Saturday, October 24, 2009

Thoughts on small composite motors

I know, I have lots of these 'thoughts on...' posts. I guess I just tend to have thoughts on a number of subjects in rocketry. This is somewhat of a filler while I'm on vacation.

While pondering the new Aerotech E20W during a few slow moments in history on Thursday, it occured to me that the E20, while certainly a great new motor, is not what I really wanted. Although it offers a few advantages over the E15, including higher thrust, the new molded case, and the FirstFire Jr. igniters, as well as the Econojet-style 2-motor packaging with a slightly lower price, it's not a huge paradigm shift over the E15. We already had 3 E motors with White Lightning propellant - the 24mm SU E15, the 24mm RMS E18, and the 29mm RMS E16. We didn't really need another 24mm SU motor.

All 6 Aerotech D motors (ignoring the rarely-used 24/20-40 and 32/60-100 cases for RC gliders), are either White Lightning or Blue Thunder. There's only one other propellant in the E size - the 24mm RMS E11J Black Jack, which doesn't even have enough thrust for a lot of models. F motors add the F12J, F22J and F23FJ (Fast Black Jack / Black Max) motors, but the only extra propellant in that range is the F27R Redline Econojet, which unfortunately is neither a 24mm nor reloadable. Only in the G range do we got more Redlines (G71R, G77R, G67R), Mojave Green (G76G, G78G), and Warp Nine (G339N and G69N; both, unfortunately, are 38mm motors), as well as the Cesaroni G69SK Skidmark.

What I would really like to see is some smaller motors with the more interesting propellants. Gary Rosenfield has stated that G motors are as small as they'll likely ever make Mojave Green propellants, and Warp Nine loads require some electronic deployment device as they can't use delay grains and ejection charges. That leaves, mostly, Redlines, which are okay with me, as I love the laser-red flame and loud roar. I'd like to see some smaller Redlines, at very least something like an F30R load for the 29/40-120 hobby case or 24/40 case, but preferrably a 24mm E Redline, either single-use (SU) or for the 24/40 motor case. I'd also like to see a smaller smoky motor; either a Black Jack (J) D load for the 18/20 or 24/40 cases, or even better an E-size Fast Black Jack load.

The ideal, of course, would be an 18mm Redline. All the awesomeness, in a tiny package!

However wonderful these conjectures would be if realized, I am still enormously happy with the variety of composite motors available in small sizes. Just a decade or two ago, the only D and E motors available were clunky blackpowder, and compositie motors were expensive, and mostly limited to white, black, and clear blue formulations. Today, you can buy composite motors from the D10W up through 150mm O motors, in almost a dozen different formulations. Even better, Aerotech has shown their devotion to us mid-power folks by introducing 2 new 24mm motors - the E20W and F32T - in under a year, improving the G80T, and introducing Mojave Green motors including the G76G and G78G. That's worthy of praise.

I hope you enjoyed this random tangent while I'm enjoying some FOOTBALL. I'll be back tomorrow with your regularly scheduled random daily geeky content.

6 comments:

KenKzak said...

The new E20 sounds interesting.
With 24mm molded SU cases coming out, that should stimulate new motor production and possible retirement or reconfiguration of classics like the E15 & E30, which have become too uneconomical by any standard.

The E11J is about the lower limit possible for slow Blackjack due to small nozzle throat size. However,small fast Blackjacks may be a possibility for the future. I don't have any experience with them though.

I have high hopes for future reloads for the new 24/60 case. Along with it's increased length, it is my understanding that it's construction is sturdier too.

Except under the best viewing conditions, the 24mm F39T is difficult to see as blue. Greens are even harder to see well in small sizes. Red, OTOH, has a much better contrast against blue skies, making it easier to appreciate.

The EGE said...

1) I agree with you - the 24mm molded cases could be a big game changer. They can trash the E15 now if they want, as far as I'm concerned, and I'd be great to replace the E30 as well. The E15 and E30 are too expensive. Someone on TRF pointed out, on the other hand, that the E20s are only about a buck fifty more than E18 reloads.

2) You're right - the Blackjacks do have small throats, and the FJs too. They're very hard to get igniters in. Oh well.

3) I like the 24/60 case, but I really wish the closures were compatible with the 24/40, and until there's more loads than the F35W I won't even consider it.

4) I agree - I cannot see green and blue, and Warp Nine, flames except in pictures, whereas red, black, white, and sparkies are pretty obvious.

Sascha Grant said...

18mm RMS Redline would be sweet!

KenKzak said...

I read that TRF thread as well. That price says more FOR the E20 than agains't the E18.

I've been flying reloads since they first came out, and having just blown my 3rd of 4 dead 24/40 cases [one of them succumbed to farm equipment instead] I would rather see it brought uo to 24/60 standards, or be able to adapt the older loads to the new case.
Yes, I'm waiting for at least one more load before I buy a 24/60 case.

The EGE said...

Farm equipment that destroys motor cases? Remind me not to come near your house anytime soon!

KenKzak said...

Pure dumb luck that a plow disc should catch a reload case that tiny and fold it in half like a beer can. I've seen larger cases done in by plows and harvesters in the past. I also saw a rice harvester damaged trying to ingest an L2 size fiberglass rocket. Farmer was NOT happy.