Hooptee pitch gauge.

Has anyone got the original magazine article from MA for this? I have the scan from the AMA archive, and there is a web site that has it. I don't know what to scale the gauge to, the web site says it should be 1" center to center on the letters, but that can't be right, this would make the overall dimensions approx. 13", and the plans call for a 10" overall dimension. This would not have fit on the magazine page either, so it can't be right. I can guess roughly what it shoud be, but if someone could measure center to center on the letters that would help.

That would be August 1975 page 35.

Thanks

I recently built two of these and ran into the same problem you did with the web site.. Don't remember the URL.. I acquired the magazine and reproduced the article with a better image of the scale.. It's posted on the Tulsa site..

http://www.tulsacl.com/WorkShopFly.html

>Has anyone got the original magazine article from MA for
>this? I have the scan from the AMA archive, and there is a
>web site that has it. I don't know what to scale the gauge
>to, the web site says it should be 1" center to center on
>the letters, but that can't be right, this would make the
>overall dimensions approx. 13", and the plans call for a 10"
>overall dimension. This would not have fit on the magazine
>page either, so it can't be right. I can guess roughly what
>it shoud be, but if someone could measure center to center
>on the letters that would help.
>
>That would be August 1975 page 35.
>
>Thanks

I just measured the one I built from the magazine article years ago and the distance between the lettered lines varies between 0.68 and 0.72. The four divisions from A to E each measure 0.71, as do F to G and I to J. E to F is close to 0.72, G to H is 0.70, H to I is close to 0.73 and J to K is 0.68. The distance between A and K measures 7.09.

As I recall there are other inaccuracies, which is why I got disappointing results the first and only time I used it. My conclusion at the time was that the only way to solve the problem was to make totally new (and accurate) artwork. At the time I was not interested in such an undertaking and have not touched the gauge in all these years until now.

I built one from photocopies that someone sent me. Jim Hoffman, I think. I'm not at all sure how accurate it is. But it provides internal accuracy. I've used it for years and the props may 4.45 when the gauge says there 4.5, but I've used it so long that I have a pretty good idea of what's what. In the end, I think that's all that matters.

Thanks for all the replies.

Randy, I think we are on the same page on this. While it may not be 100% accurate, if built well the results should be repeatable.

Bob Reeves, the link didn't work for me, but I'll try it again later. I'm sure I've seen your sight before. When I stumbled across the other sight, I thought it was the same one. But it is a CL racing sight, that's where I got the information on the 1" spacing.

I was able to go to the MA archive and download the original article, but then printing it to original scale is another story. If there were only one known reference on it I would be ok.

I have a 10 month old son, so my project time is very limited right now, so instead I'm doing small projects that will hopefully make overall improvements in everything from building to flying. So instead of trying to tackle a new plane right now, I'm building jigs and accesories, like the hooptee, lots of different sanding blocks, incidence meter, etc. etc.

Speaking of my 10 month old, I just learned something new from him. If you are still typing your message here, and you hit the escape key, everything you typed is gone.

Austin, Just tried and the link worked, not sure why it didn't for you

When you are able to get to the Tulsa site Scroll down and you will see the pitch gauge downloads right after the speed chart. I spent allot of time cleaning up the scan, making sure it was as accurate as possible and sizing the image so it would print the correct size on letter paper using most graphics programs. The instructions are with the links to the downloads.

I use mine quite a bit and find it to be as accurate as the stated pitch on most APC props. The CF props I ordered also checked to be as advertised so I would say it is close enough for government work..

>
>I was able to go to the MA archive and download the original
>article, but then printing it to original scale is another
>story. If there were only one known reference on it I would
>be ok.
>

I just pulled my copy of the August 1975 Model Aviation and did some measuring. It seems the xerographic copy I made of the scale years ago for my gauge introduced distortion that went unnoticed until just now. The distance from the tic mark under A to to the tic mark under K measures exactly 7.00 inches in the magazine. My xerographic copy measures 7.09 inches.

Yep, worked that time, thanks once again to everyone.

>Yep, worked that time, thanks once again to everyone.

One of the problem with pure analog products is the propensity for distortion every time a copy is made. The problem continues to compound itself as copies are made of copies, etc.

Before John Kilsdonk passed away, he gave his full permission for me to copy the Hooptee into CAD. I enlarged the bottom plate to handle up to 14" props, and committed to CAD the template that indicates pitch. Actually, I made up two. One measures just degrees and I use a conversion chart. This is more accurate, but less user friendly. The other I made up a chart similar to John's original. The differences are that the diameter indicators no longer correspond to a letter, but instead to a number, and that number corresponds to the diameter that the pitch is being at. The other is that it goes up 14" diameter. I then exported to a .pdf file so that I (or anyone) could print it out without a CAD program.

I have only used the degree plate, but both are made up. I should verify the Hooptee style plate for accuracy.

If there is sufficient interest, I will clean these up a little and make the .pdf - or the .dxf/.dwg for that matter - available to anyone who want to take a look at it. There is nothing fancy here, just a simple guage that will give consistent results and that I know had not been distorted by the copy of a copy of a copy phenomena.

I'd be interested.

I'd be interested a PDF file would be great.

I'd be interested in a dxf file

>If there is sufficient interest, I will clean these up a
>little and make the .pdf - or the .dxf/.dwg for that matter
>- available to anyone who want to take a look at it. There
>is nothing fancy here, just a simple guage that will give
>consistent results and that I know had not been distorted by
>the copy of a copy of a copy phenomena.
>
>v/r - Bob Kruger

I am definitely interested and would love to see it. I particularly like the idea where you got rid of the letters in favor of the actual diameter. Of course I like the idea that it will be accurate also.

BTW, I did a few spot checks of the Hooptee scale in the magazine and got the following accuracies:
At a diameter of 6 inches and 3 inch pitch the scale indicated a pitch of 2.92. Similarly, an 8 X 4 was 3.88, 10 X 5 was 4.82, and 12 X 6 was 5.77.

Bob,

I would like to have the CAD file, would like to create an accurate replacement scale for those that built the unit as it was published.

If you would like I can probably talk Catdaddy into uploading it to the Tulsa site as an addendum to the original article with proper credit of course.

>Bob,
>
>I would like to have the CAD file, would like to create an
>accurate replacement scale for those that built the unit as
>it was published.
>
>If you would like I can probably talk Catdaddy into
>uploading it to the Tulsa site as an addendum to the
>original article with proper credit of course.

OK, can do.

It will be a busy week. I want to clean up the drawings a little bit and make sure that they are right.

Nice thing about a .pdf is that if there are any innaccuracies introduced, they will at best be "first generation" , e.g. the calibration of the local printer or whatnot. Much better than "a copy of a copy of a copy..."

Bob,

I'd definately be interested. Can you start a files section on SSW?

>Bob,
>
>I'd definately be interested. Can you start a files section
>on SSW?
>

Don't know about a files section, but I can certainly put the file on the server and give out the hyperlink to get it.

Bob,

That would be great.

I have the issue. In fact, I sent it to someone here, and he made his own copy, to insure accuracy.

Can do likewise for anyone interested. Just send the mag back when you are done. Currell

It was me the results went on the Tulsa club site. The image on the site is better than a copy from the magazine as it has been touched up to eliminate a few inaccuracies that were in the original print. Thanks for the loan of the magazine...

This looks remarkably similar to the Prather pitch gage. Has anyone inquired about the availability of these. With enough interest, another production run could be made.

>This looks remarkably similar to the Prather pitch gage.
>Has anyone inquired about the availability of these. With
>enough interest, another production run could be made.

Not according to the Prather family.

While I may well not be current on the subject, it is my understanding that Richard Oliver (RO-Jett) is finalizing his new pitch gauge and that it will come fully big-prop capable, which is not the case with the Prather gauge even if you do find one.

I've put off doing anything at all until one way or the other Richard decides what he is going to do. I truly need a new pitch gauge, but little out there seems a step up from what I used to have.