Aerotech/Estes Question

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flying_silverad

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Can I use an Aerotech D21-4 in place of any of my Estes D engines without modifying the engine mounts? Take for example my Alpha III, could I insert one in place of a D12-3 without any modification?
 
The AT D21 is a composite and is 18mm in diameter, so you will need to build an adapter for the 24mm mount. The D21 is a cool replacement for an Estes 18mm motors :)
 
You could do a quite simple, removable modification. I'm guessing you want to try the AT D21 but still be able to use Estes D12.

If you took a BT50 coupler and cut it to 70mm (length of motor) you could then put an 18mm mount inside the coupler with some centering rings.

You could then insert this into the 24mm mount on your Alpha as you would a motor. The D21 will then go inside the 18mm mount in the coupler. Then if you wanted to use it for a D12 again just remove the coupler thing (as you would a motor) and its back to normal.

Hope that helps.
 
Another cheap method of making a 24/18 adaptor, that has been mentioned here before, is to take a used 24mm Estes D motor casing and clean out the inside of the tube thouroughly. At one end of the cleaned and empty 24mm casing, glue an 18mm engine block. The 18mm motor will fit right inside. Be sure to friction fit the motor since you will not have any positive motor retention.

This method also works when going from 18mm to 13mm.
 
So if I didn't want to change the mount to allow for the 18mm, could I slip a AT "E" series motor in the estes mount without any modification to the mount?
 
Yup, the E15 and E30 work great as a replacement for the D12. Just make sure you're ready to walk that much further to retrieve them :) I haven't used one, but AT also has an F (F21?) that fits in place of the Estes E9.
 
Originally posted by flying_silverad
So if I didn't want to change the mount to allow for the 18mm, could I slip a AT "E" series motor in the estes mount without any modification to the mount?

In terms of motor sizes and fitment, the answer is yes. An AT E15/E30 is 24mm in diameter and will fit the Estes "D & E" sized motor mounts. The exception is a model that is constructed with a long Estes E sized motor hook. You'll need to be sure and use the adapter that comes with the kit for the shorter D's and AT E15/E30.

The only caution I and others will give here is that you will encounter a threshold or breach in construction rigidity. A heavy Estes model relying on a motor hook may eventually fail with a high thrust motor. Other components to reinforce are items such as the fins. Under high stress and thrust, you might have a fin tear away or shred. The Estes cardstock centering rings face the possibility of binding under high power.

Usually, when I build an Estes model, I overbuild it so that I can put higher thrust motors in them. Heck, AT has an F21 that will fit into a 24mm MMT!!! Imagine sending your Maxi-Alpha on an F21! Of course, there is a careful balance between weight and rigid construction, so use your best judgement.

Good luck and let us know if that AT E puts your Alpha up high.
 
I agree and disagree :) About the stock kits being able to take the larger motors. IMHO, if you build well using normal techniques (fins are straight, you add fillets, etc) most Estes 3/4FNC rockets will handle one step of motor upgrade. That is a C powered rocket will handle the AT D21, and a D powered rocket will handle an E15. I said 'most' because I am not that familiar with the current fleet. Note also I said 3/4FNC, some of the exotics with odd and large wings may not handle it. Examples that work well with E's are the Big Daddy and Mean Machine.

Where I agree, is that the composite engines will deteriorate an Estes rocket quickly. Oddly, in my experience, it is not due to the higher thrust, but due to a more enerjetic ejection charge, and that the delay grains burn after the ejection charge has fired. A small diameter rocket, BT-50 and smaller, runs the risk of structural problems due to charring. I had an original Sizzler that was Bt-50 based and after one flight on the D21 the rocket body was bubbled (the tube not the paint). Some people add liner tubes and the like to avoid this problem. The other thing is the elastic chock cord doesn't hold up to well with composites. A short piece of Kevlar twine as a leader fixes this problem.

BTW, eugene, this was an important point to bring up, rather than just my original short answer. Good input, man. Unfortunately, the length of my answers are often proportional to haow busy I am at that moment. :(
 
I'll add one more thing: If you are using the AT 24mm RMS (Reloadable Motor System), don't forget that you have an opportunity to "tune" or "adjust" the ejection charge power. rstaff brings up an excellent point about ejection charge power with the composite AT motors.

I found out the hard way the first time I substituted an AT D15 24mm RMS for an Estes D12-5. I used all the powder in the little cup provided with the RMS, and it blew the nose cone and parachute out of the rocket with such force that it broke the elastic shock cord. Fortunately the body tube was light enough that it fell to the ground with no damage.

At any rate, if you have a small body tube, you might want to reduce the amount of black powder you use in the ejection charge with the RMS motors.

Now... as far as the ejection charge power on the single use AT composite motors, .... I've never tried to "adjust" those, and I don't know if doing so would be a violation of TRA or NAR code from the standpoint of altering a single use motor. I'm sure one of our TRA / NAR code gurus can chime in here and tell you.

- Ken
 
Originally posted by rstaff3
Examples that work well with E's are the Big Daddy and Mean Machine.

with a 29mm mount, the mean machines like F23 econojets alot. but stay away from F50's

Scott McNeely
 
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