Mega Mosquito and lazer cut fins

So, I'm assembling my Mega Mosquito, and after piecing together the teeny-tiny mosquito and painting it, I'm tackling the big brother and discovering that it's another kettle of fish.

First, the length of the engine tube is too long by a quarter of an inch. Is the distance between the engine mount rings critical for mating on either end of the slotted fins? I'm beginning to think so, though it's not stated in the multi-lingual directions...

I have started punching out the lazer cut fins, and it's easy...so easy, I'm beginning to wonder about the instructions. The nine sheets of balsa wood fins are smooth and not rough...but the instructions show to block sand them...on the surfaces, both sides. So I do this, producing a little dust, but making no significant change in the smooth sheet of wood.

Now, I could understand sanding of the little stubs of connective points left over by the lazer cuts. But there is no instruction to do this. Nor feather them.

As I prepare to glue the fin sandwich together, I'm supposed to place them under weight while they dry or soak in. How to keep the layers in the right position? What is to keep them from sliding apart, producing a "messy sandwich" of uneven layers? Now the inner hollow layer is not quite the same size as the outer fin. There's about an 1/8" difference, which you can position either at the fin tip, or shove it down by the fin's slot end. I would assume, since the slot is inside the tube and somewhat in between the engine mounts, that's the end that is least important to be lined up. Now, the fins must be tightly mounted and glued to the body of the tube, but is it essential that all layers of the fin line up?

I have not built thi kit, so take what I am saying with a grain of salt. I'm thinking the root edge of the fin, near where the fin tab goes into the tube slot is tho MOST important edge, not the LEAST important. If the outer layers of the fin overlap the tab too much, the tab will not reach the motor mount, defeating the propose of TTW fins. If the outer layers do not quite reach the root edge, there will be a big gap to fill.

I'd suggest putting in the MMT then dry fitting the fin cores and fin skins to see how it all goes together. Only glue on the skins after you know where they need to be. Also, do not use too much glue. If you only smear on a thin layer, it will grab well, and you will not need to worry about things slipping around and ruining your model when you put on the weight.

I am thinking that you may have one of the early kits. could you check the face card (near the barcode) and report the date? all 9 layers are supposed to be the same size, please note which layers are out of spec(photos if you would please). if it is a new kit (date wise) then you should report this to Estes. in the mean time, the root edge/tab edge are the important edges, the other edges get sanded anyway(iirc rounded) so it is easy to take care of the unevenness of the layers(yes the fins on mine were had odd lengths too, this is how I solved the problem ). put a thin layer of glue on both sides of the fin core and then put the 'skins' on this will minimize warping, weight them as per the instructions and allow them time to dry. any residual warping can be ironed out (literally, a clothes iron on linen can de-warp most fins ). apply paper skins if you like, sand the edges, then and only then adjust the fin slots to fit the fins(index the slots to the fins) and attach the fins.
Rex

You should line up the root edge of the fins which will leave the outside edges uneven. After the glue dries use a sanding block, palm sander (which I used), sand paper, etc. to even up the edges of the fins and remove the burn from the fins.

If you use too much glue before weighing down the fins you'll have the problem of sliding that you suggested. Use a lot less glue and you'll be okay. Be sure to smooth a thin layer of glue all over the entire surface with your finger before sandwiching the fin layers together and you'll be okay. I weighed mine down with cookbooks overnight.

In my build thread I papered the fins, but I think on this model that's not necessary. Use some watered down Carpenters Wood Fill and paint that over the fins, let it dry, and sand it smooth. You'll end up with extremely smooth fins that way.

Read how I built mine here:
https://www.rocketryforum.com/showthread.php?48421-Estes-Mega-Mosquito-Build-Thread

Mushtang said:

You should line up the root edge of the fins which will leave the outside edges uneven. After the glue dries use a sanding block, palm sander (which I used), sand paper, etc. to even up the edges of the fins and remove the burn from the fins.
If you use too much glue before weighing down the fins you'll have the problem of sliding that you suggested. Use a lot less glue and you'll be okay. Be sure to smooth a thin layer of glue all over the entire surface with your finger before sandwiching the fin layers together and you'll be okay. I weighed mine down with cookbooks overnight.

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Mushtang is right on this.
Use less glue and the outside balsa sides will be less likely to slip when the weight is set on them.
I'm also building the Mega Mosquito right now.
Instead of gluing both sides at once (glue on both sides at the same time might lead to more slipping) glue it one side at a time for more control.
Under the weight of some heavy books you shouldn't get any warping.

More vague instructions!
The instructions don't mention the importance of aligning all three of the root edges.
I actually (very slightly) stepped the outside fin veneers to better fit the curve of the body tube.
Looking at it now it's probably not needed but the fins end up 1/4" thick and I was trying for better fit on the body tube curve.
When all is glued up you will want to sand all outside fin edges flush.
After it dries there is no way to sand the root edge so root edge alignment is critical.

The instructions make no mention of rounding the edges of the fins.
I rounded the leading an trailing edges, they would look a little clunky all squared off.
The original Mini Mosquito instructions say to air foil the fins! Like the little Mosquito needed to go any faster or higher!

I'll probably do epoxy fillets. They aren't really needed for E and F engines but this is an upscale.
Smaller rockets get (smaller radius) Titebond M&TG fillets.
A model this big gets upscale (larger radius) epoxy fillets.

So I went and re-read Mustangs build thread.
The finished product looks great! Very clean work.

I found the picture of the outside fin edges pretty interesting.

View attachment 169689

All three fins had the center core piece slightly recessed when looking from the outside rounded edge.
When I glued mine up I purposely stepped the core (middle) piece to fit the curve of the body tube.

I wonder if Estes purposely cut if the interior piece a little shorter?
If the builder glues all three of the outside rounded edges flush (instead on concentrating so much on the root edge)
would the three root edges end up "stepped" to automatically fit the body tube curve?

If so, this should have been addressed in the instructions.

It would appear that in their effort to be multi-lingual, Estes has sacrificed detail in instructions and advise on how to finish the fins and edges.

I wish I had read all your suggestions before I proceeded last night.

The thing that bothers me is the lack of details, telling you to adjust the two motor mount circles to the exact length of the fin tab. But I already glued them. And after inserting and checking the dry fit, I glued the fins in place, but find the tabs must impact the motor mount, cause the root edge of the fins don't stay tight against the body tube. The fins were allaigned to keep the outer edges together, thinking that they might be feathered later, but there's no instruction for that.

I just feel like I've gone too far down the path to make corrections now, and more detail in what to check and what was critical might have helped. I couldn't put the Mega Mosquito on the fin jig, so I laid it down on the upturned egg carton to hold it, as I turned the fin being glued upright...vertical, on top. But still, as it dried, the fin appears to not be held firmly against the body tube, and gaps appear along the body tube.

It occurs to me that if the root edge of the tab was to be glued against the motor tube in the motor mount, there would be no way to apply that glue. Any that has been smeared along the sides of the tab has been scraped off the side of the blade as it was inserted.

I just think the whole assembly of the fins could have been explained in more detail, IF it is that critical.

hcmbanjo said:

So I went and re-read Mustangs build thread.
The finished product looks great! Very clean work.

Click to expand...

Thanks! Coming from the Master that really means something.

hcmbanjo said:

I wonder if Estes purposely cut if the interior piece a little shorter?
If the builder glues all three of the outside rounded edges flush (instead on concentrating so much on the root edge)
would the three root edges end up "stepped" to automatically fit the body tube curve?

If so, this should have been addressed in the instructions.

Click to expand...

I'm guessing not. The picture you show is after I'd already sanded a lot of the outer layers some. They started much longer.

My guess is that if the ends of the fins had been lined up like you say the resulting "curve" at the tab would be a smaller diameter than the large body tube. And it would be VERY difficult to sand the root edge to a rounded curve (instead of stepped) for gluing. I think if they had intended for this to be done they would have suggested putting the tab in the slot, clamping the outside layers so they're flush with the tube, marking their locations, and then gluing together Even that doesn't sound like it would work well.

Also, the tab appeared to be very carefully cut to the exact distance to reach the motor tube. If a "curve" was created at the root edge by gluing the outside layers closer you'd risk shortening the tab and keeping it from touching the motor tube at all.

But... it sounds like you've done this already and I'm just guessing, so you'd know better if this is an issue. I'm looking forward to your MM build on your blog!!!

Sounds like one of those instances where I would have discarded the instructions and just used "Common Sense Building Techniques", dry fitting all of the Parts and modifying them as needed.

Kirk G said:

It occurs to me that if the root edge of the tab was to be glued against the motor tube in the motor mount, there would be no way to apply that glue. Any that has been smeared along the sides of the tab has been scraped off the side of the blade as it was inserted.

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If you leave the rear centering ring off you'll have access to glue all edges of the fin tabs inside the body. I've shown this in my build thread linked above.

I think if you don't do it that way, and apply glue only to the root edge of the fin, you'll still get a well glued fin. The glue fillets on the body will become more important for strength too. If you glue the tabs inside the body tube without the rear centering ring you'll have a lot stronger bond and fillets will just be for looks.

You will, of course, glue the rear centering ring in place eventually, after the glue inside the body dries.

Maybe you'll get "lucky" like I did and lose your first MM to a tree, and end up building a second one!

Kirk G said:

It would appear that in their effort to be multi-lingual, Estes has sacrificed detail in instructions and advise on how to finish the fins and edges.

I wish I had read all your suggestions before I proceeded last night.

The thing that bothers me is the lack of details, telling you to adjust the two motor mount circles to the exact length of the fin tab. But I already glued them. And after inserting and checking the dry fit, I glued the fins in place, but find the tabs must impact the motor mount, cause the root edge of the fins don't stay tight against the body tube. The fins were allaigned to keep the outer edges together, thinking that they might be feathered later, but there's no instruction for that.

I just feel like I've gone too far down the path to make corrections now, and more detail in what to check and what was critical might have helped. I couldn't put the Mega Mosquito on the fin jig, so I laid it down on the upturned egg carton to hold it, as I turned the fin being glued upright...vertical, on top. But still, as it dried, the fin appears to not be held firmly against the body tube, and gaps appear along the body tube.

It occurs to me that if the root edge of the tab was to be glued against the motor tube in the motor mount, there would be no way to apply that glue. Any that has been smeared along the sides of the tab has been scraped off the side of the blade as it was inserted.

I just think the whole assembly of the fins could have been explained in more detail, IF it is that critical.

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I agree, the "internationalized" instructions on most Estes kits are not good, and it's only experience that saves you half the time.

Typically, there are two ways to glue through-the-wall fin tabs to the motor tube. The advanced technique that is often used for mid power and high power rockets is to leave off the aft centering ring, and that way you have access to the inside of the fin can, and you can add internal glue fillets between the fin tabs and the motor mount. Then you glue on the aft centering ring later after the internal fillets dry. I'm sure that is not what is described in the instructions, and is probably not necessary for a low power rocket like the Mega Mosquito.

The typical way is to glue in the motor mount first with all the centering rings already glued into place. Then dry fit everything by poking the fin tabs through the slots until they contact the motor tube. If the tabs touch the motor tube, but you still have a big gap between the root edge of the fin and the body tube, pull out the fin and lightly sand the tab down until it fits better. Do this with all the fins so that when the tab touches the motor tube, the root edge just barely touches the body tube. Dry fitting also allows you to check that the fin tab will fit in between the centering rings --- you can sand the width of the tab to make it fit if necessary.

Once everything has been dry fitted and sanded to fit, apply a bead of glue along the entire root edge of the fin and edges of the tab everywhere it will contact the cardboard --- along the root edge of the tab where it will contact the motor tube, along the top and bottom edges of the tabs where they will contact the centering rings, along the root edge of the fin where it will contact the body tube. You can also add glue along the flat sides of the tab where it will contact the edges of the slot, but you can also just fillet that area later. If you are using wood glue or white glue, you might want to let it dry just a few minutes before putting in the fin to let it get sticky and tacky. Then poke the tab through the slot until the glued edges touch the motor tube, centering rings, and body tube. Position it like you want it, and let it dry, then glue the next fin. Once all the fins are dried, go back and make glue fillets along the entire edge where the fin meets the body tube. Now you will have a nice tough fin can with the fins glued firmly at all surfaces.

So that's for future reference. What are you going to do to fix the kit you have?

If the fins are loose and wobbly, I would probably suggest trying to remove them and use the procedure above. If they are stuck in place and you do not want to attempt trying to carefully cut them out, you could drill small holes in the aft centering ring between the fins and dribble glue into the fin can in a way that it will flow against the edges that should be glued internally. Or if you really want that fin can to be super solid, some people fill it with expanding foam! If there are gaps between where the fins should meet the body tube, you can probably fill it with glue fillets. Use something thick that will fill the gap like the Titebond Molding and Trim glue. There are other gap-filling glues you could use too. Or a thickened epoxy (you'll have to ask someone else about how to do that).

Good luck, and don't give up! Next time you do TTW fins, you'll be an expert!

Thank you for all the tips.

Having never done a TTW or slotted fins before, I'm discovering that there's a buch that Estes apparantly no longer tells you to check.

I may have to drill that hole or three through the rear centering ring, and dribble some CA or wood glue inside. Right now, I fear there's too large a gap between the fin and the body tube, and NO glue on the root end of the tab to attach to the motor tube at all. (It didn't show to do that...only to coat the side or flats of that tab...which was squeegeed off when it was inserted in the tab. I know I've impacted the motor mount, cause the fin "fights back" against being shoved any lower.

I really don't want to have to buy another Mega Mosquito again...but I'm thinking that I might have to do so, after I loose/wreck, destroy this first one...especially if Estes has another great sale.... someday. I only got this cause it was the first D size engine rocket that I own and somebody in the club said they'd give me a sample to fly it. (If the vendor shows up, I know he carries ALL motors in v arious clear bins to sell at the launch. But I can't count on that, I guess.)

I'm am curiously tempted to try the kit again, having learned what NOT to do....but we'll see if i can salvage this one, and get it too fly, if the fins are not too wobbly.

I was hoping to prime it tomorrow, but I'll have to see about waiting and trying to shore up those fins...fillets and holds.

Any thoughts on why they have us still sand balsa fins that are smooth to the touch already?

Which do you recommend for this internal surgury? Elmers Carpenter Glue, Tightbond no0-drip, or think CA?

Im confused. What are instructions? where do you mount them to the bt?

I'd probably go with the Elmer's carpenters glue for the internal surgery, because I think it will flow to where you want it. And then use the Titebond no drip for the external fillets. After that, if it seems solid, and there are still gaps, you can fill them with Elmers wood filler. Give it a shot. I bet it's salvageable.

Another thing you might want to do is to give Estes Customer Service a call and let them know you think the kit might not be built correctly due to poor instructions. No guarantees on what they will do, but their customer service is pretty good, and they might find a way to help you out. Who knows? They might send you a replacement. They are a good company and very good about warantee claims and other customer service issues. It's worth a shot, and the company should know if the instructions are lacking. I'd definitely call them about it.

The Mega Mosquito is a cool flyer with nice slow stable flights. You are going to enjoy flying D motors and even better on E's! I got one at the Amazing Estes Sale, but I have so many kits in my queue that I let my buddy have it. I'm looking forward to seeing him build and fly it, and I'm going to let him know about some of these "gotchas" that you've brought up in this thread.

DizWolf said:

Im confused. What are instructions? where do you mount them to the bt?

Click to expand...

If you had read the instructions you would KNOW where to mount them!

But seriously, if you are new to this, instructions are very helpful, and the new internationalized Estes instructions are not good. If you've never done TTW fins, it's not obvious what you need to do. After you do a few, you can probably do it in your sleep, but until then, some tips are good to have.

Agreed. The new instructions are terrible. I've heard all about why they did it and had to be trilingual. The implementation is poorly done. I know what I'm doing and they confuse me. Three separate sets would be the way to go. It's worth the extra paper to do it right. It's important. Not the place to save pennies.

DizWolf said:

Agreed. The new instructions are terrible. I've heard all about why they did it and had to be trilingual. The implementation is poorly done. I know what I'm doing and they confuse me. Three separate sets would be the way to go. It's worth the extra paper to do it right. It's important. Not the place to save pennies.

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It does seem ridiculous to skimp on instructions, and three complete sets would be way to go. A one-time translation is not that expensive, and printing three sets would be pennies per kit. (Speaking as a former tech writer, instructions are IMPORTANT!)

Kirk G said:

NO glue on the root end of the tab to attach to the motor tube at all. (It didn't show to do that...only to coat the side or flats of that tab...which was squeegeed off when it was inserted in the tab. I know I've impacted the motor mount, cause the fin "fights back" against being shoved any lower.

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My suggestion is to try and pull the fins out. If there is as little glue on as you indicate, you'll probably be able to take a sharp knife and cut the glue around the tab/slot loose and pull them free. Then sand all the glue off and start again.

It definitely sounds like you need to sand the tabs a little shorter. Go slow when sanding, it's easier to take a little more off than to put a little more on. Also number the slots and tabs so you can keep them in the same configuration once you get them sanded to fit. The root edge of the fins should be very snug against the body tube allowing you to glue there, as well as the root edge of the tab should be glued to the motor tube inside. Let a little glue run into the slots onto the centering rings before sliding the fins in and you'll get a good bond there as well.

Good luck, and keep us posted.

Show us some pictures of how it looks now, and document the fix. We'd love to follow along.

Oh Mushtang,

You make me so ashamed... I've been proceeding along, posting questions and not waiting for answers, and getting myself in deeper and deeper. I guess I've resolved that I may be making another one of these and so not wanting/waiting to be perfect.

I hadn't thought of posting a build thread...with photos.... that just sounds a little egotistical for me (me of the large ego, HA!) but I can see where a photo would be worth a thousand words.

Just tonight, before logging on, I made a slurry of Elmer's Wood Glue and "painted" or sealed the large fins for the first time.
I SHOULD have done this before inserting and mounting them... but I was in a hurry and didn't think it through last weekend.
Ditto, I failed to feather the edges too....

But spotting someone's photo of an orbital sander, has encouraged me to unpack my wife's unit, and go after those leading edges with the orbital sander. Unfortunately, I have only one grit of "paper" to work with for the sander, and might have to make a trip to Lowes to see if the sell a variety pack for vecro-attached sanders. But I am encouraged, that with the proper gluing, I can yet feather the edges and with some hand sanding (or maybe orbital...it's a large enough fin!) I could get a smooth enough surface that would allow me to prime later in the day or before the weekend... (I HATE my can of Valspar white primer spray paint...it NEVER seems to cure/dry fast enough for me)

And I'd like to shoot the rocket with Gloss Yellow spray paint on saturday, and maybe some black and/or red accents on Sunday.

Then, I've got to hold the thing while tying in the chute and pre-packing with (what? Dog Barf, or Estes recovery wadding...what do you recommend?) prior to taking it to the launch on the second Saturday of the next month.

Maybe I'll shoot some snaps tomorrow if I can find my wife's digital camera and post a few close-ups. I think this one is salvagable... or else, I'll foul it up and then go more carefully the next time around. Which I had had some slotted fin experience under my belt before I started this one....

I took one look at the short body tube and said, 'chute hankie'. course I also figured that a nylon chute was better than the stock chute . Apogee says a 9" x 9" Nomex blanket is a suitable size for the mega mo.
Rex

Tried to snap a few shots of the Mega Mosquito in progress. Don't know if the wife's Digital camera that she left out overnight in the freezing temps will work. I Note the 1/8" gap at the base of the third fin. I've tried to fill it with Elmer's Carpenter Glue.

Looks like your paint has a little smudge on it.

Kirk G said:

Tried to snap a few shots of the Mega Mosquito in progress.View attachment 169981View attachment 169981View attachment 169982
Don't know if the wife's Digital camera that she left out overnight in the freezing temps will work. Try this.View attachment 169981
Note the 1/8" gap at the base of the third fin. I've tried to fill it with Elmer's Carpenter Glue.
View attachment 169983

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Now, I'm not sure if it is just me, but the photos look like psychedelic purple abstract art of some kind. I do not see a rocket.

Is this one of those 3D posters you have to stare through?

There was a Thread recently about why Valspar Spray Paint sucks big time and to never ever use it or let it get near your Rockets.

That said, I think your Wifes Camera has failed you. I too see the Magical Mystery Purple Pics'.

Purple Haze in my camera's brain,
lately pics just don't look the same,
postin' photos but I don't know why
'scuse me while I squint my eye.

ThirstyBarbarian said:

Purple Haze in my camera's brain,
lately pics just don't look the same,
postin' photos but I don't know why
'scuse me while I squint my eye.

Click to expand...

:rofl::rofl::rofl::rofl:

Sorry guys, but she left the $200 camera in the jump seat pocket of our Vibe overnight...and it hit freezing here. Scratch one camera. I was hoping it would only be the view screen, but it appears the thing is scrap now.

I was hoping you could make out the big bald fins, but I guess not.

I'll try to find another camera soon. I have to go beat her now...

I have one that I plan to build by aligning the tips and then beveling the roots of the "outer" panels so that they conform to the airframe. Then after a test fit, I'll glue the three sheets together.

I recently completed this kit. I built my fins up using Elmers and about 10 clothespins, then sanded the edges.

Looking forward to seeing how she flys at the Great lakes launch.