Rich's T300 Nike Smoke

My next project (running concurrently with several other rockets) is a scale/sport scale of the Nike Smoke sounding rocket. The airframe is BMS T300 and the motor mount is BMS T52H tubing, with custom rings and fins by myself. Nose cone is one I picked up from a member of TRF a while back and is a Estes PSII Nike Smoke nose cone, while I could turn one from wood myself (that's my planned Nike Wood Smoke project). The design will include a chute shelf/shock cord anchor point and a nosecone Altimeter bay for electronic deployment.

First up is the fins,

Left Photo: Fin cores getting prepped for skins each core averages about 16.9g without the basswood or balsa parts, just the 1/8" Baltic Birch Plywood (I buy it in 5' by 5' sheets from my local wood wholesaler). The holes lighten the fins by about a third and without much loss in strength. Strength really shouldn't be much of an issue as this rocket should be able to fly on about any commercial 29mm motor that will fit in the pipe, and its being built to handle the longest ones from both Cesaroni and AT.

Center Photo: Center balsa skins and basswood ribs installed, one fin has outer triangular skins installed as well.

Right Photo: The pressure is on the fins are stacked in pairs with wax paper between them and the books stacked on. The technical drawing book I have had for nearly 30 years as it was the very same one I studied drafting with in high school, the other drawing book is the one I used in college 27 years ago. Still struggling my way through Solidworks, and have yet to learn AutoCad though AutoCad was taught to us as an intro module in high school using a Apple IIe (iirc) and a digitizer pad with pen. In a couple of hours I will pull the books off and then tomorrow start profiling the fins.



My technique for multi faceted fins is to use harder woods like basswood for ribs then sand for example profile of the center of the fin with the taper from root to tip, the basswood being harder than the balsa but softer than the plywood allows the sanding to not cut to much into the core material. The once the root to tip taper is complete the triangular pieces tapers from fin center to leading and trailing edges along the root edge will be sanded. After the basswood is properly profiled the balsa is easy to get sanded to the correct profile. For me its a simple way to get nice even fin tapers on fins like the Nike Smoke and my Nike Hercules 2 stage.

Fins are ready for installation. Cores are assembled, fins profiled and papered. The majority of the profiling was done carefully on a 4" belt/6" disc Ryobi belt sander my wife bought me for Christmas two years ago (yes she asked before buying me tools as I am notoriously picky about quality, this was my exception quality-wise). Finish profiling was done with 150 grit sandpaper and a 11" Great Planes Easy Touch Bar Sander (it has seriously worn 220 stuck to it currently thats more like 220). The paper skins are FedEx half sheet shipping labels and darn if they aren't sticky. Fins were weighed at each step of the process for comparison.

Fin # ---Core Only /--- Core with Balsa Skins/ After Profiling / Profiled Fins with Paper Skins

Fin 1 ---17.4g---------- 28.6g-------------------- 22.3g---------- 23.6g
Fin 2--- 16.8g---------- 29.0g-------------------- 22.7g-----------24.1g
Fin 3--- 16.6g---------- 28.6g-------------------- 21.7g---------- 23.2g
Fin 4--- 16.8g---------- 28.1g-------------------- 22.3g---------- 24.1g

Last Photo: is MMT (29mm), centering rings of 1/8" Baltic Birch, and recovery anchor plate/ chute shelf.

Nose cone work today, by the numbers...

Pic 1: inner CR for nose cone altimeter bay installed, the ring is set in the 1/8" band just below the smoke exit covers on the PSII nosecone, as its a snug fit it almost self locks into the ring in the nosecone. The ring was epoxied in last night.

Pic 2: Completed nosecone altimeter bay (pic got out of order).

Pic 3: Second altimeter bay ring with match drilled holes for threaded inserts (they still need to be opened to final diameter for the inserts), epoxied in place with BSI 15min epoxy with US Composites milled FG mixed in, due to its quicker gel time the epoxy was almost perfect viscosity to self form a fillet then set.

Pic 4: Second ring and inner tube (BT70H) with nosecone. The small diameter holes visible in the ring is where I use brad nails to hold the ring to a 12-18" scrap of 2x4 stud so my hands are clear of the flycutter, the brads also seem to help keep the thinner rings (ID to OD thickness) from breaking as easily, to remove the brads without breaking the centering ring I use a small "super/wonder bar" type prybar (about 8" long) and pliers to remove the brads which are not completely nailed flush. Laying the prybars nailhole over the ring and pulling the nail with the pliers keeps the ring from flexing and breaking.

Pic 5: Inner tube for altimeter bay the self adhesive label paper build up is due to slightly over size rings (I used a flycutter set for 54mm to cut out for the BT70H and it was just about 1/32" large).

Pic 6: Sled ready to fly with Eggtimer Quantum and Turnigy 300mah 2s LiPo from HobbyKing, this sled is actually used in my Nike-Cajun 2 stage as well.

Pic 7: Other side of sled, as configured the sled, all thread and fasteners weight about 83g (2.95ozs) which also acts as nose weight if needed (according to the sims even a CTI I243 needs no additional nose weight). I have quite a few short delay AT 29mm motors now that I pick up on clearances because most people are looking for the longer delays, and I prefer electronic ejection initiation whenever possible (no AT bonus delays).

Pic 8: Ematch wire bulkhead pass-through hole, the wire lays in a small notch on the side of the hole nearest the ejection charge canister.

Pic 9: a better view of the wire slot in the pass through.

Pic 10: Bulkhead installed and well-nut/expansion nut (they are actually called Rawl Nuts) installed with wire, once tighten the altimeter bay is airtight. Speaking of which I still need static ports on the nose cone, I was thinking of making them part of the smoke exit cover detail.



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Fins are on!

Pic 1: Forward CR and MMT installed, there is a 2" section of airframe coupler in front of the forward CR to help keep ring square to airframe axis, the rear centering ring was used to keep the MMT centered at aft end temporarily (usual 2 screws in CR so you can pull it out later method, not shown).

Pic 2: Payload Bay Fin Guides are great when dealing with oddball tapered fins, the fins are just under 1/8" at the tip, and about .315" at the root to airframe junction (tabs are 1/8" thick)

Pic 3: Rear CR installed (pre-fillet).

Pic 4: Recovery Anchor and Chute shelf ready to install, made of 1/4" baltic birch with four .375" and four .25" holes for ejection gases. I have been using this style bulkhead on single deploy rockets for about 3 years now and have yet to have one fail, if the rocket has a motor mount that needs long motors then I just use a CR to do the same thing then the motor can pass through it. It also makes changing the short recovery tether easier.

Pic 5, 6, 7: Static Port camouflage, while not scale I think they turned out rather nice. Static Ports are .125" holes (3), the covers are made from Evergreen Plastics .25" OD x .031" ID polystyrene tubing cut on a 45 degree angle and attached with Testors Liquid Cement for Plastics (on polystyrene its almost as quick setting as CA, but allows just a little working time to move the part if necessary).

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Here's my attempt at recreating the Alodine coating on the fins of one of the Nike Smokes. Alodine is a type of Chromate Conversion Coating that at one time was commonly used on magnesium and aluminum, the effect looks like those cheap tools with a gold color that come with assemble yourself furniture.

Pic 1: first step in the attempt to simulate Alodine coating, coat fins with a base of Krylon Short Cuts (aerosol) Chrome

Pic 2-3: next coat fins with a thin coat/mist of Testors Model Master Turn Signal Amber (one photo is inside under Daylight LED flourescents, the other is outside in natural light).

Pics 4-5: another indoor and outdoor comparison of the color after the masking was removed.

Pic 6: nose cone paint finished with the band of OD green around the flange section of the M5E1 motor, the Estes nose cone actually includes the top motor flange of the Nike motor as part of the NC.

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Observations: the gold color might be a bit too gold and it needs a bit of brassy color to it, after decals the model will get coated first with Krylon Crystal Clear gloss (to hide decal edges/backing) then after that cures the whole thing will get a coat of Krylon Matte Finish, to flatten the color scheme back out.

Since I am restricted from doing anything that might get dust in my right eye, due to a grinding incident last Wednesday, night it was painting and cleanup today and yesterday.

Pic 1: part of the reason for my eye issue, the black sliver on the tissue is a piece of steel that came out of my eye about 15-16 hours after I it went in, but that wasn't the end, 4 more hours later and 2 doctors a piece approximately .05mm by .075mm was removed from the cornea while the removal was painless (good anesthetics) the afterwards was painful (the piece removed by the doc was about a 1/4 the size of the one on the tissue). The doctor is not allowing me to return to work until hopefully Tuesday the way its looking now, this is the first time I have ever heard of a "bandage contact" which is how they protect the wound site. Lesson learned is look harder for the damned face shield (I was wearing safety glasses) which was somewhere in the shop. Safety glasses are no substitute for a full face shield when using a bench grinder as the little sliver went right under my glasses.

Pic 2: model coated with Krylon Crystal Clear prior to application of decals, decals are applied in this pic but are very hard to see. The decals are homemade waterslides with yellow lettering and against the OD Green are very difficult to see with the glossy clear coat. When I do the Nike-Nike-Smoke 2-stager I will use the wifes Cricut to create a paint stencil and airbrush the markings.

Pic 3: Decals and model coated with Krylon Matte Finish, decal is more easily visible and readable under natural light.

Pic 4: Pic of mostly finished rocket, just rail-buttons left to go and the motor retainer (cleaned up the rocket shop in my office and found several extra Estes 29mm retainers laying around). The fins Alodine coating actually looks pretty realistic in sunlight, inside it looks really yellow. The flat finish also helped tone down the color. This bird will be ready to fly at the clubs next launch.

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With out motor or recovery (parachute and shockcord) the model currently weighs 609.1g (21.48oz) which is about 1.5oz's heavier than the sim so not bad in my book if it only got 1.5oz's fatter post paint/build, the sim doesn't account for screws and threaded inserts in the nosecone which with the paint probably accounts for all the added mass.

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Nice idea to integrate the static ports into the smoke release covers...and an inspirational revelation for me, as I thought/heard somewhere that static ports should be located clear of inclined surfaces like nosecones to ensure accurate altimeter readings...clearly I've been labouring under an illusion!

Generally it is recommended to have the static ports down on the non tapered portion away from discontinuities. https://www.adeptrocketry.com/staticports.htm
I don't know if there is newer emperical data on nose mounted altimeters now.

burkefj said:

Generally it is recommended to have the static ports down on the non tapered portion away from discontinuities. https://www.adeptrocketry.com/staticports.htm
I don't know if there is newer emperical data on nose mounted altimeters now.

Click to expand...

Very true however in the case of nosecone altimeter bays especially with short shouldered plastic nose cone they get put wherever seems good. A number of rockets that I have and fly regularly have these type bays, the ejection is normal at apogee, but the data plot is definitely "noisier" than if the static ports were further away from the transition area. FG rockets with FWFG nose cones are much easier as the longer shoulders allow the ports to be put about 1 calibre below the nosecone airframe transition.

Right, so that is some empiracle evidence, again, not necessarily recommended but if you have experience and it works that's great. When you say in fwfg long shoulders allow the ports to be put 1 caliber below the nose cone, you are then relying on the ports lining up with holes in the body tube I assume and that they won't rotate under any spin etc to block them off, or you have a shear pin to locate them correctly? I worry a bit about a nike altimeter bay only one caliber below the cone shoulder since there is a definite transition/turbulent air there.

Frank

rharshberger said:

Very true however in the case of nosecone altimeter bays especially with short shouldered plastic nose cone they get put wherever seems good. A number of rockets that I have and fly regularly have these type bays, the ejection is normal at apogee, but the data plot is definitely "noisier" than if the static ports were further away from the transition area. FG rockets with FWFG nose cones are much easier as the longer shoulders allow the ports to be put about 1 calibre below the nosecone airframe transition.

Click to expand...

burkefj said:

Right, so that is some empiracle evidence, again, not necessarily recommended but if you have experience and it works that's great. When you say in fwfg long shoulders allow the ports to be put 1 caliber below the nose cone, you are then relying on the ports lining up with holes in the body tube I assume and that they won't rotate under any spin etc to block them off, or you have a shear pin to locate them correctly? I worry a bit about a nike altimeter bay only one caliber below the cone shoulder since there is a definite transition/turbulent air there.

Frank

Click to expand...

I would definitely concur on a Nike bay static ports with only 1 caliber below the shoulder, that nosecone transition is huge and may disrupt the airflow for further than the 4 calibres that Adept Rocketry mentions. Yes to the lining up holes in the airframe and coupler for FWFG nose cones, so far I have only built one rocket that way ( 38mm Mini-Frenzy) and it uses 6 holes around the NC coupler and airframe, 3 for shear pins and 3 for static ports regrettably the JL3 that was riding in the NC bay on the first launch was destroyed by an off nominal ejection event (caused by the piston, I think) even though the rocket was recovered safe. This rocket will fly with a recording altimeter, but in my others I usually just fly them with a max altitude reporting one like a Eggtimer Quark since the data is noisy, however now that I have a new JL3 it can ride along in the parachute burrito and hopefully give me a better comparison to whats really going on with the NC bay and how accurate the recorded altitude is (static ports will be about the mid body length of the airframe).

Interesting discussion. So it would seem 'noisier' altimeter readings don't necessarily increase the likelihood of an early ejection charge firing..?

Tim51 said:

Interesting discussion. So it would seem 'noisier' altimeter readings don't necessarily increase the likelihood of an early ejection charge firing..?

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My experience has shown apogee ejection to be normal, which probably is due to the airspeed being near zero ( or as close as its going to get).

rharshberger said:

My experience has shown apogee ejection to be normal, which probably is due to the airspeed being near zero ( or as close as its going to get).

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Thanks - that's good to know.

Did a bit more on the project today but no pictures yet. Applied flat white color coat to nose cone as part of first step on NC paint, the second step will involve masking the nose cone near the base and spraying with OD Green to match the top of the M5E1 motor section. The main airframe was masked off from about 1/8" in front of fins to rear of rocket so forward section could be painted OD Green. My color scheme is the same as the one pictured below, which I believe is the same one MUGS914 did not too long ago. From what I can tell the fins are not painted but they do have what appears to be a Cadmium Chromate Conversion treatment giving them the goldish color which I am going to attempt to re-create using a two step painting process, first is to paint the fin section silver then hit it will a very light coat of Testors Model Master Turn Signal Amber (using an airbrush). The graphics for the motor are already done, but I need to find a copy of the US Vintage No. 72 True Type Font to have authentic style lettering, the graphics are based off the yellow ones seen on most M5E1 motors that give firing and storage temps, lot no, model number, drawing ref etc. as I believe that would be how this round would be labeled, since it looks like they just removed it from the shipping crate, added the fins and nose cone then flew it.




After doing a bit of research from the Nike Fins PDF, the modified diamond fins (which is the ones the Nike Smoke uses) are made from a hollow cast magnesium metal, the coating therefore is most likely Alodine (a type of chromate conversion coating) and hence would have a golden color to them.

Updated the build thread with paint photos, for comparison post #18 is the round I am trying to model.

https://www.rocketryforum.com/showthread.php?145354-Rich-s-T300-Nike-Smoke&p=1775541#post1775541

Updated the build progress.