Q:  What size are the hoses for high pressure brake line. (Steel Braided?) 

A:  -4 size here, straight ends. Hose cut lengths can vary, but I use a 10" length of hose on the brake line near the caliper, and you will have to determine the length for the master cylinder-to-bulkhead fitting on your installation.  Mark Frederick *end of comment*

I put together some instructions on how to modify and use the bleeder.  The bleeder bottle is a "R L Flowmaster Home And Garden Sprayer Home & Garden Sprayer Model 1998.

Check pedal pressure, it should be quite hard, and check for leaks.  That's it.   Garry LeGare *end of comment*

I visited Jim Winings and Bob Japundza on 2/1/03 and picked up my new Indy mount.  It is a work of art.  I am quite impressed with the workmanship and the thought that went into this mount.  You can see it in the photos below.  The old Mk 1 with gussets is on top of the Indy mount.  As is obvious in the pictures below, the socket is substantially thicker, the tubing size is increased in several areas as shown in the first picture by the white arrows, the tubes that the firewall bolts go through are twice as thick, and the upper corner weld clusters are no longer cantilevered out from the firewall but are right next to it.  Also the gussets that support the bolt tubes in the lower corners are 0.1" thick.

Jim Winings also explained that the engine mount pads, the ones that actually touch the rubber Lord mount donuts, were adjusted slightly on the new mount to eliminate a built in need for additional unnecessary washers.  Hard to explain in text but easy to see in person.  Vince  *end of comment*

  If the Indy mount doesn't work, I've got my own design shown here.  LOL! Vince  *end of comment*

2/10/2003 update: Installation of my new Indy mount was complicated by the fact that I had already drilled the firewall holes to match the old Mk 1 mount.  As with any welded assembly, the holes in the new mount were off slightly due to warpage from welding.  I had three problems to fix:  1) the top bolt tube holes were too close together due to warpage.  2)the bottom bolt tubes were warped inward about 1/16" at the firewall and were not perpendicular to the firewall like they should be.  They had to be made to fit flush with the firewall.  3) the Indy EM bolt holes didn't line up with the firewall holes.  See the pics below to see what I did to fix the problems.

Problem 1) Sorry no picture.  The top bolt tube holes were too close together.  I stuck the EM under my International 460 tractor.  Next I put a hydraulic jack on top of the top tube between the Lord mount ears.  I  raised the jack against the tractor until the top tube was straightened and the welding warpage was no more.  I went slow, raised and lowered the jack several times so I didn't over bend anything.   I could have used a press for this job but that would have required that I drive to my buddy's house.  The jack and tractor worked fine and took 1/10 the time.

Problem 2) The bottom bolt tube pads don't fit flush against the firewall.  The pads on the bolt tubes were more than thick enough to grind away the 1/16" from one edge necessary to obtain a flush fit with the firewall.  Since all four corner bolt tube pads should lie in the same plane, I set up my belt sander to grind away the excess metal.  I leveled the plane of the belt sander.  Then I used boxes, block, etc to jig the four corners of the EM  to sit perfectly level with the belt sander, sort of a poor man's surface grinder setup.  Next I turned on the belt sander and ground off the lower left bolt tube pad until it was flat on the belt.   A mirror image setup was required to grind the other lower bolt tube pad.

When done with the sanding, I used a straight edge to check that all four corners were in the same plane.  They were!  Woo hoo.... it worked.  And worked great.  When I held the EM up to the firewall the four corners were all flush and straight with the firewall... as they should be.

Problem 3) The Indy EM bolt holes didn't line up with the firewall holes.  I needed to move the existing firewall holes a bit.  Oh joy!  Moving holes isn't possible.  However, enlarging holes is possible.  After some careful measurements of the EM bolt tubes, I determined that it would be possible to use AN7 (7/16") hardware instead of the usual AN6 (3/8") hardware.  The bolt tubes on the Indy mount are MUCH thicker than those on the MK 1 mounts and my measurements showed that I would still have over 50% more wall thickness remaining after enlarging to the AN7 size compared to the Mk 1 EM wall thickness. 

Here's the wall thickness differences of the bolt tubes for those who worry about these things:
Mk1 mount: 0.500" OD, 0.375" ID, which gives approximately 0.063" wall thickness.
Indy mount: 0.625" OD, 0.375" ID, which gives approximately 0.125" wall thickness.  After drilling the tube to accept AN7 hardware, the wall thickness is approximately 0.094"

I held the EM up to the firewall and made careful guestimations of where I could "egg" out the existing firewall holes to best fit the new mount.  I hoped that if I was careful, everything would turn out perfect.  However, I was mentally prepared to remove the weldments behind the firewall and weld the holes closed if my plan didn't work.

I used the "finger breaker" shown above to egg out the firewall holes where needed.  It's a jig saw with a round file chucked in it.  The tygon tubing on the business end of the file allows you to hold it while it's running and apply pressure in the direction you want to egg the hole.  It took about one minute to file the holes.  If I'd done it by hand it would have taken me an hour.

After I guesstimated the new egg shape of the holes, I put the EM back against the firewall and used threaded rod to bolt it firmly in position.  It looked pretty good.  I had high hopes that the small amount of egg shape I'd made to each hole would be cut away when I ran the 7/16" reamer through the holes.

The shank of a 7/16" reamer is 3/8".  That is perfect for this job.  I'm no machinist, but I think it's MUCH easier to keep that reamer aligned if you pull it through the hole.  This allows the shank to keep everything aligned with the 3/8" bolt tube hole.  Use plenty of cutting oil and clean out the chips frequently.

Here's a dribble diaper I put in place to keep 99% of the mess off of my interior.

Here's the diaper after reaming.  Yuck.  All that oily stuff would have been on my floorboards.

This is the Indy mount after reaming the four corners to 7/16".   "IT WORKED!!!"  All four corners turned out perfectly round and the bolts dropped right in with hand pressure.  Also when I tightened the lower bolts they seemed to tighten perpendicular to the firewall as they should.  I was a bit concerned that they would be slightly tipped, but the reaming process ate up any misalignment that had been present.  

I still need to finish the center bolt holes.  I think I can ream one as it is.  The right side hole will probably require a new aluminum angle behind the firewall, but that shouldn't be a big deal. (Famous last words.) 

I talked to Mark about the center holes the next day.  As stated above, the holes in the aluminum pads behind the firewall were slightly egg shaped after the reaming operation.  Mark said to put JBWeld in them and re-ream to fix.  He claims that a minor egg shape of the holes is no big deal anyway.  The JBWeld will fill the hole and the nuts, bolts, and washers will hold everything together just fine.  I agree. 

WOO HOOO!  I'm not out of the dark yet, but I can see light at the end of the EM tunnel! Vince  *end of comment*

3-3-03:  Getting the gear leg and axle socket drilled.  Let's go straight to the pictures.

First we get the EM perfectly level.  I shimmed the 4 corners until the shims were level then clamped the EM down on top of them.  This should simulate the firewall for plumbness except it's rotated 90 degrees.  Make sense?

The technique that Mark shows in his manual for using a visegrip to hold the axle socket didn't seem to work very well.  I always moved the socket when I squeezed the visegrip and it didn't hold very well.  Not good when you're about to drill a hole in an $850 stick of titanium.

I had an epiphany (it happens) and decided to install a set screw.  Drill and tap for a 6-32 set screw 1/2" from the top of the axle socket.    This will hold everything FIRMLY in place on the gear leg.  IT WORKS GREAT!!!  Don't risk your expensive gear legs by using that sloppy visegrip technique.

Mark was concerned about the set screw making a scratch on the titanium, but the mark it leaves is tiny and easily polished off.  As an option you could put the set screw at the bottom end of the gear leg where scratches are no worry, although Mark claims that the bottom of the socket is more highly loaded and to avoid putting a hole there.  OTOH, it seems to me that the weakest spot of the axle/axle socket area is the four 1/4" bolts holding the wheel on, not a tiny set screw hole anywhere in the axle socket.

I used a straight length of 6061angle about 27" long instead of a board. 27" is twice the length of the board shown in the F-1 manual. This allowed me to tape a 1/16" drill bit to the top of the angle where it holds the thread away from the angle. The drill bit provides the proper angle for the plumb bob thread when the thread just touches the lower end of the angle.  Then simply tighten the set screw.  Easy.

  Then move the leg to the vee block that was waiting on the drill press and drill with lots of oil 1/8",  3/16",  1/4",  19/64", ream to 5/16".   Also easy.

This is a picture of a set of Cleveland brakes.   The brake is oriented behind the axle, not on the bottom as it appears in this picture.  The picture was taken while the EM was clamped to my workbench, 90 degrees from how it would mount on the plane.  See the picture below if this is confusing.

It took me a couple of minutes to figure out that the brake flange slid over the axle. I tried to mount it between the axle and gear leg... DOH! It looks like it will work there, but when you look closer you realize that only one pad will bite on the disc.  That wooden wedge keeps the wheel from turning while I'm mocking up the wheel pant cutouts.

Wagging a template to make the initial wheel pant cutouts.

Untrimmed Sam James wheelpants.

Making the initial cuts.  I used a jigsaw because my chain saw was out of gas.  It makes a fast but somewhat rough cut.  I'll clean that up later.

  Fear not.  This ugly thing is just a scrap aluminum to mockup the wheelpant support bracket.  The real bracket will be made from .060 4130 steel.  (I later heard that Mark is using .093 steel now.)

3-6-03:  Cutting out the wheelpant support (the starfish) and installing it between the axle and axle socket.  Nutplates to be installed at the end of each leg.

  There needs to be a bracket on the outboard side of the wheel too.  This 4130 will soon be cut and welded into a nice bracket. 

Here's the super sturdy outer wheelpant bracket.  It will have 2 nutplates installed later.  I plan to use 2 screws here instead of 1 so there will be less tendency for the wheelpant to twist. 

The crew that installed the EM to the fuselage.  FINALLY! It's on it's on gear.  Left to right:  John Crabtree, Jim Truitt, and Vince Frazier.  I can't help but notice that this project is making my hair slowly fall out.  Doh!

Gear leg fairing installation:

The hinges are positioned so that the trailing edge will close nice and snug... but not so tight that you can't get the pins in.  I can't say exactly how to do this... just use your MK 1 eyeball and give it a go.   Just like on the cowl hinge, you can use an exacto knife to clean out the uncured JB Weld that glues the hinge to the fiberglass.  The rivets, well, I consider them secondary to the JB.  BTW, use dead soft rivets in fiberglass.

Well, lookee there.  They seem to fit.  As you can see in the second picture, the hinge pins (2 per side) are installed from the middle.  The bottom trailing edge has a notch cut out of it just to access the pins.  I'll either make a little cover for it, ignore it, or maybe just put a piece of tape over it.  I haven't decided yet, but a small cover seems likely.... aw heck, a piece of tape will do just fine.

Tape over everything and then apply a coat of PVA mold release.

  Mark's intersection fairings looked fine on the outside, but the inside didn't fit around the cowl very well.  This was my fault because I fitted my cowl up tight against the belly. 

Smear on the clay. Actually this is some stuff I borrowed from the art department.  It's call Schmitt wax because calling it sh*t wax doesn't sound very polite.  It's made from axle grease, sand, microcrystalline wax, and who knows what else.  But it works very well.

The key to getting a smooth mold is to use a 2" chunk of hacksaw blade as a scraper to knock down the high spots.

Ready for fiberglass..... yuck.  Can you believe some people actually build the entire airplane out of that sticky, nasty crap?   I skipped the pictures of laying up the fiberglass.  Why?  Well, I didn't want to get resin on my camera!  And because I get impatient when doing fiberglass....grrrrrr.

Here's a shot with the sand bags taken out of the fuselage.  FWIW, the fuselage weighs about 200 pounds empty.  The fairings gap just a little on the trailing edge when the gear legs flex inward, but that is expected.  And since I haven't made any sort of fastener for the trailing edge yet, I'll remedy that minor problem during the finishing and painting.  

Jim Stone's HRII

  Eric Hansen's gear leg fairing fluttered and tore itself up.  Eric had bonded the trailing edge together.   Eric mentioned that he hadn't put any of the Great Stuff non-expanding foam at the top and bottom as required. 

Jim Cash did his glf's this way:  Tom and Guys, I promise not to repeat this again. If you will install the gear leg fairings using an aluminum hinge at the back, running the full length of the faring, and use either non expandable or low expandable foam sprayed as far down as possible on both ends of the fairing (probably a 6'' long layer) they won't come off. I take the black airplane out to over 250 indicated on just about every flight (4 to 5 Gs are routine) and the foam has never even broken loose. Its just my opinion, but with over 100 hours with this installation (and I fly an airplane aggressively---Lui can attest to that) I think the product is OK if installed this way. The aluminum strips on both sides provides a little more rigidity, and the foam seems to hold the whole thing in place very well. If you want more detail email me offline at jcash@centurytel.net.   Jim Cash  *end of comment*

Today I lost my left gear leg fairing (GLF) to flutter. I was at 220 KIAS, 1 G flight, in a slight dive when I felt a buzz in the airframe that lasted  about 1.5 seconds, felt the airplane yaw slightly, then smooth again. I new something had just fluttered and departed the plane, I did not know what but suspected a GLF or wheel pant. Sure enough when I landed the fairing was 80% gone, and a good chunk of the wheel pant intersection fairing also. This will require a complete rebuild of the fairings and wheel pants on that side. It just exploded off of there. Luckily there was no other damage, and the landing was uneventful. I am very happy that is all it was, but very unhappy I will be gluing, sanding and painting again.

I had previously tested out to 250KIAS and 4 G, and routinely operate above 220-230 KIAS so I thought I was safe from the flutter demon. My preliminary thoughts are that with flight time and landings, the fairing has been getting looser and looser and the original expanding foam had completely let go of its holding power some time ago. I think my original tests were done when the expanding foam was still holding, so everything was solid. The right GLF can be moved slightly in rotation about the gear leg and I think this is what set up the left one to flutter. I don't recall one GLF being looser than the other, but it probably doesn't take much.

So for those flying and still building, no free play in rotation for the gear leg fairing seems like a good idea. What I plan on doing different to prevent this from re-occurring is to glue foam rubber weather stripping inside the fairings to press against the gear leg fairing. This will insure a tight fit of the intersection fairings and the GLF and damp any motion before it can get started yet still allow the required motion between the parts required for gear leg flexure. Once the expanding foam gets too loose and your intersection fairings loosen up, problems can occur. I just turned 80 hours a couple flights ago and was starting to think I had a pretty reliable airplane.  Greg Nelson N144X *end of comment*
 

I am happy with my glass fairings. Yes I did crack the ones on my HRII but it was a bad landing, and I am sure that the metal fairings, even with the split, might have shown some damage. I was able to remove the fairings, glass over the crack and repaint them, good as new.

The key to these things, in my opinion, is to use the hinge method of attachment and foam top and bottom. Before you install them, line the top and bottom of the faring with packing tape. This way if you ever have to take them off the foam will stay with the gear leg and you can easily remove the faring. This will mean that your "repaired" fairing will still fit the upper and lower gear leg intersection fairings. They might not if you had to add new foam.

I have about 600 hours in three different rockets and I only have had one small problem with the fairings. The metal fairings on my RV4 were showing wear at 300 hours and many that you see at airshow look pretty crappy after a few hundred hours.

Gear leg stiffeners:

I did like the basswood stiffeners and I am thinking of adding them to my HRII. I think that they are a must, even with the Indy Mount. They are simply one half inch thick boards about two and a half inches wide. I glued them on, front and back, with ProSeal and then wrapped the leg in four locations with glass to secure the whole mess. Glass over the entire leg will crack and might let the stiffeners work loose.

Install the dampeners with as little weight as possible on the gear legs. Install the gear fairings and upper and lower gear fairings with the plane loaded to simulate at least full fuel and pilot.  Tom  *end of comment*

Changing Gear leg sockets:

We made a jig to allow fitting of new axle flanges to existing holes.  Aluminum square tubing clamped to the brake disks allowed measurements against a centerline and each other. Blue skies   Bob Wahl

I highly advise that the final hole size should be reamed with a hand-reamer .001-.002 under-size even if you don't use a taper-pin. There are too many variables with drilling to final size with a hand drill.  Bob Japundza  *end of comment*

Miscellaneous:

Q: Speaking of toe-in toe-out. How is it measured. 1/16 of an inch means what? 

A: (This refers to HRII gear legs) Are you going to drill the gear legs with the engine mount on the fuse?? IMHO, a bit out of sequence, but possible. I set mine up with 1/8" (1/16" each side), and it wasn't quite enough. I'd say 3/16" might be closer to optimal.

The following few paragraphs talk about a problem that some of the F-1's have been having.  The gear legs get slightly loose in the gear leg socket.  Although annoying, these problems are not unexpected (as with anything new) and will be overcome with a little elbow grease!  Aw heck, my Harmon flying buddies have had gear problems also.  It's the Achilles heel of the Rockets! Vince

It would be nice if we could get the Czech engineers to respond to this issue as it really is something that is out of my area of experience. Perhaps Wess Triff could comment on my speculations. This puzzle will be solved.   Tom Martin

When I mounted the legs on the engine mount I noticed I could check the nuts once a week and I could turn it about 1/8" every time. It finally got to a point when it stop turning. Then I had the need to remove one of the legs.   Guess what? It is a mother to remove. It appears, once it is there, it really wants to stay there. I hope I don't ever have to take those out.   

At the beginning stages of fitting the gear legs I also removed the powder coating that I believed was in the way. I also found some welding residue on the inside of the socket that needed to be smooth out. These were not allowing the gear leg to go all the way in. I could put the nut but I knew it needed a bit more thread as Tom mentioned here. Once those rough spots were taken care, I could get more thread to show up. It now appears to be all the way in.   Luis 21 *end of comment*

Engine Mount update 5-20-02  Hi Fellas:  Well, we have the results of the analyzing of the Engine mount and gear leg assembly. This testing showed some surprising results, to say the least. I will make the appropriate changes to the manual.
In the meantime, please note the results and clean all debris and grease from the lower socket area as noted. We will come up with the proper reaming tool as quickly as practical, and distribute this tool (or tools) among the flying ships first, and then to the ships which are closest to flying, and then to the remainder of you builders.   Cheers!
Mark

This letter from Petr was attached:

Hello Mark,
HPAI ordered in Aeronautical Research and Test Institute an analyze of possible reasons for cracks creation in F1 engine mount. Here are
results of this analyze and some possible solution recommendations:
1) The main reason for cracks creation in upper area of main leg holder in F1 EM is a shimmy effect of leg during taxing. The cracks have two cross direction which show us that the leg is loaded by torque and this torque was supported only in upper area of EM by slot and nut.

HPAI note: All notes about nut loosing and problems with their fixing support this idea.

Tom Martin gusseted his EM like this.  I don't have any details yet other than these pics.  Mark says the gussets are .063 4130 steel.  *end of comment*

Here's some more EM modification pics from Lui  *end of comment*

  I finished reaming the gear leg sockets which was not much of a job because I was able to bolt the mount to a sturdy table. I suggest that everyone check the amount the gear leg threaded portion that extends above the top of the mount to make sure that the leg is bearing on the taper and not the bottom of the slot in the mount.

To new builders: IMHO a sturdy bench such as the one in the photo is essential. Mine has a top that is 4' X 5'6" X 35" high and has a bottom shelf which when loaded up with all your junk keeps the table in place. Use 3/4" particle board and you can screw building templates, bending jigs etc. to it to aid in the building process.

Blue skies,  Bob W  *end of comment*

Hi Fellas:

If you want to modify your EM before reaming, go to the manual update page & see how it was done on Tom Martins' mount.  The CZ engineer (Petr Varadi) had a look, & agreed that if you wanted to do something, this would likely be a good method. 

If you have already run the reamer in the sockets, then about all you have available as an option is to weld the small gusset at the lower bolt attach tubes.  As this showed up as the highest strain point (in a hard landing), you will get a large benefit from this small mod.  No subsequent reaming will be need after this small gusset is welded onto the mount.

We are assembling an F1 here in the shop.  It will be run with a non-modified mount first to see how long that may last.  The field here is ROUGH, so any faults will show up rather quickly.  After that mount shows distress, we'll make repairs (likely to the Martin/Frederick Mk.1 Mod1 status), and see how long THAT lasts. If that one breaks, we'll change to the Mk.2 EM.  Sound like a plan to you?

FYI: my Harmon mount went 700 hrs on such a strip, and the F1 mount is considerably stronger. The cracks to the HR mount mimicked the F1 stress damage exactly. I had it rewelded without adding any gussets, though it looks like the M/F Mk.1 Mod1 would have worked there too.

Procedure (after all welding is complete):

ream socket with reamer (use plenty of cutting oil; turn the reamer with a 1" wrench)

stop reaming when sufficient contact is achieved, or 11/16" of thread protrudes from the top of the socket

clean socket & leg thoroughly

re-assemble leg to socket; tighten leg nut to 40 lbs/ft. Safety wire nut.

Cheers!  Mark  *end of comment*

9-12-02: I have been getting some good flight time in on the F-1 in the last few weeks, and it is really flying nice. I now have just over 60 hours flight time. This plane is an absolute blast to fly.

My crows foot for the upper gear leg nuts arrived from Snap On, so I pulled the cowling to check on firewall forward goodies and of course the gear leg nuts. This crows foot should be standard equipment if you own an F-1. Let me repeat that, If you own an F-1 Rocket, put a crows foot for the nuts in your tool box, you will need it for routine maintenance of the gear legs, reamed or not. There is just no way you are going to be able to check and tighten those nuts in service once the engine is installed and plumbed with out the crows foot. This is important! You can only do so much with channel lock pliers.

I put the crows foot on the nuts and checked the torque. Both were low, but not loose, this after 10 hours from the last time they were checked and tightened. The inspection lacquer was not broken, it is the gear moving up into the sockets. I was able to get another flat on the right nut, and almost three flats or half a turn on the left! I found that I could torque the nuts to 40 Foot/Lbs, then rock the ship back and forth with the wings, and for and aft against wheel chocks then check the torque again and it would be low, just like that. I kept doing that until the torque stopped changing. This was the first time I have been able to do that since I just now got the crows foot. I wish I had it all along. My gear is still working its way into the sockets. I have two threads showing above the nut on the left and 2.5 threads showing on the right. Eventually they will stop moving, but I'm not there yet. An inspection with flashlight and mirror showed no signs of any distress on the engine mount, so good news there. Looks as good as the day it was installed. Just wanted to update everyone on the gear leg status of my ship.    Greg Nelson F-1 #8   *end of comment*

Mk II Engine Mount 1-15-03  The Czech crew has a Mk 2 mount in production now to hopefully cure some of the concerns about broken EMs.  Here's a few pics:

Mk II Engine Mount 6-1-03    If you have a Mk.2 EM, we are requiring that it be converted into a Mk.2 Mod.1 version with the kit supplied by Team Rocket. See the attached photo for an example of the finished product.   We will supply 2 sleeves and 12" of 3/4"x.049 4130 tubing in the kit. The welding is pretty easy -- the local shop had no problem with the instructions.   Cheers, Mark

Jim Cash had this to say about the new mount: 

Hey guys,

I thought the engine mount problem would create a lot of discussion, when word got out about the Indy mount. I have been weighing this for a month now, and would like to share my thoughts and reasoning with you.

Since my airplane was the first, I was pushing Mark hard, early on for a mount. The lack of one held me up for a couple of months, as matter of fact. That was the last part needed to complete my project. As a result, I came up with one of three bastard mounts that are similar to your production Mark l mount, but somewhat different. Several of us have up to a couple hundred hours on these mounts, and one has broken twice. None have collapsed causing major damage.

I immediately ordered an Indy mount after hearing about them, mainly because mine is different and could be harder to duplicate later as memory loss occurs. I don't intend to replace my existing mount right away. Instead, I want the Indy stashed in a corner if I need it. I may install it sometimes in the future during a hard cold winter.

Since word got around that I had ordered a new mount, I have received several inquires from builders trying to decide if they should order one. After a lot of thought, here is my answer and the reasons for it. The Indy mount is going to be available for the foreseeable future. If your kit has one of the new Mark ll Czech mounts, I would definitely not replace that one. That could prove to be an excellent compromise. If you have the Mark l, and are at the point in the building process where it is easy to install, I would definitely order the Indy mount. If you are like me with a finished airplane, the installation process is going to be pretty extensive. I am going to torque the nuts every time I remove the cowling, watch for cracks, and probably wait to install the new one when I need it. If I had the regular production run Mark l mount, I would not have ordered the Indy until it was needed.

There is no doubt that the strength of construction increases from Mark l---Mark ll---Indy. However, this is one of these areas where it is easy to overkill. So far, out of three breaks the F-1 has experienced, there has yet be any firewall damage or gear collapse, which speaks well of even the Mark l mount. It is too early to be sure which will prove to be best over the long term. Sometimes, no action is the right action. I have an engineering background also, and I can assure you that it is possible to overbuild a mount to the point where you start transferring stress from stronger point to weaker---finally to the firewall itself. When that happens your problems grow rapidly. I just finished helping a friend replace a firewall in a Piper Pacer, and that was interesting. Someone else made the point that this problem is not unique to the F-1. That's very true. Van and John Harmon have had similar problems. Art Chard was Van's first employee, built most of the RV prototypes, and he has many stories. Another thought that keeps reoccurring to me is that one person's definition of a good landing can be different than others.

Hope this helps a little. By the way, $800 is an excellent price for an engine mount of this type. Note Mark is passing them on to us at his cost, which is a great help. I personally did not expect him to take my old mount on any kind of exchange, because right now there is nothing wrong with it. These things take such a beating, that I kindly put them in the category as replaceable items anyway. I guess (at least in my case) I am buying $800 worth of "piece of mind".

Jim Cash, #10  *end of comment*