Quick and Easy Fin Fillets with Hot Glue

[sr205347d]

This complements my quick and easy fin and body tube covering with packing tape technique.

Colored Packing Tape to Cover Body Tubes and Fins

In doing some rapid prototyping (trial and error, mostly error), I wanted a quick and easy way to build and modify a model. You can get colored packing tape on Amazon in a rainbow assortment plus black and white, or just one color. For the body tubes, apply the tape parallel to the tube. For...

www.rocketryforum.com

 

[hobie1dog]

 

[Steve Shannon]

That looks good. The hot glue I've used has too much flexibility, but it's probably something different.

 

[dr wogz]

The fins are glued onto the body tube. but the body tube is pre-coloured with packing tape? do I read that right?
And the hot glue is then added onto the packing tape (on the body tube & on the fins)

How hot is the hot glue when applied / smoothed? And does that affect the tape in any way?

"plastics" can be notoriously hard to glue to.. (especially glossy / smooth plastic surfaces)

Same concerns Neil has in your original thread.. Nice work, but I am not a fan of tape & hot glue as structural adhesives..

 

[samb]

No experience all with hot glue. How is the surface after it cools/dries/cures? Soft or hard? Can you score with a fingernail? Does it take paint? Any report on durability over time or number of flights?

Gluing painted surfaces seems counterintuitive. Are these meant to be cosmetic additions to a structural fillet, to build up a radius?

 

[sr205347d]

The fins are glued onto the body tube. but the body tube is pre-coloured with packing tape? do I read that right?
And the hot glue is then added onto the packing tape (on the body tube & on the fins)

How hot is the hot glue when applied / smoothed? And does that affect the tape in any way?

I cover the fins with tape except for the roots. Then I glue them to the body tube. Then I tape the tube.

I have a variable temperature glue gun with the temp set just below the boiling point of the glue. I have Gorilla brand hot glue. Apply the glue to the joint, and without delay, smooth with the popsicle stick in one stroke, and remove the masking tape. Hot glue is about the only thing that will stick to the tape.

Sure, it is not as strong as epoxy, but I am not going supersonic.

 

[sr205347d]

Does it take paint?

Paint? I don't know what that is.

 

[samb]

This stuff ?



Gorilla says it will take paint. Interesting stuff, thanks for sharing. Love to hear about durability down the road, or after X number of flights.



https://www.gorillatough.com/product/gorilla-hot-glue-sticks/

 

[sr205347d]

This stuff ?

Yup.

 

[rocket_troy]

That looks good. The hot glue I've used has too much flexibility, but it's probably something different.

Yeah, that would also be my concern. There are various flavours of hot melt glue, but being a low melt (and even lower GTT) thermoplastic (and a soft one at that) I'd be particularly concerned on really hot days.

TP

 

[reddrock]

It's not the speed of the flight that is likely to get you, but the motors heating up and loosening the glue. Long burn motors are worse.

 

[waltr]

And the Summer sun heating the glue.

 

[neil_w]

I am very skeptical of using hot glue for rocket construction, at all. It might work sometimes, under the right conditions, but I would never trust it.

However, credit where credit is due: there has probably never been a nicer-looking set of hot glue fillets on a rocket, ever. Kudos to the OP for an unbelievably clean job.

 

[sr205347d]

And the Summer sun heating the glue.

I don’t think you need to worry about ambient temperature. Here is a YouTube channel of a guy in Arizona who builds RC airplanes and drones using foam board, packing tape, and hot glue.

https://youtube.com/@ExperimentalAirlines

 

[sr205347d]

It's not the speed of the flight that is likely to get you, but the motors heating up and loosening the glue. Long burn motors are worse.

I would think that the airflow would keep temps down in flight.

 

[waltr]

I would think that the airflow would keep temps down in flight.

While on the pad waiting to launch?

 

[Steve Shannon]

I would think that the airflow would keep temps down in flight.

It does, except at discontinuities where there could be stagnation and heat build up, but you already said you're flying it below Mach, so I agree that heating shouldn't be an issue. Also, you have two layers of paper, which isn't a terrible insulator, between the fillets and the outside of your motors. Heat transfer takes time and rocket motors burn fast (relatively) so your fillets should never be exposed to too much heat from a motor.
As far as sitting in the sun, there can be hot areas where two surfaces meet at an angle and the sun is concentrated. I've seen lots of vinyl siding blistered in inside corners as a result. You might want to test that by setting your rocket in the sun on a hot day.
Flexibility was my primary concern. Fly it and find out.

 

[Sandy H.]

I like the creativity. It is absolutely not a 'one size fits all' solution, but it is creative and I bet will work under a lot of fun flying situations. I think questioning the typical methods and approaching alternative ideas responsibility (i.e. not hey y'all watch this!) is a great way to become an expert and @sr205347d is doing that, IMO. Love it! Succeed, fail, learn, share. Nice!

Sandy.

 

[sr205347d]

Flexibility was my primary concern. Fly it and find out.

I haven't flown that one yet, but check my thread on bellyflop recovery. Except for the Dragonite, they all use hot glue. It isn't rubbery.

Bellyflop Recovery

I recently re-entered the hobby, so it is quite possible that someone has already done this and I am unaware. That said, inspired by the SpaceX Starship, I thought that a model rocket descending in a bellyflop attitude could land with no damage, provided that there are no fins on the belly side...

www.rocketryforum.com

 

[sr205347d]

I like the creativity. It is absolutely not a 'one size fits all' solution, but it is creative and I bet will work under a lot of fun flying situations. I think questioning the typical methods and approaching alternative ideas responsibility (i.e. not hey y'all watch this!) is a great way to become an expert and @sr205347d is doing that, IMO. Love it! Succeed, fail, learn, share. Nice!

Sandy.

Thanks!

 

[Ladykate]

I use hot glue on my RC RGs. I don't use it on the motors or motor cans - it wouldn't work for that. As far as ambient temps, leave any rocket in a hot car and you risk warping. With hot glue you would get to reassemble something. So... don't do that. Outside - like waiting on a launch, it certainly is not a problem. I also use it on foam board airplanes and simply have never had an issue. Many years worth of examples.

Having said all that, my hot glue fillets aren't all that good - I usually use the FliteTest method of scraping the glue joint with a small piece of foam board. I would use the normal methods for good looking fillets.

 

[Back_at_it]

I can see that as long and the bond is cosmetic and not structural. Hot glue isn't strong enough to bond fins but I can see it used as external fillets of the fins are TTW with internal fillets.