Retractable Shoulder Harness

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Postby Chappy » Mon Mar 07, 2005 12:17 am

Shannon,

I should add that Dale Kramer really hated customer modifications to his design, like most airplane designers. Considering that I was one of the worst offenders back during his first couple years in business, I was always kind of surprised he asked me to come work for him. Over the years, with people making all kinds of changes and additions to their planes that affected them structurally or aerodynamically, some got hurt. The lawyer's bills started to pile up, and he came to dread hearing about modifications people would come up with.

Some that I remember: clipped wings for higher speeds and aerobatics(caused wing and lift strut failures and deaths), inverted wingtips (for more low speed lift, but reduced stability in turns), enlarged ailerons or full span ailerons (exaggerated adverse yaw making control difficult in marginal conditions), spoilers positioned indiscriminately on the wing, flaps (Dale got in BIG TROUBLE when a flap on a factory prototype experienced such sever flutter he was afraid he would have a wing failure!), extra tail surfaces, an extra engine mounted between the tail surfaces (gross CG problems, extreme changes in pitch control authority with large power changes, potential damage to the ruddervator's structure and hinges), multiple additional engines mounted rather far out on the wings (pilot workload, extreme yawing with an engine out), poorly designed pods and windscreens (that caused such downforce that at speeds below VNE the plane did not have enough elevator authority to pull out of a high speed dive). I'm sure I could come up with others. It's not that all modifications are bad or dangerous. It's just that they have the real potential to be IF they are not well thought out as to the effects on structure and aerodynamics. The implementation of modifications, as to how well they are actually done, is also very important and can make all the difference as to whether they are safe or not.

Ultralights in the USA are not certified airplanes, or even Experimental class, and as such we have an incredible freedom to work on and mess with them that no other class of airplane enjoys. As such, we have the responsibility to not abuse that freedom by doing too many dumb things.

Anyway, that's just my humble opinion... now that I'm much older and a little bit wiser.

Chappy
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Postby Guest » Mon Mar 07, 2005 2:07 am

Hi Chappy,

Very good points about highly modified Lazairs. Sad to see the same type of things going on today with a few Lazairs. Nearly all Lazair fatalities recorded have been attributed directly to owner modification. The few others for unknown reasons or pilot error.

Backtracking a bit earlier you made the statement " I know it's not a lot, but Lazairs do best when kept light, and too many little things end up really adding up."

In this statement you say a Lazair "does best" when it is "kept light". Again and for the sake of discussion your implication is that certain things can or should be omitted from a particular plane to preserve lightness. Lets take Georges plane for example since it is what started the discussion in the first place. His plane is an upgraded Series 2 equipped with factory spec wide gear, brakes, spinners, fiberglass seat, shoulder harness, wheelpants, Inst pod, box section stiffeners, long bolt engine mounts, sharp trailing edge, swivel tail wheels, large ruddervator pushrods, series 3 short tail, jury struts, and other minor structrual improvements. This plane is definitely not a light as it could possibly be however it does not incorporate anything that could be considered "excessive".

For the sake of lightness and best performance what specific items incorporated into Georges plane would be candidates for omission ? Basically what could he have done differently or live without to have "better Lazair".

This debate has been on-going since day-one with varying opinions on the subject. One Series 3 owner in particular that stands out in my mind advocated stripping off all the "unnecessary" weighty items. These weighty items included the brakes, wheel pants, spinners, gap covers, instruments, swivel tailwheels. Of course this plane also had no upgrades or factory refinements (capstrips, jury struts, large pushrods, or long bolt engine mounts) of any sort. This particular plane was indeed "light" but was it really a "better" plane all things considered ??

S
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Postby lazairiii » Mon Mar 07, 2005 12:00 pm

Chappy,

I'd like to stay on subject here. The original post was to show and highlight a "type" design shoulder harness and lap belt with integrated Inertia Reel retractor. This IS a light weight and very impressive design AM-Safe has developed for our specific airplane.

If you want to start a thread on the pro's and con's of different mods, then do it aside from a legitamate post. I feel you've taken this post completely off subject and distracted from the original intent.

My intent is to bring to the attention of the group a new and vastly improved shoulder harness set-up. You promptly shot it down. Honestly, I'd be more than happy to just construct my airplane in complete obscurity and fly it. However, I have taken, as many others have here, the time, effort and expence to go out and look for ways to improve this airplane. Now that's not to say as you have suggested, that all mods are safe. I'm not saying that, all I'm saying is that I am presenting this to the group for their individual evaluation. I would be willing to bet that Dale would approve of this set-up 100%. Any mod done to my plane is open to any Lazair owner for evaluation for safety and weight. I've done nothing stupid to my airplane, it is very straight forward and build very well.

I have done an estimate of the added weight with the "Factory Mods" I have incorporated into my plane. That total adds up to a whopping 5-7 lbs. Now add on the shoulder harness, another 8+ ounces, fiberglass seat and pad another 1 pound (over the weight of the original banana seat), and the P-tips which is negligable in weight gain. I weigh in at 170 lbs. Now If there are guys flying Lazairs that weigh 200+ then the measly weight I have added to my plane in upgrades and improvements will do very little to deter an incredible performing plane.

Guys, this Shoulder Harness set-up is presented with safety and weight defenately in mind. Consider it! Again, I do NOT benefit from this in any way, other that the knowlege I have helped to improve a needed area on the plane. This will work on all series planes and with either banana or fiberglass seats.

George Curtis
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Postby Chappy » Mon Mar 07, 2005 9:16 pm

Oh boy, I guess I've really done it this time.

George,

I am really sorry that you think I was being strongly critical of your design. I thought I made it clear that it was not my intention. I was only questioning the weight of the reel assembly, and saying IMHO that a standard 4 point harness was sufficient for our little planes from a safety point of view, and offered the advantage of weight savings. I should have left it at that, and not used it to preach the evils of weight and less than well thought out modifications in the same post, as they didn't apply in your case. Again, that WAS NOT directed at you, I thought I made that clear, but i guess that didn't make it through my rambling. I was just using it as a catalyst for discussion on mods and weight. Looking back on it now, I guess that was a mistake. I was upset too by your defensive response. My skills at communication aren't too hot, and sometimes my tone must overshadow my message. Part of it is that sometimes I write stuff late at night when I'm too tired to make good sense, but I hate it when I don't have the time to participate here. Also, I feel like all you guys are good friends now, and as such we should be able to discuss stuff without hurting feelings. I guess I have a lot to work on in trying to fit in here in this little community!

The only reason I stayed on the subject after your defensive follow-up post was because Shannon wanted to take the other part of my post and expand on it, which I thought was OK. I'm sorry if, again, you thought it was being directed toward you - it certainly wasn't. You are right, though, that we should have taken the discussion elsewhere, because it did give the impression that we were discussing the merits of your design. I apologize for that.

Shannon,

Let's explore this subject somewhere else, and maybe another time. I'm awfully busy right now, but I'd like to comment on the post about the Westlake engines, as that's something I had some involvement with while employed at Ultraflight (and has less potential of ruffling feathers, I hope).

Thank,

Chappy (in the dog house again)
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Postby JPXman » Tue Mar 08, 2005 3:47 am

on topic:

price george? how much are these babies, and do we have to fly to the factory to get them installed ;)
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Postby lazairiii » Tue Mar 08, 2005 12:42 pm

Hello Tyler,

Am-Safe's price for the adjustable shoulder harness with attached (detachable if you choose) lap belt is $199.00. Look back at my very first post on this and it shoudl be there. You do not have to fly to the factory to have it installed. You will be required to make yourself a short version of the G-8 bracket, drill and install the IR to that using floating nut plates and then mount that directly behind the existing G-8 bracket as you can see in the pics. I changed out my seat spreader angle bracket and fabricated one out of round tubing so the shoulder harness would slide smoothly under it. The lap belt is attached as you can see from the pics I previously posted. All in all it's a half-day project if you have the short G-8 bracket made, floating nut plates, bolts etc. ready to go.
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