Toggle pressure and what effects it.

[cosmicgypsy 4]

Hey guys I'm looking for some insight. What effects toggle pressure? Is it the trim, the load, maneuver? If you know of some good articles or books I'd appreciate that info too.

Thanks

Cosmic 

[nwt 18]

51 minutes ago, cosmicgypsy said:

Is it the trim, the load, maneuver?

Yes

[gowlerk 655]

35 minutes ago, nwt said:

Yes

But I would say the largest factor of the three is the load. And the speed would affect it as well. 

[RiggerLee 32]

It relates to load in the since that it will be a percentage of the load of the canopy. Load in this context is not wing loading but total suspended weight but is also controlled by g loading. If you are in a 2 g pull out the loading and control forces are doubled. 

 

Trim is a factor. The steeper the trim of the canopy the more the canopy will be front loaded. Nose down, front riser pressure higher. Flatter trimmed, front riser pressure lower. In terms of toggle pressure nose down means lighter toggles and flatter canopies heavier pressure. Some people will argue that the added airspeed of a steeper canopy increases the toggle pressure but I think they are confusing it with the g loading. To examine it rationally you have to look at the percentage of load on the toggles.

 

Lee

[Deimian 16]

6 hours ago, RiggerLee said:

Trim is a factor. The steeper the trim of the canopy the more the canopy will be front loaded. Nose down, front riser pressure higher. Flatter trimmed, front riser pressure lower.

That's interesting. Naïvely and without giving it much thought, I thought it was the opposite. The Katana, for example, is a notorious steeply trimmed canopy, and the front riser pressure is ridiculously low. 

[gowlerk 655]

5 hours ago, Deimian said:

That's interesting. Naïvely and without giving it much thought, I thought it was the opposite. The Katana, for example, is a notorious steeply trimmed canopy, and the front riser pressure is ridiculously low. 

Also my experience. Flat trimmed canopies like Stilettos have higher front riser pressure.

[wolfriverjoe 386]

 

15 hours ago, RiggerLee said:

Trim is a factor. The steeper the trim of the canopy the more the canopy will be front loaded. Nose down, front riser pressure higher. Flatter trimmed, front riser pressure lower. In terms of toggle pressure nose down means lighter toggles and flatter canopies heavier pressure. Some people will argue that the added airspeed of a steeper canopy increases the toggle pressure but I think they are confusing it with the g loading. To examine it rationally you have to look at the percentage of load on the toggles.

 

Lee

 

8 hours ago, Deimian said:

That's interesting. Naïvely and without giving it much thought, I thought it was the opposite. The Katana, for example, is a notorious steeply trimmed canopy, and the front riser pressure is ridiculously low. 

 

2 hours ago, gowlerk said:

Also my experience. Flat trimmed canopies like Stilettos have higher front riser pressure.

That's interesting. And also my experience.

I know better than to argue much with Lee about this stuff. 

But, on a 288 Manta, I could pretty much do pull ups on the front risers. The canopy would barely deflect, even though I was pulling up enough to unweight the leg straps. 

 

Yet I could do 180s or more pulling a front riser on a Triathlon 190 and a Sabre2 170

[gowlerk 655]

2 minutes ago, wolfriverjoe said:

I know better than to argue much with Lee about this stuff. 

Yes, I am also reluctant to disagree with him. But discussion what what we are here for.

[pchapman 83]

There are so many different factors involved, it gets confusing and I don't know the answers either.

Some variations:

1.  RiggerLee mentioned, "In terms of toggle pressure nose down means lighter toggles and flatter canopies heavier pressure."
I can't say how it is in general, but I recall one counter example. Have an old, large F-111 canopy (Titan 265) that I used to use for accuracy. It had high toggle pressure. I added an extra rapide link at each front riser (and even played with using 2 extras), so the canopy trimmed flatter and flew slower. The toggle pressure in turn went DOWN and was more pleasant to work in deep brakes.

2. Sometimes comparing a steep and shallow trimmed canopy is confounded by different styles and sizes of canopy. For example, one doesn't normally get to compare a (non-existent) Katana 280 against a Navigator 280. And is one comparing how much force it takes to pull a front riser down half an inch, or is one thinking of the final effect of pulling a front riser down?  After all, even if a small and large canopy have the exact same front riser forces, you might think, "Ugh, this big canopy is a boat, I'm hauling down the front riser and almost nothing is happening", while on the small canopy you whip nearly instantly into a sharp diving turn and even if you need a solid pull, you only need to do it for a second.

[Binary93 43]

I can compare JojoWings Raptor 135 (steep) vs Icarus World X-Fire 138 (shallow), I've recently flown both.

Raptor is very light on front risers and toggles are a real workout. On the other hand, X-Fire has much heavier fronts and the toggles are much lighter.

[riggerrob 139]

Changes in suspended weight definitely change toggle pressure.

For example, if I jump the same Icarus 360 tandem canopy with a light-weight student, then a heavy weight student, toggle pressure dramatically increases.

With the light-weight student I can practice rear riser turns and rear riser flares before unstowing brakes, Then repeat the control check after releasing brake toggles. I like to practice rear riser manuvers in case I suffer a jammed toggle some day. Knock on wood!

OTOH, with a heavy student, any rear riser manuver is like trying to bend a steel crow-bar!

Hah!

Hah!