Joshua F Thomas
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A One Day* build of an Estes Der Max Red kit upgraded to a 24mm engine mount.
* doesn't include painting and decals
** assumes you have way too much free time to spend on rocket building
--
So my local vendor FlightSketch has been hosting a "Goblin vs. Der Red Max" competition, giving me the excuse to buy one of both. I went crazy on the Goblin with a 4" Loc kit, but generic for the Der Red Max with a regular Estes kit. After looking it over, I realized I could probably do the whole thing in one sitting. Then I decided I should make it interesting. So here's how to take your Estes Der Red Max, up-build it for 24mm motors, and give it a little additional extras.
Titebond II will be the glue of choice for the whole project.
You're going to want to start with the engine mount. The kit provides for a basic 18mm mount with cardstock rings. For 24mm you'll need a 24mm engine tube (10 cm long), two 24mm centering rings to BT-60, a 24mm engine block, a 24mm engine retainer, and for our improved shock cord mounting a 24mm to 29mm centering ring. Tie kevlar line around engine tube well, cut slots cut in the forward centering ring and extra centering ring and feed through. The 24-to-29mm centering ring is triple duty: It holds the engine retainer clip down; it anchors the shock cord; and it provides a small bit of extra stability for the forward centering ring.
With the 10 cm x 24mm tube, you can fit either 24 x 70mm motors (Estes D) or 24 x 95mm motors (Estes E), as well as 18mm motors with an 18-to-24 adapter. The 'D' motors will need an engine spacer. Quest and Aerotech 24mm composites should also fit.
Don't be like me and use too little kevlar cord and then have to add even more, before you add on your elastic cord.
On to the body tube. If you're going for looks, as I am - fill the body spirals your way. I used thin CWF applied with a dull blade. Let dry, then sand.
Prepare your fins whatever way you choose - paper, naked, CWF - it's all good. I did CWF followed by 120 grit, 220 grit, and 500 grit at the end. A little of the balsa shows, but it's Good Enough (tm). This would have gone faster but I put the fins under some books after the CWF dried, to make sure they didn't warp from the extra moisture. The again for 30 minutes after sanding. If you want this bird to vanish into the sky, round or airfoil the fins. I left them flat.
Meanwhile, the nosecone. As we'll see from later OpenRocket sims, using a D or E motor in the Der Red Max pushes the stability below 1 caliber. In order to get this back up, we're going to modify the nosecone and add 10g of mass to it. By default the nosecone is 22g.
The hole in the top of the nosecone is far to small to get anything inside. It's dremel time! We'll cut about 1/4 of the radius on the inner transition. Since we're here, let's add two slots and use them as shock-cord mounts, because the built in nose cone attachment mount is tiny.
Now we have room to put extra mass inside. We need something that won't go anywhere and can be dialed in for exact mass. FixIt epoxy putty is the tool of choice here.
Measure up two equal parts to make 10g, combine very very well, and then hammer it into place inside the nosecone with a dowel. Sets up in an hour, turns rock hard in 24.
(continued)
* doesn't include painting and decals
** assumes you have way too much free time to spend on rocket building
--
So my local vendor FlightSketch has been hosting a "Goblin vs. Der Red Max" competition, giving me the excuse to buy one of both. I went crazy on the Goblin with a 4" Loc kit, but generic for the Der Red Max with a regular Estes kit. After looking it over, I realized I could probably do the whole thing in one sitting. Then I decided I should make it interesting. So here's how to take your Estes Der Red Max, up-build it for 24mm motors, and give it a little additional extras.
Titebond II will be the glue of choice for the whole project.
You're going to want to start with the engine mount. The kit provides for a basic 18mm mount with cardstock rings. For 24mm you'll need a 24mm engine tube (10 cm long), two 24mm centering rings to BT-60, a 24mm engine block, a 24mm engine retainer, and for our improved shock cord mounting a 24mm to 29mm centering ring. Tie kevlar line around engine tube well, cut slots cut in the forward centering ring and extra centering ring and feed through. The 24-to-29mm centering ring is triple duty: It holds the engine retainer clip down; it anchors the shock cord; and it provides a small bit of extra stability for the forward centering ring.
With the 10 cm x 24mm tube, you can fit either 24 x 70mm motors (Estes D) or 24 x 95mm motors (Estes E), as well as 18mm motors with an 18-to-24 adapter. The 'D' motors will need an engine spacer. Quest and Aerotech 24mm composites should also fit.
Don't be like me and use too little kevlar cord and then have to add even more, before you add on your elastic cord.
On to the body tube. If you're going for looks, as I am - fill the body spirals your way. I used thin CWF applied with a dull blade. Let dry, then sand.
Prepare your fins whatever way you choose - paper, naked, CWF - it's all good. I did CWF followed by 120 grit, 220 grit, and 500 grit at the end. A little of the balsa shows, but it's Good Enough (tm). This would have gone faster but I put the fins under some books after the CWF dried, to make sure they didn't warp from the extra moisture. The again for 30 minutes after sanding. If you want this bird to vanish into the sky, round or airfoil the fins. I left them flat.
Meanwhile, the nosecone. As we'll see from later OpenRocket sims, using a D or E motor in the Der Red Max pushes the stability below 1 caliber. In order to get this back up, we're going to modify the nosecone and add 10g of mass to it. By default the nosecone is 22g.
The hole in the top of the nosecone is far to small to get anything inside. It's dremel time! We'll cut about 1/4 of the radius on the inner transition. Since we're here, let's add two slots and use them as shock-cord mounts, because the built in nose cone attachment mount is tiny.
Now we have room to put extra mass inside. We need something that won't go anywhere and can be dialed in for exact mass. FixIt epoxy putty is the tool of choice here.
Measure up two equal parts to make 10g, combine very very well, and then hammer it into place inside the nosecone with a dowel. Sets up in an hour, turns rock hard in 24.
(continued)