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Re: Rigging Floats on the Highlander

PostPosted: Mon Jan 25, 2016 7:05 am
by Jack L
Thanks Pete,

Two friends have just completed rigging their Highlanders and one set the step 1" Aft of the most rear CG while the other set his at 4" Aft. Both installed amphibious floats and will have to wait until spring for test flight. The position of the step of the three Highlanders (including yours) on Zenair amphibious is from 13" to 19".

I have straight floats and will wait until the snow melts for rigging and will decide where to set the step at that time. I am leaning towards going aft of CG but not by much since my aircraft empty CG is currently below 8.9".

Jack

Re: Rigging Floats on the Highlander

PostPosted: Mon Jan 25, 2016 7:57 am
by av8rps
Thanks for the info. Wow! A reversing prop on a Highlander floatplane...I have got to look into that!!!!

Re: Rigging Floats on the Highlander

PostPosted: Mon Jan 25, 2016 6:46 pm
by pt17
Hi Jack, it will be interesting to see how that CofG works out. The Zenair recommendation was 2" infront of the most aft CofG, and fully loaded my CofG is exactly in the middle of the envelope. It does move fwd as fuel is used, however not much due to the CofG position of fuel. If I did not have the Airmaster prop, and battery on the firewall, I would have quite an AFT CofG. To place the step 4" aft of the most AFT position, I think might limit the ability to load the airplane to max wt. I will watch with interest.

Re: Rigging Floats on the Highlander

PostPosted: Mon Jan 25, 2016 7:41 pm
by Jack L
Hi Pete,

The following is from the Zenair site:

A Word About Rigging your Zenair Floats:


If installing the floats on an aircraft design for which the aircraft designer/manufacturer offers rigging instructions, follow those instructions! If designing your own rigging, here are a few more "rules of thumb" and suggestions from aircraft designer Chris Heintz:

Step position: Floats should be rigged so that the step will be located approximately 2-4 inches behind the "most used" CG position.


I watched your take-off video numerous times and it appears as if the aircraft is performing well with your set-up. One thing I did notice is the rear of your floats do not sit as low as C-IBAD did when it was on floats and his step is positioned aft of 15". Ironically when Bob Dimond, the guy who set his at 4" aft of the most rearward CG called Zenair they told him that it was permissible to go 2-6 " aft of the most used CG so with this information he is in the numbers. His aircraft empty CG was 10.4 and now on floats it is at 10.7.

Like you am very interested to see how all the different combinations will work. My plan is to try to position the float center of balance as close as I can to my aircraft C of G as and perhaps a little aft as I am nose heavy to begin with.

What is your MTOW on floats in Australia? We are currently allowed 1430 lbs in Canada but I will be asking for an increase to 1550 lbs. Bob Dimond's aircraft now weighs 971 lbs with the amphibs so with him, full fuel and 88 lbs of baggage he is maxed out and within his CG limit.

I am sure that there will be more to come on this topic.

Jack

Re: Rigging Floats on the Highlander

PostPosted: Tue Jan 26, 2016 7:07 pm
by pt17
Hi Jack, I don't recall seeing that info from Zenair, however it was 3 years ago when I was setting up the configuration. It is interesting that it says the "most used" CofG position rather that the "most aft" position. It does seem however that the position is not super critical. I am using the 1430lb limit as well, and my aircraft is 3lb heavier than your friends. Because most Highlanders seem to be nose heavy, I think any Step Position close to Aft CofG will work fine.

Re: Rigging Floats on the Highlander

PostPosted: Tue Jan 26, 2016 8:15 pm
by Jack L
Pete,

I agree that the position does not appear to be super critical. If you consider that the position of the seats vary from 12 to 18 inches for a difference of 6 inches it is the same difference that you and Bob have between your floats. Bob will be limited to 88 lbs in the baggage area if he is solo with full fuel while you can exceed that limit as your CG is more fwd. We all have to manage our weight and balance.

I would love to see some pictures of your back country destinations in Australia if you have them.

Jack

Re: Rigging Floats on the Highlander

PostPosted: Thu Jan 28, 2016 6:04 am
by pt17
Jack,these floats sure are fun! Videos of Amphib takeoff and Landing https://youtu.be/GwOq3BZIw-Q https://youtu.be/lyusb51tOUU I will be keen to hear how you go with your straight floats.
Image

Re: Rigging Floats on the Highlander

PostPosted: Fri Jan 29, 2016 1:59 pm
by av8rps
Pete,

Love your videos. That is a very nice looking, and performing Highlander.

So now that you are getting some more time in your plane, could you be so kind to provide us with some performance specs (like speeds and climb rates, empty weight, etc.). I am really curious how that prop and engine combination performs on a Highlander amphib with a 912.

Paul

Re: Rigging Floats on the Highlander

PostPosted: Thu Feb 09, 2017 8:39 pm
by pt17
pt17 wrote:Hi Jack, I only just found your question, as I only visit the web site now and then. To answer your question, Yes I did position the Step 2" in front of the most aft c of g. The end result is that the Empty Weight CofG is right on the Fwd Limit. (I do have an Airmaster prop, and Battery on the firewall though) so that also moves the CofG fwd. in fact the setup is pretty much the same as the CofG when it's on wheels. I've finished the flight testing now, and will not change anything. I did fabricate a larger Header tank which I have installed on the rear bulkhead. It was more so for the extra fuel rather than for CofG. If I was to do it again I would still use the same setup, as I can load it up without any CofG issues.


Correction: just read this again and realised it is wrong. STEP IS 2" AFT of most rear CG.

Re: Rigging Floats on the Highlander

PostPosted: Thu Feb 09, 2017 8:42 pm
by pt17

Re: Rigging Floats on the Highlander

PostPosted: Fri Feb 10, 2017 8:58 am
by gkremers
Nice video..... I'm in Michigan, middle of the winter and can't wait to get the floats back on.

Gary