Looking for Information On Estes #1279 Nike-Ajax

[mojo1986]

I am about to attempt a restoration of an Estes Nike-Ajax, kit #1279. It is missing its nose cone (BNC-20CB) and eRockets/Semroc doesn't stock it. As a starting point, does anyone have one of these that they could measure for me? I need the exposed length, i.e. from the shoulder forward. Even better, does anybody know of a vendor who sells these?

Joe

[Polaris1324]

Is this it?

http://www.erockets.biz/semroc-balsa-nose-cone-bt-20-1-75-ogive/

[mojo1986]

Is this it?

http://www.erockets.biz/semroc-balsa-nose-cone-bt-20-1-75-ogive/


Yes! Thanks! That's bittersweet :mad: more bitter than sweet............I just made an order to eRockets! Darn! I don't know why I missed that cone??

OK, anyway, thanks again for your help. I'll pick one up on my next order.

Joe

[mojo1986]

Hmmm.............although the link supplied in this thread by Polaris1324 worked for me, when I Google eRockets and go to their site, then choose Semroc Parts, Balsa nose cones, BNC20..............the cone I'm looking for doesn't show in their product list! Which explains why I didn't find it before.

Strange!

[astronwolf]

Unless Randy updated that Semroc nose cone, it doesn't have the right shape. I compared one to an original.

[mojo1986]

Unless Randy updated that Semroc nose cone, it doesn't have the right shape. I compared one to an original.


Can you post the dimensions of the original here?


Joe

[JumpJet]

Attached is an image of what the original BNC-20CB cone should look like.



John Boren

[mojo1986]

Thank you, John!

[astronwolf]

Mojo, I thought this thread was familiar.

You asked the same questions 2-3 years ago:
http://forums.rocketshoppe.com/showthread.php?t=13628&page=2&pp=10&highlight=BNC-20CB

In that thread I posted a picture of a semroc BNC-20CB and an original Estes BNC-20CB.

I guess you forgot....

[mojo1986]

Mojo, I thought this thread was familiar.

You asked the same questions 2-3 years ago:
http://forums.rocketshoppe.com/showthread.php?t=13628&page=2&pp=10&highlight=BNC-20CB

In that thread I posted a picture of a semroc BNC-20CB and an original Estes BNC-20CB.

I guess you forgot....


Wolf, thanks for the refresh. Yeah, totally gone out of my mind. I'm claiming Senior's Privilege on this one.

[astronwolf]

That's OK. It's not possible to talk too much about the BNC-20CB. ;-) Or topics like the evolution of the BNC-20L or what the other side of the Estes Bandit looked like. Carry on....

[mojo1986]

Hey guys, I need a bit more info on this kit. Can anyone tell me either:

The total length of the BT-50 body tube (part E in the exploded view), or, if your kit is already built,

The EXPOSED length of the same tube after its insertion into the BT-55 booster tube (so, from the 5055 adapter ring forward to the front edge of the BT-50 tube).


http://www.spacemodeling.org/jimz/estes/est1279.pdf



Thanks in advance!


Joe

[mwtoelle]

The length of the BT-50 in the Nike-Ajax kit is 18". An unsuffixed BT designation in Estes instructions means the full uncut length available from Estes. That means 18" with the exception of the BT-30 (9"), the BT-70 (17.5"), the BT-80 (7.6"), and the BT-101 (16.5"). Further, the uncut length of the BT-40 was 13.75".

[mojo1986]

Hi, Mike. Thanks for your input. Yes, I thought the same thing, but there's a problem: 3.9 inches of the BT-50 is buried inside the BT-55 booster section. That leaves 14.1 inches of exposed BT-50. Trouble is, when I measured the section of exposed BT-50 that I removed, it was 12.5 inches. So did the original builder get it wrong, or was the BT-50 less than 18 inches. Furthermore, when I put the 12.5" replacement tube in place, it just looks too darn long.

So while your analysis makes sense to me, I still need an explanation for the inconsistency. That's why I'm hoping that someone here can actually measure the length of the tube in a kit, or measure the exposed length of the BT-50 in a built one.


Joe

[SEL]

Hi, Mike. Thanks for your input. Yes, I thought the same thing, but there's a problem: 3.9 inches of the BT-50 is buried inside the BT-55 booster section. That leaves 14.1 inches of exposed BT-50. Trouble is, when I measured the section of exposed BT-50 that I removed, it was 12.5 inches. So did the original builder get it wrong, or was the BT-50 less than 18 inches. Furthermore, when I put the 12.5" replacement tube in place, it just looks too darn long.

So while your analysis makes sense to me, I still need an explanation for the inconsistency. That's why I'm hoping that someone here can actually measure the length of the tube in a kit, or measure the exposed length of the BT-50 in a built one.


Joe

Hi Joe,

I have an open kit around here somewhere. I'll dig it out and measure the tube for you.

Sean

[mojo1986]

Sean, I really appreciate it!


Joe

[SEL]

Sean, I really appreciate it!


Joe

No problem, Joe. The BT50 in my Ajax kit is 18'' long HOWEVER there is a post-it on the outside of the kit bag the reads 'Crimped BT50'. The BT50 in the bag is not crimped, so I may have replaced it back when I was getting ready ( or so I thought) to build it. I didn't make a note to cut the tube, so I still have to assume that the original was 18'', but have to mention it here in the spirit of full disclosure.

S.

[mojo1986]

Sean, many thanks! Well, that ALMOST clears things up. Now if only that darn tube was the original, we could be 100% certain. :(

[JumpJet]

According to my records the Nike Ajax uses the following tube sizes.

BT-55KA P/N 30387 10.625" Long
BT-50 P/N 30352 18.0" Long


John Boren

[mojo1986]

Thanks, John. That settles it, BT-50, 18" long. Thanks to all who responded. I appreciate the support.


Joe

[mojo1986]

A final comment on this kit.............at 30" in length and BT-55 based, what was Estes thinking when they powered this rocket with 18 mm??? I'm seriously considering working the 18 mm engine mount out and fitting this thing up for 24 mm power.


Joe

[JumpJet]

I'm sorry Joe but the Nike Ajax only weighs in at 2.6 ounces so a C motor has plenty of power to fly it. Other long models powered by C motors are LTV Scout, Andromeda and Solar Sailor just to name a few. So what I'm sure the designers at Estes were thinking back in the day was a C would work just fine on this model.

For those who like to upgrade to larger motors go for it but a C motor will fly it just fine.




John Boren

[tbzep]

The Cobra 1500 was BT-55 and about 5 ft tall. I've flown mine on a small field with a B6-2. A C6-5 should kick the Nike-Ajax plenty high. With an actual delay close to 2 seconds, I bet it will safely fly on an A8-3 on a calm day and I'm sure a B6-4 would be an ok motor for a confined school yard.

Now if you are looking for a scale sledgehammer launch like a real Nike booster, a 24mm mount and a C11-5 would kick it pretty hard, and a D12-5 or 7 would be way up there, but with all that forward fin area, you'd probably need to add more weight up front.

[mojo1986]

Yes, when it comes to scale sounding rockets and ground-to-air interceptors, I like a scale launch. I don't dispute the fact that it can be flown safely and well on 18 mm, I just feel that D power would have been a good choice for this rocket to add realism to the launches. Different strokes for different folks.


Joe

[mojo1986]

By the way, John, regarding your comment about the LTV Scout, I believe 18 mm is the right choice there. A 'D' engine would give a too rapid ascent.

If I proceed with the 'D' modification on the Nike Ajax, I'll find the CG with a 'C' engine installed, then replace the motor mount with a 24 mm and add lead shot to a hollowed out nose cone to bring the CG back forward to the original point. With such a long rocket, adding the shot so far forward means you can get away with a very small weight increase.

Maximum performance. Scale liftoffs. I launch in a double school yard. As long as I select the correct 'chute size and point the launch pad to allow for wind direction, I can really get away with some towering flights without losing the rocket. That's not to say it hasn't happened. :o


Joe

[JumpJet]

Joe,

I have NO issue with anyone upgrading the motor mount on just about any rocket they wish to.


Even though I have NO Skin in the Game on this model since I didn't design it I just felt your comment

"what was Estes thinking when they powered this rocket with 18 mm???"

Would lead people to believe it would be under powered when in fact it would have plenty of power using a C engine.

If you like scale type launches where the rocket rips off the pad that's great, use what ever motor you feel will give you the performance you are looking for.

John Boren

[mojo1986]

OK, John, I understand your issue with the way I stated it. Never wanted to give the impression that the model was underpowered. I know that Estes puts a lot of work into getting things right and ensuring that their products are safe. Just felt that as the scale rocket that it was, it screamed for 'D' power. Hope I didn't ruffle feathers.


Joe

[sandman]

I'm sorry Joe but the Nike Ajax only weighs in at 2.6 ounces so a C motor has plenty of power to fly it. Other long models powered by C motors are LTV Scout, Andromeda and Solar Sailor just to name a few. So what I'm sure the designers at Estes were thinking back in the day was a C would work just fine on this model.

For those who like to upgrade to larger motors go for it but a C motor will fly it just fine.




John Boren

My Nike Ajax kit used 18mm motors and was the exact same scale as the Estes kit and a "C" motor flies it just fine with a respectable altitude.

The problem with 24mm in the Ajax is the stage transition is only a BT-20. The sometimes "shotgun" ejection of the 24mm motors would probably...let's say "overwhelm " the restriction and more than likely blow it apart.

If you separate it at the transition, that would work but all the recovery stuff in the booster would mean more nose weight so, you gain very little.

[ghrocketman]

The transition on an Estes Nike-Ajax is BT-50 to BT-20. All the recovery 'laundry' is in the BT-50.
I built 3 original Estes kits.
The first was the ONLY one that got 18mm power.
The other two got 24mm.
The 'extra kick' from a C11-5 or D12-5/7 makes for a more 'scale' liftoff.
Actual 'Nike' missiles really BLAST-off.
I have flown them on as small as a B6-2 and as large as an E15-7.
40 n-sec of a full-load E is a bit much. On the field I used to fly, the D12-5 was almost a perfect motor with a 12" chute. My 18mm one flew really well on 18mm Aerotech D13's and D10's.

[tbzep]

The transition on an Estes Nike-Ajax is BT-50 to BT-20. All the recovery 'laundry' is in the BT-50.
Not according to the instructions.

[ghrocketman]

The instructions are WRONG then. The upper-most short tube above the TA-2050 is a 2" section of BT-20.
The wadding/chute/shock cord are all in the BT-50 below the balsa adapter.
NO WAY could you pack an Estes 18" chute, shock cord, and wadding into a 2" piece of BT-20.

[tbzep]

The instructions are WRONG then. The upper-most short tube above the TA-2050 is a 2" section of BT-20.
The wadding/chute/shock cord are all in the BT-50 below the balsa adapter.
NO WAY could you pack an Estes 18" chute, shock cord, and wadding into a 2" piece of BT-20.
I think the issue is that folks (including me) are forgetting that there are actually three sizes of tubes in the kit, not two. BT-55 for the Nike booster, BT-50 for the upper stage, and BT-20 for the very short payload section, effectively making that portion a long nosecone. We are all mentally seeing it break apart in the correct location, at the "nosecone", but the "nosecone" consists of a 20/50 transition, a 1.5" BT-20 and a BNC-20CB nosecone.

[ghrocketman]

Tbzep- that's a GREAT way of looking at it.
The TA-2050A transition, short BT-20 tube, and balsa cone (with the forward-most 8 little fins and vanes) all comprise the Nose (warhead) section.
I'm not sure that transition and cone were ever used on any other Estes kits.

[mojo1986]

Can anyone tell me what the thickness is of the forward small steering fins on the Nike Ajax? The booster and main stage fins are 3/32". Are the small fins the same thickness? I notice in the instructions that they are taken from two different die cut balsa sheets (79A and 79B). So I suspect that the small fins are thinner.

Joe

[SEL]

Can anyone tell me what the thickness is of the forward small steering fins on the Nike Ajax? The booster and main stage fins are 3/32". Are the small fins the same thickness? I notice in the instructions that they are taken from two different die cut balsa sheets (79A and 79B). So I suspect that the small fins are thinner.

Joe

I can check when I get home this afternoon ~4 pm Pacific.

[ghrocketman]

The large and small fins on the sustainer "Ajax" portion of an Estes Nike Ajax are 1/16" balsa and thinner than the fins on the "Nike" booster.
Another interesting fact is that the booster "Nike" portion of a Nike Ajax only has THREE fins where the sustainer "Ajax" portion uses FOUR fins.

Due to all these forward fins on the sustainer that don't align really at all with the booster, the drag is pretty high for a BT-55 rocket. Another good reason to upgrade to 24mm motor mount.

At one point Estes listed an A8-3 as a 'suggested' motor for this kit. Flying one on an A8-3 would be a disaster in anything but calm conditions. A buddy flew his on one in my backyard in around 1982 or 1983. It MAY have got to 100' apogee and ejected at about 30' off the ground. The chute was not fully open before 'touchdown'. He got lucky there was no damage, but he never used less than a B6-4 after that. I know I never used less than a B6-4.

[tbzep]

Today's A8-3 is about a 2.2 second delay. It would probably be about right on a calm day as long as a person doesn't build heavy. Low and slow for sure, though.

[mojo1986]

Thanks, GH.

By the way, 24 mm mount has been installed. I set it up to take an Estes E9, and so I can also use a D12 with a 1" spacer. I think it's going to fly really impressively. It took four Estes lead weights behind the nose cone to bring the CG back forward where Estes intended it to be.

Joe

[mojo1986]

Thanks, Sean. Unless you have something further to add, GH's info was what I needed.

Joe

[ghrocketman]

I would probably fly it first on a C11-5.
I know mine flies with no added noseweight with a D12-5, but needed weight with the E9.

[njrick]

this was always one of my favorite Estes kits....I loved flying this rocket as a kid. I grew up outside of Philadelphia and there was an old Nike Ajax base in Newtown Pa. that was about 5 miles from my home...was converted into a park but the bunkers etc are still there.

[mojo1986]

this was always one of my favorite Estes kits....I loved flying this rocket as a kid. I grew up outside of Philadelphia and there was an old Nike Ajax base in Newtown Pa. that was about 5 miles from my home...was converted into a park but the bunkers etc are still there.



Any old photos of the site or missiles kicking around?

[njrick]

I don't have any old pictures...but I am attaching a link that discusses the old site

http://www.historicbuckscounty.org/richboro/nike/

[mojo1986]

I don't have any old pictures...but I am attaching a link that discusses the old site

http://www.historicbuckscounty.org/richboro/nike/


Thanks, that was very informative.

Joe

[njrick]

the link shows a Nike base at Marlton NJ which is right down the road from my office...its hard to imagine what having operation Nike bases would be like now ....different times..but they literally ringed Philadelphia with these.

the Nike Ajax is one of those iconic Estes kits that I would love to see come back. I think I built at least 3 of these when I was younger. So many great memories from Estes...just a very special part of my childhood.