Brodhead Pietenpol Association

Original Posted By: FTLovley(at)aol.com
One of the big reasons BHP changed to the split gear was it's superior performanceon unprepared fields. I'm building the axle gear but it can really foul upwith long grass, weeds or crops on a rough field, and can contribute significantlyto a nose over whereas the split gear is much less likely to do this. Though Larry Williams airplane was actually saved from a nose over by his axlegear during his off field experience when he taxied into a hidden hold and theaxle caught on the edge of the hole thereby stopping the wheel from going allthe way in. He swears he would have gone over it it had been a split gear.The split gear is also lighter and less draggy.I don't think it is necessarily stronger however.I noticed an interesting thing on a friend's split gear recently. His cross fusalagestraps run on the outside and have bowed our away from the fuselage aboutan eighth of an inch, he couldn't figure it out. But what's happening is this.With a split gear, during a hard landing, downloads are delivered throughthe lift struts to the lift strut/gear fitting in combination with a downwardpull of the opposite bungee. So basically both side gear/strut fittings arebeing pushed down rather hard and there is nothing to counteract this.In a axle gear design, the X bracing and the legs themselves actually form an upsidedown "pylon" or truss which resists any upward or downward pull from thestruts. In conclusion, I think the split gear is more efficient and clean and less likelyto cause a nose over by picking up weeds, the straight axle is stiffer andcontributes to the overall rigidity and strength of the airframe..02 $________________________________________________________________________________

Original Posted By: Rick Holland
Subject: Re: Pietenpol-List: gear legsThe explanation for the bowed cross strap on the bottom of the fuselage is much simpler than all the engineered down loads and cross loads etc...after thefirst few hard landings, the wooden fuselage simply compresses slightly and isslightly narrower than it was when the cross strap was welded to the gear/strut fitting. Since the strap doesn't compress like the fuselage, there isnow excess length, hence the bow. On one of the original airplanes that I rebuilt,Bernard had bolted a steel ruler across the fuselage between the fittings as across strap, and it's still there today.Forrest Lovley________________________________________________________________________________Date: Tue, 14 Dec 2004 07:48:13 -0700

Original Posted By: "Clif Dawson"
Yup Clif, agreed. I wasn't really thinking about isolating the cables and their structural properties when I typed that. As I see it, the cables are great for tension and helping keep all the compression elements lined up nice and straight....zero direct benefit themselves in tension..... Kinda reminds me of years ago when I worked at an engineering company that built offshore platforms...they used some cable (for tension) in combination with some heavy wall pipe (for compression) to come up with some strange looking but incredibly strong structures.....hey wait, I wonder if you could actually fly an Air Camper over open water?!?! Hmmm, oops, I digress.....Actually, this landing gear thingy has become one of the more interesting aspects of this project! And that's partly because of the opportunity to learn from concepts like those discussed in your links below. VERY interesting. I love this learning process!One other benefit....I love the way the straight axle landing gear looks!!Thanks for the clarification......Jim in COLD Plano.....----- Original Message -----