Spin Testing "Fun"

Ironflight · #1 11-10-2005, 07:25 AM

I don't know whether to call this a tip, a warning, ...or if it is jst to give everyone a good morning laugh, but here goes...

The last few days I've been doing the aerobatic portion of my test program on the -8. Loops, Rools, Split S's, - all the fun stuff. I realized I hadn't done any spinning yet, and kind of chided myself - I usually want to know the spin characteristics before the other things, in case of a blown manuever.

Anyway, I put some spins on my test card for yesterday, sneaking up on them with some slow flight and stalls. I had read everything in the flight testing section of the assembly manual on spinning the RV's, and was ready for anything, but expecting nothing extraordinary. Pulled it up into a stall, kicked left rudder, and she shuddered a bit, fell off as expected, and the nose sliced down about 30 degrees past vertical. At that moment, I got a little negative G, I heard a big "Bang" behind me, there was a moment of chaos and lots of dirt flying around, and I figured immediate recovery was in order. I never let the spin develop beyond a half turn, and she popped right out, with no difficulty on the pull-out...

Immediately concerned about the "Bang", I checked my mirrors to make sure the tail was firmly attached - nothing appeared out of place, and the airplane flew fine. OK Paul - catch your breath....and then begin laughing! You see, I am carrying about 80 lbs of ballast in the aft baggage compartment to bring my CG to about mid-range - she is really on the forward line with just me and full fuel. My ballast? Two 40 lb bags of readymix concrete! It's been in there since the first flight, and I really haven't thought about it - I've added more or less ballast to the rear seat during CG range testing, and strapped that down with the harness, but on this flight, I just had my "normal" ballast...

Well folks, there aren't any baggage tie-downs inside the rear bin, so when I unloaded in the spin entry, those two bags decided to vist the top of the baggage compartment. One of them hit an edge, or maybe the shoulder harness bolt, and tore a hole in itself - releasing that fine gray concrete dust! Fortunately, no damage was done to the airframe, and the ShopVac cleaned up the residue post-flight. I think for future Acro testing, all ballast will be strapped down in the rear seat - lesson learned!

Paul

Mel · #2 11-10-2005, 07:40 AM

Great information, Paul. There was a fellow killed in a Dragonfly back in the '80s. He was using bar-bells for ballast. They came loose and hit him in the head. PLEASE make sure any ballast is secure before flying.
Mel...DAR

Mike S · #3 11-10-2005, 08:20 AM

Be sure you have all of the concrete dust out of there----remove any panels you can un-bolt, and vacuum very well.

Concrete is not kind to aluminium---------very alkaline if my memory is correct, and any moisture (like condensation) will make it even worse.

Mike

szicree · #4 11-10-2005, 10:48 AM

Quote:

Originally Posted by Mel

There was a fellow killed in a Dragonfly back in the '80s. He was using bar-bells for ballast. They came loose and hit him in the head.

Guess my old CFI was wrong when she said you can't get hurt in the air!

Steve Zicree

rv8ch · #5 11-10-2005, 01:23 PM

Quote:

I don't know whether to call this a tip, a warning, ...or

Thanks for the tip, and I'm glad nothing bad happened!

Tom Maxwell · #6 11-10-2005, 01:58 PM

Quote:

Originally Posted by Ironflight

I don't know whether to call this a tip, a warning, ...or if it is jst to give everyone a good morning laugh, but here goes...

Dang Paul, I surely didn't laugh. That scared the bajeebers out of me and I wasn't even in the plane with you. I guess it is a good thing Van designs em tough. Your checking to see if the tail fell off could have very easily been a reality and we could be reading about you on the NTSB web site.

I know you don't need a lecture but my goodness a projectile can turn a perfectly good plane into a disaster in the blink of an eye. Please everyone make sure everything is tied down securely in your planes before firing up the engine. One never knows when some unexpected turbulence might be encountered. Even something as benign as a jacket or a pillow flying around the cockpit can result in some serious distractions or worse.

Thanks Paul for sharing this with us. It should make us all stop and think. Paul is obviously a very experienced pilot and this illustrates that it can happen to evern the most experienced pilots. Let your guard down for just a moment and the laws of physics can ruin your day.

Ironflight · #7 11-10-2005, 02:53 PM

I have a pretty unique positon and a huge respect for Flight Safety in my job - and one of our rules is to always share the bad stuff, even if it makes you look silly! Hope someone learns from this.

For those not familiar with the -8, I wasn't at all worried about the ballast being a projectile in the cabin - it was well contained by the rear seat back, which was secured witht he harness. I had done THAT much pre-planning!

And concur on the conrete dust - I cleaned it up very thouroughly. Thought I'd planned ahead for that too, with the bags wrapped in plastic bags and then in some old shirts. It was OK while they stayed put - just didn't hold up to a short flight around the baggage bin!

.....and some day I'll tell you about the noise a decorative mylar ballon makes when it ruptures just behind your head (in the baggage area of a Yankee) as you climb through 10,000'. It definitely gets your attention!

Paul

Kevin Horton · #8 11-10-2005, 03:59 PM

Paul,

Thanks for sharing your story. It really drives home the point that any ballast should be very well tied down. This is true even if you aren't planning on aerobatics or spins, as loose ballast could do a lot of damage if you ever have a ground incident/accident.

I purchased some baggage tie down points from Van's that I will be attaching to the floor of my aft baggage compartment. I haven't figured out how much load I should assume they can take though. That bit of calculation is on my To Do list. I'm hoping my analysis will say that they can secure a reasonable ballast weight with a 9 x factor of safety (to cover ground incidents/accidents). But I'm not optimistic. I might have to back off on the factor of safety a bit to get the ballast weight up.

rv9aviator · #9 11-10-2005, 03:59 PM

A big bag of potato chips exploding will make you pee a little too. Don't ask me how I know.

flyeyes · #10 11-10-2005, 04:09 PM

Great post Paul.

I had a similar (on a much smaller scale) experience while recalibrating my AOA computer, which requires a 0 "g" pushover briefly. The thump from the baggage compartment as I recovered from the dive was accompanied by a little pitch excursion as the ballast firmly contacted the floor of the baggage compartment.

I have tried different ballast, usually 25# bags of lead shot for convenience although they are clearly not the safest. I have used concrete and "play sand" but the bags tend to leak.

My favorite, when expanding the envelope in an open cockpit tandem (AirCam) was large bags of dry dog food. Relatively cheap (if you already have the requisite large dog) and low enough density to be relatively safe in the event of a "Class A" incident. They are easy to strap into seats and easy to clean up if they leak.

James