RMS Engines?

[CharlieMopps]

Hey there... I'm new to the forum here. I used to do rockets about 15 years ago... gave it up. My girlfriend likes to do crafts with me, so I thought "Why not a rocket?"

So I ordered an Estetes "High Flier" and the site I got it from had a list of engines... Apparently there are these new "Reloadable" engines made by "Aerotech" that would make my rocket go to 6 tenths of a mile! Wow! I'm sure you guys know all about these things but they're new to me.

So I get the rocket and the engines and it appears that there is some sort of engine casing that's not included? I don't get it. Do I need something else? The Engine reloads are 18mm and so is the cardboard engine mount in my rocket. Is this engine casing required? If so, how does it fit in my rocket? The website I ordered from never mentioned a motor casing.

Thanks in advance everyone!

[barone]

Sounds like you just got the reload kit. You need to buy the RMS system which is the casing for the reload. The casing contains the burn so it provides thrust out the nozzle so your rocket doesn't become a flaming mess. They come in different sizes, 18mm, 24mm, 29mm and on up. The 18mm reloads are normally D impulse. If you're planning on using it in your High Flier, need to check and make sure you don't have to add any nose weight to keep it stable.

I don't know where you got the reload from but they probably sell the casing too. You can always check E-Bay and Rocketry On-line (http://rocketryonline.com/) auctions and might be able to pick one up cheaper.

Don
NAR 53455

[ghrocketman]

If you want to use Aerotech reloadable (RMS) engines, then yes a case is required.
They are made in sizes from 18mm all the way up to 98mm (yes, 98mm for M and N motors).
For your rocket you would need the RMS 18-20 (the first number is the case diameter, second number is total possible max impulse for the casing). this casing is around $35.00.
Reloads for this case are fairly limited; there is one White Lightning "D" and one "Blue Thunder" D offered for this case; these reloads are sold 3 per package. In the past, there were loads from B all the way up to a 22 n/sec "baby" E for this case, but unfortunately only the 2 "D" loads remain.
The Aerotech "Hobby" RMS line also includes the 24/40 case (which is the size of an Estes "D" but features loads all the way up to a small 55n-sec "F"), and the 29-40/120 which is 29mm and takes loads up to a 120n-sec "medium size" G engine.
The cases larger than this (longer 29mm cases, all 38mm, all 54mm, all 75mm, and all 98mm) are High Power Rocketry (HPR) cases for H class and above engines and require High Power Certification to fly.
Reloadable engines use different propellant than the common black-powder Estes engines...they use an Ammonium Perchlorate+binder/fuel based propellant that is very similar to the fuel used in the Space Shuttle SRBs.

One thing to keep in mind....the Estes HiFlier WILL go out of sight (over 1500 feet !) on a common Estes C6-7 with the most likely result being loss of the rocket. Use of an Aerotech RMS18 "D" engine (that has OVER twice the power of a C6-7) will ENSURE you lose not only the rocket but also an expensive $35 reloadable engine casing due to the around 3200ft altitude.....a 12" rocket can barely be seen at 1000' let alone 3200' !
The Aerotech RMS18 is great for either heavy for size rockets such as the old Estes Space Shuttle, and also for high frontal drag 18mm rockets such as the Estes Fat Boy.
The RMS18 is best used for rockets that you wished you built with a 24mm "D" size engine mount, but for some reason did not.

[A Fish Named Wallyum]

One thing to keep in mind....the Estes HiFlier WILL go out of sight (over 1500 feet !) on a common Estes C6-7 with the most likely result being loss of the rocket. Use of an Aerotech RMS18 "D" engine (that has OVER twice the power of a C6-7) will ENSURE you lose not only the rocket but also an expensive $35 reloadable engine casing due to the around 3200ft altitude.....a 12" rocket can barely be seen at 1000' let alone 3200' !
The Aerotech RMS18 is great for either heavy for size rockets such as the old Estes Space Shuttle, and also for high frontal drag 18mm rockets such as the Estes Fat Boy.
The RMS18 is best used for rockets that you wished you built with a 24mm "D" size engine mount, but for some reason did not.

And how! Go ahead and sacrifice the Hi Flier on a C6-7. I've helped search for a ton of lost casings over the years, so I can tell you that your chances of finding everything are slim. Go ahead and build the Flier, but leave the engine hook off, put an engine block in and friction fit it with masking tape. It'll at least be a cheap loss.

[CharlieMopps]

Ok, you want me to get a C6-7? I can do that... But why am I removing the hook?

Friction fit the engine mount? Wont it go shooting out the back of the rocket when it deploys the parchute?!?!?

[ghrocketman]

If you want any hopes of getting this one back in anything other than a HUGE flying area with zero wind, I'd reccommend flying first on an A8-3 or A8-5, then maybe a B4-4, B6-4, or B6-6.
Flying it on a C (let alone ANY Aerotech reloadable) most likely will result in loss of the rocket.
Unless your goal is to sacrifice this one to the rocket gods, avoid C engines.
If you just absolutely must use a C engine for machismo reasons or something, replace the parachute with a 6 to 8 foot length Crepe Paper streamer that you tie the shock cord around.
That way, recovery will be within a MILE of the launch pad. :p :p

[A Fish Named Wallyum]

Ok, you want me to get a C6-7? I can do that... But why am I removing the hook?

Friction fit the engine mount? Wont it go shooting out the back of the rocket when it deploys the parchute?!?!?

It's ugly and it will eventually rip down the side of the rocket as a result of the overly enthusiastic Estes ejection charges. My son built a Sizzler back in 2001 and this was its fate. As long as you tape the engine in place securely, it'll hold.

[JRThro]

Ok, you want me to get a C6-7? I can do that... But why am I removing the hook?

Friction fit the engine mount? Wont it go shooting out the back of the rocket when it deploys the parchute?!?!?
Read Bill Eichelberger's reply first, then...

He means you should friction fit the motor into the rocket, not to friction fit the motor mount.

Without knowing ahead of time that this is Bill's preferred way of building Hi-Fliers, I built mine exactly the way he suggests. The motor hangs 1/4" to 1/2" out the back end of the rocket. A single wrap of masking tape around the motor and rocket keeps it in there nicely.

Also, I lost my Hi-Flier by launching it on an Estes C6 motor. This rocket flies really high on both A8 and B6 motors, and irretrievably high (at least in my case) on C6's.

[CPMcGraw]

Ok, you want me to get a C6-7? I can do that... But why am I removing the hook?

Friction fit the engine mount? Wont it go shooting out the back of the rocket when it deploys the parchute?!?!?

Charlie,

That Hi Flier would also fly to about 700' on the even-smaller A3-4T motor. It's a very lightweight design, generally called a "minimal diameter" rocket because the motor mount tube is also the main body tube.

An alternate method of retaining the motor is to wrap masking tape around the motor before inserting it into the tube. That's what "friction fit" means -- there is enough friction between the motor and the tube to prevent the motor from being blown out the back end. Keep in mind that the nose cone and all the laundry -- the streamer or parachute, and the flameproof wadding -- need to freely be able to come out when the motor fires the deployment charge. The idea is, there is more friction holding the motor in place than what holds the nose cone in place. Once the nose cone blows off, the pressure will continue relieving itself in that direction.

The motor hook on that model is completely unnescessary, and should never have been included in the first place. When I built mine, I eliminated it and the mylar ring that slides over it, and carefully cut the fins to fill those gaps. Go back through the Ninfinger archives and look at some of the older designs, like the Laser, the Astro, the Zipper (aka Blue Star), the Sunbird... NONE of those designs used a hook. Friction fit is actually the earliest method of motor retention -- the hook was introduced later, possibly even with the Alpha.

One strong recommendation about the Hi Flier: Don't use the parachute! Change that to a 1" x 10", or 1.5" x 15" streamer instead. A parachute is a guaranteed drift-away in any wind condition other than dead-calm. Also, resist the temptation to use the "C" or even "B" motors. Use the A8-5. A RockSim test shows you can easily reach 600' with this motor, and the deployment speed will be less than 3 FPS (very gentle!).

[CharlieMopps]

It came with a Steamer... not a parachute...

I got a B6-4

4 second delay ok you think?

[ghrocketman]

An A8-5 or A8-3 would be more appropriate for a first flight, but with a streamer, you should be able to get it back when using a B6-4; a B6-6 would probably be closer to optimum delay, but the -4 should cause no problems.
Keep in mind that this rocket will probably fly close to 900'-1000' on a B engine.

[CPMcGraw]

An A8-5 or A8-3 would be more appropriate for a first flight, but with a streamer, you should be able to get it back when using a B6-4; a B6-6 would probably be closer to optimum delay, but the -4 should cause no problems.
Keep in mind that this rocket will probably fly close to 900'-1000' on a B engine.

I just ran a quick RS on the "B" motors...

Using the B4-4 the Hi Flier will reach 1030', but the deployment velocity is over 70 FPS. Even with a streamer you might experience a zipper (or more probably a shock chord break-away) deploying that fast.

Go with the B6-6. You only get 50' more altitude (1080'), but the deployment V is a gentle 6 FPS. You are less likely to have damage to the model with this motor. At 1000', however, the model is going to be nothing more than a tiny black dot against the sky, followed by a thin contrail; if there is an overcast, it might disappear completely from sight until the streamer pops out.

[CPMcGraw]

It came with a Steamer... not a parachute...

I got a B6-4

4 second delay ok you think?

My mistake; you're right about that model coming with a streamer. Many of Estes' models come with a 12" parachute, pre-assembled; this one came with a short streamer. HELPFUL TIP: Run over to Home Depot or Lowes and look for a roll of day-glo "police tape". It's meant to warn people of a wet paint area, or some other danger that they need to be alerted to. This is the same material as the Estes streamer. Get a roll of either the 1" wide or 1.5" wide. Cut the streamer in a 10:1 ratio (a 1" wide streamer should be 10" long; a 1.5" wide streamer should be 15" long...). Personally, I'd go with the 1.5" wide; at 1000' up, you'll need all the help you can get to see it...:D

See my post in reply to ghrocketman. Many of us have the computer program RocSim to work with, and it allows us to "pre-fly" a model in simulation. It really helps to find out what the performance of a new design will be before we actually build it with balsa and tubes. I punched this model into the computer and it indicates that your model will still be moving upward at a very high rate of speed when it pops the streamer, using that 4-second motor. You might loose the model with the nose cone being pulled off. I've had this happen a time or two in my distant past. It's no fun.:(

[CPMcGraw]

I need someone else with RocSim to run a comparison on the Estes Hi Flier model.

I have just run a series of checks for Charlie and his model, and what I'm seeing is a bit uncomfortable. According to my test runs, this model is unstable with any motor larger than the A3-4T (which would still require an adapter to fit correctly). Using the A8-3 and A8-5 motors drop the stability margin to 0.45; the B6-6 drops it down to 0.26!

This comes from the Barrowman computations, BTW. Using RocSim computations produces another set of numbers altogether, but even so, anything larger than an A8-5 produces a less-than-one calibre stability margin.

Can someone else confirm this issue? I'm reasonably sure the model has flown with these other motors, but the real question is how safely? If you guys come up with similar numbers, squawk up here.

[CPMcGraw]

In case anyone is interested in this design, the fin shape is where the problem is found. It's interesting how just altering slightly the fin shape you can get all the stability you need to fly with "C" class motors.

Attached is my correction to the fin shape -- everything else remained the same, minus the engine hook and the mylar ring.

Performance specs:

A8-5......550'......8 FPS
B6-6.....1025'......4 FPS
C6-7.....1790'.....16 FPS

Enjoy!

[CPMcGraw]

Here's another variant of the Hi Flier, this time using the stock fins but lengthening the body tube to the point where RocSim says the model is fully stable, both in Barrowman and RocSim calculations.

Length: 19.835"
Weight: 0.58 oz
Fin Span: 2.733"

A8-5......470'.....17 FPS
B6-6......920'......8 FPS
C6-7.....1660'.....17 FPS

Enjoy!

[snaquin]

I need someone else with RocSim to run a comparison on the Estes Hi Flier model.

I have just run a series of checks for Charlie and his model, and what I'm seeing is a bit uncomfortable. According to my test runs, this model is unstable with any motor larger than the A3-4T (which would still require an adapter to fit correctly). Using the A8-3 and A8-5 motors drop the stability margin to 0.45; the B6-6 drops it down to 0.26!

This comes from the Barrowman computations, BTW. Using RocSim computations produces another set of numbers altogether, but even so, anything larger than an A8-5 produces a less-than-one calibre stability margin.

Can someone else confirm this issue? I'm reasonably sure the model has flown with these other motors, but the real question is how safely? If you guys come up with similar numbers, squawk up here.

Can you post a file for the Estes Hi Flier to run in RockSim. I see the attachment for the "modified plan" but not the original.

Also Charlie if you have a Hobby Lobby store nearby they sell a silver plastic (mylar?) table cloth 84" round for about $2 - $3 with the party supplies that you can cut up to make streamers. I prefer silver because of the reflective nature of this material it can be seen from a very long distance away. I recovered a two stage model rocket that was flown to over 3,000 feet only because I could just barely see the reflection of the sun off the silver streamer.

[CPMcGraw]

Can you post a file for the Estes Hi Flier to run in RockSim. I see the attachment for the "modified plan" but not the original.

Uhhh, sorry 'bout that... Attached below...

Not shown in this file, I just tried adding 3/16 oz of ballast in the NC, and this works well. It brings the margin to 1.19 calibre.


Also Charlie if you have a Hobby Lobby store nearby they sell a silver plastic (mylar?) table cloth 84" round for about $2 - $3 with the party supplies that you can cut up to make streamers. I prefer silver because of the reflective nature of this material it can be seen from a very long distance away. I recovered a two stage model rocket that was flown to over 3,000 feet only because I could just barely see the reflection of the sun off the silver streamer.

I need to look into that, too. Thanks for the tip...

[snaquin]

Uhhh, sorry 'bout that... Attached below...

Not shown in this file, I just tried adding 3/16 oz of ballast in the NC, and this works well. It brings the margin to 1.19 calibre.




I need to look into that, too. Thanks for the tip...

Craig for some reason I came up with even worse looking Barrowman numbers than you :confused:

I came up marginal on the A8-5 real close to what you have, but unstable with the others. My flight on the A8-5 came up within 50 feet of your altitude with exactly the same optimal delay so we must both have very similar launch conditions loaded.

I've come to trust Barrowman with most of my designs but this is very strange considering the Estes recommended B6 and C6 margins that are showing up in RockSim. Craig I think you are correct, it needs that nose weight (or corrected fins) you suggested.

Look what others have said in this review I just found on EMRR

http://www.rocketreviews.com/reviews/kits/est_hiflier.html

I don't think the horizontal flights listed here are all due to the wind. Even the flights listed as calm or 5+ mph wind conditions show less than favorable flights on the larger engines.

Maybe the RockSim calculation method is more accurate than Barrowman in this case and it's just very marginal.

[CPMcGraw]

Craig for some reason I came up with even worse looking Barrowman numbers than you :confused:

You sure did!

I don't think those numbers are coincidental. I think this is a design problem, and one which we can learn from. Fin size is not the all-correcting solution; fin shape has an even greater effect. Now, understanding why is the challenge...

Thanks for the RMRR link. I submitted this information to that site, and now we'll see if any sparks fly...

...probably with more stability than the Hi Flier...:D

[CPMcGraw]

I just found the RKT file that was posted to RMRR (link at the top of the review), and when I loaded the C6-7, it came up with a 0.59 margin using the RocSim calculations. This is not my file, but someone else's (possibly the author of the review...).

We have an unstable model here. If you try to fly it with no ballast, it's an incident waiting for the moment to happen. Estes did not test this design sufficiently before releasing it.

Shoulda tested with RocSim...

[CharlieMopps]

Ok, what do I need to do to be sure my model wont go all wacky and jam my girlfriend in the eye?

Ballast? In the nose cone? How much? Of what kind?

Thanks!

[ghrocketman]

If you place (jam) about .5 ounce of modeling clay up into the nose it would most likely be plenty.

A fin area increase would probably be of benefit also.

[CPMcGraw]

Ok, what do I need to do to be sure my model wont go all wacky and jam my girlfriend in the eye?

Ballast? In the nose cone? How much? Of what kind?

Thanks!

Charlie,

Like ghrocketman said, about a half ounce (or even just a quarter ounce) of modeling clay would work, and would probably be the easiest to stuff into the nose cone, especially if you've already built the model and glued the end cap onto the nose cone. Use a wood dowel, or something like it, to pack the clay as far into the tip as you can.

If you haven't glued the two pieces together yet, you could even use two 1/8th ounce fishing sinkers held in place with epoxy, then glue the end cap onto the nose cone. Does the same thing.

Since you're following this thread, understand that this problem is design-related. Estes goofed on this one by not fully testing the design before shipping the kits. However, as you can also see, it's not impossible to fix the problem. One just has to understand the nature of the problem, and that comes with time and practice.:D

Charlie, do you have a copy of The Handbook Of Model Rocketry, Seventh Edition, by G. Harry Stine (and Bill Stine)? It's a great investment for someone getting started in model rocketry, because it explains what we've touched on in this thread. There is an art and a science to rockets. When you have a grasp of the science, the art develops from it. Give some thought to picking up a copy and reading it. You'll want to keep it handy as you will find yourself going back to it again and again for information.

[JRThro]

Charlie,

Like ghrocketman said, about a half ounce (or even just a quarter ounce) of modeling clay would work, and would probably be the easiest to stuff into the nose cone, especially if you've already built the model and glued the end cap onto the nose cone. Use a wood dowel, or something like it, to pack the clay as far into the tip as you can.

If you haven't glued the two pieces together yet, you could even use two 1/8th ounce fishing sinkers held in place with epoxy, then glue the end cap onto the nose cone. Does the same thing.

Since you're following this thread, understand that this problem is design-related. Estes goofed on this one by not fully testing the design before shipping the kits. However, as you can also see, it's not impossible to fix the problem. One just has to understand the nature of the problem, and that comes with time and practice.:D

Charlie, do you have a copy of The Handbook Of Model Rocketry, Seventh Edition, by G. Harry Stine (and Bill Stine)? It's a great investment for someone getting started in model rocketry, because it explains what we've touched on in this thread. There is an art and a science to rockets. When you have a grasp of the science, the art develops from it. Give some thought to picking up a copy and reading it. You'll want to keep it handy as you will find yourself going back to it again and again for information.
I find myself re-reading parts of The Handbook Of Model Rocketry, Seventh Edition all the time. After I first got into this hobby in mid-2004, I borrowed a copy of the book from the library but soon decided I had to have my own copy, and I'm glad I have it. It covers almost every conceivable topic in model (and some high-power) rocketry, and has made it FAR easier for me to understand many of the posts on this forum and over on TRF (http://www.rocketryforum.com) that presume some knowledge of the topics being discussed.

I cannot recommend that book highly enough.

[CharlieMopps]

Well... I think you guys are over estimating my intrest here... I want to build this rocket, have it shoot up just out of site, and then have it come down so my girlfriend and all her cute little friends can frolick in the field (hopefully in short skirts) looking for it.

I got a 3-pak of engines... and hopefully I can use them all... then place the rocket on a shelf somewhere to remember the day (and the short skirts)

So, buying a book is a bit beyond my plans. I'll try adding some weight to the nose cone. My girlfriend does pottery so maybe I'll use some of her clay.

Thanks guys!

[ghrocketman]

Hmmm....
Seems Charlie has some motives unrelated to rocketry here !
:p :p :p

[snaquin]

Well... I think you guys are over estimating my intrest here... I want to build this rocket, have it shoot up just out of site, and then have it come down so my girlfriend and all her cute little friends can frolick in the field (hopefully in short skirts) looking for it.

I got a 3-pak of engines... and hopefully I can use them all... then place the rocket on a shelf somewhere to remember the day (and the short skirts)

So, buying a book is a bit beyond my plans. I'll try adding some weight to the nose cone. My girlfriend does pottery so maybe I'll use some of her clay.

Thanks guys!

:D

Well we all would like to wish you a most enjoyable day with your rocket (and recovery crew).

.

[JRThro]

Well... I think you guys are over estimating my intrest here... I want to build this rocket, have it shoot up just out of site, and then have it come down so my girlfriend and all her cute little friends can frolick in the field (hopefully in short skirts) looking for it.

I got a 3-pak of engines... and hopefully I can use them all... then place the rocket on a shelf somewhere to remember the day (and the short skirts)

So, buying a book is a bit beyond my plans. I'll try adding some weight to the nose cone. My girlfriend does pottery so maybe I'll use some of her clay.

Thanks guys!Charlie, that sounds like a great plan to me!

You might find that people on this forum and on TRF can be eager to give just a *little* more help than you really asked for. ;)

If you want to be sure to get your Hi-Flier back so your girlfriend and her friends can frolic in the field, an A8 or B6 motor is probably the way to go. And don't forget to use wadding, or you'll melt your parachute or streamer.

Oh, and take pictures! We like pictures here.
;) :) :D

[A Fish Named Wallyum]

Well... I think you guys are over estimating my intrest here... I want to build this rocket, have it shoot up just out of site, and then have it come down so my girlfriend and all her cute little friends can frolick in the field (hopefully in short skirts) looking for it.

I got a 3-pak of engines... and hopefully I can use them all... then place the rocket on a shelf somewhere to remember the day (and the short skirts)

So, buying a book is a bit beyond my plans. I'll try adding some weight to the nose cone. My girlfriend does pottery so maybe I'll use some of her clay.

Thanks guys!
:rolleyes:
It's official. I'm a cynic.

[barone]

Gee, after 30 post........Well, if nothing else, we've learned how to spell Hi Flier and that it's design is unstable for larger engines......

So Charlie....what cha going to do with the re-loads?

Don
NAR 53455

[A Fish Named Wallyum]

I feel like one of the people I crank-called when I was a kid.
"Excuse me, sir, do you have sixteen pound balls?" :rolleyes: ;)

Tell you what, Chuckles. If you don't post the pictures, you're going to have a bunch of middle-aged men VERY..........depressed. :D

[JRThro]

:rolleyes:
It's official. I'm a cynic.
Gosh! Since when?
;)

[JRThro]

I feel like one of the people I crank-called when I was a kid.
"Excuse me, sir, do you have sixteen pound balls?" :rolleyes: ;)

Tell you what, Chuckles. If you don't post the pictures, you're going to have a bunch of middle-aged men VERY..........depressed. :D
Speaking of which, I bet everyone on this forum considers himself either middle-aged or younger. Am I right?

[CharlieMopps]

Gee, after 30 post........Well, if nothing else, we've learned how to spell Hi Flier and that it's design is unstable for larger engines......

So Charlie....what cha going to do with the re-loads?

Don
NAR 53455

I'm not sure, probobly something dangerous.

[CPMcGraw]

I'm not sure, probobly something dangerous.

What could possibly be more dangerous? One boy, several pretty girls, hot rockets, short skirts, open fields...

You're already in highly dangerous territory, Charlie...:D

[CharlieMopps]

When I was a kid I had an extra D engine so I cut some triangles out of Balsa and glued them directly to the motor as "Fins" then glued some piece of plastic that was sort-of cone shaped to the top of the motor as a nose cone.... Stuck a fuse in it and lit it.

Needless to say, it didn't go "up" It went all squirly but generally away from us... until the ejection charge went off... then it came racing back strait twords my head. lol

[ghrocketman]

I'm beginning to sense that Charlie is some sort of wild "outlaw" :D when it comes to rocketry !