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  #21  
Old 03-05-2021, 07:33 PM
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The 29mm engine mount.

The LOC engine mount tube that I cut to 8" long wouldn't go into the male threaded engine lock ring without a great amount of sanding. Using 120 grit I sanded the tube--rather than the 3D printed ring so as not to weaken the ring. After I achieved a slip-fit I mixed up more 30 minute epoxy and assembled the engine ring, the rear CR (at top,) and the forward CR (at bottom.)

TBC
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  #22  
Old 03-05-2021, 07:36 PM
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That is a pretty good fit between parts A and B. Parts surface looks good too, though I know you said the “Vixen” (if I may....) did some surface sanding on those parts. What is her report on just how much sanding that required and how much elbow grease did it take?

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  #23  
Old 03-05-2021, 07:54 PM
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"The Vixen" claims she sanded the parts (PNC sections, fins, lugs) for approx. 8 hours total. She started with 120 grit and ended with 220 grit. She tried getting them smoother with 320 and 400 but the finer grit papers did nothing but load up. Even with the cutting action of the 120 grit she still had to lay into it and had to rest every half hour to relieve the cramping and to refer to me as "being attracted to my own mom and that my parents were not married." Fortunately I was out of state the whole time she worked on them.

I'm taking her out for a mani/pedi on Sunday--gladly!

TBC
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  #24  
Old 03-05-2021, 08:02 PM
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I need some help, please.

I've looked ahead in the instructions to page 8: balancing. It says to mount an Aerotech G53W-7 into the model. I don't have one of those yet, so can someone tell me length and the weight of the G53W-7 engine so I can make up a dummy for the balancing?

Thanks!

TBC
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Last edited by jeffyjeep : 03-05-2021 at 08:27 PM.
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  #25  
Old 03-05-2021, 09:11 PM
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The recovery tether.

The twisted Kevlar cord that was included int he kit isn't good enough IMO, so I'll instead use a length of my best 400lb. braided Kevlar. After calculating what the distance will be from the front CR to the open end of the BT101 (11.75" in this case,) I cut a 36" piece of the 400lb. braided Kevlar. I then make an overhand loop in the middle and tie a stop knot on both loose ends at 11.5" from the top of the loop above the center knot. This way the Kevlar won't extend out of the front of the BT101--but is still long enough to pull out of the rear of the engine mount if necessary.

After reaming the holes in the top CR with a Swiss file I feed the loose ends of the Kevlar tether through the holes and join them on the other side of the top CR with a square knot. I then cinch the knot and enrobe it with epoxy. I feel this part needs to be over-engineered because it will never be seen again--unless there's a disaster.

The engine mount is now ready to be epoxied into the BT101.

TBC
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  #26  
Old 03-05-2021, 09:24 PM
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Inserting the engine mount.

After tucking the tether into the engine mount tube for safekeeping I apply a ring of 30 minute epoxy to the ID of the BT101 at c. 10" from the rear end of the tube.

Now for some technique: the CR's are a pretty easy fit--not too loose, not too tight. I cut a scrap piece of BT80 to exactly 2.25", which is the insertion point of the rear CR. Since I don't want the epoxy to "pool" from laying the BT101 on it's side as the glue sets, I place the 2.25" BT80 on my bench, place the engine mount assembly on top of the BT80 (registering the rear surface of the CR to the edge of the BT80, of course) and I then lower the BT101 onto the propped engine mount. I'll let this sit here for a while and let the epoxy migrate down around the top CR.

TBC
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  #27  
Old 03-05-2021, 09:40 PM
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With the epoxy of the top CR cured enough to flip the BT101 over without the engine mount assembly moving, I turn it over and apply a generous bead of epoxy to the rear CR which I'll let migrate down around the outer edge of the CR to mate it with the ID of the BT101 for ever and ever.

Time for some Scotch! Good night.

TBC
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  #28  
Old 03-05-2021, 10:03 PM
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Quote:
Originally Posted by jeffyjeep
I need some help, please.

I've looked ahead in the instructions to page 8: balancing. It says to mount an Aerotech G53W-7 into the model. I don't have one of those yet, so can someone tell me length and the weight of the G53W-7 engine so I can make up a dummy for the balancing?

Thanks!

TBC

I balanced my Soyuz the same way, with a simulated spent G77 engine. Weight was 1.75 ounces and case length was 4-5/8". I don't see a listing on the Aerotech chart for the G53W-7, but they show one with Fast Jack propellant that has an unfired weight of 5.15 ounces. I balance all my models with a spent engine case and a CG of 1.5 to 2 calibers and they fly straight.

Last edited by erik442 : 03-05-2021 at 11:28 PM.
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  #29  
Old 03-06-2021, 10:07 AM
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Quote:
Originally Posted by erik442
I balanced my Soyuz the same way, with a simulated spent G77 engine. Weight was 1.75 ounces and case length was 4-5/8". I don't see a listing on the Aerotech chart for the G53W-7, but they show one with Fast Jack propellant that has an unfired weight of 5.15 ounces. I balance all my models with a spent engine case and a CG of 1.5 to 2 calibers and they fly straight.


Excellent! Thanks.
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  #30  
Old 03-06-2021, 09:32 PM
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Prepping the BT101.

Now that the engine mount is epoxied into the BT101 it can take a some intensive handling with less danger for being damaged.

Since this is scale and very special I'll fill the spirals. I've done this with diluted Elmer's Wood Filler and then I let it dry all afternoon. This evening I sanded the spirals with 220 grit and then buffed the entire tube with #00 steel wool to eliminate the "nap" from being sanded.

TBC
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