RV-8 Excess Cabin Pressure

[John Clark]

Originally Posted by flickroll

And I get mine down low (denser air), and fast, with the vents open, never with the vents closed.....go figure.

When my -8 carries me back to 'ol Virginny late this week I'm gonna do a lot of experimenting when I get home and see if I can figure something out. Thanks for the data Paul, your test flight information is very valuable.

In my '8' it is the rear vent making the "buzz," closed, no noise. It varies with airspeed, so I assume that it has to do with the NACA intake under the wing.

John Clark
RV8 "Sunshine"
KSBA

[almarsh]

I HAVE RECENTLY FLOWN WITH BUILDER AND THOUGHT SAME PROBLEM EXISTS FOR HIM I THOUGHT THE SIDE VENT FOR RV TEN COULD BE INSTALLED ON BELLY OPPOSITE AIRFLOW DIRECTION WITH DETENT CABLE MIGHT WORK ANYONES THOUGHTS ON THIS IDEA

[CMW]

Here's a couple of pictures I took at Oshkosh last year of reversed NACA vents in the rear inspection covers on a -8. I have no idea if this does anything to slightly reduce the pressure in the tailcone, but I thought it was interesting.





-Chris

[mannanj]

Not sure this link still works, but down the page a bit there's a section on what this guy did for ventilation.

http://bidasst.bizland.com/heatvent.htm

[jriblet]

Jim
After some more flying I found that this buzz I get is related to the vents or the vents postion. Open the vent and it goes away. Could play a tune with it but bet an ipod would be better.

Jeff Riblet
RV-8
KPVG

[db8]

A buddy of mine ownes the RV-8 that is in the pictures (a few posts prior to this). He said the reverse naca vents didn't help, or if it did, it's not much (miniscule). Just thought I'd pass that on. Dave

[Chino Tom]

I flew up to Mojave on Saturday for AOPA's airport day with the rear seat
back removed and the 4" X 6" baggage bulkhead inspection cover removed.
I didn't notice any difference in vent or heater airflow. I did think I could
hear more wind noise (probably my imagination!). Still might cut a couple of
slots in the cover anyway.

[flickroll]

Originally Posted by Chino Tom

I flew up to Mojave on Saturday for AOPA's airport day with the rear seat
back removed and the 4" X 6" baggage bulkhead inspection cover removed.
I didn't notice any difference in vent or heater airflow. I did think I could
hear more wind noise (probably my imagination!). Still might cut a couple of
slots in the cover anyway.

Thanks for the reply Tom. That's what I was planning to do but never got to it last weekend. Don't know what to try next....not real comfortable drilling holes in the turtledeck....

[db8]

Since two of you have moved the rear seatback forward (our out) and it hasn't made a difference, I think it concludes there is enough of a gap on both sides (with the rear seat like it normally is) to not restrict any air flow? I would have thought with Paul's hatch open on the shelf, that might have "helped" the flow of air to the rear. When I get mine done (with the fan to "pull" the air from the front), I don't think I will seal off everything like first mentioned (except the big hole where the fan is pointed). That whole part of the project might have been a waste of time?

I guess the big question is if air is being drawn out through the leak holes in the empennage during flight? Or, because of air and pressure differentials, is air getting sucked in possibly (a little)? It would be interesting to put some yarn back there all over the place and a video camera that doesn't interfere with the elevator pushrod. Or, if any of you or your back seaters are cigar smokers, light up and see where the smoke goes?? Just some thoughts, but leave the cards on the ground ;-) Dave

[jthocker]

I've been a little skeptical watching this thread.
From my experience with my "open canopy" mod, I know that the rear of an RV8 canopy does not lift, it in fact presses down on the turtle deck.
I have a golf club mod, that allows the aft baggage bulkhead to lay down, and I flew that way last summer. I didn't think about seeing if I got more heat because, well, it was summer. I was disappointed when Paul verified that he got no increase in flow with the door open.
Since I built the golf club mod, I can easily open the rear compartment and check things in the aft fuselage area.
I found something directly attributable to another "mod", my smoke system!
The entire inside area of the fuselage "belly skin" was coated with smoke oil residue.
It had been entering from an unplugged "future Nav antenna" hole, just fwd. of the tail spring bolt hole and migrating forward.

I'm thinking the best fix for more heat in the rear of the RV8, is moving two things.
The first will be, to move my condition inspection gradually to January.
The second will be to move my hangar to Florida.

Good luck,