Two Stage Formula 54

[patelldp]

I was able to snag two Formula 54 kits from Rocketry Warehouse (great customer service, by the way!) and a Featherweight Altimeters Raven 2 + 38mm Av Bay (more great customer service!) from the Black Friday sales. Naturally, I planned to put them together into a single, two-stage rocket over the winter.

The goal of this project is to successfully complete and fly my first two stage rocket. I have never flown a high power rocket with more than a single motor in my 6 years of HPR certification and 10 years of total HPR flying. This should change that!

The rocket itself will be a VERY basic 2 stage model. The sustainer will be built stock for the most part. The major modifications will be to add a brass tube in the Centering Rings as a conduit for the ignition wires and to recess the aft centering ring 1.5" to allow for the interstage coupler to engage. The Raven will reside in the nosecone to handle apogee deployment as well as sustainer motor ignition, with some form of break away connection so that the ignitor wires break free at deployment.

For now, the interstage will simply be a filament wound 54mm coupler with a single bulkhead that will act as the booster's "nosecone." The booster will sport a 38mm motor mount instead of the stock 29mm to make room for some 38mm 2G and 3G EX booster motors. At a later date, I may add space for an Adept 22 in the interstage coupler so that I may fly booster motors without ejection charges.

The nice thing about this rocket is that it will also serve as two separate rockets, with two different sizes of motor mounts. If I want to fly them separately, I will have two unique boosters along with "smart" and "dumb" nosecones, meaning one with the Raven and the other without.

For starters, I have attached a picture of all of the parts after having been cleaned up with 220 grit sandpaper. I will be building this in the coming weeks. Tentatively, my goal is to have the sustainer ready to fly should I able to attend the MDRA December launch. The projected motor for the first flight will be an old DPS 24mm G112. I will be waiting until after Christmas to start the booster as I need access to some machines at my parent's place to make some parts.

[mainer]

I plan on doing a two stage also, but Im using a Wildman Jr booster to a Formula 54 sustainer with the Wildman JR ebay and payload section. I guess at that point its not a Formula 54 anymore, but its in there!

Keep us updated.

[McKailas Dad]

Very cool. I had never seen the tinted FG tubes till now.

Is that 'lemon' and 'tangerine', by chance?

Somebody should start a Formula 54 gallery. Mods?

I'd like to see some of the other colors.

I would have liked to pick one of these up at the sale, but all my money was previously allocated to another vendor

[patelldp]

Very cool. I had never seen the tinted FG tubes till now.

Is that 'lemon' and 'tangerine', by chance?

Yes, lemon and tangerine. i think the lemon is VERY cool, almost neon, while the tangerine is a little "bleh."

Somebody should start a Formula 54 gallery. Mods?
I'd like to see some of the other colors.

The gallery is here.

http://rocketryforum.com/showthread.php?p=242650

I agree that people should show the other colors. I'd be interested in seeing the other colors.

[maxvelocity]

I have a lime on the way

[dixontj93060]

Dan, do you have a Rocksim of the stack up? I am surprised that the sustainer can be built stock. I would have thought you would have to add length there to get the two stage configuration stable. /Tim

[patelldp]

Dan, do you have a Rocksim of the stack up? I am surprised that the sustainer can be built stock. I would have thought you would have to add length there to get the two stage configuration stable. /Tim

Tim -

I do have a Rocksim and will boot up my work computer later and post it. It is going to need a few ounces of nose weight to be stable on larger motors. IIRC, the CP is right around the fore end of the booster in 2-Stage config, and I will balance it when I complete the model.

I am considering building a 38mm tube into both cones for the Raven, but only weighting one for 2-stage flight.

[dixontj93060]

(Interstage coupler not shown right, but) Yep, I'm likin' it!

[patelldp]

Began construction tonight and got pretty far on the motor mount.

Step one was to mark the motor tube for centering ring and wire conduit locations. (Picture 1)

Step two was to gather all of the necessary components for the motor mount (Picture 2). That includes:

Motor Tube
2x Centering Rings
15' of 1/4" Kevlar
Plastic Drinking Straw (for the conduit)

First part of construction was to drill a hole in each centering ring to allow for the conduit to pass through (Picture 3).

Next, a hole was drilled for the Kevlar shock cord to pass through and be knotted on the end so that it would not pull through the ring (Picture 4).

[patelldp]

The first picture shows the adhesives used for this build:

US Composites Thin Epoxy
US Composites Phenolic Micro balloons as a filler
Super Glue from Harbor Freight (cheap and it works)

The next picture shows the motor mount tacked together with the super glue. This consists of placing the component where it belongs on the mount and adding a couple of drops of super glue to tack it into place.

Picture 3 shows the fore end of the motor tube with everything tacked into place.

Picture 4 shows the fore end of the motor tube with the addition of a fillet of epoxy mixed with the micro balloons. This mixture is very lightweight, but will also provide more than sufficient strength due to the size of the fillet.

[patelldp]

Last couple of pictures for tonight:

First picture shows the fillet on the aft centering ring. This picture shows the gap that exists from the end of the tube to the centering ring to allow for the interstage coupler. The motor tube will be flush with the rear of the body tube, allowing for 1.5" of engagement by the interstage coupler.

The second picture shows the rear of the rocket with the motor mount slid in for display. The fin tabs will be trimmed so that they will sit flush with the ID of the body tube. This will seal off the slots as well as provide some additional strength to the rear of the fins. They will not impede the sliding of the interstage coupler, which will be very loose to encourage drag separation of the stages.

[crossfire]

Looks like a fun build. Maybe notch the fin tab and use part of the fin tab to be glued to MMT. I can't wait to see it when you get it done and see how the flight goes.
GP

[alexzogh]

I hope you have room for a tracker in that nosecone!

have you simmed how high the sustainer will go? I'm guessing you are in for a long walk if you are just doing apogee deployment.

I made the horrible mistake of making my first two stage rocket too powerful. Never found he sustainer after the first launch.

I have a formula54 to littledog DD two stage rocket. No motor tube, or center rings in the forumla54 booster. Just surface mounted the fins.

The forumla54 kit really can't be beat for fiberglass parts. Even at it's retail price, it must be one of the best deals in rocketry. this will be a fun build to watch.

[patelldp]

I hope you have room for a tracker in that nosecone!

have you simmed how high the sustainer will go? I'm guessing you are in for a long walk if you are just doing apogee deployment.

Very good point! I have researched the Featherweight 38mm bay on this forum, and I believe that Adrian has said that the Big Red Bee will fit in-between the altimeter and its battery. Seeing as this will be my avionics package, I will definitely be including the tracker in there.

I am still waffling between upgrading the booster to 38mm or just leaving it as 29mm. There is always the "you can always adapt down, never up!" mentality, but in reality I have more options in 29mm. I have the following EX cases in 29 and 38:

29-1G
29-2G
29-3G
29-4G
29-6G

38-2G
38-4G
38-6G

Really, only the 38-2G would keep the booster close enough to the ground for a close recovery. I can't see myself ever putting a 4G or 6G motor in this booster, so I may go back on my original plan and use a 29mm booster.

A 29-6G I600 Blue that I have made in the past (have the static test video on my parent's computer, may load it to YouTube over X-Mas) should have plenty of punch for this thing.

[Bill P]

I am still waffling between upgrading the booster to 38mm or just leaving it as 29mm. There is always the "you can always adapt down, never up!" mentality, but in reality I have more options in 29mm. I have the following EX cases in 29 and 38:

29-1G
29-2G
29-3G
29-4G
29-6G

38-2G
38-4G
38-6G

Really, only the 38-2G would keep the booster close enough to the ground for a close recovery. I can't see myself ever putting a 4G or 6G motor in this booster, so I may go back on my original plan and use a 29mm booster.

You have more options with a 38mm motor mount. You have all the 29mm's in addition to the 38mm's or is it the 38mm's in addition to the 29mm's. Even if you never use the 38mm 4- and 6-grain cases.

[patelldp]

I have not forgotten about this thread, just haven't been working on these too much because I need to rethink a few of my design points...

The sustainer is complete for the most part. Only thing left to do is figure out an altimeter bay in the nosecone. It's much more cramped than anticipated, and I don't have the proper tubes on hand to get it done (38mm and coupler).

I have also found that the magnetic switch on the Raven 38mm Av-Bay may not be adequate for this application. The switch functionality is spotty at best when the unit is centered in a 54mm cone. The unit seems to turn on without any issue, however turning it off is unreliable. This becomes a problem should I ever need to power the unit down on the pad.

I plan to bring the cones home with me and work on them in my dad's shop. Hopefully after Christmas I will have two functional nosecones that accept the Raven bay, with one being weighted for the two stage configuration.

I'll post some pics tonight on where I stand currently.

[gdiscenza]

Dan,

I was following the original announcement thread for the 38mm AV-bay from Featherweight, and I seem to recall that Adrian was offering a more powerful magnet that could activate the switch from a greater distance. Maybe you could ask him about that?

Another possible solution would be to mount the AV-bay offset in the NC by 5mm or so, bringing it closer to the surface of the 54mm NC. Though if you have already set up the CRs, that might not be an optimal solution. With the minimal mass of the AV-bay, it shouldn't make a large difference in the trajectory of the rocket.

Of course, you're welcome to ignore me and scrap the Raven and use something else, in which case, you are welcome to appease my hurt feelings by shipping said Raven to me.....

G.D.

[patelldp]

I was following the original announcement thread for the 38mm AV-bay from Featherweight, and I seem to recall that Adrian was offering a more powerful magnet that could activate the switch from a greater distance. Maybe you could ask him about that?

Good idea, I'll have to look into that.

Another possible solution would be to mount the AV-bay offset in the NC by 5mm or so, bringing it closer to the surface of the 54mm NC. Though if you have already set up the CRs, that might not be an optimal solution. With the minimal mass of the AV-bay, it shouldn't make a large difference in the trajectory of the rocket.

This is what I was playing around with in my head. Basically an offset version of a standard altimeter bay set up. Install the 38mm tube against the inside of the cone, affix the Raven Av-Bay to the nosecone bulkhead, and then keep it in there via a T-Nut and eyebolt on the other side. I will show pictures of this at a later date.

Of course, you're welcome to ignore me and scrap the Raven and use something else, in which case, you are welcome to appease my hurt feelings by shipping said Raven to me.....

G.D.

Yea...

[patelldp]

So let's try to bring this thread back up to speed.

First picture is of the rail buttons installed. I marked the line with a piece of angle aluminum, measured approximately where I wanted the buttons, popped some holes, and onto the next step. Pretty simple.

Second picture shows the buttons nice and lined up. As you can see, the rear centering ring has been recessed 1.5" from the aft end of the tube to allow for the interstage coupler.

Third picture...Look at that! The fins are installed. I didn't take any pics of the installation or the filleting...sorry. This is a picture of the rear end with my 29-450 case installed. I then installed the rear snap ring, and dropped in a spacer. The spacer was made to make up the difference in length for my delay and non-delay 29mm bulkheads.

What this allowed me to do was the space out the bulkhead in the interstage coupler just enough to allow clearance for the central 1/4-20 all thread and nut, as well as for igniter wires to not get pinched.

Fourth, we have a picture of said bulkhead recessed inside the interstage coupler with a nice fillet. This will be filleted on the opposite side once cured.

[patelldp]

Last of the pictures for tonight.

First picture is a side shot of the bulkhead recessed in the interstage coupler. Right now this coupler is a snug fit in the sustainer, and a loose fit in the booster. This is backwards... I want the interstage to be a slip fit (drag separation is okay, if not preferred) while the coupler itself will act as a nosecone to the booster once the rocket stages. The coupler will hold an ADEPT22 unit in the cavity above the bulkhead in the picture (which is really below the bulkhead when the rocket is ready for flight.)

The second picture shows the rocket stacked next to our pitiful Christmas tree. Our two brother kittens enjoyed climbing in it, so now it's locked away in our spare bedroom where I do my rocket building. The rocket has an interesting profile for a 2 stager...typically the upper stage is significantly longer than the booster. I will see what stability looks like, but at least for the time being I will fly it as you see it to low (< 5,000') altitudes.

Last pic is of everything that will be in the rocket for recovery. The booster has 15' of 1/8" TK from 3 Dogs Rocketry and a 24" Top Flight parachute. As mentioned before, the Kevlar will be attached to a bulkhead on the bottom of the interstage coupler, which will act as a bulkhead once the rocket separates. The sustainer has 15' of 1/4" TK from Rocketry Warehouse and has several options for recovery: the 18" Mil-Spec chute you see, a 14" Loc chute, or a Top Flight streamer. I have no doubts that this will recover fine with the streamer if I choose to put it up to a mile. My only concern will be bouncing the nosecone which will be housing the Raven and 38mm Av-Bay. Lastly, we have the two Von Karman nosecones. I haven't decided if I will be building Av-Bay's into both, or if I will just cap one off for when I fly one or the other on EX motors with delays. Or maybe one will become the cone for my 54mm Crank...

I will be doing more with this in the coming days. I plan to fillet the fins on the booster, close off the fin can with the rear centering ring once I install the t-nut, and then cut the necessary parts for the interstage e-bay and nosecone e-bay's over Christmas. I will be sure to snap some pics.

Merry Christmas!

[patelldp]

I have finally been able to make the necessary parts for the 2-Stage Formula 54's nosecone. All it took was access to a decent wood working shop and I am on my way.

I had a few design CTQ's for this cone:

1. A sealed bay for the Raven and its 38mm Av Bay
2. Must include an eyebolt for recovery attachment (no Kevlar/knot/epoxy)
3. Positive retention of the Raven and Av Bay

The resulting design is the following:



Another angle of the Raven:



The Raven going into the cone:



And lastly how it is retained:

[patelldp]

Some specs on the bay:

The tube is 2.5" of LOC 38mm motor mount. Plenty strong and nice and lightweight, as is the 38mm coupler being used with the 38mm Av-Bay. The 38mm tube is epoxied to two 1/8" thick rings with offset holes, and then finally epoxied into the cone. The bottom ring has a heavily ground 10-32 t-nut that was reinforced with as much epoxy as possible on the backside so it will never come out.

The eyebolt is your standard 10-32 eyebolt with a single nut. I plan to add a split washer so the eyebolt doesn't unscrew itself. The retaining bulkhead was supplied with the kit, and it's 1/16" thick G10. The four 4-40 all-thread locations were transferred from my Raven's active bulkhead to the G10 bulkhead and holes were drilled.

The resulting cone is only slightly heavier than the stock cone, even with the Raven in there. I'm not concerned about using a non-welded or forged eyebolt in this application, as the cone will be on the end of 15' of 1/4" Kevlar and the chute/streamer will be attached to that cord. The eyebolt only has to withstand the loading from the cone, and that will be very little due to its low weight.

Now that this has been accomplished, I really have very little to do to finish this project. The booster needs final filleting, the interstage coupler needs a bulkhead (will make that and document here), and I need to order up an ADEPT22 for the interstage.

First flight will be in January at MDRA. Planned flight is an Aerotech H128W to an EX 29-2G Yellow.

[grouch]

Nice work on the av bay!