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View Full Version : Farside and 3-stage considerations


Doug Sams
04-22-2007, 11:37 AM
Oooooo... thanks Doug! I just went and checked out the Farside X from your mention and that looks like something I'd enjoy too... I've been pondering doing my first staged build here lately and that's lookin like a pretty good place to start! Already got the noses for it to boot!(Continued from another thread.)

Here are some considerations for 3-stage rockets including the Farsides. I did these on my Comanche and on my Uber-Tuber.

The first consideration is the 1st stage motor. Since B14's are no longer available, you will need something else. Trying to fly a 3-stager this heavy on 1st stage B6 or C6 motors will result in unsatisfactory results. It will crawl off the rod and likely severely weathercock. A more potent 1st stage motor is in order and that means a 24mm C11-0 or D12-0.

The next concern is motor retention in the 1st stage. I've seen too many cases where, at staging, the 1st stage motor was ejected by the staging pressure while the booster section stayed stuck to the next stage with a fried booster as the result. So you need some way for the booster to be hard fixed to the motor.

On my Uber-Tuber, I simply made the 1st stage airframe and motor tubes long enough to completely envelop the motor so that there was room aft for a motor block. But to stay faithful to the dimensions of the Farside/X and Comanche, a motor hook is needed. And this will need to be external since these 1st stages, with 24mm motors, are minimum diameter. I've had good results using piano wire and a bit of glass cloth followed by FNF. Here's a little more info on that subject: http://home.flash.net/~samily/stuff/tailconehook.html

Venting the 1st stage is critical since you can't use tape-together staging with two different diameter motors. In the drawing below, you can see there's about 1/4" gap between the S1 and S2 motors, just enough space for a pair of 1/8" holes. To make sure the 1st stage booster stays attached long enough to ensure 2nd stage ignition, you don't want the coupler to fit too loosely into the 2nd stage. This is cured with a little 1/4" wide masking tape on the coupler to increase its OD a hair. Sometimes a full wrap is needed, sometimes just a couple pieces a 1/2" long, one on each side. Be sure to burnish the edges with your thumbnail.

The last consideration again concerns motor retention - how to make the 2nd stage separate properly at staging. In this case, an aft motor block won't work since that would require stretching the 2nd stage to make room for it. But you can put a tape ring around the forward end of the 2nd stage motor. This will work just like an aft motor block. All that's required is to cut the 2nd stage motor tube shorter and recess it at the forward end by 1/2-3/4". It worked like a charm on my Comanche. The only drawback to this technique is that it won't work on minimum diameter stages.

In the pic you will also notice a tape ring around the aft end of the 2nd stage motor. This is optional. It's there to keep drag from pulling the 2nd stage booster off the motor during flight. The usual way to do this is to lightly frictio fit the motor into the booster section. But, since the motor extends aft, a tape ring works, too.

http://home.flash.net/~samily/farsides/boosters3b.gif

(Download pdf version of this pic.) (http://home.flash.net/~samily/farsides/boosters2.pdf)

Doug

Daniel Runyon
04-22-2007, 11:48 AM
RE: 1st Stage Booster Engines

I don't yet know how to calculate this kind of thing (I'm actually making myself an engine chart with liftoff weights at this very moment), but I've been wondering how well it would work to cluster the first stage (for myself, I would be looking for the cheapes possible combination, maybe two of something, would two or three B6-0's work?) and having single engines 2nd and 3rd stages.

Also, I'm wondering about relatively low altitude staging rockets... I'd like to do some staging, but wouldn't want to get much more than 1000ft... is that wishful thinking or doable?

Thank you very much for the info you're providing Doug! I've just had the staging section of the Handbook as this mornings bathroom reading!

Daniel Runyon
04-22-2007, 12:20 PM
Sometimes the obvious just scoots on by me... I suppose one D would be about the same cost as a coupla B's!

How well would it work to have a D powered first stage, then a B or C powered second and third?

Doug Sams
04-23-2007, 12:45 PM
Sometimes the obvious just scoots on by me... I suppose one D would be about the same cost as a coupla B's!

How well would it work to have a D powered first stage, then a B or C powered second and third?Well, DW, that's what my post was all about. For a rocket the size of the Farside/X, you need to do something like was done in the Comanche and modify it to use a 24mm motor in the first stage. As well as being about the same price as 2 B's, it's simpler and more straightforward, which is probably more appropriate when just getting into staging.

Alternatively, smaller rockets can get by with lesser first stage motors. For example, I have a 3-stage Midget variant that flies great on an A10-A10-1/2A combo. It has plenty of rod speed. And I think a minimum diameter 18mm 3-stager can be flown using a B6 or C6 in the first stage. The Microsonde III (http://www.ninfinger.org/~sven/rockets/nostalgia/74avi06.html) is one example of that. It will need to be built light, and use a long rod, but it can work.

OTOH, the Farsides and Comanche are heavy enough to need some help. The D12 and C11 boosters work well for that.

Your idea of clustering a booster is not without merit, but, as you noted, not really needed here. I've used is on several rockets now, but they're much larger than the Farside. Here's an earlier thread on the subject. http://forums.rocketshoppe.com/showthread.php?p=17764#post17764


Doug

Daniel Runyon
04-23-2007, 01:14 PM
Ahhh... good deal. Read that and the other thread and am soaking it all in. I was afraid that the momentum from the D in the first stage might overpower the initial thrust of the B or C in the next stage, causing some form of problem, but apparently they work just fine together.

To start with, I might do a downscale to work on little A-T's or something. I'd like to be able to fly it in my little (about 1500x600 foot) field!

Sort of a seperate topic, but tied in pretty directly in my case, how large of a rocket can you go and still use a streamer? I'm thinking that if I start playing with staging in my field it might be a good idea to bring em on down without chute float! Sorry to go so basic on you, but I'm just beginning to get all this stuff figured out and tying it all in together as I go!

EDIT:

Well dangit... no more A*-0's!

Doug Sams
04-23-2007, 02:20 PM
Well dangit... no more A*-0's!Not completely. There's still stock out there, and you can fly them at NAR launches under the OOP motor program.

http://www.launchpad2000.com/modrocen-miniengines1.html

Doug

barone
04-23-2007, 02:25 PM
.....Well dangit... no more A*-0's!

Can still be had if you want them bad emough.....

http://www.friendshobby.com/html/Sales/PageE2.htm
http://www.actionhobby.ca/catalog/results.asp?Category=OTH

Daniel Runyon
04-23-2007, 10:14 PM
Yep, once you're paying OOP prices, you may as well just get the B's! I just disovered you can still get Quest B6-0 as standalones (not in a bulk pack like Estes) at reasonable prices.

So what about recovering these high fliers... is it possible to use streamers from that high up and at, say, BT-50, 55 and 60 sized rockets at all?

barone
04-24-2007, 07:15 AM
Yep, once you're paying OOP prices, you may as well just get the B's! I just disovered you can still get Quest B6-0 as standalones (not in a bulk pack like Estes) at reasonable prices.

So what about recovering these high fliers... is it possible to use streamers from that high up and at, say, BT-50, 55 and 60 sized rockets at all?Sure, you can recover just about anyting on a streamer. The Goblin is BT-55, D powered, streamer recovery. Just gotta watch the weight and streamlining. Too heavy a rocket won't land too softly. However, if you're talking upper stages on multiple staged rockets, chances are you don't need to worry about the weight ;).

Daniel Runyon
04-25-2007, 02:20 AM
Doug, I've been studying your drawing here for awhile, I'm now trying to figure out the couplings of the stages. Would you mind posting some images of actual rockets with the stages taken apart, and showing inside both the bottoms of upper stages and the tops of lower ones? No hurry at all, I've still got a lot of figuring out to do before I start building, so whenever you get a little feelin froggy time would be awesome, and if you just dont feel like it that's totally understandable!

Thanks a TON for the info above... it's takin awhile to sink in, but it's good stuff!

Daniel Runyon
05-09-2007, 10:57 PM
I've been looking over the plans for several staged rockets and it looks like they all have tumble recovery on the boosters... evidently that tends to work out pretty good? Is there any way to work in a streamer for the boosters without it getting roasted or getting in the way of igniting the next stage?

CPMcGraw
05-09-2007, 11:23 PM
I've been looking over the plans for several staged rockets and it looks like they all have tumble recovery on the boosters... evidently that tends to work out pretty good? Is there any way to work in a streamer for the boosters without it getting roasted or getting in the way of igniting the next stage?

For most of our small rockets, it would be difficult. Larger, HPR boosters would certainly use some sort of recovery system, and probably electronics to deploy them. In small boosters like what we're working with, tumble recovery is simple and efficient. The boosters are light enough that their impact velocity isn't enough to do damage.

Centuri tried a novel approach with the Black Widow design, incorporating glide recovery in the booster. Note how it didn't catch on for later designs.

There's just not enough room in the front end of a booster to fulfill both requirements -- storage of the streamer, and some sort of protective liner to keep the blow-by and thrust burn from melting the streamer. I suppose one could build a longer booster with a long motor tube to produce a "pocket" for the streamer, but then you still need some method to deploy the streamer out of that pocket without altering the course of the sustainer above it.

It's an academic challenge, but not a practical thing for most models. Simplicity here is the key to success. The streamer would add extra weight in the wrong place -- at the rear -- and it would reduce the performance of the stack overall. It would take additional support to deploy, meaning extra weight, and extra prep time.

Not impossible, just impractical...

Daniel Runyon
05-09-2007, 11:33 PM
In small boosters like what we're working with, tumble recovery is simple and efficient. The boosters are light enough that their impact velocity isn't enough to do damage.

Well there ya go... no more brain shall be wasted on that! Much appreciated!

barone
05-10-2007, 07:29 AM
I've been looking over the plans for several staged rockets and it looks like they all have tumble recovery on the boosters... evidently that tends to work out pretty good? Is there any way to work in a streamer for the boosters without it getting roasted or getting in the way of igniting the next stage?Well, there is a way but it's a closely guarded trade secret. I'll tell you if you promise not to tell anyone else.

It can't be done on minimum diameter models. But on models where you have space between the motor tube and the body tube.....

When you build the sustainer, move the aft most centering ring as far forward as practical. Attach a kevlar shock cord to the booster in such a way that it doesn't interfere with mating the booster to the sustainer (doesn't have to be very long....you're just using it to attach the streamer to the booster). Attach your streamer to the other end of the kevlar. Fold the streamer and insert it in the area between the sustainer motor tube and body tube. When the booster is blown off the sustainer, it should pull the streamer out of the sustainer. I've actually seen this method used. It works. But remember......it's our secret.

Doug Sams
05-16-2007, 12:26 AM
Doug, I've been studying your drawing here for awhile, I'm now trying to figure out the couplings of the stages. Would you mind posting some images of actual rockets with the stages taken apart, and showing inside both the bottoms of upper stages and the tops of lower ones?!Here's some pics I've put together. Let me know what you think. Tell me if something is missing - I've still not glued the MMTs in so I can still take more pics.

http://home.flash.net/~samily/farsides/Farside-XX.html

Doug

Daniel Runyon
05-16-2007, 12:45 AM
Thank ya sir... that writeup and pics does the tricks! Once you get the motor mounts installed I would love to see inside the booster from the top and inside the sustainer from the bottom, if'n ya don't mind, and, as completed units, partially joined from a side view would be awesome too.

Gracias,
Jose Jimenez

Doug Sams
05-16-2007, 10:42 PM
Thank ya sir... that writeup and pics does the tricks! Once you get the motor mounts installed I would love to see inside the booster from the top and inside the sustainer from the bottom, if'n ya don't mind, and, as completed units, partially joined from a side view would be awesome too.Here ya go. Top:
http://home.flash.net/~samily/farsides/s1-s2-top-p.jpg


Bottom:
http://home.flash.net/~samily/farsides/butts-p.jpg


Side:
http://home.flash.net/~samily/farsides/side-p.jpg



Doug

Daniel Runyon
05-16-2007, 10:57 PM
Thanks SO friggin much, Doug... those have made it all quite clear! This whole internet thing sure does make a difference for those of us who are in the boonies and can't just scoot on down to the next club launch and see something like this up close and personal... I really do appreciate your taking the time and touble good sir.

Doug Sams
07-30-2008, 10:29 PM
I finally got the last bit of red paint applied this week and the black stripes on the faux payload section. Voila!
http://home.flash.net/~samily/farsides/comp2-2p.jpg

The payload section is intentionally extra long. It's also fake. My experience with several of the payload birds is that there's scarce room for the recovery system. I also find that large payload sections can cause lots of flex. So I opted to fuse it to the airframe and use noseblow recovery. I stretched the payload section to make sure there was plenty of room for wadding, chute and shockcord.

The launch lugs are mounted on the faux payload section and on one fin. No standoff was used.

No paint other than yellow was used on the fins. Black, white, checked and chrome trimkote was used instead. That sure saves a lot of masking and sanding and masking and painting. In the right two pics, you can see reflections in the chrome.

The nosecone is a BMS BNC-60L with some FNF added to give it a bit of a point as some of the early catalog pics appear to have (although I went a tad overboard and got it a little too pointy).

In the far right shot, you can see one of the vent holes in the first stage booster.

Now we just need some rain so the burn ban is lifted, and I'll give this bad boy a ride!

Doug

.

dwmzmm
07-30-2008, 11:34 PM
Looks really nice! I still have (in-the-bag) the original Astron Farside I've been wanting to
build. Now that we got a nice, large launch site, I may make it one of my build project this
Fall.

moonzero2
07-30-2008, 11:45 PM
Looks AWESOME!

The trimkote you used is it the self adhesive stuff of the iron on?

Doug Sams
07-31-2008, 05:52 AM
Looks AWESOME!

The trimkote you used is it the self adhesive stuff of the iron on?Thanls. It's the peel and stick kind.

Doug

.

samb
07-31-2008, 12:43 PM
Boy that looks good ! I'll bet it scoots too ! I bought a couple of packs of A10-0s from Launchpad2000 and am looking for a suitable vehicle right now.

space_bus
07-31-2008, 01:32 PM
Beautiful finish, Doug!

What motor combo are you planning for the first three-stage launch?

Doug Sams
07-31-2008, 01:49 PM
Boy that looks good ! I'll bet it scoots too ! I bought a couple of packs of A10-0s from Launchpad2000 and am looking for a suitable vehicle right now.Sam,

I'm thinking Mini Brute Midget (EST 0840) :D

Seriously, with a 1/2A3-4T, it's a fun flier.

Doug

.

Doug Sams
07-31-2008, 01:57 PM
Beautiful finish, Doug!

What motor combo are you planning for the first three-stage launch?Thanks. I have a stash of a few C11-0's, so that will be the 1st stage motor for smaller fields such as DARS' Frisco, Texas site (now under burn ban :( ). 2nd stage will either be a B6-0 or an A10-0T (adapted to 18mm).

Sustainer can be a variety of motors. My greatest concern is having enough oomph to get the laundry out. With this rocket's large payload section, I suspect medium delays will be about as good as longs (if not better), so there are lots of options. I was thinking B4-4 for the first flight. I need to run some sim's to get a better feel for the best delay before flying it.

...

It's a little amusing that I'd be fretting not having enough ejection woosh given Estes' recent nuclear ejection charges, but as we all know, Murphy is always lurking on the rocket range :)

Doug

.

Doug Sams
07-31-2008, 02:05 PM
Boy that looks good ! I'll bet it scoots too ! I bought a couple of packs of A10-0s from Launchpad2000 and am looking for a suitable vehicle right now.
BTW, a downscale Farside or X might be a fun 3-stager with those motors. The A10-0T has plenty of grunt for little stagers like that.

Doug

.

samb
08-01-2008, 12:29 AM
Sam,

I'm thinking Mini Brute Midget (EST 0840) :D

Seriously, with a 1/2A3-4T, it's a fun flier.

Doug

.


Midgets ! Doh !?!@# (smacks farhead with hand). Great idea Doug, you got any experience cloning one of those? ;)

LeeR
08-03-2008, 10:24 PM
I finally got the last bit of red paint applied this week and the black stripes on the faux payload section. Voila!

[...]

Doug

.

Love the classic paint scheme, and the checkerboard trim. Very retro! I never had a FArside, but I did have an Apogee II. This is a very cool project, and a "must" to add to an already long list of projects.

Maniac BAR
08-04-2008, 01:46 AM
Boy that looks good ! I'll bet it scoots too ! I bought a couple of packs of A10-0s from Launchpad2000 and am looking for a suitable vehicle right now.

Have you considered the Seattle Rocket Works Mirv Gryphen? It is an older design that is easy to clone. Four A10-0 motors in the booster that ignite four seperate sustainers with your choice of 13mm motors. I made one from some plans I got off some site I can't remember at the moment. :o Every once in a while, one shows up on Ebay as well.

Have flown it five times with 100% success on two of the flights. What a hoot! Perfect straight boost to about 100' and the sustainers actually go straight up! If you saw the rocket as seperate parts, you would see why I was amazed when it all worked. All four came down on their streamers no more than 50' apart from each other.

Major crowd pleaser. :p

samb
08-04-2008, 11:04 AM
Have you considered the Seattle Rocket Works Mirv Gryphen? It is an older design that is easy to clone. Four A10-0 motors in the booster that ignite four seperate sustainers with your choice of 13mm motors. I made one from some plans I got off some site I can't remember at the moment. :o Every once in a while, one shows up on Ebay as well.

Have flown it five times with 100% success on two of the flights. What a hoot! Perfect straight boost to about 100' and the sustainers actually go straight up! If you saw the rocket as seperate parts, you would see why I was amazed when it all worked. All four came down on their streamers no more than 50' apart from each other.

Major crowd pleaser. :p

Very interesting ! The plan are right here: http://www.oldrocketplans.com/srw.htm . Talk about a spare parts vehicle. That does look like alot of fun too. We have got to get some mini booster motors back into production.