The International Cessna^® 170 Association

Hi Folks,
I joined the association a few weeks ago after browsing thru the forums for quite a while.
I bought a '56 172 last year that had been sitting in a field for twenty years. I planned to restore it and decided a while back to convert it so I figure I belong here rather than the other cessna groups.
I would like to know if any of the guys who have done the Fravel conversion would have a picture of the form blocks they made to build the tailwheel bracket ? I have a few ideas but I don't want to reinvent the wheel.
Ive seen 53B's pictures and he did a beautiful job, maybe Mark will have some input for me.
I've got most of the parts gathered and soon as we're out of this minus 30
weather and my garage heater can keep up I'll get started.
Any and all advice will be appreciated.
Thanks...........................

Jimmy M
Welcome and I see you are informed partially, by perusing the Forum. There is much information here to help. Wish you good luck on restoration.

John

Hi, Jim! WELCOME!
Sorry to say, I'm not very familiar with the Fravel conversion. Several of the Bolen conversions belong to TIC170A, and you might get some pointers from them, as I'm sure they'll notice your msg.
Again...Glad you're with us!
George

Hello Jim!

Glad you're here!!!
I've got a '56 172 (29015) with a Bolens Conversion and I absolutely love it! It flies straight as an arrow hands off, and tracks on the ground the same way. I was going to convert a 172, but then this plane popped up in TAP and I took it.
You have to let us know... when you get into the bulkhead to mount your landing gear, are there holes already there like a '55 170??? !
Good luck and keep us posted on your progress.

Joe

Yes Joe the holes are already there, all we do is add a few more bulkhead stiffeners and we should be good to go.
I'm wanting to do the tail end first as it's way more difficult ( by the time I'm done my bad language should be ready for golf season )

Welcome :
I am also doing the Fravel Conv. The main gear boxes are more difficult than you know. There is a angle stiffner across the floor thru the flap handle tunnel that is alot of work installing. I have my tailwheel pieces cut but not made to conform with the fuselage what a pain. Been trying to find an English wheel but no success. The tail pieces ended up similar to Marks so that the tailwheel support has a place for the through bolts. Are you doing any other mods ? Good luck Tweener

Jim,

The tail is more difficult???
That would seem like a piece of cake!!! I don't have a site where I can post pictures, but I'll get down the hangar Saturday and snap a few off of my tail bracket and PM them to you. I also see an added stringer on each side for more 'beef'.

Joe

Thanks for the warm welcome guys.
I think the tail will be more difficult for me because I have to shape that .080 material.
I have the stripped fuselage in my garage and I'm thinking the front end will be easier ( no piece of cake tho ), that stiffener angle is going to be a challenge for sure.
I don't know if an english wheel will be strong enough to shape the tail parts??
Down the road I'm hoping to go 180 Lyc. and floats, but then my other plane will have to go. ( I don't know if the wife will see me needing two airplanes )
Joe ....pics would be great, a guy can always use some fresh ideas. Up here in Canada we can wander a little from the STC.( altho very little )
Tweener.............I've also got Mark's pictures, didn't he do a beautiful job ??
See ya.....................

Mark did a nice job and told me he hammer formed the piece on a oak form. I have been told by a couple sheet metal guys a Engish wheel will work .080 now just need to find the wheel. Alan Quackenbush in Ca. did this conv. several years ago and also hammer shaped his parts. Might be I'll end up with a hammer in my hand. Mark removed enough skin to slide the angle in the front. Alan cut a 2 inch hole and slide his into the front and patched the hole. Be glad when it warms up so I can get after this project.

hi jimmy
i agree.
keep us all up to date on your conversion process.
lots of pictures!!
also, tell us about your aeronica homebuilt!
i'm considering building a
wag-aero L-4 grasshopper!
dave
'iowa'

Hi Jimmy,

Sorry for the late response. Welcome to the 170 Association! I didn't get many pictures of the fabrication of the tail wheel brackets or the tooling. Honestly I didn't think what I was doing was going to work. I've been writing down the steps that I took and I have to dig the tooling out of the hangar to get some pictures. I should have this info available this weekend.

The "engineering" of the fabrication for the tailwheel parts is is tough. The actual installation of the parts on the airplane is very easy. Installing the gearboxes was three times as hard as thought it would be. Keep in mind that I was doing this to an in service airplane with the wings still on it, not a project.

I was looking for a better way to form the brackets rather than just using a hammer. I looked into the english wheel, using 2024-0 then heat treating to 2024-T3 and I even tried to use the stock 170 bracket. During all of this looking, I just decided to make a form and see how easily the metal would bend around it. I was worried about work hardening the parts and making them prone to cracking. This still may be a problem down the road but time will tell. I used the biggest deadblow mallet my Snap-on guy had and after designing and building the form and cutting out the parts, I was able to form them in about an hour. I'll get you more details and pictures this weekend.

I'm very pleased with the outcome of my conversion and appreciate everyones positive comments and interest!

A friend of mine and I converted his 1956 C172 to a tail dragger using the Fravel conversion. We thought building the tail wheel fittings was the hardest part. That said we found the dimensions for the .080 tail wheel brackets and doublers did not have sufficient edge distance. We made them a little wider to have the correct edge distance. We made a fiberglass glass mold of the aft fuselage then pored a cement buck to hammer form the fittings. We used 2024T0 and then heat treated. The location of the fittings on the rounded bottom sides of the fuselage complicates things. The results were good but time consuming. You may be able to form in T3 but it will take a while. I will check but I do not think he still has the form. The aircraft looks good and handles great.

Icranton,

I saw your posts of a few years ago when I started my conversion. I was wondering if you remember the expense incurred to heat treat the parts. Not only could I not find the 2024-0 in the required thickness, the heat treating was going to cost about $1200.00.
You are correct about the dimensions. I was prompted to investigate that deeper from your previous post as well. They did not allow proper edge distance for the 3/16 bolts.
I would like to make some spare brackets if I could get it done inexpensively.

Thanks for the insight.

Well, I just came in from the shop where I made up a mold for the tailwheel bracket out of heavy wall pipe with a metal plate welded to it at one end.I supported it in a big vise and made up a dummy bracket out of .060 soft. It came out nice.
I put the .080 2024 in and started with the hammer. I had it just about right, gave it a few more taps and it SPLIT, right in in that tight little corner.
I promptly reverted to my very best golf language, and gave up for the day.
I'm thinking of doing this in 4130 soon as I can figure out the thickness.
.060 or maybe even.050. I'm worried about that 2024 cracking now.
I'll for sure wait for Mark's pictures of his tooling.

When I get a few minutes I'll tell you about my homebuilt Aeronca Super Chief ( I'll put it the pilot"s lounge ?? )

When forming the tail piece, be very sure the material being formed is completely annealed to preclude the breaking problem outlined above.

In the annealed (soft) state, 2024 is generally very malleable.

If you ues 4130, will you be in compliance with the STC?

It would be a real bummer to form it and get it installed and then have it rejected by the inspection authority for non compliance with the STC.