The Prontosaurus is reimagined

[boatgeek]

Thanks for your suggestion. I'm thinking about it.

So far in my brief life of born again rocketry - under a year - I've used only Estes motors. I have wanted to continue doing that unless the need is compelling. My basic goal has been to build inexpensive rockets that attempt/fulfill a mission or purpose within a set of constraints. Right now my goal is build large, loud and smokey rockets suitable for a small, conveniently nearby field. Do these composite motors fit in my 24mm mount/clip? Are they as loud and smokey as an Estes motor? Is their ejection charge the same, or stronger/weaker, than an Estes motor? If I have built a rocket that must have an expensive composite motor in order to function correctly, I may decide to simply discard the model and build another which corrects the defect(s).

TL;DR: The motors should fit in your clips, and composites make more smoke and noise that black powder.

I believe that the Q-Jet 24mm motors, the Aerotech 24mm SU, and the Aerotech 24/40 reload case fit where a D12 does. That's part of their design brief to make it easier for people like you. Most reloads make pretty decent amount of smoke, with blue motors being the exception. The Black Max motors make lots of dark smoke with not much flame, and the White Lightning motors make a moderate amount of white smoke with a white flame. Noise is generally proportional to the average thrust, so an E26 will be roughly twice as loud as a D12. Composites have a different character to their exhaust noise too, more of a roar and less of a hiss.

 

[neil_w]

Not one but *two* fabulous disclaimers for this one:
1) You do the hobby the way you want, regardless of what anyone else says
2) I fly Estes motors at probably 80%-90% of the time because they suit my needs well in most instances.

That said:

So far in my brief life of born again rocketry - under a year - I've used only Estes motors. I have wanted to continue doing that unless the need is compelling.

I don't understand the reasoning for arbitrarily limiting yourself this way. Composite motors offer very different thrust curves than BP motors that open up new possibilities. Why avoid them?

Let's go through this point by point:

Do these composite motors fit in my 24mm mount/clip?

Yes, no changes required.

Are they as loud and smokey as an Estes motor?

I don't know if I've ever heard anyone complain that a composite motor was less exciting than a BP motor. But ultimately there is exactly one way to answer this particular question, and I think you can guess what it is.

Is their ejection charge the same, or stronger/weaker, than an Estes motor?

They are designed to fly in the same rockets. I have never done any specific mods to accommodate composites, with one possible exception (discussed below). To be fair, ejection charge is always a bit variable, and is something evaluate when you use them.

If I have built a rocket that must have an expensive composite motor in order to function correctly, I may decide to simply discard the model and build another which corrects the defect(s).

Define "expensive". Estes E12s at maximum discount (i.e. ACSupply) are about $5 a piece. Q-jet E26 are $7.50 each from Sirius. A bit more expensive? Yes. Break-the-bank-don't-ever-use-them expensive? Not from where I stand. The Aerotech E20 and E30 cost a bit more, but if you need the higher total impulse (or in the case of the E30, thrust) then you get what you pay for. The E20 is one of my favorite motors, for sure, although I don't get to fly it very often.

The 18mm Q-jet D16 ($5 each at Sirius) is great for 18mm models that need a bit more umph than you can get with BP motors, and I've also used them in 24mm models with adapter when I want less altitude than a D12.

The one exception I mentioned regarding "build to accommodate composites" is that they are usually, at least in the single-use varieties, somewhat higher thrust than BP motors. That's great for getting heavy rockets moving off the rod, but in many cases this will also subject the model to higher G-forces, so your builds must be sufficiently sturdy. My eyes were opened to this when I recently saw @rklapp 's in-flight video of a Super Mars Snooper flying on a Q-jet (D22 or E26, don't remember which), and seeing the fins flex at the initial boost. I haven't yet made any special accommodations for this, but I do tend to overbuild a bit to begin with, and thus far I haven't had any issues. But I haven't flown an E30 yet (I have some but the opportunity hasn't arisen). It is just something to keep in mind.

Simulating the rockets, either with OpenRocket or just using thrustcurve.org, will give you an idea of the rod speed and G forces you'll be experiencing, and will allow you to plan accordingly. Estimating delay time for many of your rockets will be more difficult, because your rockets tend to have unusual features that really go outside the bounds of what the simulators can handle. But you can get a feel for things after a while.

Ultimately, my one real complaint with the 24mm Q-jets and single-use Aerotech motors is that the delays are offered in 4/7/10 seconds, and so many of my rockets seem to want 5 or 6 seconds. But a one second error is not a dealbreaker.

So, bottom line: as disclaimed above, enjoy the hobby the way you want to. But consider taking advantage of the additional options that are out there.

[LOL, @boatgeek covered most of the same ground in about 1/4 the words]

 

[Dotini]

Thanks, guys, I'm getting a real education. I'd be stuffing quarters into the slot at the bottom of the screen if I could find it! It seems as though composite motors might make sense for me at this point.

 

[boatgeek]

Thanks, guys, I'm getting a real education. I'd be stuffing quarters into the slot at the bottom of the screen if I could find it! It seems as though composite motors might make sense for me at this point.

The other benefit that composite E motors have is that they're available by mail order with no hazmat, which means you can shop by price instead of what's close.

 

[Ronz Rocketz]

The E12 motors are great for 3FNC rockets that don't need a lot of speed off the rod. The E26 is great if you're worried the rocket needs more push to keep it in an upward direction. As @neil_w mentioned, the D22 was a bit too much thrust for the SMS. That's an unusual situation with the pods in the fins.

The main caveat I have with the Aerotech motors is that in my experience, the Estes delays are like 1234 and the Aerotech delays are like 1001, 1002, 1003, 1004. I'm not sure if this is considered in the OR optimum delay calculation.

That said, the White Lightening (W) are spectacular, like a blow torch out of the nozzle. The Blue Thunder (T) are okay with an instant flash of blue on the launch plate so not as exciting. I haven't been that impressed with the FJ motors, just more black smoke. They do tend to leave a lot of soot behind on the launcher so use sanding paper or powder afterwards to lubricate and smooth the rod again.

Another point, don't bother using composites at night. BP motors are much more impressive after dark including the minis.

 

[lakeroadster]

Not one but *two* fabulous disclaimers for this one:
1) You do the hobby the way you want, regardless of what anyone else says
2) I fly Estes motors at probably 80%-90% of the time because they suit my needs well in most instances.

That said:

I don't understand the reasoning for arbitrarily limiting yourself this way. Composite motors offer very different thrust curves than BP motors that open up new possibilities. Why avoid them?

Let's go through this point by point:

Yes, no changes required.

I don't know if I've ever heard anyone complain that a composite motor was less exciting than a BP motor. But ultimately there is exactly one way to answer this particular question, and I think you can guess what it is.

They are designed to fly in the same rockets. I have never done any specific mods to accommodate composites, with one possible exception (discussed below). To be fair, ejection charge is always a bit variable, and is something evaluate when you use them.

Define "expensive". Estes E12s at maximum discount (i.e. ACSupply) are about $5 a piece. Q-jet E26 are $7.50 each from Sirius. A bit more expensive? Yes. Break-the-bank-don't-ever-use-them expensive? Not from where I stand. The Aerotech E20 and E30 cost a bit more, but if you need the higher total impulse (or in the case of the E30, thrust) then you get what you pay for. The E20 is one of my favorite motors, for sure, although I don't get to fly it very often.

The 18mm Q-jet D16 ($5 each at Sirius) is great for 18mm models that need a bit more umph than you can get with BP motors, and I've also used them in 24mm models with adapter when I want less altitude than a D12.

The one exception I mentioned regarding "build to accommodate composites" is that they are usually, at least in the single-use varieties, somewhat higher thrust than BP motors. That's great for getting heavy rockets moving off the rod, but in many cases this will also subject the model to higher G-forces, so your builds must be sufficiently sturdy. My eyes were opened to this when I recently saw @rklapp 's in-flight video of a Super Mars Snooper flying on a Q-jet (D22 or E26, don't remember which), and seeing the fins flex at the initial boost. I haven't yet made any special accommodations for this, but I do tend to overbuild a bit to begin with, and thus far I haven't had any issues. But I haven't flown an E30 yet (I have some but the opportunity hasn't arisen). It is just something to keep in mind.

Simulating the rockets, either with OpenRocket or just using thrustcurve.org, will give you an idea of the rod speed and G forces you'll be experiencing, and will allow you to plan accordingly. Estimating delay time for many of your rockets will be more difficult, because your rockets tend to have unusual features that really go outside the bounds of what the simulators can handle. But you can get a feel for things after a while.

Ultimately, my one real complaint with the 24mm Q-jets and single-use Aerotech motors is that the delays are offered in 4/7/10 seconds, and so many of my rockets seem to want 5 or 6 seconds. But a one second error is not a dealbreaker.

So, bottom line: as disclaimed above, enjoy the hobby the way you want to. But consider taking advantage of the additional options that are out there.

[LOL, @boatgeek covered most of the same ground in about 1/4 the words]

The E12 motors are great for 3FNC rockets that don't need a lot of speed off the rod. The E26 is great if you're worried the rocket needs more push to keep it in an upward direction. As @neil_w mentioned, the D22 was a bit too much thrust for the SMS. That's an unusual situation with the pods in the fins.

The main caveat I have with the Aerotech motors is that in my experience, the Estes delays are like 1234 and the Aerotech delays are like 1001, 1002, 1003, 1004. I'm not sure if this is considered in the OR optimum delay calculation.

That said, the White Lightening (W) are spectacular, like a blow torch out of the nozzle. The Blue Thunder (T) are okay with an instant flash of blue on the launch plate so not as exciting. I haven't been that impressed with the FJ motors, just more black smoke. They do tend to leave a lot of soot behind on the launcher so use sanding paper or powder afterwards to lubricate and smooth the rod again.

Another point, don't bother using composites at night. BP motors are much more impressive after dark including the minis.

Thanks for taking the time to post this @neil_w & @rklapp

These should be made into a sticky in the Propulsion Forum. Lot's of data to be gleened from them.

 

[Dotini]

Do the aforementioned composite motors come with their own bespoke igniters? Or do they use Estes igniters?

 

[neil_w]

They come with their own.

 

[Ronz Rocketz]

Do the aforementioned composite motors come with their own bespoke igniters? Or do they use Estes igniters?

The Quest initiators need to be inserted to the front so they are unique. This allows the composites to go faster and louder than BP. There's a skill to inserting the initiator into the composite motors without smashing the tips, so buy extra. I stopped using the shrink tube to secure the initiator and use a bit of masking tape over the end.

I find the 18mm motors can be ignited with a 6v controller. The 24mm motors need 9v like the PSII controller. I'm currently using a 12v battery recharger (if I can remember to bring it with me).

 

[Dotini]

Almost complete Prontosaurus 2 posing with two other models in work. Still needs launch lugs and fluorescent pink paint.


Left to right, clustered D with supersize spin flaps, BT-70/24mm with mini spin tabs, Prontosaurus 2, ready for D or E.

 

[Dotini]

Prontosaurus 2 is 100% ready for flight. I'm not entirely sold on the Krylon fluorescent pink (I can't find the Rustoleum version) and some detail finish rework remains to be done. Construction does continue on the big spinning cluster and Prontosaurus 3.

 

[Hobie1dog]

Thanks for the pictures, interesting thread, I like your rocket stand design. Did you design it?

 

[Dotini]

Thanks for the pictures, interesting thread, I like your rocket stand design. Did you design it?

Thanks for your comment!
I did not design the rocket stand, but it is available from a variety of vendors, including Apogee. I'm not sure who designed it, but it works quite well. However, I did design and build my own launch pad. It folds, packs tightly in my toolbox, and loads and locks 3 sizes of rod.

FYI, I see you are a Hi-Fi addict. I have a nice collection of Doo-Wop and Surf Rock. And I collect everything I can find by the Wrecking Crew.

 

[Hobie1dog]

I like that set-up. I was going to add that I didn't see any big speakers in your workshop, just the small boombox.. Gotta have tunes going while building rockets.

 

[lakeroadster]

Prontosaurus 2 is 100% ready for flight. I'm not entirely sold on the Krylon fluorescent pink (I can't find the Rustoleum version) and some detail finish rework remains to be done. Construction does continue on the big spinning cluster and Prontosaurus 3.

View attachment 496560

Well... that's definitely high visibility! Holy Schnikeys!

 

[BABAR]

Not the most macho of colors, but I like fluorescent pink (and orange) for scratch built rockets, especially “engineering” models where the main goal is to test the validity of a design, in such cases, FINDING the rocket after you launch it is obviously a big plus, and there aren’t to many rocket launching sites that will camouflage a pink rocket. Unpainted balsa, white, black, and green are definitely colors to avoid.

 

[Dotini]

Not the most macho of colors, but I like fluorescent pink (and orange) for scratch built rockets, especially “engineering” models where the main goal is to test the validity of a design, in such cases, FINDING the rocket after you launch it is obviously a big plus, and there aren’t to many rocket launching sites that will camouflage a pink rocket. Unpainted balsa, white, black, and green are definitely colors to avoid.

Do you mean that black or white should not be used as the contrasting color? If we must have a contrasting color to judge spin, what should it ideally be?

Prontosaurus 2 is a relatively big rocket, and even on an E it does not seem likely to go very far, so visibility is not a terribly important quality for this rocket. However, I'm trying to evolve the colors and pattern that is most likely to be seen under more extreme conditions.

 

[jqavins]

While black and white is traditional for roll patterns on "real" rockets, I'm not so sure it's really best. And if your goal is finging the rocket that's on the ground, black and white is surprisingly bad.

I got a set of BT-60 size FARGs from Apogee, which are pretty spindly. I painted one side fluorescent orange and the other side fluorescent pink to be really, really sure I'd find them in the grass. That's also not a great pair, I think, for a roll pattern because they don't contrast with each other as well as, say, fluorescent purple and yellow would. But they each contrast really well with grass, be it bright spring green, dark summer green, yellowed, or brown.

 

[Dotini]

While black and white is traditional for roll patterns on "real" rockets, I'm not so sure it's really best. And if your goal is finging the rocket that's on the ground, black and white is surprisingly bad.

I got a set of BT-60 size FARGs from Apogee, which are pretty spindly. I painted one side fluorescent orange and the other side fluorescent pink to be really, really sure I'd find them in the grass. That's also not a great pair, I think, for a roll pattern because they don't contrast with each other as well as, say, fluorescent purple and yellow would. But they each contrast really well with grass, be it bright spring green, dark summer green, yellowed, or brown.

Fluorescent purple? Fluorescent yellow? Sounds interesting. Available in rattle cans?

 

[jqavins]

Fluorescent purple, yes, if a bit magenta-like. I didn't write "fluorescent yellow", though I'd be very happy to have some, as opposed to regular bright yellow, if it's out there.

 

[BABAR]

Do you mean that black or white should not be used as the contrasting color? If we must have a contrasting color to judge spin, what should it ideally be?

Prontosaurus 2 is a relatively big rocket, and even on an E it does not seem likely to go very far, so visibility is not a terribly important quality for this rocket. However, I'm trying to evolve the colors and pattern that is most likely to be seen under more extreme conditions.

For spin, I’d say you are absolutely right that if you are trying to measure rate of roll, about the only thing that might beat black and white would be black and chrome. But unless you are recording the flight on high speed media, once it starts turning not sure ANY color combo is going to do much.

for RECOVERY purposes, I can think of three situations (There are likely more)

Scale model: where you are limited to the color choice or choices actually used by the vehicle (rocket, Missile, aircraft, spacecraft, whatever) you are mimicking.

Fantasy model: anything goes, whatever makes it look the way you dreamed it up.

Engineering models: rockets designed with unique flight characteristics, example are your Horizontal Spin birds, Helicopters, Gliders, Maple Seed, Cyclone Airbrakers, etc. these may be flown with NO paint (sometimes essential for weight limits), if they ARE painted IMO priorities are ease of recovery (bright colors to make it easy to find), then maybe smooth finish for better altitude, then looks. You are one of those combinations of craftsman and engineer that can make engineering marvels that also look great. I am a 15-20 foot finish guy (at best.). The important thing is that we have fun and are proud of our products. Outside of competition, nothing else matters.

 

[Ronz Rocketz]

Dazzle camouflage is suppose to make it difficult to determine firing range. Of course, radar made it obsolete.

 

[Dotini]

Prontosaurus 2 is ready for launch, and Prontosaurus 3 is almost complete. Pix soon!

I have a few questions, please:

1. Should the shoulders of a balsa nosecone ideally be painted, or not? Once I have a good fit, how will painting it affect the fit? I expect I may have to sand and repaint a time or two.
2. What is the ideal shock cord length for a smoothly finished 31" BT-70 rocket weighing ~10.5 oz and flying on a D12?
3. Should first flight be on a D12-3 or a D12-5?
4. Is the Xform parachute roughly equivalent in rate of descent to a conventional chute of the same nominal diameter? My experience with a few of them so far is yes.

Thanks for any suggestions!

 

[lakeroadster]

Prontosaurus 2 is ready for launch, and Prontosaurus 3 is almost complete. Pix soon!

I have a few questions, please:

1. Should the shoulders of a balsa nosecone ideally be painted, or not? Once I have a good fit, how will painting it affect the fit? I expect I may have to sand and repaint a time or two.
2. What is the ideal shock cord length for a smoothly finished 31" BT-70 rocket weighing ~10.5 oz and flying on a D12?
3. Should first flight be on a D12-3 or a D12-5?
4. Is the Xform parachute roughly equivalent in rate of descent to a conventional chute of the same nominal diameter? My experience with a few of them so far is yes.

Thanks for any suggestions!

1. I typically want the shoulder undersized, so I can use masking tape to get a good fit. Painted or raw.. dealers choice.
2. What is the shock chord made from? Most folks go 2 times the rocket length.. which seems too long to me.
3. I'd go D12-3.. get that laundry out as quickly as possible
4. X-chute, by design, will fall faster than a round chute of equivalent diameter.

 

[Dotini]

1. I typically want the shoulder undersized, so I can use masking tape to get a good fit. Painted or raw.. dealers choice.
2. What is the shock chord made from? Most folks go 2 times the rocket length.. which seems too long to me.
3. I'd go D12-3.. get that laundry out as quickly as possible
4. X-chute, by design, will fall faster than a round chute of equivalent diameter.

Thanks. I like your nose cone solution. I will do that.

I usually make my shock cords at least 4x the length of the model. But I'm considering going longer. I always use Kevlar, rating between 80 and 250 depending on rocket weight.

 

[neil_w]

1. Should the shoulders of a balsa nosecone ideally be painted, or not? Once I have a good fit, how will painting it affect the fit? I expect I may have to sand and repaint a time or two.

Never ever.

2. What is the ideal shock cord length for a smoothly finished 31" BT-70 rocket weighing ~10.5 oz and flying on a D12?

Actually the number that is commonly thrown around on this forum is *3* times the rocket length. Mine are usually in the range of 2x-3x. HPR folks often use incredibly long shock cords, because they're non-elastic and the nose cones are pretty heavy, so there's a lot of energy to dissipate before the cord is fully extended.

My feeling is always that using elastic (vs. just Kevlar) enables you to get away with a shorter cord, but if it's *too* short you can get snap back with the nose hitting the rocket.

 

[BABAR]

1. Should the shoulders of a balsa nosecone ideally be painted, or not? Once I have a good fit, how will painting it affect the fit? I expect I may have to sand and repaint a time or two.
!

ideally the shoulders aren’t seen, so don’t need paint.

if there is a concern (sort of like underwear peeking out on a plumber), if it fits the paint scheme a black sharpie can be used to blacken the shoulder, so depending on your paint a scheme it won’t be as obvious as bare balsa, and doesn’t add to weight or diameter (at least not significantly.)

 

[Dotini]

ideally the shoulders aren’t seen, so don’t need paint.

if there is a concern (sort of like underwear peeking out on a plumber), if it fits the paint scheme a black sharpie can be used to blacken the shoulder, so depending on your paint a scheme it won’t be as obvious as bare balsa, and doesn’t add to weight or diameter (at least not significantly.)

How is your new location working out? Have you found a suitable place to launch?

 

[Dotini]

The Prontosaurus family is filling out. All models are light enough to fly on D12, but E12's will eventually see duty.

From left to right, Prontosaurus 1, 2, and 3. #1 is flight ready. #2 lacks only a dab of paint. #3 is still in the glue, fill, prime and sand stage. All are set to spin and carry ballast in order to limit altitude at a 500' x 500' field.

 

[lakeroadster]

The Prontosaurus family is filling out. All models are light enough to fly on D12, but E12's will eventually see duty.
View attachment 501798
From left to right, Prontosaurus 1, 2, and 3. #1 is flight ready. #2 lacks only a dab of paint. #3 is still in the glue, fill, prime and sand stage. All are set to spin and carry ballast in order to limit altitude at a 500' x 500' field.

Beautiful. Love those bright colors.