Prepping filament wound fiberglass.

[DeltaVee]

I was looking at the Composite Warehouse full scale HV-Arcas... and looking and looking. I've liked this particular subject ever since I put the Aerotech HV-Arcas together.... and it's one of my most flown rockets. I decided I want to do an L2 project so I thought this would fit the bill. Well someone here in my house noticed what I was looking at and guess what arrived just in time for my birthday... The missus knew I was jonesing over that kit and she went and did something about it!

So now I have to start working on it. I'm not planning on rushing it and expect to take quite a while to finish it... I was a bit concerned about not having worked with fiberglass but others in the club have been very encouraging (knowing I was thinking about this kit etc.) going so far as to indicate that I possess enough skills to actually work it successfully! So be it.

So here is the first concern prior to getting started... A nice coating of powdered release agent seems to need cleaning off... what to use? I could use a power washer with a low pressure tip which is tempting.. but seriously what does one use to clean the parts off? Water and detergent perhaps? A solvent like Isopropyl? Does it matter? I assume the material is impervious to water! I read somewhere on TRF someone used the bathtub... but as I would like to stay married... might not be the best option.

I have gloves and a respirator and the statements I've seen regarding protecting ones' self isn't falling on deaf ears at least (I need to do a major cleanout of my work area in the garage...) so it's clear I can't mess with this material in the house!

Advice at how extensively (and where) to scuff the parts, tips about drilling holes in this stuff and so on would also be greatly appreciated!

Thanks in advance!

 

[bobbyg23]

I was looking at the Composite Warehouse full scale HV-Arcas... and looking and looking. I've liked this particular subject ever since I put the Aerotech HV-Arcas together.... and it's one of my most flown rockets. I decided I want to do an L2 project so I thought this would fit the bill. Well someone here in my house noticed what I was looking at and guess what arrived just in time for my birthday... The missus knew I was jonesing over that kit and she went and did something about it!

So now I have to start working on it. I'm not planning on rushing it and expect to take quite a while to finish it... I was a bit concerned about not having worked with fiberglass but others in the club have been very encouraging (knowing I was thinking about this kit etc.) going so far as to indicate that I possess enough skills to actually successfully! So be it.

So here is the first concern prior to getting started... A nice coating of powdered release agent seems to need cleaning off... what to use? I could use a power washer with a low pressure tip which is tempting.. but seriously what does one use to clean the parts off? Water and detergent perhaps? A solvent like Isopropyl? Does it matter? I assume the material is impervious to water! I read somewhere on TRF someone used the bathtub... but as I would like to stay married... might not be the best option.

I have gloves and a respirator and the statements I've seen regarding protecting ones' self isn't falling on deaf ears at least (I need to do a major cleanout of my work area in the garage...) so it's clear I can't mess with this material in the house!

Advice at how extensively (and where) to scuff the parts would also be greatly appreciated!

Thanks in advance!

Give it a nice bath with dawn dish soap to get rid of any release agent and dust.

 

[DeltaVee]

Nice touch with the candles! The release agent didn't pose a problem with the drain? Im not sure the main airframe will fit in the tub! (I'll wait until the missus is out and about!)

 

[bobbyg23]

Nice touch with the candles! The release agent didn't pose a problem with the drain? Im not sure the main airframe will fit in the tub! (I'll wait until the missus is out and about!)

There is really not much to wash off, so it is no problem doing it in the tub.

 

[mtnmanak]

Bobbyg23 has the right of it - scrub all the parts with dish soap and rinse thoroughly.

Sand every thing with 220 grit. For a 4.5" kit, you can grab your random orbital palm sander and make your life easier. Also, sand the inside of the tubes where epoxy will be used (fin can, inside the switch band, etc.). Basically, you need to sand anyplace that is going to touch paint or adhesives. All you are doing is trying to "take the shine off" - don't sand to the point of breaking any of the fibers.

Wash the parts again to get all that dust off and you are good to go.

You mentioned PPE and dust management in your OP - I highly recommend you do the sanding outside, if you can. Once you get FG dust inside, especially on fabric/rugs/etc - it is really difficult to get out. If you do have to sand indoors, I do not recommend using power tools - they generate a huge amount of airborne dust.

 

[JackC]

You can also use denatured alcohol on a rag to wipe the release agent off. Works like a charm.

As for the sanding, everything mtnmanak said is on the nose.

I have the Composite Warehouse HV Arcas and it’s a great rocket. However, you’ll need a big L2 motor to fly it safely. Mine is 18 pounds without motor, so we’re talking a 54 mm L motor or a 75mm big K or L motor. So, please keep that in mind for your choice of a rocket. My kid did his L2 with a 4.5 inch FWFG IQSY Tomahawk, a similar size to the Arcas. His rocket is 20 pounds without motor and he calculated that the CSR L730 54mm motor would provide a safe Cert. Flight. It flew to 5,200 feet and was safe but was definitely a little underpowered. The next time he used an Aerotech 75mm L motor and achieved a straight flight to 10,000 feet with authority.

I would also say my Arcas is a bit underpowered with most 54mm motors, so I tend to fly her with 75mm L and M motors.

 

[JackC]

As for drilling, just use a good 18 volt drill with a good set of drill bits (titanium works great). Make sure you drill straight down into the material because the bit can slide on the fiberglass if you don’t apply enough pressure.

 

[OverTheTop]

Useful link here:
https://www.rocketryforum.com/threa...our-government-doesnt-want-you-to-know.58389/
Personally, after the major washing, just before bonding I wipe the fiberglass down with MIBK. If you are going to do this wear PPE (glasses, gloves) and do it in a well-ventilated area.

 

[DeltaVee]

You can also use denatured alcohol on a rag to wipe the release agent off. Works like a charm.

As for the sanding, everything mtnmanak said is on the nose.

I have the Composite Warehouse HV Arcas and it’s a great rocket. However, you’ll need a big L2 motor to fly it safely. Mine is 18 pounds without motor, so we’re talking a 54 mm L motor or a 75mm big K or L motor. So, please keep that in mind for your choice of a rocket. My kid did his L2 with a 4.5 inch FWFG IQSY Tomahawk, a similar size to the Arcas. His rocket is 20 pounds without motor and he calculated that the CSR L730 54mm motor would provide a safe Cert. Flight. It flew to 5,200 feet and was safe but was definitely a little underpowered. The next time he used an Aerotech 75mm L motor and achieved a straight flight to 10,000 feet with authority.

I would also say my Arcas is a bit underpowered with most 54mm motors, so I tend to fly her with 75mm L and M motors.

The weight you have is quite interesting since the advertised weight of the HV-Arcas is 14 lbs. I've weighed the individual components so far, and estimated a few items and they total roughly 11 lbs (less than the 14 quote on the CW website)... of course that is without electronics, paint epoxy and metal linkages/swivels and various other guts... I'm working on getting a good OpenRocket representation of this and I have yet to estimate the of all the above...which I know can add up to quite a bit. That said, if I can keep it to the mid teens (using an overall mass 15 lbs say) then in principle, something like an Aerotech J520 *should* give it an off-the-rail (8 feet for our pads) speed of about 50 mph to an altitude of about 1200 feet... which I kind of like since I'd rather not send it up all that high... but maybe that's safer. BUT that's only if I can keep the weight down so that it comes out to the 15 lb figure... which I don't know for sure if that would be feasible. Clearly motor choice will depend on the final form... I'm NOT going to fly something iffy on our field... and our LCO/RSO wouldn't let me anyway! If it gets heavy enough then I'd go with a K or L.

 

[Ez2cDave]

Is the song "Splish-Splash" playing, while it's in the tub ? LOL !



Dave F.

 

[JackC]

The weight you have is quite interesting since the advertised weight of the HV-Arcas is 14 lbs. I've weighed the individual components so far, and estimated a few items and they total roughly 11 lbs (less than the 14 quote on the CW website)... of course that is without electronics, paint epoxy and metal linkages/swivels and various other guts... I'm working on getting a good OpenRocket representation of this and I have yet to estimate the of all the above...which I know can add up to quite a bit. That said, if I can keep it to the mid teens (using an overall mass 15 lbs say) then in principle, something like an Aerotech J520 *should* give it an off-the-rail (8 feet for our pads) speed of about 50 mph to an altitude of about 1200 feet... which I kind of like since I'd rather not send it up all that high... but maybe that's safer. BUT that's only if I can keep the weight down so that it comes out to the 15 lb figure... which I don't know for sure if that would be feasible. Clearly motor choice will depend on the final form... I'm NOT going to fly something iffy on our field... and our LCO/RSO wouldn't let me anyway! If it gets heavy enough then I'd go with a K or L.

Some of that weight is SkyAngle chute and very robust recovery hardware and shock cord. Also, you need to keep the weight of your motor case and propellant in mind for your safety calculations, too. In my case, I tend to build my rockets like a tank more for longevity purposes.

 

[mtnmanak]

I usually end up with a dry weight of about 40%-50% more than the kit makers suggest.

For example, I am currently working on one of Curtis' (Composite Warehouse) 9" MegaBusters. He lists the built weight as 52 pounds. I estimate the dry weight for that rocket will be somewhere around 75 pounds. Heck, the booster alone built out to almost 40 pounds.

In order to shed weight, you would need to invest in some expensive parts like lightweight kevlar shock cords, ultra-light parachutes, exotic adhesives, etc. That is too much money for me. For example, for that 9" rocket mentioned above, I could switch out the Cert 3 XXL parachute (4 pounds) with a Fruity Chute 168" Ultra Light Iris (2 pounds) and get a 50% weight reduction in my main parachute, but the Cert 3 costs about $200 on sale, whereas the Ultra Light Iris costs almost $1200.

In rockets, as with electronics, you always have to adjudicate the "performance - lightweight - cheap" triangle. You can only have 2. If I am building minimum diameter for ultimate altitude, I go with lightweight performance, but all other builds default to cheap performance.

 

[DeltaVee]

I usually end up with a dry weight of about 40%-50% more than the kit makers suggest.

For example, I am currently working on one of Curtis' (Composite Warehouse) 9" MegaBusters. He lists the built weight as 52 pounds. I estimate the dry weight for that rocket will be somewhere around 75 pounds. Heck, the booster alone built out to almost 40 pounds.

In order to shed weight, you would need to invest in some expensive parts like lightweight kevlar shock cords, ultra-light parachutes, exotic adhesives, etc. That is too much money for me. For example, for that 9" rocket mentioned above, I could switch out the Cert 3 XXL parachute (4 pounds) with a Fruity Chute 168" Ultra Light Iris (2 pounds) and get a 50% weight reduction in my main parachute, but the Cert 3 costs about $200 on sale, whereas the Ultra Light Iris costs almost $1200.

In rockets, as with electronics, you always have to adjudicate the "performance - lightweight - cheap" triangle. You can only have 2. If I am building minimum diameter for ultimate altitude, I go with lightweight performance, but all other builds default to cheap performance.

View attachment 521301

Yeah I'm well aware of the triangle... mountain bikes for example: strong light cheap... pick two. Some kits I've built were almost spot on... I was hoping...

 

[JackC]

Yeah I'm well aware of the triangle... mountain bikes for example: strong light cheap... pick two. Some kits I've built were almost spot on... I was hoping...

Curtis tends to be a bit generous regarding the weights he lists.

 

[DeltaVee]

Curtis tends to be a bit generous regarding the weights he

Likely many others do too I suppose

 

[DeltaVee]

@JackC, what do you use to "connect it all together" for your Arcas? I.e. I assume you use some kind of push pin/rivets to attach the av bay to the payload tube... and shear pins for the nose cone, how many and what size/kind? I use these small, expanding plastic push pins for a 3" diameter DD rocket (about 1/8" in dia) which do not appear to be adequate for the Arcas.

 

[JackC]

@JackC, what do you use to "connect it all together" for your Arcas? I.e. I assume you use some kind of push pin/rivets to attach the av bay to the payload tube... and shear pins for the nose cone, how many and what size/kind? I use these small, expanding plastic push pins for a 3" diameter DD rocket (about 1/8" in dia) which do not appear to be adequate for the Arcas.

The small push pins work fine. I use 4 of them to connect the drogue bay and main chute bay (4 on each side). Never had any problems with that.

If you think you need bigger ones, Giant Leap Rocketry has pins that are double the size. I use those on my 5.5” Nike Smoke. They are really strong and look great!

 

[Sandy H.]

I have gloves and a respirator and the statements I've seen regarding protecting ones' self isn't falling on deaf ears at least (I need to do a major cleanout of my work area in the garage...) so it's clear I can't mess with this material in the house!

Obviously this works if you have a bit of land out in the country, but not if you live in downtown New York City (NEW YORK CITY?!?!?! -bbq commercial, I think. . .) Anyway. . .

It isn't a bad plan to put a box fan or something similar upwind to ensure that any dust goes away from stuff (you, cars, house) if you're sanding (or painting etc.) outside. Its no substitute for keeping the itchy stuff off of you, but it helps move that away in case you either leave the mask or gloves off for a minute by accident etc. Probably obvious, but it helps.

Sandy.

 

[DeltaVee]

Obviously this works if you have a bit of land out in the country, but not if you live in downtown New York City (NEW YORK CITY?!?!?! -bbq commercial, I think. . .) Anyway. . .

It isn't a bad plan to put a box fan or something similar upwind to ensure that any dust goes away from stuff (you, cars, house) if you're sanding (or painting etc.) outside. Its no substitute for keeping the itchy stuff off of you, but it helps move that away in case you either leave the mask or gloves off for a minute by accident etc. Probably obvious, but it helps.

Sandy.

+1 on the box fan... very good idea! BTW: Pace Picante...

 

[JackC]

@JackC, what do you use to "connect it all together" for your Arcas? I.e. I assume you use some kind of push pin/rivets to attach the av bay to the payload tube... and shear pins for the nose cone, how many and what size/kind? I use these small, expanding plastic push pins for a 3" diameter DD rocket (about 1/8" in dia) which do not appear to be adequate for the Arcas.

I use 4-40 Nylon screws for shear pins. Two work just fine.

 

[DeltaVee]

I've been reading the info posted here over and over... skull is a bit thicker these days, I'm afraid, and things tend to take time to sink in! I want to say thanks to everyone for all the great advice! But I do have another question. The motor mount I chose is 75mm, so the centering ring width will accommodate a welded eyebolt that is only so wide... in particular, the washers are barely wider than the nuts... is this a concern for G10 rings?

 

[David Schwantz]

You can use a ply backer behind the G-10. Or fender washers, they are bigger in DIA. I have even ground them to fit around the MMT.

 

[DeltaVee]

You can use a ply backer behind the G-10. Or fender washers, they are bigger in DIA. I have even ground them to fit around the MMT.

The washers I've got that I'm thinking of using are literally .008" too wide... so a small grind I can do!

 

[mtnmanak]

I've been reading the info posted here over and over... skull is a bit thicker these days, I'm afraid, and things tend to take time to sink in! I want to say thanks to everyone for all the great advice! But I do have another question. The motor mount I chose is 75mm, so the centering ring width will accommodate a welded eyebolt that is only so wide... in particular, the washers are barely wider than the nuts... is this a concern for G10 rings?

You should be fine. Put your washers on and JB weld the snot out of the nut/washer on the underside of the CR. This is a relatively lightweight rocket at 20'ish pounds. And the booster will likely be about half that, so not a lot of stress on the forward CR during recovery.

Leave yourself a little room in front of the foreword CR and, after the whole motor mount is installed, pour a nice epoxy dam in front of the motor mount. Will help reinforce your CR and completely lock in your hardware.

 

[DeltaVee]

I'm also hoping Bob Smith 30 minute epoxy is up to the task of construction...

 

[DeltaVee]

I ended up getting west systems epoxy... I know folks rave about it here on TRF. One thing I wasn't quite prepared to deal with: The motor mount centering rings fit perfectly in the tubes of the airframes EXCEPT when it encounters the fin slots! I've been sanding the edge of one down for a while now and am making grudging progress. I guess once you slice up a tube it's not quite perfectly round any more... the rings slide nice and freely until you hit the slots. This will be a chore....

 

[mtnmanak]

I ended up getting west systems epoxy... I know folks rave about it here on TRF. One thing I wasn't quite prepared to deal with: The motor mount centering rings fit perfectly in the tubes of the airframes EXCEPT when it encounters the fin slots! I've been sanding the edge of one down for a while now and am making grudging progress. I guess once you slice up a tube it's not quite perfectly round any more... the rings slide nice and freely until you hit the slots. This will be a chore....

https://www.rocketryforum.com/threads/4-prometheus-mmt-issue.172955/post-2283379

 

[Steve Shannon]

I ended up getting west systems epoxy... I know folks rave about it here on TRF. One thing I wasn't quite prepared to deal with: The motor mount centering rings fit perfectly in the tubes of the airframes EXCEPT when it encounters the fin slots! I've been sanding the edge of one down for a while now and am making grudging progress. I guess once you slice up a tube it's not quite perfectly round any more... the rings slide nice and freely until you hit the slots. This will be a chore....

Once fin slots are cut into a body tube the material between the slots bends inward slightly. Centering rings can sometimes be forced through the constricted area, especially if they’re at a slight angle.
I epoxy the forward CR to the MMT and build up a nice fillet on the front side. Then I build up a bead of epoxy ahead of the fin slots.
I slide the MMT and forward CR into the BT at an angle. Then I use the MMT to straighten out the forward CR and bed it into the epoxy bead just at the forward end of the fin slots. I temporarily put in the aft CR to hold it in alignment while it cures.
Then I remove the aft CR, and epoxy the fins in place one at a time.
Finally I put another bed of epoxy even with the aft edge of the fin and along the trailing edge of the fin tab, then slide the aft CR in place so it’s tight against the fin tabs.
I measure all this out and mark it in advance so I end up with just enough MMT protruding through the aft CR to mount the retainer. It want the retainer body tight to the aft CR. The retainer, aft CR, MMT and fin tabs, and forward CR form a single fiberglass and epoxy structure with no air gaps where they all touch.

 

[DeltaVee]

How do you deal with a three CR mmt? I suppose I could use a rubber mallet!

 

[Steve Shannon]

How do you deal with a three CR mmt? I suppose I could use a rubber mallet!

Where does the third CR go? If it’s at the forward end of the MMT then just add it last from the front.
If it goes in the center of the fin tab do it the way I described above, epoxying it to the MMT, letting it cure, inserting it into the BT fin slots at an angle and then straightening it out. Any forward rings can be inserted from the front without passing through the constricted section. Any aft rings can be inserted from the rear, also without passing through the constricted section.
I’ve never needed a mallet. The MMT gives you enough leverage to get a ring started and then straighten it. I have put rings in nearly sideways (without the MMT) and then worked them straight. A piece of coupler helps a lot.