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Discussion in 'Low Power Rocketry (LPR)' started by luke strawwalker, Mar 4, 2009.
Some pictures I took outside on this sunny day.
She looks great!!
It flew today at my son's school's field on a B6-2, I won't try it on a C in a ball field again after nearly losing the first one I built. But today's flight was perfect. I'd made sure the shuttle had the same CG and the same amount of elevator setting as the last one, and it flew just as great. I love watching these fly!!
The landing was less than perfect as the front launch lug under the nose broke off when it hit the gravel. No other scratches or damage. This will be an easy repair.
I also, unfortunately, lost my Baby Bertha again to a rocket eating tree when I launched it on a C6.
awesome news! the Zooch shuttles are a blast to fly!
After building my last shuttle I had so much fun I didn't want to stop so I decided to build the entire fleet of orbiters, one of each name, using the wraps. I stopped by Home Depot to buy a pack of wooden screw plugs (used as the nose of the orbiters) but I bought the wrong size because I failed to measure first. Oops. The ones I got were 3/8", which was 150% larger than the 1/4" plugs that come with the kit. Obviously the only logical next step is to build a complete model 150% scaled up!!!
I've never built anything scaled up so this was a really interesting challenge for me. It wouldn't be as simple as I used to think.
Since I don't have a printer at my house capable of printing on 11"x17" paper I took a copy of the Challenger wraps to FedEx and asked them to print the sheets at 150% scale. At home I was able to print the scans I'd made years ago of the original templates and used those, along with some scrap balsa, to try to make the nose section of the orbiter first. Maybe that wouldn't turn out well and I'd change my mind.
Here's the finished nose section next to the "stock" version of my Discovery (made with the wraps).
It's definitely bigger!!
If I did decide to finish this and fly it I'd definitely need to add nose weight, so like the stock instructions say, I cut a hole in the back, for adding clay later.
It took a while to finish the orbiter but it went together about as smoothly as the stock size build went. I had to find a larger nylon screw for the back of the orbiter and then cut it shorter. When the orbiter was finished I had to find out how much nose weight to add, but first the CG needed to be located. Balancing the orbiter on the edge of my metal ruler it was much further back than the Discovery was (as expected). The nose section is held on only with a small piece of blue painters tape, allowing me to add clay as needed.
I wasn't able to weigh the clay before adding it since it went in multiple pieces, as I checked the CG a half dozen times while adding weight in between. I could have weighed it before and after, but I didn't, so I have no idea how much I had to add. Eventually the CG matched the location of the Discovery, right at the back of the flag.
For comparison purposes, here's the finished 150% scale Challenger next to the "stock" Discovery. I keep putting "stock" in quotes because in the kit you don't use the wraps, these are 3rd party. But I'm using it to compare since I also used the wraps on my Challenger.
(Note, the thicker black areas on the wing, where the leading edge of the wings meet the cargo bay, were only on Columbia (edit to correct the name). Future orbiters didn't have them. I didn't notice these until I'd already built my Challenger or I would have removed them from the wrap prior to printing. Oops.)
The "stock" Discovery weighs between 13 and 14 grams. The scale switches between those weights as air currents blow on it I think. You can see the small amount of weight I added to the left wing to get it to turn instead of flying straight.
Scaling up 150% in length doesn't equal 150% increase in weight. The larger orbiter weighs in at 46 grams.
I have NO idea if this will fly or not and if pressed I'd probably bet that it won't. When I fly it I'll definitely document the flight and report back here.
Upscaling the orbiter was relatively straightforward. I just had to print the wraps and templates at 150% of their original size. But the SRBs and ET would be different. I'd scanned the wraps from my original kit years ago but the tube sizes were not exactly 150% bigger. The SRB tubes for the upscale were the standard BT-55, so if I'd just printed the wraps 150% bigger they wouldn't wrap around exactly right. So I scaled them to 150% of the height, but had to calculate the ratio of the two circumferences to figure out how wide they needed to print. Once that was done and the image was resized I had FedEx print them on card stock and I glued them on tubes. I had to roll the prints up and stuff them into a body tube overnight to make sure they were curled properly for gluing. The SRB skirts also had to be scaled to fit a BT-55 instead of just to 150%.
Here are the bigger SRBs standing up next to one of my earlier stacks.
Here are the SRBs and the bigger flame fins with primer only. The flame fins templates were easy to scale by 150% and print so I could cut balsa. I had to buy a couple of big balsa sheets (4" x 36") to cut all the fins, wings, spars, etc. out of for this model.
One of the trickiest things about this upscale was the nosecones. In the kit, the ET nosecone comes with an offset weight that is preinstalled by the Dr. Zooch factory. Looking around online I couldn't find any balsa nosecones of the correct shape so I ended up ordering one custom made from Gordon at Excelsior Rocketry. He had the dimensions already and was able to turn one for a VERY reasonable price. He shipped it to me and 2 days later I was covering it with wood sealer. I will HIGHLY recommend Excelsior to anyone. Gordon was extremely easy to deal with.
I had him drill a blind hole in the nose, so I could put in some weight of my own when I decided how much to put in. I ended up needing to enlarge the hole some with a Dremel and make a guess on how much weight to add. I put in enough to bring the CG to the same place as on the stock version. I hope that works.
For the intertank structure I bought some corrugated paper from Michael's. I had a devil of a time getting that stuff. I won't list all the details here but it involved me driving all over town and about a weeks worth of phone calls and trips before finding it on a shelf 10' from where I'd looked to begin with. It's a shame people who work in retail don't have a better knowledge of what is in their stores or the first person that "helped" me that day would have saved me a ton of headache.
Here's the BT-80 ET with the seams filled, cone in place, and intertank corrugation in place.
Right behind it you can see the motor mount ready to be glued in place. I bought an Estes motor mount kit at a local hobby shop for a D or E engine mounted in a BT-55, -60, or -80. Luckily there were 4 centering rings that were the exact size I needed to put on the flame fins so they'd fit inside the BT-55 SRB tubes!! One less thing to worry about.
For the tank bottom I also didn't upscale it exactly 150%, I figured out the ratio of the diameter of the tank to the original and used that scale to print it. I then used the motor mount tube as a guide to mark where to cut out the Cut Out in the middle. Those that have build the kit know what that is. After shaping the bottom to a dome and covering the back with glue to add support, I used the depth to determine where the lowest centering ring would go on the motor mount, which glues to the bottom edge of the tank.
I painted everything the same as I'd done on my Discovery model. I put on 1/4" launch lugs since I was probably launching this on a D engine, and maybe an E someday if it flies okay. I had to cut away a section of the corrugated intertank so the rod could slide freely, but touched up the paint so you probably can't tell without me showing you where the missing part is.
The nosecones for the SRBs were also ordered from Excelsior after I grabbed the wrong ones at JonRocket. The folks at JonRocket were nice enough to cancel my initial order on a Sunday after I bought the wrong cone for the ET. I notified them in time to stop the order. Unfortunately the order I did make for the SRB cones was wrong too but I didn't know it until they arrived. Excelsior turned a couple of custom cones for me and a few days later I'd had them painted and glued on too.
For the parachute, I looked online and found a chart for chute size vs weight. I had to estimate the weight at the time since I was not done and decided I needed an 18" chute. Digging through my spare parts I found an 18" nylon chute and I have no idea where it came from. So I used it.
After finding where the CG of the completed rocket needed to be and adding the correct nose weight to the ET nose, I weighed the entire stack, loaded with a D engine, at 351 grams. Wadding will add a little more I suppose.
Here's a picture of the final 150% upscaled Challenger stack standing next to the "stock" Discovery stack.
I'm planning on flying this on a D12-3 as soon as I get a week of sunny weather so the big field near me is all dried out. I don't want it to land in a puddle of water. As of today we've had a week of rain.
The entire stack could curve over and hit the ground under power, leaving me with a pile of shuttle pieces. Or maybe the stack will fly high and the orbiter will come off, but it won't fly and will plummet to an early death. Anyone want to make a prediction?
Don't worry about the weight of the upscaled orbiter. The bigger you go, the lighter they fly.
Many other variables at play here, like balsa sheet thickness, but mass/weight typically tend to scale with to Volume rather than a linear length scale, so Volume scale ratio would be 1.5^3 = 3.375, your 150% scaled-up Orbiter weight comes in about 3.54 X the original, not too far off.
Your scaled-up model looks totally awesome!
Mushtang...that looks INCREDIBLE!!!! beautiful job!
It looks good now. Not so sure it will after First Flight. Ha!
Fantastic work! Good luck on the test flight
I actually used the above fact to out geek some very knowledgeable space geeks while working at KSC. However you have the wrong orbiter. Columbia is the only one to have the Black TPS tiles on the Leading edge strakes. http://www.nasa.gov/centers/kennedy/shuttleoperations/orbiters/columbia_info.html
Ahh, you're correct. I did type Discovery instead of Columbia by mistake. Thanks for catching that. I had Discovery on the brain from the pictures but had recently built the STS-1 Columbia version with a white tanks and got mixed up.
Good catch! I'll go edit my post just in case someone else reads it later.
Finally launched the 1.5x version today on a D11. The stack flew up fantastic, just like the original version, but the orbiter failed to glide. It fell nearly straight down, nose first, and the rudder broke off on impact. The rudder is easily fixable, that's not a problem.
My guess is there's too much nose weight in the glider? The CG was in the same relative position as the smaller version, and the elevator was positioned in the same angle. For this bigger version there isn't a lot more travel left to bring the elevator up, but there is some.
Anyone have any suggestions? My plan is to try and cut the nose off and build a new one, and put far less clay in it so that the CG is much further back. If it doesn't come off clean I can build a completely new orbiter I guess. But the only thing I can think of is that the CG needs to move back but I have no idea how far.
The nose section came off surprisingly easy! I slid my hobby knife behind it and started cutting, by the time I got it all the way around it just popped off.
The clay in the nose hadn't hardened, so after I opened up the square hole in the back a little bit I could use some tweezers to pull small pieces of clay out at a time. I taped the nose to the orbiter and checked the CG, removed some more, checked again, removed some more, etc. Eventually I got the CG about a half inch back from where it was.
I glued the nose back in place and I'll test fly it as soon as I can.
Hi, new guy here. I built two Estes 1284 kits over 20 years ago and was planning on building the entire fleet, but then I lost interest in model rocketry before even attempting to fly my shuttles. My Estes shuttles are long gone, but I am now getting back into model rocketry and just purchased a Dr. Zooch shuttle. I'll see how the first build goes, but I hope to eventually build the entire fleet. This thread is an excellent reference that should be a big help for my build.
I plan on using the wraps in post #495 to build my first orbiter, Atlantis. As a few people have mentioned, the thicker black areas on the wing, where the leading edge of the wings meet the cargo bay, were only on Columbia and were not present on the other orbiters. Has anyone corrected the wraps to account for this? I'm sure I can hack up the pdf files and try to correct them, but I figured I'd ask here first to see if anyone has already done this (and probably did a better job than I could do).
Also, I plan on using 65# card stock on all the wraps; I think the stock wraps are all 110#, except for the bottom wrap. Does anyone foresee any problems with this, or should I really go out and get some 110# card stock?
I don't know of any of the files being corrected yet. I only noticed the error a few weeks ago.
I think 65# for everything including the bottom would be fine. There's no reason that I'm aware of to go heavier on the bottom.
As you've probably already read several times, build your first one stock, and don't use the wraps. It's a little bit easier, and it's more likely to fly correctly. Building the entire fleet using the wraps will be easier for you after you have the experience of building stock. Plus you'll have the stock build to compare weights and CG to.
Are you planning on getting a new kit for each build, or making one ET and SRB stack and having all the Shuttles built separate on your own?
I'd like to get at least a couple of kits so that I have at least one spare ET and SRB stack. I'm not sure where I'd find the wood plug for the nose or the screw for the back, though, if I built my own orbiters. I do have my eyes on a few other Dr Zooch kits (SLS and Saturn V are at the top of the list) so it would be great if I could save some money on the shuttles to put towards the other kits.
The nose plugs are 1/4" wooden screw hole plugs (also called Button Plugs), they sell them at Lowes or Home Depot. The small nylon screws can be found there too, but be sure to get the smallest possible they sell. You may have to special order a box of them online to get them small enough.
After you build the stock orbiter it might be easier to make the entire fleet at the same time, instead of one at a time.
I will go ahead and beg you now, PLEASE take tons of pictures and post them here of your builds as you go. Let us enjoy your creations as they happen.
I've tried to fly this twice now after the nose weight was reduced, and the glider just tumbles down, doesn't glide at all. Not sure what to try next.
Mushtang, how does the orbiter glide when hand tossed? Did you adjust the elevator when you lessened the nose weight? how does it tumble, nose over tail, in roll, more of a spin or all 3 axes? If you can't get enough speed hand tossing it you might be able to rubber band catapult it for test flights. What was the orientation of the stack at separation, I could see if it still pointing up where it might have a difficult time recovering. I'm not a glider expert by any means but those are the things I'd ask myself.
I haven't tested this orbiter by hand tossing it since the last couple of times I tested the normal sizes orbiters the tests weren't helpful. On those, sometimes it would glide and sometimes it would tumble, but they glided every time from being launched.
When I removed the nose weight I didn't make any adjustments to the elevator since it was in the same relative position that the other orbiters flew successfully. I wanted to change only one thing at a time and see if I could get a better idea of what was wrong. Not sure if the position of the elevator would cause a tumble vs glide.
From what I can tell it was more of an all three axis tumble. I have a video that I haven't taken off the camera to watch on my laptop yet. Was of town all last week on business and was too bummed to look at it the day of the flight.
When the orbiter came off the stack was pointed down (if I remember correctly).
I think I need to launch it a bunch more times and get it on video each time, instead of getting frustrated after one tumble and packing everything up.
Interesting, if I remember my orbiter worked fairly well in hand tosses, I need to re-trim and repair it though, mover damage. Give the up-scale a toss and see if it works the larger size may make it more easily toss-able. Can't hurt to try I'd wait for a really calm day. With a three axis tumble that could be tricky to tease out, I doubt the orbiter as a whole is too light but that seems to be tumble recovery, check your left-right and vertical CG's verses your original orbiter as well perhaps.
Moving the CG aft will definitely affect trim position on the elevator for a stable glide.
If there was a stable glide before moving the CG then that's true. In this case the glider nose dived before moving the CG back and the removal of nose weight was an attempt to correct it so that it could fly. The result was a tumbling glider, not a stable glide.
That's the plan. As soon as I get a calm sunny afternoon without other plans I'll spend some time throwing it in the back yard and off the deck, making adjustments to see what difference it makes.
From what I can find on the internet about gliders I'm thinking that it just might be too light. Apparently when they say that weight is the enemy of a glider that only goes so far. Unfortunately the only information I can find on gliders is for the little balsa gliders, or similarly shaped planes. Nothing about delta wing gliders like the shuttle. I suppose if I crack the code I can create a page and share what I've found with the world.
BTW, I asked Dr. Zooch for advice when building it and he gave very little, which is understandable because he didn't want to give away too many company secrets. In a follow up PM I asked him if he cared if I shared the files I made for this upscale (there's more to it than simply printing everything at 1.5x) and he never replied. He's logged on since I sent it, so if he hasn't replied to say no then I guess he doesn't care. I still consider the design 100% his and these files are still that design. However, he didn't seem to mind when people shared the wraps to make the shuttle appear more detailed so unless he says otherwise I'll assume he won't care if these are shared too. So if anyone wants the files I altered in order to build a 1.5x version yourself, let me know and I'll share them. Nosecones (4), tyvek, nylon screw, and balsa not included.
No, moving the CG will always affect the trim position. With a CG change of 1/2 inch aft, you very well may have blown through the entire CG range for stable flight, going from extremely nose heavy to way too far aft for the elevators trim position. Now the elevators might be so effective that their full up position is causing the glider to pitch up past critical AoA, stall, and repeat the process as it tumbles down.
That I agree with. But the first time you said it you added "for a stable glide".
My point was that moving the CG on a glider that flies well will require the elevator to be re-trimmed in order to keep flying well. My glider nose dived before, so moving the CG back wouldn't necessarily require the trim to change in order to get a stable glide. It was possible that after removing all that clay the elevator could have been at the correct trim.
Unfortunately it wasn't. Dang it.
I do appreciate the help though. Not attempting to be curmudgeonly or argumentative. I'm just hoping I get this thing to glide correctly someday. I just need some good weather and a few hours of an empty schedule to make any progress.
I'd start in the middle of the back yard where you'll have nice clean air. In undergrad we built hand tossed gliders with about 5 ft wing spans and several guys tried to toss theirs off the parking garage to get more air. This didn't end well for the coyote. The gliders which flew well below when hand tossed got caught in the turbulent air, from the breeze blowing against / through the structure and promptly fell brick like to the concrete below. So the deck may not give you desirable results. A tall ladder in the middle of the yard likely would work.
Gliders in my limited experience are definitely a weight optimization challenge, the shuttle especially so. The astronauts called it a flying brick with good reason.
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