What differences should I expect going down 20sqft on the same canopy model? (Fusion 210 -> 190)

[grue 1]

More responsive I'm sure, but what else should I expect? Any input appreciated.

Wingload will be going from 1.24 to 1.37, for reference.

cavete terrae.

[Pendragon 1]

Most notable difference with that change (~10%) will be speed.

- It will be faster on landing
- Sink rate will be higher (but you'll have higher forward speed remember! )
- Glide ratio will be about the same (need big change to make noticeable difference to this)
- Control lines are shorter, so less input required (for turns and flare)
- Riser pressure should be slightly lighter

In more general for a downsize, but not noticeably applying to a more docile design like the Fusion:
- More sensitive to harness input (although that canopy isn't very sensitive to that anyway)
- Because of heightened sensitivity, more likely to develop line twists/spin up on opening

Not a bad downsize progression at all but, without any knowledge of your landings, impossible for anyone on here to judge your suitability. I would suggest one thing though: regardless of your ability, make sure you are current when you downsize. Risk of hurting yourself (always present when you move to an unfamiliar wing) will be mitigated to some extent.

Don't think I've missed anything?

Have fun!
Richard

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BASE #1182
Muff #3573
PFI #52; UK WSI #13

[ryoder 1,590]

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- Riser pressure should be slightly lighter

The sum of the pressure on all four risers is equal to your body weight. How would canopy size change that???

"There are only three things of value: younger women, faster airplanes, and bigger crocodiles" - Arthur Jones.

[Pendragon 1]

Quote

The sum of the pressure on all four risers is equal to your body weight. How would canopy size change that???

Depends how the weight is distributed between the risers.

See: http://www.makeithappen.com/spsj/yourcan.htm

Actually, it's rather a good article.
I stand corrected; riser pressure should increase with wing-loading (like toggle pressure)

Richard

--
BASE #1182
Muff #3573
PFI #52; UK WSI #13

[Pendragon 1]

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The sum of the pressure on all four risers is equal to your body weight.

Not quite. The force is equal to body weight, but not pressure.

Pressure = force / area and, since area is decreasing (downsize), pressure must increase.

Richard

--
BASE #1182
Muff #3573
PFI #52; UK WSI #13

[ryoder 1,590]

Quote

Quote

The sum of the pressure on all four risers is equal to your body weight.

Not quite. The force is equal to body weight, but not pressure.

Pressure = force / area and, since area is decreasing (downsize), pressure must increase.

Richard

You are mixing apples and oranges. We are talking about riser pressure, not pressure per square foot on the canopy.

Yes a smaller canopy will be developing more lift per square foot of area, but basic physics tell us that for a canopy descending at a constant rate, the force gravity on the load (weight) must be matched by the force of lift generated by the canopy. That force is applied to the load via the risers.

Changing the size of the canopy does not change the total riser pressure. Changing the design of the canopy or just it's line attachment points can shift the fore-aft distribution of the weight, but the sum of the riser pressures must always match the weight of the load.

"There are only three things of value: younger women, faster airplanes, and bigger crocodiles" - Arthur Jones.

[genoyamamoto 0]

Quote

Quote

- Riser pressure should be slightly lighter

The sum of the pressure on all four risers is equal to your body weight. How would canopy size change that???

You are correct that it doesn't. But the response of a smaller canopy to a change in the weight distribution amongst the risers, for example, can differ. That's why you can do pull ups on a navigator 260's front risers and not change a damn thing while doing the same will produce a noticable effect on a canopy 100 sq. ft. smaller.

Gotta go... plaything needs to spank me
Feel the hate...
Photos here

[Pendragon 1]

I appreciate what you are saying; if I hang from a rope, the force on the rope is the same whether it is attached to a bridge or a tree.

However, when you pull, for example, a front riser down, aren't you effectively deforming the wing, which requires the pilot to overcome the pressure inflating the wing (which we have already established is greater on the higher w/l canopy) resulting in higher riser pressure?

Open to suggestions...

--
BASE #1182
Muff #3573
PFI #52; UK WSI #13