REFLECTOR: Fixed gear blow out

[John Abraham]

Chris,

 

You should be getting at least a 1.5" toe in on each side with weight on the
plane.  (1.5 each side towards nose, not 3 out on one side and 2 in on the
other or the plane will track sideways.

 

A toe out situation you can notice on takeoff and landing as you would feel
the plane skipping around as the gear springs back together.  How much taxi
testing have you done.  If you are ending up on the inside of the tires and
you had set the toe-in I would look at the base of the gear leg.  Make sure
that near the axle isn't bowed out.  If so the heat from the brakes have
gotten to your gear leg and warped them.  The main problem isn't when you
taxi out and takeoff, it is when you land fast (or taxi fast) and then go
park the plane and the heat can sit in one spot and heat up the leg.
Especially if you turn the aircraft 90 degrees tight and stop in a parking
spot and leave it.

 

If you are pushing the plane back in the hanger to maneuver other planes
this will also cause your gear to spread, which it should when you go
backwards.  We typically lift under the wing tips to allow the gear to suck
up back into place.

 

Tire blow outs I would also inspect to make sure the tube wasn't pinched in
the rim.  It won't necessarily blow right away filling it.  It does on a
landing due to the instant spin of the wheel though an causes it to tear
away from where it is pinched.

 

You should be wearing towards the outside of the tires if you have enough
camber.  The middle to outer 1/3rd of the tire should wear faster than the
inside and then flip at half its life.  When at gross the tires may be in
the center due to the weight of the gear and the spread.

 

Anyway, glad you and the plane are ok.

 

Fly Safe,

 

                      John Abraham

Chief Pilot, Executive V.P. Sales and Marketing

         4103

                  200 W. Airport Drive

                  Sebastian, FL 32958

             <http://www.velocityaircraft.com/> www.velocityaircraft.com

                  (P): 772-589-1860

                  (F): 772-589-1893

 

From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Chris Barber
Sent: Friday, January 24, 2014 1:35 AM
To: Velocity Aircraft Owners and Builders list
Subject: REFLECTOR: Fixed gear blow out

 

Well, on one hand I am pleased that when I did a quick loop of the pattern
after I got off work this morning (I just switched to graveyard shift this
week so get off work at 0700 hrs) my rotary engine ran smooth and strong and
seemed to be producing pretty kick ass power.

HOWEVER, when I landed, I had my starboard tire blow out. Yes, it is quite
the attention getter. I swayed slightly to the right of center of the runway
at LVJ and luckily exited the taxiway closest to my hangar.

I was able to get it back to the hangar. No damage to the aircraft this
time, not even the tire rim. But, I noted I had excessive wear on the inside
of the tire.....much more than i would have expected with only 15 landings
and less than seven hours of flight. I have done extensive taxi testing
though (basically having and expensive go-cart)

I had noted on my conditional inspection that I had uneven wear but it did
not seem that bad and I pledged to mind it. I concluded that the uneven wear
on the inner tire was due to the gear spread that I had noticed on my and
other canards (my hangar mate has a long easy and he is always lifting his
bird to get the gear from spreading after taxi).

Velocity is pretty specific on how to set the camber and recommend you set
the camber after installing the engine and wings, which I did.

When the gear is not spread, the tires set directly in the center "meat" of
the tire. However, I have now noted...with the consequences, that as the
gear spreads, there is a significant tilt to the inner edge of the tires
thus causing the wear.

The gear bow is provided in the Velocity kit and it quite sturdy. What am I
missing regarding the bow spread tilting the tire to the inside of the tire,
thus wearing in what would seem a less wear prone area? I am certain the
camber was proper when the gear is not spreading out. I remember how tedious
it was setting it, lowering the plane, checking, lifting, setting, lowering,
checking repeat a number of times to ensure the proper set (same goes to the
toe-in process), but it is significant enough from the spread to roll the
tire on the inner edge to cause a problem.

Before I drop a few hundred on new tire and tube and try to fly again, I
would like to figure out what I need to address. Is it just to re-set the
camber to be on the center meat of the tire when spread since this seems to
be the case when taxiing or is there something else?

Insight guys???? Discuss.

Thanks,

Chris 

 

cross posted to Canard aviation fourm

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