Gemini Titan, 1/30 scale

Hi all,

Here's a photo of a scratch-built 1/30 Gemini Titan I just completed as a winter project. It's 43 inches tall, 4 inches in diameter, and weighs 4 pounds. I guess it's not a true replica because it will fly on a single (38mm) motor, not two motors like the authentic version. (I prefer single motors over clusters for reliability). The body tube is a Madcow 4" OD cardboard tube. The capsule is made of basswood and it was fashioned by a woodworking rocket colleague in Minnesota (thanks, Scott) who turned it on a lathe based on a small 3D-printed plastic replica I sent him. The four clear polycarbonate plastic fins (4mm thick) were cut for me by a plastics firm in California (TAP Plastics) according to the dimensions I sent them. They are TTW construction, epoxied to the motor mount tube and inner body tube. The black decals were provided by StickerShock23 (thanks, Mark). I'm looking forward to flying it on either an I140 or I161 for its first flight. Stability factor computes to be 1.4 caliber using Barrowman for CP, and with those motors I should have ample thrust/weight for stable flight and reach at least 1500 ft.

Very nice! Good luck on your flight

Nice looking model! Where did you get the capsule?

My woodworking friend (Scott) found and purchased a large piece of basswood on the web, then he turned it down on his lathe to the capsule shape. I had given him a small 3D-printed model of a Gemini capsule to use as a guide which I had purchased on the web. I finished it by applying diluted Elmer's wood filler, sanding with 600 grit paper, priming and painting. This link shows Scott's lathe work on it: https://rocketkraft.com/turning-nose-cone-basswood/.

Very nice build,I did a build thread a few years ago here using a Semroc BT70HD tubes and a capsule made from Balsa Machining.Mine did not look as good as yours but I did go with a cluster 24mm.Like you I made some clear fins and TTW to the engine mount.I have flown it one time and have retired it.Glad I used HD tubes and TTW as it was a hard landing.The fins took most of it and held up very well.If I fly it again I will go up one more size in my chute for a slower descent.I also went with a zipperless design and baffle.I could not find my build thread or pictures from the archives.Hope you have a great and successful flight.

Yes, I'm a little concerned about the fins upon landing. The fins themselves are extremely strong (polycarbonate) and attached firmly inside with epoxy, but I'm going to use a fairly large main chute (45") for a reasonably slow descent.

I've had good luck with my polycarbonate fins, very sturdy. On my 7.5" Titan II missile I made them fit into fin boxes held in place with plastic screws that go into the tabs from the bottom to lock them in place, never had any issue on the 10# pieces coming down at 20fps. Eventually I had an electronics failure that caused the 20# rocket to auger in, and the fins are the one thing that survived. What thickness did you use?

Frank

I have a 4 inch Gemini Titan made with one of the new Boyce Aerospace 3D printed capsules.

I used 4mm thick polycarbonate sheet (~3/16")

Thanks for the info. I'll have to look at the Boyce Aerospace site. How much does your 3D printed capsule weigh? My wood capsule is fairly heavy (~1 lb) by design so that the CG is well above the CP (1.4 calibers).

I have a 5" diameter Gemini-Titan (1/24 scale) built around the Revell plastic Gemini capsule. I have through-the-wall 3/16" polycarbonate fins with a fin-pattern similar to the LPR Estes model of 45 years ago. My GT is quite a bit heavier than yours weighing about 9.5 pounds without motors. I use a 10' diameter Top Flight chute, which gives a predicted impact equivalent to falling from a 2-foot height. I've launched it 2 or 3 times and had no fin damage.

3/16" should be plenty, I used 1/8" on my 7.5" foam Titan II missile that weighs 5# rtf on I-200 motors, and I have had no issues with that one either.

Very nice!

Aerostadt - Yes, I found your photos and construction info for your 5" on the web - very impressive!

clarinet said:

Thanks for the info. I'll have to look at the Boyce Aerospace site. How much does your 3D printed capsule weigh? My wood capsule is fairly heavy (~1 lb) by design so that the CG is well above the CP (1.4 calibers).

Click to expand...

I will have to get it out of the trailer, I am not sure exactly. I added weight to it though.

beautiful job!!

Brent said:

I have a 4 inch Gemini Titan made with one of the new Boyce Aerospace 3D printed capsules.

Click to expand...

I just got one of those recently with the exact same idea. What was the length of your body tube? (Save me a little work :wink: )

Flew my Gemini Titan for the first time on Saturday at Mini-Midwest Power (QCRS in Princeton, IL) with an I-161W to about 2000 ft. It had a nice stable flight. I used a drogue deployed by motor ejection at apogee and JL Chute Release on the main at 500 ft. Landed in a somewhat muddy part of the field (see photo) but was undamaged and virtually unscratched.

And here is a video of my Gemini Titan's second flight, on an AT I218R to about 2000 ft. [video=youtube;_vT4UyMt85c]https://www.youtube.com/watch?v=_vT4UyMt85c&feature=youtu.be[/video]