Composit Bush Plane Suited for Arctic Operations?

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paraplane

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I'd like to ask questions/start a discussion on suitability of composit aircraft for Bush operations in arctic conditions. From what I've seen in construction of tent shelters type for useage in arctic conditions aluminum structures are used predominantly/preferred as aluminum I suppose has less fatigue/failure potential as opposed to fiberglass/graphite structures. Now this assumes much specifically comparing questionable quality unidirectional graphite tent poles to that of aluminum.

My thinking is that take a Sailplane flying at high altitude for example Perlan or aircraft such as Proteus or White Knight. These craft spend considerable time aloft where with wind chill factor temperatures must be extreme/rival sea level arctic conditions.

The comparisons of these to tent poles are not exactly on par yet I imagine there is useful evidence that composit structure could indeed tolerate harsh environments. Just food for thought and exploding options.
 

Map

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Composites gain strength when they are cold, metal gets brittle and may break sooner.
Small composite repairs can be done with a heat gun/hair dryer if necessary, larger ones are best taken to a heated shop.
 

BBerson

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Airliners made of composite and aluminum and steel fly at -60 at 35,000 feet, no problem.
The Alaska operators mostly don't fly in colder than -40.
Unreinforced gelcoat can crack in the cold.
 

blane.c

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The biggest problem for me with "slick designs" is ground handling, you have to put some "handles on it" or it is problematic to move it around on the ground especially when your feet are on ice or in deep snow.
 

blane.c

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-40 is the same for C and F it is were they cross. -40 is a temperature many wait to see before venturing out and is not considered a limitation with the people I flew with. I have seen -65 on the thermometer with "brisk" winds many times. Severe cold is nearly always associated with temperature inversion and as soon as getting even 500 ft in altitude the air will be much warmer and continue to get warmer until it normalizes with higher altitudes.
 

Victor Bravo

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Composite is one thing, smooth laminar surfaces are another. Many times they do go together, but I am pretty sure a smooth laminar shaped airplane is not going to work in the "real world" of bush operations, whether composite or metal or anything else. So taking the entire smooth/laminar thing out of the discussion for a moment, and constraining this to composite structure regardless of aerodynamic shape...

I still believe that there is a reason that there are very few composite bush/utility aircraft.

I have zero experience operating an airplane in cold weather, or up in ice and snow, and I know a lot of you guys on HBA have decades' worth of experience doing that. But I do believe that a good valid comparison is this:

Make a list of all the composite aircraft structures that are truly successful in genuinely cold/ice/snow conditions. Then make an accurate assessment of what the maintenance and repair budget, facilities and crews are for those operators.

Now make the same listings and assessments for aluminum sheet metal airplanes and steel/fabric airplanes.

Again, I have no personal expertise on which to base this, but I suspect that you will find that the composite structures are mostly on airliners and military airplanes, and there are bigger crews working in enclosed hangars with significant financial budgets... and that the successful small and medium sized operators who do not have large crews, large budgets, and large hangars are operating sheet metal and fabric airplanes.

This is not to say it can't or won't work. But I believe it is fair to say extreme environments (like severe cold/ice, or 120 degree deserts, or jungle warfare) have the ability to weed out what works and what doesn't work pretty quickly.
 

narfi

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A metal airplane can be repaired in cold weather. It may be difficult to repair field damage to a composite structure in the Arctic.


BJC

stuff breaks in the cold, doesn't matter what it is made from,
stuff breaks in bush conditions, it doesnt matter what it is made from,
so you need to be able to repair it.....

I think the answer depends very much on how extreme you want to be.
 

BJC

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stuff breaks in the cold, doesn't matter what it is made from,
stuff breaks in bush conditions, it doesnt matter what it is made from,
so you need to be able to repair it.....
... in the field. Yup, that was the point of my post.


BJC
 

narfi

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hehe, I was agreeing with you :)

Epoxy doesnt cure very well at negative F temperatures....... not even negative C temperatures which we still consider warm here. (don't even fight my son into wearing a pants and a jacket outside at -C)
 

Pilot-34

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I’m not sure if it’s true or not but there are stories of Corvettes shattering when striking a chunk of ice in the road at 40 below zero.
True or not it might affect the decision to purchase a composite airplane for winter bush work
 

Jerry Lytle

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You won't fly a composite out of the wilderness if it had been chewed by a bear. Rag and tube and duct tape and presto:
1609795487046.png
 

Victor Bravo

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For Immediate Release
Aleutian Islands, AK- January 4, 2021: Greenpeace and World Wildlife Fund jointly files $50M lawsuit on behalf of endangered Kodiak bear, due to injuries sustained by bear after eating carbon fiber bushplane...

"The bush pilot should have known better... he had a responsibility to construct the aircraft out of materials that would nourish the bear, not injure it..." said Susan "Tree" Hugger, Vice Chairwoman of WWF in a statement on Monday; "We are working closely with the bear's attorney Gloria Allred on this important legal precedent."
 

blane.c

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Bears frequently molest anything that has any trace of blood on it. They have sense of smell far beyond our capability and will chew on most anything that has a drop of scent on it. Many have lost vehicles, property and been injured or killed for lack of appreciation of this fact. Care to put everything into the plane so it won't leak fluids will make your life much less frustrating when you return to your plane months after the fact on another journey and having been for "walk about". I counted 28 Polar Bear going base and down wind once at Barter Island after Whale harvest by locals many were pink and likely I did not see them all. They must have come from hundreds of miles to be in that concentration.
 

blane.c

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But for practicality of bush plane for those who haven't pushed and pulled their guts out like I have when in the muck and mire or in deep snow, handles, handles, handles for the love of god put some handles on the **** thing.
 

wktaylor

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MAP... CAUTION/WARNING...

Composites gain strength when they are cold, metal gets brittle and may break sooner.
is principally incorrect.

In my humble EXPERIENCE, deep cold is far more fearful and difficult to 'manage' than high heat.... especially non-metallic and organic materials... resins, sealants, rubbers, plastics, fluids [fuel, lubricants, moisture, etc]… become very critical design issues. The 1950’s jet I currently work-on was designed for a static thermal range of -65F to +160F. We have ACTUAL external temperature measurements of -100F [arctic night] to +185F [parked in the Saudi desert daytime]. In real terms, though some parts of the wings, stabilizers and struts actually experience heat spikes to +225-to 275F with engines running. The slightest drop of moisture becomes rock-hard and expands as it freezes... and on the other-extreme expands and turns to gas as the temperature rises to/above boiling... where it experiences sudden transition from a liquid to a gas.

Alloy/carbon steels are notorious for brittle fracture at arctic temperatures... however aluminum, most stainless steels, titanium, etc... tend to get stronger and tougher at extreme low temperatures.

Resin matrix composites tend to be more more-brittle at very low temperatures... due to the properties of the resins [thermosetting plastic]. Only a few very expensive thermoplastics retain strengths at the extreme low temperatures of the arctic.

Likewise most metals have predictable mechanical properties at higher temperatures, while resin matric composites tend towards radically poorer strength at higher temps... due to softening effect up to 'glass transition temperatures. Oddly, plastic resins that perform well at extreme low temperatures usually perform much better at higher temps. These VERY expensive reinforcement plastics retain strengths at the extreme low temperatures of the arctic and extreme desert temps... but have 'special processing' needs/procedures.

As for repairs to composites at very low temperatures... epoxies are 'thermosetting' which mandates heat input for 'cure' [chemical cross-linking to build permanent/strong resin-bonds]. MOST plastics can be be repaired with epoxy or polyester thermosetting resins... assuming the resins have added heat and/or are exothermic [generate heat thru the chemical reactions] during cure.

In metal structures, the primary thermal issues between -100F and up-to +250F is dissimilar metal expansion expansion/contraction.

NOTE. This is why paints, sealants, rubbers, lubricants, etc must be to specified to survive/perform while exposed to real-world wild temperature swings.

Enough. I hope this make sense, for now. I'm tired.
 

blane.c

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There were a handful of times that going into Deadhorse we were indicating 120 knots but groundspeed was 50 knots this dissipated descending between the five mile fix and touchdown to around 35 knots headwind component at touchdown.

Spoilers could be very handy to keep a small aircraft "planted" after touchdown. People frequently do not value enough the ability to kill unwanted lift.

In the USA there are three paved runways north of the Arctic circle, Kotzebue, Barrow, and Deadhorse.

Most of the others are gravel or ice or mud/grass (some kind of short grass like vegetation interspersed with the mud) and in the summer the Arctic can be very muddy around airport environments. While I have seen pink Polar Bears I have also seen brown one's from chasing prey in the swamp which is fundamentally what the "tundra" is in the summer.

Mud and Ice are problematic for aircraft operations both airborne and on the ground and must be experienced to be fully appreciated.

For your design considerations.
 

Jonny o

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Bears frequently molest anything that has any trace of blood on it. They have sense of smell far beyond our capability and will chew on most anything that has a drop of scent on it. Many have lost vehicles, property and been injured or killed for lack of appreciation of this fact. Care to put everything into the plane so it won't leak fluids will make your life much less frustrating when you return to your plane months after the fact on another journey and having been for "walk about". I counted 28 Polar Bear going base and down wind once at Barter Island after Whale harvest by locals many were pink and likely I did not see them all. They must have come from hundreds of miles to be in that concentration.



Hmmm. Now that is ironic. I came in for a break working outside, at -32, here at BARTER ISLAND , ALASKA and opened up homebuiltairplanes.com to enjoy my coffee with.

AIRGLAS has been making both carbon and fiberglass skis for airplanes and military helicopters, up here for 30+ years. They bond the UHMW to the bottom of their composite skis.

F ATLEE DODGE has been making carbon skis for Supercubs for at least 15 years. I have been torturing a set for a long time on my trapline and out wolf hunting at temps past -50.

CARBON CONCEPTS makes a huge number of non certified carbon parts: skis, belly pods, flaps etc.

Aluminum skis work, but without a 3/8 thick UHMW bottom skin they will stick to the snow. A friend tried to ferry his airplane to another strip to put on new bottoms. I took off in 100 feet. After 1000 feet he shut it down and gave up. If you leave metal skis overnight on the snow they will have a dense coat of course ice crystals on the bottom. The same result, as above, will be made even worse.

For bush operations engineering calculations are helpful as a minimal spec., but durability is what rules the design. Any component that can't take a medium, several minute pounding with a 2 pound deadblow hammer, at -20 is not going to last long. That's what is happening on each crusty, broken ice chunk, take off. The floor protector on the battered Cessna 207 flying in and out of here is 3/4 plywood !

I taxi through brush, as thick than your thumb, all of the time, and my Atlee skis keep on truckin'.
 

gtae07

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. -40 is a temperature many wait to see before venturing out and is not considered a limitation with the people I flew with. I have seen -65 on the thermometer with "brisk" winds
negative C temperatures which we still consider warm here.
ACTUAL external temperature measurements of -100F [arctic night]
working outside, at -32,
NOPE

I often ask myself what possesses people to make them want to live somewhere that gets that cold. Then I stop, and think "if they didn't, there'd be more of them down here and it would be even more crowded". That usually gets me to stop wondering. Because with more people that would mean more towered fields, and that's just no fun.

It was a pleasant 75 ish on New Years here...
 
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