R-7 Sputnik
 

After taking a break from my build of the 1/100 Saturn 1B using my wraps, I decided to go in another direction. I have always wanted to build an R-7 rocket. I have eyed Leo Cherkashyn paper rocket models for a while now thinking how I would convert them to fly. The only way to figure this out was to start building one. I have started out with Leo's Sputnik-1 8K7IPS model.

I started out scaling all the part to fit around a BT-60 tube. I plan on flying this model on a D size engine. I have modified some of the paper parts for easier assembly. I'm leaving off some of the smaller parts for easier construction, and the smaller part are more likely to come off on a rough landing.

I was wondering if the 4 boosters would act like tube fins? That way I could use the stock fins instead of making them larger. I still have to find the CP and CG points.

All and all I am enjoying this build. Here are a few pictures of the build so far.

Here is Leo Cherkashyn site. http://www.cardmodels-r.narod.ru/index-e.htm

Very neat work.

The boosters would have a somewhat fin-like effect. Kind of a complex conical shroud fin. But likely not enough that the stock fins would suffice.

You might consider nice large clear plastic fins with the scale fin skins glued on to them.

You may need to add a touch of noseweight but Roachwerks Soyuz and Vostok models fly in their scale configurations without enlarged or extra fins.

Agreed,

My R-7 models (same size as Roachwerks (BT-55 core) but not as beautiful) fly with more or less scale size fins without the least bit of trouble. Oversize or clear fins are completely unnecessary.

For an R-7, nose weight is more important than fin area. Your balance point is half way up the smallest (top-most) conical subsection of your boosters. It is absolutely critical to keep this build light. On the longer Voskhod and Soyuz, its not as critical as on the shorter Sputnik or Vostok.

Can't wait to see this. Please keep posting pictures.

Thanks for the support and suggestion gentleman. The thought about the fins I had got from reading BobH48 build thread. http://www.rocketryforumarchive.com...ead.php?t=41060

Thanks MarkB for the tip on where to locate the CG. That's a big help.
Working on an attachment for the nosecone at this point. Will post more pictures as I go along.

Had a little time to do some more work on the R-7. I glued the engine mount in place.
Added some small detail work to the rear end. Made a quick release engine bell mount for display.

Made a little more progress on the R-7 today. Got all the engines bell glued to the boosters.
Mounted the fin. They seem small but I am going to give them a try anyway.
I mounted the booster links to the main body. It wont be long before it all comes together.

Really nice building. I'm a sucker for a Sputnik. I built the Lars Folmann model years ago. Nowhere near as detailed as yours, though. I built it with a 13mm mount, but haven't flown it. I can't bring myself to attach a launch lug to it, and haven't got around to building a launch tower.

Can I ask what % you upscaled to get to BT60?

Hi Matthew, glad you like my build so far. It's slow going but its coming together. I can't wait to get it done, so I can do the first lunch. The nice thing about this model is if it gets destroyed I can start another. This kit will never be discontinued. That's the great thing about paper models.

About the scale. I am using the paper models Leo Cherkashyn created. His models are 1/48 scale in size. I use Photoshop Elements 10. I reduced his drawing from 100% down to 97%. This put everything in the right size to go with a BT-60 tube.

Ha. I didn't realise the original scale was bigger. I sit here looking at my little model and assumed yours started out the same. ;)

I found an old photo. I had just received my first ever order of APCP so put a couple of models in for scale.

http://australianrocketry.org/media...tmotors_800.jpg