K-41 Mercury Redstone Project

[MarkB.]

Next project: A real, live, Estes K-41 Mercury-Redstone.

I thought it was long gone, but my dad found the bag in the back of a storage box, called me and said "Guess what I found . . . ." I started it when I was a little shaver back in 1975 but quickly realized it was beyond me. Now, all is not perfect: the weird little sheet of dowels for the tower has disappeared as have the rings for the tower, the shock cord is rotted and the instruction sheet is gone, but the capsule and engine mount construction from 1975 has held up remarkably well. I ordered replacement decals from Gordy as there's little chance the original sheet is still good.

Using the original balsa sheet I tried to make the famous six piece fins. After much fiddling and salty language, I decided to make a one-piece base fins and use the plates and vanes from the originals. The fillets are outlined in cardstock and I'll build them up with Fill-n-Finish and CA glue. Using some David Weeks drawings, I added cardstock details to the fin can.

I'll post some more pictures as I go along, but really, this will be all about the escape tower. If anybody has the diameter of the little dowels, I'd love to know. I downloaded the plans from JimZ but they don't say.

[ghrocketman]

Semroc used to offer laser-cut pieces for the 6-piece fins. I bought a few of those sets for my K-41 kits.

[A Fish Named Wallyum]

Awesome! I would love to see how mine really turned out. I remember being very impressed back in 1978, but it didn't take much to impress me back then. I do have an original capsule as a place to restart. :cool:

[MarkB.]

Well, I did it!

The photo shows the completed pieces for the tower. It's built of 1/12 dowel and toothpicks. It turns out that the toothpicks are very close to 1/12 themselves. I might consider redoing this with smaller diagonals if I ever find smaller diameter dowels.

Both rings were gone so I made the smaller one using SWMBO's punch set. The larger one is a peeled 24mm engine block that I stripped both the inner and outer paper from and then sliced it in half with a razor saw.

Having built both, I'd put the 38 piece Soyuz interstage as slightly more difficult to build than the 29 piece MR escape tower structure only because the Soyuz is structural and there is a fair amount of weight above the structure; on the MR it's only a small balsa dowel for the escape motor.

I'll post more soon.

[Questor]

A Twoer, A pun? Made of toothpichs :chuckle:

[MarkB.]

Duly edited. That's what I get for posting late at night.

[Bill]

The photo shows the completed pieces for the tower. It's built of 1/12 dowel and toothpicks. It turns out that the toothpicks are very close to 1/12 themselves. I might consider redoing this with smaller diagonals if I ever find smaller diameter dowels.


I have had decent luck making smaller dowels by twirling them through decreasingly smaller holes in a drill gauge. It takes a bit of practice, but finding the gauge was the hardest part.


Bill

[MarkB.]

It occurs to me that one of the definitions of Insanity is to repeat an action with the expectation of different results . . . .

So, I wasn't happy with how the tower came out on a number of levels:

1) It was too wide at the base;
2) The diagonal pieces looked very heavy;
3) The glue joints were a mess and because of extraordinarily high humidity over the last two weeks, they had never quite set properly.

So I took it apart and started over.

This time, I used the Robert Blaske drawings from the Ninfinger website. I still used 1/12 dowel for the long runners and the short cross pieces but deviated from the Estes instructions and went ahead and added the bottom-most cross piece that touches the cap of the capsule. This made the partially completed tower MUCH stronger.

I'm still working on Bill's suggestion of pulling toothpicks through the drill gauge to create 1/16 dowels for the diagonals. In the meantime I'm working on the escape motor. The motor will be a 3/8 " dowel with cardstock wraps and details. Pictures in the morning.

[Bill]

I'm still working on Bill's suggestion of pulling toothpicks through the drill gauge to create 1/16 dowels for the diagonals. In the meantime I'm working on the escape motor. The motor will be a 3/8 " dowel with cardstock wraps and details. Pictures in the morning.


If you have trouble making them, I can send you some.


Bill

[NAR29996]

You can make small dowels with this tool: http://www.micromark.com/jewelers-draw-plate,6942.html. I'm still honing my technique, but it seems that it should get you the dowels you need.

[mojo1986]

You can make small dowels with this tool: http://www.micromark.com/jewelers-draw-plate,6942.html. I'm still honing my technique, but it seems that it should get you the dowels you need.

I bought one of these for that specific purpose but had less than satisfactory results. Unless the grain of the dowel is EXACTLY parallel to the sides, the dowel eventually gets too weak at the smaller diameters to be pulled through holes without breaking.

[stefanj]

How I make skinny dowels:

https://farm8.staticflickr.com/7205/6824363562_01e482c4c7_n.jpg (https://flic.kr/p/bp3DwJ)Tower Dowels (https://flic.kr/p/bp3DwJ) by stefan_e_jones (https://www.flickr.com/people/99668169@N00/), on Flickr

I got the dowels at a craft store.

It takes many tries to get a dowel right (that is, fits in the feeler gauges in the Apollo capsule cardstock tower jig. Sometimes you'll get only 1/2" or so of usable dowel.

[NAR29996]

I bought one of these for that specific purpose but had less than satisfactory results. Unless the grain of the dowel is EXACTLY parallel to the sides, the dowel eventually gets too weak at the smaller diameters to be pulled through holes without breaking.

Thanks for the tip. I haven't gone that small yet. I may need to use a different material should I ever need to.

[Bill]

You can make small dowels with this tool: http://www.micromark.com/jewelers-draw-plate,6942.html. I'm still honing my technique, but it seems that it should get you the dowels you need.


I was not aware of those, but it is essentially what I am doing with a drill gauge.


Bill

[Bill]

to get a dowel right (that is, fits in the feeler gauges in the Apollo capsule cardstock tower jig.


Those feeler gauges are somewhat oversized from what is specified in the instructions.


Bill

[MarkB.]

Here's a quick update picture.

The Redstone is now resplendent in Rustoleum Gloss White. If you look carefully near the fins, you can see some of the cardstock details which I think look great. Next step is to paint the roll pattern then add Excelsior decals from Sandman.

I built a third wooden tower. Then I put it off to the side as the 1/12 dowels looked big and clunky. Even using Bill's technique to thin them some didn't really help. At my local hobby shop I found some carbon fiber lengths in the bargain bin in .08 and .04 sizes so I'm going to try that next.

[mojo1986]

The MR looks great! The only thing about carbon fiber is finding a glue that will stick the stuff.

Joe

[ghrocketman]

I have two K41's new-in-bag and another that has been opened but complete.
I have not built one since about 1983.
Have Semroc laser-cut fin sets for all 3 kits.
Might build one this winter.

[MarkB.]

OK, Comrades, prepare to be blown away!

In the picture below you see my K41 Capsule which has sat patiently (more or less constantly since 1976) while I have tried to build escape towers having long since lost the pressed wood that came with the kit. I have tried dowels, toothpicks and carbon fibre. And while carbon fibre showed great promise for a traditional build, I struggled mightily with adhesives. The project has basically just sat still since the early part of the year.

As I mentioned in another post recently, I have seen the future and it is 3d printing and sure enough, today in the mail I received: a K-41 escape tower 3d printed in white plastic. I worked with Michael Key at Shapeways to modify (via scaling) an escape tower he already produced for a plastic kit. Unfortunately, it was not perfect in that the top of the rocket motor and the aerospike did not make it. That is being checked on right now.

Over the next few days I'm going to work on fitting it to the balsa cone. The tower includes the cone-shaped antenna section cover so that will have to be sanded off the capsule. Also, I will learn and share finishing methods for the tower as it does have the characteristic 3d-printed rough surface. I'll tweek it and give feedback to the designer. I'm also going to check it against my Weeks drawings. I used scale of the kit as 70" Redstone/ 1.637 BT-60 = 1/42.76 scale.

This should fit the BT-60 Dr. Zooch Mercury capsule as well.


I also ordered an 1/100 Apollo tower to replace the missing one on my Centuri Saturn 1b. Its molded in translucent plastic and is not as rough as the white plastic. I'll mess with it after I get the Mercury sorted out.

[dlazarus6660]

Mark,

Nice job. Anything more on this project. Can you set me up with an LES for my MR? :rolleyes:

[MarkB.]

Actually, yes, there is more on this project:

I mentioned I ordered a 3D printed escape tower from Shapeways. There were problems. As noted, the top of the escape rocket was missing. Also, as I compared it to my plans (David Weeks drawings), I noted that the lower diagonal and the cap were not properly positioned with the lower diagonal attaching below the cap. I cut these parts off and switched their positions using JB Weld and some Evergreen round styrene to replace the trimmed-off diagonal. It looks much better now. Other problems include a missing conduit to the escape rocket and the mounting hole being slightly too large.

I received the replacement top of the escape rocket in the mail today.

I've also worked with the designer to correct the problems and to reduce the price. I should receive v.2 in the mail in a few days. I will test fit it to the K-41 capsule and to a Dr. Zooch capsule and if I get really lucky, and can find it in my parts box, to the Semroc BT-60 capsule as well. All of these are balsa 1/42.7 scale for BT-60.

I will post pictures when the new tower comes in. And it will absolutely be launched, maybe by Yuri's Night.


Now, Dlazarus' picture shows a later Centuri/Estes Mercury capsule at 1/35 scale. I haven't worked on that one yet, but that may be a future project. Shapeways does have some significantly more accurate, larger Mercury towers and capsules available but they are pretty darn expensive. If I run across one, I'll post a link.

[Kidagain]

You can bye a new Capsule and LES from Estes #1921 Mercury/Redstone now for BT-70

http://www.estesrockets.com/034125-mercury-redstone-capsule-plastic-parts

[MarkB.]

Actually, its NOT BT-70. Its the old Centuri/Semroc ST-20 tube.

[ghrocketman]

Once built, I 'painted' my K-41 MR tower with 30-minute epoxy thinned 50/50 with Acetone.
The thinned epoxy soaks into tne wood and really strengthens it.

[MarkB.]

And that's exactly what I'm going to do with the 3D printed tower.

Pictures this weekend.

[Kidagain]

I built mine using carbon fiber rods. Used Medium CA to bond. Its bullet proof. Also built the SEMROC Little Joe II in same manner. | can squeeze the hell out of the tower and its solid!!

[mojo1986]

I built mine using carbon fiber rods. Used Medium CA to bond. Its bullet proof. Also built the SEMROC Little Joe II in same manner. | can squeeze the hell out of the tower and its solid!!

Wow, you must have been doing something right! I built one from carbon fibre rod and used CA to bond it, but I felt that adhesion of the glue was poor. I don't trust the tower at all and have never had the nerve to launch.

Joe

[Kidagain]

I recommend using medium CA, not thin for building the tower. It will be very strong. I did not use an accelerator.

[MarkB.]

Alrighty guys,

Attached are pictures (one with flash and one without) of the 3D printed towers on both the K-41 capsule AND the Dr. Zooch capsule. They are made of PVC-like material that is surprisingly tough. Typical of 3d printing, they are rough to the touch. As I indicated above, I'm going to "paint" them with finishing resin which will both smooth them out and add strength. Recall that the K-41 capsule is to be rigged to parachute suspended horizontally. There's no way the aerospike would survive a point-down landing.

Yes, I know this is going slowly. . . .


I didn't get a Yuri's Day or a Big Al Cinco de Mayo launch because the weather's been so crappy. So I'm shooting for a Memorial Day launch, with K-41 to take to the skys after 41 years.


I'll post more pictures in coming days. I've got some Rescue Sandhawk pictures, too.

[ghrocketman]

Looking good, Mark !

[Kidagain]

Wow, you must have been doing something right! I built one from carbon fibre rod and used CA to bond it, but I felt that adhesion of the glue was poor. I don't trust the tower at all and have never had the nerve to launch.

Joe


Joe I need to correct my statement. I said the exact opposite of what I meant as I became confused what I did and realize after working with some more carbon rods I got it wrong. I use thin CA with micro-bubbles. It creates more surface area for the CA to take ahold of. Just use a tiny bit of the micro-bubbles to cover the joint or you will spend time sanding off the oversized knuckle. That is what I did in the first few. It had been awhile. I recently started working on a new tower for a new Mercury/Redstone using this method.

[Kidagain]

Alrighty guys,

Attached are pictures (one with flash and one without) of the 3D printed towers on both the K-41 capsule AND the Dr. Zooch capsule. They are made of PVC-like material that is surprisingly tough. Typical of 3d printing, they are rough to the touch. As I indicated above, I'm going to "paint" them with finishing resin which will both smooth them out and add strength. Recall that the K-41 capsule is to be rigged to parachute suspended horizontally. There's no way the aerospike would survive a point-down landing.

Yes, I know this is going slowly. . . .


I didn't get a Yuri's Day or a Big Al Cinco de Mayo launch because the weather's been so crappy. So I'm shooting for a Memorial Day launch, with K-41 to take to the skys after 41 years.


I'll post more pictures in coming days. I've got some Rescue Sandhawk pictures, too.

Fantastic Mark,

I presume this for the BT-60 Model.

Making them available for purchase could make you popular! ;)

[MarkB.]

OK,

Here's the link: http://www.shapeways.com/product/YYSA3RH83/mercury-les-tower-estes-1-42-7?optionId=58511353

I worked with Michael on both the accuracy and the price (it was orignially $42.00). It will work on both Dr. Zooch and original Estes K-41 BT-60 based Mercury Redstone. The only mod to the Estes kit is to cut or sand off the tip of the nose cone as that is included on the tower.

And you should look around the Shapeways site. Type in "Estes" or "Rocket" and look around. You will be absolutely amazed at what you'll find. I have the nuclear nose for an ST-20 Redstone on the way. Some of the stuff is a little over-priced, but I found if you contact the designer, you might work something out.


I do hope this makes me popular. But wait, I already married the cheerleader captain, what else do I get? Actually, I'd just love to see pictures of K-41s returning to flight with these towers. THAT would be great!

[Kidagain]

OK,

Here's the link: http://www.shapeways.com/product/YYSA3RH83/mercury-les-tower-estes-1-42-7?optionId=58511353

I worked with Michael on both the accuracy and the price (it was orignially $42.00). It will work on both Dr. Zooch and original Estes K-41 BT-60 based Mercury Redstone. The only mod to the Estes kit is to cut or sand off the tip of the nose cone as that is included on the tower.

And you should look around the Shapeways site. Type in "Estes" or "Rocket" and look around. You will be absolutely amazed at what you'll find. I have the nuclear nose for an ST-20 Redstone on the way. Some of the stuff is a little over-priced, but I found if you contact the designer, you might work something out.


I do hope this makes me popular. But wait, I already married the cheerleader captain, what else do I get? Actually, I'd just love to see pictures of K-41s returning to flight with these towers. THAT would be great!


Yep I am aware of his site. I bought the Bt-60 Tail section for the Redstone and have my eyes on a few other goodies he makes. Some of his items are pricey, but that is the cost of limited runs and one off parts that take lots of time to design and make prototypes.

[MarkB.]

TaaDaa!

Well, it took a while (like, 40 years), but I have my K-41 Mercury-Redstone ready for launch. I stayed up last night assembling parachutes. I replaced the sticky dots with new ones and the shroud lines with new from Semroc, just to be safe. The pictures show the rocket in this morning's blue Texas sky with a close up of the capsule and the 3d printed tower.

A word on the tower: Finishing the tower, I used 30 minute epoxy to coat the entire tower. The epoxy filed the rough print grain perfectly and added considerably to the overall strength. I recommend that you do the epoxy in two parts: do the base and legs in one session and the nozzles and motor in a second session, going slowly to allow you to minimize the runs and drips while the epoxy drys. Don't ask me how I know. Paint was Rustoleum grey filler primer under good, old Testors Flat Red 1230 spray. The cap and ring were hand painted with Testors flat black. Everything, including the paper wraps, got a coat of Rustoleum clear Matte.

[mojo1986]

That looks REALLY excellent!

Joe

[ghrocketman]

VERY Nice, Mark !
One of these days I'm going to have to build one of my three K-41 kits.
I built one way back in like 1981.
That kit with it's PIA tower, the K-29 1/70 Saturn 1B with wood tower, and original Estes Little Joe II are the ONLY kits I have built that rate a legitimate "Skill Level 5".
The Estes Saturn V and Mars Lander are not even close as difficult as those towers.
The new Estes kits that have a level 5 rating are a joke compared to the fins/tower on the K-41.
In my opinion, the K-41 MR is the most difficult to build LPR rocket ever kitted.