Formula 98 Lemon Yellow Build Thread

Welcome to the first post of my Formula 98 build thread. This rocket is a 4 inch, 54mm motor mount, G12 colored fiberglass rocket from Rocketry Warehouse. This rocket was selected for a few reasons. My previous high power rocket was a 38mm, and I wanted to move up to 54mm after recently getting my Level 2. I also wanted a durable fiberglass rocket to use as a workhouse. There are lighter rockets than the Formula series, but Formulas seem to be extremely durable and easy to put together. I have never worked with fiberglass before and I think the Formula series is good for a first fiberglass build. This rocket will be using a MARSA54 for the primary altimeter with a PerfectFlite StratoLogger for backup. I also plan on making a fixed camera mount for my Replay XD1080 as well. I may experiment with adding radio tracking a bit later when I start flying with larger engines higher and farther. Without further ado, here's what I'm sure you all came here for, pictures. These were taken using my cell phone camera under artificial light, so the color and saturation may be slightly off.

Picture 1: Overview of all parts included in kit


Picture 2:Closeup showing fins and nosecone


Picture 3:Closeup of filament wound airframe showing filament pattern and coloring


Picture 4:Closeup of cast graphite nosecone tip

I have been thinking about getting one of these (the 150 I believe) in 75 or 98mm

Subscribed! This is a great rocket for Level 2 that is why I am planning on attempting mine with a F98. Would like to see how you arrange your e-bay.

DM1975 said:

I have been thinking about getting one of these (the 150 I believe) in 75 or 98mm

Click to expand...

I had considered getting the 150 myself. If I can figure out how to get a 30" motor into a 36" airframe, whiled accepting 6" of coupler, then I would be sold.

You could request a longer booster tube. You could also design a boat tail on the back of the rocket.

DRAGON64 said:

I had considered getting the 150 myself. If I can figure out how to get a 30" motor into a 36" airframe, whiled accepting 6" of coupler, then I would be sold.

Click to expand...

DRAGON64 said:

I had considered getting the 150 myself. If I can figure out how to get a 30" motor into a 36" airframe, whiled accepting 6" of coupler, then I would be sold.

Click to expand...

This problem was solved in an elegant way by the designers of the Gizmo XL:
https://www.rocketryforum.com/showthread.php?36176

Reinhard

DRAGON64 said:

I had considered getting the 150 myself. If I can figure out how to get a 30" motor into a 36" airframe, whiled accepting 6" of coupler, then I would be sold.

Click to expand...

This is how I am going to do it. I leaves at least 4 inches of avionics bay depth for altimeters, batteries, etc.

DM1975 said:

I have been thinking about getting one of these (the 150 I believe) in 75 or 98mm

Click to expand...

They're great kits, can't recommend them highly enough. Spoke to the owner over the phone and he loves rockets and talking about rockets as much as any of us. Full of great ideas and they're willing to take a few special requests too, within reason. Stuff like longer tubes, different sized mounts, subbing a different nosecone, etc. I love these rocketry companies because of their flexibility and customer service, small individual owned and run business. Try calling up Schwinn bicycles and telling them you love that bike you saw in the store but want slightly different wheels on it.

jus_rockets said:

Subscribed! This is a great rocket for Level 2 that is why I am planning on attempting mine with a F98. Would like to see how you arrange your e-bay.

Click to expand...

I just finished my level 2, used my Madcow Super DX3 converted to dual deploy. The Formula 98 could easy do both 1 and 2. It does seem like it will go together pretty nice. I have some ideas for the e-bay. It may be subject a few revision changes. I bought a 12"x12" sheet of G10 from Rocketry Warehouse. I have the good fortune of access to a PCB CNC machine at work, one from LPKF. So I plan on making it on that. I just want to get it flying at first, but then I want to add a radio link for the serial telemetry from the MARSA54 to receive on the ground. That will probably require a different e-bay layout as I don't know how I'm going to do the radio yet. Good luck on your Level 2.

DRAGON64 said:

I had considered getting the 150 myself. If I can figure out how to get a 30" motor into a 36" airframe, whiled accepting 6" of coupler, then I would be sold.

Click to expand...

patelldp said:

You could request a longer booster tube. You could also design a boat tail on the back of the rocket.

Click to expand...

Indeed, give them a call. The owner was pretty accommodating when I spoke to him.

Threemorewishes said:

This is how I am going to do it. I leaves at least 4 inches of avionics bay depth for altimeters, batteries, etc.

Click to expand...

Good god man. Rather than explain to us where your motor is, it would be a shorter discussion to just tell us where it isn't! That's pretty cool though. Love to see that go up. and up and up and up.

I checked the dimensions with my digital calipers, and man they're close for hobby level stuff. Especially for the prices that this tubing/kits goes for. Within .005 inches of spec'd sizes. But anything that was off ideal was always off on the tight fit side. NO measured dimension is on the loose fit side of the tolerance. The owner said this was done on purpose over the phone when I asked about it to ensure sand to fit for proper tightness.

I also sanded the edges of the tube down, had a few loose glass fibers and rough edges, nothing major, just knocked it down with some course grit a few times and medium and fine to smooth the end out. The motor tube end was sanded down to fit the Aeropac retainer. The centering rings sanded down for the airframe and motor tube fit.

I plan on working on the nosecone and coupler install first. I may stick around my place of work after quitting time to use the machine shop. Of course, pictures will be taken. I plan on using PEM nuts and screws to make the nosecone shoulder/coupler and bulkhead removable for the addition of electronics there at a later date. I first saw this in Dave Lang's Formula 75 build thread here.

I would guess Performance is doing well. Their dealers sell a lot of kits. Plus the kit builders who buy their parts to make kits. I purchased a F150 from Rocketry Warehouse on a Sunday and had the kit by Thursday the same week. Great service. That 6" nose cone is one of the best I have seen.
Thanks RW
GP

Congrats on the new kit, The whole FORMULA Line are all great fliers, I've flown them all.

I look forward to watching this build. I am planning on buying a pair of Formula 54s for my wife and oldest daughter. Also, the 150 could be in my future within the next year or so.

GaryT said:

Congrats on the new kit, The whole FORMULA Line are all great fliers, I've flown them all.

Click to expand...

Disaster_Guy said:

I look forward to watching this build. I am planning on buying a pair of Formula 54s for my wife and oldest daughter. Also, the 150 could be in my future within the next year or so.

Click to expand...

Thanks guys. Yeh, I keep looking over my shoulder and I all I see is the Formula 150 with a big number 3 on it following me around....

So first thing to do is figure out the PEM nuts for holding the nosecone coupler on. This is something I did previously after speaking with Dave Lang for suggestions. So I choose McMaster Carr product number 94648A320 for this, PEM part number KFS2-440. These are designed for use with fiberglass pcb materials according to PEM, perfect. These are used by drilling a hole and the insert gets press fitted in from the backside. See these pictures.

1-Looking at PEM nut from above (screw head side)


2-Looking at PEM nut from below (screw shank side)


They recommend a .166" hole for this part. According to their catalog a 400 pound installation force is required. Usually a arbor press would be used for this. However in this case the PEM nut is being fitted inside of the coupler tube and airframe. This makes using a press....difficult. Dave gave me the idea to just drill larger until the linear pulling force from a screw threaded into it is enough to seat it. So, these pictures above are from my experiments with this. I used the corner of a sheet of G10 to test. First I started with the recommended .166" size. I then attempted to thread a screw and pull the insert nut into place. As expected, the strain on the screw was too great, and despite my efforts the head stripped. Next up was a #18 (.1695") bit. With a ton of force it managed to seat. The screw head was damaged and it bent the hell out of the flat washer I was using to spread the force out. It worked, but given that this would be done on a curved surface, the outside of the coupler, I was worried about having all that force concentrated on a small surface tangent on the coupler. So the next size up was tried, 11/64" (.171") This felt better. There was still a lot of force required, but it did not damage the screw, and I believe it won't crack or damage the fiberglass. Looking at the drawing of the PEM nut, the knurling extends out to .190" so we still have the knurling digging into the fiber glass with approximately .019" of overlap. When these are installed they will get a light coating of epoxy as well. As ze Germans say, it will be guud en tite.

Why not just use an acorn nut and bolt? Nets the same results but takes a fraction of the time, The NC coupler can also just be epoxied in.

Tube marking time! I decided to go with a printed fin guide from paylodbay.com
I generated one with a body diameter of 4.025 inches and 8 fins. Yes, yes, I can count. It is a 3 fin rocket. However, the nosecone coupler will be held on with 4 countersunk flat 4-40 screws 1 inch up from the edge of the nosecone. So four marks are for the nose cone screws, and screws for the e-bay and payload bay screws. Two nosecone shear pins will be aligned with the fixing screws as well. I can also drill 4 vent holes for the e-bay directly between the screws, so the vent holes are receiving clean air. 1" is far enough in to be strong, but close enough to the edge that the nosecone surface is still pretty parallel to the airframe for the screw head to sit nicely flush.

1-Cut out fin alignment guide (this was 4 fins, I reprinted with 8, didn't bother to to retake the picture)


2-Fin guide taped on. 0.3mm drafting pencil used to draw 8 hash marks on tube


3-Nosecone and coupler installed. Held together with masking tape inside coupler and nosecone.


4-Marking along body tube with 1" aluminum angle


5-Making index mark for nosecone and body tube alignment

6-Marking 1 inch up nosecone for screw location (sorry for the focus)

GaryT said:

Why not just use an acorn nut and bolt? Nets the same results but takes a fraction of the time, The NC coupler can also just be epoxied in.

Click to expand...

The nosecone coupler I would like to be removable rather than the bulkhead for adding electronics to in the future. I have a few ideas kicking around for RF equipment, but I'd rather not have to reach in through the coupler to install it.

The acorn nuts are good too, I just like that the PEM nuts bite into the tubing (about .06") . They also are self aligning (assuming the drilling is done ok), sit flatter inside the airframe so as to not present possible hangups for the recovery harness. Rather than having the threading that captivates the screw inside the airframe like an acorn nut does, 0.60" of threading is inside the tube itself, and only 0.70 high sits inside the tube.

It should be made clear that I am still very inexperienced in high power rocketry and am making these decisions not out of wise years of experience, but my whimsy.

With the nosecone marked for the mounting holes for the PEM nuts, I moved over to the drill press. I am using a simple v block fixture called "Center it" acquired from McMaster, product number 20065A8. The idea is a v block that cradles the tube while drilling. The v block is aligned using a large bit lowered into a channel. It is then clamped down. It is then a simple matter of placing the tube on it and lining the tube up with the drill bit. 1/16" pilot holes are drilled with a regular twist bit TiN coated. Then 4-40 clearance holes are drilled in nosecone. All the final diameter drilling is done with brad point made from uncoated solid carbide. These can be seen here, McMaster page 2444. Lastly, 11/64" holes are drilled through the coupler for the PEM nuts.

1-Lining up v block using drill bit


2-Sideview of v block


3-First a 1/16" drill bit is used for pilot holes. It is TiN coated.


4-Closeup of pilot holes. Small amount of splintering inside coupler not shown.


5-Drilling clearance holes in nosecone with #30 brad point carbide bit

6-Drilling 11/16" hole for PEM nuts


The next images show the completed holes. No taping of the backside of the holes was done or backer used. The holes have not been cleaned up at all, these are as they came out of the drill press.

7-Nosecone clearance holes as drilled


8-Closeup of nosecone 4-40 clearance hole


9-Coupler holes as drilled


10-Closeup of coupler holes, can see a small amount of splintering inside hole. Countersink turned a few times by hand should clean up.

patelldp said:

You could request a longer booster tube. You could also design a boat tail on the back of the rocket.

Click to expand...

I believe that a motor retainer will give me the clearance I need. My largest case is a 30.59" (5-grain) and should clear just fine in the current config.

Reinhard said:

This problem was solved in an elegant way by the designers of the Gizmo XL:
https://www.rocketryforum.com/showthread.php?36176

Reinhard

Click to expand...

Interesting build, that thing will take a hulking long motor...

Threemorewishes said:

This is how I am going to do it. I leaves at least 4 inches of avionics bay depth for altimeters, batteries, etc.

Click to expand...

That is one way to make good use of the space you have, thanks for the graphic

kinderwood said:

With the nosecone marked for the mounting holes for the PEM nuts, I moved over to the drill press. I am using a simple v block fixture called "Center it" acquired from McMaster, product number 20065A8. The idea is a v block that cradles the tube while drilling. The v block is aligned using a large bit lowered into a channel. It is then clamped down. It is then a simple matter of placing the tube on it and lining the tube up with the drill bit. 1/16" pilot holes are drilled with a regular twist bit TiN coated. Then 4-40 clearance holes are drilled in nosecone. All the final diameter drilling is done with brad point made from uncoated solid carbide. These can be seen here, McMaster page 2444. Lastly, 11/64" holes are drilled through the coupler for the PEM nuts.

1-Lining up v block using drill bit
[/ATTACH]

2-Sideview of v block
View attachment 94450

3-First a 1/16" drill bit is used for pilot holes. It is TiN coated.
[/ATTACH]

4-Closeup of pilot holes. Small amount of splintering inside coupler not shown.
[/ATTACH]

5-Drilling clearance holes in nosecone with #30 brad point carbide bit
[/ATTACH]

Click to expand...

Love the tube jig you have. I have to use a simple fence design, but I like your alot more. Are they too expensive to purchase? The build is looking great, can't to see it all "dressed to thrill"

DRAGON64 said:

Love the tube jig you have. I have to use a simple fence design, but I like your alot more. Are they too expensive to purchase? The build is looking great, can't to see it all "dressed to thrill"

Click to expand...

Thanks, that was the first time I used it. Worked well, except for the nosecone. Because it is a long tapered shape and I was drilling at the large end, if I took my hand off it tipped off. The couplers and tubing are much easier to work with. It's McMaster part number 20065A8, link here. It's only $17.78 on there. It appears to be extruded in that shape and then every 5" is just chopped off. A pretty cheap way to manufacture.

kinderwood said:

Thanks, that was the first time I used it. Worked well, except for the nosecone. Because it is a long tapered shape and I was drilling at the large end, if I took my hand off it tipped off. The couplers and tubing are much easier to work with. It's McMaster part number 20065A8, link here. It's only $17.78 on there. It appears to be extruded in that shape and then every 5" is just chopped off. A pretty cheap way to manufacture.

Click to expand...

Thanks for that link, I just ordered one for myself.

Did more drill work last night. I put aside the nosecone and nosecone coupler section for now, and worked on the e-bay coupler and payload section mounting. The e-bay section is 8 inches long, and I will be forgoing a switch band. This means that 4" of e-bay will be in the upper payload section and 4" in the booster section. So I will mount the PEM nuts 2 inches from the end of the payload section.

1-Marking 2 inches up using calipers, along same lines as 4 holes in nosecone


2-Using automatic punch set for LOW force to mark holes (did this for nosecone too, forgot pictures), set low or it may crack the fiberglass.


3-Drilled using same technique as nosecone and coupler shoulder. Payload section drilled with #30 for #4 screw clearance hole, coupler drilled with 11/64" for PEM nuts.


4-Cleaning the holes by hand with with an 82 degree countersink. This will be used later to recess the flat screws into the airframe.

I then set to work installing the PEM nuts into the e-bay coupler.

1-A light coating of epoxy was applied inside the coupler. The PEM nut was pressed lightly in by hand, and then a stainless 4-40 machine screw and flat washer was threaded in to pull it into place completely and seat it. Avoid getting epoxy inside the PEM nuts threading if possible during this. The screw was carefully removed, avoid disturbing the PEM nut.


2-A nylon 4-40 screw was coated in 3 in 1 oil, and threaded in relatively tightly. This will clamp the PEM nut down while the epoxy cures, but the epoxy should not stick to the nylon/oil. The is a nice trick I picked up from Dave's thread.


3-This morning I unscrewed the nylon screws and put the e-bay and payload section airframe together using the final 4-40 black flat screws. They are not countersunk yet, so they do protrude. You can see my wife's Minie Magg in the background.


4-Closeup of inside of tubing showing the low profile of the PEM nuts. SO MUCH YELLOW! I love it. I may switch to a slightly shorter screw since they will stick out another 1/16" or so when countersunk.

Gary T
I have used a lot of t-nuts and they work out fine.
GP

crossfire said:

Gary T
I have used a lot of t-nuts and they work out fine.
GP

Click to expand...

Yeh, but what Gary said was true, these inserts do take a lot of steps to install. An acorn nut would be faster. I'm in no hurry though.

crossfire said:

Gary T
I have used a lot of t-nuts and they work out fine.
GP

Click to expand...

Just not my bag baby lol, I'll stick with acorn nuts. To be honest you don't need any nuts here as the Proline Epoxy would be plenty.

kinderwood said:

So first thing to do is figure out the PEM nuts for holding the nosecone coupler on. This is something I did previously after speaking with Dave Lang for suggestions. So I choose McMaster Carr product number 94648A320 for this, PEM part number KFS2-440. These are designed for use with fiberglass pcb materials according to PEM, perfect. These are used by drilling a hole and the insert gets press fitted in from the backside.

Click to expand...

Nice build thread Tom. Lots of attention to detail. I was going to say "Don't get too get too crazy!" but who am I to talk :lol:

Just a note on the PEM nuts. When I fit them, I use a drill size that alows them to be EASILY pressed in using the gentle force of a screw with washer under the head. I don't want the pilot hole too tight for fear of deforming the G12 wound glass which is not nearly as strong as G10 glass. G10 has the benefit of woven cloth layers making it near impossible to split apart. Also a smear of epoxy on the castelated portion of the PEM nut is plenty strong for bonding it in place.

Also I use any kind of PEM nut that is available, not specialized ones, because I do not depend on high insertion forces (and I'm cheap!). I bought a nice assortment of inexpensive PEM nuts from Missile Works for 20 cents each. HERE

Dave

kinderwood said:

With the nosecone marked for the mounting holes for the PEM nuts, I moved over to the drill press. I am using a simple v block fixture called "Center it" acquired from McMaster, product number 20065A8. The idea is a v block that cradles the tube while drilling. The v block is aligned using a large bit lowered into a channel. It is then clamped down. It is then a simple matter of placing the tube on it and lining the tube up with the drill bit. 1/16" pilot holes are drilled with a regular twist bit TiN coated. Then 4-40 clearance holes are drilled in nosecone. All the final diameter drilling is done with brad point made from uncoated solid carbide. These can be seen here, McMaster page 2444. Lastly, 11/64" holes are drilled through the coupler for the PEM nuts.

1-Lining up v block using drill bit
View attachment 94449

2-Sideview of v block
View attachment 94450

3-First a 1/16" drill bit is used for pilot holes. It is TiN coated.
View attachment 94451

4-Closeup of pilot holes. Small amount of splintering inside coupler not shown.
View attachment 94452

5-Drilling clearance holes in nosecone with #30 brad point carbide bit
View attachment 94453

Click to expand...

Great tool find!

I just ordered one online from Eastwood (through Amazon) for $15.95 plus $4.95 shipping. Link is HERE