18mm cases?

[shreadvector]

The Dixon mini E motors from the 1970's were just over .5 inches in diameter and used a Bates grain. They were long - I think they were about 4 to 6 inches long. They fit into a CMR RB-52 tube which slides over an RB-50 or Estes BT-5 tube. They were an Eforty-something.

Something in 18mm and the length of the AVI gold series motors could have held a full E with composite propellant. Think of the Estes E casing being longer thn the Estes D casing in 24mm diamter. The AVI Gold series motors were black powder and were longer. The new Estes E12 will be very similar to the old AVI E11.8 (they used silly decimal point precision average thrust numbers to make you thik they were super premium motors).

And, the reason it was barely an E, and only available in a short delay, was simple: they simply put a bit more propellant in the space where the longer delay would have gone. I know that they were trying to maintain size compatibility with the 18mm Estes motors, but I would have loved for AT to have come out with a double-long 18mm casing, with a couple of loads for it.

An 18mm full E (or minimal F) would have been freaking COOL! Can you say BT-20 Machbuster?

Hmmmm.... neglecting erosive effects (which you can't in such a long, thin reload, but still), if you increased the nozzle throat to about 1.4 times the original diameter, and simply used two of the grains that would have gone into the D13W or D24T reloads, you'd have roughly an E26W and an E48T.

In reality, to keep erosivity from completely killing you, you'd probably have to at least double the nozzle diameters to keep the Kn under some control. You'd probably also have to switch from a C-slot to a BATES grain geometry, with stepped core diameters (smaller near the top) to keep supersonic flow from tearing the lower grain to pieces. Still, it'd be a cool motor!

 

[accooper]

How was it barely an E? What about the E28 24mm reload or the E30 single use 24mm? What does that make the Estes E9?

Andrew

 

[plano-doug]

How was it barely an E? What about the E28 24mm reload or the E30 single use 24mm? What does that make the Estes E9?

The E27 had something like 22Ns, well short of a full E, 40Ns. It was just a bit more than a full D. I might call it a baby E.

The E28 is spec'd as a full E at 39.7Ns. The E30 comes in at 33.6Ns, a medium-full E.

The Estes E9 is spec'd at 28.5Ns, a low-medium E.

Doug

.

 

[gdjsky01]

I guess I always assumed everyone knew that all impulses are not complete. Many H's are simply just 'a hair' over a full G. And the list goes on. That's why KNOWING the total impulse of what you are flying is (IMO) important.

Getting back to the 18mm... there are plenty of 18mm powered rockets that benefit from a D. And regardless of 'only' two reloads, it's still a D. Again how many different types of 'D's does Estes offer?? Yes, exactly. Aerotech offers 4 times as many if you count 18 and 24mm.

18mm D's are cheap. The cases come up for sale used now and then. Take your LPR stuff to a new level. Or not.

But IMO their a hoot!
:rant: :duck:
:2:

 

[MarkII]

I guess I always assumed everyone knew that all impulses are not complete. Many H's are simply just 'a hair' over a full G. And the list goes on. That's why KNOWING the total impulse of what you are flying is (IMO) important.

Getting back to the 18mm... there are plenty of 18mm powered rockets that benefit from a D. And regardless of 'only' two reloads, it's still a D. Again how many different types of 'D's does Estes offer?? Yes, exactly. Aerotech offers 4 times as many if you count 18 and 24mm.

18mm D's are cheap. The cases come up for sale used now and then. Take your LPR stuff to a new level. Or not.

But IMO their a hoot!
:rant: :duck:
:2:

All of the above, and let's not forget that they are also downright cheap, too. Even the reload casing isn't going to break the bank. Did I mention that they were cheap?

 

[JPVegh]

I guess I always assumed everyone knew that all impulses are not complete. Many H's are simply just 'a hair' over a full G. And the list goes on. That's why KNOWING the total impulse of what you are flying is (IMO) important.

Getting back to the 18mm... there are plenty of 18mm powered rockets that benefit from a D. And regardless of 'only' two reloads, it's still a D. Again how many different types of 'D's does Estes offer?? Yes, exactly. Aerotech offers 4 times as many if you count 18 and 24mm.

18mm D's are cheap. The cases come up for sale used now and then. Take your LPR stuff to a new level. Or not.

But IMO their a hoot!
:rant: :duck:
:2:

Couldn't have said it better. They are a hoot!

 

[qquake2k]

You know, I don't really need an 18mm case. I rarely fly 18mm anything anymore. But I want one. Bad! Simply because I don't have one!

 

[darisd]

Warp 9 endburner?

Seriously? That is asking for trouble. With how thin the case is... it would burn through for sure.

 

[New Ocean]

Seriously? That is asking for trouble. With how thin the case is... it would burn through for sure.

Insulation?

 

[mwtoelle]

There is not much room for an extra-thick liner in that case. The liner is the reason the old E27 reload was available with only a 4 second delay. The old single use E25 was available with 4, 7, and 10 second delays. However, the E25 did not have to contend with the liner with the reload.

 

[New Ocean]

Doesnt warp 9 burn at 1 inch per second? You still only have a 1 or 2 sec. burn max. That doesnt sound hard to insulate. But if it prevents a delay from burning, that would obviously be no good for such a small motor.

 

[JPVegh]

One of the promissed new reloads was to be a D3. There is test video on you tube. I don't know the specifics of the load but one would assume it is a high energy end burner, perhaps blue thunder? Anyway were looking at around 6 seconds of burn for a D3.

 

[New Ocean]

One of the promissed new reloads was to be a D3. There is test video on you tube. I don't know the specifics of the load but one would assume it is a high energy end burner, perhaps blue thunder? Anyway were looking at around 6 seconds of burn for a D3.

Now that is what I am talking about! Love a long burning D... Are there severe insulation problems with that burn time?

Reminds me of the Apogee Medalist motors. I never got around to buying one but they must have been something else. They just cost a ton...

https://www.apogeerockets.com/composite_motors.asp

 

[[POW]Eagle159]

Couldn't they make D and C engines with the different formulas?
Like a Black Jack, Red, Blue, Green, White lightning! for 18mm
I think that would be cool, but I know, Not too many would want that and they would expensive too.

 

[gdjsky01]

Like I said, they are a hoot (IMO).
https://www.rocketryforum.com/showpost.php?p=284460&postcount=4 :grin:

 

[qquake2k]

Like I said, they are a hoot (IMO).
https://www.rocketryforum.com/showpost.php?p=284460&postcount=4 :grin:

I might have to reconsider getting an 18mm case. That looks like fun!