No Forward Engine Block Whatsoever---Wish Me Luck!!

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tfrielin

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This weekend, after a two year hiatus, I will finally be launching my rockets again for a Mothers' Day Weekend family celebration. Down at the farm. (Any excuse is a good excuse!)

First launch for my new Doorknob and my Super Big Bertha.

One thing they have in common is---No Forward Engine Block!

Ok, I followed the masking tape wrapping of the engines. And screwed them into place with that 21st Century design rear engine mount, so I'm hoping for the best.

But, still, something in me worries that the engines will shoot themselves through the rocket instead of staying put and propelling the rockets. I kind of feel like John Young and Bob Crippen on the first launch of Columbia--Is this really going to work???

So, wish me luck. and anyone with experience with rockets With No Froward Engine Blocks (!!!!) please post back to allay my fears.

Thanks. Will report back with how it goes...
 

Bat-mite

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Composite motors have a built-in thrust ring and don't require forward retention. I assume you are using BP motors? You can create a thrust ring with tape, or friction fit, as long as you get absolutely no wiggle.

But please, if you are unsure if the motor will stay in the rocket -- DON"T LAUNCH.
 

heada

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Masking tape rings work very well. I've used them on APCP up to G40 motors and others have used them well into HPR ranges.

Good luck, welcome back and have fun
 

tfrielin

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Composite motors have a built-in thrust ring and don't require forward retention. I assume you are using BP motors? You can create a thrust ring with tape, or friction fit, as long as you get absolutely no wiggle.

But please, if you are unsure if the motor will stay in the rocket -- DON"T LAUNCH.
Yes, I'm using an Estes BP engine--an F 16-6 for each on them.

Got good tight fits. No wiggles. In fact, I had to sand the engine mounts to rid them of excess epoxy just to get the engines in to begin with.

So, maybe they will stay in place as advertised??
 

neil_w

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Yes, I'm using an Estes BP engine--an F 16-6 for each on them.

Got good tight fits. No wiggles. In fact, I had to sand the engine mounts to rid them of excess epoxy just to get the engines in to begin with.

So, maybe they will stay in place as advertised??
If you have a good tape ring you'll 100% be totally fine and dandy.

If you have doubts, post a picture of your taped-up motor here (before insertion). Good to prep those in advance anyway, no point fussing with it at the field.
 

Daddyisabar

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Deleting the engine block and hook is your first step into a much larger world. You must be cautious. Keep your mind on where you are at, what you are doing.
 

Scott_650

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I generally leave the block out of 24mm rockets too if they have screw on retainers - not likely I’ll use a longer reloadable motor but I might. Tape thrust rings work fine.
 

jimzcatz

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I really don't understand your concerns. I personally have used tape rings on motors up to L750 and seen pictures of Master Frank Kosdon using it on an O motor. Yes it works, its all we had back in the day.
 

samb

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No worries ! :). You have all these testimonials here and in the Estes Doorknob Body Tube thread, not sure what else will make you feel better about it until you launch that puppy.
I’m jealous, Mother’s Day is a hard “no fly” day for me. :)
 
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Blast it Tom!

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I used masking tape a lot when I was a kid in the late 60's. I had only one dramatic experience with the Astron Starlight. As it climbed gracefully into the heavens, I thought how dramatic the fire from the engine was, much more so than usual - must be that ring around the rear end. Well, the engine didn't move. Turns out I'd forgotten to glue the engine MOUNT in, so centering rings and all went forward and the dramatic fire was, of course, the aft end of the body tube blazing away. Well, it did look good while it lasted! And it was tight enough to blow out the parachute, so it was recovered. Never flew it again, though, and it was lost with all my childhood rockets.

Today I'd just patch in a new section of body tube and it's off to the races again... So there's your cautionary tale!
 

tfrielin

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I used masking tape a lot when I was a kid in the late 60's. I had only one dramatic experience with the Astron Starlight. As it climbed gracefully into the heavens, I thought how dramatic the fire from the engine was, much more so than usual - must be that ring around the rear end. Well, the engine didn't move. Turns out I'd forgotten to glue the engine MOUNT in, so centering rings and all went forward and the dramatic fire was, of course, the aft end of the body tube blazing away. Well, it did look good while it lasted! And it was tight enough to blow out the parachute, so it was recovered. Never flew it again, though, and it was lost with all my childhood rockets.

Today I'd just patch in a new section of body tube and it's off to the races again... So there's your cautionary tale!

Thanks for the, uuhh, encouragement, Tom.

From all the posts here I'm now confident this will work as advertised. And, yes, to another post---I do have the screw in retainer in place.

I do have some experience with composite motors on a Nike Smoke and I do love it that the engine itself has that built-in ring at the bottom that makes for a snug fit. Will also be launching my Nike Smoke, too. Got four composites--F and a G engines.

Hoping for a day of calm winds and no hungry trees!
 

jimzcatz

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Not all hp/composite motors have built in thrust rings. I have several single use motors that do not as well as reload hardware..Yes,it's probably older than most of you.
 

Blast it Tom!

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You know, it's the forward missing part that kinda gets me. I used tape to keep the ejection charge from blowing the motor out the back. I can't be 100% positive (I'm not a proton...) but I think a thrust ring was always a standard part of an engine mount. Something for the motor to push against that isn't relying on friction. Figure if you need only 3 lb of force to push the motor in, and you have a motor with 12 lb of thrust, very likely there will be some relative motion between the motor and the rocket shortly after ignition. So yessir, I may be out of my league here, but that's my simple take.
 

jimzcatz

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A tape thrust ring is a wrap of tape around the very bottom of the motor, usually 1/4 inch tape. Wrap several wraps so motor can't move forward. Yes, it will hold. This is not friction fit, which is just to keep the motor from falling out
 

Blast it Tom!

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A tape thrust ring is a wrap of tape around the very bottom of the motor, usually 1/4 inch tape. Wrap several wraps so motor can't move forward. Yes, it will hold. This is not friction fit, which is just to keep the motor from falling out
Ah, thanks! I'll get my coat...
I keep learning new things from all you more experienced folks! I bet he'll be just fine!
 

Antares JS

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(...) I think a thrust ring was always a standard part of an engine mount. Something for the motor to push against that isn't relying on friction.
When I first started in rocketry in the 90's, Estes kits did not come with thrust rings, relying on the part of the motor hook that sticks into the tube to prevent the motor from shooting forward. This usually worked okay but a CATO could easily send your motor shooting through the rocket and it wasn't as durable as a thrust ring. I've been adding thrust rings to several old rockets that needed repairs because the hooks weren't cutting it on their own.
 

Blast it Tom!

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When I first started in rocketry in the 90's, Estes kits did not come with thrust rings, relying on the part of the motor hook that sticks into the tube to prevent the motor from shooting forward. This usually worked okay but a CATO could easily send your motor shooting through the rocket and it wasn't as durable as a thrust ring. I've been adding thrust rings to several old rockets that needed repairs because the hooks weren't cutting it on their own.
Yes, I think I noted that from you elsewhere - and on that advice, I'm adding them to the MPC "Duck Dodgers" rockets I bought for the grandkids, as I'll be putting them up on Quest D16's. Thanks!
 

Spitfire222

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1) Materials:

2) Seven or eight wraps of tape wrapped around the bottom 1/4" of the motor:
3) Trim off the excess:

4) Insert motor in rocket:

5) Screw on retainer:

6) Light it up
Excellent job with providing the photos. I feel like there was the possibility of some confusion with differentiating between a tape thrust ring, tape friction fit, and taping the motor to the tube.

For the thrust ring method, you can even skip a step and use 1/4" masking tape to not need to trim anything!
 

Back_at_it

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The tape ring works most of the time when done right but I have seen it fail more times than I care to mention. Obviously this varies by individual and the failures come when someone does it wrong.

You need to ensure that the tape wrap is TIGHT to the motor and that you use enough of it. I personally prefer clear packaging tape if I'm going to do this.

Personally, I use a motor block everything that I could ever possibly fly on a 13, 18, 24 or 29mm motor. The only thing I do differently is that I place that motor block further up the motor tube for my 24 and 29mm rockets. Even if the rocket isn't designed to fly on the longer 24mm E & F motors. I place the motor tube at that location just incase I want to do it someday.

Putting them that far up keeps them out of the way of any 24 or 29mm composite I would want to use.
 
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samb

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The tape ring works most of the time when done right but I have seen it fail more times than I care to mention. Obviously this varies by individual and the failures come when someone does it wrong. ...
I’m really surprised to hear this. That won’t make the op happy since some of us have been telling him for months that tape thrust rings are pretty foolproof. I’m trying to imagine what the failure mode might be. Not enough wraps ?
 

Lee

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First launched my new door knob just last week. I used the 29/24 Este adapter - which has a thrust ring - with 24mm engine. Hasn't been painted yet, just primer. My plan was to use the smallest motor (D) for first launch, then move up to E & F. It was a slow moving, realistic flight to perhaps 400 feet. On decent there was considerable sway. Landed on a soccer field less than 100 feet from launch site. Upon retrieval I saw that one of the balsa fins was cracked. I had filled the grain and left the fin corners full thickness for strength. I was concerned about the landing risk since the fins are right there at the aft end.

I am now reinforcing the fins and will probably trim the bottoms so that the motor MMT bears the brunt of landing. Will also cut an over flow hole in the parachute to minimize sway.
 

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CalebJ

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When I first started in rocketry in the 90's, Estes kits did not come with thrust rings, relying on the part of the motor hook that sticks into the tube to prevent the motor from shooting forward. This usually worked okay but a CATO could easily send your motor shooting through the rocket and it wasn't as durable as a thrust ring. I've been adding thrust rings to several old rockets that needed repairs because the hooks weren't cutting it on their own.
That's been hit or miss since at least when I was a kid playing with model rockets in the 80's. There were plenty of kits then that had thrust rings and now that don't.
 

Back_at_it

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I’m really surprised to hear this. That won’t make the op happy since some of us have been telling him for months that tape thrust rings are pretty foolproof. I’m trying to imagine what the failure mode might be. Not enough wraps ?
Generally the issue is someone doesn't pull it tight around the tube or doesn't use enough wraps to keep the motor from slipping into the tube. I've also seen a couple of failures where guys would use any old dried up masking tape that has been in range box for years. It works if you do it right. Problem is, beginners that don't have someone there to show them the right way the first time generally are the ones that make the mistakes.
 

samb

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Generally the issue is someone doesn't pull it tight around the tube or doesn't use enough wraps to keep the motor from slipping into the tube. I've also seen a couple of failures where guys would use any old dried up masking tape that has been in range box for years. It works if you do it right. Problem is, beginners that don't have someone there to show them the right way the first time generally are the ones that make the mistakes.
Ok, I never thought wrapping tape around a tube would be that difficult. I guess I’ve been flying with a club too long. Anybody who wants it gets my 2 minute expert level demo. I hope the op got that from Neil’s pictorial in this thread.
The Doorknob and Super Big Bertha specify a tape thrust ring and include no internal ring. I wonder if they’ve gotten any feedback on failures ?
 

jimzcatz

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If done correctly a tape thrust ring will never fail. Physics prohibit this. In over 30 years of using them I have never seen them fail. If they have failed it is most definitely user error or inferior tape
 

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