May, 2012 Model Aviation magazine

[ZenManiac]

Yeah, Baby! SSC!

(what happened to your posting from 8/21, Bruce? )

-= Dave

[Dr. Kamakaze]

I built an evader-type plane that I test flew last night. I used the plan design for the fuselage and put my wing and tailfeathers set-up on it (not a flying stab). I also modified the engine mount and put the engine on with the muffler pointed up instead of down to avoid having to make a skid plate to protect the muffler.

The plane flew ok, but would go into a weird snap spiral at times even with taming the throws down. The CG is where I usually set it with other combat planes and it did not feel tail heavy. Is there a reason why everyone has the muffler hanging off the bottom and use a skid vs mounting the engine the other way with the muffler pointed up? My wing saddle is made from plywood (I didn't have any G10) and is 2 inches wide...perhaps the wing is not stable enough? I have velcro on the underside of the wing to help secure it to the fuse and use a flat-bottomed airfoil at the root. I thought maybe having the rubberband hold downs just as screws on top of the fuse didn't give enough stability to the wing during high G maneuvers that caused some instability? On my phenceposts I have the rubberband hold downs mounted on the sides of the fuse. It was a repaired wing I was using that could have a warp to it too I guess.


I was mainly curious as to the engine mounting for SSC...makes sense to me to point the muffler up and not use a skid...

Andy Runte aka "Dr. K"
-TEAM KAMAKAZE-
RCCA #876
AMA #273119

[Bruce B]

The skid protects the prop. With the muffler up thE needle is down and it's more fragile than a muffler. It's easy to adjust it too with it pointing up. Are you using a flat bottom wing? If not, check the incidence.

[ZenManiac]

I didn't even question the engine mount, since the muffler-down is the same as I had on my original combat plane, a Skull Bandit, 10 years ago.
Geez I loved that plane -- you never forget your first, eh?

Probably the output from your exhausted pointing up is screwing up your aerodynamics, Andy

-= Dave

[EK]

Mounting the muffler up causes fuel lock problems when you're in a rush or just having 'one of those days'. Skids showed up on the Avenger to protect the high cost ultrathrust muffler in use when OpenB and 2610 were what was flown. Protecting the prop is just a added bonus.

Sounds like you have a twisted wing. Stick it through the rungs of a chair and counter twist it and hit it with a heat gun. Take 1" strips of bidi and put them diagonally from TE tip to LE about 2/3 the distance to root (or vice versa depending on which direction to untwist it) will help stiffen the wing too. Maybe need a couple about 2-3" apart and don't be afraid to hit those with the heat gun either. Works about 50% of the time for me.

[Dr. Kamakaze]

Evan,
That would explain why I got hydro lock on the engine twice last night...I'll have to look at the wing closer for a warp. The fuse does seem solid and I didn't have to bend it over my knee like the phencepost
I'll keep tinkering with it,
Andy Runte aka "Dr. K"
-TEAM KAMAKAZE-
RCCA #876
AMA#273119

[ZenManiac]

Maiden flight today, SSC Evader.

Weather: 85 degrees, wind 10-15 from the south.
Plane: Evader SSC, new Magnum 15 (broken in), Mike Fredricks wing from my phencepost.

I never flew a flying stab plane before, so I was a little nervous about too much throw on the H-stab. I set up the dual rates with a 20% (about 1/4" up.down) and a 50% rate (about 3/8" up/down). I started at high rates, in case the trim was BAD. The plane flew out of my hand, and with a click or two of up and a couple of clicks of right, the Evader was flying like it was on rails. I like it!!!

It could have used more elevator -- even high rates made smooth carved turnes but not as tight as I'd like. Mental note to make the low rate setting as the current high rate, and add another 50% for the high dual rate.

Mental note #2: this plane doesn't turn like my 3D electric Sniper with snap flaps. I hate it when I stress test a new plane on the maiden flight: I turned inverted to check the CG, decided I didn't have enough elevator throw to hold inverted for long, and tried to recover with an inside loop. Unforturnately the loop was 40' diameter and I the plane was 30' above the ground. The good news, the break-away motor mount (zip ties) worked fine, the fuze was fine. I could have been back in the air in a few minutes if not for the throttle linkage breaking away an not having another connector.

Bottom line: I had to add some weight to the nose to get the CG right, I either need to move the wing back behind the start of the V-stab, or add some weight. I also made a 28" fuze, which will give a little more flexibility on the CG without too much weight penalty.

Thinkin' I might migrate my phenceposts to Evaders I really need to standardize all my planes, and I think this may be the planform!

-= Dave

[Bruce B]

That's awesome Dave, thanks for the report im glad it flew good and wasn't a bad crash. I mount the battery as far forward as I can and everything else where it has to go and adjust the wing for cg. I use a 6.6v LiFe battery and gws servos. I am usually just under weight or right at it with this plane if you don't go crazy with the bidi. I'm not sure about your wings, but mine will turn inside or outside equally well. As far as elevator throw goes, i set my radio to the elevator hi rate adjustment before I launch. climb high and do tight loops. You can turn it up or down while in the air. I set it till it just snaps out of a loop and then back off just a little. If you are a stick banger you might want a little less than that.

[wtsidney]

Flew the Evader - Feels very different than twin rail Lethal Weapon in the air. I think I'm going to like it once it is dialed in.

Setting up for Limited B with a .25 on it and a 25gram servo on the tail. Haven't got the CG dialed in yet.

Started with the wing saddle at 5" 1/4 from front of rail. CG was just behind the spar when measured with my finger tips. I liked how it turned, but when inverted the tail would drop and the plane would climb at a 45. In a dive, it would tuck. Figured it was tail heavy.

Moved the wing saddle to 6" 3/4. CG is 1/2" before the spar. This elminated the tuck in the dive. But very nose heavy. Will try to moving the battery further back. Don't have much room to move the elevator servo the way I mounted it on the rail. Expect I will be moving the wing forward.

[Quickdraw]

Looks good Bill. You need to get a few of those together and fly with us at the Texoma Nats in October.

[Bruce B]

I agree with David! You should come to the texoma Nats! Its always a good time , but with the gang we have flying around here you may want to build more than a few.

[Quickdraw]

OK, more than few. Since its a long trip to Sherman (for some people) might as well get an SSC fleet and fly Saturday and Sunday.

[wtsidney]

Been flying and tweaking the evader - but can't seem to get it to land on a grass runway without cart wheeling tail over nose.

Have tried a couple of different shaped 1/8" lexan skids - but as soon as the skid touches it sticks. Any thoughts or ideas?

[Blue Note]

Been flying and tweaking the evader - but can't seem to get it to land on a grass runway without cart wheeling tail over nose.

Have tried a couple of different shaped 1/8" lexan skids - but as soon as the skid touches it sticks. Any thoughts or ideas?

I think the sharp front edge and short skid is basically acting like a brake. Here is the way I use to make mine. They worked very well for a smooth landing. Attach a little forward and let it pass under the leading edge of the wing. They are durable, but can get a little heavy and expensive if you use too much material. Also, these skids are made of 1/4" nylon.



I now just use a bent piece of 1/8" fiberglass rod for a skid. The ends are just sitting into small pieces of 1/4" nylon blocks pop-riveted into the rails. Ideally, place the low point of the arc a little more forward than shown ( slightly in front of leading edge ) and stretch it out about 10" tip to tip to decrease the tension on the FG rod. This method has proven to be very light and functional. A bad landing may break the rod, but save the plane. Replacement takes about 5 seconds...literally. These images should show the basics.








Both of these methods will require slight changes to work with your plane, but the concept should apply. I think the FG rod would be the easiest for your installed basically by just drilling a couple holes in your fuselage at about 45 degrees or so. Since your engine is a sidewinder, and your muffler needs some protection, I might consider a 5/32" rod for the extra insurance. Test your bends before you commit.

Good luck!