My son recently assembled an estes asteriod hunter. For his second rocket ever built, I'd say he did a great job. While I was painting it I discovered that the engine hook is 1/4" in front of the engine block. I think this will cause some problems. 1: The paper engine mount tube is likely to rip during launch. 2: The extra 1/4" of engine sticking out the rear of the rocket will cause some balance issues? My thoughts on a solution were to glue in another engine block right in front of the hook. I would have to cut a small portion of it to slide past the hook, but it could be done. Next, put just a little bit more clay in the nosecone. This is the part that he is not in agreement with me about, as he thinks the rocket is already heavy enough. Any thoughts on this issue are appreciated as we have a club launch in two weeks. Thanks to all.......
Alec The Bubamech

Should be fine as is. Does the motor hook go under the rings, or was it taped to the mount? That would keep it from ripping out.

kj

I did not realize before that you were one of ours - a Dallas area rocketeer. Hope to see you at Frisco.

#1 should not happen as the motor will be pushing against the engine block instead of the hook.

Is the engine block in the proper location or is the engine hook? They cannot both be. If the engine block is in the proper location, your motor will be as well and there will be no balance issues. If the hook is in the proper location and he installed the block behind instead of in front of the front end of the hook, then you may have to add to the nose weight. Maybe John Boren (id Jumpjet) from Estes will post his opinion on this.

One more issue to address is how to keep the motor from sliding out when the ejection charge goes off. You can bend the end of the hook to do that or your can wrap some masking around the motor to friction fit it. With the plastic nozzle, I do not think you will have enough room to do it by wrapping tape around the motor and the hook.


Bill

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I think my description was a bit off. The hook is behind the block. I hope the drawing helps. He put so much work into this rocket. I would hate to see anything less than a perfect launch and recovery. Thank you for any advice.

Attached Thumbnails

 

It should work as is. Most Estes kits tend to be a bit overstable. Many of the Estes kits that I built back in the the 70s and 80s did not have a thrust ring in front of the motor hook. Several of them are still flying today.

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'Til next time,

Mike Toelle

NAR 31692 L1

SAM 0373

Many Estes kits do NOT have a large margin of stability, so I wouold simply insert a motor and push hard to force the hook to move forward until it stops at the motor block. Yes, it will tear the inside of the motor mount tube a tiny bit, but that is not important. Having the motor at the correct location to ensure stability is most important.

Your other option is to add clay weight inside the nose cone. That usually leads to early shock cord failure (heavier nose cone cuases more stress on short shock cord).

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-Fred Shecter NAR 20117 (L2)
Southern California Rocket Association, NAR Section 430

The Asteroid Hunter is a short and stubby rocket. I suspect it does have that safety margin.


Bill

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It is well past time to Drill, Baby, Drill!

If your June, July, August and September was like this, you might just hate summer too...

Please unload your question before you ask it unless you have a concealed harry permit.

: countdown begin cr dup . 1- ?dup 0= until cr ." Launch!" cr ;

Give a man a rocket and he will fly for a day; teach him to build and he will spend the rest of his days sanding...

No, I would not do that. Or at least, not only that. Tearing the motor tube will eventually lead to the hook ripping out at ejection.

The best way out of this is to try to file off the forward end of the hook. Then try to work the hook loose and remove it, or cut off the back part. Then friction fit the motor for flight.


Bill

__________________
It is well past time to Drill, Baby, Drill!

If your June, July, August and September was like this, you might just hate summer too...

Please unload your question before you ask it unless you have a concealed harry permit.

: countdown begin cr dup . 1- ?dup 0= until cr ." Launch!" cr ;

Give a man a rocket and he will fly for a day; teach him to build and he will spend the rest of his days sanding...

In the past, some kits did not include the forward motor block (ring). The motor's thrust was transferred entirely via the tang on the hook.

Rather than trying to modify something already built, if you are concerned about it, add a tape thrust ring on the back end of the motor to push against the motor tube.

Insert the motor into the hook, then draw a pencil line around the end of the motor at the tube, then apply three wraps of 1/4" wide (or 1/2" wide) masking tape to the motor at the line. This should help keep the hook from doing all the work.

It ought to look something like this when you're done.

Doug



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I still think it will work fine as is, but Doug's suggestion is a good one if you're worried about it.

kj