Hi Jemo,

Many thanks for your suggestions. I will incorporate them on my Stinger. Your sketch was perfectly fine and will also be a modification on my Stinger 120.

Dave K

A few comments that I have read about the Stinger 120 wing being subject to failing in flight have interested me since I have started building mine and don't want to re-kit it during flight.

Some issues that I would appreciate comments on:

1. No one has indicated just where on the wing the failure(s) ocurred. Was it at the centerline?
Was it at the area where the plywood spar doubler ends? To the best of my knowledge,
These are the only areas that could fail due to an over-stress situation.
2. Assuming that the foregoing is correct, it would seem that if the failure was at the centerline,
strengthening the area with fiberglass should solve this condition. If the failure was at the
end of the plywood spar doubler, then adding a series of lightening holes with the largest
at the outer ends of the spar doubler and progressively making the adjacent holes smaller
would reduce the stress riser and allow the wing loads to transistion from the outer wing to
fuselage structure.
3. Rather then replace the balsa spars with hardwood and add weight, would running carbon
tape on top of the spar area be a lighter and much stronger way of strengthening the wing?

4. In addition to reinforcing the wing saddle area with plywood doublers, would running carbon
tape fore and aft along the bottom and sides of the fuselage be a good idea?

Thanks

Dave Kovensky
[email protected]

I heard the wings failed at the end of the ply spar doubler.

All your suggestions sound good. On my Ginat Stinger, I added some fiberglass tape over the spar extending 6" out from the doubler. I have flown the stinger hard for several years, no failure. If I had carbon fiber, I would have used that.

I did get a crack in the fuse at F2 on a landing I hit a deep rut. I had added some fiberglass to the inside, but needed more.

Hi Scott,

Thanks for your prompt response. What did you think about my idea of not only beefing up the fuselage with a ply doubler, but adding carbon fiber strips as well?

Dave K

Hi Jemo,
I'm a little confused here. The drawing you did of the 1/4 plywood, was that behind the firewall or on the fuselage bottom for the landing gear? I'm glad I read these posts, I forgot to put the fuselage doublers in. Gotta go do that today. Can't fly, been raining since last evening. Everything's muddy as all get out.

Jim,
That brace is on the top. If you look at the firewall of the stinger, it is not really supported on top, it has plenty of support on three sides only, so I added a brace. It proved to be a good idea.

I may have doubled the gear block, but I don't really remember.
The big thing is the doubling of the side's. When you look at any stinger from the side, without the wing on it, you will see how weak it is at the leading edge of the saddle. I have seen many stingers break at that spot (all size stingers). I ran my doubler from F2 all the way back to the rear of the saddle. I eventually demolished the stinger (really bad) but it never broke there.

Jim

Ok, Now I understand. This is a good idea! My firewall looks good as is, mainly cause I cut it out and moved it back 1 1/2", pinned it, fiberglassed it, and reinforced it. Didn't think of putting brace on top. Guess I"m not finished with it after all. Gonna go add doublers, and 1/4" ply brace.

I weighed it yesterday and it came out 14 lbs 6 ozs. Not too bad I guess. Wing loading came out to 24.6 oz/ft.sq. That should make a good flyer. If this dang rain and cold weather will go away I'll let you know how she flies.

What weight did you other guys come out with on your Stingers? I got 14 lb 6 oz.

I had my firewall back and pinned also.
I can't remember the weight, but it flew great. I used a bit of spoilerons for landing to keep it from floating, worked well.

My G-38 was just getting nicely broken in, running like a charm. I decided to remove it and try a new engine on it just to get it broken in. Welllllllll. That was the day I applied an extreme amount of turf to the nose, it wasn't pretty.

My super running G-38 is still sitting on the shelf and I swear I can hear it laughing at me from time to time.

I know the feeling. Mine is an OS 160 that chuckles when it thinks I'm not looking.

Saturday came and went uneventfully as I didn't fly anything. Sunday was a different story though. Took the Edge 540 w/ OS 160 in it and the Stinger 120 w/ G-38 in it to the field. What a great day of flying. As usual, the Edge acted up and gave me fits but I think I got it straightened out pretty well. Flies good but just likes to act like a bonehead.
On the other hand, the Stinger was a dream. That thing doesn't know the meaning of bad flying.
Virtually had to make NO trim adjustments except for a couple of clicks of down elevator and it took off like a dream. Flies like it's on rails and floats gently to the ground with little to no roll out on landing. Had a 20 X 8 MAS prop on it and that's just too much prop. Got a 18X8 MAS to try Wednesday. Should make a ton of difference. This plane should be a prereq for anyone getting into large gassers. Excellent plane.

Well, as all things cannot stay good forever, the Stinger showed one very nasty flaw that really made me mad at Lanier. The plywood on the fuselage bottom SUCKS! On the fourth flight when I was landing, the plywood gear plate simply came apart and the gear flew across the landing strip. This was not even a firm landing, it was soft and POW, off came the gear. It's in the shop now getting a new floor and reinforcements for the gear and new belly covering. Will have it all done tomorrow.
It just pi$$e$ me off that these companies don't put more quality into their products. I would be glad to pay another $5 or $10 for quality landing gear mounts, cowlings, and fuselage bracing where needed.
Anyhow, I can't wait to get her back in the air. I think the Extra 300 has been replaced as my favorite airplane.

Later,
Jim

Jim,
That long narrow gear on the stinger puts a lot of stress on the gear plate, but you will get it sorted out.

I tried many props with my G-38/Stinger also. It seems that a 18 X 8 or 18X 10 are the best combo, the 8 giving a bit higher RPM which was nice. I had tried a 20 X 6, which gave it a lot of thrust for hanging but I didn't like it because it was sooooooo slow.

Forget the little engines on the Stinger 120 go for it and put a g62 on the nose it is a great combo. To do this just cut 3 inch off the nose place the battery and servos in the tail and reinforce the wing with carbon fiber you will not regret putting this engine on this airfram it is great. any questions Email me at [email protected]

Already got another engine on the stinger. The G-38 is on the bench and I have a 25cc weedie on it. It's slower than is possible but it performs flawlessly. I never have been into 3D stuff so that is not a consideration. I'm old and my reflexes are too slow.