Never Been Done In Model Rocketry !...(?)

I've decided to embark on an epic project I believe thats never been done in model rocketry. Thats a bold statement for a newbe to the hobby, however I will not be offended for any correction if I'm wrong. On the contrary, I will appreciate any and all input on this project. Actually I would be happy if this was a corroboration of hobbyist.

I want to build a scaled down version of the 1/4 Mercury capsule, use the launch excape system to launch it. I'm not sure of the scale, I plan to print out the parts with the printer set to two images per page, essentially making it half the size of 1/4



I want to use the LES to pull the capsule up then detach pulling out two chutes from the chute canisters, and delpoy a chute from the LES. Basically to do exactly what the whole system was designed to do.



[YOUTUBE]nAeqi44cIpE[/YOUTUBE]

Now we get to the hairy parts. Using one C-6-3 and two C-6-0's ( if there is such a thing) in the LES. I'll need an ejection charge in the LES to deploy the chute I plan to put in, to bring IT down soft. Three ejection charges will deffinantly be way too much.

The next thing will be needed is an ejection charge to blow off the LES and eject the two chute's in the canisters from the top of the capsule. Now, I would like the whole vehicle to be completely dependent on the LES power for flight BUT it may need some boost from the bottom to get every thing up. I figured using LES power would eliminate the need for any stablizing fins and using some sort of boost from the retropack end would probably make them needed.



Another bug will be, if using three engines in the LES and one in the retropack, getting all these timed correctly, to egnite all at once. If the retro boost ejection charge goes before the LES charge I don't think would be a problem, the LES should just continue up untill ejection, it shouldn't be much after the main body charge.

I wasn't sure at first how to attach the LES to the capsule, make it strong enough to pull the capsule up then deatch. So I figured that I could build a body tube through the capsule from the retro pack to the top ( as indicated in the diagram), and make the high gain antenna part of the LES. Then just build a cylinder on the bottom that will incert into the body tube just as a nose cone would.



Building all this will be the easy part, making all these components work together and sucessfully will be the challenge,

I'm not looking for hight, I'm looking for show, I think 80-100' would be plenty.

Yes, C6-0's do exist. They are booster stage motors

closet astronaut said:

I want to build a scaled down version of the 1/4 Mercury capsule, use the launch excape system to launch it. I'm not sure of the scale, I plan to print out the parts with the printer set to two images per page, essentially making it half the size of 1/4.

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I did one of these about a decade ago for NARAM 44 in Texas, but I cheated and put a motor in the base of the capsule. The model flew well, but a bum motor caused an energetic disassembly at ejection. If you pull this off with motors in the prototypical escape motor locations, you will have achieved a significant accomplishment!

The video you attached is of the "Type C" capsule, which Peter Alway covered in his 2002 supplement to "Rockets of the World." Be aware that the Type C capsule and escape tower were very, very different than those used on later Mercury capsules.

https://www.dars.org/gallery/naram44/8/p8080528.htm

James
_______________
James Duffy
[email protected]

You may want to talk to ScottyDog, he and another chap had something very similar a few years back. Let that not deter you from your mission as we all enjoy the adventures of others. You could investigate the use of some pico timers for this project.Go for it!

I say --go for it!--Use all the resources here at the forum. It should definitly challenge your build skills.

The "three ejection charges going off at once" is not quite likely to be the problem you think it is, because delay times are not precise, and it is quite likely the three charges will go off in rapid succession, i.e. rather than "BOOM!!!" you will probably get "bada-boom," and once ejection charge 1 fires, that will probably kick out the laundry, and ejection charges 2 and 3 will basically be firing off into empty air a tenth of a second or so later.

I would guess you might have to work up some kind of burn-string arrangement to secure the LES tower to the front of the capsule nose cone and then cut loose at ejection. However burn strings are usually used to actuate elevons or something similarly lightweight, while the LES tower is going to be carrying most of the weight of the whole vehicle during the thrust phase so that burn string would be carrying a lot of mass. And the thicker you make burn strings to carry more mass, the more likely you may not get clean burn-through.

Another problem is if you want to put motor or motors in the retropack, and then channel the ejection up through the center of the capsule to deploy parachutes for the capsule overall, is that in essence you will be launching two vehicles at the same time: the LES, powered by the 3xC6 motors in the front, and the Mercury capsule, powered by motors in the retropack, and if one of these vehicles starts accelerating a lot faster than the other, the connection points are going to take a lot of stress.

Then to add even a little bit more of complication, you will have to rig up a very complex cluster ignition system to ignite the 3 LES motors and the retropack motors all virtually at the same instant. Even better you are going to have to figure out some way to get the ignition leads to the LES motors OUT of there after ignition -- falling ignition leads with micro-clips, etc etc, coming down as the Mercury capsule starts to lift will almost be begging to get hung up on some part of the overall vehicle.

closet astronaut said:

Now we get to the hairy parts. Using one C-6-3 and two C-6-0's ( if there is such a thing) in the LES. I'll need an ejection charge in the LES to deploy the chute I plan to put in, to bring IT down soft. Three ejection charges will deffinantly be way too much.

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Note that although the C6-0 has no official ejection charge, it does create significant forward pressure as the propellant burns through. This is why staged rockets need to have either a vent in the booster to release this pressure, or have the booster and sustainer motors taped together to prevent the sustainer from being blown off before its motor can ignite. This forward pressure is sufficient to kick out a nose cone and deploy a streamer; I have a couple of parallel staged rockets which rely on it to eject streamers from their boosters!

What this means is that if you do mix C6-0's and a C6-3 in the LES, you'll want to vent the C6-0's to prevent them from deploying its parachute while the rest of the rocket is still on the way up. Another alternative is to use a C6-3 and two C6-5's, then the C6-3 will deploy the parachute and the C6-5 ejection charges will fire after deployment.

SwingWing said:

https://www.rocketryforumarchive.com/showthread.php?t=25121&highlight=escape

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Sooo...it HAS been done, well thats why I used the (?) in the title. I figured with all the rocket geeks here some one had probably done it. I have just never seen any pics or footage of it. This is great, thank you for the link. Mine's not going to be nearly as high tech but these pics have made me reevaluate my construction plans.

Thanks to all who have replied I can see by them I'm SUCH a novice, but you have to start some where.

JSTAR...Yea..deffinanlty alot to take into account.

adrian...the engine setup is deffinanly going to be the challenge, I know nothing about igniting more than one at a time. Seems there's going to be a great learning curve in this project. But.. for right now..ON WITH THE BUILD!

JStarStar said:

The "three ejection charges going off at once" is not quite likely to be the problem you think it is, because delay times are not precise, and it is quite likely the three charges will go off in rapid succession, i.e. rather than "BOOM!!!" you will probably get "bada-boom," and once ejection charge 1 fires, that will probably kick out the laundry, and ejection charges 2 and 3 will basically be firing off into empty air a tenth of a second or so later.

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Problem - I have had this in a cluster rocket. Didn't get over pressurization, but DID get a hole punched through the parachute, which was in the process of deploying, when the second charge went off and pepper-boxed the chute with the cat-litter plug.

Salvage-1 said:

Problem - I have had this in a cluster rocket. Didn't get over pressurization, but DID get a hole punched through the parachute, which was in the process of deploying, when the second charge went off and pepper-boxed the chute with the cat-litter plug.

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Well, you can certainly have a problem if ejection charges go off in rapid sequence (like .005 seconds apart or so) -- the first charge will push the laundry out of the tube and the wadding (dog barf or Estes TP) begins to scatter in the wind, so then Ejection Charge 2 goes off and as you describe, peppers the chute with not only clay-cap fragments, but also hot burning ejection material. So bad things can happen either way.

Yes, it has been done successfully. The video shows a pretty complete history of the project fopr Pad Abort 1 (Gus's model) and Pad Abort 2 (my model).

https://video.search.yahoo.com/vide...+Apollo+Pad+Abort+Project&c=0&sigr=11ap1kqqa&

You know I am going to follow this thread as you may not be the 1st but I look forward to seeing how you do this. I admire your courage in attempting this and with some excellent suggestions from some great rocketeers here I am sure you could do a bang up job.
Cheers
Fred

Gordon, That's a terrific project and your documentary is great!

did make an escape tower jettison for the Neubauer Mercury-Redstone. It only jettisoned the tower and did not pull the capsule away. Also, the tower was not fully scale in that it only used one A-motor to jettison the tower towards the end of the Neubauer Mercury-Redstone flight, whereas the real tower had 3 motors. I flew the Mercury-Redstone in this manner twice, once with a G-motor and once with an H-motor.

sandman said:

Yes, it has been done successfully. The video shows a pretty complete history of the project fopr Pad Abort 1 (Gus's model) and Pad Abort 2 (my model).

https://video.search.yahoo.com/vide...+Apollo+Pad+Abort+Project&c=0&sigr=11ap1kqqa&

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Yea, this is the video I was thinking about when I saw this thread.

Some really great replies and information here. VERY useful. As I have seen though...none of these here do what I have in mind. My goal is to have the LES eject from the capule using it's own chute for recovery, and the capsule to deploy it's own chute and land separate from the tower. Right now I see only two major hurdles. #1 The biggest is ejection of the LES from the capsule. #2 Making the connection of the LES to the capsule secure enough to hold together and pull it up with out just pulling off at launch.

I have started on the main body of the capsule but I think it's too small, the Les is going to be too small for 18mm engines. At this current size I would have to use the engines for the really small rockets. I'm going to finnish this part of the main body to at least get a good idea of the size of all the parts. I may just keep it at it's current scale and go with what I have but that remains to bee seen. Should have some pics up tomorrow.

One really great thing I've seen in the builds is that these capsules all have been completly launched solely on the three tower engines and show stable flight. The one video of the launch using the 18mm was quite under powered, however these were all built using wood, fiberglass and quite complex construction and heavy materials. I'm not even going to come close to the complexity. I'm going solely on a paper model design and sweet simplicity.

Again thanks to all for the input, it's greatly appreciated.

It would be cool to have a Saturn V that is multistage with the top stage would be a clustered LES.

The problem I foresee with this project is that the chute canisters are angled down. How do you plan to keep the chutes in place? Or did I just completely miss something?

cwbullet said:

It would be cool to have a Saturn V that is multistage with the top stage would be a clustered LES.

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It's ironic you bring up this idea, the next project I have on the slate is a 1/48 scale third stage Sat-V flying model.

MasonH said:

The problem I foresee with this project is that the chute canisters are angled down. How do you plan to keep the chutes in place? Or did I just completely miss something?

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I don't know of anything containing the chutes that would point down. The LES chute would eject from the top, and the capsule chutes woud eject from the standard place in the top of the capsule.

Here's the print out of the main body.

I've got the lower part of the main body together, however I think it's going to be way too small. I think I'm going to have to do some manipulation with photo shop of the original files to get to the scale I'm looking for.

This one is 8 1/4" at the base, this ( I'm guessing) would put the LES main at about 1-1 1/2" in diameter.

Looks like I'm starting over.

closet astronaut said:

I've got the lower part of the main body together, however I think it's going to be way too small. I think I'm going to have to do some manipulation with photo shop of the original files to get to the scale I'm looking for.

This one is 8 1/4" at the base, this ( I'm guessing) would put the LES main at about 1-1 1/2" in diameter.

Looks like I'm starting over.

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I would insider that piece alone to be a major, multi-day undertaking, which would probably drive me partially insane! :surprised:
How much do you think this thing is going to weigh? With three C engines, you've only got 12oz of liftoff weight.

closet astronaut said:

Some really great replies and information here. VERY useful. As I have seen though...none of these here do what I have in mind. My goal is to have the LES eject from the capule using it's own chute for recovery, and the capsule to deploy it's own chute and land separate from the tower. Right now I see only two major hurdles. #1 The biggest is ejection of the LES from the capsule. #2 Making the connection of the LES to the capsule secure enough to hold together and pull it up with out just pulling off at launch.

I have started on the main body of the capsule but I think it's too small, the Les is going to be too small for 18mm engines. At this current size I would have to use the engines for the really small rockets. I'm going to finnish this part of the main body to at least get a good idea of the size of all the parts. I may just keep it at it's current scale and go with what I have but that remains to bee seen. Should have some pics up tomorrow.

One really great thing I've seen in the builds is that these capsules all have been completly launched solely on the three tower engines and show stable flight. The one video of the launch using the 18mm was quite under powered, however these were all built using wood, fiberglass and quite complex construction and heavy materials. I'm not even going to come close to the complexity. I'm going solely on a paper model design and sweet simplicity.

Again thanks to all for the input, it's greatly appreciated.

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Stability is helped in the case of a rocket like this by two things: 1) the motors being near the front of the vehicle, in this case, in the LES tower, which puts their weight and the majority of the mass, especially in a paper model, well forward, which puts the CG forward where you want it. 2) The cone shape of the capsule which creates "cone stability" by virtue of the fact that a cone shape automatically has the CP at the 2/3 chord line (2/3 of the length of the cone from tip to base). That's why "finless" rockets like the old Centuri "Spike" and near-finless rockets like the Centuri "Vulcan", the Quest HL-20 lifting body kit, and various "pyramid" shaped rockets by a variety of manufacturers are stable (as well as "spool" type rockets which operate on the same principle aerodynamically). The cone shape itself shifts the CP aft and acts as a single, large fin of sorts. It gets a little more complex when you add on the additional aero-effects of the tower and LES motor canister itself (housing your three model rocket motors) but so long as you keep the CG forward of the CP by a sufficient amount it should fly stably...

As for separation gear, one COULD use a burn string to hold a spring-loaded latch of some sort... a bit of basswood carved into a latch shape and pulled open by a rubber band acting as the spring, with the latch held closed holding the tower to the capsule by the burn string. That way the burn string only has to hold back the force of the rubber band, the structural force and gee loads of holding the two sections together is done by the latch mechanism itself. This is where some inventive engineering comes into play...

Later and good luck with your project! OL JR

closet astronaut said:

This one is 8 1/4" at the base, this ( I'm guessing) would put the LES main at about 1-1 1/2" in diameter.

Looks like I'm starting over.

Click to expand...

Here are some scale references that should be helpful for your project. A couple of interesting things to note about this particular Beach Abort round:

* This was the first use of a production-representative capsule, and was finished in natural metal with a high-visibility orange stripe.
* Like other early Mercury capsules, this round lacked the large pilot's window and had in that location a small porthole.
* This was the only Beach Abort flight of a production-representative capsule, as earlier Beach Abort flights used two different versions of prototype capsules.

James

luke strawwalker said:

Stability is helped in the case of a rocket like this by two things: 1) the motors being near the front of the vehicle, in this case, in the LES tower, which puts their weight and the majority of the mass, especially in a paper model, well forward, which puts the CG forward where you want it. 2) The cone shape of the capsule which creates "cone stability" by virtue of the fact that a cone shape automatically has the CP at the 2/3 chord line (2/3 of the length of the cone from tip to base). That's why "finless" rockets like the old Centuri "Spike" and near-finless rockets like the Centuri "Vulcan", the Quest HL-20 lifting body kit, and various "pyramid" shaped rockets by a variety of manufacturers are stable (as well as "spool" type rockets which operate on the same principle aerodynamically). The cone shape itself shifts the CP aft and acts as a single, large fin of sorts. It gets a little more complex when you add on the additional aero-effects of the tower and LES motor canister itself (housing your three model rocket motors) but so long as you keep the CG forward of the CP by a sufficient amount it should fly stably...

As for separation gear, one COULD use a burn string to hold a spring-loaded latch of some sort... a bit of basswood carved into a latch shape and pulled open by a rubber band acting as the spring, with the latch held closed holding the tower to the capsule by the burn string. That way the burn string only has to hold back the force of the rubber band, the structural force and gee loads of holding the two sections together is done by the latch mechanism itself. This is where some inventive engineering comes into play...

Later and good luck with your project! OL JR

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Thanks Luke I konw I can cout on you'r vast rocketry knowledge. I learned this from you'r replies on PM, you were the insperation for the Atlas rebuild. My only problem is I have to read and reread you'r replies to get my brain wrapped around all the info.

James Duffy said:

Here are some scale references that should be helpful for your project. A couple of interesting things to note about this particular Beach Abort round:

* This was the first use of a production-representative capsule, and was finished in natural metal with a high-visibility orange stripe.
* Like other early Mercury capsules, this round lacked the large pilot's window and had in that location a small porthole.
* This was the only Beach Abort flight of a production-representative capsule, as earlier Beach Abort flights used two different versions of prototype capsules.

James

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James

Great pics. I actually have the whole declassified Merc capsule design manual. There is incredible info in it. Every detail of every system and component of the capsule inside and out.

I will be starting on the maid body again today. I'm having to print off every thing at a 30% reduction through photo shop. That percentage looks like it's going to be about right.


Rocketbuilder
In response to post 23. This part of the construction in the pics is about four to five hours of work. As far as the weight , I won't know that untill I get it together and weigh it. There's so many parts, I'd have to print and cut out every thing then weigh it all. I have to make the shingles for this thing...AGAIN. There's 1,300 dimples (if I rember correctly) to cut out, on the 1/4 it was tedious enough, I can't emagine what it's going to be like at a smaller scale. Here of some pics of the first shingle build.

1300 dimples to cut out?! :y: Why do you do this to yourself?
Sometimes you just have to sacrifice detail for practicality. Trust me, it's worth your sanity.

As you probably know there is the Atomic City plastic 1/12 scale (I think that is about 6" on the base) plastic model. It is heavier than paper, but provide scale data or might serve as a back-up.

closet astronaut said:

I don't know of anything containing the chutes that would point down. The LES chute would eject from the top, and the capsule chutes woud eject from the standard place in the top of the capsule.

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Thats why I added the "or did I just completely miss something?" part :grin: