Upscale Quinstar build(s)

It's a little finicky to balance, but yes. All those laser cut straight sides.

Charles_McG said:

It's a little finicky to balance, but yes. All those laser cut straight sides.

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Cheater. :tongue:

When gluing on the 5 triangular pieces emanating out from the central pentagon, I had to decide how to position them. If I pushed them against the pentagon then it would eliminate gaps, but then they weren't really properly centered over the frame pieces below. So I decided to position them ideally over the frame and not worry about the gaps. Here's the result:

Clearly the best strategy would have been to cut these pieces to fit after installing the pentagon. Anyway, I whipped up a batch of *slightly* thinned CWF, just enough to be spreadable (I need a new tub I think, and found today the HD no longer carries it ) and filled it in.

The astute reader will note that four of the shelves are in place now. I'm waiting until I have my launch lug in hand before installing the fifth. After sanding down the excess CWF, I applied a topcoat of Titebond NRND to each seam. The end result is not, shall we say, "seamless", but it should look good enough when painted.


I must say, things to not look quite as clean when zoomed all the way in like this.

On a separate note, my 29mm motor tubes and retainers came in the mail today, and my centering rings and launch lug should be here tomorrow or Friday. I have not yet figured out exactly how long to make the motor tube yet.

Geez now that I think about it, I hope I remembered to include the launch lug in the BMS order....

Nabbed a pack of F15-0s at HL with a 40% coupon today... so I'll use an actual engine to measure and construct the motor mount. Although the USPS tracking system seems pretty befuddled about my BMS order, so I don't actually have any idea when I'll be getting the rest of my stuff....

Finally got my parts order from BMS. Working on the motor mount, and it's time to glue in the lug so that I can also glue in the last "shelf" piece. Quick fit check and...


Whoops, left a bit too much air there. That's actually going to be pretty annoying to fill, so I think I'll just make another shelf piece. Now that I have a lug in-hand, I can slot the piece much more precisely. For now I glued a lug into position (I got two, so I glued one and will use the other for measuring the shelf).

In the meantime, I decided that the shelf pieces themselves needed a bit of additional support, since they'd be subject to very high drag forces, and in my build they didn't have the tabs slotted into the main frame pieces. So I glued some 1/8" basswood strip pieces underneath in the seams with the frame, which I figure should give them a reasonable amount of additional strength.

The shelf reinforcement seems like a good idea.

More progress.

I installed the launch lug....

That oughta hold. Then I installed my newly-fabricated shelf piece....

Still a bit of daylight, but much less than before. One gloppy Titebond NRND fillet later and it is sealed up. All shelves are now in. Still have a bit of filled work to do (just cosmetic) but almost there.

Next up: motor mount. Getting everything measured properly caused me major headaches, due to the many variables I'm solving for simultaneously. Having an actual pack of F15's on-hand to insert for validation purposes was necessary.

I first had to calculate the length of the motor mount tube, which is the length of the motor plus the 1/2" engine block, offset by how the retainer mounts in, and double-checked by making sure it would stick out of the frame sufficiently for access. Several calculations later, I got it cut and installed the engine block. Next I mounted the centering rings. In the front, I offset them just a bit from the top, to make room for not-really-needed fillets, and on the bottom I placed them so that they would be exactly touching the retainer:


This way the retainer will glue not only to the tube, but also to the rings, which maybe will be a bit more secure (probably doesn't matter). Here's the finished mount.


I then installed that into my piece of BT60:


And here's the crazy thing. When installed into the frame, it looks like this:


With exactly no wasted space, the aft centering ring comes almost exactly to the bottom of the frame. The retainer will completely cover the tubes. Although I had verified all this before assembly, it is still an amazing coincidence that it worked out this way. I was prepared for either (a) the motor mount to stick out from the bottom, or (b) needing to space the motor down a bit from the top so the retainer would stay outside the frame. But no, it all fit perfectly by accident.

Oh, and while noodling around with the upcoming version of OR, I did this:


Fun.

So, is the Cg ahead of the Cp?

And the wing covers are missing

Charles_McG said:

So, is the Cg ahead of the Cp?

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I'll just say yes, and dare you to prove me wrong.

And the wing covers are missing

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Still trying to figure out a way to add them in.:rant: I can get the shelves in though.

FWIW based on having a normal-scale Quinstar that's had a couple of rough landings ... the weakest points are the lower outer edges (they tend to snap off), the vertical struts toward the outside (which will break when those lower edges snap) and the "star points" - where the pieces join (all circled in red below)

If I were doing it all over again (and particularly if I were doing an upscale), I might add a thin layer of fiberglass or an extra layer of paper there.

Last three pieces of wood held in place with rubber bands while drying:


All that remains now is some filling and sanding, and attaching the retainer. Almost there!

Not all (any?) parts of this thing are exactly picture perfect. Case in point: the joints between the two, uh, triangular pieces on each, uh, wing. I have no idea what to call the parts of this rocket.



I decided to add one final bit of reinforcement, underneath the ends of the large triangular pieces:


In addition to giving support to balsa, I'm thinking it might also help stabilize the relationship between the ends of the frame pieces, which could try to relocate on a hard landing. Maybe, I dunno.

In other news, I glued on the retainer...

...and put a layer of epoxy around the inside of the ejection gas hole (some of it even stayed there!)...


....and about a zillion fillets later.....

...construction is finished!!!! Now I wait for an opportunity to paint, and ponder my decal strategy. But she could fly right now if I were willing to send her up naked. Can't actually believe I got this far. I think it came out well, although it could be nicknamed the "Glue Booger Express" because man oh man there are bits of TB all over the place....

Looking good.

I took mine out to the range today - but it was too windy.

Charles_McG said:

Looking good.

I took mine out to the range today - but it was too windy.

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Aw man, I'm really looking forward to a flight report from you. Could be a few months before I get to see mine fly.

I'm looking forward to a flight report from me, also. Weather has not been my friend. I might have to break down and build a 1/4" launch platform for use at the orchard, rather than waiting for one of the club launches at Bong.

I saw launch it nekkid! If all goes well, then paint it. :wink:

TangoJuliet said:

I saw launch it nekkid! If all goes well, then paint it. :wink:

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Although I'm not a fan of flying naked, if I get a suitable launch opportunity for this one before it is painted then it's going up.

I'm sure your fellow rocketeers would prefer that you launch with clothes -on-.

Charles_McG said:

I'm sure your fellow rocketeers would prefer that you launch with clothes -on-.

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You don't know what you're missing.

Ignorance is bliss!

My first and best flight today.


[video=youtube;mBVlR525i94]https://www.youtube.com/watch?v=mBVlR525i94[/video]

Cracked the PLA printed motor retainer on landing. Otherwise a fine flight. Stayed upright for the whole descent - just reversed spin direction.

Charles_McG said:

My first and best flight today.
View attachment 314496

Cracked the PLA printed motor retainer on landing. Otherwise a fine flight. Stayed upright for the whole descent - just reversed spin direction.

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That's really crazy. 200' on a G? I.wonder how how it'd do on a Vmax or Warp9.

Nytrunner said:

That's really crazy. 200' on a G? I.wonder how how it'd do on a Vmax or Warp9.

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I would think short burn, high thrust motors are poorly suited for high-drag designs like this, because they don't want to go fast and won't coast, which is precisely the opposite of the goal of those motors.

The G79 has 1.6s thrust duration; I wouldn't be surprised if the Quinstar flies just as high (higher???) on an F15 with 3.5s of lower thrust.

Disclaimer: I am not expert in these matters. Got the initial idea for using BP F motors in saucers from watching KenECoyote fly his Rocketarium Turbo Vortico on an F15, really nice flight.

My 3mm plywood build around a fiberglass motor mount is pretty heavy. I was happy with this flight. You see the wiggle off the rod (1/4"), which I think is just from the lugs being off center by 19-20mm on a spinning model. Then it straightens out and flies nice. There was almost no wind.

I've not found anyone with a quantitative rule of thumb for thrust:weight for saucers. The only consensus is 'more than regular rockets'. I'll probably explore downward a little - but not a lot.

I have observed, from flying my variously sized Blenders, that height doesn't seem to vary a great deal with impulse. The 13mm Blender doesn't fly too much higher on a B than on an A. Likewise with the 29mm Blender on Fs and Gs. The extra impulse seems to wind up in angular momentum, rather than altitude.

Charles_McG said:

My 3mm plywood build around a fiberglass motor mount is pretty heavy. I was happy with this flight. You see the wiggle off the rod (1/4"), which I think is just from the lugs being off center by 19-20mm on a spinning model. Then it straightens out and flies nice. There was almost no wind.

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Yes, now that you mention it, I see the wiggle. The black smoke trail makes it easy to see.

I've not found anyone with a quantitative rule of thumb for thrust:weight for saucers. The only consensus is 'more than regular rockets'. I'll probably explore downward a little - but not a lot.

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I seem to have forgotten to weigh my finished (well, unpainted but otherwise finished) model. I predicted about 5 oz, we'll see.

I have observed, from flying my variously sized Blenders, that height doesn't seem to vary a great deal with impulse. The 13mm Blender doesn't fly too much higher on a B than on an A. Likewise with the 29mm Blender on Fs and Gs. The extra impulse seems to wind up in angular momentum, rather than altitude.

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That makes some sense, to a certain extent. I do think my regular Quinstar went a good bit higher on a D12 than a C6, but I couldn't quantify it. I still would think that length of burn would be of primary importance since again there's very little coast.

But in any case your flight looked great, I'd be very happy if mine goes as well.

Neil, Eric C got a great picture of my Quinstar over in this thread.

https://www.rocketryforum.com/showthread.php?t=139377

Charles_McG said:

Neil, Eric C got a great picture of my Quinstar over in this thread.

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Very nice indeed!

neil_w said:

You don't know what you're missing.

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Nightmares?

I saw the Quinstar at Hobby Lobby yesterday and after all this fuss over here, I wanna build one too!
Was thinking of steampunking it since no spray painting needed; would there be any interest in a build thread?

If you steampunk a Quinstar I'd be interested to see what you do with it for sure.

Either way you should get one, it's fun.