
Infill Planking of nose tip  =  ??
Final Clay Weight Weight to Balance  =  ??

Pic # 1      3336 SNIP     Here is how long of a straw tube I need for 5 grams of lead pellets.   A little too long ...

Pic # 2    3337  SNIP      Here is 12 pellets for  2.00 grams ( 1.99 g on the scale ), to fill the noseblock, for starters.  Plus tiny bits of clay to hold it all in place.

Pic # 3     3329  Custom   My balancing setup.   I marked a small black dot on top of each wingtip, on the balance point of the Center of Gravity, as marked on the plan.   The rough cutout of the windshield is stuck for weighing, just in front of the pilot.

Pic # 4     3330 Custom     Here it now all roughly balances.  You can see the wingtips resting on the round head pins taped to the top of the coffee jar.   But  -  I had to add all three ballast-filled small straw tubes - one in the nose ballast hole, and the two others  are just temporarily green masking taped to the top of the fuse -  total of 5.23 grams.   It takes about one third of the gliders weight (  about 15 grams ),  a third of the glider's weight being 5 grams, to balance out this  15 gram  model,  yet I still have a wing loading of  0.47 grams per square inch.  

Pic # 5   3333  Custom     I was considering metal washers for ballast weight.

Pic #6     3334  Custom     Not many parts left ...

     More thinking is now needed for a different way on how to put in 5 grams of ballast into the nose.   Lurker,  I like your idea of a vertical tube, to which you can add or take away weight, for balancing.  There is enough room in the ballast hole of the "nose block",   for stuffing 2.00 grams or 12 pellets  worth of pure lead shot into,  to begin with.   Lurker, what about a square balsa vertical box?  that somehow opens through a "lid" ?? ,   on the top of the sheeting/planking of the nose?   I am still open to suggestions.   Thanks for any help.  First though, before lots more thinking, I must glue on the rear half, of the two piece nose block set up, to the front of the fuse -  glue on the female "nose plug",  that the male end "nose block" plugs into ...

LASTWOODSMAN
Richard
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Re: OSPREY 20" SPORTS GLIDER Vintage Model Company laser cut kit
Re: OSPREY 20" SPORTS GLIDER Vintage Model Company laser cut kit
Re: OSPREY 20" SPORTS GLIDER Vintage Model Company laser cut kit
Re: OSPREY 20" SPORTS GLIDER Vintage Model Company laser cut kit
Re: OSPREY 20" SPORTS GLIDER Vintage Model Company laser cut kit
Re: OSPREY 20" SPORTS GLIDER Vintage Model Company laser cut kit
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« Reply #142 on: September 23, 2019, 03:37:26 PM »

Quote from: LASTWOODSMAN
..what about a square balsa vertical box?  
That's the sort of thing I was, belatedly, thinking of. See the attachment. The right hand sketch shows the arrangement for fitting the lid that's used on the Walthew MK II.  I think you'd get away with a chamber with a fore-aft depth of about 3/16".
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« Reply #143 on: September 23, 2019, 06:03:39 PM »

If "one" were to measure the moment arms of the first bulkhead and the tail assembly,(fore and aft of the CG location on the plan) you might find it easier to lose a gram or 1.5gm at the tail, as opposed to having to add 5gm @ the nose. Divide the nose arm by the tail arm, then multiply that ratio by 5, to determine how much to remove from the tail.
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« Reply #144 on: September 24, 2019, 09:36:31 AM »

     Hi Indoorflyer.   Thanks for your idea  -  "If "one" were to measure the moment arms of the first bulkhead and the tail assembly,(fore and aft of the CG location on the plan) you might find it easier to lose a gram or 1.5gm at the tail, as opposed to having to add 5gm @ the nose. Divide the nose arm by the tail arm, then multiply that ratio by 5, to determine how much to remove from the tail."
     I have yet to do a calculation using the measurement of moment arms.   Would you please explain how  this is done?   Thanks.    Smiley

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« Reply #145 on: September 24, 2019, 10:43:30 AM »

Sure! This is a somewhat theoretical example, but it shows what a "villain" tailweight can be;  an ounce of prevention is worth a pound of cure, to use a time honored saying...
A "moment", or couple, is a force acting at a distance from a pivot point. Much like a teeter totter in a playground, a heavy weight near the pivot can be "counter balanced" by a smaller weight sitting farther away from the pivot.  The moment is the product of force times distance. The static balance is achieved when the moments are equal.

This sketch shows a hypothetical example of how much(a little) weight removed from the tail assembly would have the same effect of adding nose weight. In a practical sense, adding  nose weight is probably the best option. A new tail ass'y could be built, using lighter wood and possibly narrower strips for the outline, to achieve the same results.  My mindset is "add lightness", instead of ballast! So, in this example, a 1.67gm reduction in the tail weight would have the same effect as adding 5gm noseweight. (I'd be interested in knowing if this geometry is close to the actual Osprey measurements)


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« Reply #146 on: September 24, 2019, 11:48:53 AM »

Hi Indoorflyer.   The actual measurements are

Front of nose plug to balance point =  4.0"
Balance point to center(?) of fin/rudder    =  10.75"

Wt =  Tail Weight of balsa to remove, in order to not add nose ballast weight,  is 1.86 grams.

Where am I going to take off  1.86 grams of balsa from the tail now?  widen out the holes in the back of the fuse sides?   Rebuilding the stab and tailplane is not an option though,  Tongue

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« Reply #147 on: September 24, 2019, 12:27:19 PM »

Well, as I stated earlier, the best option now is probably to just add the requisite ballast. I tend to look at plans and kits with an eye on their structure, and if careful material selection has been made.  Moving the peg forward on rubber powered models is also a recommended modification on older designs  At least we don't see too many rear hooks mounted at the tailpost, any longer!
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« Reply #148 on: September 24, 2019, 12:45:57 PM »

Hi Indoorflyer.  Thanks for the advise.   I think I will just build a ballast box.   I thought I was going to have to take a Dremel tool, and try to grind out the balsa, at the back of the assembled fuse.    Undecided   But that would be too dangerous.   Shocked
     I know exactly what you mean by moving the tailpost forward in the first place -  a real cure-all (if you plan to fly your model, of course).
Well, back to balancing.

LASTWOODSMAN
Richard
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« Reply #149 on: September 24, 2019, 03:43:07 PM »

Quote from: LASTWOODSMAN
I thought I was going to have to take a Dremel tool, and try to grind out the balsa...
Ah. No.  Power tools would be a little, umm, shall we say enthusiasticSmiley However... if you nip down to the local chemists or supermarket and pick up a pack of emery boards (those disposable nail files) then you ought to be able to sand the "longerons" - see attachment - to about 2/3 of their current depth without materially reducing structural integrity.  Obviously you're never going to get a 1.6g reduction in weight and some of the weight being lost is close to CG so the effect won't be so marked, but the weight is being lost aft of the CG which will reduce the amount of ballast required up front.

If you hadn't already covered the stab I would also, in line with IndoorFlyer's suggestion of making the empennage structure lighter, have made the LE & TE thinner between the ribs, again perhaps 2/3 or 3/4 of current width because, this being at the far end of the see-saw, you'd get the most beneficial effect.
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