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  #21  
Old 04-22-2017, 03:19 PM
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mojo1986 mojo1986 is offline
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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
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  #22  
Old 04-22-2017, 03:26 PM
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JumpJet JumpJet is offline
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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
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  #23  
Old 04-22-2017, 03:59 PM
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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.
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  #24  
Old 04-22-2017, 04:05 PM
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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
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  #25  
Old 04-22-2017, 04:19 PM
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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.


Joe
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  #26  
Old 04-22-2017, 04:41 PM
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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
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  #27  
Old 04-22-2017, 06:51 PM
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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
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  #28  
Old 04-22-2017, 10:29 PM
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Quote:
Originally Posted by 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


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.
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  #29  
Old 04-23-2017, 02:39 PM
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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.
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  #30  
Old 04-23-2017, 02:52 PM
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Quote:
Originally Posted by ghrocketman
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.
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