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Steerable drogue chute?

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Dan Griffing

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Here's an example of both gravity turn and weather cocking. I launched a two stage M685W to K550W at XPRS (Black Rock) in 2018. I made a mistake and used a long burn (11.5 seconds) for the boost. Surface wind about 10 mph. Launched straight up, until it cleared the pad, then immediately was under the influence of the wind. The profile would have been much better with a higher average impulse motor for the boost.

And, the criteria of velocity and altitude was met for the 2nd stage to ignite - and it did.
The sustainer was traveling about 300 mph at 24 K' when the two 9" drogues from side bays were deployed. They held, but the shear pins for the main failed and the rocket drag separated. Got pretty ugly after that. At that point, the rocket was 4.1 miles downrange from the pad.

The nose with the GPS drifted back 6 miles and I calculated the high alt wind at about 75 mph from the profile and how far it landed from deployment. The descent track is just the nose/GPS with a 18" parachute.

After that, I began thinking about rocket designs that could help correct for these problems. Glad to have some good company.

View attachment 431289
Having good company isn’t having a workable solution.

The vertical control fin system can solve this in principle, but its really complex, and isn’t designed for near Mach speeds.
 

Richard Dierking

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Having good company isn’t having a workable solution.

The vertical control fin system can solve this in principle, but its really complex, and isn’t designed for near Mach speeds.
Yes, but as you know, some complex solutions start simple. There may be multiple paths to take here. The most important thing is that people like you are questioning and considering solutions.
Simple to complex. This why I'm a fan of open kinds of projects where information is freely shared and there are possibilities of developing from previous work. Why Arduino and other platforms are so good for our hobby.

For example, imagine if someone or a small group of people came up with a thrust vane system that could replace or add on to the aft closure of say 54 mm reloadable motors. It could even be a motor retainer with thrust vanes. And, the Arduino set-up (controller, gyro-accelerometer, other components) with open coding. Then, release it for others to try and improve on. There are some very capable people here and outside TRF.

I think many people don't feel comfortable tackling everything and team building here is challenging.
 

OverTheTop

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The vertical control fin system can solve this in principle, but its really complex, and isn’t designed for near Mach speeds.
I am curious to know why you think that vertical control fin systems are not suitable for near Mach speeds? My test-bed rocket for my VTS normally flies just under Mach, and well into the transonic region. The system is designed for speeds exceeding Mach.
 

Dan Griffing

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I am curious to know why you think that vertical control fin systems are not suitable for near Mach speeds? My test-bed rocket for my VTS normally flies just under Mach, and well into the transonic region. The system is designed for speeds exceeding Mach.
If I understood him correctly, JimJarvis50 said on the PID tuning thread, that the system his group had developed wasn’t designed for supersonic robustness and control.

From what I’ve heard about supersonic flight and control, the default assumption is that if you haven’t specifically designed for it, then it probably won’t work. It’s that demon that lives out there.
 

OverTheTop

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Ok, so doesn't cover all systems, and I agree with you regarding the issues if systems are not designed to work in that part of the envelope.
 

Dan Griffing

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Ok, so doesn't cover all systems, and I agree with you regarding the issues if systems are not designed to work in that part of the envelope.
My surmise is that most rockets aren’t suitable for supersonic flight just by adding a big enough motor.

But the propeller plane was necessary before getting to the jet.

There’s a lot of experience needed in working with competing configurations of fin control systems to see what’s most appropriate for controlling weather vaning and gravity turning in a robust way before doing it at trans sonic speeds. We don’t all have a NASA budget or their scientific brain trust to apply to the problem.
 

Richard Dierking

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The maximum velocity of the rocket back in post #16 sims at 1300 fps on a K520 which is my chosen motor. It will be moving faster on later 2 stage flights depending on results which could include destruction of course. I was thinking of having the control surfaces move to a neutral position during some phases of the flight; but only if this becomes necessary.
But, the first flight with this motor will not be a control flight, just the surfaces in neutral position during the whole flight.

And, of course they are not large forward control surfaces.

Again, probably thrust vanes are the best first thing to try commercially. I prefer thrust vanes over gimbal TC because you can control spin and larger longer burn motors are possible.
 

Dan Griffing

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Again, probably thrust vanes are the best first thing to try commercially. I prefer thrust vanes over gimbal TC because you can control spin and larger longer burn motors are possible.
As I see it, there are two categories of problems with thrust vanes: 1) Thrust vanes only work during the motor’s operation while the need to control the rocket such as to compensate for weather cocking is during the entire ascent phase.
2) Thrust vanes will make motors much more complex and expensive, which will require Aerotech and other manufacturers to project enough buyers to justify their R&D to develop and bring them to market.

On the other hand, small canard fin control systems can work during the whole ascent phase, and can be an add-on to many different rockets to work with a wide range of motors.

Instead of requiring a motor manufacturer to develop and sell them, many different rocket technology developers can work on different configurations independently or in collaboration.
 

BABAR

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Okay, how did we get from thread title, “Steerable drogue chute?” To “Transonic Vectoring Canards”?

We aren’t even in the same phase of flight, we started with recovery post deployment phase, now we are in boost or coast phase.

Time to start a new thread.

Hey, what’s this yellow stuff on my cornflakes?
 
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OverTheTop

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As far as steering back I think something like a Rogallo wing that is not too big so the sink rate is reasonable and has a decent forward speed. You could probably make it reasonably robust and able to survive sub-optimal apogee events if designed appropriately. I guess it won't make for a lightweight system once you add the steering as well.
 

BABAR

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As far as steering back I think something like a Rogallo wing that is not too big so the sink rate is reasonable and has a decent forward speed. You could probably make it reasonably robust and able to survive sub-optimal apogee events if designed appropriately. I guess it won't make for a lightweight system once you add the steering as well.
AND we’re back to recovery phase again.......
 

BABAR

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As far as steering back I think something like a Rogallo wing that is not too big so the sink rate is reasonable and has a decent forward speed. You could probably make it reasonably robust and able to survive sub-optimal apogee events if designed appropriately. I guess it won't make for a lightweight system once you add the steering as well.
This is actually what I was thinking up front. I am thinking it could be pretty small, given the sink rate is going to be two orders of magnitude compared to a Rogallo wing optimized for glide performance, in this case for the most part all we want is directional control
 

jadebox

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This is actually what I was thinking up front. I am thinking it could be pretty small, given the sink rate is going to be two orders of magnitude compared to a Rogallo wing optimized for glide performance, in this case for the most part all we want is directional control
Captain Obvious here ... If the 'chute doesn't glide, aiming it won't do anything.

That's one reason I have for questioning the idea of having a controllable drogue 'chute. On my rockets, the drogue doesn't do much more than just keep the parts of the rocket from becoming stable and falling straight down. In most cases, I think the drogue isn't even necessary.

I am not sure that a quick descent and guiding the rocket back toward the launch pad are compatible goals.
 

BABAR

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Captain Obvious here ... If the 'chute doesn't glide, aiming it won't do anything.

That's one reason I have for questioning the idea of having a controllable drogue 'chute. On my rockets, the drogue doesn't do much more than just keep the parts of the rocket from becoming stable and falling straight down. In most cases, I think the drogue isn't even necessary.

I am not sure that a quick descent and guiding the rocket back toward the launch pad are compatible goals.

392 mph for an RC glider do it for you?

What if the nose cone separated into a “lifting body” configuration (basically the part of the nose cone that ISN’T the lifting body comes off and dangles from the tether point
35814D1F-1AF2-44D6-A451-17EEA6B7495A.jpeg

One solid piece, designed to go fast (has the whole darn rocket yanking it down!)

Yes, it glides, but at a steep angle of attack so that the lift generates is the same as the DRAG of a normal drogue chute. Has tiny control surfaces (at the velocity it is moving, won’t take much surface area.)

Not designed to stall the downward velocity, just keep it within the same limits a normal drogue would have. The rocket post deploy is still going down, and going down very fast, but IF (and it’s a big IF) you can get the lifting body oriented and stable you could generate a controllable lateral vector aimed at your desired drop zone.

Since this is a thought experiment, I am just imagining. Certainly far beyond my ability.
 

jadebox

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392 mph for an RC glider do it for you?
I'm not sure why that's relevant.

My point was that if a parachute descends rapidly, there isn't enough time for the horizontal component of its motion to move it much distance back towards the launch pad.
 

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Hi Guys,

I’m a licensed private pilot. I use ForFlight aviation software on my iPad. You can obtain fairly accurate wind speeds at various altitudes. The wind direction is also provided.

Other companies also offer aviation software that provides this information. The flight planning software very accurately calculates the wind speed and direction into a flight plan.

I’m sure that there are rocketeers out there that are software engineers. They probably could develop a software product that could utilize the aviation weather data. This software may be able to tell you how many degrees off vertical a rocket should be launched off of vertical to compensate for the wind.
 

boatgeek

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392 mph for an RC glider do it for you?

What if the nose cone separated into a “lifting body” configuration (basically the part of the nose cone that ISN’T the lifting body comes off and dangles from the tether point
View attachment 431308
One solid piece, designed to go fast (has the whole darn rocket yanking it down!)

Yes, it glides, but at a steep angle of attack so that the lift generates is the same as the DRAG of a normal drogue chute. Has tiny control surfaces (at the velocity it is moving, won’t take much surface area.)

Not designed to stall the downward velocity, just keep it within the same limits a normal drogue would have. The rocket post deploy is still going down, and going down very fast, but IF (and it’s a big IF) you can get the lifting body oriented and stable you could generate a controllable lateral vector aimed at your desired drop zone.

Since this is a thought experiment, I am just imagining. Certainly far beyond my ability.
So one implementation of this idea would be a Starship-style belly flop with the fin can. If the canards are relatively far forward but just behind the break at apogee, you could in theory use the body tube as a glider body. Some up angle on the canards would keep the forward end up and the main fins would do most of the work of providing aerodynamic drag.

IMHO controls during the drogue phase are far more valuable than controls during the main phase. The rocket just doesn’t have as far to drift in the 700-1000 feet of descent under the main only. It may be hard enough to achieve that it’s not worth it though.
 

kbRocket

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Last year I developed some software that gathers upper level wind data from a NOAA forecast. Then I vertically integrate the data and combine with an assumed descent rate to plot hiking distance as a function height AG, projected forward for 6 hrs. This is described in a recent post: Winds Aloft Prediction

Here is an example for today at our club's launch site at Brothers Oregon for for a rocket falling at 75 ft/sec. A half line is 0.1 mile, full 0.2 mile, filled triangle is 1 mile.

BROHikingDistance.png
These are the corresponding winds:
BROWindForecast.png
It looks like a decent day to go high, except for the smoke from the wildfires.
 

Richard Dierking

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On the other hand, small canard fin control systems can work during the whole ascent phase, and can be an add-on to many different rockets to work with a wide range of motors.
Yes, and I think the first widely used system would (should) be a canard-type system. It just seems that offering something in say 3" and 4" diameter size in a package that would include the electronics & servos with control surfaces makes the best sense as an add-on for people with existing rockets. Again, the surfaces would not have to be large and shouldn't be because the add-on would affect the stability of the rocket.

We aren’t even in the same phase of flight, we started with recovery post deployment phase, now we are in boost or coast phase.
True, and I acknowledge and apologize for my part in that. However, my point is that if you are trying to keep flight profiles within the flight cylinder controlling the up part is important. I would think you would not want to have an apogee miles out and then try to get back.

This software may be able to tell you how many degrees off vertical a rocket should be launched off of vertical to compensate for the wind.
There are apps that provide pretty good info on winds aloft. However, there is wind shear and effects of near by mountains. As you know, the wind is seldom uniform even within a small geographic area. Again, depends a lot on the surrounding terrain.

And, it can be difficult to develop something like this. I've had 8 flights using side deployment bays and rocket coming down nose first. Highest was 25 K'. All successful up into destruction at XPRS 2018. I have completely re-built the rockets and now adding control during ascent.
Wish there were more people designing and building projects like the controlled drogue.
 

Dan Griffing

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On my rockets, the drogue doesn't do much more than just keep the parts of the rocket from becoming stable and falling straight down. In most cases, I think the drogue isn't even necessary.
In July I was using a small drogue with my single deployment Zephyr ahead of a ChuteRelease with the main.

In contrast to this a guy at the next table over from me was using only a main with ChuteRelease but with a much longer rocket. Because the rocket was so long, the leverage of the fins caused the airframe to streamline rapidly towards the ground trailing the chute, ChuteRelease, and nosecone behind the airframe. When the ChuteRelease allowed the main to open the shock caused a serious zippering in the airframe.

So drogueless recovery is not a good idea under these conditions.
 

Richard Dierking

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Dan and others, I suggest if anyone wants to develop something steerable and focus on recovery you may want to try ascent using a balloon. It might give you more options for testing days and locations. You could use a Featherweight Raven for specific altitude release (non-pyrotechnic please), and also include the FW GPS or another small/light system. Make sure it's a good system and you have lots of practice using it. In case of things like atmospheric thermals!

High Altitude Science has a variety of balloon sizes and kits for attaching payloads to balloons and filling them. Joseph is a nice guy and would be willing to help you. https://www.highaltitudescience.com.
Although, it can be a bit of a challenge to obtain compressed helium currently.

Quest for Stars is developing a return glider for recovery of high-alt balloon payloads. I've helped Bobby at several balloon launches. If you visit the website, check out the StratoShuttle. http://questforstars.com
You may want to reach out to Bobby for some suggestions and his experiences.
 

cerving

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So, maybe a "controlled ballistic recovery" using canards to steer the rocket in the general direction that you want it to go after apogee, followed by a streamer and a standard chute that come out at some point relatively close to your desired recovery location... might be doable, but it would take some altitude for it to work effectively.
 

boatgeek

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In July I was using a small drogue with my single deployment Zephyr ahead of a ChuteRelease with the main.

In contrast to this a guy at the next table over from me was using only a main with ChuteRelease but with a much longer rocket. Because the rocket was so long, the leverage of the fins caused the airframe to streamline rapidly towards the ground trailing the chute, ChuteRelease, and nosecone behind the airframe. When the ChuteRelease allowed the main to open the shock caused a serious zippering in the airframe.

So drogueless recovery is not a good idea under these conditions.
On several of my rockets, the drag of the chute in the Chute Release alone keeps the fin can at about a 15-degree angle above horizontal (fins lower than top). They tend to "fly" in whatever direction they were pointed when everything sorted itself out. That kind of setup with a very small drogue or streamer (or main in JLCR) might well be steerable so that it flies in the direction of your desired LZ. Obviously, you'd have to work out the drogue/streamer/parawad size to make the fin can take the preferred attitude.
 

Dan Griffing

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I suggest if anyone wants to develop something steerable and focus on recovery you may want to try ascent using a balloon.
Based on the responses I’ve gotten from this thread, I think that its not feasible to have an additional steerable drogue as an adjunct to using a fin control system to reduce the down range distance from the launchpad that a rocket—whose horizontal velocity component has by that system—lands.

Instead, what would probably be the simplest, would be a slight firmware change for the manual entry of an offset of distance and direction based on the overall effects of the wind during ascent and descent on the landing point from the launchpad.

Since the fin control system already uses an inertial guidance system to steer the rocket to eliminate horizontal velocity, this strategy would only be modified by doing the same thing—eliminating the same horizontal velocity—but at a direction and distance offset from where it would otherwise be doing so.
 

Dan Griffing

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So, maybe a "controlled ballistic recovery" using canards to steer the rocket in the general direction that you want it to go after apogee, followed by a streamer and a standard chute that come out at some point relatively close to your desired recovery location... might be doable, but it would take some altitude for it to work effectively.
No canard fin steering would be needed after the apogee — if the canard fin steering system had offset parameters for wind effect estimates for direction and distance entered before the flight.

The advantage of using this firmware modification is that standard, unmodified dual deployment hardware and recovery flight computers (like the Eggfinder Proton) could be used with the canard fin steering system, and that the canard fin system could be added as a modular section for some flights and not on others.
 

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Based on the responses I’ve gotten from this thread, I think that its not feasible to have an additional steerable drogue as an adjunct to using a fin control system to reduce the down range distance from the launchpad that a rocket—whose horizontal velocity component has by that system—lands.
I think it really depends on what your requirements are. I think it would be unreasonable to think a steerable high-speed drogue can reliably and accurately plop your rocket into a specific location.

But at the same time, lets assume at least SOME direction control was possible. I think at that point the standard high speed/low speed dual deployment configuration wouldn't be valid anyway. We'd have to look to completely different chute designs, rethink our desired descent rates from apogee, and come up with a flight profile that would work. The starting point to this endeavour would still be the same...... how can you make a GPS guided chute that's workable with a rocket. Then figure out what flight parameters that guidance is valid at, and design the rest of the recovery around that.

Now, if you also include a boost/coast phase stability control, then you've really got something. Set it to put the rocket in an advantageous wind conditon to give the 'chute system the best conditions to be steerable, and there goes the biggest potential negative.

Unfortunately, I'm nowhere near good enough to make any of this happen, and all I can really do from here is play cheerleader. Either way, the two systems working in tandem, in theory, would be a joy to see.
 

BABAR

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I'm not sure why that's relevant.

My point was that if a parachute descends rapidly, there isn't enough time for the horizontal component of its motion to move it much distance back towards the launch pad.
If you get a 1:10 glide ratio (1 foot forward for every 10 feet down—— reeeeeeeallllyy bad for a typical glider, but maybe not for a steerable drogue) for a 15k altitude flight that gives you almost 3 miles lateral direction. Then again, you might waste the first 5 k just trying to get the glider oriented.....

Parachutist’s “wingsuits” achieve a glide ratio of 2.5:1

 

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If you get a 1:10 glide ratio (1 foot forward for every 10 feet down—— reeeeeeeallllyy bad for a typical glider, but maybe not for a steerable drogue) for a 15k altitude flight that gives you almost 3 miles lateral direction. Then again, you might waste the first 5 k just trying to get the glider oriented.....
Wouldn't that only be 1,500ft lateral? Even then, could still be a huge win no matter how minor the return distance is.

Think if it this way. Take that same 15,000ft flight where the rocket is a half mile downrange at apogee, and a strong wind normally could have pushed it another 1-2 miles during its time under the drogue and chute. If a steerable drogue would even just halve that downrange drift it's a significant improvement.

-Hans
 

BABAR

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Wouldn't that only be 1,500ft lateral? Even then, could still be a huge win no matter how minor the return distance is.

Think if it this way. Take that same 15,000ft flight where the rocket is a half mile downrange at apogee, and a strong wind normally could have pushed it another 1-2 miles during its time under the drogue and chute. If a steerable drogue would even just halve that downrange drift it's a significant improvement.

-Hans
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No excuse, Sir.
 

jadebox

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... deleted ...

I didn't see the prior posts before replying.
 
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