Hybrids 2023

[Neutronium95]

Someone showed me these Aluminum Nitrous canisters. This should allow people to fly micro hybrids at Tripoli launches, since it's a replacement for the steel cartridges that micro hybrids usually use. It might even open the way to a certified micro hybrid, which might be interesting.

 

[cfb_rolley]

Someone showed me these Aluminum Nitrous canisters.

Yeah those are the ones a few of us have been trying to get in Australia to allow us to launch micros at club events, but so far, we don’t have a source.

 

[Hobie1dog]

for a rocket with a 54mm MMT, how long will the motor and tank end up being? 36 inches?

 

[Voyager1]

for a rocket with a 54mm MMT, how long will the motor and tank end up being? 36 inches?

For a 54mm Contrail motor you can get 28”, 36” and 48” motors.

Check out their site at https://contrailrockets.com/product-category/54mm/54mm-complete-motors

 

[cwbullet]

I might fly my first in 2024. Any suggestions on a kit that hybrid capable?

 

[Hobie1dog]

For a 54mm Contrail motor you can get 28”, 36” and 48” motors.

Check out their site at https://contrailrockets.com/product-category/54mm/54mm-complete-motors

WAY TOO expensive for me.

 

[cwbullet]

Way TOO expensive for me.

Over time, it is less expensive.

 

[terryg]

Hybrids are definitely an exercise in patience with all that is involved in setting them up and filling them. That said the buzzing sound of the launch is so very cool!

 

[OzHybrid]

I might fly my first in 2024. Any suggestions on a kit that hybrid capable?

A long one. My M900 2.5"OD 6 feet long. If RattWorks was still being manufactured......
This also means the Oxidiser tank will tend to be in front of the Centre of Pressure of the rocket. As the motor burns the stability will therfore USUALLY, decrease after launch.
My min dia goes from 15 calibres of stability down to 2 at its worst, back up to 7. OR or Rocksim do NOT model this......

 

[dhbarr]

A long one. My M900 2.5"OD 6 feet long. If RattWorks was still being manufactured......
This also means the Oxidiser tank will tend to be in front of the Centre of Pressure of the rocket. As the motor burns the stability will therfore USUALLY, decrease after launch.
My min dia goes from 15 calibres of stability down to 2 at its worst, back up to 7. OR or Rocksim do NOT model this......

Rocksim .rse format is supposed to allow this CG shift, and I believe RockSim supports it in the sim. I don't think OpenRocket does, even if a properly-formatted .rse is supplied. Could be very wrong about each of these points.

 

[OzHybrid]

Rocksim .rse format is supposed to allow this CG shift, and I believe RockSim supports it in the sim. I don't think OpenRocket does, even if a properly-formatted .rse is supplied. Could be very wrong about each of these points.

The rse file calculation info description for cg calculation says it's based on the change in weight based centrally on the motor length. Do you have a reference for this variable cg position change or a reference file for hybrids.? There is no RSE file for the rattworks M900 and the Contrail RSE file seems to be using a fixed CG position for each motor in the list with mass change being varied at that fixed point.

 

[rocket_troy]

Rocksim .rse format is supposed to allow this CG shift, and I believe RockSim supports it in the sim. I don't think OpenRocket does, even if a properly-formatted .rse is supplied. Could be very wrong about each of these points.

I can't speak for RockSim or OpenRocket (even though I have both), but for RASAero, there's no explicit mention of simulating this specific shift, however I've modelled a few large N2O hybrids (inc Karman Line shots) and I was surprised how close the CG points (modelled in RASAero) were to my CAD models simulating the tank and fuel grain depletion at various points of motor ops. Maybe a coincidence or a fortunate compatibility with the specific models to the shift, dunno...

TP

 

[OzHybrid]

I can't speak for RockSim or OpenRocket (even though I have both), but for RASAero, there's no explicit mention of simulating this specific shift, however I've modelled a few large N2O hybrids (inc Karman Line shots) and I was surprised how close the CG points (modelled in RASAero) were to my CAD models simulating the tank and fuel grain depletion at various points of motor ops. Maybe a coincidence or a fortunate compatibility with the specific models to the shift, dunno...

TP

Depends on where the nitrous tank sits relative to the CP. With the M900 being so long, a lot of tank was forward of the CP.

 

[rocket_troy]

Hybrids are definitely an exercise in patience with all that is involved in setting them up and filling them. That said the buzzing sound of the launch is so very cool!

That's not an inescapable inherent issue that can't be avoided or at least significantly mitigated though. Back in the 90s, N2O hybrid GSE was indeed painful to setup, deal with and as a legacy, much of that kit and design philosophy is still around today.
However, some of us have streamlined things enough to render the process not much more onerous than flying solids.

TP

 

[rocket_troy]

Depends on where the nitrous tank sits relative to the CP.

CP has nothing to do with the shift in CG. Note: I was specifically focussing on the shift in CG during a burn.

TP

 

[OzHybrid]

CP has nothing to do with the shift in CG. Note: I was specifically focussing on the shift in CG during a burn.

TP

True, but the problem is magnified by the relative positions of the rocket cg and the motor cg as it burns. The change in the overall rocket cg might not change too much if the motor average cg was close to the rocket cg.

What have you done to streamline ground support then? Liked that quick fill release. What else have you got up your sleeve?

 

[rocket_troy]

True, but the problem is magnified by the relative positions of the rocket cg and the motor cg as it burns. The change in the overall rocket cg might not change too much if the motor average cg was close to the rocket cg.

What have you done to streamline ground support then? Liked that quick fill release. What else have you got up your sleeve?

Nothing I haven't already discussed here. The big thing is the GSE controller (about a ... dunno... 80mm x 60mm x 60mm box) that can be carried around mounted via a strip of plastic to the tank. Still have the 2 solenoids, but a push-in hose connection that most people probably use these days. So, fill the tank via RF remote and fire with club's existing controller.
Of course, it also helps having a dual deployment system that can be prepped in 30s

TP

 

[OzHybrid]

Nothing I haven't already discussed here. The big thing is the GSE controller (about a ... dunno... 80mm x 60mm x 60mm box) that can be carried around mounted via a strip of plastic to the tank. Still have the 2 solenoids, but a push-in hose connection that most people probably use these days. So, fill the tank via RF remote and fire with club's existing controller.
Of course, it also helps having a dual deployment system that can be prepped in 30s

TP

Don't know how I missed those posts...... I'll be stealing a couple of ideas. It's a compliment....

 

[ContrailRockets]

for a rocket with a 54mm MMT, how long will the motor and tank end up being? 36 inches?

The mono motor is 36 inches long. The spiral thrust washer is .5 inches from the end of tube. You can download the 54mm manual from the Contrail Rockets website. The standard top bulkhead extends above the top of tube by 1.5 inches but the weight reduced is flush with the top of the tube.

 

[anbhtblr]

I might fly my first in 2024. Any suggestions on a kit that hybrid capable?

I agree, 2024 will be a great time to explore this option. I want to see a list of what design features that make a rocket hybrid capable.

 

[dhbarr]

The rse file calculation info description for cg calculation says it's based on the change in weight based centrally on the motor length. Do you have a reference for this variable cg position change or a reference file for hybrids.? There is no RSE file for the rattworks M900 and the Contrail RSE file seems to be using a fixed CG position for each motor in the list with mass change being varied at that fixed point.

https://www.rocketryforum.com/threads/openrocket-center-of-mass.160821/#post-2157656

 

[OzHybrid]

https://www.rocketryforum.com/threads/openrocket-center-of-mass.160821/#post-2157656

Thanks.
When I did it, in 2013, I just created a bunch of equal masses along the length of the oxidiser tank. A fixed mass for the remaining fuel grain and a bunch of masses in the same spot at the centre the fuel grain position.
Remove an oxidiser mass and a fuel grain burn mass as a pair, one pair at a time. Think I used 10 masses for oxidiser and fuel and that gave me enough info to find out how much trouble I was in.
For the flight sim, I just used the RASP file for RattWorks M900 as there wasn't a RSE file. At that point I knew where the CG was going and the assumptions being made using the RASP file didn't affect anything.
I found that method to be pretty easy. It doesn't really matter when the cg change occurs for the flight, just that it stays in front of the CP for the full flight.

 

[Voyager1]

I might fly my first in 2024. Any suggestions on a kit that hybrid capable?

Many kits can be easily modified to accept a hybrid motor. Depending on the length of the motor, you can use some of the shorter hybrid motors without modifications.

For example, my 38mm Contrail motors range from 16” to 36”. The 16” one fits nicely into the sustainer stage of my Double Shot (used as a single stage) without modifying, except for a 3mm hole in the body for the vent line. The 36” motor fits into the same body, but requires an extension to the booster airframe. This one also requires a 54/38mm removable centering ring to support the forward end of the motor.

My 28” 54mm Contrail motor fits into the booster section of my 4” MC FrenzyXL without modifying, except for a removable 98/54mm centering ring, again to support the forward end of the motor.

 

[Troy3003]

Anyone planning to fly their hybrid at MWP? I will probably do one flight on a M1491 load if I get all my gear together this week. Below is my L3 flight on the same motor/different rocket. Had some oxidizer loading issues so ended up being a partial fill. Noise wasn’t noticeable until you get the burnout. And no it didn’t go into the clouds, the video is kind of deceiving.

 

[TurbulentSphere]

Someone showed me these Aluminum Nitrous canisters. This should allow people to fly micro hybrids at Tripoli launches, since it's a replacement for the steel cartridges that micro hybrids usually use. It might even open the way to a certified micro hybrid, which might be interesting.

I got in my box of 50 today and they fit in the Micro Hybrid. The neck is a little different, and it feels like a slightly tighter fit on the diameter, but I think they should work. Time to fly some Pringle motors...

 

[Voyager1]

Someone showed me these Aluminum Nitrous canisters. This should allow people to fly micro hybrids at Tripoli launches, since it's a replacement for the steel cartridges that micro hybrids usually use. It might even open the way to a certified micro hybrid, which might be interesting.

This might be a show-stopper for micro hybrids if it comes our way!

https://www.gov.uk/government/news/nitrous-oxide-to-be-illegal-from-november

 

[rocket_troy]

This might be a show-stopper for micro hybrids if it comes our way!

https://www.gov.uk/government/news/nitrous-oxide-to-be-illegal-from-november

But there is some common-sense to it:

"Licences will not be required to carry nitrous oxide, but individual users will need to demonstrate they are lawfully in possession of nitrous oxide and not intending to consume it for psychoactive effects."

TP

 

[Jeremy Sim]

I got in my box of 50 today and they fit in the Micro Hybrid. The neck is a little different, and it feels like a slightly tighter fit on the diameter, but I think they should work. Time to fly some Pringle motors...

View attachment 610591View attachment 610592

Want to send some to Australia for me??

 

[Chuck Rogers]

I can't speak for RockSim or OpenRocket (even though I have both), but for RASAero, there's no explicit mention of simulating this specific shift, however I've modelled a few large N2O hybrids (inc Karman Line shots) and I was surprised how close the CG points (modelled in RASAero) were to my CAD models simulating the tank and fuel grain depletion at various points of motor ops. Maybe a coincidence or a fortunate compatibility with the specific models to the shift, dunno...

TP

As OzHybrid noted:

<< The rse file calculation info description for cg calculation says it's based on the change in weight based centrally on the motor length. >>


RASAero II uses the same type of model. Loaded, expelling mass as the motor burns, Unloaded (Burnout), the Center of Gravity (CG) of the motor is at the one-half point of the motor length.


It's not so much a coincidence, as just assuming that the motor CG is at the one-half motor length point is a pretty reasonable assumption.



Charles E. (Chuck) Rogers
Rogers Aeroscience

 

[TurbulentSphere]

Want to send some to Australia for me??

I don't know if they will ship it there, but there are some on ebay: https://www.ebay.com/itm/354586001388