Gemini Titan build

[MaxQ]

I was able to get a Sheri's Gemini Titan kit recently and I thought I'd build this when I had (or needed) down time from scratchbuilding...

I'd like to hear from other people who have built and especially from people that have flown this rocket.


The kit Sheri offers has a resin capsule, pulled (I suspect) from the Revell kit.
I had the Revell Gemini kit which I built when I was in 7th grade.
Back then I didn't realize there were a few inaccuracies in the Revell capsule.
This kit from Sheri has none of the Revell detailed parts so you won't need to deal with those inaccurate parts. You will have to do something if you crave more detail.

There are no equipment bay/fairing details such as orbital manuvering motors and other stuff, she does however provide good references for aftermarket stuff.

A few searches online got me enough close up photos of the Gemini 7/6 mission to make a few detailed parts for the fairings behind the capsule.

I added the fairing ribs to give a little more realism and help stiffen the styrene plastic fairings since I felt that part was too weak for a lot of handling and for flight.
I had dropped the capsule during assembly, and that resin capsule is one heavy part (which should help as nose weight for stability). The plastic sheet fairing got a couple of dents and creases as a result, this additional detailing allowed me an opportunity to cover it up.

Besides, they add something to the overall appearance - even though the balsa strips I used are a little oversized.

 

[MaxQ]

Depending on how much realism you want, the capsule will benefit with some extra work and attention.
I had to rescribe some detailing in the way of panel lines and texture as it apears the RTV molds have seen a lot of use, and some fidelity of detail was not present.

The obvious dimensional mismatch between the conical forward section of the capsule to the capsule body could use a trim ring to cover that up.

 

[MaxQ]

The really fine part of this kit is the engine bell assembly which is also designed to serve as the motor retention.

This is really nice as you can fly this thing with the beautifully machined aluminum nozzles in place.

If you carefully drill and trial fit the clear plastic fin hardware mounting brackets you should have little trouble workng around them and the kit provides lots of engine plumbing detail which I'm anticipating doing next.

 

[MaxQ]

The biggest challenge that I had with this build was dealing with the airframe body tube provided in the kit.
This is a hefty tube, thick walled. Industrial strength. It is not a smooth glassine finished tube.

You will need to do the usual "drill" when finishing a body tube - filling the spiral seams.

What vexed me was the degree of fiber and fuzzies that repeated sanding appeared to lift after every treatment.

Repeated applications of primer were needed to get this problem under control.

I used two full cans of Krylon primer (the new stuff) - four coats and four sandings to get the level of finish I felt satisfactory (and this isn't a competition bird.......just a fun fly/sport scale model).

 

[MaxQ]

The overall size of this rocket is still pretty impressive for those who may be more accustomed to mid sized high power rockets ...I had some trouble getting it in frame for the picture.

Looking forward to the painting and finishing...

 

[ben_ullman]

looking good Jim! Can't wait to see it fly!

Ben

 

[MaxQ]

Thanks Ben.
Due to the engine bells, I'm limited to two 29mm's.

I'll be pondering the best way to get two lit - together, as this isn't a "deuce"
with vectored MMTs..

I guess two Cessaronis would work.

 

[BsSmith]

Looks great!

I built one last year completely stock, with no aftermarket details. Here is a photo gallery of it's first launch. https://cia-rocketry.smugmug.com/Lo...at-Dodds-Park-1/6682220_uofsN#426564306_jtDB6

Unless you have flush aft closures, the Titan can only be launched on G77-4s because they are the only motors with a 4 second delay that will fit in the nozzles. I tried putting the new G80-7s in it, but it zippered. Will the Pro-29s fit?

To light it, if you have a club with multiple launch systems hook up each igniter to a different pads clips. I use magnalite for mine, and it hasn't had a problem.

 

[MaxQ]

Looks great!

I built one last year completely stock, with no aftermarket details. Here is a photo gallery of it's first launch. https://cia-rocketry.smugmug.com/Lo...at-Dodds-Park-1/6682220_uofsN#426564306_jtDB6

Unless you have flush aft closures, the Titan can only be launched on G77-4s because they are the only motors with a 4 second delay that will fit in the nozzles. I tried putting the new G80-7s in it, but it zippered. Will the Pro-29s fit?

To light it, if you have a club with multiple launch systems hook up each igniter to a different pads clips. I use magnalite for mine, and it hasn't had a problem.

Well, that certainly gives me something to think about.
I want to make sure I have motor options...like flying with two H's to avoid early ground contact.

Flush aft closures?
I can understand the retention during ejection charge, but there also needs to be a thrust ring for the forward motion on ignition doesn't there? The G77 - 10 in the picture has one...did this motor fit? Doesn't look exactly flush on the aft end to me...
Maybe I'm not getting what you're explaining...
(Thanks for the launch pictures, it looks great)

 

[BsSmith]

The G77 comes with a paper ring that you can glue onto the end, I don't glue it on. Instead, I have thrust rings glued inside the motor tubes. They're just pieces of spent single use motors glued inside the tubes.

 

[MaxQ]

Just pulled the two aluminum engine bells off of the plywood motor flange and checked the fit of an Aerotech 29mm reload (29/240).

The cavity in each engine bell is machined to take a 29mm case, but not the aft closure/thrust ring that comes with the reload hardware.
It is darn close...but it just won't go in.

This is a big problem if you want to use standard reloads...I'm not even sure an aerotech G reload would fit.

Guess the single use G's would work...as Brian has the picture to prove it.
Wow...I need to rework this one.

I'm concerned about ultimate flight weight as this thing is going to be heavy, with the airframe tube, paint, resin capsule etc.
I'd like to have flexibilty of motor choices.

 

[MaxQ]

The G77 comes with a paper ring that you can glue onto the end, I don't glue it on. Instead, I have thrust rings glued inside the motor tubes. They're just pieces of spent single use motors glued inside the tubes.

Thanks...you answered my question and I understand how you accomodated it.
I guess putting the thrust ring on the inside of the motor tube kinda limits your motor choices now...given motor length varies ....

 

[Stymye]

I have always put thrust rings inside my rockets to accomidate the longest motor I plan to use .. than I simply drop in spacers for the shorter ones.I've done this for years. I keep a number of reuseable spacers in my range box, it doesn't take that many to cover all the bases

It's fast to load, keeps the aft of the rocket clean looking and makes the spent motors simple to remove as well.I much preferr it to masking tape or glueing on rings.
I'm already at the pad loading up by that point
( ofcourse I can still install motors with built in thrust rings as well)

it's one way to go and in most of my midpower birds I could install every motor in that photo with very little effort and in very little time.

(I keep diameter adapters for the smaller motors in my box also)

 

[blackjack2564]

Take the largest motor you intend to use. Mount your thrust ring for that. Use spacers of various lengths for shorter motors to fit.

AND CTI DOES have a new flush mount closure for 29mm . AND with their new grain spacers, you could fit your tube for the largest case you want to fly and then use the internal grain spacers for different size loads. I.E fit for a 4grain case and use spacers in the same case to fly 2, 3. grain reloads!

Here is the thread discussing these new spacers in case you have not heard of them. Yes they work, I've seen them.

https://www.rocketryforum.com/showthread.php?t=5729

 

[MaxQ]

Take the largest motor you intend to use. Mount your thrust ring for that. Use spacers of various lengths for shorter motors to fit.

AND CTI DOES have a new flush mount closure for 29mm . AND with their new grain spacers, you could fit your tube for the largest case you want to fly and then use the internal grain spacers for different size loads. I.E fit for a 4grain case and use spacers in the same case to fly 2, 3. grain reloads!

Here is the thread discussing these new spacers in case you have not heard of them. Yes they work, I've seen them.

https://www.rocketryforum.com/showthread.php?t=5729

Well...I could deal with motor spacers all the way up the inside of the motor tube if I have to...they probably get a little crusty after awhile , but I can deal with that. It does all depend on a flush aft closure motor to pull it off (that means all new hardware in the 29mm line, ......unless Aerotech has a flush aft closure.


I sure hope they (Cessaroni) do have a flush mount...this is the part (see the picture) that won't fit inside the engine bell cavity....the cavity will take the 29mm case width, nothing more.

https://www.pro38.com/products/pro29/pro29.php#

 

[BsSmith]

I'm concerned about ultimate flight weight as this thing is going to be heavy, with the airframe tube, paint, resin capsule etc.
I'd like to have flexibilty of motor choices.

Mine is 6.6 pounds at take-off, and it flies perfectly on the G77s. It even deploys the chutes exactly at apogee.

The fins might have problems holding up to an H flight also, the root for them is very small.

 

[MaxQ]

Mine is 6.6 pounds at take-off, and it flies perfectly on the G77s. It even deploys the chutes exactly at apogee.

The fins might have problems holding up to an H flight also, the root for them is very small.

I heard from another builder that pranged his on two G's.

Any idea what altitude you got on the G77's?

 

[blackjack2564]

Here's a shot of both the closure and the spacers. AT hardware can also use a flush closure. I think Wildman has them. Little heard about but they are out there I have seen them.

 

[BsSmith]

Any idea what altitude you got on the G77's?

About 600'.

There's a video on the NSL website that shows it on 2 G80s, it got to about the same altitude.

 

[bsexton]

Other than the engine bells this kit looks painfully simple for the money. I have to say the "extra" work you've done on the capsule will make a nice difference.

 

[BRC]

Not a Hot Rocket but a Neubauer with a G80-7 from this past weekend..

 

[BsSmith]

Another thing you might want to do is ditch the 1/4" lugs and put rail buttons on it. I always launch mine off an 8' rail.

 

[MaxQ]

Another thing you might want to do is ditch the 1/4" lugs and put rail buttons on it. I always launch mine off an 8' rail.

I agree...I'll be looking for some rail buttons.

 

[dwmzmm]

Here's a few pics of Lannie Phillips (of the NHRC # 365 Section) Sheri's Hot Rockets Gemini Titan model; took these pics at a recent modroc contest down at JSC earlier this year.....I don't think he's flown his yet (wants to get some experience on HPR clustering first)....

 

[bsexton]

Are all of the body details wraps or is it a combination of painting and wraps? This model looks very nice.

 

[MaxQ]

<took these pics at a recent modroc contest down at JSC earlier this year>

Nice line up ..

What Apollo Little Joe II kit is that?

 

[BsSmith]

Are all of the body details wraps or is it a combination of painting and wraps? This model looks very nice.

It's a combination of both.

The white and silver are painted on, and the black is wraps.

 

[MaxQ]

It's a combination of both.

The white and silver are painted on, and the black is wraps.

I'll bet that chrome isn't paint.....

 

[MaxQ]

Here's a shot of both the closure and the spacers. AT hardware can also use a flush closure. I think Wildman has them. Little heard about but they are out there I have seen them.

I have a call into him and some other vendors...we'll see what shakes out.
if nothing...I may have to see about remachining these cavities at the back of the engine bells to get a standard Aerotech 29mm to fit.

 

[dwmzmm]

<took these pics at a recent modroc contest down at JSC earlier this year>

Nice line up ..

What Apollo Little Joe II kit is that?

That's the Sheri's Hot Rockets Apollo Little Joe, only that Lannie made it a later round....looks great, doesn't it?