---------------------------------------------------------- Zenith701801-List Digest Archive --- Total Messages Posted Mon 01/18/10: 5 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 05:25 AM - Re: CH701 builders & fliers - Tunnel & Seat front questions (Randall J Hebert) 2. 07:36 AM - Re: CH701 builders & fliers - Tunnel & Seat front questions (Tommy Walker) 3. 08:47 AM - Re: CH701 builders & fliers - Tunnel & Seat front questions (johndread@aol.com) 4. 09:21 PM - Re: Fork tube analysis and prospective stainless steel substitute (Les Goldner) 5. 09:29 PM - Re: Fork tube analysis and prospective stainless steel substitute (Les Goldner) ________________________________ Message 1 _____________________________________ Time: 05:25:24 AM PST US From: "Randall J Hebert" Subject: RE: Zenith701801-List: CH701 builders & fliers - Tunnel & Seat front questions Keith I believe that is just showing the orientation of the objects that are riveted to the seat front 7-F-11-1. I didn't put anything else in. The section just to the left shows the objects that are attached to the seat front but there is no section from above that would show their orientation, so I believe they used that method to show that they are Ls Randall J Hebert Randall J Hebert & Associates, Inc Consulting Engineers Ph 337-261-1976 Fx 337-261-1977 From: owner-zenith701801-list-server@matronics.com [mailto:owner-zenith701801-list-server@matronics.com] On Behalf Of Keith Ashcraft Sent: Sunday, January 17, 2010 6:27 PM Subject: Zenith701801-List: CH701 builders & fliers - Tunnel & Seat front questions All CH701 builders/fliers, On page 7-F-11, in the center of the page, to the right of drawing 1&1A, there is a view showing the section of the tunnel mated with the seat front. I see there are 2-"L" that are shown about midway up on the inside of the tunnel. I don't see these depicted on any side views of the tunnel, and the assembly guides do not mention installing these. Any ideas? Keith CH701 - scratch ________________________________ Message 2 _____________________________________ Time: 07:36:36 AM PST US Subject: Zenith701801-List: Re: CH701 builders & fliers - Tunnel & Seat front questions From: "Tommy Walker" Same for me Randy. There will be an L placed on the outside of the tunnel to support the seat pans. Perhaps that is what is depicted in the drw. Tommy Walker in Alabama N8701T Getting close -------- Tommy Walker N8701 - Anniston, AL Read this topic online here: http://forums.matronics.com/viewtopic.php?p=282069#282069 ________________________________ Message 3 _____________________________________ Time: 08:47:01 AM PST US From: johndread@aol.com Subject: Re: Zenith701801-List: CH701 builders & fliers - Tunnel & Seat front questions Hi Keith; The "L" that seem to be shown halfway up the tunnel are the "L" that attach the front of the tunnel to the Seat Front 7F-11-1, what is shown is a cross section of the "L" along with the notation that the "L" is "Bend up" There is a stiffener that is applied to the Tunnel, it is shown on 7F-16 center right of the drawing. That "L" goes from the top of the seat front "L" to the aft end of the "L" that attaches the bottom of the tunnel to the floor. Hope that clears up any confusion. John Read CH701 - Elbert CO - Jabiru 3300 Phone: 303-648-3261 Fax: 303-648-3262 Cell: 719-494-4567 In a message dated 1/17/2010 5:54:14 P.M. Mountain Standard Time, ch701builder@yahoo.com writes: All CH701 builders/fliers, On page 7-F-11, in the center of the page, to the right of drawing 1&1A, there is a view showing the section of the tunnel mated with the seat front. I see there are 2-"L" that are shown about midway up on the inside of the tunnel. I don't see these depicted on any side views of the tunnel, and the assembly guides do not mention installing these. Any ideas? Keith CH701 - scratch (http://www.matronics.com/Navigator?Zenith701801-List) (http://www.matronics.com/contribution) ________________________________ Message 4 _____________________________________ Time: 09:21:07 PM PST US From: "Les Goldner" Subject: RE: Zenith701801-List: Fork tube analysis and prospective stainless steel substitute Thank you for the analysis Curt. Looks like Chris Heintz picked the best way to go from a weight, strength, and cost standpoint. FYI, when the front gear folded, (the one I posted a year ago) it did do some damage to the firewall, which also had to be replaced. From: owner-zenith701801-list-server@matronics.com [mailto:owner-zenith701801-list-server@matronics.com] On Behalf Of Curt Thompson Sent: Sunday, January 10, 2010 9:01 PM Subject: Zenith701801-List: Fork tube analysis and prospective stainless steel substitute On my plans built CH701, I have been polishing a few of the parts like the landing gear and front fork. I was wondering if I could replace the front fork tube with stainless steel parts and get a similar look. I would need to make sure that the replacement had the same strength as the original. So, with the help of my son, we did a SolidWorks analysis of a 4130N tube, 2 inch diameter, 21 inches long with a 0.065" wall. The top is solidly anchored and a force is applied horizontally at the bottom. Here is a link of the simulation video that SolidWorks made: http://www.youtube.com/watch?v=w8uamuysV_8 The video ends when the fork tube fails. It took a force of 540 lbs. As you can see, the tube bent a lot before it failed. If you make the fork tube stronger you are likely to move the loads elsewhere and it will break somewhere else. One thing comes to mind here, if you bend the front axle and lock up the wheel you are going to see a lot more than 540lbs. There was a picture on this list over a year ago that showed a bent fork tube after what was claimed to be a normal landing. I don't know how common this problem actually is. We substituted the fork tube with T-316L stainless steel in the simulation. It took a wall thickness of 0.250" before we arrived at a similar result. Since that would make the fork tube about four times as heavy, I have decided to stay with the 4130N of the plans. I may go up one notch in thickness of 4130N though. I might also replace the front axle with a solid shaft. On the shaft I have now, I machined bushings and welded them in place. Curt Thompson Redmond, WA, USA ________________________________ Message 5 _____________________________________ Time: 09:29:25 PM PST US From: "Les Goldner" Subject: RE: Zenith701801-List: Fork tube analysis and prospective stainless steel substitute JG, There were two scenarios re this failure after ruling out construction error (which I say no sign off). First, some small metal debris was discovered on the runway that may have impacted and contributes. Second, the student pilot was on his check ride with a flight examiner and was making a short field landing. Some speculated that she may have applied brakes before touching down, which would have made the nose wheel impact hard. The student pilot said this was not the case, but we know how nervous we can be in a test situation. Les From: owner-zenith701801-list-server@matronics.com [mailto:owner-zenith701801-list-server@matronics.com] On Behalf Of JG Sent: Monday, January 11, 2010 3:52 PM Subject: Re: Zenith701801-List: Fork tube analysis and prospective stainless steel substitute I once helped re-build a 701 that had hit a fence on take-off. A heavier nose leg had been fitted, causing the firewall to be damaged as well. Replacing the firewall is a MAJOR job........ A new nose leg and prop are much easier and less costly...... Don't know how you can bend a nose leg on a 701, even in a heavy landing scenario. The nose wheel should be way high off the ground at landing AofA, and the weight distribution should be such that you can hold the nose up after the mains take the weight. The vertical CofG of the aircraft is quite high, such that at the AofA at touchdown it effectively moves back and the aircraft nearly balances on the mains at that attitude. If you can't hold the nose up and it comes down hard, then either the horizontal CofG is way forward, or the main gear is canted back somewhat. The 'angle of dangle' of the main gear is often not noticed, but can vary due to wear or improper fitting of those rubber blocks. If the gear is angled back just a bit it puts much more load on the nose wheel. For real STOL use, especially on rough strips, it's best to try to have the weight on the nose wheel to be minimum. Fully loaded to aft CofG, if someone pulls the tail down to the ground, it should just about stay there. The angle of the main gear can be adjusted, often by just reversing those rubber blocks, or if necessary by grinding a slight taper on them with a course sanding disc in an angle grinder. But of course, first must get the CofG of the aircraft correct, by weight and balance measurements. JG www.stolspeed.com On Tue, Jan 12, 2010 at 7:18 AM, Curt Thompson wrote: Here is a link to the previous thread that has pictures of how the fork tube bent. http://forums.matronics.com/viewtopic.php?t=56639 &highlight=weak+701+nose+gear Curt ist" target="_blank">http://www.matronics.com/Navigator?Zenith701801-List tp://forums.matronics.com _blank">http://www.matronics.com/contribution ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message zenith701801-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Zenith701801-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/zenith701801-list Browse Digests http://www.matronics.com/digest/zenith701801-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.