ULA Atlas V X Honest John

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High Impulse
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Re: ULA Atlas V X Honest John

Postby High Impulse » Sun Jul 31, 2016 4:37 pm

Thanks OTT, that data was exactly what i needed :)

Did some quick volume calcs and I think Ill have just enough room to fit the 0.5 inch stuff when I stuff a J motor in the mount. If i end up running short on space I'll just have to use kevlar for when I fly bigger motors.

Parts are ordered now :D so hopefully construction in the near future.

Cheerio,

Adam
L1: Callisto - H410VM

High Impulse
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Re: ULA Atlas V X Honest John

Postby High Impulse » Sun Sep 04, 2016 7:49 pm

Hi all, good news is that I got the parts for the build last friday so thought i would post an update to respark the build.

Bad news is the parts arrived at the busiest time of semester so probably no construction for me for the next 3 weeks :(

Here is the general layout compared to my callisto for a bit of scaling. Im a bit worried about how big it is, it looked a whole lot smaller on the computer :O

rocket.jpg


Also, Im a bit concerned about my fins, when i originally designed them they looked fine. but when i compare them to the actual thing they look a bit tiny.

Currently, as the sim stands with no weight updates it has about 1.43 cal of stability with the biggest motor in the pipe. However, i expect when I add my electronics etc will bring this closer to 2 cal. I know over 1 is required, but is 1.43 cutting it a bit fine?

If need be i can add some bigger fins, but if anyone thinks it will be fine i might just leave them. I do intend on L2'ing on it, so I would prefer to err on the side of caution though

Cheers,

Adam
L1: Callisto - H410VM

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Re: ULA Atlas V X Honest John

Postby High Impulse » Tue Jan 03, 2017 8:32 pm

So after much umming and ahhing, I’ve got my act together and have started construction. I was, and still am, concerned about the weight, but if I play my cards right it should be still suitable for large H motors through to just about any 6 grain 38 I can get my hands on. Currently its standing at about 2.5 kg unloaded but thats with about 500g estimated for electronics etc so it may change.

Prior to any work being done fins were washed down and all parts sanded with what I think was 120 or 80 grit sandpaper. Whatever it was it gave a nice bonding surface. Dry fit was then commenced and everything was fairly tight.

For the fin can the PML removable rear centring technique was employed to hopefully improve my chances of better internal fillets. I have tried the Wildman injection method before but found it just makes a horrible mess so its back to something I know well.

2.jpg


Top centring ring was tacked in place with 15 minute epoxy and held vertical to cure. Then fins were tacked on with 5 min araldite which is about as far as I have currently got thus far. To help with fin alignment I printed out a guide from http://www.payloadbay.com/index.php?pag ... =FINGUIDES and stuck it to some cardboard boxes I’d cut up and stapled together. Then cut out the template with a hobby knife and used a protractor to help check it was all square. As a result of my not so perfect dremelling of the fin slots my fins will never be perfectly aligned, but I tried to keep them consistent so that it will at least fly straight, albeit with a bit of spin.

7.jpg


8.jpg


On that note, I was wondering how people slot their fins? Ive got access to a drop saw, bench drill and dremel, but nothing that’s all too precise.

In addition, nylon piston strap and nomex shock cord protector have been glued to the motor mount. Im holding off putting the 3 inch piston in place as I am still trying to decide how to attach my launch lug standoffs. If I use a piston I will have to epoxy them on, but am worried about them shearing off due to the rockets high CG causing a large moment at take-off. If anyone has a neat mechanical way to attach launch lugs effectively to a body tube that still utilizes a piston I would be very grateful for knowing about it.

Furthermore, the fabrication of parts for the complicated transition/coupler has begun. To help improve the blow molded transitions resistance to bending moments (the contact area that holds the whole aircraft I connected together at is currently very small) 3 ply wood rings were cut with hole saws (so they are rough as guts), but they will be epoxied together and then probably screwed to the transition (as seen below) to help improve the bonding contact area.

5.jpg
4 inch coupler with reinforcing rings inside


4a.jpg
Assembled transition with supporting rings to increase glue contact area


That’s all for now, hopefully the lower airframe will be done soon and then the transition can be assembled. At the moment I haven’t finalised the length of the upper payload bay, but will do that once I have done a full fitout.

I was also wondering what is a cheap alternative for charge wells? I have seen some guys use spent out D motor casings and I know wooshtronics used to sell some (but I think they might not be operating anymore?) but I am open to any suggestions

If you guys can see any flaws in my current progress/design please let me know as I haven’t built anything for 6 months or so and as such I am a bit rusty. In particular, is about 6m/s descent rate reasonable for mains? Also what would be a good drogue descent rate, ive never flown dual deploy before so setting up the rigging/descent rates for this is a mystery for me and if there was any good online resources for this would be great.

Thanks again,

Adam
L1: Callisto - H410VM

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SpaceManMat
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Re: ULA Atlas V X Honest John

Postby SpaceManMat » Wed Jan 04, 2017 9:40 am

Looks good.
6m/s is a normal landing speed.
Probably want to be 4 to 5 times faster under drouge.
QRS: 124
AMRS: 32 L2 RSO
Highest Altitude: 10,849 feet
Largest Motor: CTI 1115J530 IM
Current Project: X Wing

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Re: ULA Atlas V X Honest John

Postby OverTheTop » Thu Jan 05, 2017 11:38 pm

If you are using GPS tracking consider setting main deployment a bit higher than traditionally done. It gives more time for a valid packet to be received at the GSE as the rocket comes back to Earth. I have been setting 1800' lately. If you have a smaller cylinder to work in you may want to lower this a little. Depends on max altitude and how far you expect to drift, worst case.
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High Impulse
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Re: ULA Atlas V X Honest John

Postby High Impulse » Fri Jan 06, 2017 1:22 pm

Thanks Matt :)

I'll make some adjustments to my drouge size to keep the speed around 25 - 30 m/s ish


Cheers OTT, I will keep that in mind when I set up the RRC3, 1800 ft drop on mains at QRS's site is normally pretty good in terms of walking so i'll start out at that altitude and move down as need be.



Speaking of QRS, are their normal rails 2.6 m long? Just wanted to double check i had my sims all fine for take off speeds

Thanks guys :)
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SpaceManMat
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Re: ULA Atlas V X Honest John

Postby SpaceManMat » Fri Jan 06, 2017 3:03 pm

High Impulse wrote:Thanks Matt :)

I'll make some adjustments to my drouge size to keep the speed around 25 - 30 m/s ish


Cheers OTT, I will keep that in mind when I set up the RRC3, 1800 ft drop on mains at QRS's site is normally pretty good in terms of walking so i'll start out at that altitude and move down as need be.



Speaking of QRS, are their normal rails 2.6 m long? Just wanted to double check i had my sims all fine for take off speeds

Thanks guys :)


Keep in mind that people do fly drogless, so really faster is not much an issue. Main consideration is to keep the av bay below the drouge however I find attaching the chute to the end of the shock cord keeps everything in the right position.

After my AMRAAM flight at QRS (main shook out at about 2k feet) I'd be setting the main for 800 to 1500, of course if I had a tracker this would not have been an issue...

QRS rails are 1.7m the big one is 3.2m
QRS: 124
AMRS: 32 L2 RSO
Highest Altitude: 10,849 feet
Largest Motor: CTI 1115J530 IM
Current Project: X Wing

High Impulse
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Re: ULA Atlas V X Honest John

Postby High Impulse » Mon Jan 09, 2017 8:05 pm

True, but faster means more shock on the airframe, which is not something im looking for. I just want to avoid a 2 km hike to go get my rocket ;)

Why do you need to keep the av bay below the drouge? does it stop things getting tangled when the main deploys?

Thanks for the rail lengths, they will adjust my minimum motor size a bit :( oh well, more excuses to fly I motors then


I am up to doing my external fin fillets, which shouldnt be to bad but ive been too tired after work to do all the required prep so in the meantime I thought i would get started on some recovery gear.

Speaking of which, I want to run a piston in the lower airframe to allow for simple motor ejection for shakedown and low altitude flights. As such my main shock cord is only about 1.2 m long (extending from the motor mount) and will be epoxied to the piston. However, I have just had a slight concern, will there be any issues regarding me firing my electronic ejection charges from above the piston in the future when i run dual deployment? I will have to protect the chute with nomex which isnt a problem, but will the mere act of having a piston sitting below all the recovery gear have any influence?

From a force balance point of view i cant see any issues, unless of course the electronic charge and the motor ejection charge fire simultaneously (then I'll have a very energetic recovery), but am I overlooking anything critical?

Cheers :)
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SpaceManMat
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Re: ULA Atlas V X Honest John

Postby SpaceManMat » Mon Jan 09, 2017 11:32 pm

If you fall too fast then the upper body may hit your drouge and yes the main chute may be deployed into the drouge causing a tangle.

Too slow can be an issue as well, if the nose cone is pointing down.
QRS: 124
AMRS: 32 L2 RSO
Highest Altitude: 10,849 feet
Largest Motor: CTI 1115J530 IM
Current Project: X Wing

High Impulse
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Posts: 279
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Re: ULA Atlas V X Honest John

Postby High Impulse » Sun Jan 22, 2017 6:25 pm

Thanks Matt, it appears as though i will be doubling the risk with dual deployment, but oh well live and learn.

I have some more progress to upload later on but for now I have come across something peculiar. I have epoxied my motor retainer on with JB weld. Initially I let the epoxy set overnight and it was solid as a rock. However, the surface was still slightly sticky to the tough and could be easily indented. Is this a result of poor mixing or not enough hardnener?

to be on the safe side i carefully mixed up a new batch to ensure i had the right ratio and smeared it over the top of the cured epoxy (after roughing the surface up a bit). Then after leaving it cure for 24 hours I still have the same issue whereby the epoxy is set and hard, but the surface is mildly tacky. So either my measurment of epoxy was off (i was eyeballing it), perhaps there was another factor involved or do i need to leave the JB weld longer before it is fully hard to touch?

Does anyone have any suggestions as to what the source of this issue may be and if it may compromise the strength of my bond?

Thanks heaps,

Adam
L1: Callisto - H410VM


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