View Full Version : NASA Study Summary: "Study of an Evolutionary Interim Earth Orbit Program"
luke strawwalker
04-25-2011, 06:04 PM
Here's an interesting report from 1971 entitled "Study of an Evolutionary Interim Earth Orbit Program". It's basically calling for four more Skylabs, each one built successively after the others, designed for 1 year missions, and launched every 2 1/2 years, so that lessons learned from each station can be incorporated into the design of the next. The stations were to be serviced and resupplied by Apollo CSMs, possibly uprated to the four-man variant. The launch vehicle for the stations would have been the INT-21 variants of the final four Saturn V's, which were to be freed up by cancelling the lunar missions after Apollo 15. The crews and resupply craft would have been launched by either (uprated) Saturn IB's, Titan III-M with a hammerhead adapter section for the CSM (though this vehicle had insufficient performance to carry additional supplies and thus was eliminated) or a new Saturn IB variant using a three-motor cluster of Titan III-M SRMs for it's first stage with an S-IVB from Saturn IB for the second stage. The stations themselves would have been constructed similar to Skylab, using the S-IVB stages in the 'dry workshop' configuration, launched atop the two-stage Saturn V (using the S-IC and S-II stages similar to Skylab). The SRM/S-IVB launcher was shown to be cheapest and have the greatest lift capacity of any of the logistics/crew launchers examined.
The whole purpose of this proposal was to keep NASA "occupied" during the long gap between the final Skylab flight and the first shuttle flights leading up to the space station (which at the time was supposed to go hand-in-hand with the space shuttle) though no mention was made of the ASTP flights at the time (probably before the idea was even floated... )
At any rate, it's an interesting "might have been"... the last of the missions would have overlapped shuttle (well, by the preliminary timelines anyway-- since shuttle was delayed probably not had this proposal actually been done). Also ramps up the reality of a 3 SRM clustered first stage replacement for Saturn IB... by this time the 156 and 260 inch SRMs must've been well and truly dead, for no mention of them whatsoever was made.
Enjoy! OL JR
luke strawwalker
04-25-2011, 06:05 PM
The first pic is the interim orbital workshop... the Mission A space station from this proposal.
Pic two is the Skylab showing its arrangement of solar arrays to provide sufficient power to the station.
Pic three is the second interim space station from the Mission B. It basically is showing how many solar arrays can be crammed onto an S-IVB with some careful packaging... (deploying them might be another matter... LOL
Pic four is the third and fourth space station from the C and D missions. These would use solar power augmented by a nuclear/Brayton cycle generator to provide the bulk of the electrical power. They would also use advanced "closed loop" life support systems as demonstrators for the future permanent space station design to go hand-in-hand with shuttle.
Pic five is the INT-21 launch vehicle as defined for this report.
More to come! OL JR
luke strawwalker
04-25-2011, 06:06 PM
Pic one is not actually from this study, but it's relevant to it... it's the INT-21 from the Saturn improvement studies relating to intermediate vehicles.
Pic two is not from this study, but again, it's relevant. It's the graphic of the various proposals for SRM Saturn IB first stages using the 120 inch Titan III UA-1205 or 1207 SRMs clustered for a first stage with the S-IVB on top of it, lofting the CSM and whatever cargo module would have been used. This version was capable of 55,000 lbs to LEO and was recommended over the Saturn IB which could only deliver about 33,000 lbs to the same orbit, or Titan III-M which could only deliver 25,000 lbs.
Pic three is from the 1961 Grand Central Rocket Co. Very Large Solid Rocket study, again of a three-120 inch SRM first stage topped by liquid propellant stages, in this case, the 4 J-2 engined early C-3 S-II stage which was also to be 260 inches in diameter like the single J-2 powered S-IVB, and this particular iteration also uses the S-IV upper stage powered by what was to become six RL-10's (the 220 inch stage). The first stage is very similar to what would have likely been built for such a vehicle.
Pic four is showing the head end of the three 120 inch SRM cluster, where it would join to the S-IVB. As you can see, three 120 inch SRMs fit nicely within the 260 inch OML of the S-IVB stage, making for a streamlined rocket and easier engineering of the fwd skirt of the SRM first stage to mate to the S-IVB upper stage.
Pic five is the side view of the 3 SRM first stage.
More to come! OL JR
luke strawwalker
04-25-2011, 06:07 PM
Pic one is the mid section of the three motor cluster foldout from the previous pic in the last post, showing the relevant dimensions.
Pic two is the nozzle end of the three motor cluster foldout, with dimensions. This version would have been heavy but probably could have been handled in the VAB and crawlers, with any luck.
Pic three is the complete foldout showing all three views. This is the early GCR proposal, but the final product would have been quite similar, most likely, only differing in the length of the UA-1207 SRMs used on Titan III-M instead of the three-segment GCR 120 inch proposed SRMs here. The final stage would have undoubtedly had some kind of forward skirt structure to link the spider beams connecting the three head ends of the SRMs together and transfer the thrust through a ring-frame and hat-section skin-stiffened skirt into the cylindrical skin of the S-IVB interstage, as well as providing a joint plane for connection of the S-IVB interstage with the upper end of the SRM first stage to bolt them together. There may well have been an aft skirt as well, to cover and protect and support control and monitoring equipment in the aft end of the first stage, and possibly support additional aerodynamic fins to augment the vehicle stability early in flight, as with Saturn IB and Saturn V. Six Saturn IB fins would look good on this vehicle! Another likely difference from the proposal shown here would be the addition of steering fluid tanks nearly identical to those used on Titan III... the "steering vanes" of this early GCR proposal were outdated nearly before the ink was dry on the proposal! Titan III had successfully used and proven the steering fluid injection system many times by the time this vehicle would have flown, and there would be no reason whatsoever to use a different kind of system. It would have required the installation of three small cylindrical steering tanks nestled in between the SRM's in the first stage cluster, mounted probably near the middle to minimize CG changes to the stage during flight (since the SRMs burn from the center outward and had much smaller CG changes than a comparable liquid propelled stage. Any model would be incomplete without them...
That's it for this one! Later! OL JR
Titan III-M with a hammerhead adapter section for the CSM (though this vehicle had insufficient performance to carry additional supplies and thus was eliminated)
Any drawings of this proposal? I think it would make for a wickedly cool concept scale model.
Bill
There may well have been an aft skirt as well, to cover and protect and support control and monitoring equipment in the aft end of the first stage, and possibly support additional aerodynamic fins to augment the vehicle stability early in flight, as with Saturn IB and Saturn V. Six Saturn IB fins would look good on this vehicle!
And it might look sort of like a Centuri/Semroc Defender.
Bill
luke strawwalker
04-27-2011, 10:35 AM
Nope, no drawings that I know of... I have a pic of a scale model someone did over on the NASA model thread on nasaspaceflight.com/forums... Think it's the same guy that did all the Saturn I/IB's and stuff...
Here's all I could find right now... I'll have to find it later... gotta run errands...
OL JR :)
Nope, no drawings that I know of... I have a pic of a scale model someone did over on the NASA model thread on nasaspaceflight.com/forums... Think it's the same guy that did all the Saturn I/IB's and stuff...
The second picture would seem more like it, though the "hammerhead" is longer than I was expecting; the first one implies a 10 foot diameter capsule.
Bill
blackshire
04-27-2011, 09:28 PM
If memory serves, the 1970s-vintage novel "Lucifer's Hammer" (about a comet striking the Earth) featured a quickly cobbled-together Titan IIIC/Apollo CSM combination very similar to the Titan IIIM/Apollo CSM, which was orbited along with a separately-launched Soyuz to form the international "Hammerlab" observatory to observe what was originally thought to be a very close flyby of Earth by the comet's nucleus.
luke strawwalker
04-28-2011, 12:30 AM
The second picture would seem more like it, though the "hammerhead" is longer than I was expecting; the first one implies a 10 foot diameter capsule.
Bill
No, I think the first one was for a four-engine core proposal called "Barbarian" or something to that effect... It would have had the core enlarged from the Titan II's standard ten foot diameter to about 13 feet, which would have made the 154 inch diameter Apollo SM a direct mate-up to the upper stage. Note the core of that vehicle has four nozzles... I think they just doubled up on the LR-87's IIRC... I know I read about that proposal a year or two ago on astronautix.com...
Lemme see if I can find that model pic... I'm not having much luck finding it on my hard drive...
More later! OL JR :)
No, I think the first one was for a four-engine core proposal called "Barbarian" or something to that effect... It would have had the core enlarged from the Titan II's standard ten foot diameter to about 13 feet, which would have made the 154 inch diameter Apollo SM a direct mate-up to the upper stage. Note the core of that vehicle has four nozzles... I think they just doubled up on the LR-87's IIRC... I know I read about that proposal a year or two ago on astronautix.com...
You are quite right. I totally failed to notice that the core is significantly larger in diameter than the SRBs.
I was hoping to see a drawing with a hammerhead not much longer than the SM, but now realize that the large nozzle of the SM engine requires a significant length of straight 154" tube between the SM and the Titan booster.
Bill
luke strawwalker
04-28-2011, 10:26 PM
Bill,
Here's a couple more pics from Mike Robel over on nasaspaceflight.com/forums. I had the pic of his excellent model saved on my hard drive but it somehow disappeared in the fray of reorganizing everything... I looked for about two hours last night on the forum trying to find it again, and after having no luck, PM'd him and he graciously sent me a copy, along with a few other things, including the neat photoshop by our own Wes Oleszewski, aka Dr. Zooch...
This is the Titan III-M topped by an adapter to support the Apollo CSM. The study showed that this version was about 10,000 lbs or more shy of the lift performance they were advocating for combined resupply/crew rotation missions to the interim space stations, and so they eliminated this version fairly quickly in their studies, followed shortly thereafter by the Saturn IB which was still incapable of the kind of cargo lift they were advocating to support the stations.
I guess part of the answer to that was the FOUR 120 inch SRB Titan III... That would have been a real beast... The scale model pic I posted before can be clearly seen to have FOUR SRM's attached... BUT, if you need THAT much lift, as this study seemed to imply was required, then you might as well drop the Titan core vehicle altogether and simply bolt the four SRM's together into a single clustered first stage, and top it with the S-IVB hydrogen upperstage and get some HD lift capability to orbit with less engines and staging/separation events, and without all the hypergols... (except the CSM anyway).
Enjoy! OL JR :)
Here's a couple more pics from Mike Robel over on nasaspaceflight.com/forums.
The CSM appears to be overly large in the Dr. Zooch composite picture. But that was the kind of wicked look I had envisioned.
The model in the second picture appears to combine an Apogee Apollo capsule and LES with an Estes Titan-IIIE kit. The scales of the two are somewhat close, but not the same. Few would know the difference though.
I had to look this up. The SM engine nozzle is just under 100" in diameter, so it could hide within a 120" Titan-sized tube, allowing a short reducer to be attached directly to the SM.
Bill
luke strawwalker
04-29-2011, 03:47 PM
The CSM appears to be overly large in the Dr. Zooch composite picture. But that was the kind of wicked look I had envisioned.
The model in the second picture appears to combine an Apogee Apollo capsule and LES with an Estes Titan-IIIE kit. The scales of the two are somewhat close, but not the same. Few would know the difference though.
I had to look this up. The SM engine nozzle is just under 100" in diameter, so it could hide within a 120" Titan-sized tube, allowing a short reducer to be attached directly to the SM.
Bill
I noticed that too... looking closely at the pic, I think that it's a photoshop of a standard Titan IV with the big fairing, spliced in with a CSM/tower shot... that's why the CSM is "too big" for the rocket.
Not sure how Mike built his rocket... I know he's got a ton of them and some REALLY neat prototypes/paper rockets.
Remember, the Apollo CSM was 154 inches in diameter and the Titan was 120 inches, so that's less than 3 feet difference, or only a 1.5 foot radius increase from one end of the adapter to the other... pretty small difference when you think about it. I don't know how much room there would be in the front end of a Titan upper stage for the SPS nozzle-- plus the required clearance at separation... At any rate, an Apollo WOULD look neat on top of a Titan III, but it wouldn't be a terrific payload carrier... just a basic LEO taxi kind of vehicle AT MOST...
The true "workhorse" was the four Titan IV SRM cluster first stage topped by the S-IVB-- 55,000 lbs to orbit, half again what Saturn IB could do...
Later! OL JR :)
mkrobel
05-01-2011, 09:17 AM
Thanks for mistaking the Titan IIIC/Apollo for the Estes/Apogee combination kit bash. But it is a 1/144 kitbash of the Realspace Models Titan IIIC + their 1/144 CSM. Glenn made a special adapter for me. On the other hand, I do own the Ested Titan IIID and the Apogee Saturns (unbuilt) It would be an easy conversion...
If only I could come up with a reliable way to parallel stage.
luke strawwalker
05-01-2011, 11:10 AM
Thanks for mistaking the Titan IIIC/Apollo for the Estes/Apogee combination kit bash. But it is a 1/144 kitbash of the Realspace Models Titan IIIC + their 1/144 CSM. Glenn made a special adapter for me. On the other hand, I do own the Ested Titan IIID and the Apogee Saturns (unbuilt) It would be an easy conversion...
If only I could come up with a reliable way to parallel stage.
With the new Q2G2 low current ignitors from Quest, igniting clusters is nearly as easy as single motors nowdays... as for dropping the boosters, there's a number of good designs out there for linkages that will reliably drop the boosters (and I have another one in mind myself that I'm tinkering with). So don't let that stop you!
Later! OL JR :)
Thanks for mistaking the Titan IIIC/Apollo for the Estes/Apogee combination kit bash. But it is a 1/144 kitbash of the Realspace Models Titan IIIC + their 1/144 CSM. Glenn made a special adapter for me. On the other hand, I do own the Ested Titan IIID and the Apogee Saturns (unbuilt) It would be an easy conversion...
Not being familar with the Realspace models, the detail on the Apollo BPC said "Apogee" to me.
Welcome to the forum, BTW.
Bill
The August 1970 issue of Model Rocketry Magazine http://www.ninfinger.org/rockets/ModelRocketry/Model_Rocketry_v02n11_08-70.pdf was the introduction to parallel staging for many of us. In his column, The Escape Tower, Bob Parks describes his construction and flight of a Titan III-M with working solid rocket boosters.
I found this article very inspiring, but did not build one myself for several reasons:
I did not have an unbuilt Estes K-21 Gemini-Titan kit.
I did not have or know anyone who had a launch system capable of reliably igniting a cluster of four motors.
Four motors in one flight seemed awfully expensive at the time.
But the main reason was that I was chicken. There, I said it. The model seemed like a disaster waiting to happen. The main problem was that Bob's design barely held the boosters onto the core. And it depended on the higher thrust of B14 motors to keep the boosters from falling off prematurely. Should one of the B14s be late to light, the main vehicle is likely to vacate the pad without it, leaving it behind to skywrite wildly.
More to come...
Bill
mkrobel
05-02-2011, 06:49 PM
I vaguely remember that article. At about that time, I did convert a Gemini-Titan II to the MOL configuration, mounted D engines in the strap-ons. Test flew the core while I was trying to figure out how to hold the boosters on. Launched in from the back of my kid brothers elementry school, and it promptly flew into the canal/swamp/forest behind the school and I couldn't find it. About 6 months later two kids showed up at my doore with the remnants. Never tried with that one again.
I found an article years later with a GEO-SAT LV converted to parallel staging, but never finished or flew it. It is still in the big model rocket box in the closet together with the Estes Mercury Redstone (partially built), Atlas (not built), pieces and plans to build the Gemin-Titan with the BT-70 tube (and a Titan IIIM veresion), 1/100 saturn IB (partial), 1/100 Saturn V (built and flown), another GEO-SAT LV (unbuilt), 2 Black Brant IIIs (unbuilt), Semroc Mars Lander, (unbuilt)m, 1/100 Little Joe II (built and flown), 2 Space shuttles (with the ET, and so on, 1 partial, 1 unbuilt), Mars Mini-Lander (flown) awaiting a better paint job, two of the follow on Mars Lander thing (I forget what it is called, not built), and maybe a couple other ones. In their own boxes, the 1/70 Apogee Saturn IB and Saturn V.
Everynow and then I think about taking them out and flying them, and then I stop. :)
Not currently for sale.
Though I never built a Bob Parks Titan III-M, I did ponder quite a bit on ways to improve upon his design to make it safer and more reliable.
Nothing more came of it until the early 90s. While hanging around on the discussion boards of the Prodigy online service, I came across a question about parallel staging in the hobbies area. Not having possession of Model Rocketry Magazine at the time and this being long before the ninfinger archive became available, I summarized what I could remember about Bob's article and listed the problems with the design. We bounced some ideas around. I really wish there was some way to find out with whom I had exchanged those messages. I think he was a kid at the time, but even if that was the case, he should be old enough to BAR by now.
My best concept at that time was to attach two short lengths of launch lug on the core stage near the ends of the booster. At the tail end of the booster is a short strip of wood topped with a slightly longer piece of 1/8" dowel with the extra length extending forward from the end of the wood to engage the rear launch lug from behind. A similar fixture facing aft would be attached to the nose cone of the booster to engage the forward lug from the front. The idea was that as long as the nose cone stayed on the booster, the assembly would be locked onto the core. Such a strap-on booster would more likely than not stay attached in case its motor does not light, but that was not guaranteed; there was still a chance that if the booster misfired, it may be dragged down by its set of clips and pulled loose from the core. Whether it ignited late or not, the flight would be interesting due to the nose cone of the booster remaining attached to the rapidly accelerating core. But it no longer demanded B14s in the boosters.
At the time, I had yet to be exposed to the joys of flying with a club, with access to good launch equipment and a number of knowledgeable people to discuss concepts like this. So again, I did not pursue it. My BARdom will have to wait for more years to pass.
More to come...
Bill
mkrobel
05-02-2011, 08:07 PM
Actually, that was very much how the GEO-SAT LV was convereted to parallel staging. I think I have the article in my files.
While I was browsing the magazine rack at the local Book Stop, a copy of High Power Rocketry Magazine caught my eye. "What the heck is this?" I wondered. That magazine stuck to my fingers and went home with me that day. I would begin monitoring the magazine rack and buy each new issue as it showed up. After several years of this, I finally decided to take the plunge and joined both NAR and Tripoli. But it would be several more years before I got active in the hobby again. The local NAR section met Friday evenings on the edge of a region heavy with nightlife traffic, not an appealing proposition. The tipping point was when the section hosted a NARCON and their meetings were on Saturday afternoons mere miles from home; it was time for BARdom.
One of the first things I did was to look into the state of the art of parallel staging techniques. I was quite disappointed to see several efforts much like the dowels and launch lugs approach in my last post. Although they seemed to work, I had already ruled out that concept for several reasons:
The possibility mentioned in my previous post that a booster misfire may result in the clips remaining attached to the igniter and causing the booster to come off.
There is a slight possibility that drag in combination with vibration might cause a misfired booster to separate.
Newton says that for every action there is an equal and opposite reaction, but blowing the nose cone is not guaranteed to disengage both dowels. Having either one remain attached is a problem.
Dowels glued to wood strips do not make for a very strong attachment. It should be OK for black powder, but will not scale up well to mid and high power.
The design is good if things only move in line with the long axis of the rocket. Forces in any other direction will tend to break the dowel loose resulting in a spectacular failure, or at the very least, a needed repair before a repeat flight.
For a while, Ray Dunakin sold hardware for parallel-staged boosters. His design looked promising, but was targeted for mid power and low end high power only. It was an expensive solution and not available for smaller models. The main problem is that he only made those for a short time.
There have been several high power projects which featured separating parallel boosters. But those approaches used pyrotechnic release techniques not suitable for smaller models.
More to come...
Bill
CPMcGraw
05-03-2011, 10:31 PM
Although it probably limits the smallest diameter that a booster can be built, what I've been thinking about is an internal piston that has limits on the distance it can move. The forward-sliding action of the piston would be contained within the booster, and would not be affected by external aerodynamics.
The piston would connect to some form of "hook" and "latch" system that holds the booster to the core near the top. This could still be a dowel-and-lug mechanism, as the purpose here is only to keep the booster up against the core. The bottom of the booster has to have a set of "stops" to keep it from moving forward or rearward through ejection, but allow the booster to fall "outward" after the upper "hook" disengages at the top.
The ejection pressure could be vented from the piston core after the piston reaches the upper limit stop, and out near the top of the booster. If you point the exhaust toward the core, it should help "push" the top of the booster outward. Think of the Scout here, and how the vent hole was supposed to "upset" the ballistic trajectory and cause the tumble.
Although it probably limits the smallest diameter that a booster can be built, what I've been thinking about is an internal piston that has limits on the distance it can move. The forward-sliding action of the piston would be contained within the booster, and would not be affected by external aerodynamics.
The piston would connect to some form of "hook" and "latch" system that holds the booster to the core near the top. This could still be a dowel-and-lug mechanism, as the purpose here is only to keep the booster up against the core. The bottom of the booster has to have a set of "stops" to keep it from moving forward or rearward through ejection, but allow the booster to fall "outward" after the upper "hook" disengages at the top.
The ejection pressure could be vented from the piston core after the piston reaches the upper limit stop, and out near the top of the booster. If you point the exhaust toward the core, it should help "push" the top of the booster outward. Think of the Scout here, and how the vent hole was supposed to "upset" the ballistic trajectory and cause the tumble.
Can that piston be rigged to push off the nose cone and deploy a parachute or streamer as well?
I would be concerned about having a dark exhaust mark on the core stage opposite that vent. Maybe you can come up with a way to claim some mission points for it?
Bill
CPMcGraw
05-04-2011, 05:58 PM
Can that piston be rigged to push off the nose cone and deploy a parachute or streamer as well?
Don't see why it couldn't. Make the NC part of the piston assembly itself, using a dowel at the center (or offset) to connect the two. The streamer could attach to the dowel, and be protected by the piston below. No wadding required.
I would be concerned about having a dark exhaust mark on the core stage opposite that vent. Maybe you can come up with a way to claim some mission points for it?
Hmnnn...
Don't know about the mission points, but it should look realistic!
For core protection, maybe a sticky-back Tyvek sleeve around the core at the level of the exhaust port?
mkrobel
05-04-2011, 07:31 PM
I found this link on line, but no instructions. It looks sturdier than the GEO SAT LV plans I am looking for...
http://www.drsuesrocketworks.com/Darkbird.html
While I was browsing the magazine rack at the local Book Stop, a copy of High Power Rocketry Magazine caught my eye. "What the heck is this?" I wondered. That magazine stuck to my fingers and went home with me that day. I would begin monitoring the magazine rack and buy each new issue as it showed up. After several years of this, I finally decided to take the plunge and joined both NAR and Tripoli. But it would be several more years before I got active in the hobby again. The local NAR section met Friday evenings on the edge of a region heavy with nightlife traffic, not an appealing proposition. The tipping point was when the section hosted a NARCON and their meetings were on Saturday afternoons mere miles from home; it was time for BARdom.
One of the first things I did was to look into the state of the art of parallel staging techniques. I was quite disappointed to see several efforts much like the dowels and launch lugs approach in my last post. Although they seemed to work, I had already ruled out that concept for several reasons:
The possibility mentioned in my previous post that a booster misfire may result in the clips remaining attached to the igniter and causing the booster to come off.
There is a slight possibility that drag in combination with vibration might cause a misfired booster to separate.
Newton says that for every action there is an equal and opposite reaction, but blowing the nose cone is not guaranteed to disengage both dowels. Having either one remain attached is a problem.
Dowels glued to wood strips do not make for a very strong attachment. It should be OK for black powder, but will not scale up well to mid and high power.
The design is good if things only move in line with the long axis of the rocket. Forces in any other direction will tend to break the dowel loose resulting in a spectacular failure, or at the very least, a needed repair before a repeat flight.
For a while, Ray Dunakin sold hardware for parallel-staged boosters. His design looked promising, but was targeted for mid power and low end high power only. It was an expensive solution and not available for smaller models. The main problem is that he only made those for a short time.
There have been several high power projects which featured separating parallel boosters. But those approaches used pyrotechnic release techniques not suitable for smaller models.
More to come...
Bill
I found this link on line, but no instructions. It looks sturdier than the GEO SAT LV plans I am looking for...
http://www.drsuesrocketworks.com/Darkbird.html
Thanks. I was not aware of that one.
Bill
Years of experience in product development demanded that an organized approach be taken to designing what I can consider a good parallel staging system. The design goals in decreasing order of importance are:
1. Safety and reliability. These two go together as any failure may result in pieces of rocket flying wildly through the air in unpredictable directions. Something to be avoided. The requirement here is obvious: the booster must be positively locked to the core stage until it is supposed to separate.
2. Wider motor choice. Again, a positive lock of the booster to the core allows the use of something other than B14s in the booster and lower thrust motors in the core stage.
3. Realistic appearance during operation. Real boosters separate from the core in a "flower petal" pattern. Having the forward end of the booster tilt outward when separating also helps to prevent its recovery system from tangling with the core stage.
4. Inexpensive and easy parts availability. Use commonly available parts whenever possible. If custom parts are necessary, they should be able to be easily fabricated using safe practices and no hard to get or expensive tools.
5. Inobtrusive. The staging hardware shall not be so large and unwieldly that it overwhelms the appearance of the vehicle, especially if it is a scale model.
6. Scaleable. Ideally, the design should be applicable to the smallest model up to a high power project. Larger high power projects may need the extra strength and continue to use pyro mechanisms where there is not a limiting size or weight limit.
7. Easy of flight preparation. The ideal is for parts to simply plug together and not require more than one person (two hands) to do it. And it should not take much longer to prep than n+1 separate simple rockets or a cluster of n+1 motors, where n is the number of separable boosters.
8. Reproduceability. It would be very nice if the design can be sold in kit form such that a person with average skills can put it together and get it to work.
From the competition world comes the concept of the burn string to hold parts together. I am not even going to consider that as I do not like the idea of igniting anything other than motors. Another problem is that they are neither fast nor easy to prep.
In pursuit of goal #3, an idea came to me early on to put a short spring, such as a piece cut from the one in a ball-point pen, between the front end of the booster and the core so that once released, the booster starts to peel away, front end first.
Then I thought, what if I attach that spring to the core stage and put a small nail or screw inside that spring to poke through a small hole on the side of the booster? Something like an electrical spade connector can be used to slide over the head of the nail or screw on the inside of the booster tube to lock the booster into place. That was the original concept for the forward attachment and it languished in my head for years. Spade connectors for smaller than a #6 stud are not easy to find, so this idea is too big for very small models.
The rear attachment had to be something which would hold the booster in place, releasing it only if the front end of the booster swung out. No obvious way of doing this, but I thought it would be easy once the front attachment problem was solved.
The project was essentially frozen at this point until MarkB started building his Vostok http://forums.rocketshoppe.com/showthread.php?t=7912. I really want one with shedding boosters, so I started putting a lot of thought into this design again.
Research into new ways to implement the attachment fixtures involved several trips of several hours walking through big box hardware stores looking for things to misuse.
I think I finally have something I can build and flight test. It is very simple and the only part fabrication is done with a hacksaw. Scrapping the screw or nail head and spade connector idea for the forward attachment allowed visualization of a simpler approach which also can be adapted for a low power implemention of the aft attachment; more study will be needed to see how well it scales up.
More to come...
Bill
mkrobel
05-04-2011, 08:28 PM
Here are the GEOSAT LV conversion plans. Probably okay for a semi-scale or fictional bird, but not so good for a Titan III or other scale rocket.
OK, the file is too large to upload, so I shall have to break it up and load it tomorrow.
Edit: Even if Just scan seperate sheets, the file is still to large to post to the forum. If anyone wants it, PM me, and I will e-mail it to you.
Attached is one of the graphics pages.
mkrobel
05-05-2011, 06:10 PM
And the other page of graphics.
...and here is the design...
Forward Attachment.
On the core stage, near where the front end of the booster would be, mount a staple. Not the familiar rectangular office staple, but a U-shaped one like those used to run wiring along a wall. For a small model, the staple should protrude just over 1/2" from the tube. It must be perpendicular to the length of the tube so that viewed from the end, it looks like a miniature croquet wicket. A small piece of wood or a thick centering ring will be needed on the inside of the tube for a secure mount.
Cut a small slot near the front end of the booster tube just large enough to slide over the "wicket." Glue two short pieces of launch lug on the inside of the booster tube, one just in front of and the other behind the slot. A short length of dowel or wire attached to the nose cone slides into the "wicket" (and through the guiding and reinforcing launch lugs) to hold the front end of the booster in place for launch.
Glue a short piece of compression spring to the outside of either the booster or the core stage near the attachment so that it will be caught between the booster and the core. An easy source for this part is the common retractable ball point pen. A small piece of soft foam may be substituted. This tiny part is vital so that the front of the booster pivots away from the core when it is released.
Aft Attachment.
Get a small cup hook. If that is not available, get a screw eye. Cut the open end of the hook or eye with a hacksaw so that you have about a 150 degree opening relative to the surface the hook or eye is to be attached. Use some emery cloth to smooth rough edges from the cut. Insert this hook into the base of the booster with the opening facing down. If the booster is based on a BT-55 or BT-50, an AR-2050 or AR-5055 style centering ring may be enough to serve as an anchor on the inside of the booster tube. Otherwise, back up the tube with a small piece of wood.
Attach two staples at the aft end of the core stage. They should be separated by slightly more than the thickness of the hook on the booster. The rearmost staple should protrude just enough so that the booster hook can fit onto the "wicket." The other staple should stick out a little further as it will bear the thrust of the booster. As with the forward attachment, backing is needed inside of the tube.
Construction notes.
The attachments have been described starting with the front one to aid understanding of how the system works. In practice, I strongly recommend that the aft attachment be installed first. It is much easier to ensure that the staple and slot of the front attachment are properly aligned if the aft attachment is complete.
Flight preparation.
Prepare the booster as you would an ordinary rocket. Before sliding the nose cone into place, point the front end of the booster away from the core and insert the hook into the lower of the two "wickets". Pivot the booster into place and slip the slot over the front "wicket." Seat the booster nose cone making sure that the retaining dowel or wire is in the "wicket." That is all there is to that.
Unless parts are laser cut or extreme care is used in construction, it is likely that the spacing between the attachments will vary enough between different sets of boosters and their attachments so that a booster can only fit in one set of attachments. Mark the booster and attachments as they are installed for reference during flight preparation.
Because of the unique geometry involved, a Vostok booster cannot simply blow its nose, so there is more work left to do...
Bill
mkrobel
05-08-2011, 07:51 PM
Seems to me that these would work, especially if they were placed inside the body tube so that only the "hook" portion protrudes and the slit is properly aligned.
http://www.apogeerockets.com/glider_pod_hooks.asp
Seems to me that these would work, especially if they were placed inside the body tube so that only the "hook" portion protrudes and the slit is properly aligned.
http://www.apogeerockets.com/glider_pod_hooks.asp
That is a good idea for gliders, but I wonder whether the added weight may be a problem. If the glider half replaces nose weight which would have been needed anyway for trimming, it would not be an issue.
However, one of the goals is not to depend on rare parts. There is no way to guarantee that Tim does not decide to stop making these. Plus I really want the booster to swing out before dropping off.
While buying parts for my prototype, I discovered that either the round end of a cotter pin or the loop spring end of a safety pin may be a good replacement for the lower wicket of the aft attachment, so I bought some of each to try.
Bill
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