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Gary Byrum

Gary Byrum

Overstable By Design
Joined
Aug 4, 2011
Messages
6,330
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206
Location
Lincolnton NC
Sometime between 1968 and 1970, my eye caught this wickedly beautiful design in Estes DOM selection of models that Estes did not mass produce. I had already been dabbling in scratch building so I mowed enough yards to buy the parts at our local hobby store. I have absolutely no idea to this date what happened to it and many years down the road I decided I wanted to build another one, but upscale it.

Excalibur, the real one.jpg
 
1st I had to draw all of the parts in AutoCAD and scale from what was a BT 55 airframe to a BT 70. Well, this presented itself with having to make some custom parts. The nose cone and all 3 aft cones on the pods had to be turned on a lathe. Fortunately the forward pod cones and the ½ cones for the ‘port reactor bays’ could sport 50 k nose cones. This is a total of 5 BNC 50 K’s with a half one left over. So, all 4 cones get turned.

1.JPG2.JPG3.JPG
 
After that phase was done, all tubes had to be cut. The ‘port reactor bays (3) are half tubes and we all know it can be a little challenging to split tubes nice and straight especially when they’re 17” long. I knew I was going to need the fins cut to determine the length of the slots needed in the ‘bay tubes’, so I went ahead and cut all the balsa parts I needed. Unlike the “original BT 5 tubes” these BT 50 halves wanted to relax after being split so I had to cut 20/50 centering rings, aka 24mm engine blocks, in half and secure them inside the bay tubes to reinforce them. Fin slots were then cut and bay nose cones halved and hollowed somewhat, then sanded to snug around the BT 70 tube. I then secured the half cones in the bay tubes.

6.JPG
 
In this phase, all balsa parts were sanded, and shaped. Special attention was required for the crew module and the shuttle bay. Fins were glued in place and 1/4” thick dowels attached on the bottom tips of said fins because of the exposed grain endings to strengthen the fin. The lower launch lug is also mounted, sided with 2 – 1/8” dowels and a balsa part mounted on the top. This assembly is called the ‘reactor radiator’. The shuttle bay houses the upper launch lug. The crew module was then sanded against the BT 70 to for a snug fit, then slotted for the fin. In the original version a simple paper thrust cone was used at the motor mount. I opted to extend the 24mm motor mount 2” from the bottom and mount thruster ribs instead. Crew module and shuttle bay were mounted and a few fillets for the fins.


7.JPG 8.JPG 9.JPG
 
With fins being ¼” thick, I had to Dremel a dip of sorts, where the pods were going to mount. I wanted that extra bonding area for a good mount. The brace supporting the pod was made just to help me shape the curve cut in the fin as none of the pods were a dead on fit. The forward fin fairings and thruster ribs were mounted prior to mounting the pods. As you could imagine, all kinds of putty fills and fillets needed to be done and my blossoming Starship was turned upside down to dry over night.


10.JPG 12.JPG

I'll spare you all the sanding, priming and painting so we don't turn this into a novel. I was still using Krylon white primer when I built this and have since started using Rust-oleum light gray auto primer which I do like a whole lot better.
 
Nicely done so far...I remember getting the planset for that in a Mail order from penrose...Loved it...but considered it WAY beyond my pre-teen skill level...(it probably is beyond my current skill level too)
 
While I was priming and painting, my old graphics partner and I had been designing and cutting the vinyl I planned to use. The original design had round windows in the crew module but I chose square ones instead. OK, go ahead and call the upscale design police on me if you will but I wanted square windows! I also could not for the life of me locate the original logo that goes on the fin so I opted to design my own. Ain’t she a beaute?

13.JPG
 
FREEDOM LAUNCH AND WE'RE ALL WIRED UP


14.jpg


LOOK AT HER GO!


15.jpg


HERE'S THE EVENT.


16.jpg


IT'S GONNA LAND ON MY HEAD!!! :y:


17.jpg


TOUCH DOWN!


18.jpg
 
RWmarlow said:
Nicely done so far...I remember getting the planset for that in a Mail order from penrose...Loved it...but considered it WAY beyond my pre-teen skill level...(it probably is beyond my current skill level too)
Click to expand...

Making one of these from scratch is pretty time consuming. Especially when you upscale it. Semroc got around to kitting this up if you still want to build one.
 
Thanks oddman & Chuck. I knew when I started this build it would take forever, and it did. There were so many balsa parts that had to be sanded on to that BT 70 for the necessary fit. Pretty dusty job to say the least.
 
sandman said:
Very very nice!

As for the tail logo, here's what I used.

I kind of "borrowed" them from the Centuri Excalibur.:grin:

And yes, mine has round windows.
Click to expand...

Yeah, I didn't know you had those until I was finished with it. Is that the original logo for the fin? I searched high and low for many years and never saw a good pic of it. And I also never knew Centuri had an Excalibur, hmmmmm
 
sandman said:
Actually no I typed too fast.

I didn't like the Centuri Excalibur sword so I used the Centuri Stiletto sword....sorta...I just changed the sword a tiny bit. I also printed them in black for the Excalibur.
Click to expand...

I see. So yours isn't the real McCoy either. It has always befuddled me why that tail logo was never displayed somewhere. The only real references I ever found are in the very 1st photo of this thread. And I have never been able to make out what that is. The other is on the plans themselves and those are just a cartoony rendering.
 
Very nice work! I'm considering what to make for my first BT70 bird and will have to consider one of these!

What engine did you fly her on? I see you went with a 24 mm mount. Was this on a reload or...?
 
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Marc_G said:
Very nice work! I'm considering what to make for my first BT70 bird and will have to consider one of these!
Click to expand...

Marc, I prolly could have made this bird with 3/16" balsa for the fins but when I scaled everything up, that thickness was so close to 1/4" that I just went with it. I'm reasonably certain that 3/16" would suffice nicely. Give it a shot. But I'll give you an advanced warning. All of your other rockets are going to be jealous. She displays nicely. Thank you btw.
 
Here's mine at NARAM 54 this past summer.

Although it looks impressive:grin:

It wasn't:(

I used an anemic A8-3 and it only travel maybe another 5" past the it's position in the photo.

About a foot from the end of the rod.

Then it back all the way to the ground and popped it's chute.

Notice the abrupt 120 degree bend in the smoke trail...that's it switching into reverse...I meant to do that!

No damage but very embarasing:blush:

So technically...it has flown.

CIMG5364.jpg

CIMG5391.jpg
 
Last edited:
I'm glad you posted this thread. I understand and can see in the photo,you had a chute fowl on the pods. My 20 mill build has similar,---although not as big---pods and I was worried about them fowling the chute. Honestly gave little thought to multiple chutes. Looks like I need to rethink that !! I like the redundancy.
 
sandman said:
Here's mine at NARAM 54 this past summer.

Although it looks impressive:grin:

It wasn't:(

I used an anemic A8-3 and it only travel maybe another 5" past the it's position in the photo.

About a foot from the end of the rod.

Then it back all the way to the ground and popped it's chute.

No damage but very embarasing:blush:

So technically...it has flown.
Click to expand...

Looks good in the pic though. I flew mine on an E9 but I think it could handle more than that. Not a lot more, maybe a low end F. Those fins have shear written all over them.
 
hornet driver said:
I'm glad you posted this thread. I understand and can see in the photo,you had a chute fowl on the pods. My 20 mill build has similar,---although not as big---pods and I was worried about them fowling the chute. Honestly gave little thought to multiple chutes. Looks like I need to rethink that !! I like the redundancy.
Click to expand...

I was afraid that was going to happen. I figured on using a longer shock cord and relocating the chutes in the middle of it would be a solution to that so I did. Hopefully next time that won't happen.
 
It did nicely on that E9! I would have thought it might be too heavy for that motor. What's the weight of the bird (minus engine)?

And I think 1/4" finstock makes sense. I think it is more to scale that way from a visual perspective.
 
Marc_G said:
It did nicely on that E9! I would have thought it might be too heavy for that motor. What's the weight of the bird (minus engine)?

And I think 1/4" finstock makes sense. I think it is more to scale that way from a visual perspective.
Click to expand...

And I thought it would be more accurate using the scaled thickness. That's why I stuck with 1/4". The rocket weighs 11.8 oz without engine, chutes and barf. My nylon chutes don't weigh jack, so I figure another 1.5 oz with them and the barf? It did arch over some and I'm guessing the rocket plowed into the chutes at apogee. It's a pretty draggy rocket and needs an engine with a touch more power and maybe a 3 second delay.
 

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