BMS Astron Drifter

[JAL3]

The Atron Drifter is an old line Estes kit that Balsa Machining produces a kit for. The kit comes with materials except for parachute and decals. I got a set of the classic decals from Excelsior. The kit is also sold without plans but a web address if given to download them here: https://www.spacemodeling.org/JimZ/estes/k-14.pdf

I'm breaking my own rule about having too many projects going at once because, once again, I find the other projects waiting for things outside of my control. :bangpan:

 

[JAL3]

The first step in construction is to locate the coupler tube and the ring(s) intended to be fitted to the end. I was a little fuzzy about this because the context of the downloaded instructions implied that there would be 2. THe kit only had a single one and I can imagine how that might work. I fired off a question to BMS, glued the one ring in place and turned my attention to other aspects of the build.

 

[JAL3]

The motor mount itself was simple enough. A thrust ring was glued into the end of the motor tube.

 

[JAL3]

The nose cone was a nicely turned piece of balsa but here there was a slight deviation from the instructions. The instructions indicate that the eye screw needs to tap its own hole for mounting. In reality, the centerline of the nose cone was already drilled to a significant depth in a diamter much greater than that of the screw threads. This seemed fairly inconsequential to me and I filled the hole with a surprising amount of yellow glue (it was DEEP) and then inserted the screw.

 

[JAL3]

One of the features of this rocket is a boattail design. The boattail is formed from a rolled piece of paper with the outline marked upon it. The boattail, a wrap around fin guide and a fin template were all part of the package.

The boattail was cut out, curled around the dull edge of some shears and glued together with a hint of white glue. It was test fitted on the motor tube and the fit was satisfactory.

 

[chanstevens]

The nose cone was a nicely turned piece of balsa but here there was a slight deviation from the instructions. The instructions indicate that the eye screw needs to tap its own hole for mounting. In reality, the centerline of the nose cone was already drilled to a significant depth in a diamter much greater than that of the screw threads. This seemed fairly inconsequential to me and I filled the hole with a surprising amount of yellow glue (it was DEEP) and then inserted the screw.

I think you overlooked one big feature of nose cones turned on Bill's newer lathe--they have large holes in them, into which you're supposed to insert a sort of ribbed dowel pin. The ribbed dowel pin is pre-drilled for screw eye. I would imagine your big glob of glue solution would work OK, though take quite a while to set, but at least now you'll know what to do with that funny looking little round thing left over when you're done .

 

[JAL3]

I think you overlooked one big feature of nose cones turned on Bill's newer lathe--they have large holes in them, into which you're supposed to insert a sort of ribbed dowel pin. The ribbed dowel pin is pre-drilled for screw eye. I would imagine your big glob of glue solution would work OK, though take quite a while to set, but at least now you'll know what to do with that funny looking little round thing left over when you're done .

That makes sense and I already wondered about the dowel. I saw it and didn't see it mentioned in the instructions.

I'll take a closer look at the "face card" and see if it is mentioned. I just glanced at that, saw the inventory and the templates and did not notice anything else, figuring that the instructions downloaded from jimz would be correct.

 

[chanstevens]

It's certainly not going to show up on the Estes/Jim Z plans, and I doubt very much if there's even a reference to it in anything from the BMS parts list. It literally depends on which lathe the nose cone is turned on--BMS bought a new lathe a couple years ago that enables Bill to run much higher volume, and it's the cones run on that lathe that get the dowel. You can buy a standard nose cone one month and see solid shoulder, then buy the same cone a month later and find it drilled for a dowel. It just depends on how it was run. Odd that your dowel was loose, though--Im not certain, but seem to think most of the drilled noses I've gotten have either had the dowel inserted already or shipped with it tucked in same baggie as the nose.

 

[chanstevens]

P.S.--most of us consider the drilled nose+dowel to be a mjor improvement over solid shoulder nose cones. The screw eye bites much stronger to the hardwood dowel, and the dowel itself provides much greater surface area for gluing inside the nose. End result is a great anchor that just won't fail, compared to the (admittedly infrequent) failure mode of pulling a screw eye out of weak balsa.

 

[JAL3]

It's certainly not going to show up on the Estes/Jim Z plans, and I doubt very much if there's even a reference to it in anything from the BMS parts list. It literally depends on which lathe the nose cone is turned on--BMS bought a new lathe a couple years ago that enables Bill to run much higher volume, and it's the cones run on that lathe that get the dowel. You can buy a standard nose cone one month and see solid shoulder, then buy the same cone a month later and find it drilled for a dowel. It just depends on how it was run. Odd that your dowel was loose, though--Im not certain, but seem to think most of the drilled noses I've gotten have either had the dowel inserted already or shipped with it tucked in same baggie as the nose.

That makes sense.

I had assumed that the kit was an "exact" clone and that there would be no deviations. No harm done and what I have certainly seems to be of good quality.

 

[JAL3]

P.S.--most of us consider the drilled nose+dowel to be a mjor improvement over solid shoulder nose cones. The screw eye bites much stronger to the hardwood dowel, and the dowel itself provides much greater surface area for gluing inside the nose. End result is a great anchor that just won't fail, compared to the (admittedly infrequent) failure mode of pulling a screw eye out of weak balsa.

That makes sense as well. I'll be on the lookout for it the next time I open up a BMS kit. I know there are a few sitting around.

 

[Handeman]

The Drifter is still one of my favorites. Back in the day, I build a Scout as part of a Cub Scout activity, the Alpha that came in my starter set, and the first rocket I bought with my own money was the Drifter.

The Drifter was a duration contest rocket that came with both a 12" and 24" parachutes. I only flew mine with the 24" chute and a C6-7 one time. I thought it was a perfectly calm day. I got it back over a mile away and after a 15+ minute flight.

I also bought the BMS kit and recreated that Drifter from way back. I have flown it with a C6-7 again, but only with a 12" chute. It was one of those very rare and very calm days and landed only 300 yards from the pad.

 

[JAL3]

The Drifter is still one of my favorites. Back in the day, I build a Scout as part of a Cub Scout activity, the Alpha that came in my starter set, and the first rocket I bought with my own money was the Drifter.

The Drifter was a duration contest rocket that came with both a 12" and 24" parachutes. I only flew mine with the 24" chute and a C6-7 one time. I thought it was a perfectly calm day. I got it back over a mile away and after a 15+ minute flight.

I also bought the BMS kit and recreated that Drifter from way back. I have flown it with a C6-7 again, but only with a 12" chute. It was one of those very rare and very calm days and landed only 300 yards from the pad.

I thought I remembered something about it being a competition model.

I will probably put a streamer in it just because I prefer them in small rockets like this. Competition is not really an issue with me.

 

[jflis]

I thought I remembered something about it being a competition model.

I will probably put a streamer in it just because I prefer them in small rockets like this. Competition is not really an issue with me.

Caution here... One of the design features of the Drifter is incredibly thin fins that taper WAY back below the motor. If you want to use streamer recovery I suggest that you beef up the fins with either paper laminates or go with a thicker fin stock...

 

[JAL3]

Caution here... One of the design features of the Drifter is incredibly thin fins that taper WAY back below the motor. If you want to use streamer recovery I suggest that you beef up the fins with either paper laminates or go with a thicker fin stock...

Point well taken.

I can't say I had given it any thought on this rocket but most of my recent efforts have used paper label lamination. I'll probably do that on this one too although the shape of the fins makes that a more problematical.

 

[JAL3]

On recent builds with balsa nose cones I have gotten into the habit of hardening the balsa with CA. I did that on this rocket as well using thin CA drizzled over the cone. When dry, I sanded and added another coating after which I sanded again.

 

[JAL3]

BMS responded quickly to my inquiry and it turned out that indeed 2 centering rings were intended for this rocket. They mailed out a replacement, plus a spare, and got it to my quickly. With the ring in my posesion, I was able to glue it in place on the opposite end of the coupler tube as the first one.

 

[JAL3]

The Astron Drifter is supposed to use an Estes style trifold shock cord mount. Since I detest these, I instead cut a notch in each of the centering rings large enough to pass a Kevlar thread. I then passed the Kevlar through the notches and slipped the coupler tube in place over the motor mount. The Kevlar was then tied around the motor tube and filleted into place with yellow glue.

 

[JAL3]

The boattail was then slid into place against the rear of the motor mount and secured with some white glue.

 

[JAL3]

When the glue on the boattail was dry, some more was placed in the aft end of the body tube and the motor mount was shoved into place.

 

[JAL3]

I left the body tube/motor mount/boattail assembly to dry overnight and ran into a problem. Little 6 year old hands decided to investigate some of the mysteries of what I do in the garage sometimes and apparently considered to boat tail to be a real touch and feel exhibit while the glue was still setting up. The result was a pretty wrinkled boat tail. I could have and should have made another one but laziness and the heat in the garage were working against me and I decided to just go with it.

 

[JAL3]

The next actual construction step was to locate the wrap around fin marking guide. I had two of them. One was included in the kit and one was printed out with the instructions downloaded from Jimz. They were identical and I cut one out and taped it into place so that one of the fin lines was aligned with the boattail seam. I then transferred the fin marks to the body tube.

 

[JAL3]

The fins were of nice material and practically jumped out of the parent stock. I expended a minimal amount of effort in rounding the leading and trailing edges and pronounced myself satisfied.

 

[JAL3]

The fins were placed using yellow glue and the double joint method. They went in place so that the back of the root edge was at the bottom of the boat tail.

 

[JAL3]

The fins were placed using yellow glue and the double joint method. They went in place so that the back of the root edge was at the bottom of the boat tail. When the glue joints on the fins had dried, I began to apply white glue fillets. It was about at this point that I realized that I ahd forgotten my intention to "seal" the fins with label material. I wanted to do this to ease the finishing process and because I intended to used a streamer instead of a parachute and had been warned that the swept back fins would be prone to breakage.

 

[JAL3]

Some sewing elastic was tied to the nosecone and the Kevlar and I thought construction had been completed until I glanced at the bag and found the launch lug.

 

[JAL3]

The lug was glued along one of the fin root edges with white glue and then construction really was done.

 

[JAL3]

As I mentioned before, I had intended to use label paper to seal the fins but forgot until too late. Since this project was never going to win any beauty contests and I was not planning on any competitions, I decided to try another experiment which had gone alright on some balsa nose cones. I drizzled thin CA all over the fins to try to do some filling and to give them some strength. When it was dry, I sanded it down. It was not perfect but, considering the boat tail, it would do.

 

[JAL3]

The Drifter was taken to the booth and given 2 coats of Kilz primer.

 

[JAL3]

After a day, the Kilz was sanded down. It seemed that the combination of CA and Kilz had done an adequate, but not great, job of filling the balsa.

The rocket was then dusted off and placed in the booth. It was given 2 coats of metallic hammered silver. Not a great deal of attention was paid to the fins since they would be painted another color.