Mike, I have been working on Intimidator 4 to be my L3 bird. We are doing much the same. Mine is zipper-less also, and the two foot piece above the fin can is now a 48"piece. I have added weight to my nose cone in the from of some plywood bulkheads and a piece of 3/4" PVC with a screw on cap at the rear of the nosecone, all epoxied in. This way, I can put an Adaptec transmitter in the nose.
In the electronics bay I have a Telemetrum and a Raven. Air-frame is finished of building, but still unpainted. I have not done any ground testing and I do not know if I can get it finished in time for MHM, which was the original goal. I have three different jobs now and I am the owner on two of them, so they are eating all my time.

Even your construction method of finishing the motor mount with fins, and then sliding the assembly in to place is the same thing I have done. When we get everything taken care of and both birds have had their shakedown flights, we should have a drag race!

Mine sims in at 13,800'+ using a CTI L1115 Classic. Of course that may change as I re-weigh everything.

It seems my simulations are always short. I sure would like to get
13000'

My goal was two miles this year. Not having much luck.

at the last launch was my Intimidator 4.

I got 7500 feet actual last launch on a K-510, CTI. That's the two grainer. My first foray into 75mm. Of note Rock Sim set it at 8500 feet.

Here was my flight prep particulars.

Approximate weight 12.5 pounds (need to re-weigh, as I added a few bits). This is without motor and motor casing.

My design is not zipperless, but I had 35-40 feet of 3/8 inch Kevlar shock cord reefed in 11 bundles of 5 six-inch loops each with electrical tape wrapped twice around the center of each bundle. (Hope this is clear...)

I used a Raven with main and back up charges (surgical tubing set up) as follows:

Apogee = 2.5 grains initial charge, 3.5 grains back up charge.
Main = 2.2 grains initial charge, 3.2 grains back up.

Used a piston for main deployment. Used a 72 inch Iris Fruity Chute. Drogueless apogee deployment too.

Used two 4-40 nylon screws as shear pins in aft and main airframe.

Never saw it deploy at apogee or the main. It was lost in the clouds only to be seen at about 600 feet directly overhead with the main already deployed. It looked as if all went according to plan. It landed within 350 yards of the launch line.

I have no way of knowing if the back up or initial charges caused separation. All four went off. From the descent rate data from the Raven the post apogee free fall was around 85 feet/sec and with the main deployed it was about 17 feet per second. The descent rates demonstrate the main deployed as planned.

It had 7-9 g's of acceleration under thrust and suffered 22 g's of separation impact from apogee charge. It reached a top velocity of 460 MPH or 680 ft/sec. (Raven's are cool!)

I sim this at 13,500 with your load Mike. Thus, I expect it to hit around 11,000 feet. Maybe you'll hit two miles. I have the 5 grain Smokey Sam that I will send it up on for MHM the L-1685, which sims around the same. My sims are characteristically 10%-15% optimistic.

I am bringing two 75's for MHM. the L-1685 Smokey Sam (about 100Ns short of an M load) and the L-1395 Blue Streak.

Sounds like we're in for an L-of a time!

I am sure Mike appreciated your information, and I can say that I certainly do. Especially on the charges. You have just saved me a bunch of time. Now if I can get my contracts negotiated and signed this week, I might be able to work on a rocket and see if you guys will let me play along. 🙂

If you get yours ready in time it'll definitely be welcome!

The more the merrier!

The landing was perfect. No damage at all. Check the volumes of your airframe before looking at my charge numbers. I am flying a standard performance set up.

Of note, 1/8 inch breather holes fore and aft main frames. Both located about 6 inches behind the front of the air frame. I carefully ensured the coupler area would not bind by Kilz primer layers and sanding. Same for the nosecone.

I had a DC-40 in the NC. Turns out I didn't need it...

I love Fruity Chutes. Their new Iris line is lovely. I think I can down size to a 60 inch Iris from a 72.

It's a fun kit. Not an altitude breaker, just plain fun. Order from Wildman now, as 3Dogs got tired of dealing with that ###hole at Performance.

Mine will weigh in at about 26lbs, loaded at the pad.

18lbs = Rocket with motor casing. no chute or cords.
5.2lbs= Propellant
3.0lbs to 4.0lbs= Chute, cords, electronics, nose weight.

I will have two 72" chutes that will have a decent rate
of 15.65 ft/sec. or so.

Nose cone is 1lb 15oz (i know i know 2lbs) 😆

"StratosFear," my L3 Intimidator-4, went 13,225 feet at Oktoberfest 2011 on an AeroTech M1297. Mike, there's your solution to the 13k problem 😀

Ooh, that's a good name.

Mike,

I have a 96" toroidal chute that DaveH used on his L3. Less than 15fps if you want to use it.

Edward

MikeS, the link to the pictures seems broken or changed?

Sorry. Only so much room. I replaced with MHM 2012 pictures.

I am preparing to purchase a chute for my I-4. Weights appear to be about 16lbs empty. Any recommendations for a chute. I have been told Fruity chutes and Top Flite. It has also been suggested anywhere from 60" to 84" dia. Anybody have thoughts they want to share. I am looking for a descent rate of 20-25 fps.