engines

[spaceshuttle]

here's the deal: i am building a complete scale model spaceshuttle.
for the shuttle's main engines, i plan to use those mini engines for the teeny-tiny rockets that estes makes, and i will use the size "d" or"e" engines for boosters. i plan to set it up like a real shuttle launch by having the tiny engines ignite a few seconds before the big engines, meaning that the shuttle won't leave the pad until the big engines spark. is anything going to blow up or get engulfed in flames?

 

[Rocketmaniac]

First, welcome to the Rocketry Forum!!!!! And I must say you have a cool username!!!!

Now about your project....... I think you are going to run into a few problems. You say you want to light the shuttle's engines before the booster's, I don't think those tiny motors burn for that long. So, I think they will burn out before the boosters are lite. And then there is the question on how will you hold the whole thing on the pad until time for the boosters to be lit?

I think you project is VERY COOL, just don't know if it's possible. I know there are lots of guys here that will have other ideas and options........

 

[GlennW]

Well I don't want to put a damper on your plan, but as a builder and attempted flyer of the Estes kit myself, I don't know about this if you are looking to use that kit and modify it. Or is this completely from scratch? Either way, you are going to have all sorts of balance and stability issues. Getting the orbiter to fly right is dicey even under the best of circumstances, I don't know how much you're going to have to weigh it down to compensate for the engine weight and how it will fly so heavy, not to mention the other issues the previous poster mentioned. On the other hand, if you are some sort of demented genius and you figure out how to make this work, then more power to ya! Btw, George Gassaway built a larger scale (than Estes) version of the shuttle and his orbiter is actually an R/C glider, how cool is that? There is a cool video of him launching & flying it on the web that I've seen.

Good luck to you,
Glenn

 

[JRThro]

Originally posted by spaceshuttle
here's the deal: i am building a complete scale model spaceshuttle.
for the shuttle's main engines, i plan to use those mini engines for the teeny-tiny rockets that estes makes, and i will use the size "d" or"e" engines for boosters. i plan to set it up like a real shuttle launch by having the tiny engines ignite a few seconds before the big engines, meaning that the shuttle won't leave the pad until the big engines spark. is anything going to blow up or get engulfed in flames?

The Estes A3-4T motor would be the longest-burning of the "tiny" Estes motors since it has the lowest average thrust, and it only burns for 1.01 second, according to the NAR motor certification info at https://nar.org/SandT/pdf/Estes/A3T.pdf .

You might have to rethink your plan to ignite the shuttle motors "a few seconds" before the boosters.

Even the Estes D12 and E9 motors only burn for 1.65 seconds and 3.09 seconds, respectively.

 

[powderburner]

We are glad you joined us!

The other comments and warnings that have already been made are true---- it will be a bit tricky to successfully do what you want.
But it could probably be done with a little work and experimentation.

To answer your questions: Will it blow up? Probably not. Estes-type blackpowder motors have a pretty darned good reliability rate if you treat them properly (stored indoors at constant temperature, dry, not dropped onto hard floors or otherwise abused).

Will it be engulfed in flames? Yes and no----you are certainly going to have lots of fire and smoke but I don't think your model will burn up or anything like that.

You need to use the 'search' tab at the top of the TRF pages to check out old threads about clusters. Getting multiple motors to ignite on cue can be troublesome if you don't know what you are doing, or can be more of a science if you take the proper precautions. And there is probably some way to rig an ignition system to fire the shuttle motors a fraction of a second before you fire the booster motors, although I would probably just trigger them all simultaneously.

OK, here is the piling-on section (more possible problems with your idea)
With the motor combo that you have proposed, you are going to have significantly different thrust characteristics during the burn of each motor (whether ignited in sequence or all together). This will impact your vehicle thrust during launch in a major way unless you turn all the motor mounts to line up with the model rocket's center of mass/gravity. Even at that, you're gonna have a handful. If you don't align the thrust vectors with the c.g. you will have a relatively severe risk of having your rocket do a pinwheel at the top of the launch rod if the two big booster motors do not ignite in perfect synchronization. I use the term 'relatively' because the basic configuration of the shuttle stack is short, wide, and the SRBs are quite far outboard-----without some major additional (non-scale) finnage to achieve stability, you would be tempting the rocket gods on every launch. If I am not mistaken, I think even George Gassaway used a single main motor (hidden in the ET) for his model to avoid possible thrust asymmetries.

 

[spaceshuttle]

wow, this is going to be tougher than i thought...
i'm about to look at the some of the post about syncronization right now...
another alternative that i originally planned to do for the actual orbiter's engines was to use the old "water and seltzer" mechanism. wht i planned to do was to have the shuttle's Orbital Maneuvering engines as a water tank, have a small slot to slip the
Alka-Seltzer tablets in, and let the engines bubble away just for show. after the solution has emptied out, i would light the boosters. are flames, water, and seltzer a bad combination?

 

[spaceshuttle]

Originally posted by powderburner
We are glad you joined us!

why thank you! i'm also on on a madtv forum just like this one, and that gave me the idea to find one of these!

 

[spaceshuttle]

Originally posted by JRThro

Even the Estes D12 and E9 motors only burn for 1.65 seconds and 3.09 seconds, respectively.

on average, how high does the e9 fly, if you know?

 

[illini]

Depends on too many factors to give an off-the-cuff estimate. Go search for a program called wrasp which you can download for free and see the factors that impact performance.

 

[Daedalus]

Welcome.

George Gassaway's shuttle used a single composite motor in the external tank. The SRBs separate but do not contain motors at all- even with small motors in there he was concerned about the asymetric thrust issue. He also used mini motors in the orbiter but fired them after ET sep. to simulate an OMS burn.

Judging by his experience and the fact he did not use the SRBs I think you have a very serious challenge on your hands. This is not to discourage you - just to let you know what you are up against.

Check out his site:

https://members.aol.com/narshuttle/shuttlehome.htm

Personally, I would look at starting in a simple(ish) manner. Don't bother with the orbiter, or even the shuttle stack, at all - Not knowing what your past experience is but develop the project in an incremental manner - something like:

1) Basic single motor kits
2) Own designs - learn about stability and thrust to weight ratios
3) Cluster motors near to the center line of the model, again a basic 'normal' style rocket
4) 2 motor cluster with the motors well separated, perhaps so it looks a little like a very streched ET + SRBs
5) Back to single motors but an asymetric model design - now it is getting to be shuttle like but with a single motor in the ET (Estes kit)
6) Add motors to the ET - still having the main thrust come from the ET
7) No motor in the ET - now it is a boilerplate for the shuttle full stack
8) Full scale model.

Before moving on to the next stage make sure you solve all the problems with the current one. I know it is slow but NASA didn't start with the shuttle - they had enough problems flying single motor rockets at first

Personally, and living in the UK, I would use quickmatch for clustering black powder motors. I use this all the time and it is very reliable with motors starting at the same time. I know other modellers who use multiple Estes igniters and have no problems with that. Either way can work well with practice. It seems that US modellers tend to prefer multiple igniters, UK modellers single igniters and fusing.

Anyway you look at it is a big undertaking. Short model, asymetric model, clustering, widely spaced motors ....

On something like this the journey is going to be more interesting than the final goal, and I am sure extremely frustrating with many problems to solve on the way.

Personally I am at about stage 4, but then I am not after building a shuttle - just a conventional model with SRBs. I like interesting projects with plenty of complexity, and certainly a shuttle will give you LOTS of that!!!

Good luck with the project and keep us all posted on how you progress.

 

[JRThro]

spaceshuttle,

Daedelus' post has prompted me to ask this: What's your background and experience in model rocketry? Personally, I've been into it for just under a year and have yet to launch a cluster rocket, although I'm building a 2-motor cluster rocket of my own design right now. (If you can call a simple 3FNC rocket with a BT-60 tube and nose cone a "design".)

But since it's my first cluster, I wanted to do something simple to start with. Two 18 mm Estes motors in a BT-60 body tube is about as simple a cluster as is possible.

 

[spaceshuttle]

i've been flying for about two years now...

 

[spaceshuttle]

Originally posted by spaceshuttle
wow, this is going to be tougher than i thought...
i'm about to look at the some of the post about syncronization right now...
another alternative that i originally planned to do for the actual orbiter's engines was to use the old "water and seltzer" mechanism. wht i planned to do was to have the shuttle's Orbital Maneuvering engines as a water tank, have a small slot to slip the
Alka-Seltzer tablets in, and let the engines bubble away just for show. after the solution has emptied out, i would light the boosters. are flames, water, and seltzer a bad combination?

i don't want any technical difficulties...

 

[GlassfibreMan]

If you just want the shuttle motors for effect Rapier Motors are what you need. They burn for 20 seconds or so but give such a small amount of thrust they probably wouldn't affect the balance at all.

 

[spaceshuttle]

Originally posted by GlassfibreMan
If you just want the shuttle motors for effect Rapier Motors are what you need. They burn for 20 seconds or so but give such a small amount of thrust they probably wouldn't affect the balance at all.

1. how do you light them?
2. do they sell them in america? (probably a dumb question)

 

[spaceshuttle]

i learned from apogee https://www.apogeerockets.com/education/how_engines_work.asp that a fiery-looking ejection charge shoots from the end of the motor. if i place a long burning motor where the main engines go, will that burn the shuttle glider since it's made of posterboard?

another question is: what are some other venders that sell slow burning engines?

 

[spaceshuttle]

*NEW IDEA*

i was going to put water in the external tank (with ventilation hole near the top and rear) and drop a small dry-ice cube in. i planned to let the smoke billow up into a straw connecting the tank to the orbiter so that the smoke can billow through the SSMEs. is this a safety hazard to the rocket flames?

 

[richalex2010]

What are the SSMEs? I don't think that it should be a problem doing that, depending on where it is, but if you build a special launcher for it, you can have a tray of water on the bottom, and put in lots of dry ice to create a ton of steam, for the "scale" looking launch. One alternative is to find a military surplus store, and get some of the smoke canisters, and put that in external fuel tank, and rig something to make it have all sorts of extra smoke. I really don't know how "scale" you want the actual flight to be, but the Estes motors don't really have enough smoke by themselves for a "scale" looking flight profile, so you could use what is mentioned above, or use composite White Lighning motors in the SRBs (which looks much more like what NASA and about every missile-making company uses for solid-fuel rockets/missiles). You could use Blue Thunder motors (or motor) in the Orbiter to simulate the liquid fuel flame that the main engines produce, to give a very realistic flight profile. Again, I don't know how "scale" you want it to be, or how big it will be (The smallest Blue Thunder and White Lighning motors are 18mm). Welcome to the forum

 

[spaceshuttle]

Originally posted by richalex2010
What are the SSMEs? I don't think that it should be a problem doing that, depending on where it is. Welcome to the forum

thanx!
btw, the SSMEs are the Space Shuttle Main Engines located at the bottom of the winged orbiter...

 

[richalex2010]

Since the combustion hammens inside the motor, it won't affect the flames, and, if you think about it, (I think this is true, it may not be) it is frozen hydrogen, which is used a the fuel in the real thing. Have you already started working on the rocket (if yes: POST PICTURES! everyone will bug you about it untill you do, anyways, so post them soon )? Could you post plans?

 

[spaceshuttle]

Originally posted by richalex2010
Have you already started working on the rocket (if yes: POST PICTURES! everyone will bug you about it untill you do, anyways, so post them soon )? Could you post plans?

https://www.rocketryforum.com/showthread.php?s=&threadid=17155

 

[richalex2010]

Cool! Is it just a paper model converted to fly on rocket motors? I'm going to try this with a paper SS1, should be cool. Anyways... Have you made a way to get the dry ice into the ET? I didn't see one, or is this a mock up of the final project?

 

[spaceshuttle]

it's the final one, but the boosters are mockups. the tip top of the external tank is where i will drop the dry ice in.

here are the plans...
https://www.rocketryforum.com/showthread.php?s=&postid=188406#post188406

 

[spaceshuttle]

i can't find it anywhere, but does anyone know the maximum lift-off weight for the estes e-9?

 

[hokkyokusei]

Originally posted by spaceshuttle
i can't find it anywhere, but does anyone know the maximum lift-off weight for the estes e-9?

https://www.estesrockets.com/catalog_2005.pdf

 

[richalex2010]

The NAR and Estes pages would be the only places I can think of. It also may be on the packages of the motors. If you can't find it, email Estes (though you won't get a response 'till Tus), as they should know it (their own motors--if they don't have it, they are a worse company than any of us expected )


EDIT: I typed this before hokkyokusei replied.

 

[spaceshuttle]

max lift-off weight is .94 pounds...
CRAP! my whole shuttle might weigh 3.5 lbs and...but i'm using two e9 motors, and that...still won't be able to lift it, yes?

 

[richalex2010]

Try using some APCP F motors. More expensive, but they are twice as powerful (and look around 5 times better and are around 10 times louder )

 

[cjl]

Originally posted by richalex2010
Since the combustion hammens inside the motor, it won't affect the flames, and, if you think about it, (I think this is true, it may not be) it is frozen hydrogen, which is used a the fuel in the real thing. Have you already started working on the rocket (if yes: POST PICTURES! everyone will bug you about it untill you do, anyways, so post them soon )? Could you post plans?

Sorry, it's really frozen CO2 (Frozen H2 would be FAR too flammable).

 

[richalex2010]

Okay, I just thought that. The CO2 might affect it, but (if you put it up on F motors) it will be moving fast enough that it will stay away from the gas. By the way, the White Lightning propellant is a "scale" propellant, meaning that it would look almost exactly like the real stuff, so you wouldn't need to have the dry ice (unless you want a TON of smoke)