Funkey retracts?
08-17-2004, 08:27 PM
#1
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Funkey retracts?
Anyone had any experiences good or bad with Funkey retracts? I got these with a Y/A f-18 single kit and they are a Y/A product. I purchased all of this from someone else but everything was new in box. I have been pleased with them until the wire snapped on the front strut today while I was doing some taxi tests. Now I'm questioning the reliability of these units. I didn't hit a very large bump and I wasn't going very fast either.
Thanks,
Brandon
Thanks,
Brandon
08-17-2004, 09:14 PM
#2
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RE: Funkey retracts?
Don't worry Brandon,
I had the exact same thing happen on the 1st flight of my stingray, and many others have similar stories. The nose gear pin should be replaced with 3/16" music wire with a small notch ground into it for the setscrew. Machining it like they did will give a larger stress concentration and the material spec seems far too brittle. As for the long term reliability, they are as good as the rest. They hold air for months, they're light, and can take some pretty good punishment (after changing the pin). I'll probably buy another set one day...
To change the pin, remove the brass part from the retract unit by unscrewing the small threaded retaining pin. It runs in a groove cut in the outside of the brass part. Heat up the brass on a hobby iron at max temp. Find some apparatus or bearing press to remove the pin, (such that the pin's damaged end comes out first). If there's any local deformation, you don't want it to score up the inside of the sleeve. Let the brass sleeve cool and press the replacement pin in with green loctite. I forget what loctite number I used but it should be a permanent compound for press fits. It can always be removed again with heat.
Good luck,
Kelly
I had the exact same thing happen on the 1st flight of my stingray, and many others have similar stories. The nose gear pin should be replaced with 3/16" music wire with a small notch ground into it for the setscrew. Machining it like they did will give a larger stress concentration and the material spec seems far too brittle. As for the long term reliability, they are as good as the rest. They hold air for months, they're light, and can take some pretty good punishment (after changing the pin). I'll probably buy another set one day...
To change the pin, remove the brass part from the retract unit by unscrewing the small threaded retaining pin. It runs in a groove cut in the outside of the brass part. Heat up the brass on a hobby iron at max temp. Find some apparatus or bearing press to remove the pin, (such that the pin's damaged end comes out first). If there's any local deformation, you don't want it to score up the inside of the sleeve. Let the brass sleeve cool and press the replacement pin in with green loctite. I forget what loctite number I used but it should be a permanent compound for press fits. It can always be removed again with heat.
Good luck,
Kelly
08-17-2004, 10:56 PM
#5
My Feedback: (2)
RE: Funkey retracts?
Barry might have a good point, although I'm surprised the viper doesn't spec larger retracts... At first look these seem a little small for a kit of that size.
Mine also bent slightly when I overshot a grass runway on my 2nd flight, but that should be expected based on the punishment I gave it... I was actually impressed how well they stood up to landing in the long grass. The dry weight of my Stingray is ~10 lb less than the quoted weight for a viper (according to Tam's site). An F-18 single may split the difference depending on how its built up and the choice of power plant. I bent the side frames back into place on the nose gear and watched for any more deformation, no problems in the following flights. Its probably more prone to bending now that it has plastically deformed once, but I suspect its ok.
Kelly
Mine also bent slightly when I overshot a grass runway on my 2nd flight, but that should be expected based on the punishment I gave it... I was actually impressed how well they stood up to landing in the long grass. The dry weight of my Stingray is ~10 lb less than the quoted weight for a viper (according to Tam's site). An F-18 single may split the difference depending on how its built up and the choice of power plant. I bent the side frames back into place on the nose gear and watched for any more deformation, no problems in the following flights. Its probably more prone to bending now that it has plastically deformed once, but I suspect its ok.
Kelly
08-18-2004, 10:45 PM
#7
RE: Funkey retracts?
Hi,
There wasn't a 'problem' (per se) with the wire, they simply thought a shear-pin would be a good idea. When they realized (due to feedback) that it was causing more problems than it was solving, they switched to a music wire. Yellow gear bought today won't have the shear-pin wire.
Dbarrym, the Viperjet uses YAC small gear?? I'm really shocked to hearthat. Seems to me that the airplane is a little sizey for those gear. As far as the side-frames being easy to bend is concerned, those gear are designed to be a replacement for the Robart/Springair gear we're used to in .90 size DF birds. Compared to those, these gear's frames are way stronger.
There wasn't a 'problem' (per se) with the wire, they simply thought a shear-pin would be a good idea. When they realized (due to feedback) that it was causing more problems than it was solving, they switched to a music wire. Yellow gear bought today won't have the shear-pin wire.
Dbarrym, the Viperjet uses YAC small gear?? I'm really shocked to hearthat. Seems to me that the airplane is a little sizey for those gear. As far as the side-frames being easy to bend is concerned, those gear are designed to be a replacement for the Robart/Springair gear we're used to in .90 size DF birds. Compared to those, these gear's frames are way stronger.
08-19-2004, 12:00 AM
#8
RE: Funkey retracts?
Hi Shaun -
Guess I should be more clear, I used the FK nose gear, not the mains, because the Robart unit I needed was not available. My VJ had a really rough landing (snap rolled about 2 feet off the deck during an emergency landing - the fin and rudder was fluttering, causing it to yaw side to side). The Robart mains, one of which was torn out, have no damage at all, while the FK frame nose gear was destroyed.
Not a fair test but I was surprised to see the distortion in the nose gear frame, as the nose gear mounts were not damaged at all.
Barry
Guess I should be more clear, I used the FK nose gear, not the mains, because the Robart unit I needed was not available. My VJ had a really rough landing (snap rolled about 2 feet off the deck during an emergency landing - the fin and rudder was fluttering, causing it to yaw side to side). The Robart mains, one of which was torn out, have no damage at all, while the FK frame nose gear was destroyed.
Not a fair test but I was surprised to see the distortion in the nose gear frame, as the nose gear mounts were not damaged at all.
Barry
