Blister on 53'

[trials20]

Hello to all.

First, I have to say the amount of information on this site has been outstanding for my 53' rebuild, searching the forum has always answered any questions.
But I do have a question on what was on the back of my plane when it was still US registered.
What looks like a solid dome in a tear dropped shape between the tail and start of cabin area, it's not on the plane now but I do have a large patch of the similar shape in its place.
Anybody know what it might of been?
Can't find any info on the interweb but somebody here maybe seen one around.
Again, thanks to all who make this site my daily read.

By the why, it will have a shiny coat of RED paint soon.

us reg.jpg

[Ryan Smith]

I'm interested to know as well. I've seen quite a few fastback 172s out there with that same "bump", although I've only seen them painted white, or what appeared to be their natural black color.

Could it perhaps be some sort of old VHF comm antenna?

[GAHorn]

It is an older style ADF sense antenna.

[c170b53]

And likely to have a fair amount of corrosion underneath the patch, hopefully your machine has been spared.

[trials20]

Thanks gahorn for that info.
Researched that stye of antenna and found examples of that installation on other planes. I have left over brackets in the tail section which would of held whatever radios for that time.
Patch was removed and cleaned/primed as well as the complete airframe stripped, hoping this spring for some more airtime.

[DaveF]

It is an older style ADF sense antenna.

Just to be an irritating nitpicker ... it's the loop antenna. The sense is the long wire.

I had a motorized loop antenna on the Lear T12D ADF in my Cherokee a long time ago. It was fun to watch in operation. The motor rotated the loop to keep the signal null pointing to the station, quite a lot of the time!

LearLoopAntenna.JPG

[c170b53]

Just looked at your s/n....it's 6 planes newer than mine, I had the same patch but chose to replace the entire skin. Also interesting that you're in Victoria and I'm in Vancouver. There's another at YYJ, I think we should rendezvous YCD if possible in the spring or when your ready.
Humm..Victoria.. Trails20 have you ever thought of going to a convention ?

[GAHorn]

It is an older style ADF sense antenna.

Just to be an irritating nitpicker ... it's the loop antenna. The sense is the long wire....

That's exactly correct. It was a test to see if anyone was really paying attention.

On a side-thought, ... I am slightly perplexed some previous owner, presumably to improve performance, spent (lots of) money on drooped leading edges but was seemingly unbothered or unwilling to spend a much smaller amount to remove drag from that old antenna.
When looking to improve efficiency on "experienced" airplanes, one of the simplest and cheapest things one can do is consider the existing antennas. Get rid of unused or obsolete ones(which are also corrosion-magnets) and look for out-of-rig and unnecessary drag in the form of sloppy rigging (such as out-in-the-wind brake lines and unnecessary external equipment.)

[170C]

Good points George or to speed things up they could just paint their plane GREEN

[daedaluscan]

Just looked at your s/n....it's 6 planes newer than mine, I had the same patch but chose to replace the entire skin. Also interesting that you're in Victoria and I'm in Vancouver. There's another at YYJ, I think we should rendezvous YCD if possible in the spring or when your ready.
Humm..Victoria.. Trails20 have you ever thought of going to a convention ?

I own one in Victoria, and I know of at least two others there. I know the owner of one of them.

I would enjoy meeting other 170 owners and a 170 convention is definitely on my list, but next years is quite a hike from here and I have limited time.

A BC meet would be fun.

[trials20]

Your right, a BC meet would be be great. I'll be based out of YCD when she comes all together.
A convention is on my bucket list but a Canadian tour has top billing.
The picture that shows blister is when the plane was still US registered before 1980.
The dome was removed years ago.

[jlwild]

From the above comments about 170 Conventions, it sounds like there are enough Canadians interested to hold one in BC again. The 2006 convention in Kelowna, BC was awesome.