3/4 Mercury Redstone
- Thread starter Feckless Counsel
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Coop
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Like the rest of TRF, I've been enjoying this build thread immensely, and thought it was an insane project in the very best way since I first learned of it. I would never state that I know what the world needs at any given point in time, but I'm pretty extra-special sure that an amateur-built, 63ish foot tall rocket weighing almost half a ton flying to 1km would be near the top of the list, regardless.
Considering the size of the parachutes necessary to retrieve each component, and the weight of the chutes, weight of the body sections, and force necessary to separate these, there was some question as to whether the deployment bags were up to the task. Tom C asked if I might have time to take a look at them to see if I could, perhaps, beef them up a bit. Of particular concern were the bags for the sustainer and booster --the largest sections. These would have large ejection charges, carry the heaviest chutes, and be exposed to the most force during the initial deployment sequence. The fear was that the bag may rip, leave the chute contained, unable to unfurl. Understandably, this is a scenario that should be mitigated if at all possible.
The first bag I received was rather straightforward in its needs--it had seen some use, and the top loop was starting to pull away from the fabric. The top loop was comprised of two layers of Nomex, serged together to form a strip 1" wide by 7" long. On the interior of the bag, there was an identical loop, and these were sewn together through the bag itself. It appeared that, during initial assembly, the thread that was used was B thread... it has a strength rating of about 12lb/ stitch, and they ran around 10 stitches per inch.
The loops that were replaced.
In their place, I cut some Nylon webbing from stock, and sewed that in. This is the same kind of 1" webbing one often sees in use as shock cords.
It's a good deal thicker, and quite a bit stronger than the fabric. The length of webbing was a bit longer than the original, to give the bases more surface area--and one was sewn through the other. In addition, I used F thread --which requires needles that are generally past that which a domestic sewing machine can think of handling. It is quite a bit beefier and stronger than the original. Like the first time, it was sewn in thrice-over. I used the same thread to replace the top of the bag, and sew the bag back up. This was one of the sewing projects that took forever to take apart, but went together rather quickly. I was pleased enough with the result and returned it to the MR crew.
A few days later, I received the two large bags. These are the ones that required additional attention from the ejection charge and (apologies for the Clockwork Orange reference, here, but I gotta...) ultraviolence at ejection. The same type of loops were at the top. Given the ejection charges for these sections, however, TK was chosen over Nylon for the outer (exposed) loops. I had a long shock cord lying around I can't afford to fly at the moment, so it gave up a couple feet. It won't be missed --I use that one with large streamers.
1/2" Tubular Kevlar
I remembered that I might want to take photos of the process on these two, so I actually got a couple while work was underway. The overall process was essentially the same as previously described, with an extra step or two. The Nylon webbing was sewn in to the interior aspect of the bag, with the TK exposed --these are sewn into each other with Kevlar F thread, at about 30 lb/stitch, and gone over a couple of times. Then the top of the bag is reinstalled.
First, a straight stitch is used to join the pieces together. Then, a 3mm wide zigzag goes over the original straight stitch line.
After this, lighter-grade webbing is sewn over each seam as I do with the satin bias tape on my chutes --just.... on a much heavier, and much larger scale.
Very little weight was added, and the bags are now set to be stuffed with recovery devices that use a reference area in, I believe, "acreage."
It is wonderful to contribute to this project--I'm thrilled to have done so. I cannot thank Feckless Council enough for the opportunity, as well as Tom C And JL --all of whom contributed greatly to the input for my small contribution.
Later!
--Coop
Considering the size of the parachutes necessary to retrieve each component, and the weight of the chutes, weight of the body sections, and force necessary to separate these, there was some question as to whether the deployment bags were up to the task. Tom C asked if I might have time to take a look at them to see if I could, perhaps, beef them up a bit. Of particular concern were the bags for the sustainer and booster --the largest sections. These would have large ejection charges, carry the heaviest chutes, and be exposed to the most force during the initial deployment sequence. The fear was that the bag may rip, leave the chute contained, unable to unfurl. Understandably, this is a scenario that should be mitigated if at all possible.
The first bag I received was rather straightforward in its needs--it had seen some use, and the top loop was starting to pull away from the fabric. The top loop was comprised of two layers of Nomex, serged together to form a strip 1" wide by 7" long. On the interior of the bag, there was an identical loop, and these were sewn together through the bag itself. It appeared that, during initial assembly, the thread that was used was B thread... it has a strength rating of about 12lb/ stitch, and they ran around 10 stitches per inch.
The loops that were replaced.
In their place, I cut some Nylon webbing from stock, and sewed that in. This is the same kind of 1" webbing one often sees in use as shock cords.
It's a good deal thicker, and quite a bit stronger than the fabric. The length of webbing was a bit longer than the original, to give the bases more surface area--and one was sewn through the other. In addition, I used F thread --which requires needles that are generally past that which a domestic sewing machine can think of handling. It is quite a bit beefier and stronger than the original. Like the first time, it was sewn in thrice-over. I used the same thread to replace the top of the bag, and sew the bag back up. This was one of the sewing projects that took forever to take apart, but went together rather quickly. I was pleased enough with the result and returned it to the MR crew.
A few days later, I received the two large bags. These are the ones that required additional attention from the ejection charge and (apologies for the Clockwork Orange reference, here, but I gotta...) ultraviolence at ejection. The same type of loops were at the top. Given the ejection charges for these sections, however, TK was chosen over Nylon for the outer (exposed) loops. I had a long shock cord lying around I can't afford to fly at the moment, so it gave up a couple feet. It won't be missed --I use that one with large streamers.
1/2" Tubular Kevlar
I remembered that I might want to take photos of the process on these two, so I actually got a couple while work was underway. The overall process was essentially the same as previously described, with an extra step or two. The Nylon webbing was sewn in to the interior aspect of the bag, with the TK exposed --these are sewn into each other with Kevlar F thread, at about 30 lb/stitch, and gone over a couple of times. Then the top of the bag is reinstalled.
First, a straight stitch is used to join the pieces together. Then, a 3mm wide zigzag goes over the original straight stitch line.
After this, lighter-grade webbing is sewn over each seam as I do with the satin bias tape on my chutes --just.... on a much heavier, and much larger scale.
Very little weight was added, and the bags are now set to be stuffed with recovery devices that use a reference area in, I believe, "acreage."
It is wonderful to contribute to this project--I'm thrilled to have done so. I cannot thank Feckless Council enough for the opportunity, as well as Tom C And JL --all of whom contributed greatly to the input for my small contribution.
Later!
--Coop
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Coop
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Thanks so much!
I made one or two Higgs flights since we moved there last fall, but have missed a couple due to work schedule--on night shift now, and often switch up to do a 24-hr shift, so I have to commute fewer days per month--and the schedule with the kids has been a little nuts --read: "bonkers" with their activities.
Later!
--Coop
I made one or two Higgs flights since we moved there last fall, but have missed a couple due to work schedule--on night shift now, and often switch up to do a 24-hr shift, so I have to commute fewer days per month--and the schedule with the kids has been a little nuts --read: "bonkers" with their activities.
Later!
--Coop
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Coop,
Thanks for the update. No way those attachments will rip.
TRF,
Twenty feet tall is the most we can stack at our facility. So we have stacked pieces in pairs. Each pair is marked for orientation, drilled through longerons and cross pinned. All pieces are now test fit an drilled.
Today we crated half the pieces. Tomorrow we crate the balance. Wednesday we ship to paint and decoration.
Motor work has progressed. Metallic pieces are being machined. Propellant grains are cast. Concerns for our motor design come from TRFs most respected motor designers. So we are taking them seriously and conducting a full scale ground test. We hope to conduct that test either 3 March or 11 March.
If all that goes well I believe we will launch first week of April.
Feckless Counsel
Thanks for the update. No way those attachments will rip.
TRF,
Twenty feet tall is the most we can stack at our facility. So we have stacked pieces in pairs. Each pair is marked for orientation, drilled through longerons and cross pinned. All pieces are now test fit an drilled.
Today we crated half the pieces. Tomorrow we crate the balance. Wednesday we ship to paint and decoration.
Motor work has progressed. Metallic pieces are being machined. Propellant grains are cast. Concerns for our motor design come from TRFs most respected motor designers. So we are taking them seriously and conducting a full scale ground test. We hope to conduct that test either 3 March or 11 March.
If all that goes well I believe we will launch first week of April.
Feckless Counsel
When do you expect the paint to be completed?
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Fred,
We loaded the dry van tonight. It will be picked up tomorrow, 28 February. Delivery to paint is Friday, 1 March. Problem is our paint guy goes to a weeks vacation that day. Painting isnt really underway until 12 March. Decoration will be complete something like 18 March depending on how relaxing his vacation.
Fortunately this thing is substantially white. We plan on using DuraLaq nitrocellulose lacquer. That should build fast and dry quick. I estimate 3 hours preparation, 6 hours painting and 12 hours decorating.
Feckless Counsel
We loaded the dry van tonight. It will be picked up tomorrow, 28 February. Delivery to paint is Friday, 1 March. Problem is our paint guy goes to a weeks vacation that day. Painting isnt really underway until 12 March. Decoration will be complete something like 18 March depending on how relaxing his vacation.
Fortunately this thing is substantially white. We plan on using DuraLaq nitrocellulose lacquer. That should build fast and dry quick. I estimate 3 hours preparation, 6 hours painting and 12 hours decorating.
Feckless Counsel
Exciting times 
. I bet you can't wait to see it in its true colors.
. I bet you can't wait to see it in its true colors.
Nytrunner
Pop lugs, not drugs
No "Nathan-finish" for this rocket lol.
I guess you can forego a mirror finish in order to have it fly this decade!
I guess you can forego a mirror finish in order to have it fly this decade!
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TRF,
The rocket arrived to paint without damage. We were very concerned as weather that day included 60MPH gusts. Trees were down. There were widespread power outages. There was us moving 6x8 foot cylinders. Fortunately the paint booth is huge with doors opening right onto the loading dock. Driver was able to back against the door. Wind was not a factor.
When I say huge I mean YUGE. The entire project fits in the paint booth with plenty of working room. Thing is probably 20x30 with a 20 foot ceiling.
Now we are working on the test motor. That is a 20% Q-impulse white thunder motor targeting 6,000 pounds of thrust over 4 seconds. Grains are cast. Case components are near complete. Data acquisition is on schedule including chamber pressure, thrust, 2 channels of strain, 8 channels of temperature, sound pressure level and high speed video. Hopefully we can test fire on 11 March.
Feckless Counsel
The rocket arrived to paint without damage. We were very concerned as weather that day included 60MPH gusts. Trees were down. There were widespread power outages. There was us moving 6x8 foot cylinders. Fortunately the paint booth is huge with doors opening right onto the loading dock. Driver was able to back against the door. Wind was not a factor.
When I say huge I mean YUGE. The entire project fits in the paint booth with plenty of working room. Thing is probably 20x30 with a 20 foot ceiling.
Now we are working on the test motor. That is a 20% Q-impulse white thunder motor targeting 6,000 pounds of thrust over 4 seconds. Grains are cast. Case components are near complete. Data acquisition is on schedule including chamber pressure, thrust, 2 channels of strain, 8 channels of temperature, sound pressure level and high speed video. Hopefully we can test fire on 11 March.
Feckless Counsel
Nytrunner
Pop lugs, not drugs
Those are some big cores,
I'm so excited!!! I've been asked to hold the igniter in the motor during the launch. I can fit my arm all the way up there!
(This is a joke -- for the humor-challenged.)
blackbrandt
That Darn College Student
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Why such large cores?
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High thrust, short burn.
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BlackBrandt,
John is, as usual, spot on. Our goal is 6,000 pounds thrust and 4 seconds burn. That is about 106,000N-s or a junior Q-motor. John predicted just under that performance from the picture of our grains. Very impressive.
Our TAP wants this project to leap off the pad fast and straight up. We are coming in a little heavy at 1,000 pounds pad-weight. To satisfy the TAP we are targeting 6:1 ratio in thrust. That’s where the 6,000 pounds thrust goal originates.
The radius of Higgs’ Farm is about 3,000 feet. We don’t want to fly higher than that radius or dual deploy might be required. The forces of secondary deployment are near our design limit. Better to stay low and pop chutes about apogee. So let’s keep the seconds of Newtons inside the field. From there Tom C and COOP will bring us home.
Feckless Counsel
John is, as usual, spot on. Our goal is 6,000 pounds thrust and 4 seconds burn. That is about 106,000N-s or a junior Q-motor. John predicted just under that performance from the picture of our grains. Very impressive.
Our TAP wants this project to leap off the pad fast and straight up. We are coming in a little heavy at 1,000 pounds pad-weight. To satisfy the TAP we are targeting 6:1 ratio in thrust. That’s where the 6,000 pounds thrust goal originates.
The radius of Higgs’ Farm is about 3,000 feet. We don’t want to fly higher than that radius or dual deploy might be required. The forces of secondary deployment are near our design limit. Better to stay low and pop chutes about apogee. So let’s keep the seconds of Newtons inside the field. From there Tom C and COOP will bring us home.
Feckless Counsel
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Bat-mite,
The bet was you couldn't do it twice.
Feckless
The bet was you couldn't do it twice.
Feckless
Nathan
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I will definitely not be helping them wetsand and polish the finish on this rocket, which according to my calculation has about 850 sq ft of surface area. :eyepop:
Yeah, I think they want to launch this year. :wink:
Why not? I have two arms .... :grin:
Sooner Boomer
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What do you use to light that thing off? An I motor sparky?
I'm guessing a large igniter, with several pyrogen pellets glued to the top of the top grain.
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Not as crazy as it sounds!
No guessing required. Just look at how professional motors of this size have been started quickly for many years. Heat flux + pressure threshold. Due to the large core, getting it up to the pressure threshold quickly is a challenge we don't typically have in regular grain geometries. You cannot rely on self-pressurization from the initial start of the top grain of the motor. Putting enough heat flux into the top grain to fill the motor could damage the grain.
More practical details would probably have to be in the research forum. A rough calculation gives about 100g of 'good' igniter mass, distributed to light as much of the pyrogen surface area as quickly as possible. But, lightly contained to not puke out the nozzle before doing its job.
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You still have them beat on the N-secs per pound and N-secs per team member.
That's a good spin. :grin:
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