school committee has changed things ALOT!! (electronics ideas)

[Lt72884]

Most of you know by now that 4 members and I of my school's aerospace engineering course has been tasked to build a HPR that can hit 10,000 feet and carry 9 lbs and follow all spaceport america cup guidelines even if we are not competing, oh, and we do not have a mentor. We have contacted about 15 people and none of them want to be a mentor. Makes us sad, but we now rely on ourselves. Here is the newest update. we have contacted another university that did place in the SPAC last year and they are willing to try and answer questions without giving away their ideas...


Ok, the last few weeks i have not been active on the forums due to our school committee changing the team rocket project extensively. Besides building a level 2/3 rocket that can hit 10,000 feet with a 9 lb payload, they have tasked us to make a ADS (active drag system) system. This system is to help us hit EXACTLY 10,000 feet. They want some sort of design that happens right before 10,000 feet to cause drag and slow us down so that apogee is 10,000 and ejection happens. This is all due by march for first launch. There are no launches between now and then for testing in my state. I have told the committee to "let us focus on one or the other. either let us buy a rocket kit and let us focus on the electronics or visa versa" they have said the rocket must be from scratch.

I can sit here and complain all day about how the committee basically hosed us over, but at the end of the day, we still need to turn in a capstone project so we can graduate from aerospace engineering school

so here is my simple question, after you know the back story... Are the ANY active drag systems we can at least buy to practice with and get an idea of what to do? we need something to start off with?

thanks

 

[Hobie1dog]

google brings up quite a bit on it:
https://www.google.com/search?q=roc...i57j33i160.20574j0j7&sourceid=chrome&ie=UTF-8

 

[Lt72884]

google brings up quite a bit on it:
https://www.google.com/search?q=roc...i57j33i160.20574j0j7&sourceid=chrome&ie=UTF-8

wow, i didnt think it was an actual term hahaha, i would have googled it myself. I thought it was a term made up by my school committee who are not all engineers haha. thanks

 

[MClark]

In the real world if a contract required this it would be returned as "No Bid."
The cost just went through the roof with chance of success near zero plus no return on investment.
Tell the school No.

 

[OverTheTop]

I tend to agree with MClark unfortunately. This is an enormous task. Many hurdles and challenges with no rocketry experience. Chance of a successful outcome minimal without support. Sorry .

FYI, the biggest improvement in achieving a target altitude is to build the rocket and do a test flight. That allows you to select the right motor and adjust ballast for tuning the altitude.

 

[Lt72884]

I tend to agree with MClark unfortunately. This is an enormous task. Many hurdles and challenges with no rocketry experience. Chance of a successful outcome minimal without support. Sorry .

FYI, the biggest improvement in achieving a target altitude is to build the rocket and do a test flight. That allows you to select the right motor and adjust ballast for tuning the altitude.

yeah, i agree with all of you on this. I cant tell the school no or i fail. I have told them its impossible and dangerous.
so we are going to make the rocket and ads and just tell them next years team will have to do the rest

 

[Hobie1dog]

did you watch the Youtube videos and read the articles that comes up on Google?

 

[Lt72884]

did you watch the Youtube videos and read the articles that comes up on Google?

yes i have. I sent them to my group as well for ideas.

thanks for those

 

[FredA]

These Captstone projects are ridiculous.
Next they will be asking for perpetual motion machines....."or you don't graduate"....what a pile of un-constrained BS.
Don't think I'd goto a school that requires such nonsense.

 

[prfesser]

Thinking a little outside the box...and depending on how the committee has stated their wishes (in writing, perhaps with enough wiggle room for this approach)...

Is there an altimeter that could be programmed to *deploy* at 9.9k feet ("if pressure =< 525 mmHg*** then deploy")? Design rocket to go a bit higher than this. Deploy a stout drogue (or just pop the nose) at 9.9k. It's active, it produces drag. Second altimeter deploys at apogee JIC rocket doesn't reach 9900 feet.

DO NOT ASK if this approach is permitted. Just make sure that whatever approach is used actually falls inside their rules. And apologize after.

***need the actual pressure, this is an estimate.

 

[cerving]

It's VERY difficult to hit an "exact altitude"... there was competition at LDRS a few years ago for that, and even with total control of the altimeter's deployment software I failed miserably. There are a lot of things involved... some of which you can't control, like variances in the performance of the motor from one sample to another.

 

[cls]

What a ridiculous situation. Well, make something that will fly, and recover safely, but design intentionally so it won't meet any of the criteria. Just say it is not possible to do safely.

 

[Steve Shannon]

TARC teams tried (probably still do) to use active drag to hit a precision altitude. NAR has contests for precision altitude. As I recall, the old Raven had the ability to fire at a particular altitude on ascent because that was a (human) error mode some people reported. Other altimeters probably do also.

Capstone committees should be required to demonstrate that they can perform whatever idiotic task they assign.

 

[boatgeek]

I would basically take @prfesser's idea and set your altimeter to deploy at 9.95K feet. Any 3+ channel altimeter that can do airstarts will do. For sure a Raven, an Eggtimer Proton, and the new Eggtimer combo tracker/altimeter can do that, and likely others. I would arrange it so that the primary drogue charge has two ematches, one to the "airstart" channel at 9.95K feet, and one to the regular drogue deployment channel in case you don't make it to 9.95K feet. That way, either charge will separate the rocket. I would also have a backup altimeter with independent charges.

And yes, the requirements are ridiculous. Therefore, I don't feel bad at all about doing a malicious compliance minimum effort response.

 

[Mason T]

@Lt72884 what is the specified tolerance on the desired altitude? Everything on engineering has tolerance. In this case is it plus minus 1000 feet 100feet 10 feet 1 foot, 1 inch, 1thousandth of an inch. It makes all the difference from possible to your out of your mind.

And a quick work on capstones. I’ve never seen someone not graduate from their capstone not working. As long as you put a genuine effort and have put in the engineering to achieve most of it I’m sure you will graduate. If they didn’t pass everyone who didn’t achieve perfection then graduation rates would suffer and it would hurt the “business” one thing you will learn is the business will always come first. I have heard plenty of school admin complain about being forced to pass x numbers.

 

[OverTheTop]

It's VERY difficult to hit an "exact altitude"... there was competition at LDRS a few years ago for that, and even with total control of the altimeter's deployment software I failed miserably. There are a lot of things involved... some of which you can't control, like variances in the performance of the motor from one sample to another.

So many variables, but you can get quite close with a lot of diligent work. Test flight is a must, as is sensitivity analysis, adjustable ballast, and a little luck. The university team I mentor hit 30k' with an error of 67' this year, and in 2019 hit 10k' with an error of 27'. In the case of the 30k' flight a launch rail angle of 2° cost approximately 50', otherwise we should have been around 17' error.

@Lt72884 what is the specified tolerance on the desired altitude? Everything on engineering has tolerance. In this case is it plus minus 1000 feet 100feet 10 feet 1 foot, 1 inch, 1thousandth of an inch. It makes all the difference from possible to your out of your mind.

In competitions closest to the altitude wins. No tolerance required. In OP case it is a design constraint and would only be a minor consideration if otherwise successful.

 

[JoePfeiffer]

I'm pretty sure the leadership of any number of rocketry organizations would be happy to write letters telling your committee that their requirements are unreasonable and unsafe.

 

[Mason T]

So many variables, but you can get quite close with a lot of diligent work. Test flight is a must, as is sensitivity analysis, adjustable ballast, and a little luck. The university team I mentor hit 30k' with an error of 67' this year, and in 2019 hit 10k' with an error of 27'. In the case of the 30k' flight a launch rail angle of 2° cost approximately 50', otherwise we should have been around 17' error.

In competitions closest to the altitude wins. No tolerance required. In OP case it is a design constraint and would only be a minor consideration if otherwise successful.

@OverTheTop I believe this was a capstone project not a competition. I believe they were given a list of specs from the professor.

 

[OverTheTop]

@OverTheTop I believe this was a capstone project not a competition. I believe they were given a list of specs from the professor.

Yep. I can read, therefore the second statement in my post #16 applies.

 

[ThirstyBarbarian]

I guess I’m not familiar with capstone projects. It’s an engineering project required to graduate? This sounds like a ridiculous and unfair number of requirements for a project that can’t be tested in the timeframe you have.

My first idea for the braking system is to have something that doesn’t gradually slow the rocket to hit the altitude. Instead, just slam on the brakes at the right time. You could use a rear-eject recovery setup or a zipperless design and something like a kevlar chute. Pick a motor that would hit 11,000 feet and deploy the recovery on the way up just short of 10,000.

Unforunately, that idea would put a huge amount of stress on the rocket. I’m not sure how you would design the compartments for the main chute and the payload so that it wouldn’t all just separate during the jolt.

 

[Sandy H.]

I believe, at times, it is helpful to pose a challenge that is absolutely impossible and for the student (or person challenging themselves) to clearly and eloquently explain why the challenge is impossible. In order to accurately explain why the challenge is impossible, a lot of work needs to happen and in the process of doing that work, real self-education happens.

I'm not suggesting that your capstone committee is doing that, necessarily, but I know for my capstone project the professor (not committee) knew me well, knew my areas of interest and knew way more about any of it than I did. He absolutely gave me a ridiculous goal and I tried to solve it. After a handful of weeks, I presented him with all of the problems and he sat back, smiled and told me I'd be a great engineer. We then came up with something interesting to test and he had the full belief that whatever I came up with he could have faith in. Similar things have happened during my career - sometimes the ridiculous goal is actually impossible, but sometimes it has changed the company's bottom line by +10-20mUSD.

The work and questioning everything is no different if your trying to figure out how to do the impossible or the "I haven't done that yet". The end result may be very different, but my advice would be to simply take the problem you have been assigned with and figure out how it could be done and each time you reach a concern, educate yourself about the options. Once you have completed the process, do it again, questioning your own answers. After you prove to yourself the various outcomes, you will have achieved a level of expertise - not necessarily being 'an expert' - but you will at least be qualified to have an intelligent conversation with someone who has 30 years of experience doing what you said can't be done and you can learn from them how to do things better and move the ball forward yourself.

So, you either have a very benevolent and well educated capstone committee or you have a bunch of lazy people you need to educate by providing great information. Oddly enough, the task on your end is the same, the work you do is what matters and ending your presentation with "and that's why this task can't be accomplished." is absolutely OK, as long as you clearly demonstrate why the task is impossible.

All the above is my opinion only, however my capstone mentor helped reinforce life lessons my father gave me, so at least one time in history, I can say for fact that giving an impossible task lead to positive direction and I thank both of those people (and a few others) for the life education I have had.

Sandy.

 

[teepot]

How about deployable air brakes. 2 or 4 panels deployed 90* to the rockets direction. Think air brakes on a jet fighter. F15 comes to mind.

 

[JoePfeiffer]

It should be noted that everything they're being asked for is very standard in Spaceport America Cup so it's not impossible -- but one of our criteria for accepting teams is enough experience that they have a good chance of success.

 

[Lt72884]

ok, its been about a week or so since this post. I have talked to them and told them it is going to be unsafe if we do not change a parameter. So now the focus of capstone is to build a ADS system and have next years team build the spaceport america cup rocket and hopefully use the ADS system.
They are allowing us to buy a kit rocket that is level 3, since we are lvl 2 now(except me hahaha), and use that kit as a testing rocket for the ADS, and a template sort of speak for next years rocket team.
So as of now, we are all on the same page. I was up till 2 am last night helping them see the hurdles.

 

[Handeman]

ok, its been about a week or so since this post. I have talked to them and told them it is going to be unsafe if we do not change a parameter. So now the focus of capstone is to build a ADS system and have next years team build the spaceport america cup rocket and hopefully use the ADS system.
They are allowing us to buy a kit rocket that is level 3, since we are lvl 2 now(except me hahaha), and use that kit as a testing rocket for the ADS, and a template sort of speak for next years rocket team.
So as of now, we are all on the same page. I was up till 2 am last night helping them see the hurdles.

Sounds like you were able to get the committee to see some sense. That's great.

I think I understand how a capstone project is supposed to work, but is it possible to get some of the underclassmen involved if they are supposed to used what you develop next year? From what I've seen of college teams, one of the biggest issues they deal with is loss of knowledge every year when the seniors leave and in many cases, the folks that are left have to re-invent the wheel the next year. It's why we see some of the same failures from the same teams year after year after year.

Good luck on your project.

 

[Lt72884]

Sounds like you were able to get the committee to see some sense. That's great.

I think I understand how a capstone project is supposed to work, but is it possible to get some of the underclassmen involved if they are supposed to used what you develop next year? From what I've seen of college teams, one of the biggest issues they deal with is loss of knowledge every year when the seniors leave and in many cases, the folks that are left have to re-invent the wheel the next year. It's why we see some of the same failures from the same teams year after year after year.

Good luck on your project.

yup, its a loss of knowledge every year because we do not know who is going to take capstone next year, or what capstone project they get. There are 13 projects from a fish sorter to sort june suckers from utah lake, to a guitar pedal, then our rocket and ADS.
I gave tje hand book of model rocketry and another book to my professor as a starting point and notes. I own both books so i gave them to him so he can use them to teach from. I have told him that a requirement for next year is to have the students read the books, join these forums, talk to me, use the barrowman equitons, use open rocket, learn the rocketmime site for basic examples, and most importantly, do a selection of students in april so they have time to prepare and meet deadlines for spaceport. None of this, 2 weeks into september and your on the rocket team haha.

yes, i am very glad they saw the sense and understood. Our report will be super short this semester, but they will have to deal with it

 

[OverTheTop]

yup, its a loss of knowledge every year because we do not know who is going to take capstone next year, or what capstone project they get.

This is a problem for all teams, and succession planning should come into your thoughts when designing the rocket and other systems. Documenting decisions, hardware and other procedures is key to this.

 

[gldknght]

I guess I’m not familiar with capstone projects. It’s an engineering project required to graduate? This sounds like a ridiculous and unfair number of requirements for a project that can’t be tested in the timeframe you have.

Especially since they keep changing the requirements...