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Engine Start without wings on?

scottmillhouse

Well Known Member
I know you should never start a big bore Lycoming on a not fully assembled RV due to shaking dynamics. Anyone have experience with the small bore smooth running Rotax? Helping a friend do ALL the SBs and Rotax replacements on an older plane that has not been flown in about 5 years. With most all done he is itching to run the motor at his shop before painting to validate all the updates and replacements. I know it is not much work to reinstall the tail and wings but there is not enough space.
 
Have you asked Van's? I'd like to hear what they say about this, or perhaps they've already addressed it.
 
There isn't any way a Rotax is going to torque it over on it's side, but the normal precautions of tie it to something substantial with a suitable robust rope or cable and don't rev it's nuts off.

We ran our 7 like that to check systems, leaks etc etc and am glad we did - found an ignition issue that could be fixed at the shop, not easily at the field.

As with anything, prep, check, ask yourself is it safe, don't let it lead to a Darwin event :D

Finally, if it does, make sure you have video and get your $250 :rolleyes:
 
I tied mine down to a tree with wings off. I didn't have a problem.

That is what we were considering. I did the same for my old Kitfox for a full Rotax 2 cycle engine breakin. I was thinking that since the 12 has the structural wing box beam the fuselage is at full strength where the other RVs need the wing spar bolted in to complete the fuselage structure. Just planning a short run probably just to 2500 rpm to validate ignition and fuel systems.
 
I remember Bob tied his 6A to a couple of stakes and maybe a tree when he tested that engine. But he did have the wings on.
Don't forget the fire extinguisher! We had no fires but I was ready just in case. 😀
 
I was thinking that since the 12 has the structural wing box beam the fuselage is at full strength where the other RVs need the wing spar bolted in to complete the fuselage structure. Just planning a short run probably just to 2500 rpm to validate ignition and fuel systems.
The reason it is not recommended on the other RV models has nothing to do with fuselage strength (and it is not because of a fear of it rolling over). It is because of the inertial damping in roll that the wings provide.
The majority of the shake induced by a Lyc. is in roll. Without wings installed, there is much less mass to limit the shake.
There are documented cases of RV's having elevators and rudder damaged because of an engine start/shut down without wings installed.
Can it be a problem with an RV-12? Probably not, but I cant' say for sure because we choose not to take the chance.
 
No wings start

I have run mine three or four times without the wings on to sync carbs or warm the oil prior to changing. Always chock the mains and use a strap on the tail tiedown to my truck. Nothing has fallen off yet.
 
I too ran mine without wings like the prior post, and had no problems but was cautious. No taxing or full power run ups and nothing felt unsafe or being over stressed.
 
True story for your amusement (or horror).

We had a local gent who was syncing the carbs on his 912-powered Rans S12, with the wings off. Following a cable check he left it at WOT, forgot about it, and later hit the start button. Luckily he was leaning into the cockpit and the gear leg knocked him down when it jumped the chocks, so the Warp Drive missed his head. No, it wasn't tied.

Anyway, the wingless Rans went straight up the hangar row, gaining speed like a prop-powered drag racer. It was running at least 100 mph when it hit the old line of pine trees at the north end of 08A, almost exactly 1/4 mile from the starting line. The nose wheel hooked the berm, and it flipped up to go in prop first, like the big tree saws used around power lines. The Warp actually cut through a bunch of saplings and a 6" pine before failing two blades in some 8" and 10" trunks. We were impressed!

I suppose the moral of this story is obvious enough ;)
 
I taxi tested my LNC2 for a short distance without the wings. It scared the **** out of me because there was no rotational mass about the vertical axis and the aircraft wanted to careen left and right. Even now that it's been flying for three years, the plane can be squirrely on the runway with no fuel in the wings. (The ourboard wings only weigh 50 lbs. empty)
 
I put the wings on for the first start. After that I ran it several times without the wings (too much trouble putting them on and off). It's a non issue. It's not going to rotate or vibrate or go anywhere - unless you drive it down to taco bell:)
 
I did my first run with the wings off and just held the brakes. I had no issues except that it crept forward at high RPM because the brake pads hadn't been conditioned.
 
To come to closure, we ran the 12 today without the wings with no problems. First engine run in 5 years with all engine and full system updates and carbs rebuilt. Of course carbs still need synced and there are minor issues like the fuel pressure sensor is grounded, one EGT is open and the Dynon backup battery needs replaced. A shoutout to Lockwood for their carb work- fired up immediately and idled smoothly at about 1650 rpm.
 
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