Sprite - 6" and a baby O

Hello everyone,

This is a project I've been working on for about a year, counting design time. If I can get it finished in time, it should launch at LDRS. Work may not allow me to get it finished, unfortunately.

The rocket is designed around an EX motor - a full N or baby O, depending on how and with what it is loaded. The intended propellant for LDRS is Orange Sunrise. Smaller motors can be used of course, with an adaptor cage.

This rocket is deliberately overbuilt, to help keep the altitude down.

I'm including the rocksim file, but don't consider it 100% accurate. It is close. I also used RasAero in the design process.

Special thanks to Jerry O'Sullivan (experience and build assistance), Alan Anderson (shop space, encouragement, and spare hands), Ben Russell (fuel characterization), and Ed Romani (motor hardware).

Current status:

No paint yet. Nosecone completed. Motor hardware in hand. Fuel development is as completed as it's going to get before LDRS. It should work fine. Ring cage completed. Lower tube slotted and angle blocks are attached. Fins are shaped, fitted, but not glassed. I'm in the process of making the 6061 aluminum fin support angle strips. Electronics bay needs allthread and contents.

Electronics will consist of Telemetrum, Marsa54, GoPro Hero2 (pointed at horizon), and if I have time, a ContourROAM pointed downwards. CO2 and tether deployment will be used.

I added a picture of a test burn of an Orange Sunrise L from this past weekend at MDRA. I wanted an intermediate sized motor test instead of scaling straight from 38mm. The 114mm motor grain configuration is a tablet smoke + fuel, and 5 Bates grains. The last two have increasing core sizes and decreasing lengths. Liner and casting tubes are phenolic, and will be bonded together with Gorilla Glue.

About the fuel - it is close to a plateau burn. It was developed to be quite insensitive to Kn over a very wide range. The hardware will be running a high Kn. More details can be found in the Research forum under the Sandy Propellant thread. I'll answer questions about the fuel there, for those who are interested.

It is likely that I won't have much time to post on this thread or to provide pictures. But I thought I'd let everyone know about this project in case there is any interest.

Gerald







View attachment sprite v4.rkt

I thought when you titled the thread Sprite, you meant an upscale Estes Sprite like this one 16" body, 48" ring diameters. Flown on 25,000 N-s motor to about 4000 feet.

No... This one is a 6" rocket with disassemblable fin and ring cages. It can be stipped down for parts replacement if that is ever necessary. Right now I'm thinking that triples the work involved in construction, but it makes for a cool rocket. I'll do it this way - once!

The screencaptures from Rocksim indicate that no motor is loaded but that is incorrect. The motor is included, via motor tube, bulkhead, nozzle, fuel mass..., as part of the Rocksim file. It is just not "loaded" from Rocksim's perspective.

The motor tube is used as a structural reinforcement member, via the rings. It extends into the bottom of the coupler where it engages the last centering ring. The coupler itself is double walled - triple at the switch and video band. It is extremely beefy.

The bottom bulkhead of the electronics bay bolts to the top of the ring cage allthread. This allthread extends to the bottom of the rocket where it is attached to the thrust ring. The retention ring bolts directly to the thrust ring. The fins, the lower rings, the support spars, and the aluminum angle pieces all bolt together which should make the assembly quite rigid. So I do not expect to drop the heavy motor case regardless of what happens during deployment. Four pieces of overkill allthread will transfer the loads to the top bulkhead of the electronics bay. The electronics bay is also bolted to the upper tube through the wall.

The fins are S-glass over 3/8" plywood for this round. I had intended honeycomb core fins but there is no time to make them. I may make some stiffer fins to swap in, if the opportunity ever arises to really make this thing howl.

Recovery is via 4' Rocketman drogue, and a Rocket Rage toroidal main. The drogue nests in the base of the nosecone. The main sits in its bag just below this. I have drogues of different sizes available. I may make the choice of which one to use at the launch, based on wind conditions. The larger drogue I can get away with, the more cool video I'll get!

There is a nosecone electronics bay with sled. I had intended to put at least a beeper in there but it won't happen this time around.

The rocket is expected to break mach with a healthy margin at LDRS (est 1.4 or so). It should be capable of making nearly mach 2 with the right propellant, geometry, and nozzle. But the first flight on the motor will be a relatively mild one. The propellant is designed to be mild. The nozzle is also underexpanded which will help keep the performance down though it should make quite cool mach diamonds! Data from the first flight will let me know how much harder I can push it in the East.

The rocket was designed with some consideration of giving it a booster at some point. Whether that ever happens remains to be seen. Too many projects and not enough time!

Gerald

G_T said:

I added a picture of a test burn of an Orange Sunrise L from this past weekend at MDRA. I wanted an intermediate sized motor test instead of scaling straight from 38mm. The 114mm motor grain configuration is a tablet smoke + fuel, and 5 Bates grains. The last two have increasing core sizes and decreasing lengths. Liner and casting tubes are phenolic, and will be bonded together with Gorilla Glue.

Click to expand...

Was the L a subscale of the 114mm grain configuration? What was the motivation to put short grains near the nozzle despite the issues with a configuration like that?

The L was a pretty fair approximation for the 114mm. It should have been essentially a full L. The burn was super smooth just like the smaller motor tests. I'm more comfortable scaling from that to the baby O than from the smaller motor tests.

The reason for the grain dimensions is volume loading while avoiding erosive burning anywhere in the core. The percentage of core which has reduced web is decreased. Yep, the bottom grain will burn out first. But the grains are bonded, the wall is essentially doubled phenolic, the fuel operates well over a very wide Kn range (and is starting at the higher end so as Kn drops it still performs fine), and will be running at a bit lower temperature than most AP formulations (it was designed to do so). In other words, I can get away with it just fine. The volume loading allows me to get into the bottom of the O range using a readily available and somewhat economical 36" phenolic liner. One lesson I've learned through developing this motor is to start the process by identifying the liner.

Assuming success with this motor, I'll be scaling it up in size and L/D for a minimum diameter project. At that point, the core stepping will likely be double tapered to achieve more uniform burnout and to deliberately use erosive burning while leaving more resident time for the stripped propellant to burn inside the motor rather than somewhat outside. In other words, the grain geometry will become more complex. I'll be pushing that motor much harder as performance (altitude) will be the goal.

The motor for Sprite is essentially the smallest friendly O I came up with. I wanted my first medium sized motor to use a longer burn propellant formulation and a high Kn, but also wanted to keep the probability of success very high. So the resulting motor is perhaps slightly different than the norm in some details.

Better that further questions on the motor be placed in the EX forum. I hope I haven't gone too far in the discussion already.

Gerald

That's a pretty awesome flame color.

I dunno if discussing this would need to be in the research section or not, but I have a quick question: would adding table salt (sodium chloride) to propellant create a really bright yellow flame from the sodium?

G_T said:

The reason for the grain dimensions is volume loading while avoiding erosive burning anywhere in the core. The percentage of core which has reduced web is decreased. Yep, the bottom grain will burn out first. But the grains are bonded, the wall is essentially doubled phenolic, the fuel operates well over a very wide Kn range (and is starting at the higher end so as Kn drops it still performs fine), and will be running at a bit lower temperature than most AP formulations (it was designed to do so). In other words, I can get away with it just fine. The volume loading allows me to get into the bottom of the O range using a readily available and somewhat economical 36" phenolic liner. One lesson I've learned through developing this motor is to start the process by identifying the liner.

Click to expand...

I guess I should specify: I was referring to combustion issues up to and including spitting a short grain out the nozzle not the thermal issues associated with staggered grain burns.

G_T said:

The motor for Sprite is essentially the smallest friendly O I came up with. I wanted my first medium sized motor...

Click to expand...

You must have big plans. Do you mind sharing the specific impulse of the propellant in this motor? The impulse you are delivering is ... high.

It is not so much a specific impulse thing as a volume loading thing. That is at 93%. Orange Sunrise is not a particularly high performance propellant and wasn't designed to be. But I can plug pretty much anybody's numbers for pretty much any (reasonable) fuel into the geometry I'm using, with BurnSim, and get something in the low O range (with appropriate nozzle correction). Reality will be determined from flight data. It will be in the upper N to baby O range unless something goes wrong.

I do not expect it to spit a grain.

Really the motor and chemistry questions should be asked in the research forum. I'd likely provide better or at least more complete answers there.

People will probably find my definition of motor sizes to be funny. A small motor is one that a single person can deal with readily enough. A medium motor really should have two or more people moving it around. A large motor needs equipment to move it around.

My long term interest is space shots. This is just a first step - an excuse to develop a smallish medium motor and a rocket to fly it in the East. The next step will be a bit larger motor in a minimum diameter design targeted at the 40-70Kft range. That will bring a whole new range of issues to design for.

Gerald

Some pictures of the nosecone, from a couple months ago...

Gerald

Some pictures of the fin cage and ring assembly. This wraps around the motor case... One can see in the first picture that the electronics bay attaches directly to this assembly. The motor tube actually extends up into the base of the electronics bay coupler.

Also included is a picture of one of the fins and the 6061 aluminum angle brackets. This is the fin core, pre-glassing. It is 3/8" birch plywood.

Gerald

CarVac said:

That's a pretty awesome flame color.

I dunno if discussing this would need to be in the research section or not, but I have a quick question: would adding table salt (sodium chloride) to propellant create a really bright yellow flame from the sodium?

View attachment 86938

Click to expand...

Given the forum rules, it would be better to ask such questions in the research forum.

Thanks for the comment on the flame color. I received lots of positive comments on it when I made that test burn. The picture doesn't really do it justice, though I tried to get the colors close.

Gerald

But can you get the motor to smell like orange?

Can't wait to see the pre/post flight pictures and such, very cool

Last night I put in all the internal T-nuts for retention of the fin angle braces. That was 36 T-nuts, 10-24 thread. I didn't have time to do much tonight after work, so I made a quick assembly/fit test. Here is the lower section of the rocket assembled, with the motor tube installed.

No nozzle, bulkhead, fuel, paint, or launch lugs. Nothing in the electronics bay - not even the allthread. But as it sits in the pictures, the weight is 31# 4oz. That is right around what I was expecting. Nosecone is about 9#. Upper tube is a few pounds. Liner, casting tubes, fuel, probably about 25#. A few pounds for recovery, and a few pounds for electronics... We're probably looking at something in the neighborhood of 80# on the pad.

I'm afraid the camera is distorting the appearance some. It looks much better in person.

The fin mounting arrangement is pretty rigid. I think it will work just fine.

Now I need to fillet the sides of the fin angle support blocks (JBWeld for that), and S-glass or carbon cover the fins. I may still sheath the leading edges of the fins in metal - no decision on that yet. Time will likely make that decision. The original fin design was the same shape and size, but honeycomb carbon with metal leading edge sheath. I figured given the time I don't have, that plywood would work fine for the low supersonic speed expected for this first flight.

Heck, the way things are going, there might be no paint and no video. But I do think I'll get it sufficiently completed to fly.

I do have a major decision to make. My original intent was to have a switch band on the electronics bay, just wide enough to include the lens of the GoPro2 camera. That makes dealing with the camera much easier. But this would reduce the overlap between the tubes and the coupler to about 7 1/2" IIRC. The coupler is double walled bonded, and therefore rather stout. The tubes would be bolted to the coupler by 6 bolts each (or I could go up to 9). The coupler is also attached to the allthread that spans the lower section, via the bottom electronics bay lid. Things would have to go incredibly wrong for the joint to fail between the coupler and lower tube as there are two mechanisms of attachment, either of which should be sufficient by itself. The upper tube just has the bolts though. It has to carry aero loads, and it has a 9# nosecone sitting on top.

What do those of you with experience with similar < Mach 2 rockets think? Is 7 1/2" a long enough overlap with 6.1" tubes? Drogue and main are deployed out the top.

Gerald

I think the "golden standard" in really fast rockets is 1.5-2 calibers on the coupler, so ideally between 9 and 12 inches. However, depending on shear pins you could be fine with the 7.5" it is only a little short. If anyone here would know its Jim Jarvis or Adrian Adamson, ask them to be sure. They have both flown some extreme projects past mach 2

Very nice fin design. Did you use a thicker piece of ply and machine a base onto it so you could have more adhesion? It is a brilliant idea instead of using fillets the whole way around

Plywood fillets should be weaker than standard JBWeld fillets. JBWeld fillets are weaker than the 6061 aluminum angle that I'm using on this one.

The fin cage and ring assembly is tacked into alignment with the tube using 12 small screws flush set into the tube. This assembly was slotted using a router and a box (thanks Jerry O!). This assures the slots in the fin cage and the slots in the tube align perfectly with each other. The slots are in two segments. This allows the rings to stay intact and provides further stiffening of the internal fin support spars. Essentially each fin has a pair of tabs that plug rather snugly (a rubber mallet helps) into the sockets. The pictures in post #10 show that best.

The internal fin support spars are precisely notched and fitted to the rings, and bolted to them with alignment screws. These spars attached to the rings are a pressure fit into the lower tube. There are no gaps at all. Removal without any of the screws or bolts is practically a two person job. It slides in with moderate pressure but it is harder to pull out!

Because of using a 4 1/2" motor in a 6.1" rocket, there isn't much tab depth available on the inside for fin support. The semi-span is 7"... I wouldn't trust the structure with only that much support, not for a rocket that can go fast with the right motor.

Bonded to the outside of the tube are pairs of cove cut plywood strips that match the curve of the tube. These provide a level base for the aluminum angle strips. I haven't done it yet, but these will be filleted in with JBWeld. That will spread the stresses a bit better and smooth the airflow slightly.

The aluminum angle strips were cut to length on a horizontal bandsaw, and then matched up in pairs. The holes for the bolts that extend through the tube were drilled next - pilot and final diameter. Next the strips were stacked in matching pairs in a vice and drilled, so the holes which contain the bolts through the fins align perfectly.

Then the fins were installed in their sockets, and the aluminum angle strips were clamped into final position. The holes next to the fins provided a drilling guide... Once these were drilled, the bolts were added and the clamps removed. Now the holes next to the tube became drilling guides for the tube. A long drill bit - about 8" - was used for this operation. Because the filament wound fiberglass tube was sandwiched between the bonded coved strips on the outside and the precision fit support spars on the inside, the tube drilled clean without fraying. I was a little concerned about that step. If the tube had frayed on the holes, then removal of the ring and fin cage assembly would have been more than a little problematic!

The result is roughly 1.7" of pretty solid fin anchor for a 7" semi-span fin that has just over 6" of unsupported exposed span. It is not the lowest drag arrangement by any means. But it does let me replace fins if I damage one on landing. With a rubber mallet and a screwdriver, the fins remove or install fairly quickly. So transport will be pretty easy.

Gerald

The coupler is double walled fiberglass. The inner coupler is slotted so it fits into the outer one. It extends from perhaps a quarter inch from the top to perhaps four inches from the bottom, and is glued in place with epoxy. I'm not around the rocket right now and don't remember the exact dimensions. The step at the top end forms a labyrinth seal, and the bottom bulkhead butts up against the internal joint. The bulkheads are 3/4" thick at the top and about 1/2" thick for the bottom.

The ring cage has an upper ring which is a snug fit into the bottom of the coupler. The motor tube extends into this ring and stops just above it. Essentially the motor tube provides some additional structural support for the entire lower assembly. At the top of the allthread are coupler nuts. The bottom bulkhead of the electronics bay bolts to this. There are notches in the perimeter of the coupler doubler to allow clearance for putting in and removing the three bolts.

The coupler slides into the lower tube and slips between the top motor ring and the tube wall. It stops when the coupler doubler bottoms out on top of the electronics bay lower bulkhead.

There will be 6 or 9 screws bolting the doubled coupler to the lower tube. The screws go to T-nuts on the inside. There will be 4 pieces of 5/16" allthread connecting the lower electronics bay bulkhead with the upper bulkhead.

The upper tube will slip over the coupler and bolt in place with 6 or 9 screws.

The upper electronics bay bulkhead will hold the Rouse Tech CD3 CO2 system and the Defy Gravity tether system.

I've sketched up a tentative arrangement for the electronics bay and upper bulkhead, but I'm not certain enough yet to start drilling and cutting. I need to decide the switch band issue first.

The internal video will be a GoPro Hero2, with extended battery pack. https://gopro.com/hd-hero-accessories/battery-bacpac/ I need to measure the real battery life. I may have up to about 4 hours available. That might allow me to turn it on, stick it in, bolt it down, and finish prep. That makes for a simpler install as I don't have to access its buttons or read its screen to get it going in the right mode. But it sets time limits...

Tradeoffs...

Gerald

The nosecone is metal tipped filament wound. The threaded rod that the tip screws onto seemed less stable than I wanted, so it is now solidly potted in JBWeld.

The nosecone contains an electronics bay. This is a 3" fiberglass tube. There is a bulkhead at the top end, and aluminum channel runs along the inside. The tray is a long strip of 1/4" plywood. At the bottom end there is a bulkhead joining the tube to the coupler of the nosecone. The resulting trapped volume is filled with expanding polyurethane foam. The bulkhead is prevented from pulling out by a fiberglass ring bonded to the inside of the coupler. The lid, containing the U-bolt, is bolted on with four bolts.

The nosecone is very solid, and essentially pre-weighted to the level needed with the rocket design.

Gerald

More hours of fiddling without much to show for it. Some days are just like that...

I cut the allthread for the electronics bay but haven't drilled the holes in the bulkheads yet. I want to lay everything out first; it prevents surprises.

The lower bulkhead of the electronics bay bolts on top of some coupler nuts at the top side of the ring cage. On the bottom side of the bulkhead there are some washers. It was awkward to keep these in place when assembling, so I switched to studs and nuts instead of bolts. The studs are stuck in the coupler nuts with blue Loctite.

In examining the setup with the motor case installed, I concluded that not quite enough room was available for motor tube thermal expansion. I ended up replacing the 7/8" long couplers with 1 1/4" couplers, made from cutting down 1 1/2" couplers. I think there is adequate room now. I'm allowing for up to about 0.15" of thermal expansion. I didn't compute the expansion due to chamber pressure, but I think I've allowed enough total room.

Since I'm now using studs, it would be difficult (essentially impossible) to pull the lower bulkhead off. So I put a small U-bolt in the center as a finger hook. No problem now.

Assembly order will be to (1) bolt the ebay allthread to the lower bulkhead (2) bolt the lower bulkhead to the top of the ring cage in the upper end of the lower airframe tube (3) slip the coupler in the lower airframe tube so that it nests around the lower bulkhead (4) slide coupler down until the coupler's internal doubler seats on the lower bulkhead (5) rotate as necessary so holes line up between coupler and lower airframe tubing (6) bolt coupler to lower airframe tubing from the outside (7) full ebay with electronics boards and video (8) slip top electronics bay bulkhead in place (9) put nuts on ebay allthread locking upper bulkhead in place (10) make connections necessary for recovery gear (11) slip upper tube in place (12) bolt upper tube to ebay from the outside (12) finish packing recovery gear (13) add nosecone (14) add nosecone shear pins. I think it should be straightforward enough.

The JBWeld fillets on the sides of the aluminum angle support blocks have also been completed.

So there has been some progress but not fast enough. I'm lagging behind where I need to be to be ready for LDRS.

Gerald

Life got in the way. I'm back working on it some though, splitting my time between this rocket and building a CNC machine. Actually the CNC machine is getting more time right now.

Here are some pics. The holes for the GoPro have been cut into the coupler and the allthread rods connecting closing up the ebay have been set in place. Holes for switches have not been cut yet. There is a switch band which isn't attached to the coupler yet. I'm thinking I'll put a hatch over the GoPro controls. It will be easy enough to do - just a segment of the switchband, actually. The hole for the video lens will also be smaller than the one in the double wall coupler. A hatch also allows me the option of leaving out the camera if for some reason I choose to do so. A second hatch with no lens hole would allow this. Anyway I figure that setting the video mode and starting the video will be done while the rocket is horizontal. A hatch is easy to deal with then. All I want to do when hanging off a tower is arm the altimeters.

I was originally planning a pod mounted camera on the outside pointed down. I do not know if I'll do that. But I'm not likely to do it immediately.

I'm also planning to vacuum bag carbon/Kevlar/glass the fins. But again that might not be done immediately. The first flight will be on an M3100 so it will be mild enough that the fins should be just fine without any reinforcement. When I put in bigger N to O 88mm and 114mm EX motors is when the fins will need to be stiffer and stronger.



On the first picture one can see the gap between the upper ring and the wall of the lower tube. The coupler is double walled above this, but single walled below. The lower ebay bulkhead bolts on top of the lower section allthread, just a bit past the end of a baby O 114mm motor. This ties everything from the motor retention on up to the ebay bottom. The big motor tube acts as a lower tube stiffener - completely unneeded for smaller motors. The separate ebay allthread ties the lower bulkhead to the upper one. There, the wall is stepped, forming a sort of labyrinth seal.

The ebay coupler will also be bolted directly to the lower and upper tubes. By the time that is done, this assembly is going to be VERY solid. There are two independent structural systems tying the rocket together. The allthread system, and the bolting together of the tubes. Either by itself is intended to be sufficient.

The pictures are in assembly sequence.

Gerald

PS - That little U-bolt on the lower ebay bulkhead? That is so a person has a place to grab to remove that bulkhead! It wasn't in the original plans, but removal was rather awkward without it!

These pictures should be pretty self-explanatory.



Gerald

Here it is with the tubes assembled, sitting beside the nosecone and the 114mm motor. BTW, the plan is to fly this rocket on a little smaller 114mm N at Red Glare in a few weeks. It might get up to around mach 1.4 on that flight.



Gerald

More pictures - electronics bay bulkhead. This part does not yet have accomodation for wires for the Rouse-Tech CD3 and Defy Gravity Tether, but is otherwise completed. The tether attaches to the eyebolt via quick link. Main attaches to the ubolt via delta quick link and tubular nylon.

The pictures have the largest CO2 cylinder installed that I might ever be tempted to use. I'm expecting to use the next size smaller, a 16g cylinder. But the nosecone and rocket are heavy and I want to make sure they separate. So, I made the bulkhead be able to take the next larger cylinder.

A cardboard tube (38mm casting tube or liner) is used over the CD3 to direct the ejection gasses to the nosecone end. Even though the dbag will be anchored down, I don't want to be blowing gas around it so much which would try to push it out. It wouldn't deploy just from that, but the tube should make ejection gentler for the main and its dbag. The main itelf gets released later via the tether separating and allowing the drogue on the nosecone to pull out the dbag.

The cardboard tube will get secured in some fashion to the bulkhead or the side of the upper tube. Heck, even tape would work for that.



Gerald

Do you realize that the CO2 comes out from the bottom-most (closest to the CO2 canister) set of holes in the CD3? The placement of that tube would direct more gases down, below your deployment bag, than up.

If you want any kind of performance, why are you using Orange Sunset? Just wondering...

Yep, the CO2 comes out the bottom of the upper section. The tube provides a clear region that does not get blocked by the chute and its dbag. It provides a low resistance passage for the gas to pass to the top of the dbag and then out once separation has occurred. It is not possible for the tube to direct the gasses down when it provides a low resistance passage up! Without the tube, the ejection gasses will attempt to pack the dbag and chute upwards.

I'm not using Orange Sunset... The propellant shown in the first post is an Orange Sunrise variant, which is a propellant developed by me. The rocket will never fly on that propellant - it wasn't stable under storage. Too bad really. It was pretty insensitive to Kn from the 150 to 450 range, with nearly constant slow burn rate over that range. Super smooth steady burn. The mach diamonds were pretty much frozen in place. Pressure curve very flat without ripples. But there were processing issues and storability issues that were unacceptable.

I have other variants under development using different chemistry which have higher density, good stability/storability, and otherwise fairly nice properties. At MDRA I'll likely fly Sunrise 10b or Sunrise 13, depending on which motor I get to fly. For reference, the propellant in the picture at the top of the thread was Sunrise 3. There has been a lot of work and a lot of tests since then, both static and flight tests.

Here are some pictures from some more recent tests, L and M motors:



Sunrise 9, Sunrise 9, Sunrise 11 (a slow burn), Sunrise 10b, Sunrise 10b.

The two flight pictures are Jerry O'Sullivan's rocket and Al Anderson's rocket, respectively. These are 7 1/2" diameter to give scale to the pictures. This is the propellant I'm likely loading into the 88mm backup N motor for Red Glare. The 114mm N is undecided yet.

Gerald

incredible thread, please keep posting Gerald... Fantastic to read! What a great job...

What are the blue motors? Surprisingly low flame signatures on those motors.

I have been in the process of developing two potential propellants for use in altitude launches, for a Black Rock project where one can actually put a rocket up to decent altitude. Unlike the east... One approach is a propellant with moderately high density and a little slower than average burn rate. The other approach is something that gives up some performance and density, for even slower burn rate. I do not want average or faster burn rate as I want to keep the rocket under mach 3 to reduce the heating and structural issues. I'm not trying to re-invent a CTI N5800! At this point I have no conclusion on which propellant direction I might use. There have been numerous tests, and one abandoned branch. Those pictures show some of the tests from the last few months.

The last two pictures are of 3500 (AMW case) and 4500 (old Kosden East case) 75mm Sunrise 10b flight tests with conventional bates grain configurations. These particular tests were at MDRA. Those last two pictures required a fair bit of photoshopping. The exposure compensation was set too high so the pictures were rather dark. They still are a bit dark I think. There were plenty of people there who saw those flights. They can comment on what the flames really looked like. I only get to see many of the tests through a camera or video viewfinder. I think this is close though to the visual impression one gets. The flame is transparent and the mach diamonds are even more apparent in real life. The smoke track is present but low compared to most commercial and EX motors. We achieved greater altitude on those launches than normal for those case sizes, by ratio of the increased propellant density.

If I have the rocket ready in time, and if the waiver is available and conditions are suitable, I'll be launching on an N motor using Sunrise 10b or a variant of it. It will be either an 88mm or a 114mm. The 114 should break mach easily, but I'm a bit less sure of the 88. My target launch day is Friday at Red Glare, before things get too hectic. But our group has three large projects to launch and we are helping each other out so what goes up when is really TBD. The other projects are Jerry O'Sullivan's two stage IRIS, and Al Anderson's Bubba, shown in the right-most picture. For those who haven't seen it, and even those who have, you do NOT want to miss Jerry's next flight!

I've wondered if people were even interested in this project, there has been so little feedback. I appreciate the posts!

Gerald

What is the differences between all the different sunrise formulas? Just curious...