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  #1  
Old 01-21-2016, 02:19 PM
Scott_650 Scott_650 is offline
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Default Russian R2 vs. German V2

Question for all you V2/A4 aficionados - I gather, from the reviews and flight reports I've read, that V2 models aren't easy to build as stable fliers. Does anyone know if there's been an attempt to build the second generation Russian version, R2 or S2 Sibling, as a flying model? The R2 is roughly 20% longer with a bigger fin span - would that be a better potential LPR performer? I'm a still green BAR with next to no experience building scale model rockets. Thanks!

J S Bryan
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  #2  
Old 01-21-2016, 03:46 PM
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LeeR LeeR is offline
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Bigger fins is a good thing, and adding length is also a plus.

I'm building an old Estes V-2 (2.6"), and the fins are definitely oversized.

I have a DML V-2 plastic model I plan to do a conversion on for flight. The fins on the Estes kit look quite oversized when compared to the fins on the scale plastic model.
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  #3  
Old 01-21-2016, 04:19 PM
PeterAlway PeterAlway is offline
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When I started researching data, I found some Eastern European sources that showed bigger fins for the Soviet R-2 than were on the original V-2, but on further research, I'm pretty sure that the Soviet R-2 had the same fin dimensions as the V-2. However, the R-2 was significantly longer, both in the body tube, and in the nosecone, which was close to a 4:1 ogive. I'm sure it would make it easier to make it stable, if only by providing more lever arm for nose weight. There were also American V-2's that were stretched by one diameter for Project Blossom. Again, these would be easier to make stable.

Peter Alway
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Old 01-21-2016, 05:19 PM
Scott_650 Scott_650 is offline
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Ok, the Project Blossom reference lead to some fascinating information - all those Albert monkies who didn't survive their trips in the Air Force's rockets! The mouse and the fruit flies made it back alive but I doubt they got a parade or anything.

A little more digging and I found out LOC Precision produces a HPR/MPR dual kit of the R2 and the Canadian Arrow X-prize entry and Estes offered an Arrow model as well that appeared to be a 4 inch and change stretch of the 2.6 in diameter kit. Whew! Just never know where building model rockets can take you.

Next step is to blow up the Currel paper V2 model and take some measurements - that should be interesting...I hope...
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Old 01-21-2016, 08:14 PM
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Rich Holmes Rich Holmes is offline
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To quote the late Carl McLawhorn: (http://rocketshoppe.com/forums/show...52&postcount=80):

Quote:
If you drill the nose cone deep enough to install 1/2 to 3/4 oz weight, the washer is not necessary. It is far too low at the base of the nose cone, anyway!

Extending the engine farther back will require slightly more weight, since that also moves the CG backward. The K-22 V-2 is so small for the weight of the engine, it is very hard to balance it with the scale fins. I don't know how it ever was stable back then.

For scale fins with a 2.5" deep 1/2" hole filled with lead weigh and C6-5 enginet:

.5 oz weight and no overhang .25 calibers
.5 oz weight and .25" overhang .16 calibers

.75 oz weight and .25" overhang .50 calibers

Just the included weight and screw eye and no overhang - minus .52 calibers!!

vs.

Semi-scale fins with included screw eye and weight .25" overhang - plus .5 calibers.
(He was talking about the Semroc clone of the old Estes K-22 18 mm kit. I started building one but never finished it because I was unhappy about the quality of work I'd done on it — I still do intend to build a little V-2 someday, a Semroc if they ever bring that back, or an ASP if not. I was using the scale fins and lots of weight in a deep hole in the nose, though the decision between that and the oversize fins was a near thing.)
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  #6  
Old 01-21-2016, 10:32 PM
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MarkB. MarkB. is offline
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Comrades!

I highly recommend the Estes BT-80 (2.6") V-2. I built it with scale fins (span was scale but they needed to be a little longer in chord) and the included nose putty and it flys rock solid on a D12-5. It's available on-line for less than $20--that's hard to beat.

I've built or repaired several K-22 BT-55 (1.3") V-2's over the years with scale fins and never had a problem; I drill a hole for a hardwood screweye mount, put some BBs under it with epoxy and call it good. I flew two with scale fins on A8-3s this weekend with no problems. That's them in the picture.

I've built the Semroc parts V-2 which, although based on the same BT-60/ST16 tube, is a little different from a Centuri V-2 in that Carl made his tail cone shorter and a little closer to scale and the body tube a little longer than the old Centuri kit. Randy has these parts for sale at eRockets. BMS has the parts for a Centuri V-2.

The key to any V-2 is balance; with the motor in, it should be slightly nose-heavy at the joint between the tail cone and the body tube. If you do this, scale fins are not an issue from BT-55 to BT-101.

With all that said, I'd love to see a Russian version!
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Last edited by MarkB. : 01-21-2016 at 10:57 PM.
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  #7  
Old 01-22-2016, 02:14 PM
PeterAlway PeterAlway is offline
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Quote:
Originally Posted by Scott_650
Ok, the Project Blossom reference lead to some fascinating information - all those Albert monkies who didn't survive their trips in the Air Force's rockets! The mouse and the fruit flies made it back alive but I doubt they got a parade or anything.


Here is a useful video of one of those Blossom flights that was extended one diameter:

https://www.youtube.com/watch?v=4U6YjPSiH3Q

The V-2 31 film, showing the extended version, starts around 11:35 and is in color. I recall from looking at that video and others is that the south fin (fin III, facing the camer in the first shots) is black on top on one side, and black on the bottom on the other side. The north fin (Fin I) is black on both sides. The east and west fins (fins II and IV) and the tail section overall were white. You can figure out the rest.

James Duffy's Rocket Aero videos are great resource for puzzling out White Sands V-2 color schemes.

Peter Alway
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  #8  
Old 01-22-2016, 04:51 PM
Scott_650 Scott_650 is offline
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So much great info! I think, like any good BAR, this is going to take multiple V2 variants. I have multiple projects in-work so this will be kit and material acquisition phase. I think a standard version will be first, I've never built a V2, then a build thread on a Project Blossom variation. The R2 version could end up being my first scratch built in 40 years. Thanks again for the great posts - you guys rock.
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  #9  
Old 01-23-2016, 09:52 AM
Taras Taras is offline
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Default R-2A fin dimensions

Here is a copy of the R-2A page from Minakov's scale book (2006 in Russian, three book series) that shows "official" dimensions of the fins.
Taras
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