SP140 hang angle problems

GliderPilot · August 17, 2022, 10:44pm

I agree that your hang points are way too low. You basically moved the collars down a few inches while achieving less than half an inch backwards. That is not a good position for all the reasons stated above. Please do not attempt to fly with your collars that low! If you throttle up in that position it would not only dump you out of your seat but you could line twist the opposite direction.

What is your angle if you move your collars to the top of that straight section (the section which is almost vertical in your picture)?

Bartlett41 · August 17, 2022, 11:15pm

I am 196lbs…Hang test on iris arms with the soft links as far back as they can go was 14* sitting relaxed and 12* with legs extended and 10* hanging out of the seat ready to land.

JeffG · August 18, 2022, 1:42am

With the collars positioned at the first straight section of the bars, just after the downward bend, the hang angle is 24*. I’m 5’9" and 175 lbs.

grigsby · August 18, 2022, 1:53am

Well they certainly look badass. Based on your weight (you’ve got 30 lbs on me), I don’t think they’re going to improve my hang angle at all. We’ll see. I’ve already ordered them, and I don’t like how the current collars and swingarms are working, so I’m sure it’ll be at least some improvement in the functionality.

grigsby · August 18, 2022, 1:55am

That’s about where I was. Is that with the soft link straddling the collar? Moving the soft link behind the collar improved the hang angle for me (to about 17 degrees), but made other things worse – e.g. now the soft link rotates out of position.

Bartlett41 · August 18, 2022, 3:51am

This is from the owner of iris…”BTW, there is one way to get one more hang position out of these swing arms in case anyone needs them. It can be accomplished by using longer riser offset spacers and tubes combined with Dudek Powerseat’s figure 8 backup strap. This allows the pilot to hang on the very back hole instead of in between the two back holes”

JeffG · August 18, 2022, 2:40pm

Pls excuse my ignorance, but what are “riser offset spacers and tubes” and “figure 8 backup strap”? I read through the Dudek harness manual and googles for info on the riser offsets but found nothing.

GliderPilot · August 18, 2022, 5:59pm

@JeffG, they are talking about the Iris arms and the torque compensation. The SP140 arms are bent sideways to compensate for torque. The Iris arms are straight with spacers bolted to the side of the arms to hold the soft links. The safety straps connect the harness to the carabiners in case the arms fail. Those straps have figure 8 shaped loops (red and grey).

JeffG · August 18, 2022, 6:23pm

Thanks @GliderPilot, that helps. I understood the context but was confused with the terminology. I don’t understand how that combination of gear allows the pilot to hang on the very back hole.

JeffG · August 18, 2022, 7:32pm

OK fellers, I’ve been working waaaay outside the box here trying to get an acceptable hang angle while staying within the constraints of safe collar placement and not introducing more problems with a potential fix. Please let me know why this arrangement is crazy. It seems reasonable to me but I’m lacking in experience.

The fix is pretty simple; connect bungies from the soft links to the hoop. The effect is to pull the top ofthe hoop forward. The measured strain on the hoop is ~9 lbs. The bungies don’t interfere with my arms, though they do hold the swing arms up when not in flight. I think the bungies would need to be replaced with something a bit more secure. I don’t have my reserve attached in this photo.

GliderPilot · August 18, 2022, 10:38pm

Are you thinking about buying Iris arms? If you do, just know there is an option (if needed) to connect to the rear hole instead of between the two most rearward holes. Have you looked at pictures? The soft links connect to two holes. He described connecting to one.

jsneeb · August 18, 2022, 10:44pm

That is an interesting outside the box fix. I am not sure I would fly it that way for fear of the bungie coming loose and going straight into the prop. Also when you unload the glider in flight, that is going to pull the cage angle forward as the force of the bungies remains mostly constant while your force in the risers decreases in a unloaded maneuver. Possibility of line to prop strike if that happens.
This also looks like a cumbersome thing to hook up every launch and then detach, but I guess that depends if you are disassembling your cage.

Can I ask if you have considered relocating your battery? I have suggested it often when this conversation comes up because it seems like everyone is always trying all these new labor intensive or costly ( Iris arms ) fixes, while the real issue isn’t where your hang point connects, but the fact that the battery is heavy and located too far back to be counterbalanced by a person weighing less than 180lb. Relocating the battery is the only modification I did to achieve 10-15 degree hang angle with the collar still within the bent part of the bars.

GliderPilot · August 18, 2022, 10:48pm

The hoop is intended to hold lines out of your prop and that’s all. It’s a pretty flimsy design but it’s sufficient for what it’s designed for. I wouldn’t use the hoop to hold your arms up.

Holding the arms up changes the connection relative to thrust line. So when you apply power it will tilt you back more. Angle with thrust is more important than angle without.

JeffG · August 18, 2022, 11:38pm

Thanks @GliderPilot. At this point I’m just trying to soak up everything that others have tried/suggested, so no, not considering buying Iris. The “option” you mention is exactly what I’m trying to understand. So far I haven’t found any pictures that show what the Iris dude is describing. All I know is that there’s supposedly a way to use just the last hole, I just don’t understand how it’s being done.

grigsby · August 18, 2022, 11:42pm

How does this arrangement feel during ground handling? It seems like it would be awkward or cumbersome with the weight of the battery hanging so low.

I think it would be hard to convince me that this modification is any less labor-intensive than the other things people are trying. It looks like it took a not-insignificant amount of work to mount the battery there and run new power connectors.

GliderPilot · August 18, 2022, 11:52pm

Sorry but that statement isn’t exactly true…

If an adult wants to teeter totter with a child you must change one of three things:
1) Move the adult closer to the fulcrum
2) Move the child farther from the fulcrum
3) Move the fulcrum closer to the adult which is also farther from the child.

The battery is too far back from what??? It’s too far back from the fulcrum which is the hang point. You can move the battery closer to the fulcrum or you can move the fulcrum closer to the battery but either way the fulcrum and battery end up closer together. You chose to move the battery while other people are choosing to move the fulcrum.

You could also say the pilot isn’t far enough forward. Forward of what??? Forward of the fulcrum. So you could move the pilot farther away from the fulcrum or you could move the fulcrum farther away from the pilot (which is also closer to the battery). Notice that if you move the fulcrum it changes the distance of the fulcrum from both the pilot and battery at the same time so a smaller change is needed.

There are several reasons why moving the battery isn’t ideal but that’s not my point and it works for you and that’s great. But please don’t bash the idea of buying new swing arms when it’s a much more simple solution (it’s two blots).

grigsby · August 18, 2022, 11:58pm

You’re spot-on with the physics of the lever. And you bring up an interesting idea that I don’t think we’ve been considering: moving the pilot. What about adding some (more) foam padding between the back of the harness and the frame? Essentially, moving the pilot forward instead of (or in addition to) moving the fulcrum backward.

GliderPilot · August 19, 2022, 12:07am

Thanks, I wasn’t suggesting that but it is an option. I actually added a back rest for comfort which I can share pictures of later. It subtracts about 1 degree from the hang angle without adding padding but you could add padding too.

GliderPilot · August 19, 2022, 12:11am

Haha, not that it matters if you aren’t going to go with the Iris arms but here is a picture of what I believe he meant. The blue would be the figure 8 strap and I think the spacers need to be longer because the strap is wider:

JeffG · August 19, 2022, 3:20am

Thanks @GliderPilot for the further explanation on the Iris one-hole setup. It helps. In retrospect, I should have said that I am not considering buying Iris at this time. When the dust settles it might be the best solution. Maybe the new OpenPPG arms will be as effective and hopefully less expensive!

Note1: Sorry in advance for the lengthy post, but there’s a lot going through my mind right now.

Note2: Just so everyone knows, I am at the tail end of my flight training. I’ve actually never flown a paramotor, hence my ignorance. Flying is happening soon, hence all my questions.

So, help me understand your comments regarding “holding the arms up”. I assumed that in flight the arms are constantly being held up by the wing. Is that not the case? In my testing the proposed connections are affecting a positive change, that is reducing the hang angle. I don’t believe the arms are being held up, though in my first post about this I did say that the bungies “do hold the swing arms up when not in flight”, with the qualifier “when not in flight”. Perhaps what’s really happening is that the bungie is moving the fulcrum (drawing on your earlier visualization @GliderPilot ). And the movement is more effective than moving the collars because the fulcrum is moving in the X direction instead of the Y.

Regarding connection to the hoop: I certainly concede that that plan shouldn’t be pursued. However, what if there were a rigid part of the frame that extended up in the vicinity of the hoop? If connecting to the arms isn’t prohibited, and the bungie (or link) is tied to that rigid member, what then?

@jsneeb, I appreciated your comments. I don’t understand what is meant by unloading the wing, or what type of maneuvers would do that. I actually did move the battery down to where you have yours, just to better visualize it. It seems like an effective way to better distribute the weight, but it certainly negates the advantages of having the weight up on your back and I know I’m gonna need every advantage I can get!

As a side note, I have to say that I am extremely pleased by the engagement, professionalism and willingness to share of this forum community. I’ve had just the opposite experience with other forums. So, thanks!