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Bob Brock
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Posted Sunday, January 15, 2012 @ 09:55 PM  

Greetings.... below is a link to a very short album of new shots, and a new dolly that seems to be working out great. Hope this is the last dolly until the wings are mounted. Collin will have the engine done in a few weeks so I want to be ready to mount it to the fuselage. I guessed on the balance points but hopefully the engine will fit and not tip over... or I can add some wt. to the tail. Being able to work on the fuselage in my garage is wonderful. Hope you like the use of my pilots license... actually an old license.

https://picasaweb.google.com/lh/sredir?uname=Bomar1&target=ALBUM&id=5698031784347501889&authkey=Gv1sRgCMPOk8nY74DLcA&feat=email

more later... thanks everyone...

dannparks
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Location: Parkside Airpark, Battle Ground, WA
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Posted Sunday, February 5, 2012 @ 02:42 PM  

Glad to see your continued progress.

I like the idea of replacing the deformed gear attachment bolts with larger US versions (my bolts are a mess). Since I see it mounted, did you have any problems putting larger nuts on the inside? I remember it was pretty tight in there with the wrenches. Also the original bolts have a notch on them that locks to the backing pate which allows you to tighten (re-tighten over time) the bolts with the wing in place. Have you figured a way to lock the bolts, or just given up on re-tightening?

Also, I would be careful about your jig putting too much twisting torque on the wing attach plank in the fuselage. It doesn't see that kind of force transfered to the fuselage in the plane with the wing attached (landing gear forces are transfered to the wing, not the fuselage). Putting the engine on the front will really tweek it. You might look at bracing the jig to the rear wing mounts as well to reduce the twist on the plank. Just to be safe...

--------------------
Dann Parks • RF4D #4051 N2188 • now flying!
Pictures at: https://picasaweb.google.com/111628310900713778468/RF4D_N2188?noredirect=1

Bob Brock
Master Sergeant

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Posted Wednesday, February 15, 2012 @ 01:47 PM  

About NUTS....

Why don't we get rid of English and go with metric??? What a mess here in the US when we want a 5mm castle nut in fine of very fine threads and all you can get (without ordering hundreds) are course threads? Anyway, I have a few questions regarding the engine mounts... bolts and nuts.

1. The 5mm bolts with hex heads that go through the firewall... then pass through the 4 hole backing plate, are fine threaded and use a castle nut with cotter pin... OK, I have all the original bolts and nuts but it seems impossible to get a cotter pin into the top bolts that hide in front of the gas tank (and I am not going to take out the tank). I drill the holes a little larger and replace the bolts and nuts with AN... but..... why not use a stop nut or elastic stop nut back there?? I don't understand the use of a castle nut and cotter pin (even if I could get the right size). My understanding is that a castle nut and cotter pin is used where the nut is NOT torqued down... thus allowing some movement. Is it used in that application because the wood moves?? And if so, how tight should the castle nut be on the bold?

2. Engine mount, horizontal bolts and nuts holding the aluminum mounting blocks (with engine mount/bushings).... these are 5mm (course) bolts with a shear nut (shorter and more squared off than the taller castle nuts... using a 1 mm cotter pin... (the only size I can find that fits). So here is the question.... do you have to use a shear nut in that application? If so, how tight do you make it? And if I have to go to an AN (I asked a suppler what AN stood for and he told me Army/Navy... it that true?) should I use a shear nut or a metal stop nut? As you all know, there is not much clearance with the nut heads (sorry I could not use the bolts Eugenio gave me with the hex key head)...

3. Like most assemblies I am getting better at standing on my head, using a mirror, and forceps to install cotter pins. Seems like I do everything three or four times to get it right. But... it is OK to use stainless steel safety wire rather than cotter pins? If so, what it the technique for twisting the wire... do you for example bring it to the front, put in 4 or 5 twists and then bend it back after cutting off?

Regarding the dolly.... I do have more support in mind when I mount the engine. We have many new engine parts.. like cylinders, pistons and between Collin and I, we found some good '65 heads that Collin is reworking (German valves), etc. I am sure he will have more on the engine... but we are getting there. Collin is really, really exact on engine parts (they all have to match, even down to the casting batch) which is great because I would not have a clue.

The panel is more work than I thought.. actually everything is more work than I thought!! Thanks to Eugenio, Dann, Collin and lots of others, I used their panel layouts as samples. Another friend just finished his panel so I am using his experience with the CAD program and laser cutting to get mine done. The biggest problem is of course panel space along with the space behind the panel for clearance. I think I will have a few changes that will be interesting and I will have an album on the panel. Collin loaned me his wheel cover so I can see how mine should fit. I didn't realize how extensive the rebuild would be... the final 20% takes 50% or the time.

It will fly this Spring...

Today I am taking some 10mm x 200mm engine bolts to Collin and the spark plug connectors Eugenio gave me so we can use auto fine wire plugs.

Bob Brock
Master Sergeant

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Posted Wednesday, February 15, 2012 @ 07:03 PM  

more on nuts....

I talked with the two IA's and one A&P today answering some of my questions. Basically they told me the use of a castle nut and cotter pin were used where "the bolt protected rotation," i.e., the bolt was expected to rotate or the bolt was through a casting where you did not want to put torque pressure on the casting (lots of glider parts are into castings). They could not see a reason for using a castle nut on the engine mounts where the back of the bolt is inside the firewall and recommended using an AN 3-16 bolt with washers and an elastic stop nut. The horizontal 5mm bolts (two for each engine mount) are a little trickier.. but if it were to use an AN bold (perhaps drill out to AN-4... 1/4" they recommended a metal stop nut that should only be used once and then the bolt and nut should be replaced (metal for higher heat environments).

Regarding hardness, they suggested going with about the same hardness as the original bolts... the thinking was that if you go too hard they are more brittle, but it depends on the application and how much shear is involved. Replacing the 5 landing gear bolts as I did earlier with a harder bolt was not seen as a problem because they are slightly over-sized, i.e., going from the original (about .225 inch) to AN4 (1/4" or .25).

Please let me know if any of this sounds incorrect. I want to make the rebuild at least as strong as when it left the factory... and perhaps a little stronger in some places that showed weakness like the wing trailing edge.

Cheers,

Bob Grimstead
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Posted Thursday, February 16, 2012 @ 01:40 AM  

Hi Bob,

I'm sorry, but I haven't been able to read all this post in detail, (I'm in a bit of a hurry today) but when you're looking for metric bolts with fine threads, have you tried Allen screws? Maybe they're called hex-head cap-screws or something in the USA, but I mean the 'bolts' with hexagonal sockets sunk into their heads, in which you use a hexagonal bar we British call an Allen key.

In many places in our three Fourniers, Matt & I have been able to find metric Allen screws to fit, where we could not find proper metric bolts.

One of the biggest problems is that Fourniers used an old 1960s French standard of bolt which is no longer manufactured anywhere, so nowadays the ratio of shank to thread is no longer correct, so we've ended up buying several bolts or Allen screws of the correct diameter and slightly longer shank length and either cutting the thread a lille longer (where they are not highly stressed or very important) or just using lots of washers to take up the slack. Then we have to cut off any remaining excess end thread, because Rene so often squeezes these bolts into tiny spaces where there is little spare room.

You have our sympathy, but rest assured, we've both been there before you. Sourcing and modifying all the little bolts consumed most of the time taken for G-AWEK's prolonged rebuild.

And then you have to drill all the tiny 1/16" holes (or even smaller 1mm holes) through the Allen screws for the split cotter pins. After losing lots of Allen screws with the ends of hard drill bits snapped off and permanently embedded in them, we graduated to cobalt bits, which although expensive work a little better and last rather longer.

Good luck, and be patient. You'll get there.

Yours, Bob

--------------------

Bob Brock
Master Sergeant

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Posted Friday, February 17, 2012 @ 11:10 AM  

Eugenio gave me a large package of metric bolts that use hex keys. Of course at the time I did not know exactly how valuable these would be in the rebuild.... but in all things Eugenio, his experience was invaluable. By the way, I found a neat way to drill the holes in the bolts... I start by setting up the mill with a very small center drill... it doesn't wobble and break like those small drill bits, then after the hole is well started the regular metal drill bit does the rest of the job.

Regarding the horizontal bolts holding the engine mounts to the brackets on the firewall... are those bolts free to rotate or should they be torqued down? And if they are torqued down, why not use a metal lock nut?

Whenever possible, I have tried to stay true to what Rene' designed and if he used a castle nut and cotter pin, I do too. After trying something a dozen different ways (like with the panel) I come back to the original design with greater respect for what Rene' accomplished.

Markku
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Posted Monday, February 20, 2012 @ 10:34 AM  

Hi Bob
I think I have in my plane only metric bolts with coarse thread M4, M5,..., fine thread bolts are indicated: MF4, MF5....., I'm not familiar with that French standard.
When I got the new engine mountings from EIS, they came with the bolts (aviation bolt std. LN9355).
Bolts trough the fire wall are in my and our club plane done with Nyloc nuts
eugenio
First Sergeant

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Posted Tuesday, February 21, 2012 @ 03:47 PM  

All bolts used on Fourniers are ISO standard coarse thread (also called MA) Fine thread bolts (MB series) are not used in aircraft.
The bolts for aeronautical use (those with short thread like AN/MS standard) are the LN series, still in production, but very hard to find.
The easiest way to go is like Bob Grimstead suggest, and what has been done for decades from gliders manufacturers, take the bolt with the grip you need then cut the thread to fit your need.
I can assure that still today some manufacturers do like that. I found all bolts like that on a certified Tecnam P92.

Eugenio

Bob Brock
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Posted Wednesday, February 29, 2012 @ 03:48 PM  

First.. thanks again for all the wonderful assistance. As I have said a number of times, there is no way I could do this project without lots of help.

OK... here is an update with some images. I have taken advice and used AN bolts where I could and some of the original or bolts from Eugenio where needed. My goal is to make everything at least as strong or stronger than when the aircraft left the factory without adding to the wt. It will be interesting to find out what the final wt. will be when everything is put together. Just in case it is up a few pounds, I am going on a diet to get off some pilot wt.

I removed over 6 lbs of wire, tubing and strobe transformers (and an old navigation system/ radio, etc.) and replaced with very light wire for the LED lights. So there will not be any high voltage devices in the aircraft. Hope you enjoy the images... here is the album link.

[Edit by Bob Brock on Wednesday, February 29, 2012 @ 03:49 PM]
https://picasaweb.google.com/lh/sredir?uname=Bomar1&target=ALBUM&id=5714631911290651825&authkey=Gv1sRgCJDJtcDnuPyuVw&feat=email

[Edit by Bob Brock on Wednesday, February 29, 2012 @ 03:52 PM]

[Edit by Bob Brock on Thursday, March 1, 2012 @ 11:15 AM]

eugenio
First Sergeant

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Location: Str. Val S. Martino inferiore 133/7 I - 10131 Torino ITALY
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Posted Thursday, March 1, 2012 @ 02:05 PM  

Bob, please don't use vynil tubing (or similar) for the instruments as you do in one of the last pictures, use only nylon/rilsan for the lines back and forth the aircraft, and silicone tubing for connecting the instruments and the probes. It is much more leak free, does not harden, is easier to disconnect and it works much better.

Eugenio

Bob Brock
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Posted Thursday, March 1, 2012 @ 07:05 PM  

The instrument in the album and tubing was for size only... I wanted to use the nylon tubing I got from Aircraft Spruce (label) ... then went to silicone for the connections.. have not done the instruments yet. Thanks for mentioning the problems with plastic lines. Getting everything to fit is a challenge and knowing what to order means that I will have lots of extra parts. Regards,
Bob Brock
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Posted Tuesday, July 3, 2012 @ 09:27 PM  

Here is an update... I wanted to fly to Minden this weekend, but every working full time for the past two weeks, I could not get it done. It seems the more you try to make it go faster, it actually goes slower. The ailerons have proved to be a challenge.. but I have them on but not bolted. I think they were individually fitted and I did not get them back on (in the wings) in perhaps the exact order... they were close, but not exact. I also have a few minor clearance issues where I need to allow for more clearance... somewhat minor.

Ok, now for the total weight. Sorry I did not weight the aircraft before I started the rebuild so you can tell me if I gained too much weight with fiberglass, fabric, paint, etc. It comes in a shade over 600 lbs.. total... perhaps 620. The attached album gives you the update and it also has images of the props I picked up today. More later... getting ready to fire up the engine again, do the annual and fly. But like pancakes, it will be done with it is done.

https://picasaweb.google.com/lh/sredir?uname=Bomar1&target=ALBUM&id=5761104777730996305&authkey=Gv1sRgCOWi27SCpOTxMQ&feat=email

Cheers, Bob

eugenio
First Sergeant

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Location: Str. Val S. Martino inferiore 133/7 I - 10131 Torino ITALY
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Posted Wednesday, July 4, 2012 @ 02:40 PM  

620 lbs is fine, if fully equipped. Usually with full instrument they are within 610 and 660 with some fitted with Limbach 1700 and electric starter reaching 680 lbs.
Take note that most of these motorgliders fly overweight, it's normal and when Ren้ was asked if it was the case to increase officially the MTOW he said it was possible, but too much papers had to be done and lots of money spent. Anyway he said there's no problem to exceed the weight, the aircraft has a very high safety factor.

Eugenio

dannparks
Sergeant Major

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Posted Saturday, September 1, 2012 @ 11:02 AM  

Hi Bob. How's flying and testing going? Have you had a chance to try the different props?

--------------------
Dann Parks • RF4D #4051 N2188 • now flying!
Pictures at: https://picasaweb.google.com/111628310900713778468/RF4D_N2188?noredirect=1

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