Care for some scotch?

[BABAR]

Practicing on scrap material is a great idea that is unfortunately rarely used.

One problem with the tape technique, I don’t know about longevity and UV resistance. So for a rocket you are gonna want to keep and fly for a few years, maybe you’d be better off with your first idea.

 

[ebruce1361]

Quite true, but I've seen UV yellowing on bare paint, clearcoat, tape, plastic, etc. Honestly, I think there isn't much I can do to minimize discoloration over time other than storing my rockets in a dark closet. While that is certainly practical, I like to hang mine from the ceiling in the house as decor (yes, the wife has approved this), so I anticipate it. Given that A Wee Dram is made from tubes that already have a beige/cream color to them plus the green and gold, I wonder if the discoloration would even be all that out-of-place on it.

 

[ebruce1361]

More progress this weekend!

I noticed I had one tube misaligned with the motor mount assembly, and had to make a choice. Do I roll with it as it is or build a fresh one? Given that I made one centering ring and then used it to make an exact copy, both centering rings have identical spacing. So all four motor tubes were close to perfectly parallel to the body, it's just one of them was closer to the center point than the other three. Since there was no deviation in the angle, I'm sure the rocket would have flown just fine, but I'm picky. So, I whipped up another one.



This motor mount assembly is pretty much identical to the first one, but there are two notable changes. First, there will be two screws running through the bottom centering ring rather than just one in the center to thread nuts onto for motor retention. This is part of why I decided to go for a complete rebuild of the mount assembly; I couldn't get good retention on all four motors with the one central nut with one motor closer to the screw. The Aerotech DMS motors have that sloped area between the neck that meets the base of the motor tube and where the nozzle begins. With all four motors in place, the closer one would stop the nut before it actually made contact with the other three. Again, this would have likely worked just fine as the other three motors would only slide out just a bit at the time of ejection before hitting the nut, but it bothered me. So, I'm waiting for some glue to dry, then I'll measure and drill holes for two screws that will only have to hold down two motors.

The other change to the motor mount assembly is the inclusion of wide rings around the base of the motor tubes. Since Aerotech motors use a flanged case, thrust rings inside the mount are unnecessary. However, all the rockets I have that fly on Aerotech motors are considerably lighter and smaller than A Wee Dram. It might not even be an issue, but I'm worried about the ends of the motor tubes crumpling or ripping under the stress. So, I cut two cores of medical tape rolls in half and slipped them on the tube ends. The fit isn't perfect, so I have a little gap to fill, but I figure that will do a better job transferring the mechanical force of the motors to the bottom centering ring.


Finally, I began the notching of the body tube to accept the fins and rail guides. I used a cordless dremel with a stone tip to grind away the label paper without cutting into the body tube. I poked holes in the body where the rail guides were going so the epoxy could seep through and have more to grab onto. As for the fins, I made the notch in the label but still have yet to cut out the slots for the fin tabs. I was going to do that tonight, but I only have one battery pack for my cordless dremel, and guess what happened?

So, I'll be making those tab slots tomorrow and dry fitting the fins. If all goes well, I'll start gluing them on tomorrow night.

 

[ebruce1361]

With a fresh charge in my dremel battery, I did quite a bit of work last night! I finished the fin notches and glued the fins. Due to the nature of the uneven surfaces between the tube labels and the root edge of the fins, there are tiny gaps in a few places that I will fill with epoxy using a syringe and a tiny applicator tip possibly tonight or tomorrow so the existing glue can cure. I also selected a designated location for my JLA3 to ride in the payload bay above the shots of scotch, and perforated the body tube so there is plenty of ventilation for the altimeter to sense the pressure drop.






Now, THAT looks like a rocket!


There's still quite a bit more to do. I still have to include the motor retaining screws, install the motor mount assembly, drill holes for nose retention pins (I decided to use the bottle corks because of course I did), work out camera locations, drill some vent holes for pressure equalization, and finalize the scotch tape anti-drag-separation setup.

With the work still to be done, I figure it isn't unreasonable to say I will have this finished by the end of next week, if not by the end of this weekend. That puts an estimated maiden flight at next month's Tripoli Tampa club launch, April 18. Here's hoping weather, coronavirus hullabaloo, automobile dependability, and a zillion other factors facilitate our attendance.

 

[Greg Furtman]

Good to know!


One thing I AM a bit worried about as far as deployment binds is my camera mount setup. I want to attach two cameras to this rocket so I can watch the whole flight looking down at the ground and also monitor the parachute during and after deployment. For the parachute view, that can be done with a small as-see-on-tv Cop Cam or this: https://www.amazon.com/gp/product/B07GRRLCYS/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1 (I have both types plus two 808 cameras) mounted in the packing foam at the base of the payload bay or just an 808 camera mounted to the side of the payload bay. As for the descent view, that camera would have to be mounted to the main body (unless I put two 808 cameras on the payload bay, one facing up and the other facing down, but then the ascent would be seen from one camera and the descent from the other, and I'd prefer have one video of the ground and one video of just the parachute). The reason I am concerned about the deployment when it comes to the cameras is I don't want to use tape to attach the cameras since that runs the risk of tearing the label wrap on the tubes. Rather, I'm thinking of drilling four holes in the body to accommodate thin zip-ties that will go through the key ring hole on the 808 camera, and wrap around it. (See ultra fancy low-res MS Paint diagram below)

This way, I don't have to worry as much about the damage tape might do to the label, and the holes double as vents to mitigate pressure separation, but it also means the zip ties will pass into the body tube. I intend to minimize the intrusion by having the actual locking piece of the zip-ties (I'm sure there's a name for that thing) on the outside of the body, but that still leaves me with something for the vitamin bottle to snag on. That is, if I decide to mount the camera(s) further forward than the bottle rests. I suppose I could attach it further down where the edge of the bottle is already ahead of the zip-ties even at its lowest point in the body, but that's an increase in weight in the tail...as well as an increase in drag.

Maybe what I need to do is sim various positions for the camera(s) in openrocket using a short but thick fin to get an idea what they will do to the CG and CP.

@ebruce1361 , I've been thinking about trying one of these cameras. Low profile and the angle of the lens can be changed.

https://www.amazon.com/dp/B07XTPN52...olid=28MCO3MULBK62&psc=1&ref_=lv_ov_lig_dp_it

 

[ebruce1361]

@ebruce1361 , I've been thinking about trying one of these cameras. Low profile and the angle of the lens can be changed.

https://www.amazon.com/dp/B07XTPN52...olid=28MCO3MULBK62&psc=1&ref_=lv_ov_lig_dp_it

WHY DIDN'T I KNOW ABOUT THIS CAMERA SOONER?

I can imagine it wouldn't be too much of a pain to rig up a spring or elastic mechanism to rotate the camera upon separation. Even better would be a linkage on a servo, but that adds a bunch of complexity. Still, this may be a game-changer for my rocket camera collection! The A3 version of this is a zinc alloy to be attached with a magnet and is listed as 5.6 ounces, but the K1 version is almost certainly lighter being plastic.

 

[Greg Furtman]

WHY DIDN'T I KNOW ABOUT THIS CAMERA SOONER?

I can imagine it wouldn't be too much of a pain to rig up a spring or elastic mechanism to rotate the camera upon separation. Even better would be a linkage on a servo, but that adds a bunch of complexity. Still, this may be a game-changer for my rocket camera collection! The A3 version of this is a zinc alloy to be attached with a magnet and is listed as 5.6 ounces, but the K1 version is almost certainly lighter being plastic.

@ebruce1361 Glad I made your day! Always willing to help other people spend their money. I was thinking 2 of these mounted on opposite sides of the rocket body, one pointing down & one pointing sideways to the horizon..

 

[ebruce1361]

Getting closer to the finish line!

This weekend, I did the two things I was dreading the most for this build. Installing the motor mount assembly (I was putting it off because I was being indecisive about the motor retention setup and wanted to make sure there was nothing more I needed to do with the lower body section), and drilling the holes in the body just under the nose cone for the retention pins (since I decided to use the bottle corks, these are BIG holes and I was worried about messing up the body tube).

For the motor retention, I settled on using JB Weld to hold a pair of nuts onto the topside of the bottom centering ring so a bolt can pass through the centering ring and into the nuts and have a washer hold two of the motors. This of course is done on two sides. The only downside to this setup is if the JB Weld were to ever break and the nuts come loose, I'll have a difficult time getting them out and doing a different retention setup, hence why I went with two nuts per bolt, and I slathered the JB Weld on thick.





As for the nose retention, that actually went better than I expected. I determined where I wanted the cork pins to go, and poked a pilot hole with a round file. Then I used an 11/16" spade drill bit to widen the hole and drill down 3/4" in to the construction foam in the nose. From there, I took a 3/4" long scrap of 18mm tube, slipped it into the hole in the nose foam and set it in place with wood glue. The result looks like an elegant take on Frankenstein's monster with the bolts sticking out of his neck, but it makes great use of the corks and keeps the nose from going anywhere! Granted, these corks stick out almost half an inch and are an inch in diameter, so they will create a fair bit of drag on their own, but that doesn't bother me too much. I'll try to sim them in Openrocket and see just how much they affect the CP position, but if it gets dicey, all I have to do is add some weight behind the nose. And with it filled with construction foam, it's pretty easy to just shove some bolts or nails into it and tape them in place to adjust the weight. I might even carve out a slot to incorporate a plastic tube with removable cap so I can open it and add or remove lead shot or BBs as needed.







There is still a little more work to do, as I still haven't made up my mind on camera locations and haven't done anything as yet about possible drag separation as mentioned in previous posts. However, with the drag produced by the nose pins, maybe drag separation is less of a possibility now? I wonder how much of a pain it would be to calculate the drag just from the payload section and compare that to the drag produced from the fins, rail guides, and cameras.

 

[BABAR]

. And with it filled with construction foam, it's pretty easy to just shove some bolts or nails into it and tape them in place to adjust the weight. QUOTE]

Perhaps it has to do with my experience in Iraq around 2004-2005, but nails may be a bad choice. Stick (pun intended) with blunt objects.

Continues to look cool, as expected.

 

[ebruce1361]

Fair point on the nails. Although, if the nose breaks apart enough to release the nails, I'll have a lot more problems to worry about. But should this rocket come in ballistic, I can certainly see how nails embedded into the nose might be a bad idea.

 

[ebruce1361]

Well, that's it! A Wee Dram is complete!

Over the weekend, I made a few final tweaks to the recovery system hardware (substituting heavy zip-ties for metal quick-links to save weight; don't worry, the shock cord still carries all the weight, the zip ties only keep the ends connected, but aren't load-bearing) and added a ring to limit how far down the recovery canister can go. This serves the dual purpose of keeping the can around the parachute rather than it falling away inside the body (the parachute is anchored to the loop in the base of the payload section), and also keeps the entire recovery setup as far forward as possible to prevent CG shift on the pad.



But the biggest bits of work are the addition of the two camera mounts. The mounts aren't all that fancy themselves; they're just four small slots for zip ties to pass through and a larger hole to allow the camera to sit a bit more flush against the body. In these pictures the zip ties look a bit loose because I have them just threaded in enough to hold the camera in place, but I can still remove them for charging without having to cut the ties. They'll be actually tightened for the flight. I also added a band of clear packaging tape to the top of the main body as well as the bottom of the payload section so I can secure it with strips of scotch tape. Although, I'm starting to think I have enough drag in the forward 1/3 of the rocket, that drag separation may not be an issue. I will be performing an under-powered test flight with no payload as the maiden flight, so we'll see what happens! All I need now is a fresh bottle of Speyburn to fill the sample containers!

 

[Greg Furtman]

Nice job. Post when you fly it.

 

[ebruce1361]

Will do! For now, it looks like all the social distancing and self-isolation protocols have been extended for another 30 days, so the April launch is probably scrubbed. Perhaps May? Since we live in Florida, it may be even later since going out to the field in the middle of summer can be absolute torture.

 

[Greg Furtman]

Will do! For now, it looks like all the social distancing and self-isolation protocols have been extended for another 30 days, so the April launch is probably scrubbed. Perhaps May? Since we live in Florida, it may be even later since going out to the field in the middle of summer can be absolute torture.

So what engines do you plan on using? How high will it fly?

 

[ebruce1361]

For the test flight without a payload, I'll cap two of the motor tubes (opposing corners) inside and fly it on two E15-4Ws. Openrocket puts that flight to about 520 ft. For the main flight with the scotch payload, it'll fly on two E15-7Ws (opposing corners) and two E30-7Ts (with ejection charges removed to maximize coast time). Fully loaded, Openrocket says it will hit close to 1500 ft and just about 250mph.

I thought about also loading this with 4x D12-5s, but that only gives me about 350ft with no payload, so that configuration is scrapped.

 

[Greg Furtman]

For the test flight without a payload, I'll cap two of the motor tubes (opposing corners) inside and fly it on two E15-4Ws. Openrocket puts that flight to about 520 ft. For the main flight with the scotch payload, it'll fly on two E15-7Ws (opposing corners) and two E30-7Ts (with ejection charges removed to maximize coast time). Fully loaded, Openrocket says it will hit close to 1500 ft and just about 250mph.

I thought about also loading this with 4x D12-5s, but that only gives me about 350ft with no payload, so that configuration is scrapped.

May your payload land safely! I love a good Scotch.

 

[BABAR]

May your payload land safely! I love a good Scotch.

Now someone has to build the “Bud-Booster”


Sort of reminds me of old Air Force Pilot safety rules

No smoking for 24 hours prior to flight, and no drinking within 100 feet of the aircraft.

 

[ebruce1361]

I ran the design with full payload through Openrocket with two configurations of three motors to simulate the contingency of any one motor failing to start by loading only three motors and adding a mass component inside the motor tube to simulate the failed motor. In either case of an E30 or E15 not starting, I still get a good 1000ft altitude and decent stability. Contingency A is failure of an E15, and Contingency B is failure of an E30.



Even with a full payload, I'd say that this rocket would even work on two motors (haven't simmed that yet). So long as one of the E15s light, I should be alright since I am removing the ejection from the E30s. If only those light, then this will come in ballistic and I will have a very bad day. I wouldn't mind an emergency backup deployment system, but that adds yet more weight and complexity. For now, I'll just run some igniter tests and build a forgiving cluster whip and pray the rocket gods bless my design.

 

[BABAR]

Run that by me again, why remove the ejection from the E30?

 

[ebruce1361]

Run that by me again, why remove the ejection from the E30?

The total burn time from ignition to ejection is longer for the E15s than the E30s by nearly a whole second despite having the same delays. In every simulation I ran with the E30-7s, they ejected before apogee, and the rocket was still moving close to 40mph. By removing their charges and relying on the E15s, I can get an additional 100+ ft of altitude and the deployment happens immediately after apogee, giving me a deployment between 10 and 15 mph.

 

[BABAR]

The total burn time from ignition to ejection is longer for the E15s than the E30s by nearly a whole second despite having the same delays. In every simulation I ran with the E30-7s, they ejected before apogee, and the rocket was still moving close to 40mph. By removing their charges and relying on the E15s, I can get an additional 100+ ft of altitude and the deployment happens immediately after apogee, giving me a deployment between 10 and 15 mph.

I figured it was something like that. What happens with all E15s?

 

[BABAR]

Now someone has to build the “Bud-Booster”
.

Or the “Busch-Master”

Or the “High-Neken “

 

[Joekeyo]

It would be a shame to use anything but SCOTCH tape.

 

[ebruce1361]

I figured it was something like that. What happens with all E15s?

Honestly, I get about 50ft more altitude with the half and half mix. If i went with all E15s, I would certainly have guaranteed ejection, at the expense of a bit of altitude. Plus, I DO love those White Lightning flames. I was thinking of using the E30s in the mix not only for the added thrust, but also to have a combination of white and blue flames in the tail as a nod to the flag of Scotland, but as was discussed further back, the blue flames might not even be visible.

Maybe I should just use the twin E30-7s for the test flight and fly the payload on 4x E15s. That would also eliminate the added complication of removing the ejection charges from the E30s, as well as the possibility of installing the motors in the wrong tubes like I did with my 1:100 Saturn V. Luckily, I designed this rocket to allow sufficient optional configurations that I can still change my mind on the motor setup this late in the game.

 

[ebruce1361]

It would be a shame to use anything but SCOTCH tape.

Indeed! Besides, Scotch is the best tape anyhow.

Off topic, I see your profile lists you in Sun City Center, FL. That's just on the other side of Tampa from me! Whereabouts do you fly?

 

[BABAR]

Honestly, I get about 50ft more altitude with the half and half mix. If i went with all E15s, I would certainly have guaranteed ejection, at the expense of a bit of altitude. Plus, I DO love those White Lightning flames. I was thinking of using the E30s in the mix not only for the added thrust, but also to have a combination of white and blue flames in the tail as a nod to the flag of Scotland, but as was discussed further back, the blue flames might not even be visible.

Maybe I should just use the twin E30-7s for the test flight and fly the payload on 4x E15s. That would also eliminate the added complication of removing the ejection charges from the E30s, as well as the possibility of installing the motors in the wrong tubes like I did with my 1:100 Saturn V. Luckily, I designed this rocket to allow sufficient optional configurations that I can still change my mind on the motor setup this late in the game.

I don’t have experience clustering composites, so hopefully someone else WITH experience can comment on clustering composites WITH motor ejection.

 

[Joekeyo]

[QUOTE="ebruce1361, post: 1981995, member: Off topic, I see your profile lists you in Sun City Center, FL. That's just on the other side of Tampa from me! Whereabouts do you fly?[/QUOTE]

I fly am a member of Tampa Tripoli and fly there. Tripoli is about an hour away, so I occasionally fly at any large field I can find (schools, sports fields, etc. ) using Google maps with the grandkids .

Where do you fly?

 

[cwbullet]

Doing my best not to drink on my day off. Then, I find this thread.

Good thread. Next time I buy scotch, I will have to follow your lead.

 

[ebruce1361]

@Joekeyo

TTRA is the only place my family and I get to fly because there aren't any good fields in our area (Pinellas County), but we don't attend as often as I'd like. The last time we were there was in December, and then May before that. It's possible we've bumped into each other and not even known it!

Keeping in accordance with the current world situation, we aren't planning on going out to fly on our own any time soon, but after all this is over perhaps we could join you sometime for an impromptu day of flying? We've got plenty of smaller "park fliers" that don't get much love because I always have some big project to fly at TTRA. I could even arrange bringing lunch in case you need to be coerced.

 

[Joekeyo]

That would be fun. I am not sure how we PM with this forum. If you know how, PM me and I will provide you with my email address. When you are ready we can set up a date. All of my rockets are LP, so I will just use smaller engines. I also have an air rocket "Sonic Boom" which is good for small fields. I am retired, so my schedule is flexible. I am looking forward to it, whenever it happens.