battery or alternator?

[chas9]

I need to run an accessory on my UAV Im designing as a group project. It requires 24-28 vdc and put out 58 amps.

Are there any batteries this small or what else could I do?

[kd7ost]

58 Amps at 24 to 48 vdc? Holly cra*. What are you guys powering? Can't you get rid of some of that power requirement?

Dan

[chas9]

well, it's a tactical uav....so a minigun. :)

[kd7ost]

UH huh,

Guys building a UAV with a Mini gun without the knowledge to power it. Yep, I'm all over that one. :)

Dan

[chas9]

FYI. 7 senior AE students in the design class....I think we have plenty of knowledge to build it. Especially since we are starting from scratch. This is only the design phase. So everything is hypothetical. Don't get so anxious

[kd7ost]

I disagree. This is from my own experience. If you're starting from scratch you have a long way to go and will face issues to resolve that you aren't even yet aware of.

If you were serious and had the budget you need to even pull off such a project, and were serious about it, and had any knowledge of what the community at large here even would think about such a venture, (Whew, breath) You would have an engineeer on staff to resolve these issues and keep it to yourself.

The very nature of your question speaks volumes about where you're at.

Start with a paint gun and see if you can even pull that off.

And, I'm one of the nice guys. :)

Dan

[clolson]

Is this a 2nd semester project or a year long project? Time will escape quickly on you, especially if any of your team has other classes to deal with at the same time. How heavy is the gun? Maybe a couple marine batteries in series will give you enough power? You'll want to come up with a total payload weight pretty quickly so you know what size to build your airframe and how to power it.

[chas9]

I understand what you are saying. But you don't know from experience. Especially if you aren't an aeronautical engineer. This isn't a little homebuilt slap some stuff together in a week and say cool project. It's a well thought out process that takes a long time and a lot of man hours.

There is a specific design process however. It involves coming up with a take-off weight for your vehicle, before any concept, sketch, or design has even been thought of. Then you calculate performance characteristics based on those weights. And the actual design is towards the end.

Thanks anyway though. I was just trying to get an estimate for weight. Most vehicles the weapon is on (helicopters), use the motor for power, and some have batteries. I was just trying to find out what they might be using. I just contacted the manufacturer of the system and waiting to hear back.





And clolson: The gun weighs 45.1 lb. It will be mounted similar to a A-10. There are many UAV's we have been looking at with similar mission profiles and equiptment. All together they weighed from 150-800 lb. 2 semester project. 1st semester is all design and number crunching. 2nd is testing model in windtunnels and then some type of prototype. I'll tell you what, there is a lot of time that has to go into this. 24 hours a week is a about what we are told to spend on it. Hurts when you are taking 4 other 300-400 level classes

[lvspark]

You could mate one of these 7.4's (http://www.maxamps.com/Lipo-10000-74-Pack.htm) with a one of these 18.5's (http://www.maxamps.com/Lipo-10000-185-Pack.htm)

And chas9 give these guys some room to answer and ask questions. Thier experience and wisdom far exceeds thier post count. ;)

[clolson]

And clolson: The gun weighs 45.1 lb. It will be mounted similar to a A-10. There are many UAV's we have been looking at with similar mission profiles and equiptment. All together they weighed from 150-800 lb. 2 semester project. 1st semester is all design and number crunching. 2nd is testing model in windtunnels and then some type of prototype. I'll tell you what, there is a lot of time that has to go into this. 24 hours a week is a about what we are told to spend on it. Hurts when you are taking 4 other 300-400 level classes

Having worked at a university and having seen several sets of aero students go through a similar process I think I have some idea of what student groups are able to accomplish in a semester. (And certainly I don't have absolute knowledge of this, every group and every individual is different, and a lot depends on how much real time you can actually devote to the project, how much past experience your group has with similar projects, how much time you have to wait for parts or supplies to arrive, how much budget you have, versus how much scrounging around through old junk around the shop you have to do, etc.)

That said, it sounds like you will need to build an airframe that is starting to approach the size of a small homebuilt manned aircraft. From that standpoint, you might want to calibrate your expectations of cost, and time, and shop space, and materials around what you might expect for a small home built aircraft.

I honestly think that's a tremendous amount of effort to bite off for one semester, unless you guys have done a similar project before and know what you are getting yourself into.

Just for point of reference, we've had student groups come through that were unable to successfully build an RC airplane and fly it in one semester. Our labs are littered with broken wreckages of past projects. Maybe 1 project in 5, or maybe 1 project in 10 actually successfully completes a full flight and returns to the lab intact. It's my personal opinion that this university could use better mentoring, and indeed, recent projects have generally been more successful.

Hopefully you guys have better intuition than some of our students, but I've seen groups forget to glue their control surface hinges and have pieces depart in flight. I've seen groups fail to balance their models before attempting flight. I've seen linkages that were incredibly loose and wobbly (on a twin 0.90 size design with 10' wing span ... again with pieces departing in flight.) I've seen fuel and fuel-line problems and crashes trying to dead stick back to the field. I even saw one group that used a chunk of 2x4 (the real pine kind that you'd use to build a house with) as a landing gear spacer to get enough prop clearance off the ground. I could go on and on, but all these groups crunched the formulas and verified their design was sound, but then lacking much RC modeling experience eventually made a critical mistake that lead to disaster.

Regards,

Curt.

[chas9]

Don't get me wrong. I am in here because I need help. I know no one means any kind of disrespect. It is a little hard when the subject goes off topic and my competency is challenged.

[chas9]

very good point curt. Fortunately, the instructors at the school are very prepared in the industry and in research. The machine shop foreman is also very helpful. Cost is part of the analysis and presentations/reports, and everything will be taken into account. Every semster the 2nd semester design class builds their prototype and they have flown everytime from what I have seen. If the machinist guy or the instructor saw us taking shortcuts they'd notice.

I fly RC aircraft by the way. I got a trainer for christmas a couple years ago and have been playing with that since then.

[clolson]

Well best wishes for your project. I'd love to hear how things went at the end of the semester (with pictures of course.) :-)

Curt.

[chas9]

I will keep all informed, definately!

Thanks all for the help.

[RolandS888]

Where's patrickegan?

[fnev]

Why do I feel so uncomfortable with such tread??? Please refer to the FAA qualification thread. If you are serious about these things (because these have very serious implications), please keep it for yourself and do you homework within your connections.
As some said it is a very ambitious project. Very few systems are able to achieve this. I mean in reality, not on paper…

Your power requirement would indicate that you are not only working on designing an airframe to carry a gun, you are looking at the whole system INCLUDING navigation and mission profile. It takes YEARS for a well geared up company specialized in UAS to make a demonstrator that WORKS…

GOOD LUCK!!!!

[spitfiremk9]

Well I would not be giving this joker any info, period! This is supposed to be a civilian forum not an encyclopedia that any old gung-ho-shoot-em-up nutcracker can use. There must be a special forum somewhere else for this kind of sh*t, try Noddy land.

[chas9]

Why do I feel so uncomfortable with such tread??? Please refer to the FAA qualification thread. If you are serious about these things (because these have very serious implications), please keep it for yourself and do you homework within your connections.
As some said it is a very ambitious project. Very few systems are able to achieve this. I mean in reality, not on paper…

Your power requirement would indicate that you are not only working on designing an airframe to carry a gun, you are looking at the whole system INCLUDING navigation and mission profile. It takes YEARS for a well geared up company specialized in UAS to make a demonstrator that WORKS…

GOOD LUCK!!!!



As far as FAA qualifications there would not need to be any. The aircraft would fall under the experimental category. This project/class is all on paper basically, and then in the fall we build a model. Obviously the model is not going to have a live firearm on it, So I would really appreciate this forum getting their panties out of a bunch.




Well I would not be giving this joker any info, period! This is supposed to be a civilian forum not an encyclopedia that any old gung-ho-shoot-em-up nutcracker can use. There must be a special forum somewhere else for this kind of sh*t, try Noddy land.

It is people like you that don't deserve a computer. I would rather not stoop to your level and demeanor. I don't appreciate your remarks and comments, and they are very unnessesary. Have some respect and keep it to yourself.

You don't know me, the school, or the group. As well as the abilities of the three.