Sprint - Test Flight 4 

I already told you, this is the only reliable roll maneuver: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-dQw4w9WgXcQ.html

Officer, this rocket didn't respect quarantine.

Can I just say, I find it super smart to present the launch before the monologue. This is the interesting bit, followed by why it was interesting - not everyone would do it in that order.

6:20 “And that is exactly what the data shows”

SṔⓇIÑⓣ

Seriously Joe, you’re doing some professional standard rocketry. Motor manufacturers excusing in-flight failures because most amateurs will never notice them is unacceptable. I sure hope you find a substantially more reliable source for your propulsive power. As for your roll sensitivity to pitch rate, if all you want to do is reach altitude, then it’s no problem. But if your goal is demonstrating the core competence of dynamic rocket guidance, then this needs to be solved. And many motors can handle radial loads. Maybe use a ball bearing motor (there are some excellent Swiss made small brush servo motors available). Maybe use a cheap bushed motor but mount the reaction wheel in ball races. Maybe drive reaction wheel motor with extra current, proportional to roll and yaw rate to overcome increased frictional torque. Maybe choose an alternative roll control scheme. Any way you choose, keep up the great work, it’s excellent!

Damn that TVC control is getting SMOOV

Famous NASA quote "... let's light this candle" Famous Elon Musk quote: "We're going to make it happen. As God is my bloody witness, I'm hell-bent on making it work". Famous BPS space quote: " ... ooop!" Excellent editing, by-the-way, you should give a few pointers to NASA. Timing the advancing data to the half speed footage is really informative. ... and cool!

ˋI rotated the vehicle 90 degreesˋ *shows 180 degrees rotation*

BUTTER love the tracking shots

Uhmmmm, that orange paint sure looks like something totally unrelated with a future rocket

That 17 second burn is gonna be awesome! Looking very forward to the results. Do you have an estimated altitude you think you'll achieve with it? If you're getting 163m from a 6 second burn, the new motor could net you 350-450m pretty easily. Good luck!

Carbonated Sprint

Joe, Thank you so much for sharing your videos with us. In the 70's I LOVED making and launching rockets. It was such a thrill. Watching your launches brings back that thrill. Be safe Joe.

Have you cut open casings of motors that seemed to have burned properly?

I love how you explain highly technical stuff in a way that a relative landlubber like myself can understand. Blue skies and calm winds to you sir. Thank you

Best tracking cam shot yet

Ah yes a new video from my favourite ballisitc missile builder :P

Absolutely love your content. A lot of effort and yet even better results. Keep it up

I love the way your system accellerates at a speed so much closer to scale than other hobby class rockets!!!

Another brilliant video Joe! Keep up the great work. Stay safe and carry on.

Love your shots, it looks so good.

I love the style of placing the launch at the start instead of talking for minutes like other youtubers. . .maybe it is your degree coming in handy, but it definitely keeps me engaged and then I am interested to hear all about the launch. Nice work!

Ive been watching your videos for as long as you've been making them and i can tell you're going somewhere

Joe, you are starting to make it look easy now. Great job!

From 7 to 17 seconds motor, cant wait to see that... amazing stuff!!

@Joebarnard Hey Joe.. this was the most stable flight i saw from all of your videos .. I literally just stood up and clapped on this video when it lifted-off and performed so well... Yes there was reaction wheel failure when it changed its course by a certain degree... But its a nice shot and this will lead you to more leaps

I liked that the reaction wheel is kind of like a fidget spinner when you pitch the spinner a bit you can feel that its getting effected and slowing down :).

Really interesting and incredibly well filmed (light and process) thanks!

Absolutely beautiful trajectory

Kudos Joe! Stay healthy.

Love it you have really fine tuned your aircraft really well.

Super interesting explanation on the momentum reaction during pitch over, thanks !

Pls only daylight shots in the future . This looks so much better :)

Great video. Though it may look like gyroscopic precession, the yaw rate which manifests once the vehicle starts to roll during the pitch-over maneuver might come from classical inertial coupling. N_ic=p*q*(Iyy-Ixx), where N_ic is yawing moment from inertial coupling, p is roll rate, q is pitch rate, Iyy and Ixx are respectively the yaw and roll moments of inertia about the CG. Because there's a large difference between Iyy and Ixx for rockets vehicles, fairly large moments can occur during maneuvers which combine roll and pitch rates. Likewise a combination of roll and yaw will result in a pitching moment. This would be fairly easy to model in Simulink and you could use your angular rate flight test data as inputs to your simulation. Assuming symmetry and integrating your total yawing moment (N=N_ic+(dr/dt)*Izz) you could estimate the expected yaw rate (r) during the maneuver. You'd also need a model of any commanded yawing moment due to thrust vectoring but that's pretty straight forward. The moments due to the aerodynamics might be a little more difficult but because your rocket is essentially neutrally stable Cmalpha and Cnbeta might be nearly zero. If not you could still estimate these derivatives and use inertial estimates for alpha and beta to estimate the aero terms. There's a great 1948 NACA paper by Phillips (NACA TN 627) which I believe discovered this in theory with a 5-DOF formulation before anyone experienced it in practice. Also Richard Day's "Coupling Dynamics in Aircraft: A Historical Perspective" is a good easy read for inertial coupling familiarization.

great work on that torque based thing you mentioned.

Wow! This project is Awesome!!!!

just an idea for you, add a shaft extension through the wheel to another bearing which should eliminate the sheer on the motor bearings.

Love the videos. Quick suggestion; when pointing at things in a close up, using a pointer or pencil or something would be a great way to convey what you’re gesturing at much more precisely. Good luck with the motors.

Just beautiful

I don't understand a single thing here. But, somehow I enjoy and watch every video.

nice flight ! congrats !!

It looks really cool man

I agree with your gyro motor shaft drag conclusion. Another thought, since you are not spinning this gyro in a vacuum, you are generating torque via aerodynamic drag on the flywheel. You should change from a spoked design to a solid disk shape with less aerodynamic drag from spinning. Keep 'em coming!

wow thought shut would not deploy very nice great job good looking model.

Quite hyped for that next flight ngl

I can see a Joe Barnard approved rocket motor in the works !

This is deeefinetely your quickest vehicle turnaround yet

Beautiful takeoff

Hey that's exactly what I thought was wrong with the reaction wheel/motor! You're faaaaaar better at explaining it, but I'm still feeling pretty smart right now haha.

Eyy, that's exactly what I said was probably the cause! I think a simple bearing support on the other end of the shaft for the motor would probably help. It'll probably still brake due to sideways force causing more friction, but at least you aren't getting the brutal bending force causing the motor to bind.

For the roll control problem, there are probably several solution: use ball bearings for the wheel and "decouple" the motor from it. Or use a small brushless DC motor which has ballbearings already and enough rotating mass that you could omit the wheel at all. Or drop the reaction wheel complete and go for two gimbaled rocket motor which could provide roll control - but could become mechanically challenging :). I like the pitch over manouvers a lot. They look pretty cool ..

I love your videos and one day I also want to build model rockets like you

Solid as a rock

Cool, where can I order it?

YES love this your work is awesome! Go for the moon

Could monitoring the RPM of the reaction wheel help solve the issue? If the flight controller detects lower RPM on the wheel, it delivers more power to compensate and bring the RPM back into spec. This would also allow a known amount of control at any given moment. Maybe switch to a brushless motor for better monitoring and control? A PID loop would probably be needed as well, but that is right in your wheelhouse. The draw back would be wearing out the bearings/bushings in the motors faster as they may not be designed for increased axial load. However, a low KV drone motor might get the job done. As always, great work. I really enjoy these videos.

Those late chutes scared me so bad

I look forward to more controlled thrust landing efforts too!!

If you support the end of the motor shaft with a bearing it will alleviate the side loads. Another layer on the motor mount so it is supported at both ends should do it

I feel like you are missing a lego astronaut looking out the “window” that can be seen with the onboard camera🤔

Respect bro

Well it’s not quite going so fast it begins to glow but I wouldn’t want it near any of my ICBMs, nice work guys

AHA I love the window!

Good job

you can use a BLDC and a dual ball bearing to absorb that axial force, also is a good idea to make your own motors, like KNO3 with sugar ones

Great flight and explanation. Now it’s time to use a larger motor....

Bro! Flatten that curve!!! You going to get us all killed...

That effect is something I have generally called binding [ or bearing binding], a good synthetic lubricant can help a little. It looked like a grain cracking to me.

Hey, there is still daylight! Nice one.

Cool video

You can add an axis support on top of the spinning wheel. This will get off the perpendicular loads on the axis.

Unsolicited, annoying military nit-pick: You've got the American flag oriented incorrectly. The stars should always be leading. Think of it as if the flag were on a pole and was trailing in the wind. The stars would be on the upper side of the rocket with the stripes trailing down. Awesome series, awesome rocket, great job! EDIT: Dude.... I cannot wait to see the G8 flight! 17 seconds! That'll really allow your TVC to stretch it's legs.

nice one Joe! those glasses makes you look even more smarther🤟

you are so crazy !! Dont Stop :)

Loving this series so far. Looking forward to seeing how the longer flights go. Slightly off topic, what software are you using to graph the data? Looks a little like Grafana.

Good job, keep it up! How is the motor attached to the reaction wheel? When it changed rotation direction that could have put a lot of torque on the binding, separating it

Are you going to print a new motor mount for the reaction wheel that incorporates a ball bearing support the motor shaft or do you have a different strategy?

I like how he always shows it like it's an ICBM launch.

very good

Perhaps trust vectoring is causing the engine failures. What kind of interia does the high velocity gases have? How does that change if you wobble the motor around? Perhaps it would be a good idea to Mark the x and y on the motor so you can know it's indexing relative to the rocket x and y.

Hey Joe great video I was looking forward to finding out what the problem was with the reaction control wheel, good catch. Is it ok that I miss the smiley face on the back of the motor?

You need a pair of thrust bearings on the wheel shaft to take the drag off the motor during maneuvers.

Maybe put a encoder on the reaction control wheel and run a control loop to reject motor friction during the pitch-over? You already have cutouts in the reaction wheel so a makeshift encoder to keep track of reaction wheel speed would be trivial.

Regarding the loss of roll control on the pitch over: If you want to relieve side load on the motor you might have to run the shaft *through* the wheel and anchor it on the outboard side as well.

Can you make the wheel almost be like a ball bearing inside the rocket so the motor shaft is stable and won’t move under pressure? Possibly smaller size inside of a casing.

I don't know if anyone thought of this, but when the roll happens it could do something to the motor, I don't remember who but I think it was the backyard scientist a while ago that made some spinning thing with weaker rocket motors and some had the propellant burn through the side of the motor

For constant thrust would it help to have a motor core that can be pushed down thru the housing to keep the position of combustion in the same place rather then having it burn deeper in to the housing. Could even be spring loaded.

Would you ever be able to downlink live data from the on-board sensors during flight?

If we want to measure the barometric pressure for measuring altitude, where to place the pressure sensor on the rocket to measure the exact change in pressure. And is there anything that we have to do calculation wise and coding wise to calculate the barometric pressure from sensor output values. Any answers for this ?

Bail on the spinning wheel roll control design. Use piezo electric gyros with active tail fin deflection to control roll. You can also delete the vectored thrust with this technology but in space the active fins will not work. And..... here now comes vectored thrust coupled with thrusters. I would keep the vectored thrust and run 2 active tail fins in atmospheric flight.

Great day light. Great day flight.

...what I would suggest is either two anguluar contact bearings (require preload) or 2 deep groove ball bearings to carry the flywheel... and maybe a sprag clutch to interconnect the flywheel and the motor so that the wheel can keep spinning if the motor stops...

excellent video .. !! What is the software that you use to make the graphs ...?

Can you anticipate the flywheel torque when pitching over and have the thrust vectoring work with it? When thrust vector(90): FlywheelSpeed = more

10:05 Still remains as my favorite Joey moment

In you base, where you have those fun diverters, can you add water? To enhance the lunch effect and in the future a mini deluge system :)

Can you put larger labels on the data graphs for the next time? Sometimes its hard to find out what is exactly being plotted without pausing the video. Great videos nonetheless, love the sprint series!

You could try constraining the shaft of the reaction wheel above the wheel itself. Perhaps if you find a bearing small enough, you could reduce the non-axial forces ability to 'bend' the shaft over to one side. Of course there will still be some residual force but I imagine it wouldn't be enough to affect the speed of the motor significantly

You are awsome!