Staging Methods for LPR Rockets...

[Al_M]

A little off-topic: can you fly a D-powered booster coupled to a B or C sustainer?

 

[neil_w]

A little off-topic: can you fly a D-powered booster coupled to a B or C sustainer?

Yes, no problem. Estes has done it in some kits.

 

[Alan15578]

I agree with the last 2 posts concerning Composites and Delays : Apogee Rockets says basically the same thing on their website. Engine-to-engine staging is pretty much a "Black Powder Thing" and not something Composites are even designed to do since they ignite and burn differently. As far as time-delay motors in the booster, I "think" there even might be a NAR rule against that (at least in Low Power - which is all I do and pretty much all I know about) for safety reasons since any delay invites tilting-before-igniting the 2nd or later stages at least, and possibly reaching apogee first and heading downward before igniting the next stage at worst.

There is no NAR rule against that, that I am aware of. Yes, you do need to know what you are doing. Still, the word of the local RSO is god.

 

[Alan15578]

I haven't heard much about folks using non-zero delay motors to ignite an upper stage. An ejection charge is much more energetic than the burn-through you get from a -0 BP motor, is it really safe and effective? Here, by "safe", I mean "safe for the rocket".

Also, 4 seconds is a pretty long coast between stages of a low-powered rocket. Would need to be very to sim and confirm that the upper stage would light with sufficient velocity, otherwise good chance of cruise-missiling.

It is not and should not be standard practice, but it does have its uses. When done properly it is just as safe as zero delay staging. Delayed staging may be less reliable, but neither is 100%. A staging failure will result in a prang, so you should aim your rocket to land in the center of a clear recovery area, in the event of a staging failure.

If you are not familiar with delayed staging, you should dread the reports of Tom Keuchler in the old NAR Tech Review.

 

[Alan15578]

The other way around (1st stage BP, 2nd stage composite) would require electronically triggered ignition of the composite sustainer motor.

That is not true, although the ideal way would be to have a flight computer electronically ignite the sustainer at the optimal conditions.

Composit propellant motors can be ignited without electricity just like BP to BP motors, when properly prepped. In fact the original Centuri Enerjets were ignited with a wick that burned up the core and stated the motor at the top, The wick was stared on the ground electricaly, but it took a second or two to start the motor. Some folks did not like the brief delay and had the NFPA codes changed to require enginge start within a second. This led the current igniter style were wires are run all the way to the top of the core and then ignite a pyrogen. Some motors even have the pyrogen pre-installed in the motor core. Again, as with BP to BP, electrons are not required for air starts, but composite motors must me properly prepped for ignition.

 

[Sooner Boomer]

I've got a two stage Fat Boy I call "The Lawn Boy" (John Deere livery). It uses a 24mm booster short-gap staged to 18mm. I moved the upper stage motor mount back a bit so that it now sits *inside* the booster motor tube.

 

[BABAR]

If you are not familiar with delayed staging, you should dread the reports of Tom Keuchler in the old NAR Tech Review.

Are they really that bad?

 

[neil_w]

Are they really that bad?

I certainly do dread them.... but I would also like to read them. Are they available anywhere?

 

[Hyak]

This is probably beyond what you want as its not "keeping it simple" but I use (and prefer actually) electronics (timers or Altimeters) to air-start the sustainers.

I have done this down to BT-55 Airframes, and probably could go smaller.
Admittedly I have not done this on a 'straight' kit build, but I would think that it would not be very difficult to make the required mods.

Also I personally use some sort of positive motor retention on everything (no tape), and prefer active separation as opposed to to Drag separation.

I try to use motor-delay ejection to deploy the booster recovery, and sometimes as a secondary or tertiary back-up ejection for sustainers when possible.

Again, I am talking about LPR. (24mm & 29mm) But I could see where it could work on 18mm motors, but keep an eye on total mass.

For straight Kit builds in the13mm & 18mm motor range I have used Tape as described above.

Anyway, my $0.02

 

[dpower]

I have a 2-stage Fat Boy, painted red & green, with Santa's Private Reserve Rogue Ale (mmm, tasty!) decals. Booster and Sustainer are 3x18mm clusters. I call it "Santa's SIx-Pack". It's flown every christmas club launch for at least 10 years. There's about 1" of gap between the motors, and vents in the coupler. It *does* require nose weight. I don't recall it ever failing to light all 3 sustainer motors.

 

[Bruiser]

"can you fly a D-powered booster coupled to a B or C sustainer"

My Tempest build is a 24mm booster gap staged to an 18mm sustainer. Really nice flyer and the staging is great! Cheap to launch too

(2) Two Stage Tempest Build | The Rocketry Forum

-Bob

 

[Alan15578]

I certainly do dread them.... but I would also like to read them. Are they available anywhere?

I'm sorry about the "d". Have you tried NARTS? You also might try old issues of The Model Rocketeer.

 

[James Duffy]

A black powder booster motor has no ejection charge at all.

That's technically true, but a BP booster motor will absolutely deploy a parachute or streamer with violent efficiency. We did it with our FAI Bumper WAC scale altitude models for many years, using both B6-0 and B14-0 motors. It provides (quite literally) a zero second delay immediately after the booster thrust ends.

What the booster stage won't do in that particular application is ignite an upper stage with any reliability. In our case we instead used a "vertical cluster" arrangement, igniting the booster and a thermalize wick hanging out of the back of the sustainer motor. The delayed ignition of the upper stage provided a reasonably realistic simulation of staging.

James

 

[flaperon]

Because I searched "staging" and ended up here so I thought I'd ask...

I'm adding a third stage to one of my Estes Sashas and I'm wondering about stability.

The CG moves aft about the same distance of the length of the booster when the second stage is added. I'm guessing that boosters cannot be added indefinately as soon the airframe will be mostly fins.

I will assume that some area will be added to the nose and I'm thinking of a coupler for a temporary nose extension and perhaps even some extra weight also.

Any tips regarding CG (or anything) are appreciated.

An E12-0/E12-0/E12-6 in a Sasha should be a show.

Thanks.

 

[neil_w]

Because I searched "staging" and ended up here so I thought I'd ask...

I'm adding a third stage to one of my Estes Sashas and I'm wondering about stability.

The CG moves aft about the same distance of the length of the booster when the second stage is added. I'm guessing that boosters cannot be added indefinately as soon the airframe will be mostly fins.

I will assume that some area will be added to the nose and I'm thinking of a coupler for a temporary nose extension and perhaps even some extra weight also.

Any tips regarding CG (or anything) are appreciated.

An E12-0/E12-0/E12-6 in a Sasha should be a show.

Thanks.

Enter it into Rocksim or OpenRocket to evaluate stability.

Also check out speed off the rod.

 

[Art Upton]

I did find the referenced info on the Apogee and Estes websites after I posted my initial question. Obviously for LPR, things really haven't changed at all, and I'll just need to experiment with the fit of everything next time I fly this one. As old as it is, I may just keep it on the shelf and find something more easily replaceable for messing around with 2-stage flight... or better yet, design my own.

Cheers!

An Estes easy 2-stage rocket is the Mongoose. I have many in my stash as sometimes they disappear ! The method is fool proof as long as you use clear tape on taping the two motors together as the booster has the previously mentioned engine block at the bottom.

So you tape the two motors together insert into the top the booster engine tube and the push that engine stick up into the main rocket.

Fire and likely forget using C6-0/C6-7 !!

 

[BEC]

...with the caveat that the Mongoose booster usually streamlines in, so you want to be sure that it's aimed downrange when you fly it.

 

[Art Upton]

A little off-topic: can you fly a D-powered booster coupled to a B or C sustainer?

Many times you can just put a C motor into the top hole of a D12-0 motor. Back in the 70's before a certain person complained about this practice in Competition, we glued the two motors together to gain extra thrust from the empty D motor. I flew a few of those in competition in when it still was allowed. IN Fact the NAR newsletters at the time had articles and MATH on how it worked so well... They also had articles by very famous early 70's competition people on how removing the ejection charge from a B-2 motor allowed delayed staging to extra altitude for competition.

Edit: Just found the old memory cell location for what that was called, "Tandem Motor", if you don't glue it , it is still NFPA legal

 

[Art Upton]

...with the caveat that the Mongoose booster usually streamlines in, so you want to be sure that it's aimed downrange when you fly it.

Yes I have seen that a few times on mine. I always aim staged models down range

 

[boomtube-mk2]

Below is Bumble D, it shouldn't fly but it does. Two stage D-powered the booster is unconventional to say the least. Since it would otherwise come down like a rock, I provided a streamer to both slow its decent as well as making it easier to see on the way down and locate once it lands.




With an overall length of apx.14 inches, about two/thirds of the booster motor resides inside of the sustainer's airframe.

You can easily see the vent hole for use in "Gap-staging".

 

[Ronz Rocketz]

Because I searched "staging" and ended up here so I thought I'd ask...

I'm adding a third stage to one of my Estes Sashas and I'm wondering about stability.

The CG moves aft about the same distance of the length of the booster when the second stage is added. I'm guessing that boosters cannot be added indefinately as soon the airframe will be mostly fins.

I will assume that some area will be added to the nose and I'm thinking of a coupler for a temporary nose extension and perhaps even some extra weight also.

Any tips regarding CG (or anything) are appreciated.

An E12-0/E12-0/E12-6 in a Sasha should be a show.

Thanks.

Definitely add NC weight. The third stage should get the rocket to orbit or maybe to the ISS.

 

[flaperon]

Maybe I can get to Hawaii

 

[boomtube-mk2]

When you add a third stage to a two-stage rocket, is it advantageous to make the fins on the third stage larger than those on the second stage?
Is there a disadvantage to making them smaller?

 

[neil_w]

When you add a third stage to a two-stage rocket, is it advantageous to make the fins on the third stage larger than those on the second stage?
Is there a disadvantage to making them smaller?

It's all about maintaining proper CG/CP relationship. Stages add more weight in the rear, oftentimes larger fins are needed to compensate. Simulating in OR or Rocksim will tell the tale.

 

[GlenP]

Maybe I can get to Hawaii

I would first check the rated total max lift off weight for the first booster, not a hard and fast enough rule, but if you are near or nearly beyond that limit, then you need to do a more accurate check and be more cautious in light winds when launching a marginally too heavy rocket. Speed off the rod is the critical performance measure there to ensure the fins have enough airspeed to serve their function.

 

[Alan15578]

Many times you can just put a C motor into the top hole of a D12-0 motor. Back in the 70's before a certain person complained about this practice in Competition, we glued the two motors together to gain extra thrust from the empty D motor. I flew a few of those in competition in when it still was allowed. IN Fact the NAR newsletters at the time had articles and MATH on how it worked so well... They also had articles by very famous early 70's competition people on how removing the ejection charge from a B-2 motor allowed delayed staging to extra altitude for competition.

Edit: Just found the old memory cell location for what that was called, "Tandem Motor", if you don't glue it , it is still NFPA legal

So, tandemming motors. What works and does not work with the newer Estes motors, Say an E12-0+C6-7, etc. Asking for a fiend.

 

[lakeroadster]

So, tandemming motors. What works and does not work with the newer Estes motors, Say an E12-0+C6-7, etc. Asking for a fiend.

Fiend,
E motor's will stage exactly the same as D, C, B, etc motor's. Black Powder is Black Powder.
Happy Staging.
Lake

 

[Bruce]

A number of altimeters are now available for electronic staging of model rockets, that will fit in 18/24mm tubes, there's even one that fits in a 13mm tube.

This sounds interesting. We have an Altus Metrum Easy Timer, but it is for a 24mm tube.

Could you please share what specific staging altimeters/timers will fit in 13mm and 18mm tubes?

 

[smstachwick]

This sounds interesting. We have an Altus Metrum Easy Timer, but it is for a 24mm tube.

Could you please share what specific staging altimeters/timers will fit in 13mm and 18mm tubes?

Yes, please. If I could stage Q-Jet or Aerotech Ds in a very small tube, I’d be a very happy man indeed.

And probably a very broke man, too.

 

[Jeff Lassahn]

As well as the electronics I'm wondering what kind of small battery to use that has enough juice to fire an igniter.