Return to rocketry: Recerting L1 build thread

[krislhull]

After being out of the hobby for 12 years, I have decided to get back into it. I originally certed L1 in April 2003 at a Washington Aerospace Club (WAC) FAR101 launch in Orting WA, and attempted L2 at FITS that year, the last year Scott Binder hosted the launch, before WAC took it over and moved it to Mansfield. My L2 cert failed when a I made a bonehead move and overlooked epoxy on a coupler (in other words, I forgot the epoxy!!!) on the rocket. I don't think I have yet to live that one down, and i haven't seen anyone that was there in over 10 years!

Any ways, I rejoined NAR last month, and purchased a 4" Excel Dual Deploy kit from Mike at Binder Design. It arrived last week, and I am finally starting to get into the build mindset.



Today, after building a much needed work bench in my garage, I finally decided to get to work on the build. Since I am seriously considering fiberglassing the airframe, and haven't made up my mind yet, I started by beveling the fins. I made a simple jig out of some scrap wood I had and put a bevel on the leading edge of the fins. I don't think I will be doing the trailing edge as well, but I might change my mind before I attach them in place for good. This rocket won't be a high performance bird, so in my mind, it doesn't really matter that much.

 

[blackbrandt]

This will be a fun build to watch! Nice job on beveling the fins, those look really nice.

 

[fyrfytr310]

I'm in. This will be good. Definitely don't need glass on that bird but it will make it considerably stronger. Won't help much if there is a no-epoxy induced ballistic recovery though :tongue:

Any thoughts on motors yet?

 

[krislhull]

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Won't help much if there is a no-epoxy induced ballistic recovery though :tongue:

Any thoughts on motors yet?

That is true... I have a feeling that I will never live that one down! I was a 20yo idiot when I did that! I know exactly what happened, and why I forgot it!

I am still uncertain on the motor. I have a Aerotech 38/360 and 720 cases on hand, and CTI 38mm 3 and 6 grain cases on order, so it will be something for one of those. I would like to use either a H112 or I245, but will use whatever I can get my hands on. I plan to fly this thing at either the March or April WAC Mansfield launches. then hopefully go for L2 at FITS in May.

With the glass, I have several yards of 4 and 2oz cloth, so I am thinking about a layer of each, just for extra strength, even though I know it doesnt need it.

 

[K'Tesh]

Welcome Back!

If you're interested, I've simmed the Excel Dual Deploy in OpenRocket...

and the much rarer Excelerator...

 

[Forever_Metal]

it'll be fun to watch, have fun with your return to flight!!

fm

 

[Rex R]

a word on motor selection if I may...build the rocket first, then after getting a dry weight, worry about which motor to use. rockets always get heavier as you build/paint/etc. you really don't want to lock your self into a motor at the beginning of the build only to find that said motor doesn't have enough 'omph' for the finished bird. good luck,
Rex

 

[krislhull]

a word on motor selection if I may...build the rocket first, then after getting a dry weight, worry about which motor to use. rockets always get heavier as you build/paint/etc. you really don't want to lock your self into a motor at the beginning of the build only to find that said motor doesn't have enough 'omph' for the finished bird. good luck,
Rex

Of course! The motors I am thinking of are only a thought, and nothing will be decided until I finish the build, and see what is available that will work.

 

[fyrfytr310]

a word on motor selection if I may...build the rocket first, then after getting a dry weight, worry about which motor to use. rockets always get heavier as you build/paint/etc. you really don't want to lock your self into a motor at the beginning of the build only to find that said motor doesn't have enough 'omph' for the finished bird. good luck,
Rex

Agreed on not "locking in." I typically target a motor and adjust as the build progresses and the sim projection refines.

 

[Johnly]

Not that I don't think you'll find the certification process useful after being away from flying for a while, but.... If your previous HPR L1 certification was with NAR, you can have your old certification level reinstated without going through the process. It might be automatic, but just ask NAR HQ if your new membership arrives with a L0 certification status.

John

 

[mccordmw]

I certed on the Excel. It's a really sturdy airframe. It won't need any fiberglassing unless you're planning on going crazy with the largest 54mm motors it can take. I got my L1 on it with an I242 and my L2 with a J330.

 

[krislhull]

</script>dex="1">I haven't had time to really do any more work on the Excel the past couple of days, and I probably wont until the weekend due to trying to finish getting my garage straightened up and organized, but I did take the time to weigh all of the parts, and input those weights into rocksim and OpenRocket to try and get a rough estimate of performance. I am thinking that I probably wont glass this bird, even though it is tempting. Its only the 38mm version, so the largest motor it will ever see is probably a J350, if I decide to use it for my L2. but here are the results of my preliminary sims from both applications.



I have changed around the design slightly, as I do not like the idea of a 14" e-bay, since I will only be flying it with my StratologgerCF, and maybe one other altimeter once I decide on what to get. I will also be placing a Additive Aerospace mount for a Mobius Mini on the booster.

I have started gathering the parts for my next project, is going to be a 1/3.75 scale Aerobee 150. I have PML 4" tubes for the airframe, a 54mm motor mount, and just got my custom cut fins from Mike at Binder Design yesterday. I also have a custom set of decals from Mark at StickerShock, and they turned out great! I'll post a build thread on this guy after I finish building the Excel.


Kris

 

[krislhull]

After work yesterday I was able to get out and work a little on the Excel. I started by taking a sheet of G10 (bought from All Hobbies in Puyallup WA, if anyone remembers that store and Ursula!) I had stashed in a box for the past 12 years and cut out a altimeter tray. I then took a sheet of Baltic Birch I had and cut a couple of strips off it to make mounting brackets. After tacking them in place with a little CA, I made sure that everything fit nicely in the E-Bay, and epoxied them in place. I am using US Composites 150 epoxy.



While I had the epoxy mixed up, I took the time to build up the E-Bay end caps and the mid centering ring for the motor mount.



My Mobius Mini also arrived yesterday, so now I am just waiting for the shrouds from Additive Aerospace. Those should be here next week.

 

[krislhull]

Came home from work today needing some stress relief, so I worked a little on the Excel. I got the fins aligned and tacked in place with a few drops of CA, then proceeded to start the internal fillets on the first two fins.



After reading through the forums, and seeing that several people have taken epoxy and put it in squeeze bottles, I decided to do the same. It sure makes mixing up small batches pretty easy!



After getting the fins tacked on and the first fillets applied, I decided to work a little more on the E-Bay. I had picked up some copper end caps at Home Depot and drilled them out for ejection canisters, and then installed U bolts on the bulkheads. After installing a terminal block on each bulkhead, they were done.



I then soldered wires to a battery box, got it screwed into the sled, and temporarily installed the altimeter. I powered it up to make sure it works. All that is left now is to figure out switch placement and drill the vent holes.



If any one wants a good tool for making fillets in epoxy, sealant spoons work great! They're designed for spreading aircraft sealant, and we use them for making fillet seals on aircraft parts all the time.
Yard Store in Wichita sells brass ones (https://www.yardstore.com/brass-sealant-spoon.html), and I'm sure you can find the plastic ones somewhere.

 

[krislhull]

In the past week since my last update, I finished the internal fillets, finished the external fillets, filled the spirals and sanded the filler down, epoxied in the rail guide mounts, and started the final preps for priming and painting. I will probably get the rocket primed this week, and hold off on final painting until it get warmer, maybe in March or April. Heck, I might even fly it for my L1 in just primer!

Here are some photos of the progress:

Internal fillets are completed:


As are the external:


After I completed the fillets, I cut the lower body tube at 18 inches from the aft end to create a lower fin can assembly, and a drogue chute bay:


And the whole rocket assembled prior to seam filling. I took the 4" piece of airframe and cut an inch off and am using that for the E-Bay switch band, and the epoxied the remaining 3" length to the fin can using a 9" piece of PML coupler I had on hand. This also makes it easier to get to the lower shock chord mount in case I need to change it.


After filling the spirals and fairing the sections together:


And finally, attaching the rail guide nut plates and installing the aft centering ring:


I'm still waiting on my Aeropack retainer from Wildman that I ordered on the Black Saturday sale, so once that arrives, I will get it installed and finish sealing in the after centering ring. Once I track down a local source of black powder, I will perform some ejection tests as well.

 

[krislhull]

When you have a week off of work, you start getting bored, and since we had a couple days of decent weather in the mid 40's and some sun, I decided to go ahead and paint the Excel. I spent several hours on Tuesday priming and sanding the entire rocket, and after three coats of primer, I let it sit for 18 hours before putting a base coat on Wednesday morning. I went with a white lower airframe, and a forest green upper, and used Rustoleum rattle can paint from Home Depot. It turned out pretty good. It's by no means perfect, as I wasn't striving, or aiming for perfection, but it sure looks good from a few feet away! I went ahead and put the decals on it today after letting the paint cure for 24 hours, and I will clear coat it in a few days once the rain that moved in today leaves us. I added a strip of Monokote chrome trim to the E-Bay switch band, and I think it looks pretty good!









I also took the time today to finish wiring up the altimeter and sled. Once I get the top coat on everything, I will install the switch on the outside of the bay and be ready for ejection tests.

 

[K'Tesh]

Looks Great!

However, I can see it now... You launch it, and it finds the only place where the snow hasn't melted completely and evergreen trees. :wink:

 

[krislhull]

Looks Great!

However, I can see it now... You launch it, and it finds the only place where the snow hasn't melted completely and evergreen trees. :wink:

I won't be launching this until end of March at the earliest, and not very many trees near the Mansfield launch site!

 

[K'Tesh]

I won't be launching this until end of March at the earliest, and not very many trees near the Mansfield launch site!

There's a saying... If it wasn't for bad luck, I'd have no luck at all. Trust me, if I were to launch rockets in a desert, it would find the only tree/tall cactus, or bottomless pit in the area, and promptly settle there.

 

[Steve Shannon]

When you have a week off of work, you start getting bored, and since we had a couple days of decent weather in the mid 40's and some sun, I decided to go ahead and paint the Excel. I spent several hours on Tuesday priming and sanding the entire rocket, and after three coats of primer, I let it sit for 18 hours before putting a base coat on Wednesday morning. I went with a white lower airframe, and a forest green upper, and used Rustoleum rattle can paint from Home Depot. It turned out pretty good. It's by no means perfect, as I wasn't striving, or aiming for perfection, but it sure looks good from a few feet away! I went ahead and put the decals on it today after letting the paint cure for 24 hours, and I will clear coat it in a few days once the rain that moved in today leaves us. I added a strip of Monokote chrome trim to the E-Bay switch band, and I think it looks pretty good!

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I also took the time today to finish wiring up the altimeter and sled. Once I get the top coat on everything, I will install the switch on the outside of the bay and be ready for ejection tests.

View attachment 308198

That looks very nice. One thing I do that may be useful: I put the electronics on one side of the sled plate and the battery on the other so if the battery does come apart it won't destroy the electronics. Also, I use the loose battery terminals rather than the ones fixed to the battery holder.
I discovered that combination accidentally after failing to tie down a battery adequately once, having it come loose from the holder and bounce around in the av-bay. Because it was on the other side of the sled and because the lightweight terminal remained clipped to the battery with long enough wires to not pull loose, everything continued working.


Steve Shannon

 

[Binder Design]

I see you decided not to use the modular fin can assembly instructions or the provided aft thrust ring. No worries it looks nice and strong, just wanted to let anyone considering one of our kits know that this is not a stock build.

Best of luck with your certification flight and thanks for supporting Binder Design!

 

[markkoelsch]

Looking at your electronics bay, I have a couple suggestions.

1) restrain the battery. I would recommend two zip ties- one along each axis.

2) take a look at the holes in the board for the wires to pass through. I would make sure you have some strain relief where the wires pass through the sled.

 

[krislhull]

That looks very nice. One thing I do that may be useful: I put the electronics on one side of the sled plate and the battery on the other so if the battery does come apart it won't destroy the electronics. Also, I use the loose battery terminals rather than the ones fixed to the battery holder.
I discovered that combination accidentally after failing to tie down a battery adequately once, having it come loose from the holder and bounce around in the av-bay. Because it was on the other side of the sled and because the lightweight terminal remained clipped to the battery with long enough wires to not pull loose, everything continued working.


Steve Shannon

I will still probably move to battery to the aft side. I like the holders and all, but I am still weary of the battery popping out. I plan to experiment with a few possible tie down options before making a firm decision on a design change.

I see you decided not to use the modular fin can assembly instructions or the provided aft thrust ring. No worries it looks nice and strong, just wanted to let anyone considering one of our kits know that this is not a stock build.

Best of luck with your certification flight and thanks for supporting Binder Design!

Thanks Mike. You're right, I did deviate a little from the stock design instructions. I am still waiting on my Aeropack retainer to arrive, and once that gets in, I will know how much, if any, I need to sand from the inside of the thrust plate for clearance prior to installing it. I already have it primed, and ready to go on. I made the modifications so that I could change out the recovery harness if I ever have to. There is no way I could get my arm down to it if I built it stock. But your kits are VERY nice and of excellent quality! I will be back to buy at least a couple more!

 

[rharshberger]

I won't be launching this until end of March at the earliest, and not very many trees near the Mansfield launch site!

Kris, you can always come join us in Pasco, WA at the Tri-Cities Rocketeers launch site, our next scheduled launch is in March (unless we all get rocket crazy and decide to do a Feb launch), yes we do have a few trees near the launch site but the prevailing winds rarely ever push a rocket that way (unless your name is Eric R.)

 

[krislhull]

Kris, you can always come join us in Pasco, WA at the Tri-Cities Rocketeers launch site, our next scheduled launch is in March (unless we all get rocket crazy and decide to do a Feb launch), yes we do have a few trees near the launch site but the prevailing winds rarely ever push a rocket that way (unless your name is Eric R.)

Thanks for the offer, and I have considered it, but Pasco is kind of hard for a day trip! Mansfield is just over the mountains for me, and an easy day trip there and back. I do want to make it out there for a launch some time, however!

 

[rharshberger]

Thanks for the offer, and I have considered it, but Pasco is kind of hard for a day trip! Mansfield is just over the mountains for me, and an easy day trip there and back. I do want to make it out there for a launch some time, however!

Hopefully I get up to Mansfield again this year for FITS. Pasco is definitely a long day trip depending on where on the dark side you are starting from, we do have a 3 day launch in June however and we always have onsite dry camping available.

 

[krislhull]

Hopefully I get up to Mansfield again this year for FITS. Pasco is definitely a long day trip depending on where on the dark side you are starting from, we do have a 3 day launch in June however and we always have onsite dry camping available.

I plan on being at FITS in May, and hopefully go for my L2 then, assuming my L1 goes off without a hitch. The June launch does sound interesting! Ill have to look into that one! And you are right, this is the dark side! Living in the Everett area, I see it all the time!

 

[Binder Design]

I made the modifications so that I could change out the recovery harness if I ever have to. There is no way I could get my arm down to it if I built it stock.

We included a 17" long motor tube as standard with all of our new Excels going out the door to address this very concern. Unless you have arms like Popeye, it should be an easy reach. If we go any longer than that, there won't be much room left for recovery gear.

 

[MikeyDSlagle]

We included a 17" long motor tube as standard with all of our new Excels going out the door to address this very concern. Unless you have arms like Popeye, it should be an easy reach. If we go any longer than that, there won't be much room left for recovery gear.

I yam what I yam! because I can't get my arm all the way to my shock cord in my Tyrannosaur. LOL.

 

[Binder Design]

I yam what I yam! because I can't get my arm all the way to my shock cord in my Tyrannosaur. LOL.

Now that's funny. Sorry to hear that though. We really try to take all of the customer feedback to heart to produce better products but there are just some things we can't fix.