Curtis Enlow
Well-Known Member
I always enjoy reading build threads and always learn a lot, so I thought I might share my IV build journey here.
This is my first rocket in some time, since my step-son & I built and flew rockets (and I won't tell you how old he is now, but 'D' engines were monsters then), but I have kept my hand in building stuff ever since, including radial aircraft engines, jet airliners, restoring a wooden sailboat, R/C planes and dabbling in electronics. So it will be fun to bring a lot of those things together in one of my favorite things ever - Rockets!
I am mostly here to glean from the tremendous knowledge base here. I have not only been warmly welcomed, but also the generous recipient of some great advice already. I can only hope that some things I do here might inspire or help someone of my own skill level, and that I might even share something new to the more experienced members.
~
First, a lot of research showed the IV's fins to be a weak part of the rocket; it seems they don't make great landing gear. So I decided, after watching John Coker's video on vacuum bagging fins, to mod the IV's fins to a simple symmetrical airfoil with tapered balsa skins and some 2oz glass and epoxy. I feel there are some aerodynamic advantages for airfoil fins on slow rockets at the price of a small amount of weight (51g vs. 31g stock, per fin) and a little added drag, plus it's fun to do
Something I did different was to leave just a little edge on the leading and trailing edges and finish the sanding to a point after bonding to the ply core (but before glassing) so they would have support and wouldn't fray or split, plus it resulted in a little more of a precise edge. I also added some 3mm Plastruct styrene triangle stock to the leading & trailing edges, as I didn't feel I would have been able to hand-sand them as precisely. I think they turned out nice.
While those were curing I tested two new, unflown MissileWorks RRC2-Minis I found (for a pittance!) in a Foodsaver canister with a 60mL horse syringe and a bit of aquarium tubing. (I plan on adding a BT tube extension and a coupler electronics bay for a HP/Dual-deploy Super IV at a later date). Without an altimeter it's not precise, but at least I know the apogee event is accurate and the main fires about where it should by releasing the seal button and feeding the syringe back in to the canister. There are methods out there (for those who know & enjoy enjoy the strange little shapes & letters on their calculators and how to use them) to actually calibrate the mL's on the syringe and capacity of the canister into altitude, but...well, this works for me. At least for now. (I think I will pick up a keychain-style altimeter soon; they seem handy)
I laid out the locations of the bulkheads, rail lugs and motor retainer on the BT for reference and upgraded the shock cord hardware (the pre-cut hole is 1/4" but the supplied hardware was 1/8"?).
Luckily, this is about when I discovered that my forearm is too big to reach the shock cord eye-bolt on the forward bulkhead in the 4" tube(!) So, not wanting to have to search for someone to reach in to attach and disconnect the shock cord I made an extension and sewed the loop with a Speedy Stitcher clone (BTW, Harbor Freight carries a stitching awl that is cosmetically & functionally the exact same tool for $6.49. I'm just sayin'... (A smaller needle can be had on the popular auction site for very little).
~
Next up, I need to epoxy in the MMT/Fwd/Mid-bulkhead assembly into the BT. I had someone rip a 45º on a 2X4 to make a fin locating jig, so I will be making that, as well as a cradle to hold the beast after the fins are on.
Again, per John Coker's suggestion I will fit but not epoxy in the aft bulkhead until I have applied internal fillets to the fins where they contact structure. (If you're new and haven't watched John's YouTube channel, you should: https://www.youtube.com/user/JohnLCoker Lots of good stuff to be found there.
Suggestions & advice are always welcomed!
C
This is my first rocket in some time, since my step-son & I built and flew rockets (and I won't tell you how old he is now, but 'D' engines were monsters then), but I have kept my hand in building stuff ever since, including radial aircraft engines, jet airliners, restoring a wooden sailboat, R/C planes and dabbling in electronics. So it will be fun to bring a lot of those things together in one of my favorite things ever - Rockets!
I am mostly here to glean from the tremendous knowledge base here. I have not only been warmly welcomed, but also the generous recipient of some great advice already. I can only hope that some things I do here might inspire or help someone of my own skill level, and that I might even share something new to the more experienced members.
~
First, a lot of research showed the IV's fins to be a weak part of the rocket; it seems they don't make great landing gear. So I decided, after watching John Coker's video on vacuum bagging fins, to mod the IV's fins to a simple symmetrical airfoil with tapered balsa skins and some 2oz glass and epoxy. I feel there are some aerodynamic advantages for airfoil fins on slow rockets at the price of a small amount of weight (51g vs. 31g stock, per fin) and a little added drag, plus it's fun to do
Something I did different was to leave just a little edge on the leading and trailing edges and finish the sanding to a point after bonding to the ply core (but before glassing) so they would have support and wouldn't fray or split, plus it resulted in a little more of a precise edge. I also added some 3mm Plastruct styrene triangle stock to the leading & trailing edges, as I didn't feel I would have been able to hand-sand them as precisely. I think they turned out nice.
While those were curing I tested two new, unflown MissileWorks RRC2-Minis I found (for a pittance!) in a Foodsaver canister with a 60mL horse syringe and a bit of aquarium tubing. (I plan on adding a BT tube extension and a coupler electronics bay for a HP/Dual-deploy Super IV at a later date). Without an altimeter it's not precise, but at least I know the apogee event is accurate and the main fires about where it should by releasing the seal button and feeding the syringe back in to the canister. There are methods out there (for those who know & enjoy enjoy the strange little shapes & letters on their calculators and how to use them) to actually calibrate the mL's on the syringe and capacity of the canister into altitude, but...well, this works for me. At least for now. (I think I will pick up a keychain-style altimeter soon; they seem handy)
I laid out the locations of the bulkheads, rail lugs and motor retainer on the BT for reference and upgraded the shock cord hardware (the pre-cut hole is 1/4" but the supplied hardware was 1/8"?).
Luckily, this is about when I discovered that my forearm is too big to reach the shock cord eye-bolt on the forward bulkhead in the 4" tube(!) So, not wanting to have to search for someone to reach in to attach and disconnect the shock cord I made an extension and sewed the loop with a Speedy Stitcher clone (BTW, Harbor Freight carries a stitching awl that is cosmetically & functionally the exact same tool for $6.49. I'm just sayin'... (A smaller needle can be had on the popular auction site for very little).
~
Next up, I need to epoxy in the MMT/Fwd/Mid-bulkhead assembly into the BT. I had someone rip a 45º on a 2X4 to make a fin locating jig, so I will be making that, as well as a cradle to hold the beast after the fins are on.
Again, per John Coker's suggestion I will fit but not epoxy in the aft bulkhead until I have applied internal fillets to the fins where they contact structure. (If you're new and haven't watched John's YouTube channel, you should: https://www.youtube.com/user/JohnLCoker Lots of good stuff to be found there.
Suggestions & advice are always welcomed!
C
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