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  #1  
Old 07-10-2010, 03:49 PM
rocketpunch rocketpunch is offline
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Default Honest John Maxi Brute question

Years ago a I bought an Estes Honest John Maxi Brute on clearance at a hobby shop. Well, I have finally decided to build it.

My question regards the motor mount. I am concerned that flying it on a D motor might be a little under powered. So I was thinking of flying it on a larger 24mm motor, say an E or F. Having personally never flown anything over a D motor, do I need to do anything different to the motor mount to accommodate the larger motor? Thanks!
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Old 07-10-2010, 04:08 PM
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LeeR LeeR is offline
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I switched to a 29mm mount, since I planned to fly it on Aerotech F12J single use Black Jack motors, which were awesome. But, no longer made (this was back in the 90s). Doing it over again, I'g leave it 24mm, but use a heavy wall motor tube, and beef up the centering rings. I've done this on other Estes D rockets. You do not need to replace paper centering rings, just add some balsa or basswood "spokes" running outward from the motor tube, to stiffen up the centering rings. You could substitute thin plywood, but not really necessary. Many of the E and F reloads for the Aerotech 24/40 casing would be great, as well as E15 and E30 single use Aerotech 24mm motors.
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  #3  
Old 07-10-2010, 04:22 PM
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tbzep tbzep is offline
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Quote:
Originally Posted by rocketpunch
Years ago a I bought an Estes Honest John Maxi Brute on clearance at a hobby shop. Well, I have finally decided to build it.

My question regards the motor mount. I am concerned that flying it on a D motor might be a little under powered. So I was thinking of flying it on a larger 24mm motor, say an E or F. Having personally never flown anything over a D motor, do I need to do anything different to the motor mount to accommodate the larger motor? Thanks!


It flies just fine on D12-3's. There's nothing wrong with flying low enough to see the whole flight.

However, if you want to fly higher and/or see more flame, just stick a 24mm E in the regular mount. The stock mount should handle Aerotech E15 singles and E18 reloadables with no problem. If you are into E30's, you might beef it up a little just for peace of mind. I don't see much point in putting an F in it, considering you will spend half of the time trying to find it in the sky at those altitudes.

I wouldn't fly it on an Estes E9. It has lower peak thrust and would need a straight vertical launch and zero wind to have a safe flight.
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Old 07-10-2010, 05:03 PM
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Royatl Royatl is offline
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Quote:
Originally Posted by rocketpunch
Years ago a I bought an Estes Honest John Maxi Brute on clearance at a hobby shop. Well, I have finally decided to build it.

My question regards the motor mount. I am concerned that flying it on a D motor might be a little under powered. So I was thinking of flying it on a larger 24mm motor, say an E or F. Having personally never flown anything over a D motor, do I need to do anything different to the motor mount to accommodate the larger motor? Thanks!



Normal motor mount will handle an E15 or E-reloadable fine. Should be fine for E30 as well, but you could put little triangular gussets between the tube and the centering ring for a little extra strength.

I *would* recommend a thicker walled mounting/stuffer tube, but not for strength reasons, but because ejections and "delay hibachi" effects from reloads will burn away the tube in front of the motor after a few flights! Either that, or always put a bond paper liner into the stuffer tube, and replace it after each flight, even with D motors.
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  #5  
Old 07-11-2010, 12:55 AM
rocketpunch rocketpunch is offline
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Thanks for the info guys. I'll probably try and get a better motor tube and re-enforce the centering rings with some balsa gussets. Can't hurt right? I'll probably give Aerotech one time E-15s a shot.
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  #6  
Old 07-11-2010, 01:53 AM
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I should mention that MY old Maxi-Brute HJ, the one I originally built in 1979, was modified with a conversion kit I got from FSI to be able to use their F100 and E60 motors. It was nothing more than a motor mount tube (for FSI motors... unlabeled aerotech motors barely fit) and two centering rings that were basically 1/8" particle board! I flew it a few times on F100 motors with no problem, but the fins kept getting damaged with every landing. In 1990 I cut open the boat tail and epoxied four 3/8" pieces of balsa to the motor tube that served as pylons for my carved balsa fins, covered with silkspan and epoxy (replacing the vacuformed plastic ones). I flew it a number of times with F100 and some 24mm Aerotech motors.

I've got a couple spare HJ kits (from the re-releases of ten or so years ago) that I'll try to build closer to stock, yet still reinforced a little. And basically, what I described in the earlier message is what I'm going to do. thicker walled motor mount, gussets, and I'm looking for a lighter way to reinforce the fins.
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  #7  
Old 07-11-2010, 09:33 AM
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sandman sandman is offline
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Quote:
Originally Posted by Royatl
I should mention that MY old Maxi-Brute HJ, the one I originally built in 1979, was modified with a conversion kit I got from FSI to be able to use their F100 and E60 motors. It was nothing more than a motor mount tube (for FSI motors... unlabeled aerotech motors barely fit) and two centering rings that were basically 1/8" particle board! I flew it a few times on F100 motors with no problem, but the fins kept getting damaged with every landing. In 1990 I cut open the boat tail and epoxied four 3/8" pieces of balsa to the motor tube that served as pylons for my carved balsa fins, covered with silkspan and epoxy (replacing the vacuformed plastic ones). I flew it a number of times with F100 and some 24mm Aerotech motors.

I've got a couple spare HJ kits (from the re-releases of ten or so years ago) that I'll try to build closer to stock, yet still reinforced a little. And basically, what I described in the earlier message is what I'm going to do. thicker walled motor mount, gussets, and I'm looking for a lighter way to reinforce the fins.


Here's how I reinforced my HJ fins with very little added weight. This also works for the Maxi V-2 and the Saturn V fins.

With solvent cement, glue one half of the fin shell directly onto a full size 0.02" sheet of styrene plastic , either Plastruct or Evergreen brand. line up the leading edge along the edge of the sheet.

When that is set and dry cut the the fin carefully along the other three sides. Sand the edges nice and even.

Line up the other fin half and glue it onto the first with the styrene sheet between them.

Nice and strong and all you have added is one sheet of plastic to each fin.
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Old 07-11-2010, 10:52 AM
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stantonjtroy stantonjtroy is offline
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There's a great article on RP about uping the power and strength. Worth a look: http://www.rocketryplanet.com/content/view/2584/38/
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  #9  
Old 07-11-2010, 11:23 AM
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Quote:
Originally Posted by stantonjtroy
There's a great article on RP about uping the power and strength. Worth a look: http://www.rocketryplanet.com/content/view/2584/38/


yes, but that's vast overkill for what I want to do.
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  #10  
Old 07-11-2010, 12:04 PM
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sandman sandman is offline
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Quote:
Originally Posted by Royatl
yes, but that's vast overkill for what I want to do.


My method add strength to the weakest part of the model, the fins.

If you want to "bullet proof" it, start with a different kit!

When finished she'll still fly on a D12.
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