adding weight to the tail

[brilenz]

looking to see how others have attached weight to the tail. My CG is such that it a 3-point landing is nearly impossible. Any one have any solutions?

[jmodguy]

Dive weights are easy to strap down with some large zip ties. Another option is a steel plate and adel clamps.

[jiott]

Install a gap seal between horizontal and elevator. Don't use full flaps; 1/2 flaps work fine.

[airlina]

Tommy, I built a Series 5 with a Continental IO-240 up front so my battery is in the empennage like yours. I used the standard attach method as specified by Skystar's instructions. This proved to be a near disaster for me. The instructions called for 6 adel clamps in various spots to secure the battery tray. this proved to be woefully inadequate. during preflight one day I noticed what I thought was a mud spot just below my battery area on my fabric. When I tried to rub it off , I found it to be something hard protruding thru the fabric from the inside. I immediately took off the battery access cover and was shocked to find that 5 out of my six battery attach points had failed and the battery and tray were floating just above my rudder cables. The adel clamps had torn completely, as well as the aluminum angle at the back corners of the battery tray. . i suspect this occurred during spin testing and recovery as the torque forces in the tail must be strong during recovery. as you can imagine had i not found this before flying , it could have been a disaster in flight , with the proximatey of the elevator tube and rudder cables in this area. i changed the whole attach method after this incident and put out a service bulletin to alert others that had their battery in the tail like us. I am going to attach photos of before and after to show how i fixed the problem. I have spun the airplane with this setup with no ill affects. Suffice it to say that I will never trust adel clamps to secure anything to the tubing that has any weight to it. My new homemade tube clamps are made from 4130 steel tube and are the same strength as the airframe. sorry about the longwinded answer but I felt this to be a serious safety issue with the battery in the tail. by the way , I use an Odyssey PC 680 battery that weighs 16 lbs and measures 7.15" long by 3.00" wide by 6.65" high.

I would like to caution those adding weighty objects especially in the empennage to secure them with more than zip ties or even adel clamps . The forces during flight are more than you think as you can see from my old post above from 2012. I now make up "dutchman clamps" for attaching any weighty objects in my airplane. Bruce N199CL

[PapuaPilot]

I agree with you Bruce. I thought the same thing when I saw they wanted to install the battery tray with adel clamps. zip ties aren't a good idea, they will age and break.

What are Dutchman clamps?

[JayHenry]

I would love to see the pictures of your fix with the"dutchman clamps". I am about to start on the project of adding battery weight in the tail on my STi soon.

Thank you,
Jay


I would like to caution those adding weighty objects especially in the empennage to secure them with more than zip ties or even adel clamps . The forces during flight are more than you think as you can see from my old post above from 2012. I now make up "dutchman clamps" for attaching any weighty objects in my airplane. Bruce N199CL

[Dusty]

If you have a pneumatic tail wheel,fill it with antifreeze. An extra leaf for the tail Spring also helps.

[n85ae]

I have 15 pound of ballast in the tail, and it's secured by 8 mock Adel clamps that I made
out of 4130, pretty sure if the ballast tears loose I have very serious "other" problems

The ballast I have is a 2" square tube filled with lead and that I welded tabs onto

For my airplane with IO-240B it was well worth the effort to install it.

Jeff

[n85ae]

Here's some pics I made a long time ago about forming 4130 Adel's ... I omitted a few
pics but you get the idea. Basically I just beat a piece of 4130 around a drill bit the size
I needed using a plastic hammer, a vice and some imagination. Pretty simple project.

Jeff


25941

25938

25939

25940

[JayHenry]

Thank you Jeff Awesome idea!

[n85ae]

Thanks! I have a few more pics of the sequence that I left out, but I figured you would get the idea from
these ones.

Bruce made some nice clamps as well, hopefully he's got a few pics. We were discussing the battery box
install as well at the time I made these since neither of us was very happy with the factory box.

Jeff

[airlina]

As per a few requests here are some photos of the "dutchman clamps" that I used for the battery tray adel clamp failure as previously post in this thread. For some poor quality photos of the before and after repair search this post on the forum: "SS with continental engine battery placement". The clamps are simply made from 4130 tubing that is sized by measuring the O.D of the structural tube you want to clamp on to, then going to aircraft spruce and finding the tube with an I.D. to fit around that tube. Two 4130 tubes are then welded perpendicular to the clamp tube to accept the AN3 bolts I used to clamp it together. I then spilt the whole shebang in half with a dremel fine metal cutting disc. They are incredibly strong and clamp tightly to the tube with no slippage. As you can see in the photos I added a tab to one and used it for my homemade trim assist kit. Also used for header tank , A/P servos and the battery tray fix. I've been told these were used on many WWII aircraft like the B-17 , so good enough for my Kitfox. Bruce N199CL

[JayHenry]

Another brilliant fix! Thank you for the pics.
As per a few requests here are some photos of the "dutchman clamps" that I used for the battery tray adel clamp failure as previously post in this thread. For some poor quality photos of the before and after repair search this post on the forum: "SS with continental engine battery placement". The clamps are simply made from 4130 tubing that is sized by measuring the O.D of the structural tube you want to clamp on to, then going to aircraft spruce and finding the tube with an I.D. to fit around that tube. Two 4130 tubes are then welded perpendicular to the clamp tube to accept the AN3 bolts I used to clamp it together. I then spilt the whole shebang in half with a dremel fine metal cutting disc. They are incredibly strong and clamp tightly to the tube with no slippage. As you can see in the photos I added a tab to one and used it for my homemade trim assist kit. Also used for header tank , A/P servos and the battery tray fix. I've been told these were used on many WWII aircraft like the B-17 , so good enough for my Kitfox. Bruce N199CL

[brilenz]

If you have a pneumatic tail wheel,fill it with antifreeze. An extra leaf for the tail Spring also helps.
Great idea- not sure why i didn't think of this- I do it with my tractor why not my plane! Thank you!!

[brilenz]

I have 15 pound of ballast in the tail, and it's secured by 8 mock Adel clamps that I made
out of 4130, pretty sure if the ballast tears loose I have very serious "other" problems

The ballast I have is a 2" square tube filled with lead and that I welded tabs onto

For my airplane with IO-240B it was well worth the effort to install it.

Jeff

Is this snuck in and secured thru the rear inspection plate? My thought was to run a string from up front down thru the rear inspection plate and zipline a dive weight or two down to the rear and somehow secure them in place to the frame...logistics are still not perfected in my head yet...

I like the 2" tube idea though.....

[brilenz]

Install a gap seal between horizontal and elevator. Don't use full flaps; 1/2 flaps work fine.
That was my initial fix....no joy even without flaps. Elevator gap seal does seem to help a bit, but not quite enough

[Eric Page]

Do you have vortex generators under the horizontal stab? That may give you a bit more elevator authority as well. AS&S have them in small packs for tail installations.

https://www.aircraftspruce.com/catalog/appages/stolspeed.php?clickkey=8248

[brilenz]

that's my next project both stab and wings

[n85ae]

I think I had the Horizontal Stab out, and a combination of through the Battery panel, and from the
top. The IO-240B build has a big battery access panel right under the Horizontal stab. Not sure about
other models.

I would not think of any weight in there unless it is SECURELY tied down. I know at least one kitfox
<builder name shall remain secret> that was doing spin testing and the entire battery box tore loose ...
So I would say you want something very strong holding it.

Vortex generators might help, but proper balance is probably the better choice. I can tailwheel first
N85AE without any difficulty, and never have Elevator authority issues and I have an IO-240B


Is this snuck in and secured thru the rear inspection plate? My thought was to run a string from up front down thru the rear inspection plate and zipline a dive weight or two down to the rear and somehow secure them in place to the frame...logistics are still not perfected in my head yet...

I like the 2" tube idea though.....