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-   -   Starting Engine In Drive-Way (https://vansairforce.net/community/showthread.php?t=55707)

DanH 03-19-2010 07:20 AM

FWIW, I've also witnessed an RV6 started without wings, no problem at all, shake or otherwise. Of course the owner was smart enough to tie it to a truck......

That said, I don't recommend it for the reason John mentioned; you don't want to unpickle until time to start flying.

aerhed 03-19-2010 09:55 AM

Guys around here do it all the time. We call them snowplanes. My buddy has the one Sparky Imeson's dad built with a C-85. Real fast, real spooky.

jcbarker 03-27-2010 09:38 AM

Proof of an -8 started without wings
 
No big deal. Like Dan said, no shake. Probably didn't need the side tie downs but it was easy to do. Good chalks under the wheels and you'll notice we tied the tail to a tractor! As you can see, the airplane was done. So it didn't have a chance to sit around long before it was flying.




Junglepilot 03-27-2010 04:31 PM

No problem if you take precautions
 
When I was overseas with MAF, we had a Cessna 180 that had it's wings off for extended maintenance that we did not want to have corrosion start in the engine. So we ran it every week.

We took a spare/used oil external oil sump from another 180 (which held about two gallons if I remember) and mounted it securely to the right wing root, ran the proper hose and with fittings into the header.

We then pulled it out to an adjacent field next to our main hangar, tied the tail wheel to two in ground heavy duty tie-downs, set the yoke to full up elevator, set brakes and chocked the wheels with oversized, metal chocks.

Next had a man stand buy with a large halon extinguisher.

We ran it this way each week for about 5 months until it was back in service. The engine went to TBO and no surprises.

Just use common sense. That video with the Lancair is indeed sad but that one leg look tweaked when the video started. I believe there's more to that story than the 10 seconds of shakey footage show.

az_gila 03-27-2010 08:22 PM

The other problem...
 
...may be blowing your neighbors roses away....:)

One S. Cal builder showed how this could be done... and another started his engine in a small enclosed back yard, and didn't warn his wife, who was p***d off that all of the back yard dirt blew into her kitchen....:mad:

Those large propellers do create a lot of "wind"....

Andy Hill 01-04-2011 03:29 AM

Whilst building the RV-3 fuselage, it suddenly struck me there was a discontinuity in major longerons in the lower fuselage between the main and rear wing spars...

It made me go back to the plans and check I had not omitted something... and then realised, no I had not, the "load" path is provided by the wing structure itself.

If you do choose to run the engine without the wings bolted on, think through how the "box" rigidity of the fuselage (in twist) is compromised by no wing box, and also the straight line path from engne to tail (i.e. tying the tailwheel down does not really help since there is a structure "gap" between the wing spars). Trying to quantify these elements is nigh on impossible - the only people qualifed to answer are Vans, and we know their opinion on the matter ;)

Andy

WenEng 01-04-2011 05:23 AM

An RV10 no wing engine startup. No problem.
 
http://www.youtube.com/watch?v=0LgG6J8UyPE&NR=1

That being said, I will still wait for my wing attachment before running mine the 1st time. A couple years ago I wanted to start it sitting on an modified engine stand w/o prop. But, back then I was considerably more ignorant than now..... Now, I'm only slightly ignorant... big improvement thanks to VAF...:D

Ironflight 01-04-2011 06:12 AM

Quote:

Originally Posted by Andy Hill (Post 500330)
Whilst building the RV-3 fuselage, it suddenly struck me there was a discontinuity in major longerons in the lower fuselage between the main and rear wing spars...

It made me go back to the plans and check I had not omitted something... and then realised, no I had not, the "load" path is provided by the wing structure itself.

If you do choose to run the engine without the wings bolted on, think through how the "box" rigidity of the fuselage (in twist) is compromised by no wing box, and also the straight line path from engne to tail (i.e. tying the tailwheel down does not really help since there is a structure "gap" between the wing spars). Trying to quantify these elements is nigh on impossible - the only people qualifed to answer are Vans, and we know their opinion on the matter ;)

Andy

It really is amazing what we are learning by actually BUILDING our aircraft structures, isn't it Andy? The load paths are much more understandable when you put them togteher....

Paul

Bill Wightman 01-04-2011 10:39 PM

RV8 Driveway Run
 
Ran up my RV8 / 180 CS sans wings without issue. *However* there could have been problems stemming from a couple areas.

Video Link:

http://www.youtube.com/watch?v=JHQfhOiyKQM

Tail shake: Mine didn't seem to have a real issue with tail shake, but I couldn't have known that at the time. Its since been brought to my attention that the wings do provide a good amount of mass damping to the fuselage and will help to reduce tail shake during startup/shutdown.

The wings also contribute a good bit of weight to the tail so the plane is considerably lighter on the tail without wings. My solution to that was to tie the tailwheel spring to the rear axle of a Chevy 1500. But that still wouldn't prevent it lifting up a couple feet with enough thrust up front.

Second: the torque impulse reacted by the landing gear looked worse on video than it felt in the cockpit. In the video, you can see both gear legs flexing a fair bit as the engine stumbled to life out of a slightly flooded state. To me, it didn't feel or look unstable or apt to tip over but the torque reaction, being entirely reacted by the gear & fuselage inertia, was somewhat more than I was accustomed to.

Y'all can draw your own conclusions. I for one didn't have any problems. But, the wings definitely do contribute additional mass stability to the airplane so if you feel like you need that, then by all means put them on. I personally have no fear of a tip-over so long as the airplane is secured to something that won't move, as was evident in the video. Structurally, I see no reason the wings need to be on for a simple ground run, other than their mass damping effect. They definitely do not add stiffness to the fuselage. The spar carry-through section is stiff transversely, but that stiffness isn't critical for this kind of operation.

kentb 01-05-2011 11:01 AM

I didn't start mine until the day before the first test flight.
 
I didn't avoid the early start up because of structural reasons, although it looks like that should be considered.

The reasoning used for the delay about starting the engine are as follows:

I try to fly my plane once a week. If for some reason I can fly for a month, I start getting concerned about not doing the best for my engine. If you keep the oil moving on a regular basis your engine will last longer.

My engine was shipped to me with preservative oil in it and was setting in my hangar, on a pallet and then on the plane for more then one year. Before starting the engine the oil needs to be drained and fresh oil put in.

After the first start the engine is in the non preserved state and the clock starts ticking. Now the pressure is on to get it in the air and I don't like being under pressure to complete the build. At the end stage of the project you need to take your time and make sure everything is right.

Kent


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