V2 for my L3

Onebadhawk
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Dave A said:
I flew my first V-2 when I was 10 years old. I started back in the Hobby in '99 at 40 years old. Between my brother and I we have flown nearly every size V-2 from 3" to 7.5". Von Braun made an effective weapon. It had advanced motor and guidance technology, was short and fat so mobile launchers could take it it most anywhere to avoid the bombers.
Key words: It's short, fat and unstable compared to my 13' long IRIS.
I looked at the M-650 thrust curve and yes that 1250 newtons is there but only for a brief period. Regardless what the sims may show it will start to layover and look like it's headed to London. That kind of flight profile may have a higher velocity at apogee which you may not want.
I fly V-2s with somewhat flat thrust curves at about 7: 1 wt/avg thrust ratios. You get a nice leap off the pad and after burnout you get a nice , loud whistle near apogee, during that long coasting phase, that will impress the crowd.
If you want to do a test flight in the same case (assuming 6400n) fly it with an L-1170, then do your L3 with an M-1297 (with 1 AT spacer) or go for it with the M-1315.
Great looking build and finish, nice work!
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I see your point, and no doubt there will be more weather cocking with the M650 than the M1315. To save anyone interested the trouble I have pasted a pic below with the worse case (35 lb pad weight, probably be closer to 32 in reality) thrust to weight ratios marked. The M1315 does give it a harder kick off the pad, and keeps it about 7:1 thrust:weight for much longer (3.9 s versus 0.9 s), but the time above 5:1 thrust:weight is almost the same at (4.4 s versus 4.1 sec). I don't think I will be far off the flat 7:1 thrust curve you have gotten good performance at. Given your experience how much trouble do you think I'd be in during that first 4 sec? As the motor tails off I'm sure I'll see some degree of arching. Preventing damage from an off vertical flight/deployment is one of the reasons the fin can blows first and not the nose...should decrease the chance of zipper as everything will likely stay in line.

I'm not fundamentally averse to changing to the M1315, and holding the M650 back for next year's big project (75mm MD CF altitude seeker). The point of the M650 was for the long burn white fire/noise/smoke trail awesomeness. The M1315 will be way up there till it burns out at 5.5 sec though.

In the end I will work some of this out by discussion with my L3CC. Dave could safely fly a Borg Cube, and possibly put it into an RC controlled glide as well for that matter. If he isn't comfortable with the motor choice I will definitely wave off.

Thanks for the well informed advice. I do value such advice, even if I ultimately ignore it. :p

 
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ksaves2 said:
That might be prudent to get the cert in the can and do the M650 for later. Kurt
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This is a very valid point. For L1 and L2 I say just fly whatever you want, if you fail, try again. The L3 has so much extra paperwork that I really don't want to start fresh again. I have an email into my motor pimp to see what an M1315 would run me (along with the motor options to take my CF Mongoose 54 near/to 20k, my other planned Airfest flight), and what the lead time looks like currently.
 
Dave A said:
An M1315 is about $40 cheaper.
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I already have the M650 load though...like I said I have a backup plan for that motor anyway. Besides, the motor represents a relatively minor cost in this project. When people say L3 certs are expensive they are right.
 
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The green is masked off for painting the final color, hopefully tomorrow or Sunday. This color masking alone took 5 hours over 3 nights. I was pleased how the darker color minimizes the visible step that occurs between each section. I suspect with the colors breaking across the parts it will further disguise the body diameter discrepencies...I hope so anyway. Total useage was 2.5 rolls of Tamiya Tape, 1.5 rolls normal masking tape, 1 roll wide blue tape, and half a roll of masking paper...I mentioned I hate finishing, right?

 
Cl(VII) said:
Dave could safely fly a Borg Cube, and possibly put it into an RC controlled glide as well for that matter.
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Best thing I've read today.

So.youre spraying the lighter colors over the dark? Is it because the pattern makes that easier?
 
Nytrunner said:
Best thing I've read today.

So.youre spraying the lighter colors over the dark? Is it because the pattern makes that easier?
Click to expand...

When I did a test the finish on the brown was inconsistent when sprayed over the white, but good when sprayed over the green. The other reason to spray the brown last is cost. I'm using Testor's Model Masters at $4 for a tiny can.

Speaking of the paint job behold this morning's work product.

Sensitive eyes should look away, because this is definitely rocket porn. :drool:

 
qquake2k said:
You are a masking ninja!
Click to expand...

dixontj93060 said:
Wow, great job!
Click to expand...

Thanks guys. It all comes down to patience and Tamiya tape. With the most important part being Tamiya tape, that stuffs as no equal.

I painted the last two sections this evening. The fin can will have a couple sand and respray bits, but overall I'm pretty happy with it.

Edit: I think I just successfully sanded and resprayed the bad spots to the "close enough" point. Unmasking in about an hour as long as the fixes look good then.
 
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So, I pealed the tape from the other parts, and although there are some minor flaws it is perfect by my standards. Better than I ever thought I could do. Five cans of Testor's Model Masters Afrika Mustard was the final tally. Good thing for the 40% off Hobby Lobby coupon.



Even though the brown paint is still really delicate I couldn't resist putting it together. After I finished jumping around the room and giggling like an idiot ~5 solid minutes. I took the pics below of each side.



:cool::horse::cheers::marshmallow::w::headbang:

Thanks for the encouragement along the way. There are still some little things to do...rail button standoff, paint camera shroud (I put it at an intersection of three colors :facepalm:), re-epoxy a T-nut I broke loose in electronics bay, decals, etc. However, I think that concluded the heavy lifting. Only took a year and a half.
 
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Woohoo, man that turned out awesome! Very nice, 1.5 year, that's got to feel great getting that beast to that point.
 
Looks beautiful! I have been following your build and there is some serious craftsmanship under that paint....
 
Incredible job on this build Chris, it came out absolutely beautiful. Kudos on even attempting that ragged camo pattern, I surely would have gone crossed eyed just trying to mask it off. Looking forward to the L3 flight at Airfest.
 
Thanks for all the good words guys. I'm on the fence about spraying a coat of satin clear. I was definitely not going to, but the Tamiya tape changed the finish of the green slightly were it was applied. I thought I waited long enough between green coat, and masking, but I must have jumped the gun. It is only noticeable with a few feet, but I know it is there. I'll see how it looks in sunlight and decide then. I got spooked off clear coat when I had a perfect paint job crack entirely before. I probably didn't wait long enough between coats, but it spooked me. If this got hosed I'd be more than a little upset.

Edit: Just looked at it in the sun, and the tape marks are almost unnoticeable, so no clear coat.
 
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I have the full decal set from Mark for the Estes style markings, but many of them didn't look right when I was lining them up. As such, I'm going minimalist. Just serial numbers and off to the front to terrorize Amsterdam or London. If you look closely you will also see that I have put on the Motor Retainer as well.



EDIT: I realize you could take what I said two ways. "Didn;t look right" in this case means didn't visually fit the rocket as well as I would have thought, kinda looked kitschy. They were Mark's typical high quality, I just didn't end up liking the look.
 
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Cl(VII) said:
I have the full decal set from Mark for the Estes style markings, but many of them didn't look right when I was lining them up. As such, I'm going minimalist. Just serial numbers and off to the front to terrorize Amsterdam or London. If you look closely you will also see that I have put on the Motor Retainer as well.

Click to expand...

You will need either a Stahlhelm or a Pikelhaube helmet for launch Herr Doktor.
 
Amazing!
Arguably phenomenal even! (Sorry, inside joke.)

Will you bring it to the next DARS meeting?
 

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