Apogee Medalist Composite Propellant Rocket Motors

[Shade]

I have been looking at maybe purchasing a few of these, in particular the
E6 and F10 versions. I like the idea of the long burn and would like to see
how they perform in some of my rockets.

What are your experiences with them and are they worth the $$$?

TIA,

 

[Wayco]

I put the F-10 in my Apogee aspire and it was like the energizer bunny, it kept going and going and going. All I got back was the nosecone and streamer. That was my first composite motor.

 

[cjl]

They're kind of expensive, and they're fairly limited in what you can put them in due to the low thrust. That having been said, they're amazingly fun. In the right rocket, they give stupendous flights which are incredible to watch. I personally love the E6 in my 24mm big bertha. It just about burns forever. Definitely worth the cost if you have the right rocket.

 

[Zeus-cat]

A guy launched a rocket on an E6 at our last club launch. It took off and just kept going and going. After it flew out of sight I asked him if he was going to look for the rocket. He said he didn't know if it was worth the bother as we really only had a vague idea of which way it went. I don't know if he ever tried to find the rocket.

The RSO later said it was like watching an 8 second C6.

 

[Shade]

Well if I get my wish of an Apogee Saturn V, I was thinking of making it with
a five engine cluster 4 outboard 24mm engine mounts and one central 29mm
mount. Then I could use and adapter for the center mount and launch it on
five E6-4's, I am thinking that would be way cool!!! Expensive but cool! Or
launch on the recommend single G7x-4.

I also have some other rockets that would be excellent choice for the low
but long thrust of these engines.

 

[cjl]

Honestly, I wouldn't try a saturn v on a cluster of e6 motors. There's just too much risk if not all of them light. They are fun motors to be sure, but I would stick with lighter, more stable rockets for them.

 

[Shade]

Honestly, I wouldn't try a saturn v on a cluster of e6 motors. There's just too much risk if not all of them light. They are fun motors to be sure, but I would stick with lighter, more stable rockets for them.

What's the fun in that. The Ap Sat V is fairly light at 17 ozs.

 

[Joe V]

A guy in my club had some, he seemed to have a very difficult time getting them to ignite.

 

[Zeus-cat]

Apogee says that a G53-5 is a very poor choice as the rocket doesn't go very high and delay is too long. Five E6s wil have even less thrust.

The rocket is 5.6 inches in diameter so the aerodynamic drag will probably be much more of a factor than the weight. If you do launch it on five E6s make sure you take a video of it as it will be the rocket's first and last flight.

 

[Shade]

A guy in my club had some, he seemed to have a very difficult time getting them to ignite.

I do plan on testing out ignition on the before stuffing 5 in a Sat V.

 

[cjl]

What's the fun in that. The Ap Sat V is fairly light at 17 ozs.

That's without a cluster mount or the extra nose weight it would need with 5 motors in the back. Also, E6s are not what I would describe as capable heavy-lift motors, and 5 of them would still be questionable on anything more than about 22oz or so (even if you did get all of them lit).

 

[Bazookadale]

Put a high thrust G in the center mount surrounded by E6 motors - yes the ignition would be a PITA.

 

[Zeus-cat]

I gave the drag issue a little more thought. The frontal cross section of a rocket is pi * radius squared. For a one inch diameter rocket that would be pi * 1 * 1, or just pi. For the Saturn V it is pi * 5.6 * 5.6 or roughly pi * 28. So you need to move 28 times as much air out of the way to fly the Saturn V as you do for a typical one inch diameter rocket. Plus, the Saturn V kit has all sorts of details on it that will add even more to the drag.

 

[Shade]

A guy in my club had some, he seemed to have a very difficult time getting them to ignite.

Thanks that is good feedback.

Apogee says that a G53-5 is a very poor choice as the rocket doesn't go very high and delay is too long. Five E6s wil have even less thrust.

Lets look at the numbers.

............Total Impulse.....Max Thrust.....Simmed Alt.....Comments
G53-5FJ.....92 Ns...............84 N..............366'.............Apogee reports poor choice
G79-4W....108 Ns.............93.9 N.............430'.............Best first flight
E6-4 (x5)..200 Ns..............77 N...............TBD.............Goal realistic launch.

I calc the liftoff mass to be 687 grams and the max liftoff mass with
5x E6 motors to be 875 grams. Couple that with the almost double total
impulse I should get some very good altitude, and possibly the E6-6 might
be a better choice with the long burn.

The rocket is 5.6 inches in diameter so the aerodynamic drag will probably be much more of a factor than the weight. If you do launch it on five E6s make sure you take a video of it as it will be the rocket's first and last flight.

Gee thanks for the positive support.

That's without a cluster mount or the extra nose weight it would need with 5 motors in the back. Also, E6s are not what I would describe as capable heavy-lift motors, and 5 of them would still be questionable on anything more than about 22oz or so (even if you did get all of them lit).

First the mass difference is not all that great.
RMS (reload) G79-4W loaded mass is 158 grams (I already own this hardware)
5x E6-4 mass is 205 grams.
There are more ways to adjust Cp and Cg than just by adding nose weight.
I have already consided using clear fins and just gluing on scale size fins for
a more normal appearance.
I have attached the spreadsheet I am using to review mass analysis.

Now for the real challenge how do you light all 5 motors reliably?
Any ideas on how to get it done.

View attachment Saturn V - five engine cluster.xlsx

 

[Shade]

I have been looking at maybe purchasing a few of these, in particular the
E6 and F10 versions. I like the idea of the long burn and would like to see
how they perform in some of my rockets.

What are your experiences with them and are they worth the $$$?

TIA,

And if anyone just wants to comment on their experience or second hand
information on the initial question that would be much appreciated.

 

[Wayco]

I'm probably the least qualified to comment on this with only a few composite motors under my belt, but the first F-10 I used took three tries to ignite. After two copperheads failed to start the motor (even though they lit) I used a first fire jr. and got a good ignition. I have only successfully ignited one F-20-7W with a copperhead, and it seemed to take forever to light it. No experience with clusters, but I'm assuming it would take a BIG battery and multiple clip whips to achieve a good launch with all motors firing.
I get the idea that a real Saturn launch was spectacular because of the massive flame and long duration, but can you really duplicate that with a model?

 

[Shade]

I'm probably the least qualified to comment on this with only a few composite motors under my belt, but the first F-10 I used took three tries to ignite. After two copperheads failed to start the motor (even though they lit) I used a first fire jr. and got a good ignition. I have only successfully ignited one F-20-7W with a copperhead, and it seemed to take forever to light it. No experience with clusters, but I'm assuming it would take a BIG battery and multiple clip whips to achieve a good launch with all motors firing.

My first attempts definitely had a learning curve. And clustering AP motors is
always a challenge, I understand that.

I get the idea that a real Saturn launch was spectacular because of the massive flame and long duration, but can you really duplicate that with a model?

One can try, can't one. The only way not to fail is to stop trying.

 

[The EGE]

Perhaps build a test model, before you risk a fifty-hour rocket? If you did some fabrication of basic parts (i.e, rolled paper cone, etc) then you could make a basic full-scale mockup for no more than 30 or 50 bucks - just enough to make sure that 5 E6s will actually lift the weight.

Also, be a good practice at the 5-motor cluster.

In any case, take video. A cluster like that is either a spectacular success or a spectacular failure. Good luck!

 

[Zeus-cat]

Hey Shade, it isn't that I wasn't being supportive; it was more of a fair warning situation. I would hate to see anyone buy a nearly $300 rocket, put many hours into building it and then see it crash because they thought they could modify it and get it to fly with a unique motor configuration. Personally, I doubt that this is going to work well as I think this will be underpowered. That said, if you really want to do this you know the risks; go for it and take some video. I don't like NASCAR, but I do like to watch the crashes. I hope this doesn't fall into the same category.

I have done some clustering and I have found the performance does not appear to be as good as a single motor. For example, two C6 motors do not seem to deliver the same performance as a single D12. This may happen because the thrust curves of the two motors do not overlay each other precisely. With the five motors you want to use this could be even more problematic. Therefore, your estimate of 77N of peak thrust is almost certainly on the high side.

 

[Shade]

Perhaps build a test model, before you risk a fifty-hour rocket? If you did some fabrication of basic parts (i.e, rolled paper cone, etc) then you could make a basic full-scale mockup for no more than 30 or 50 bucks - just enough to make sure that 5 E6s will actually lift the weight.

Also, be a good practice at the 5-motor cluster.

In any case, take video. A cluster like that is either a spectacular success or a spectacular failure. Good luck!

Thanks for the idea, actually was already thinking of doing that. And started
doing some CAD work on a prototype a few days ago. First priority is finish
all me in progress kits and repairs. Just the basic shape of the Sat V with a
central 29mm and four perf. 24mm.

I am also looking into making my own igniters, very hot ones, for better ignition.

Also have to double check launch rod or rail length for stable flight.

 

[Tronman]

I launched my Big Daddy this past Saturday with an E6-4. After 3 tries with a Quest Q2G2, it finally ignited with a <gasp!> Copperhead. It was a really nice, long flight with that 7 second burn. Is it worth the cost of the motor? Maybe once in a while.

 

[Zeus-cat]

And another thing; five Apogee E6 motors makes this a high power rocket. Actually, four of the E6 motors will do that. Once you exceed 62.5 grams of propellant you are in high power territory and each E6 has 22 grams of propellant.

 

[MarkII]

And another thing; five Apogee E6 motors makes this a high power rocket. Actually, four of the E6 motors will do that. Once you exceed 62.5 grams of propellant you are in high power territory and each E6 has 22 grams of propellant.

Actually, the 62.5 gram limit is for an individual motor. For clusters or staged rockets, I believe the limit is 125 grams (equivalent to 2 x 62.5g). Since five E6 motors have a combined propellant mass of 110 grams, the cluster itself doesn't require high power certification. In terms of installed impulse, a cluster of five E6s has a combined impulse of 189 N-s, well below the 320 N-s limit (for total installed impulse) before HP certification is required.

 

[Zeus-cat]

MarkII,

I got the text below from the NAR website. You could be right as the line makes no distiction on how many motors it is referring to. I interpreted the clause as being for all motors combined as the clause does not make a distinction as it did for the total Newtons (160 for one motor or 320 for multiple). It is not clear from the context if the clause is for each motor or all motors combined.

A rocket exceeds the definition of a model rocket under NFPA 1122 and becomes a High Power rocket under NFPA 1127 if it:

Uses a motor with more than 160 Newton-seconds of total impulse (an"H" motor or larger) or multiple motors that all together exceed 320 Newton-seconds;

Uses a motor with more than 80 Newtons average thrust (see rocket motor coding);
Exceeds 62.5 grams of propellant
Weighs more than 1,500 grams including motor(s); or
Includes any airframe parts of ductile metal.

 

[MarkII]

It is not clear from the context if the clause is for each motor or all motors combined.

On the contrary, the text you quote makes the definition very clear.

"A rocket exceeds the definition of a model rocket under NFPA 1122 and becomes a High Power rocket under NFPA 1127 if it:

Uses a motor with more than 160 Newton-seconds of total impulse (an"H" motor or larger) or multiple motors that all together exceed 320 Newton-seconds;

Uses a motor with more than 80 Newtons average thrust (see rocket motor coding);
Exceeds 62.5 grams of propellant
Weighs more than 1,500 grams including motor(s); or
Includes any airframe parts of ductile metal."

"a motor" is:
- one single motor

"multiple motors" can be either:
- a group of motors that are ignited together in a cluster, or
- a group of motors that are ignited in subgroups, e.g., as in airstarts, or
- motors in different stages of the rocket, or
- any combination of the above.

In the case of "multiple motors," it doesn't matter which one of the four possible meanings is used. The rule applies equally in all of them.

 

[shreadvector]

Is anyone using this anymore:

https://www.doug79.com/stuff/HPR_metric9c.pdf

 

[GregGleason]

Shade, if you haven't already seen this document on clustering, it's pretty helpful:

Flying cluster rockets for fun and profit

Greg

 

[Shade]

Is anyone using this anymore:

https://www.doug79.com/stuff/HPR_metric9c.pdf

Shread, thanks that is an excellent reference, better than my scribbled
notes, and least my notes did make it into my reference binder, as will
that page.

Shade, if you haven't already seen this document on clustering, it's pretty helpful:

Flying cluster rockets for fun and profit

Greg

Greg,

Thanks I will have too read that later, you had some extra in your link, I
fixed in the link I quoted above.

 

[Adrian A]

I'm probably the least qualified to comment on this with only a few composite motors under my belt, but the first F-10 I used took three tries to ignite. After two copperheads failed to start the motor (even though they lit) I used a first fire jr. and got a good ignition. I have only successfully ignited one F-20-7W with a copperhead, and it seemed to take forever to light it. No experience with clusters, but I'm assuming it would take a BIG battery and multiple clip whips to achieve a good launch with all motors firing.
I get the idea that a real Saturn launch was spectacular because of the massive flame and long duration, but can you really duplicate that with a model?

The F10s are tricky to ignite, because it requires the ignitor to lay sideways across the slot in front of the nozzle. Usually, a copperhead can do this better than any other type of ignitor, once you get a feel for how it needs to go, because of its flat strip shape. It is a "feel" thing since the slot it has to go into is invisible behind the nozzle. I used to be about 1 for 5 with a variety of ignitors, but now that I know how to do it, I can get them to light on the first copperhead, pretty much every time.

Oh, and another thing: With about 1 day's build, you can make a cardboard rocket that can crush the current Tripoli world record, if you build light and put a Beeline transmitter next to the required Raven altimeter. The lighter the better, but use big fins. A moderately-optimized rocket can clear 7,000 feet, easy, using an F10.