New and Rocket #1 brings questions

[TwoWalks]

I assume I am like many others - I seen the show on discovery and it lit a fire under me. Last week I went to the Hobby store and returned home with three kits.

I selected the kits based on skill level 1,2 & 3 as well as size and other considerations. The three kits I chose are:

1. Estes Fat boy skill level 1
2. Estes Black Brant 2 skill level 2
3. Quest Tomahawk skill level 3

Ok, the saga begins:
Two days ago began work on the Fat Boy as well as the Black Brant. The Fat boy is now together and the fillets have been done as well as the sanding and it sits waiting for the first coat of primer. The BB2 is a partial and is waiting for me to build a fin jig so I can hold the fins in alignment while the glue dries. All is going well, but the two kits together have brought forth a question on motor mounts.

The FB has a clip and I have seen this on all the sites I have read so far. The BB does not have a clip but has a motor block in the back of the tube. Question is: How do these differ in performance? Is one better than the other? Is there something that tells you which style to use or is it just a preference thing?

Let the education begin

 

[jetra2]

Well...

What you have in the Fat Boy is what's called "Positive Motor Retention." Basically it means that the motor ejects the parachute, it won't go flying out the back. That is the hooks job. On the BB2, the ring is called a "thrust ring." It keep the motor through flying the the middle of the rocket as it burns, so that it doesn't burn up the inside of your rocket...which as you would imagine, is VERY VERY BAD! What you want to do when you fly your BB2 is wrap a little bit of masking tape on the motor so that you can only pull it out after applyinga good deal of force. Be careful when you do that so that you don't crimp the body tube or anything. What I usually do is put one wrap of masking tape around the motor (overlapping less that 1/2 inch) then insert the motor in the MMT tube, and finally put one or two wraps of masking tape at the end of the motor, at the motor tube. I have never had a failed ejection this way.

500th post!

Jason

 

[powderburner]

jetra's explanation is good, the following is not to dispute anything said----

I think the basic (traditional) black-powder motor mount is a tube with a blocking ring glued in place up front. This is minimum weight, minimum parts (and more profit for the kit maker), and the way things were done back in the good 'ol days. Problem was, you had to use judgement to select how much tape to wrap around the motor case to get a good friction fit. Too much tape and the motor could get stuck (motor case expands, and tape gets gooey). Too little tape and the motor pops out the rear instead of the parachute out the front. Get it just right and everything works fine.

It doesn't take a rocket scientist to see that this was too challenging for beginning rocketeers (with no experience to judge how to tape up their motors). Someone invented motor clips that hook over the front and rear of the motor case; you glue the front part to the motor mount and let the rear free to flex out of the way to change out the motor. Many people continue to use a thrust block ring at the front, which seem redundant until the little tab at the front bends or breaks, then that thrust ring comes in pretty durn handy. Clips (or hooks) hold the motor case pretty well, but occasionally will have problems at ejection when the clip flexes back out of the way and lets the motor spit out. (This can be prevented by taping around the nozzle and clip, holding the two together.)

Which one is better? For sport and general flying, go with a clip (with or without a thrust ring). For competition, you probably want to be careful of vehicle weight and you may only want to use a ring.

One other type of retaining clip is a wire clip that forms a complete "U" under the edge of the motor. These are made of tempered wire (like the music wire you can find at your local hobby shop, NOT the soft iron wire at the hardware store) about the size of paper-clip wire (or slightly smaller). The tops of the "U" clip are bent inward to go through the body tube and catch the front of the motor. The length of the sides of the "U" are the dimension necessary to hold on to your selected motor. The width of the bottom of the "U" is enough to hook securely under the nozzle end of the motor casing, and to spread the sides of the "U" to they nestle into the roots of two fins. You glue the front of this clip into the fillets, and leave the rear half free to flex (like the flat clip you are already familiar with). You may also want to tape this clip to the nozzle to make sure it doesn't let go.

High-power motors are another animal entirely, and use many more means to secure the motor case.

 

[powderburner]

Lots of the Estes kits now include little plastic pieces that 'lock' the motor in place. These are great--- for the first few flights, at least. If your rocket lands on the concrete, they may not survive. If you are clumsy (like me) and your launch site has tall grass (like mine) you may drop that little bitty piece and lose it. If you fly your model rocket more than about ten times, you may melt it, or distort it out of shape when it gets warm and soft. Other than that, Mrs. Lincoln, how did you like the play?

You can always continue to fly model rockets that were originally designed with turn-n-clip motor locks. You just go back to the old-style way of taping the motor casing with masking tape for a snug, almost-tight fit (DO NOT USE CELLOPHANE TAPE for this).

 

[raw9jr]

For the Black Brandt don't go with the clip. The plastic boattail would make that difficult to install anyway. "Friction fitting" the engine will work fine. I've found that if you kick the engine, MOST of the time the chute will still deploy, but the model will be lighter and therefore drift a lot farther.
The other thing you will find is a lot of people prefer the old style estes clip as opposed to the new style. The old style looks the same on both end, the new one has extra metal at the back end to make it (theoretically) easier to use. You can clip the new ones to look like the old ones.

 

[TwoWalks]

jetra2, powderburner and raw9jr

Thanks, lots of good info and quick replies also. I was beginning to think I had a missing part for the BB2. This makes sence so again Thanks!

 

[BlueNinja]

I think you should use the clip. It is a lot less risky than friction fitting. FF is a little more fun to use at times though. I used it on the Mongoose before I lost it.

 

[TwoWalks]

Originally posted by Blue_Ninja_150
I think you should use the clip. It is a lot less risky than friction fitting. FF is a little more fun to use at times though. I used it on the Mongoose before I lost it.

As I work on both of these kits, one thing keeps popping into my head - All this attention to detail, its probably just going to disappear the first time you fire it! even had a dream last night, was watching the rocket slowly floating down as it drifted out to the freeway and wham along came a semi-truck.

 

[rbeckey]

Don't hestitate to use the C11 motors in the BB2. You're much more likely to get it back.

 

[astronboy]

I fly rockets with both the engine hook, and the 'friction fit' method of motor retention. I like the hook because it is easy to remove motors after launch. The friction fit is best for Scale models and high performece birds.

One trick I use to remove motors from a friction fit rocket is to buy some 3' long 1/2" dowel at Walmart (under a dollar). I then remove the nosecone and fish the dowel into the body tube, past the engine block and into the spent motor casing. I then invert the whole assempby, holding the rocket body tube, and gently tap the whole thing, exposed dowel end first, on the basement floor. I can usually just tap out the spent casing without stressing the body tube or ripping off fins. (My brother is known for shredding minimum diameter rockets with friction fits as he tries to just yank them out with a pliers.)

 

[astrowolf67]

A tip for attaching your fins. I use CA (super glue) to attach the fins to the rocket. I put a drop at each end of the fin root, with normal glue in between. Position the fin, hold it there a few seconds, till the CA grabs, then go to the next one. No need for a jig, or to have to hold it for half an hour waiting on the normal glue to grab.

The Fat Boy is a great first kit. Build it, fly it, love it. After a few launches, go buy another, and put a 24mm motor mount in it. Or, build one for clusters. The Fat Boy is a very versatile little rocket. I'm currently considering a 29mm Fat Boy my self.

 

[TwoWalks]

rbeckey Thanks, I wrote that on the BB card so I would remember. Good idea.

astronboy thanks for the idea of using the dowel to get the motor casings, that sounds like just the trick I would be looking for.

astrowolf67 I was just wondering today if that would work, thanks I will give it a shot. One of the first threads I seen here at TRF was about the 29mm in a fat boy and the idea of a cluster sounds like a fun project also. I have a feeling I see a number of Fat Boy's in my future already.

 

[NewEntity1]

Welcome TwoWalks, or should I say mutual welcome, since you just welcomed me as well

Let me know how those first kits work out for you. I'm going to be real busy next week, so I probably won't start on my first projects until the 13th, but I'll be sure to let ya know how it goes.

I'll have to see if I can get my digital camera repaired as well, so I can 'record my progress', heh.

 

[stevem]

I picked up trick for friction fitting motors with masking tape somewhere on this forum - can't seem to find it now.
Anyway, I wrap the engine with a spiral of masking tape leaving a little space between wraps. This way you can 'screw' the motor in and 'unscrew' it to get it back out. I have found this works very well and have not had any stuck motors nor have any ejected out of my rockets.

 

[TwoWalks]

Originally posted by stevem
I picked up trick for friction fitting motors with masking tape somewhere on this forum - can't seem to find it now.
Anyway, I wrap the engine with a spiral of masking tape leaving a little space between wraps. This way you can 'screw' the motor in and 'unscrew' it to get it back out. I have found this works very well and have not had any stuck motors nor have any ejected out of my rockets.

SteveM Thanks for the tip:
Now that sounds like a great idea - I think I am going to need a good notebook to keep a lot of these ideas in

NewEntity1 - you will have a great time when you get the time to work on the new project. Will keep you and all posted on progress. Infact I will now record my first "oops"

Fat Boy is looking good - I felt really great about the fillets and the over all progress. Then last night I sat fat boy down on a guide for 3 fin alignment and realized that one fin is not on straight - it leans off at a slight angle. I thought about taking it off to get it standing up straight, then reality struck. It is not only glued to the body with fillets but also to the motor tube. The probable odds are that I will break the fin off at the least and or mess up the body and motor tube. I have decided to just ignore it, finish the Fat Boy as a learning experiment and get the parts to build another one.

Who knows, I might decide to launch this one with a lower power motor just to see what it does with the crooked fin. Now what did I learn? I need a jig for alignment of fins, my eye balls are not very accurate.

 

[astronboy]

A crooked fin should not be much of a problem. You may get some spiraling during ascent, but it should not make the rocket unstable. Chalk it up as a learning experience!!

Fred

 

[TwoWalks]

Originally posted by astronboy
A crooked fin should not be much of a problem. You may get some spiraling during ascent, but it should not make the rocket unstable. Chalk it up as a learning experience!!

Fred

Thanks Fred - will do. Should have seen me last night when I noticed it ... must have been a real sight. Now this morning, I just looked at it, smiled and said "Oh Well, guess I have to build another one. "

 

[Fore Check]

Originally posted by astronboy
I fly rockets with both the engine hook, and the 'friction fit' method of motor retention. I like the hook because it is easy to remove motors after launch. The friction fit is best for Scale models and high performece birds.

One trick I use to remove motors from a friction fit rocket is to buy some 3' long 1/2" dowel at Walmart (under a dollar). I then remove the nosecone and fish the dowel into the body tube, past the engine block and into the spent motor casing. I then invert the whole assempby, holding the rocket body tube, and gently tap the whole thing, exposed dowel end first, on the basement floor. I can usually just tap out the spent casing without stressing the body tube or ripping off fins. (My brother is known for shredding minimum diameter rockets with friction fits as he tries to just yank them out with a pliers.)

Another (and perhaps easier) method similar to your dowel method is to invert the rocket and use your launch rod. Works very well for me.

 

[mikeyd]

Originally posted by TwoWalks
Thanks Fred - will do. Should have seen me last night when I noticed it ... must have been a real sight. Now this morning, I just looked at it, smiled and said "Oh Well, guess I have to build another one. "

I have noticed that at least for me, I am the biggest critic of my rockets, building and finishing. Just resently finished my Big Bomarc, My Wife says it looks great, and I proceed to pont out all the areas I am not happy with! I have been in this hobby for a number of years, and just within the last 5 or so got into High power. I still enjoy the small ones, and even have some my son, and I built out of paper towel tubes. These do not have the cleanest lines, or straightest fins, but still fly well. The tall red white and blue one inthe middle of the picture with the USA is his. The rest of the fleet can be found here!https://members.cox.net/shortckt4/main.htm
Glad to have you with us and enjoy!

 

[TwoWalks]

mikeyd That is a fantastic selection of beautiful rockets - but I have to tell you - The red/white/blue USA rocket of your sons is exceptional. The instant the picture was loaded I was drawn right too it. Thanks for sharing that with me.

 

[powderburner]

Originally posted by Fore Check
Another (and perhaps easier) method similar to your dowel method is to invert the rocket and use your launch rod. Works very well for me.

Yes it does work, and in a pinch (if you have nothing else handy) it is certainly better than nothing. I just hate to abuse the launch rod by pushing on it---they can bend, and once bent they are hard to 'unbend' back to straight and SMOOTH.

Astronboy has a good system (using a wooden dowel to tap out the stuck case) but if you try this with a launch rod, you will end up with burrs on the end of the rod. Then you have to find a file to smooth off the burrs, etc.

I usually carry a length of dowel with my field kit, and this is just one of the uses where it comes in handy. You can push out stuck motors. You can tape it to the side of your launcher to create a mast for supporting ignition leads. You can push flame-proof wadding into position deep inside a small tube. You can beat your dog with it. It just comes in real handy.