Double Shuttle has double cato

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I was out at hellfire on Saturday. I believe you was behind me in the group photo. I was thinking I had seen that glider before.
I had the purple rocket with the Orange fin, proof of a small world.
 
I was out at hellfire on Saturday. I believe you was behind me in the group photo. I was thinking I had seen that glider before.
I had the purple rocket with the Orange fin, proof of a small world.

Yes, that was me. The Double Shuttle was the only rocket I had left that was intact. I think I see you in the group picture. I don't know how you held that deep knee-bend position for so long.
 
I had a very good flight today with the Double Shuttle using E9's. The lot number was 09 02 09 A. The vent tubes needed just a little bit of masking tape to have the right fit. I have developed a feel for how tight the fit should be. If the fit is too loose, the shuttles will separate at launch. At the last launch the Double Shuttle arced over too early. So I went back and re-did the paperclip elevons. I straightened out the paperclips and put on new duct tape that had gotten too loose. I reduced the elevon "up" to almost zero. I think that the burned out motor case is probably giving a good nose up contribution. This time the model went straight up. I'm not sure there is much difference between E12's and E9's for this model. This is undoubtedly the most reliable glider that I have in my fleet. I have a video from my Canon Powershot SD1000. The zoom is not good, but if you look closely you can see the shuttles separate.

https://www.youtube.com/watch?v=0trbH6sFxJU
 
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Glad you've got this going for you! It's one thing to fly a kit glider often and well enough....but....it's not really 'yours', until you do something like you've done with Double Shuttle. Reminds me of those 'personal epiphany' moments from days of yore, such as the original design Marauder twenty years ago, my first F powered glider thirty years back, and of course, the original version Astron SST back in '90, before I even joined Tripoli.

Maybe you oughta make a slight upscale of this and use the Estes F15s, perhaps such as a 20 -25% margin.

Sorry to hear about the Mega Baron and especially the RC Blackbird dorking on you. Hmm, still have that free flight version sitting in my shed, hasn't flown in fifteen years, probably isn't going to again either. Too bad someone doesn't use that and mod it for RC, or that even worth it?
 
Did you launch that in the after noon or did I miss it? Me and the kids love that rocket it's one of our favorites and it always seems to get a big cheer from the rest of the crowd.


TA
 
Did you launch that in the after noon or did I miss it? Me and the kids love that rocket it's one of our favorites and it always seems to get a big cheer from the rest of the crowd.


TA

Thobin, I think it was late morning or early afternoon. If it was afternoon it might have been around 1 PM. We were all so busy. I didn't realize that you were there until I saw you from a distance setting up on the faraway pads.

Glad you've got this going for you! It's one thing to fly a kit glider often and well enough....but....it's not really 'yours', until you do something like you've done with Double Shuttle. Reminds me of those 'personal epiphany' moments from days of yore, such as the original design Marauder twenty years ago, my first F powered glider thirty years back, and of course, the original version Astron SST back in '90, before I even joined Tripoli.

Maybe you oughta make a slight upscale of this and use the Estes F15s, perhaps such as a 20 -25% margin.

AstronMike, Thanks for the encouragement! I think your scale-up idea sounds intriguing. I have thought about a double (factor of 2) scale-up, but the more I think about it I am concerned that the weight may go up faster than the wing surface area. It may be that I am near a good size right now. A slight upscale sounds interesting. I will keep it in mind. I may not get to this idea this year, because I already have enough ideas for winter projects.
 
AstronMike, Thanks for the encouragement! I think your scale-up idea sounds intriguing. I have thought about a double (factor of 2) scale-up, but the more I think about it I am concerned that the weight may go up faster than the wing surface area. It may be that I am near a good size right now. A slight upscale sounds interesting. I will keep it in mind. I may not get to this idea this year, because I already have enough ideas for winter projects.

Interestingly enough, a larger glider can actually handle more weight than a smaller one, proportionally speaking. The quantity to scale by is the "cube wing loading" or W/S^1.5, where W is weight and S is wing area. For example, doubling the wing area would allow you to increase the weight by about 182%, or nearly triple for the same flying characteristics. Obviously, keeping the weight below that number will result in an even "floatier" glider

Doing this another way, typically we think in scale factors. A glider that is twice as big (in each dimension) will have 4 times the wing area, and can be eight times heavier for the same flying characteristics. Doubling the size at four times the weight would result in a better flying glider.

Cube wing loading doesn't scale perfectly across large size differences (several orders of magnitude). However, typically larger aircraft will be even heavier than scaling by cubic wing loading would suggest.
 
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Brian,

I am puzzled by the W/S^1.5 scaling. I would think that the scaling would be W/S = L^3 / L^2 = L. What am I missing?

On a different note I launched the Double Shuttle successfully twice today. Both flights were E9-4's. One lot number was 09 02 09 A, which I used successfully last time. The other lot number was A 01 04 13. I second flight went horizontal and did not get the vertical altitude it should have. Post-flight inspection showed that both motors fired. I noticed that one of the motors on the first flight had quite a bit of internal charring. I don't know if this was the problem or if the model got started in the wrong direction somehow. For the second flight I ran out of Q2G2 igniters, so I used the Estes igniters with black pyrogen. This worked and in fact the second flight was straighter than the first flight, although I think I would have liked more altitude. I will try E12's next time.

IMG_2637.jpg This is the first flight to the left. Perhaps it is turning. IMG_2639.jpg

This is the second flight. I flinched on taking the picture, but it does look straighter. View attachment 187811
 

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What you are saying is basically the same thing I am, just formulated slightly differently. If W/S scales linearly with L (as you implied), then the factor W/S^1.5 (= L^3/L^3 = 1) would remain constant across all sizes (as I implied). Other factors complicate the problem slightly, but if you are sure to maintain the cubic wing loading constant, qualitative flying qualities should also remain relatively constant.
 
I had bad luck with 2 launches of the Double Shuttle, yesterday. Both launches used the old Estes igniters with black colored pyrogen, since I no longer have the Q2G2 igniters. For the first flight both motors fired correctly and the flight up was straight and good, but the gliders never separated. I didn't see any sign of ejection charges going off, but it seems hard to believe that there could be 2 ejections charge failures, unless they were wimpy charges. The motors were E12-4 with lot number 06 22 12. I thought for sure the model would be totaled. Evidently, the model found some soft dry dirt and buried itself about 5" without any significant damage, so I flew the model again with E12's and the same lot number. On the second flight only one motor ignited, so I figure that my luck with Estes igniters for clusters finally ran out. As I recall the last 2 out of 3 flights with Estes igniters for clusters worked for a reliability factor of 67 percent. One of my fellow club members suggested dipping Estes igniters in pyrogen, so I may look into that. On the second flight the double shuttle only went about 15 feet high before diving into the ground. There was a slight separation of the gliders from the one ejection charge and one broken fin. I don't know what caused the bad Double Shuttle launch day, besides the igniters on the second flight. It could have been bad Black Powder motors or the gliders were fitted too tight together or a combination of both.

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My old Double Shuttle finally met its demise at Hellfire-20 in the summer 2015. As I recall one motor did not work either due to failure to ignite or a CATO. The Double Shuttle preferably used a cluster of two E12-4's. The E12 having a better success rate than the E9. I had contemplated using the 3" LOC tube again for the new Double Shuttle, but Frank Burke pointed out to me that the T300 from Balsa Machining Services (BMS) is lighter. Although, the T300 tube is nominally a 3" diameter, it is a slightly smaller diameter than the 3" LOC tube. So, having a smaller diameter tube I bought the corresponding nose cone from BMS and they were good enough to cut the nose cone in half for me. They did a good job and I was able to use the split nose cone to help determine where to find the lines for cutting the T300 tube in half.

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I am making a pair of bulkheads for each glider, which will also serve as motor mount structures. The bulkheads were cut out of 1/8" balsa using an Xacto knife. Each balsa bulkhead will have a 1/64" plywood cover glued on to each side. The semi-circular portion of the 1/64" ply were cut out using a strong pair of scissors. The center circle was cut with an Xacto knife.

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I am making a pair of bulkheads for each glider, which will also serve as motor mount structures. The bulkheads were cut out of 1/8" balsa using an Xacto knife. Each balsa bulkhead will have a 1/64" plywood cover glued on to each side. The semi-circular portion of the 1/64" ply were cut out using a strong pair of scissors. The center circle was cut with an Xacto knife.

Pretty nice work!
 
I got my custom order from The Sandman at Roachwerks (or Excelsior) today for the Double Shuttle vent tube bulkheads. I laid the parts out for a dry fit, but have not glued anything yet. I ordered enough 3 bulkheads for each shuttle (half shell), but I am still deciding whether to use 2 or 3 for each shuttle. The hole diameters in the bulkheads are on the order of 24 mm to accommodate BT-50 tubes.

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I worked on the motor mounts the past 2 days. I first put engine blocks in 2 short sections of BT-50 tube and secured the engine clips with drywall tape and 5-minute epoxy. The end of the drywall tape tends to unwrap a little bit so I secured it with masking tape until the 5-minute epoxy started to take hold. My BT-50 tube is thin-walled so I used epoxy rather than Carpenter's glue, because I was concerned that the yellow glue might swell the BT-50 tube and then the motors might not fit good.

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Afterwards, I glued the motor mount tubes to the thin bulkheads described in a previous post #44 using 5-minute epoxy. At first I thought of using just one thin bulkhead per motor mount tube, but I decided that the motor alignment might be better using both bulkheads. I cut off about 1/16" of the flat part of the bulkhead with a scroll saw before gluing in order to have a better dry-fit with the 3" diameter half-tubes. Cutting is a lot easier than sanding. The dry fit is shown below.

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I've ordered BT-50 coupler tubes from both erockets and Balsa Machining Services in the 1" and 4" length. These couplers look the same for both companies. The couplers are shown in a photo below. I slid a 1" coupler into each motor mount tube from the forward end to abut the engine block. I did not glue in place because the fit was tight and also painted the tube forward of the coupler with sodium silicate solution (waterglass). The idea is to help protect the BT-50 tube from those nasty E-12 motors. I will avoid E-9 motors completely.

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I then glued in the motor mount tubes to the large 3" diameter tubes with yellow glue. Then I selected 2 balsa vent-port bulkheads that did a dry fit well with the glued motor mounts mounts. I applied 30 minute epoxy to the balsa bulkheads and slid them in place.

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In a similar fashion as in the previous post I glued in the remaining BT-50 tubes and vent port bulkheads. I cut off two pieces from a long 1" diameter wooden dowel as end plugs for the last vent port bulkhead. These were glued in with 30-minute epoxy like the the BT-50 tubes and bulkheads.

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I have 2 wings, one for each shuttle, already prepared (These are 1/8" thick balsa with 20 pound stationery glued to each side using white glue). So, today, I cut three 25mm holes using an Xacto knife in each wing for the vent ports. This had to be measured fairly carefully in order to assure that the vent ports will line up when the wings are glued on to each shuttle half. There were a few epoxy burrs in the vent hole bulkheads that I touched up with a Dremel tool. I have a short piece of BT-50 tube that I can put in the vent holes as a marked gauge to check for the BT-50 tube alignment. The next step will be to glue on the wings.

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I cut out short lengths of BT-50, which will serve as vent tube liners going in the perpendicular direction to the main glider axis. I used the internal diameter of a BT-50 motor mount as a tracing for the vent tube holes that connect the main axis of the vent tube. The forward most vent tube needs only one vent hole aligned with the main axis. The vent tubes on one glider were made long enough to fit in the other glider for the purpose of alignment. Later I glued on the wings and cut these perpendicular vent tubes to be flush with wing surfaces.

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For repair work those Dremel tools really earn their keep.
Okay, I'll be the one in the crowd who goes there - isn't there a famous saying something like "We can rebuild them, we have the technology"? :wink:
 
Okay, I'll be the one in the crowd who goes there - isn't there a famous saying something like "We can rebuild them, we have the technology"? :wink:

Hopefully, we can re-build them to fly again and the E12-4's will cooperate.

I needed to glue on a piece of 1/8" thick balsa on the bottom of each nose cone half to bring the lower surface up to match the wing on the main fuselage. I also glued on some white 20-pound stationery to complete matching the surfaces. I put on an epoxy fillet along the wing/body tube interface. I am currently testing the coupler tubes in the vent tubes as dry fit to decide how to make this work.

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I cut and glued in the BT-50 coupler tubes shown in two lengths (1" and 4") back in post #48. The aft and middle coupler tube were cut from the 4" length and the forward coupler tube was cut from the 1" length. All coupler tubes were used on one side and had holes cut so that ejection gases can run the full length of the model. The middle and aft tube were pushed through all the way until they stopped. The aft tube sticks out .65". The middle tube sticks out 0.5" and the forward tube sticks out 0.25". I did this by trial and error, so that that both halves fit together snugly, but can pull apart with relative ease. All the tubes were put in with a small amount of white glue. I prefer white glue in this situation so that swelling would not be a problem. I put a little bit of thin CA in the thin wall BT-50 tubes on the other side to stiffen them up a little bit. I did have some alignment problems with the forward vent port and found that I needed to round it a little bit with my Dremel tool.

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Hey, a good fabricator can overcome engineering errors. (I know, because I am an engineer. :blush: )

Very good description.
 
I glued in the half nose cones with 30-minute epoxy. Actually, about 2" of the forward 3" diameter tube was not glued to the flat papered balsa wood, so I glued that at the same time. I put a rubber band and masking tape around the forward nose during the gluing, so that the two forward nose pieces would be close together. This will help prevent the air flow getting in between the two gliders and separating them prematurely in flight. I noticed that afterwards the half gliders fit together better and smoother than before. Perhaps, the two gliders fit together too loose. I can always visit this issue later. There might even be a way that I can lengthen the forward vent tube to make a tighter fit.


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Keep up the good work!

Thanks, Daddy. The process is continuing.

I took left-over papered balsa and marked the pattern for 4 side tail-fins. Instead of cutting out the tail fins by hand using an Xacto knife, I decided to use my scroll saw. The papered balsa is fairly tough, so I did not relish the job of cutting out the tail fins by hand. (I wish some manufacturer made this papered balsa in large sheets.) It turned out the cutting the tail fins with the scroll saw worked fine and it was fast and easy. I tacked the tail fins in place first with medium thin CA and then put in place fillets with 30 minute epoxy.

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I found some more scrap papered balsa and cut out 4 elevons with the scroll saw. In the very first Double Shuttle I used Great Planes 3/4" x 1" CA Hinges, but I only have 2 left. However, I found that I have plenty of Hinge tape, so I taped the elevons on. Attaching a paper clip to hold the elevons in place will be the next step.

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