Giant Leap Vertical Assault build thread.

Sorry you had a bit of a challenge with the nose shoulder flap. The ease and reliability of the technique can depend on the plastic thickness. I used about a 1.75" sq flap on my VA and with the thin plastic it was just ok, holding shape well enough with masking tape over to smoothly slide into the airframe. I did the same thing with a Madcow 2.6" nose which was much thicker and it came out a lot better.

A quick, pictureless update. I have finished filling the spirals (as good as I am going to get them with my low attention span). Now all that is left is sanding, painting, and drilling holes for the witch, static ports and sensor ports.

I may also end up putting the decal on. The black lettering won't show up on the dark blue, but maybe I will spray a yellow splotch on the upper stage and put the lettering on that.

Tonight I hope to finish the sanding. I'll post a "pre-paint" assembled picture if I do.

I guess this was a shameless "bump."

So, this is a terrible pic, I know; but I just couldn't find a good place in the house to shoot it. Anyway, this is what she looks like pre-paint, pre-drill. Next up: priming! Going to rain and rain here soon, so don't know when I'll be able to get to it. <sigh>

I got the primer on tonight. Duplicolor Sandable White Primer, from Advanced Autoparts. I put on six very light coats over the course of an hour, 10 minutes between each coat.

As I hoped but dared not say, it doesn't need any sanding! I love that primer for that reason. It goes on paint-sprayer smooth, and if you don't gunk it on too thick, it often doesn't need to be sanded. Yee ha!

Here are some pics. BTW, I built a stand out of a small piece of 1x6 and a 1" wood dowel. Attached the dowel perpendicular to the plank with a drywall screw.

Looking good!

Is it too early what kind of motor you are going to fire in it ?

Kenny

For a first flight, I think I'll go with a CTI J430 or J244.

Then, as I want to try for 10,000 feet, I am hoping a K600 will vindicate my building and finishing and get that baby up there. Next HPR launch is August 16!

Also, I was hasty in saying that it doesn't need any sanding. This morning I noticed the plastic parts were a little rough, so I will lightly sand the nose and fins with 400 grit. I'd use 600, but I don't have any.

I am leaving work early today to hopefully get the lower area, nose cone, and upper stage tube painted. Tomorrow if I can paint the remainder of the booster tube, then I will be ready for ground testing by the weekend. Just need to drill my holes.

Painting is finished ... well, for now. For some reason, the blue paint didn't apply well. I tried to follow the directions on the can; however, the humidity was probably 85% or higher when I was painting. Can't be helped around here.

I used anodized paint, Duplicolor Metalcast. You can see how splotchy it is.


I won't have time to fix it before launch on the 16th. Maybe I will repaint it with a different brand of paint, or maybe cover the blue parts in a wrap, or maybe leave it like it is.

What would you do?

Any ideas what fouled up the paint?

Here is what she looks like mostly done. Still need to add pressure holes, sensor holes, and a big hole for my rotary switch. Ground testing on Saturday.

I think the high humidity caused that. The directions on the can say no more than 50% humidity and under 90*. Metalcast is supposed to go over a silver metallic base coat, but I have had good results spraying it over Rustoleum white primer:

Batmite,

I had the exact same problem with the same paint same color and my humidity was good. I still intend to write them and complain. I put it over Duplicolor chrome, the chrome did fine, the blue fogged.

I painted over mine.


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I think I will paint my night launch rocket black ..

Kenny

Good to know about the paint. I also think I will paint over it, but not any time soon because I hate painting (and taping).

It is tough to paint here in MD because it is usually either too hot, too cold, or too humid.

But the Krylon yellow looks good.

Last update before launch! I drilled a 1/2" hole for my switch, three 5/32" holes in my AV bay for sensing pressure, and one 1/8" hole in each body tube for pressure relief. I am going to go with friction fit for main and drogue.

Switch hole and sensor ports (one in back)


Vent hole in upper stage


Vent hole in lower stage


Launch will be August 16, Lord willing. I'll post pics of that, and give a report.

Okay, well, today was the day. And this post will close this thread for me. I consider this, despite what happened today, to have been a very successful build and flight.

She went up straight and true on a J145 long burn, very stable, to a nice arc at apogee.


Drogue came out as expected, with a nice descent.


Main came out at 300' as desired. And I watched as it landed just on the other side of a big patch of reeds. Hmm, what could be beyond those reeds?


Turns out it was a pond. I had to fight through about 30' feet of deep mud (splooch, splooch, 4 or 5" thick), then hack my way through the weeds (6' high and about 20' deep), wade out into the pond (which was only waste deep), and recover.

The beauty is, the BRB900 and the RRC2+ were (and are) in perfect working order. Total, successful recovery--although soaking and filthy. Everything needs a wash.

Alas, due to a 1.5 hour back-up at the Chesapeake Bay bridge and the pond episode, I did not have time to try her on the K600. Next time!

And by the way, the great Neil McIlvray also put his rocket in the drink, so I don't feel so bad. :wink:

Congrats on your "successful" flight. What was the altitude?

"straight and true" ????
"very stable" ???

Im sorry, I was there Batmite, I do not think those words mean what
you think they mean, sir. Please do not put a sizable K motor
in that rocket w/o further test flights. Bad things might happen.
'Squirrelly' with a J(which is exactly what you had at the launch
yesterday) can sometimes turn into downright ugly with a big K.
In all seriousness, I'd go back to I's and see if you can determine
why it cork-screwed its entire way up to apogee yesterday, for safety's sake.
Ask the more experienced folks at MDRA to take a look at it and
see what insight they can offer.

-just my two cents.

Hmm... My Vertical Assault always flew straight and true regardless of the motor; never a hint of corkscrewing.

bill2654 said:

Congrats on your "successful" flight. What was the altitude?

Click to expand...

3121

G-Dog said:

"straight and true" ????
"very stable" ???

Im sorry, I was there Batmite, I do not think those words mean what
you think they mean, sir. Please do not put a sizable K motor
in that rocket w/o further test flights. Bad things might happen.
'Squirrelly' with a J(which is exactly what you had at the launch
yesterday) can sometimes turn into downright ugly with a big K.
In all seriousness, I'd go back to I's and see if you can determine
why it cork-screwed its entire way up to apogee yesterday, for safety's sake.
Ask the more experienced folks at MDRA to take a look at it and
see what insight they can offer.

-just my two cents.

Click to expand...

I don't recall it corkscrewing. Are you sure you got the right rocket? Man, I wish I had video, now.

Bat-mite said:

I don't recall it corkscrewing. Are you sure you got the right rocket? Man, I wish I had video, now.

Click to expand...

Pretty sure this is it. It was pretty squirrelly, enough to be a concern. And it seemed to develop the corkscrew more and more as the flight progressed at speed.


And before flying again, you'll want to properly rehab those electronics. Even though they were working after being dunked, they need to be cleaned, dried, inspected for corrosion, and tested before being flown again. If you haven't already disconnected the battery you should do so immediately to limit the damage.

Thanks, Bill. That is really helpful. I must have lost it in the sun as it neared apogee.

I am open to any and all opinions on what went wrong. The motor was a CTI 699J145. Dave Greger suggested maybe there wasn't enough thrust? Let's see if I'm doing this right. 1 Newton = 0.224808943 pounds. So 145 N = 32.597296735. 32.597296735 / 5 = 6.519459347, but the rocket came in at 8.2 pounds. So it wasn't enough thrust? I wanted low and slow, but I should have gone with more thrust, less impulse?

My other flew well on a J240 and an I285.

Next time I will retry it on the I285 and see how it goes. And I will make sure to ask someone to watch it with me.

Thanks to Glenn, Dave and Bill for pointing this out. It is embarrassing to have not noticed the corkscrews at the higher altitudes, but then I live my whole life in a kind of embarrassed state.

I'll get it right next time.

John,

I went back to the MDRA launch today and talked to one of the 'old timers' who happens to have
some experience with the pre-fab fincans. I described your flight characteristics and he suggested
the following... and again, this is w/o him actually laying hands on your rocket....

- while he could not be absolutely sure...he said it sounds as if you may not have the fincan
attached perfectly in alignment with the long axis of your body tube, and I believe he said he
knows this can be a problem from his own personal experience! And he added that, the longer the
body tube is, the more pronounced this misalignment would affect any given flight. And as I recall,
your body tube is pretty darn long for the Vertical. To verify this problem one way or another(either
you have it or you dont) he suggested an old r/c plane trick..and that is to take a tape measure like you might use to measure a length of wall or floor and measure the exact(!!!!) distance from the tip of your nosecone to
the upper/outer(!!) tip of each fin. Do this measurement for each fin. They should be exactly(!!!!!) the same
distance for all of your fins.... not just "thats close enough". If this distance is not the same for all fins, then
the fincan has been glued(??) on out of proper alignment and correcting might be difficult or impossible
depending on how you have attached it to the BT.

So, I would begin my search there if I was you...and I would stress John, that this search. on your part
is a very important and natural part of the post-flight evaluation we all do when a flight doesnt go as
planned. We're all better off for it.

If you are sure,on the other hand, that the fincan is on perfectly straight after measuring, then we just hit up the
old-timers for more input, Ive yet to meet one that charged a dime for it.

Thanks for advocating for me!

I need to spend an hour or so getting it cleaned up (it still looks like it was dredged up from a pond). And then I will do the measurement. That's a great idea. Thanks.

G-Dog said:

John,

I went back to the MDRA launch today and talked to one of the 'old timers' who happens to have
some experience with the pre-fab fincans. I described your flight characteristics and he suggested
the following... and again, this is w/o him actually laying hands on your rocket....

- while he could not be absolutely sure...he said it sounds as if you may not have the fincan
attached perfectly in alignment with the long axis of your body tube, and I believe he said he
knows this can be a problem from his own personal experience! And he added that, the longer the
body tube is, the more pronounced this misalignment would affect any given flight. And as I recall,
your body tube is pretty darn long for the Vertical. To verify this problem one way or another(either
you have it or you dont) he suggested an old r/c plane trick..and that is to take a tape measure like you might use to measure a length of wall or floor and measure the exact(!!!!) distance from the tip of your nosecone to
the upper/outer(!!) tip of each fin. Do this measurement for each fin. They should be exactly(!!!!!) the same
distance for all of your fins.... not just "thats close enough". If this distance is not the same for all fins, then
the fincan has been glued(??) on out of proper alignment and correcting might be difficult or impossible
depending on how you have attached it to the BT.

So, I would begin my search there if I was you...and I would stress John, that this search. on your part
is a very important and natural part of the post-flight evaluation we all do when a flight doesnt go as
planned. We're all better off for it.

If you are sure,on the other hand, that the fincan is on perfectly straight after measuring, then we just hit up the
old-timers for more input, Ive yet to meet one that charged a dime for it.

Click to expand...

I have been known to except a brew on occasion...:grin:

Bat-mite said:

... the rocket came in at 8.2 pounds...

Click to expand...

Was that with the motor ?

Kenny

KenRico said:

Was that with the motor ?

Kenny

Click to expand...

Yes.

I've been thinking about this a lot, and I think I can summarize things as follows. Here are the possibilities, and what I think are the likelihoods of them being the culprit:

• Underpowered motor. Can this cause corkscrewing?
• Canted motor tube inside. Most likely cause? But then how would the airframe fit over the CRs?
• Canted fin can inside airframe. Doesn't seem likely because the airframe slides over the fin can and fits pretty tightly to the CRS.
• Fins out of alignment. Least likely since this is a GLR factory-built fin can and would affect all VA rockets.

IMHO this may just be a combination of an over stable rocket and underpowered motor. On really tall rockets with smallish fins, it seems that at lower speeds the fins are not as effective at controlling the rocket, and this kind of tail wagging can occur. My Blackhawk 38 does it on low avg thrust motors - up the thrust, however, and it flies arrow straight. I would consider flying this on a lower impulse but higher avg thrust motor, say at least 7:1, to see if the corkscrewing persists.

On a side note, I have had a normally very stable rocket corkscrew once for no apparent reason. It was my 9' tall PML Black Brant X, it corkscrewed pretty strongly on an I327 DM with very little wind, and yet it has flown arrow straight on motors with both much more and less avg thrust...

+1 on long rocket underpowered. It is hard to make a build mistake on a Vertical Assault. Bump it up to a J240 or so.