Nose Cones Sticking... Could it be the Humidity?

[frogglicker]

Saturday, I had nose cones fail to deploy on two rockets, and one chute got stuck in the tube (which might be unrelated). Those two rockets were lost. While Colorado is pretty dry, we've had a lot of rain lately and Ft Lupton felt more like a Central Florida summer than Colorado. Can the humidity cause stiction on the nose cone shoulder where it normally wouldn't in drier conditions? I have never had this issue before when my nose cone had a "Goldilocks" friction fit.

My method of testing the nose cone fit is by holding the rocket by the nose cone. If it doesn't slip, I will give it a little shake. If it starts to separate with some resistance, I call it good. I have been using this method for decades and this weekend was the first time I had a lawn dart, let alone two on the same day.

Also, my Big Red Max had a drag separation at ~800ft where the apogee is typically 1100+. Nothing was changed on this rocket and this was its 6th flight, 4th on G motors. Could the temperature in combination with the humidity be the cause? I am somewhat vexed. This was the first launch with ambient temps over 70 degrees and humidity over 25%. I will add that I prepped these rockets at home vs. the field, so the environmental change may have played a part.

Thank you for any insights or input.

EDIT: Does anyone have a way to combat this, like talcum powder or magic fairy rocket dust?

 

[Bill S]

I've seen nosecones get tighter if the rocket has been left out in the sun. I try to keep them in the shade or covered, especially darker colored ones.

 

[SolarYellow]

I fly the same cardboard rockets in the swampy South and in the CA desert. I remove all masking tape from the NC shoulder after flying and set NC friction fresh at the launch site just before flying. There's a big difference in fit that correlates to the humidity. Temperatures are similar both places.

 

[Tractionengines]

If they have black nosecones the time in the sun will expand them some. (This is something I watch on the 3" Big Red Max.) Also, and tape can get "stickier" if it sits in the hot sun.

 

[Adam3836]

Agree with the above mentioned if its hot and the rockets sitting in the sun I have seen the nose cones become a tight fit
Keep ‘em under shade and use some baby powder on the nose cone shoulder to help

 

[frogglicker]

This has been very helpful. I am now moving my "Nose Cone Fitment" checklist step from prep to pre-launch and more baby powder on everything . After the whoopin' I received from the LCO (j/k... he's a great guy), I'm hyper-focused on this. The next launch will be up in the mountains 3000+ feet higher and I'll have something else to work on.

In the scheme of things, it wasn't a horrible loss. One rocket was an experimental 3D Printed rocket with a Top Flite chute and the other was my son's Goblin. So, it was really just the Chute and the Goblin and what I learned was much more valuable.

 

[teepot]

The guy next to me at last Saturdays launch wasn't able to fly because all his NC's were stuck. Day started out about 70 and went to 95. He didn't have a shelter. His rockets were on a table in the sun. Nevada sun at 3000' on the dry lake. I hadn't heard of nose cones swelling like that before. I don't know what his rockets were made of. Mine are cardboard, plywood and regular plastic nose cones and I haven't experienced this before. Mine were on cradles in the sun. I did my prep under the shelter. Our humidity is low during the day. Goes up at night. Something I'll pay attention too in the future. A thought, would a FG rocket be more prone to swelling rather than a regular cardboard tube?

 

[SolarYellow]

Plastic expands in the heat. Cardboard also shrinks as it dries out.

 

[Handeman]

I understand it's called relative humidity because it's relative to the temperature, but from the OPs post, it's also relative to where you live and what you are used to.

OMG, high humidity when it's over 25%? I would never say it was humid until the humidity percentage went above 65%. Guess it's what you are used to and where you live. It's all relative to more then just air temp.

We've flown in winter temps about 30° to 40° where relative humidity were about 25% to 35% to warm days at 70° to +80° where humidity was 70% to 80%. Those are the days where you can cut the air with a knife! I have not had any nosecone friction fit issues because of humidity between the cold and hot days. At the same time, my rockets live in year round 35% to 45% in my basement because I run a dehumidifier, so getting a little time in higher % at a launch probably doesn't affect them much.

I'm wondering what amount dimensional change the cardboard tubes have for different humidity %. I expect it is a much larger difference when going from a 10% to 40% humidity than it is from a 40% to 70% humidity.

 

[SolarYellow]

We've flown in winter temps about 30° to 40° where relative humidity were about 25% to 35% to warm days at 70° to +80° where humidity was 70% to 80%. Those are the days where you can cut the air with a knife!

Just to note, although it feels the opposite to me as well, humid air is less dense than drier air, not more. Due to its three-atom structure, H2O is a bigger molecule than O2 or tightly-bound N2, but has substantially less mass than either.

 

[frogglicker]

Most of the time, Denver is pretty dry. I have lived in Las Vegas and Central Florida (extremes on the humidity scale), and it was definitely much more humid than I typically encounter here because we have had Florida-like rainstorms almost daily. It was so weird that I had two extremes with the nose cone sticking on two and then the drag sep on the BRM. It wasn't hot, but it was warming up when I launched and all the rockets were in the hatch of the car, with the hatch open.

I will be attempting my L1 cert this weekend, at a new field, 8K ft AGL, so nothing scientific about the next test but I will do the fitment test right before launch. And my Tripoli witness is going to be scrutinizing everything anyway, so I should be good... I mean, what could go wrong?

Thank you, all, for your posts and advice.

 

[Art Upton]

Long story short or decades even on small NAR competition rockets in the 70s.

Don't fit your nose cone tape until your ready to go to the flight line.

Works the same for L1-3 as well

 

[86mustang408w]

I sand the shoulder with 1000 grit or so, then use a little baby powder if necessary on the NC shoulder. And tape if its too loose. Best it to be able to pick your rocket up by the nosecone and it should stay together. if it doesn't, while you gently shake the nosecone with the ricket in the air and it comes out very easy or just falls down, it needs some tape oN THE SGOULDER. I use painters tape like the blue stuff or Frogtape so it doesn't leave real sticky residue..

 

[frogglicker]

Update: I had no issues with the Hobgoblin during my L1 cert flights. It was probably more humidity than heat on the "sticky" day. Plus, a little baby powder helps with chaffing .

 

[86mustang408w]

Sorry about my horribly typed post above. I found another thing to help them from sticking is using a little bit of baby powder on the shoulder right before the flight. My Big Daddy was sticking bad in the heat, that seemed to help right before the flight.

But going recently to my L1 cert flight and even with using dog barf before. Getting that "dust" inside the body tube made the fit extremely loose. Taking a wet wipe and running down the inside of the body tube before inserting the NC helped avoid a drag separation. Something to look out for, sometimes when you dump it in the dust gets all over. Just an observation...

 

[frogglicker]

Thanks for the reply. It's all good. That day, I was prepping for my L1 (actually planning to fly that day), but it didn't quite work out the way I planned. It wasn't a fun day for launching. It was super humid and I was anxious about the flight. I need a coach with me to remind me to breathe! LOL

I now keep the baby powder my my launch bag along with green frogg tape The Frogtape seems to be less "gooey" in the heat. Before I slide the rocket on the rails, I have one more go at the nose cone. If I don't like it, I'll take a minute to try to repair it otherwise I scrub the launch and come back again after it's sorted. I haven't had any more issues with nose cones. It was just a weird day.

 

[Handeman]

I've always waited for the day when things stuck the most, then sanded the tube and/or shoulder until it fit the way I wanted it. For all other days when it's looser then desired, a few strips of masking tape does the trick.

The phenolic piston in my PML Quantum Tube Callisto is tightest when it's cold out. I sanded it to size when it was about 28° F. It's even looser on most days, but it still works fine and I haven't had to adjust or sand it in 10 - 15 years now.

Don't over think it.

 

[RocketSquirrel]

Saturday, I had nose cones fail to deploy on two rockets, and one chute got stuck in the tube (which might be unrelated). Those two rockets were lost. While Colorado is pretty dry, we've had a lot of rain lately and Ft Lupton felt more like a Central Florida summer than Colorado. Can the humidity cause stiction on the nose cone shoulder where it normally wouldn't in drier conditions? I have never had this issue before when my nose cone had a "Goldilocks" friction fit.

My method of testing the nose cone fit is by holding the rocket by the nose cone. If it doesn't slip, I will give it a little shake. If it starts to separate with some resistance, I call it good. I have been using this method for decades and this weekend was the first time I had a lawn dart, let alone two on the same day.

Also, my Big Red Max had a drag separation at ~800ft where the apogee is typically 1100+. Nothing was changed on this rocket and this was its 6th flight, 4th on G motors. Could the temperature in combination with the humidity be the cause? I am somewhat vexed. This was the first launch with ambient temps over 70 degrees and humidity over 25%. I will add that I prepped these rockets at home vs. the field, so the environmental change may have played a part.

Thank you for any insights or input.

EDIT: Does anyone have a way to combat this, like talcum powder or magic fairy rocket dust?

The last time i launched i had an issue with the nose cone, i ended up having to peel a layer from the coupler for it to fit right. It fit fine at home, but once it got acclimated to the outside temp/humidity it locked up.

By peeling off a layer of the coupler, it made it super thin. When i got home i covered the entire thing with thin layer of CA. Wiped it around with my finger. Its firm and fits the same as before.

Bring extra sand paper/masking tape, thats my way around it i guess.