Setting a new standard in rocketry
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Setting a new standard in rocketry |
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Sponsors: Cesaroni Technologies My second N1 was a 3 stage rocket flying on 42 motors. We used 24 D11s and 6 G80s in the first stage, 8 G40s in the second stage, and 4 F25s in the third. It flew well, but the third stage went unstable. We did not get chutes deployed on the first or second stage, and unfortunately the rocket was lost. The idea for this rocket came from the success of our club project of the 1/7 scale Vostok, first flown at Plaster Blaster 3 in October, 2004. Each year we do a a big project for Plaster Blaster, so after the Vostok flight there was a discussion about the next year's project. Several people wanted to do an American rocket, I have a love for the Soviet designs. So, we decided to make one of each, a 1/16 scale Saturn V and a 1/16 scale N1. The Saturn V team is being headed up by Ken Sparks of Phoenix, AZ. A note of thanks to
Anthony Cesaroni and the entire Cesaroni team for their fantastic support on
this project. With their ease of loading, super reliable ignition system, and
low cost of hardware, the Pro38 motor family was the best choice to power our
N1.
Construction:
The outer skirt framing is
being glued into place. This was a tedious task. The blocks are there to hold
the ribs in position as the epoxy sets. I did 6 ribs at a time with 5 minute
epoxy.
This operation took the
majority of the afternoon. It was glue and wait, glue and wait.
After mounting all the 38mm motor tubes, the top ring is glued into place, making an amazingly strong structure that only weighs 15 pounds.
Here is the view from the
bottom of the first stage. Still a long way to go, but making progress....
Mike B. cuts the foam into
strips, then into blocks that will be shaped to fill in the space between the
ribs. There are 24 foam blocks cut into wedges to fit between the plywood ribs.
The foam is held in with epoxy. It is not as tedious a job as you would think,
it took us a coupl
Here Bob H. and Phil V. start cutting and inserting foam into the lower section of stage 1.
We installed the foam into alternating locations to prevent the ribs from being pushed in the same direction. Here Bob H. is painting the epoxy and is about to insert a block between the two.
Phil V. and Andy W. finish off fitting the foam blocks into place. Once all the blocks are epoxied into place the lower section became very rigid. The entire assembly at this point weighed 15 pounds.
Mike B. adjusts the voltage on
the variac and Andy W. trims the foam with the bow. Bob H. rotates the assembly.
We used a 1" pipe through the central tube which will become the launch rod
guide to spin the assembly on. It worked perfectly using the upper and lower
rings as a guide for the hot wire.
Another shot of the trimming.
Note the area below the bow and how clean the cut is.
Andy W. and Mike B. cut another of the giant centering rings. This one is for the first stage, about 1' up from the bottom where the rocket has one of it's many shape changes. The Soviets used almost no straight tubes on this rocket. It makes it particularly difficult to model accurately. While we are not scale freaks, we did want to make it as accurate as possible.
Bob H. peeks through the mid centering ring of the first stage. The 10" diameter hole is for the internal structure of the rocket. We will be using a central tube for strength with the foam, ply, and glass outer skin. This will yield a light and very strong airframe (we hope....)
Here Andy W. prepares the
central tube of the first stage. The tube mounted sideways into the main 10"
support tube is for the dual side ejection of the recovery system of the first
stage. This tube will house two 15' cargo chutes, one ejecting out each side of
the rocket.
A shot of the same section of the first stage from below the ring. This odd ejection system is the easiest way to do recovery as there is an elaborate aluminum interstege coupler that sits on top if the first stage, making standard top ejection impractical.
The 54mm motor tubes (we will be flying it on 38mm motors first flight) are finally glued into place. We used a 10" centering ring to hold the main support tube centered on the launch guidance tube. This tube will later be extended to be 55" long to make it easier to get a launch rod onto the rocket.
We added ribs to the central tube for strength. The booster takes a lot of stress being moved around and in flight. We wanted a super-rigid structure, that was also very light.
Here Bob and Phil stare gluing
in the ribs for the second section of the first stage. This section will be
difficult to trim the foam as we cant get the bow in easily. We will figure that
one out when we get there.
After all the ribs are in place, we decided to glass the lower section to prevent the foam from getting damaged when working on the next section up. We used epoxy and 7oz satin weave cloth. We will add another layer of cloth to the lower section once all the foam on stage 1 is in place.
The foaming of the middle
section begins. This is where we all decided to call it a day and have a beer.
We made great progress after just three build sessions.
Build session number 4. Phil
starts off the day with his favorite pass time, fitting foam wedges into
unusually shaped spaces.
Bob H. trims one of the 24 foam blocks that comprise the second transition on the booster. There are a total of 72 foam wedges on the first stage alone.
Phil V., Bob H., and Dave M.
epoxy in all the wedges for the second section of the first stage. These have to
be done as a set otherwise the ribs will bow.
Here the group is gluing in the long stringers that will complete the first stage structure. These are tricky due to the length. The position of the stringers was marked on both the lower and upper rings to make sure they were all spaced evenly and were perpendicular. We used CA to hold these in place because of the angle, epoxy would have taken forever. The joints will be reinforced when the foam is epoxied into place.
Throughout this process of gluing, holding, aligning, breaking out what the last guy just did, and the occasional beer, the question "What were we thinking?" kept coming up. A project of this magnitude and complexity requires a fantastic group of builders and a certain amount of insanity. Fortunately, I have the privilege of being associated with the first and am overqualified on the second. Just wanted to say thanks again to all our builders and especially to the Cesaroni corporation for their fantastic support on this project!
Finally all the stringers are
in place and the foam has been trimmed for the middle section. When we were
putting in the stringers, we used several cans of paint and other heavy objects
to hold the plywood ring in place as the epoxy holding the middle sections of
foam cured. To save time we were installing the upper stringers while the epoxy
was curing. We did manage to remember to take all the cans out prior to gluing
in the last of the stringers, although it was close......
Mike B. drills the motor tube holes in the lower section of the second stage. This is the smallest stage of the rocket, is not have as oddly shaped as the first stage. We should have it knocked out quickly. The interstage couplers will take a bit more time, they will be made out of aluminum rods and rings bent and welded into shape.
Mike B. and Phil V. route out the lower ring for the second stage. We are using 10" diameter tubes for staging couplers and will blow the stages apart prior to igniting the upper stage. I have used this explosive staging on all my multi stage rockets, it works well and prevents the lower stage from getting cooked by the motors in the stage above it. We plan on flying this beast more than once, providing the California lottery cooperates and I can afford motors for the second flight....... After these rings the temperature made working a little too unpleasant, so we packed it in for the day. Lots of progress and nobody died. Thanks to Phil V., Bob H., Mike B., and Dave M. for all their help! As we wrapped up this build session we enjoyed pizza and talked about next year's project. I mentioned a 1/2 scale V2 and everything went dark. All I remember waking up with a throbbing headache..... Many moons later...
Here Bob M. and Robert H. are cutting one of the 24 wedges of foam that will be used in the upper section of the first stage. We decided to use a template to guide the hot wire to make the wedges. This worked very well as it made all the wedges the same and much easier to fit.
We ran clear tubes from the recovery mortar tubes to where the electronics hatch will be. These tubes will guide the leads of the E-matches used to blow the chutes on the first stage.
Gluing in the foam on the upper section of the first stage was a piece of cake, thanks to cutting the wedges with a template and making them all identical. We had to fit a few scraps around the ejection mortar tubes, but that took just a few minutes.
Here is when we left one of our cameras inside the first stage and we shook it really hard to get this picture. Not quite. Before gluing in
the last form piece, we snapped a shot of the back of the electronics bay and
the tubes that guide the wires to the ejection mortars.
Here is a shot of the electronics bay. The two holes are the ends of the tubes. This completed the structure of the first stage. Below is a shot of one of the mortar tubes. These tubes will have wood caps and a piston inside to push the chute out. There will be two 10' chutes for the first stage. It should weigh in at about 60 pounds with the expended casings.
Here we used a bench vice and a pole to make a "Barney Rubble" lathe for trimming the foam with a hot wire. This worked very well, and we wasted a minimum of foam. After the cut there is almost no finishing, just wipe it down and move on.
Here I am trimming the foam wit the hot wire. Phil was taking the pieces out as they were cut, while Bob rotated the tube. Other than breaking the wire a few times, this worked surprisingly well. The finished cut was very smooth.
Here is a good shot of the the finished cut next to the uncut section. Cutting the entire rocket took us about 10 minutes. Below is Robert Hafner cutting the 10" tube that will be used to make the staging mortar for the second stage. This tube will also keep the stages together, we hope.
Here we are preparing the upper section of the first stage for glass. We used 7oz satin weave cloth and epoxy to glass the stages. Cant use polyester with white foam, it has the same effect as salt on a slug.
We are assembling the structure of the second stage. With the smaller diameter we decided to forgo the plywood ribs in favor of additional glass on the outside. The lower ring has the ignition wires on it for lighting the second stage motors. They will be lit after the first stage is separated and clear from the second stage. Again, this is all theory. Yeah, That's it, theory.
The Interstage assemblies had me worried from day one. In the last N1 I build I used aluminum rods and rings, and JB Weld to hold them together. When it crashed (chute didnt deploy), both interstage assemblies came apart in 192 little pieces of aluminium. This would be bad in a 300 pound rocket, and the interstage assemblies are structural, they see the weight of the rocket. First problem was how to make an upper and lower ring for both interstage assemblies. After a few ideas were dismissed, Bob Mosley from Aeropack suggested waterjet cutting rings from 1/4" aluminum plate. Mike Jerauld drew up the rings, with slots for the vertical rods and holes to mount them to the stages, and Bob had them cut. They came out beautiful.
That night Mike Brock and I cut the aluminum rods and played with fitting them together. Everything went together so well, we decided to build the final assemblies. I broke out the argon wire-feed welder and played with welding in the rods. It worked like a champ, so we spent a couple of evenings assembling the Interstage assemblies. It was a little nerve racking welding on these very expensive rings, but all came out well, and the rings are amazingly strong.
Here is a shot of the first two stages in place. It is starting to look more like a rocket.
The yellow on the second stage is foam used to fill low spots. The hot wiring of the second stage had some problems. Anything can be fixed with a little filler.... I will be working on the beast in the evenings, the next big build session will be in a week. Time is getting short, but with the Interstage assemblies done, things will move along much faster. The third stage lower end is cut and can be glued together. We will have pop-out drag fins on the third stage for stability. Those will be fun to engineer.... Sunday, 9/3/2005. Mike Brock and I came back from the TRASD launch early and put a little time on the beast. We wanted to get the transitions finished, they need their center ring. That took a lot of bending and a few burnt fingers (it helps to remember where we just welded), but we got them done. This is trimming the middle ring. Once it was cut we welded it together. This made the rings even stiffer. Those Russians knew how to build transitions, now if we could just teach them to make tubular rockets rather than all these conical shapes.........
The next task was to make the
two exposed fuel tanks. These reside inside the transitions, and are half
spheres. Mike Brock found some large round balloons on the web and ordered them.
We inflated one in the transition, using the aluminum ring as a guide, then
glassed right onto the balloon. We had fears that the resin would attack the
balloon, making it pop and leaving us looking like the agents in the beginning
of the movie MIB, you know, slimy things dripping from out hats....... Turns out the resin and the balloons got along well, and the fuel tanks were a piece of cake.
We used 7.2oz satin weave cloth and polyester resin. The cloth took to the balloon well, just had to make a few cuts to accommodate the shape.
The larger dome was a little
harder, but still only took 15 minutes or so. We were both pleased with how they
turned out. Minimal sanding and they will be perfect. The third stage is proving to be the most complex. With no fins and a very small flair, from my experience, it is not stable. Rather than having it tumble, we decided to go with pop-out fins. This took a little engineering.
Here is a look at the inside of the bottom of the third stage. The motor tube is in the center, and the bungee cords are the springs that pull the fins out. The fins are released when the coupler that joins the second and third stage leaves with the staging charge. That is why the fins have a slot in them. It hooks the coupler. I know the fins are an odd shape, but this thing will be going very slow. Flutter is not a real concern.
More detail of the fin in the deployed position. We tested them about a hundred times at several attitudes before we sealed them up. They should work. I think. I hope.....
Moving right along, I glued the foam ribs into place in the lower section of the third stage and here I am hot-wiring the shape. Other than breaking the wire a few times, this went very smoothly. It yields a surface that is ready to glass, no sanding.
Adding the foam to this section went very quickly. I cut the wedges on the table saw and seated them with 3M 90 spray adhesive. You have to let it dry otherwise it melts the foam. That is messy. Very messy. Kind of like salt on a slug.
The project is seeming like it will actually come to an end soon, just three feet of rocket to go!
The body fairings had me worried from the start. Glassing foam would have made for a lumpy set of fairings at best, and would have been no fun to sand. After much pondering, I opted to make a mold for all fairings, and make them out of fiberglass, filled with expanding foam. These are the plugs for all the fairings. They go over one of the 300 bends this rocket has, that is why the plugs are bent.
Here we are sanding the mold getting it ready to try out. You are supposed to wait 24 hours before using a mold, we were short on time, so we opted for the 24 minute timeframe. We paid the price, the first pieces stuck a bit. Spent an hour cleaning the mold. Ok, maybe I am not so trainable.
Even after being stuck, they came out in good shape. It will take a while to make them all, but they will be very strong and light. One more task down.
Glassing the third stage. I used one piece of glass to add strength. I look a little annoyed in this shot because I just poured half a cup of epoxy on my shoes. That stuff is sticky.
A few small things remain, but we will be painting it in a couple of days. After paint we put on our great sponsor's logo (Cesaroni Technologies and PerfectFlite), and do a dry-run on getting it on the pad.
After a few coats of paint, we added some scale detail. Here is one of the "Drag Plates", or fins for the first stage. It is made out of welded aluminum (I love my new MIG welder). The center is supposed to be a grid, but the scale holes were .25mm, so we opted for solid plates. We also decided to make a
carrier / erector for the rocket. A beast this size is too hard to move around
and transport. The trailer we built solves this problem, also makes it a lot
easier to stand the rocket up. Remember, there is 100 pounds of ballast in the
nose cone. That tends to make things a little hard to stand up.
The carrier for the rocket is lifted to about a 20 degree angle, then the yellow ropes are used to pull the rocker erect. Once standing up on the pad, the straps are removed. The carrier has a ladder built into it, which we use for arming the PerfectFlite electronics.
The person in the green shirt is ballast to keep the nose of the carrier from flipping up as the rocket stands.
We do not use redundant electronics as I have a lot of faith in the PerfectFlite electronics. They work, every time. We test many times in preparation, and we strive to keep the systems simple. PerfectFlite electronics have proven themselves over and over again. The motors for the project are
all Cesaroni Pro38s. We are using a variety of two through six grain standard
propellant motors. A special thanks again to Anthony Cesaroni of Cesaroni Technologies for their fantastic support on this project. Also thanks to Peter Lawall and PerfectFlite for their support with the electronics. They make electronics easy! I wanted to thank all the team members for their work and great support of this project. Mike Brock who spent countless hours with me on every aspect of the project. Phil Vanderschlaegen who drives 45 minutes each way a few times each week to work on it. Robert Hafner for all his time and great ideas in the project. Thanks to many others that have contributed their time and resources to helping out including Bob Mosley of Aeropack, David Marshall, Mike Jerauld, Alex Reid, Chris Williams, Ken Lehman, and many others. All that is left is to push the button!
Plaster Blaster 4 - The Launch I will post more pictures of the preparing and launching of the rocket as I get them. Here is what happened..... The rocket made it to Plaster
Blaster without incident. My trailer was a "little" heavy with this and
everything else in it, bit slow driving and lots of sweat got us there. To clear
up some confusion on the trailer the rocket is sitting on, that goes inside my
45' store trailer. We did not drive it down the freeway on it's carrier. Here is a shot of the aft end
the next morning. We towed the rocket out to the launch pad with a small quad. Much nicer than humping it out by hand. Setting it up did not go as smoothly as planned. We had a rod length problem, it was too long.
The carrier doubled as a ladder to access the top of the rocket to arm electronics and charges once it was standing. My son, Alex, is on the ladder receiving direction for the on-board video camera.
Once the supports were in place, the rocket was very stable on the pad. A few trips up the ladder to arm things and we are ready to go. The first stage has a single PrefectFlite timer for ejection of the chutes. The second stage has two PerfectFlite timers, one for staging and one for the chutes, the third has two PrefectFlite timers, one for staging and one for chutes, and the escape tower has one PerfectFlite timer with a G switch for the charge and ignition of the D12 in the tower. All the timers except the tower use pull-pins. I was afraid that there would not be enough acceleration to trigger the timers. We tried one with a G switch in the tower on Peter Lawall's recommendation. Of course it worked perfectly. They dont call them "PrefectFlite" for nothing!
The Cesaroni Pro-X motors use an electric match to ignite an ignition pellet in the top of the motor. This system allows for a low current ignition of any motor, and a super-reliable pressurization of the motors. For clustering, I have used Cesaroni Pro-X motors for all my giant projects. We have always has them light, every one. They are perfect for multi-stage rockets as you can fire lots of them from a standard 9V battery (I have done up to 12 with a single PerfectFlite timer and a 9V battery). For clustering the Pro-X motors have the perfect flame. You can almost count the motors in the picture!
Here is a super shot of the second stage igniting and the first stage separation. Out mortar cannon staging system worked perfectly. The second stage motors were lit from a batter onboard the second stage through a micro switch on the coupler. Once the first stage was gone, the second stage lit. The rocket leaned into the light wind a bit, but it was a very cool liftoff. The first stage chutes fired, but the chutes took a little too ling to open, the first stage landed hard. The second stage chutes were
perfect.
The third stage worked perfectly also. Here is a shot of the beginning of the third stage separation. The pop-out fins are just coming out and you can see the separation of the second and third stages. We staged them .5 seconds after motor burn-out. You can see the "puff" of smoke just below the rocket. That is motor burn-out. The Cesaroni motors perform we well and are so predictable that it makes projects like this almost easy. Also the PerfectFlite minitimers have a .1 second resolution, also making timing a dream.
This project was a lot of fun, and the result was extremely satisfying. Having a team as fantastic to work with as I have been lucky enough to enjoy, then the project working so well, is what this hobby is about. One final thanks to our great sponsors, Cesaroni Technologies and PerfectFlite. Without them, this would never have gotten off the ground! Next year, Space Ship one and the White Knight. The White Knight will be turbine powered with a 20' wingspan, and the Space Ship one will use a Cesaroni M motor. Stay tuned for that project!.
Andy Woerner |
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Copyright © 2003 Polecat Aerospace
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1/16 Scale Soviet N1
the position of the motors and ribs. I was going to use all 54mm motors in the
booster, but to save the weight of the reducers (and I didn't want to make 30
54-38 reducers), I opted for 38mm outer motors leaving the center ones 54mm.
Handling the 42" disk on my drill press proved to be a wrestling match. I
eventually won, but the ring and I exchanged punches a few times.
After completing the
outer skirt supports, I started on the central supports. I chose to work from
the outside in as the outside needed to be exact, I could fudge on the inside.
The idea of the inner ribs was to have the motor tubes rest between the ribs,
becoming a structural part of the airframe. This seemed like a good idea, but it
required a lot of precise machining of the ribs.
e
of hours to get them all fitted and glued into place.
Here
is a close-up if a foam wedge being fitted. The edge is beveled on a band saw,
then the piece is fitted into place. There is a lot of excess left outside
intentionally. This will be cut off later using a hot wore bow. The wood ribs
are intentionally recessed to stay out of the way of the bow when the foam is
trimmed.
Here
is a shot of the upper ring of the first stage. The 10" support tube has a
centering ring inside it to support the ring and to secure the launch guidance
tube into. The horizontal tube is the recovery system. The horizontal tube will
be trimmed after the frame and foam is in place and glassed.
ow
Here
we are moving onto the second stage. There are 8 38mm motors in this stage (much
easier than the 30 in the first stage!). We are using a 10" tube and coupler as
a mortar to separate the stages. Phil and Robert are cutting the hole for the
mortar tube in one of the second stage rings. Robert is very trusting of Phil
and his jig saw.
The
second stage internal structure is complete. We put the foam in using wedges
notched for the motor tube assembly. I dont thing anyone had a camera that day.
This
is looking into the top of the fin can for the third stage. You can see the fins
in their resting position, and the coupler that holds them in place. The coupler
is attached to the second stage (not in this picture). and the staging charge
goes in this chamber. Later a bulkhead will be installed sealing this chamber.
Here is more detail of the fin
in the retracted position. There are bungee cords on both sides of each fin.
That is in case one breaks. There is no way into this thing once the body tube
is put in place.
Here you see the fins in their deployed configuration. The bungee cords have
almost no strain on them. This is how we store the rocket to keep the bungee
cords fresh.
Well,
too late now, the fin can is glued into the body tube. We had to beat it in with
a sledge hammer. Once in place I used a brad gun to hold the tube in position
while the epoxy cured.
Here
is the upper section of the third stage. The upper ring is where the rocket
changes shape (like it seems to do every few inches, those crazy Russians). This
tube is very thick as it will house all the weight required to balance this
thing. My guess is about 100 pounds of weight will be needed. Swing testing it
will be fun, I wonder if King Kong is available.......
The
upper section of the third stage also went quickly. Sorry no pictured of cutting
the sections here, I was by myself and ran out of hands.
Sorry,
not a lot of pictures of making the mold. It is a sticky process and I did not
want my camera glued to the bench. I did that to a cordless phone once, had to
answer it with my head on the bench. I learned my lesson.
We
decided the domes inside the interstage couplers were a little too thin, and
rather than add more fiberglass we tried painting the inside with pout foam, it
worked perfectly. The foam stiffened up the domes and only added a few ounces.
Plus it was lots of fun to play with the foam as it was bubbling up.
Here
is the capsule. It is turned out of Bass wood. We made it heavy and strong as it
will see the ground first. It gets glued into the tube and the balancing weight
goes tight behind it. The escape tower assembly plugs into the top of the
capsule. I have not engineered that at this point. We have decided to eject the
escape tower rather than letting the rocket land on it. That should be fun to
figure out.
Here
is the entire third stage assembled. The escape tower is a pile of PML tubes and
boat tails, along wit ha little pour foam. It is a rocket in itself. We will use
a D12-3 to push it away from the capsule and the ejection will pop a chute out
of the nose of the escape tower.
A shot of all the volunteers pulling the rocket vertical. It was very easy and
all the equipment worked perfectly. You can see the giant launch pad we made
under the rocket. It has a footprint of just over 18' across. The launch rod is
a 1" solid steel rod. It is in the center of the rocket and extends up to the
top of the second stage.
We
had to get some help from our friends from Arizona with a few pieces of their
scaffolding to support the rocket after it was erected. There were a few tense
moments as the second stage was balancing on top of the rod and the entire
rocket was wiggling. 
Here
we are about ready to go, just adjusting the launch angle. The pas the rocket is
sitting on has legs that extend out 12 feet from center. We welded up the legs
to extend the existing legs on one of out club's giant pads. It resembles a
super-sized Estes pad.
We
had a raffle to see who got to push the button on the rocket. We had two mis-fires
(that helped the nerves). The raffle winner gave the controller over to his 10
year old nephew who had the touch. All 30 motors in the first stage lit exactly
at the same time. The rocket lifted off in a thundering roar and accelerated
surprisingly fast.
Here is a
small far-away shot of the second stage under it's two chutes. The second stage
came back without damage.
Here
is ejection of the third stage. Note that the escape tower is gone. We fired it
right at burn-out of the third stage. The chute used here is a 32' man rated
chute. The top of the nose cone is the heaviest piece. weighing in at just over
120 pounds. There are 20 five pound weights in the tip of the nose. The CG was
perfect, all three stages were stable and flew very well.
The
third stage under full chute. Note the full deployment of the pop-out fins.