You know it's going to be fun when the LCO makes everyone stand, ready themselves with bent knees and eyes on the prize!
Fanboy looking forward to more vids and reports!
NSL 2024: A 24" Diameter 1/6th SpaceX Dragon Pad Abort Test
- Thread starter bandman444
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Fanboy looking forward to more vids and reports!
The great thing about the San Louis Valley site is that far far away pad for the big dream boat rockets with really big limits. Get to ride in the TAPS nice truck or ATV out to the pad, just like NASA. Soooo cool. Level 3 space out there for the beautiful cover girl rockets.
jpoehlman
Well-Known Member
1/12 scale test flight 2 was nearly perfect! Video link below.
Improvements over test flight 1 included:
Components were installed in a 3D printed box:
On to the flight, we proved the model is stable! Ignition had a slight delay left to right, but the 1010 rail kept the model vertical. Motor burnout was also not equal, but the model righted itself to the flight path!
The video you have been waiting for: Dragon test flight 2
Landing success for the proof of concept not a high priority for this test flight. There was a successful recovery, but despite a near perfect ejection timing from the D16-4 motors, the parachute did not deploy until the very last possible movement.
We still have a lot to do on the 1/6th scale version to fly at NSL West. Good news though, we're feeling confident in the stability of this odd-rock and have learned a lot in these test flights.
Improvements over test flight 1 included:
- A new model was printed in short order with adjustments to accommodate a 1010 rail for launch guidance.
- 8x D16-4FJ motors all with the same batch number
- ignitor resistance was measured, paired by similar measurements, with pairs spilt on opposite sides of the model
- designed and build high current ignition relay box (details below)
- flown in lite winds
Components were installed in a 3D printed box:
On to the flight, we proved the model is stable! Ignition had a slight delay left to right, but the 1010 rail kept the model vertical. Motor burnout was also not equal, but the model righted itself to the flight path!
The video you have been waiting for: Dragon test flight 2
Landing success for the proof of concept not a high priority for this test flight. There was a successful recovery, but despite a near perfect ejection timing from the D16-4 motors, the parachute did not deploy until the very last possible movement.
We still have a lot to do on the 1/6th scale version to fly at NSL West. Good news though, we're feeling confident in the stability of this odd-rock and have learned a lot in these test flights.
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Looks great, a very cool looking short little cluster model. Looking forward to seeing video of the 1/6th version.
Cheers - mark
Cheers - mark
Gus
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Absolutely wonderful! The model is magnificent but as someone who has spent so much time working with boiler plates, it’s just fantastic to see someone putting in the same kind of effort. Really a treat to be watching this. Keep up the great work.
It looked like one group of motors ignited just a tad early but it made no difference. Great job!
rharshberger
Well-Known Member
Here is the RSO/Launch Directors view.....and with TRF's own Lugnut56 as LCO on the mic.
View attachment 20240413_123152.mp4
View attachment 20240413_123152.mp4
Draggy oddrocs and their need for zero delay. No coast.
jpoehlman
Well-Known Member
Catching up on the build of the 1/6th. We're getting close, but NSL West will happen (Fingers crossed).
After the capsule was fiber glassed, next up building a recovery bay section. We started by making a bulk plate circle out of 1/2 plywood:
The band saw made quick work cutting the circle:
The edge was sanded to the needed 18-degree angle:
Resulting in a well fitted bulk plate into the upper end of the capsule:
Interesting to note the size difference between 1/12th scale and 1/6th scale, it seems more like a 4x difference than 2x:
We acquired Carbon 38mm shipping tubes to use as motor mounts. After some review and consideration, we decided on keeping the full 12" length of the motor tube. With this decision, the motor mount needed to extend through the bulk plate, so holes would be need. Carbon paper was used to mark the landing location of the tube on the bulk plate:
And the drill press was setup with a Forstner bit to bore holes at the needed 22-degree angle:
This netted in a nice home for all 8 motor mount tubes:
to be continued........
After the capsule was fiber glassed, next up building a recovery bay section. We started by making a bulk plate circle out of 1/2 plywood:
The band saw made quick work cutting the circle:
The edge was sanded to the needed 18-degree angle:
Resulting in a well fitted bulk plate into the upper end of the capsule:
Interesting to note the size difference between 1/12th scale and 1/6th scale, it seems more like a 4x difference than 2x:
We acquired Carbon 38mm shipping tubes to use as motor mounts. After some review and consideration, we decided on keeping the full 12" length of the motor tube. With this decision, the motor mount needed to extend through the bulk plate, so holes would be need. Carbon paper was used to mark the landing location of the tube on the bulk plate:
And the drill press was setup with a Forstner bit to bore holes at the needed 22-degree angle:
This netted in a nice home for all 8 motor mount tubes:
to be continued........
jpoehlman
Well-Known Member
Now that we had a bulk plate, it was time to get the rest if the recovery bay built. We cut and fit a piece of 10" tube to use as a recovery bay compartment:
The bulk plate was fitted tightly into the capsule and supported so the tube could be positioned properly and align with the nose cap opening. After initial bonding with 5-minute epoxy, the bulk plate tube assembly was removed for completion. Completion work included fillets on both the inside and outside of the tube and fiberglass reinforcement:
AND coating the inside surfaces with a thin layer of epoxy. A terminal block was also added with stranded CAT-5 cable for the ejection charges :
The nose cone modeling was completed with known dimensions and printed. Tree supports where used to achieve a successful upside down print:
We now had full capsule for the first time and 38mm fiberglass coupler tube to use as a central launch lug:
more to follow in the comming days.........
The bulk plate was fitted tightly into the capsule and supported so the tube could be positioned properly and align with the nose cap opening. After initial bonding with 5-minute epoxy, the bulk plate tube assembly was removed for completion. Completion work included fillets on both the inside and outside of the tube and fiberglass reinforcement:
AND coating the inside surfaces with a thin layer of epoxy. A terminal block was also added with stranded CAT-5 cable for the ejection charges :
The nose cone modeling was completed with known dimensions and printed. Tree supports where used to achieve a successful upside down print:
We now had full capsule for the first time and 38mm fiberglass coupler tube to use as a central launch lug:
more to follow in the comming days.........
Looking good... now once it flies, you will need to pair it with a Falcon 9 booster for it's next flight...
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bandman444
Well-Known Member
Only 33ft of 24inch diameter body tube to add. How hard could it be?
Neutronium95
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I know a guy who was planning on building a 24" Falcon 9. I should put you in touch with him...
Home Depot sells 4' segments of 24" tubing $16 each... so $128 for the length of tubing. Chump change compared to the motors you'll need to get that thing off the ground with the upper stage loaded lol
E: Apparently they're sold elsewhere in 12ft segments, each weighing 60lbs. Assuming a 24" falcon 9 would weigh (conservatively) about 200lbs (33' of that tubing should be like 160-180... but also we need a chute, internal structure, couplers, etc for it to be safe to launch, and add the extra 15lbs for the dragon capsule, and 215lbs converts to about 950N (rounding to 1000 for simple math)....) you'd need something with like 5000N of thrust average to be at the 5:1TWR. That's not even considering how much impulse you need to put it above ground. Depending on where you source the motors and your motor choice, that's gonna be two or more massive motors clustered to get the needed thrust, so somewhere over $1k for the motors alone. Quite a project according to my napkin math lol
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terryg
Well-Known Member
Not neccesarily, you would only need to have enough power to get it to enough alititude to simulate a CATO and then activate the PAD abort system......
Why simulate a CATO when you could pack a huge cluster of Estes E-motors into that diameter and practically guarantee one.
(I've not actually had an Estes E CATO yet myself, but with an upcoming flight on twelve of them, that streak may well be living on borrowed time.)
bandman444
Well-Known Member
Way ahead of you.
rharshberger
Well-Known Member
Just make sure all of them are the same ID/OD, sonotubes are designed to nest two in one so a 24" can be either a nominal ID or OD so two nest together for shipping.
jpoehlman
Well-Known Member
No dragon would be complete without a trunk, right? Ours will have a trunk too. The initial build thought was to simply add a layer of fiberglass to the 24 - inch sonotube. The sonotube weighted 9 lbs on it's own and would have added an excessive weight to the wrong / aft end of the dragon given the relatively light weight of the capsule. Bryce had the bright idea: "Why not use the sonotube as a mandrel for a fiber glass tube?", and so began the making of a fiberglass layup tube.
We started by with a layer of mylar as a release layer over the sonotube:
We landed on doing 3 layers of fiberglass cloth and began mixing west systems laminating epoxy and spreading on the tube, laying the cloth over the wetted-out surface and repeat. No pictures during the process as all hands where needed for mixing, pouring, spreading, laying glasses, etc. We did have a little forced break after finding mixing a bit too large of a batch and exceeding the pot life for the last several oz of the batch. Bryce's thumbs down to the gelled epoxy on the table and in the syringe:
This made for very sad rocket builders:
After the final layer of fiberglass cloth was added, another layer of mylar release film was placed. At this point, the layup was complete and set aside for curing with a ring placed inside the tube to keep it in circular shape:
After curing, the fiberglass tube slid off the mandrel with easy:
The ends of the tube were trimmed with a Dremel. With only 3 layers of fiberglass, the tube had a lot of flexibility. Fortunately the we still had the sonotube with just the right fit. A 6 inch ring was cut for the lower part of the tube, and a 1 inch ring for the upper. The 1 inch upper ring was used to as part of the bonding surface for the trunk to capsule interface:
Additional fiberglass layup was used to ensure the capsule and trunk have a tight bond:
The completed weight of the trunk was 4 lbs, a significant weight savings.
Next up, Fins..........
We started by with a layer of mylar as a release layer over the sonotube:
We landed on doing 3 layers of fiberglass cloth and began mixing west systems laminating epoxy and spreading on the tube, laying the cloth over the wetted-out surface and repeat. No pictures during the process as all hands where needed for mixing, pouring, spreading, laying glasses, etc. We did have a little forced break after finding mixing a bit too large of a batch and exceeding the pot life for the last several oz of the batch. Bryce's thumbs down to the gelled epoxy on the table and in the syringe:
This made for very sad rocket builders:
After the final layer of fiberglass cloth was added, another layer of mylar release film was placed. At this point, the layup was complete and set aside for curing with a ring placed inside the tube to keep it in circular shape:
After curing, the fiberglass tube slid off the mandrel with easy:
The ends of the tube were trimmed with a Dremel. With only 3 layers of fiberglass, the tube had a lot of flexibility. Fortunately the we still had the sonotube with just the right fit. A 6 inch ring was cut for the lower part of the tube, and a 1 inch ring for the upper. The 1 inch upper ring was used to as part of the bonding surface for the trunk to capsule interface:
Additional fiberglass layup was used to ensure the capsule and trunk have a tight bond:
The completed weight of the trunk was 4 lbs, a significant weight savings.
Next up, Fins..........
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jpoehlman
Well-Known Member
Fins, we need fins for this dragon. Following the theme of light weight yet strong construction, honeycomb would be a great choice!
We just happen to have some 3/8 inch Nomex honeycomb, so begins another fiberglassing session........
The layers of this layup where:
3/4 MDF panel
Mylar release film
2 layers of fiberglass cloth - very wet for bonding to honeycomb
nomex honeycomb
2 layers of fiberglass cloth - very wet for bonding to honeycomb
Mylar release film
3/4 MDF panel
All sandwich together and placed in a vacuum bag and sucked together.
wetting out the first layer of fiberglass:
Placing the Nomex honeycomb:
Followed by flass over the top:
The entire layup was placed in a vacuum bag and lefter under vacuum for several hours:
The net result was a very strong yet light weight panel. A paper fin template was created and used to determine exact layout and trace the 4 fins onto the panel. The fins where cut out using the bandsaw:
wood firing strips were added to the edge of the fins to:
A round over router bit was used to trim and shape the wood edge of the fins:
the finished fins:
The forward tip of the fins were trimmed with a miter saw for fitment of the 3D printer fairing. 5 minute epoxy was used to afix the fin and fairing to the trunk section:
Additional wood stripes were cut for the fillet / fairings and epoxied in place. This added significant strength and rigidity to the fin attachments and completed the scale look of the dragon:
After a little sanding, it was paint time:
Painting summoned the PNW rain gods with sprinkles starting as soon as the first can of paint was exhausted:
It's almost time to load this for transport to NSL West. Packing and flight check list are in the works.
This thing is going to fly! Looking forward to seeing you all next weekend at NSL. If you are at NSL, stop by to say hi. We'll have markers on hand if you want to add your signature or well wishes to this project. Look for the rocket trailer with a 4 foot tall dragon near by.
We just happen to have some 3/8 inch Nomex honeycomb, so begins another fiberglassing session........
The layers of this layup where:
3/4 MDF panel
Mylar release film
2 layers of fiberglass cloth - very wet for bonding to honeycomb
nomex honeycomb
2 layers of fiberglass cloth - very wet for bonding to honeycomb
Mylar release film
3/4 MDF panel
All sandwich together and placed in a vacuum bag and sucked together.
wetting out the first layer of fiberglass:
Placing the Nomex honeycomb:
Followed by flass over the top:
The entire layup was placed in a vacuum bag and lefter under vacuum for several hours:
The net result was a very strong yet light weight panel. A paper fin template was created and used to determine exact layout and trace the 4 fins onto the panel. The fins where cut out using the bandsaw:
wood firing strips were added to the edge of the fins to:
A round over router bit was used to trim and shape the wood edge of the fins:
the finished fins:
The forward tip of the fins were trimmed with a miter saw for fitment of the 3D printer fairing. 5 minute epoxy was used to afix the fin and fairing to the trunk section:
Additional wood stripes were cut for the fillet / fairings and epoxied in place. This added significant strength and rigidity to the fin attachments and completed the scale look of the dragon:
After a little sanding, it was paint time:
Painting summoned the PNW rain gods with sprinkles starting as soon as the first can of paint was exhausted:
It's almost time to load this for transport to NSL West. Packing and flight check list are in the works.
This thing is going to fly! Looking forward to seeing you all next weekend at NSL. If you are at NSL, stop by to say hi. We'll have markers on hand if you want to add your signature or well wishes to this project. Look for the rocket trailer with a 4 foot tall dragon near by.
Sharon and I will be stopping by to say Hi, with a little something from Robert at AMW.
TLAR, but ...
Did y'all have to use the Base Drag Hack to check your Stability ?
(
ducks )
-- kjh( wishing I could be there )
Did y'all have to use the Base Drag Hack to check your Stability ?
(
ducks )-- kjh( wishing I could be there )
bandman444
Well-Known Member
We did. Then followed up with a subscale flight demo that did demonstrate stability. If the “base drag hack” was completely made up, then some other mechanism was providing the stability for this and other similar models.TLAR, but ...
Did y'all have to use the Base Drag Hack to check your Stability ?
(
-- kjh( wishing I could be there )
Either way, I am confident in the design flying straight with a CG above the nozzle plane and with all motor lit.
Thanks for your post. It makes me curious if there could be validity to your claim, and if the base drag hack is indeed false, how do rockets with poor Barrowman equation performance consistently fly safe.
boatgeek
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Not to derail the discussion, but I suspect that the BDH is more or less valid for rockets where the shape like a cone where the airflow is directed outward at or near the end of the rocket. For more normal shapes, a 10% stability margin is probably fine. In this case, I'd guess that the flow doesn't have time to reattach to the skirt.
Cue my favorite German joke:
A senior German automotive engineer is touring a newly redesigned Big Three plant in Michigan. He's very quiet through the tour, so eventually the guide asks him what he thinks of the operation. "It's all well and good in practice," he said, "But it will never work in theory!"
How does a fat, stubby, eight canted tractor motor oddroc fly? WITCHCRAFT! Do you believe in magic?
All the site rocket scientists are talking stability, tearing down proof of stability tools like swing tests, computer simulation, cardboard cut outs, sub scale models, home made wind tunnels and on and on.
In the meantime I am super focused on getting all the motors to light and come up to pressure in unison, just enough to keep the oddroc abomination going straight up. All connections clean and secure! Calm conditions...YIPPEE! Push that button!
I know the only reason I got a pad assignment on the far, far, far away pad is that the crowd was ready for something completely different, accompanied with the excitement of a potential NASCAR style crash. Never admitted but true.
How do the good ole boys fly anvils with black powder, a fuse and some bacon grease? Show me the Science!
With all the weight up front I find a modicum of solace in the Pendulum Falicy. It was good for a thousand years and that ain't bad. Ancient Chinese Secrets!
You have stepped out of the 3-4FNC safety box. Good luck!
All the site rocket scientists are talking stability, tearing down proof of stability tools like swing tests, computer simulation, cardboard cut outs, sub scale models, home made wind tunnels and on and on.
In the meantime I am super focused on getting all the motors to light and come up to pressure in unison, just enough to keep the oddroc abomination going straight up. All connections clean and secure! Calm conditions...YIPPEE! Push that button!
I know the only reason I got a pad assignment on the far, far, far away pad is that the crowd was ready for something completely different, accompanied with the excitement of a potential NASCAR style crash. Never admitted but true.
How do the good ole boys fly anvils with black powder, a fuse and some bacon grease? Show me the Science!
With all the weight up front I find a modicum of solace in the Pendulum Falicy. It was good for a thousand years and that ain't bad. Ancient Chinese Secrets!
You have stepped out of the 3-4FNC safety box. Good luck!
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