Alpha III motor loose

[Patternflyer]

Hello everyone! Getting back into rockets after a 35 year hiatus. I just bought a starter set with an Alpha III and completed it in 2 days. I installed an A8-3 motor in it and the motor slides fore and aft approximately 3/32” very loosely. Shouldn’t this be a snug fit? And if not, how much play is considered safe? If I shake the rocket in my hand, you can hear the motor clanking as it slides up and down within the engine hook. My concern is it slamming up and down during launch and ejection and wearing out the motor mount. Thoughts???
Thank you!

 

[ThirstyBarbarian]

I don’t think that small amount will be a problem. But if you don’t want it to move, I’d push it forward and then put a wrap of tape around It and the hook.

 

[Ronz Rocketz]

Or wrap masking tape around the motor to add some friction. The hook keeps the motor from moving forward and the block keeps the hook from moving forward, so unless you forgot to add glue to the block, you’re good. You’ll find out quickly after ignition if the motor ejects out the NC and chute.

If you used a motor retainer instead, that’s a different matter.

 

[Back_at_it]

Not going to hurt a thing. The newer style engine hooks are longer than the old so the motor moves around.

Like others have said, if it concerns you, put a wrap of tape around the motor but I honestly wouldn't bother. BTW, welcome back to the hobby.

When I returned a few yrs back I started building all of my old favorites. Some of them wouldn't stand on their own due to fin design if I used a motor hook. For these rockets I simply used a thrust ring (motor block) and friction fit the motors for launch. Works prefect and the rockets can now sit up on their own.

 

[BEC]

Agreed, that's not going to be an issue unless you put dozens of flight on it. By the way, welcome to TRF and a warning: the rocketry bug bites harder the second time. Heads up!

rklapp: the Alpha III doesn't have a motor block. Just the top of the hook to retain the motor and act as a thrust block, though I usually add one when I put together one.

 

[Ronz Rocketz]

Agreed, that's not going to be an issue unless you put dozens of flight on it. By the way, welcome to TRF and a warning: the rocketry bug bites harder the second time. Heads up!

rklapp: the Alpha III doesn't have a motor block. Just the top of the hook to retain the motor and act as a thrust block, though I usually add one when I put together one.

So what keeps the hook from pushing forward out of the MM tube? I may have built an Alpha in the 70s but don't remember.

 

[Patternflyer]

Not much other than the hook clipping into a small slot at the front of the tube. Here’s a picture from the manual.

Thank you all for your responses and thoughts concerning the motor. I just remember back in the day, it was always a chore to get the motor in there snug enough to get the clip over the nozzle. I’ll probably wrap some tape around the motor and the hook. At least that will alleviate it from slamming forward on launch.

 

[BEC]

So what keeps the hook from pushing forward out of the MM tube? I may have built an Alpha in the 70s but don't remember.

Ah, the OP did exactly what I was going to do - show you a picture of the instructions.

One can glue a motor block in above the top of the hook....and in some models one is provided. But none is provided in current Alpha flavors. Or really ever, all the way back to the first K-25 Alpha. This is from 1965:

All Alpha IIIs (and IVs and VIs) have gone together as patternflyer's instruction picture shows, since the Alpha III appeared in 1971. In the case of all these plastic fin can Alphas, the fin can itself prevents the top of the motor hook from coming out of its slot in the motor tube more than a tiny bit.

 

[Ronz Rocketz]

Ah, the OP did exactly what I was going to do - show you a picture of the instructions.

One can glue a motor block in above the top of the hook....and in some models one is provided. But none is provided in current Alpha flavors. Or really ever, all the way back to the first K-25 Alpha. This is from 1965:View attachment 440771

All Alpha IIIs (and IVs and VIs) have gone together as patternflyer's instruction picture shows, since the Alpha III appeared in 1971. In the case of all these plastic fin can Alphas, the fin can itself prevents the top of the motor hook from coming out of its slot in the motor tube more than a tiny bit.

Does the hook butt up against the adapter ring (E)? Seems like since E goes over C, it prevents the hook from moving forward. Honestly, I've never done a fin can.

 

[Patternflyer]

The ring (E) slides over the end of the motor tube (C) on the outside. It then sits on top of the fin can (A) giving the rocket body more to slide onto. There is nothing inside the motor tube assisting the engine hook. Hope that made sense.

 

[Back_at_it]

After thinking about it I realized that I don't think I've ever looked at the instructions for an Alpha 3 but I recalled building one with my GF's nieces at their house and it had a thrust ring. I pulled a couple of the kits I have left from a bulk pack and sure enough.

 

[Patternflyer]

Very interesting how there is actually a difference and variation amongst kits. I noticed too that the body is different. Mine came with a solid black body whereas I see an orange end on yours. Wish I had known about putting in a motor block before I sealed everything up. Oh well, live and learn......... Thanks for checking on that! Good info!

 

[Antares JS]

Mine came with a solid black body whereas I see an orange end on yours.

Pretty sure that's just the nose stuck point-first into the tube for packing.

 

[Back_at_it]

Very interesting how there is actually a difference and variation amongst kits. I noticed too that the body is different. Mine came with a solid black body whereas I see an orange end on yours. Wish I had known about putting in a motor block before I sealed everything up. Oh well, live and learn......... Thanks for checking on that! Good info!

The nose cone is stuck in one end of the tube. Even if rockets don't come with motor blocks, I add them on all of my 13, 18 and 24mm rockets. On the 24mm kits I do extend the motor mount tube and place the thrust ring up further so I can fly the longer E motors. This also keeps the motor block out of the way should I want to run a AT motor that is a little longer.

 

[jimzcatz]

I'm sorry, I just can't let this one go. Did you really NOT see in the instructions where it says if motor is loose wrap masking tape around it for a tighter fit? And Motor Blocks? so 60's Been using Tape thrust rings since 4ever.

 

[Back_at_it]

And Motor Blocks? so 60's Been using Tape thrust rings since 4ever.

Seems unnecessary to do a tape ring every time when you can do a motor block once and be done but we all do things our own way.

 

[BEC]

Does the hook butt up against the adapter ring (E)? Seems like since E goes over C, it prevents the hook from moving forward. Honestly, I've never done a fin can.

View attachment 440772

Not quite. Here are pictures of the recent re-release Phantom, which is an Alpha III made with clear plastic parts. I'm holding it with a little desk lamp behind it to help illuminate. You can see that the upper centering ring doesn't quite make it down to the top of the motor hook.

In the second picture in particular you can see the gap that the OP was wondering about, as the plastic cutaway motor is all the way down against the bottom of the motor hook in this Phantom (and held there with some double-sided tape so that the half-motor doesn't fall out and get lost).



When I put together an Alpha III/VI or other similar models I will usually treat the motor tube slot with thin CA to toughen it up a bit, as I tend to fly a model many times. And I'll often add a motor block when one isn't provided.

After thinking about it I realized that I don't think I've ever looked at the instructions for an Alpha 3 but I recalled building one with my GF's nieces at their house and it had a thrust ring. I pulled a couple of the kits I have left from a bulk pack and sure enough.

View attachment 440786

Deleted my prior comment. Those do look like motor blocks, now that I've looked more closely. That's a surprise. By any chance can you read the production date on one of those kits? It'll be stamped into the sticker sheet, since those are relatively recent ones with the current orange/white 'chute.

 

[BEC]

I'm sorry, I just can't let this one go. Did you really NOT see in the instructions where it says if motor is loose wrap masking tape around it for a tighter fit? And Motor Blocks? so 60's Been using Tape thrust rings since 4ever.

And that would be where, exactly in this: https://estesrockets.com/wp-content/uploads/Instructions/001256_ALPHA_III.pdf (or the instructions or any other model with a motor hook)? Not having to mess with tape and friction fitting is the whole point of a motor hook....since the '60s. Since late 1965 in fact, when the K-25 Alpha first appeared in MRN.

 

[Back_at_it]

Those are AR-2050 centering rings, not motor blocks.

Hate to disagree. If you look close you can see they are actually the 5/20 centering rings that are used as motor blocks in the 18mm kits. It's hard to see in the first pic as the smaller on is laying inside the 2050 but it's clear on the second pic.

 

[Back_at_it]

And that would be where, exactly in this: https://estesrockets.com/wp-content/uploads/Instructions/001256_ALPHA_III.pdf (or the instructions or any other model with a motor hook)? Not having to mess with tape and friction fitting is the whole point of a motor hook....since the '60s. Since late 1965 in fact, when the K-25 Alpha first appeared in MRN.

Exactly. The instructions mention adding tape to the nose cone if loose. Not the motor.

 

[BEC]

Hate to disagree. If you look close you can see they are actually the 5/20 centering rings that are used as motor blocks in the 18mm kits. It's hard to see in the first pic as the smaller on is laying inside the 2050 but it's clear on the second pic.


View attachment 440810View attachment 440811

Sorry my edit to the prior post didn't get there before you did....you are right and I am surprised. Can you read the date on the sticker sheet through the bag on one of those? I'm just curious when those were packaged as I've not seen a motor block in any Alpha IIIs from the first ones (early 1970s to current) but I haven't gone looking at them carefully either. I've been much more focused on K-25/1225 Alphas rather than K-56/1256 Alpha IIIs and their near-identical descendants (Alpha IV, Alpha VI, Rocket Science Starter Set rocket, etc.)

 

[Patternflyer]

I'm sorry Jimzcatz, but I couldn't find it anywhere in the manual about wrapping the motor. My whole intention in this posting was concerning the fore/aft movement that the motor could experience during launch and ejection. I'm not sure how much this "slamming" effect may have over the long term duration of the hook and motor mount. I fully understand how it would survive in the short term, however. I've been out of the hobby for over 3 decades and vaguely remember that it used to take some effort to squeeze the motor into the engine hook. Apparently, from what I've read on this thread, Estes has since lengthened the engine hooks, which now allows for that movement.

I was hoping that someone may offer advice, maybe wrap the motor and hook together with tape, insert a spacer in front of the motor, or something along those lines. This thread quickly diverted to the integrity of the Alpha III regarding putting a motor block ahead of the hook. Albeit, that is a great idea, and had I thought of it, I would have added one prior to final completion, but that honestly would have no effect on what's going on within the engine hook.

I googled every possible way about this situation of the motor sliding up and down within the hook and found nothing, so I joined this forum in order to ask such questions. I truly appreciate those that offered sound advice and constructive criticism and will take that knowledge forward with me.

I do find it odd that Estes no longer offers a motor block in the kits nor do they mention it in the instructions. If I ever build a similar model in the future, I will add one on my own if not supplied by Estes, so I thank you all for bringing that to my attention. And lastly, the decal sheet on my kit had the date of: 03/24/20

 

[Back_at_it]

Can you read the date on the sticker sheet through the bag on one of those?

I tried to get a pic but it won't focus on the date stamp even out of the bag but it reads 05/19/11.

 

[BEC]

I'm sorry Jimzcatz, but I couldn't find it anywhere in the manual about wrapping the motor. My whole intention in this posting was concerning the fore/aft movement that the motor could experience during launch and ejection. I'm not sure how much this "slamming" effect may have over the long term duration of the hook and motor mount. I fully understand how it would survive in the short term, however. I've been out of the hobby for over 3 decades and vaguely remember that it used to take some effort to squeeze the motor into the engine hook. Apparently, from what I've read on this thread, Estes has since lengthened the engine hooks, which now allows for that movement.

I was hoping that someone may offer advice, maybe wrap the motor and hook together with tape, insert a spacer in front of the motor, or something along those lines. This thread quickly diverted to the integrity of the Alpha III regarding putting a motor block ahead of the hook. Albeit, that is a great idea, and had I thought of it, I would have added one prior to final completion, but that honestly would have no effect on what's going on within the engine hook.

I googled every possible way about this situation of the motor sliding up and down within the hook and found nothing, so I joined this forum in order to ask such questions. I truly appreciate those that offered sound advice and constructive criticism and will take that knowledge forward with me.

I do find it odd that Estes no longer offers a motor block in the kits nor do they mention it in the instructions. If I ever build a similar model in the future, I will add one on my own if not supplied by Estes, so I thank you all for bringing that to my attention. And lastly, the decal sheet on my kit had the date of: 03/24/20

No worries. Some of us tend to get stuck in the minutiae.

I will say that after a couple dozen flights there will likely be some slop as the hook itself will be able to move back and forth as the top of it has enlarged the slot you originally cut for the top of the hook. As a practical matter, as long as it doesn't pull all the way out the model is still flyable. I've never had that slot get enlarged in the forward direction—even on models with around 100 flights (I've had a couple of those, though neither were Alpha IIIs).

It seems the ejection charges cause more trauma to the motor tube/top hook slot than the thrust of the motor does. And as you point out, adding a motor block really doesn't address this wear/failure mode anyway. And as I sit here thinking of this, that there is as much fore/aft slop between the hook and the motor could certainly exacerbate this happening. Hmmmmmmmmm.

Back_at_it's Alpha IIIs from a recent bulk pack are surprising to me as I noted before. I've not seen a motor block in an Alpha III kit or instructions, going all the way back to the beginning. Here's one of the first Alpha III instruction sets, and it shows pretty much all the same thing, but with more words and fewer pictures:

 

[BEC]

I tried to get a pic but it won't focus on the date stamp even out of the bag but it reads 05/19/11.

Thanks. So it's a little older than I'd guessed but.....still mysterious. You'd have to open one to answer this question, so feel free to not bother, but....do the instructions with those kits call out and use the motor block? As I say, I've not seen that before in an Alpha III and the current versions, both posted on the Estes web site and as mentioned by the OP just above, don't.

 

[Back_at_it]

I was hoping that someone may offer advice, maybe wrap the motor and hook together with tape, insert a spacer in front of the motor, or something along those lines. This thread quickly diverted to the integrity of the Alpha III regarding putting a motor block ahead of the hook. Albeit, that is a great idea, and had I thought of it, I would have added one prior to final completion, but that honestly would have no effect on what's going on within the engine hook.

Pattern, You can still add a motor block now. I've done this with countless rockets I've restored. The motor hooks from Quest and Custom use to be really flimsy and would fail all the time. Every time I get my hands on one to restore I do this.

All you will need to do it cut a slot about 1/4" wide in the block so that it will slide up past the upper end of the hook. When you do this you will want to make sure you get the glue up as high as you can in the motor tube as you don't want to get it block or the spacer you use to push it in stuck in the tube.

With that said, I recommend using an old motor as the spacer. Cut the gap in the ring, Make it about 1/4' wide. Add glue into the upper part of the tube. Align the ring so the gap is lined up with the motor hook and use an old motor to push it in place.

Here is one I did on a Quest Oasis. I have since taken the motor hook out of the rocket all together as it prevented the Oasis from standing on its fins. I just friction fit the motor now to prevent it from blowing out the rear on ejection.


.

 

[Patternflyer]

BEC and Back at it, thank you for your thoughtful responses and ideas. What do you think about me glueing in a 1/16 or 3/32 thick spacer ring up against the engine hook on the inside of the motor tube? This will accomplish 2 things (hopefully). First of all, it would eliminate the slop in the motor sliding up and down, and secondly, it would help reinforce the hook so it won't wear that slot out any bigger.

 

[BEC]

Pattern, You can still add a motor block now. I've done this with countless rockets I've restored. The motor hooks from Quest and Custom use to be really flimsy and would fail all the time. Every time I get my hands on one to restore I do this.

All you will need to do it cut a slot about 1/4" wide in the block so that it will slide up past the upper end of the hook. When you do this you will want to make sure you get the glue up as high as you can in the motor tube as you don't want to get it block or the spacer you use to push it in stuck in the tube.

With that said, I recommend using an old motor as the spacer. Cut the gap in the ring, Make it about 1/4' wide. A d glue into the upper part of the tube. Align the ring so the gap is lined up with the motor hook and use an old motor to push it in place.

Here is one I did on a Quest Oasis. I have sense taken the motor hook out of the rocket all together as it prevented the Oasis from standing on its fins. I just friction fit the motor now to prevent it from blowing out the rear on ejection.


.View attachment 440822

That's a slick idea. I like it. And it will have the added benefit (if using a spent motor as the spacer) of placing the motor block down a bit relative to the hook end, potentially getting rid of the slop that started this discussion.

 

[BEC]

BEC and Back at it, thank you for your thoughtful responses and ideas. What do you think about me glueing in a 1/16 or 3/32 thick spacer ring up against the engine hook on the inside of the motor tube? This will accomplish 2 things (hopefully). First of all, it would eliminate the slop in the motor sliding up and down, and secondly, it would help reinforce the hook so it won't wear that slot out any bigger.

Or do as back_at_it suggested just above, which I suspect you're reading now since we all three seem to be posting in this thread at once and are a little behind one another in responses....

I'll get away from the computer now and let things settle a bit.

 

[Patternflyer]

Back at it, that is a great idea! If I do that and insert a spacer in the inside of the hook, I would be sandwiching the hook and and really beefing it up.

Yes, we are all posting at the same time, which makes for some fun back and forths. LOL Good stuff guys! Much appreciated!