Shoulder Belts on a Baby Ace

[SVSUSteve]

As a side note, I would go with a "roll bar" type cross tube that is flatter on top rather than the 'A' shape in the drawing. Think of it as an inverted 'U'. That provides a bit more area for the forces to be spread out if/when the aircraft flips over. It's less likely to dig in and thus makes it a bit less likely that your head would strike the ground as a result.

 

[Vigilant1]

As a side note, I would go with a "roll bar" type cross tube that is flatter on top rather than the 'A' shape in the drawing. Think of it as an inverted 'U'. That provides a bit more area for the forces to be spread out if/when the aircraft flips over. It's less likely to dig in and thus makes it a bit less likely that your head would strike the ground as a result.

I assume those two cabane members are attached, at their apex, to the rear truss of the wing. If so, that rear truss should perform that load-spreading function you describe.
One thing to look into is whether those two tubes, along with anything else they are attached to, are sufficient to take the expected large loads from a pilot flung against those straps with a lot of force.

 

[Riggerrob]

Dear SVSUSteve,
The OP's sketch includes a horizontal steel plate to reduce the risk of sinking into soft ground. Your advice is still valid for low-winged airplanes. A friend installed a similar roll-bar (with a flat steel plate) in his all-wood Chilton.
Mind you, with an entire parasol wing, the risk of a Baby Ace sinking into soft ground is minimal.

 

[SVSUSteve]

I assume those two cabane members are attached, at their apex, to the rear truss of the wing. If so, that rear truss should perform that load-spreading function you describe.

Noted. I was just thinking about reducing the tendency of the "point" to dig in rather than the transmission of the load into the rest of the frame. I looked at that and just thought of it as akin to the point on a Danforth anchor when it contacts mud or other soft soil.

 

[Riggerrob]

Dear Little Scrapper,
Holy parts-count Batman!
You could do the same job with a simple loop of webbing. You can pre-sew the webbing and slip it over the cabane struts before you bolt on the top wing. The horizontal strap only needs to prevent shoulder straps from slipping below your shoulders. Who cares about upward loads?Parts-count = 1.
I still recommend routing a steel cable back to anchor near the tail wheel. That way-back anchor point provides a better angle to reduce vertical loads on your spine.

But that is just the opinion of an old parachute rigger ... and even older helicopter mechanic. Yes, I know how to use a torque wrench, but am much quicker on a sewing machine.

Also, a crotch strap (fifth point) will keep the waist-belt in place and reduce the risk of you falling upwards (negative Gs, roll-over, etc.).

 

[fly2kads]

View attachment 103874

Setting aside the question at hand...I just have to say that's a fine looking Baby Ace!

 

[Little Scrapper]

Dear Little Scrapper,
Holy parts-count Batman!
You could do the same job with a simple loop of webbing. You can pre-sew the webbing and slip it over the cabane struts before you bolt on the top wing. The horizontal strap only needs to prevent shoulder straps from slipping below your shoulders. Who cares about upward loads?Parts-count = 1.
I still recommend routing a steel cable back to anchor near the tail wheel. That way-back anchor point provides a better angle to reduce vertical loads on your spine.

But that is just the opinion of an old parachute rigger ... and even older helicopter mechanic. Yes, I know how to use a torque wrench, but am much quicker on a sewing machine.

Also, a crotch strap (fifth point) will keep the waist-belt in place and reduce the risk of you falling upwards (negative Gs, roll-over, etc.).

The guy who owns this owns a water jet company so for him it was quite easy.

I’m considering welding a round tube across the cabane structure.


Still working on anchor points. I need to order a belt set up and I’m not sure what I’m gonna do here.

 

[cluttonfred]

I like the idea of a loop around the top of cabane strut for the anchor. Simple and effective. How about one foot of 1/4” SS flexible control cable (6400 lb breaking strength), two thimbles and two nicopress fittings for the ends, and some clear heavy vinyl tubing to prevent chafing?

 

[lakeracer69]

Here is how it is done on my Lil Bitts. A .063 plate welded to the longeron and a frame for the turtle deck structure.
(One side only). The black pen shows the 1/8 cable that goes from the welded plate, lower right, up to the left where it attaches to the shoulder harness that drapes over a cross tube in the turtle deck behind your head. Pretty simple and gets the job done.