Hot Tunnels

rv6ejguy · #1 11-21-2005, 03:31 PM

Have any RV10 fliers come up with a cause or solution to the hot tunnel syndrome yet? I'm still building and would like to make any appropriate mods now rather than later.

brenthg · #2 11-22-2005, 05:11 AM

Quote:

Originally Posted by rv6ejguy

Have any RV10 fliers come up with a cause or solution to the hot tunnel syndrome yet? I'm still building and would like to make any appropriate mods now rather than later.

So far, the simplest solution is to connect the scat-tubes that are suppose to connect to the exhaust muffs and connect them directly to the cabin heat door assembly on the fire wall. This eliminates the cabin heat control, but it does cool the tunnel down to the point you can lay your hand on the tunnel and not burn your skin during flight. Now that cooler weather has arrived, the tunnel is even cooler. Not sure what to do for cabin heat if we needed it.

I think one of the problems in our early flight testing was excessive heat in the tunnel creating a serious vapor lock with the fuel being super heated in the fuel lines inside the tunnel. We actually insulated in and around the fuel lines and that helped tremendously.

Vans is certainly aware of this and has indicated that they are working on a solution.

Hope this helps.

vic syracuse · #3 11-22-2005, 08:24 AM

I thought I had poisted this already. My apologies. I THINK I have solved the hot tunnel problem in this manner. I took one of the fresh air tubes off of the back of the right rear baffles and added a "Y" to it. You can get them from A/C Spruce for $20. From the "Y" I went to the right hand heat muff, and then to the heat box on the firewall. I took the other tube off of the "Y" and pointed it right at both heater boxes. It seems to cool the tunnel down just fine, and the hot air from the rear seats is hot enough to heat the entire cabin. As a matter of fact, it's usually just cracked open just a little. These heat muffs put out way too much heat. I've tested it only as low as 20 degrees F.
The other heat muff is connected, but the hot air is dumped overboard. Vetterman tells me that we need airflow over the muffs.
For those who have easy access to the heat boxes, I would recommend installing an insulator (phenolic, silicone rubber, etc) between the heat box and the firewall. I'm sure that would help, as right now with them attached directly to the firewall, the whole firewall is getting hot because it is acting as a heatsink.

Vic

brenthg · #4 11-24-2005, 04:12 AM

Quote:

Originally Posted by vic syracuse

.....I would recommend installing an insulator (phenolic, silicone rubber, etc) between the heat box and the firewall. I'm sure that would help, as right now with them attached directly to the firewall, the whole firewall is getting hot because it is acting as a heatsink.

Vic

Has anyone actually insulated the firewall with flame resistant material? Just wondering what should be used to glue the insulation to the firewall. Vic...sounds like you're on to something here. We have actually even thought about adding some cowl vents in the lower cowling, near the mufflers, to draw out some of the heat.

What say you?

Brent

jrdalton · #5 11-24-2005, 12:06 PM

I'm not yet a -10 builder (starting 1.1.06) but why couldn't you just add a vent somewhere and run a cold-air tube right into the tunnel? I've seen this done for keeping the radio stack cool with a perforated tube.

glenmthompson · #6 11-24-2005, 03:30 PM

Quote:

Originally Posted by vic syracuse

I thought I had poisted this already. My apologies. I THINK I have solved the hot tunnel problem in this manner. I took one of the fresh air tubes off of the back of the right rear baffles and added a "Y" to it. You can get them from A/C Spruce for $20. From the "Y" I went to the right hand heat muff, and then to the heat box on the firewall. I took the other tube off of the "Y" and pointed it right at both heater boxes. It seems to cool the tunnel down just fine, and the hot air from the rear seats is hot enough to heat the entire cabin. As a matter of fact, it's usually just cracked open just a little. These heat muffs put out way too much heat. I've tested it only as low as 20 degrees F.
The other heat muff is connected, but the hot air is dumped overboard. Vetterman tells me that we need airflow over the muffs.
For those who have easy access to the heat boxes, I would recommend installing an insulator (phenolic, silicone rubber, etc) between the heat box and the firewall. I'm sure that would help, as right now with them attached directly to the firewall, the whole firewall is getting hot because it is acting as a heatsink.

Vic

Hey Vic, as I have said earlier, your idea of insulating the heat box, as it acts as a heat sink, is a very good idea, but fails in application. In 331JH, we hae completely disconnected BOTH heat exchangers, and have run BOTH fresh air inlets to the heat exchangers directly into the tunnel. This makes the tunnel IMHO ....JUST tolerable. Therefore, the idea of insulating the heat boxes as heat sinks is not the right direction, and IMHO is ill advised as phenolic will burn/coke rapidly in the event of a fire and burn throught the firewall in short order, and it will not affect anything as far as cooling any way.
Take this as fact guys, the heat entering the tunnel is a result of radiant heat from the firewall and the exhausted cooling engine gases (NOT combustion exhaust gases).
Lets think about this a minute gentlemen.. now,... go fly your 6, 7, etc with bare feet. Put your bare feet on the floor at cruise on a warm day. They will not be there very long. Now, this tunnel is directly over this hot area, with no outlet for the radiated heat. Does this all make sense now?
Now....How you prevent this heat from entering the tunnel, ie. insulation (which alone had no measurable effect on 331JH), venting, etc...Is where this conversation needs to go.
I think I, along with Jim have spent more time on this than any other 10 owners/mechanics, so I hope we can save time from not heading down blind alleys ie. insulating heat boxes, etc...
Glen

vic syracuse · #7 11-26-2005, 06:57 PM

Glen, there certainly seems to be something different about yours, as mine works as described. We just went to Kansas City and back, about 10 hours of flying, at altitudes up to 11K' and below freezing temps to 60 degree temps. The tunnel is OK now. We get all of the heat we need with the valves cracked about 1/8 to 1/4. Again, I have only 1 heater hose hooked up to the rear ducts from the right rear heat muff, and am blowing fresh air from the "Y" directly at the heat valves on the firewall. I am taking the air off of the right rear baffle.
I'm sorry you are having such a hard time. There must be something different between the 2 airplanes. Don't hesitate to call me and we'll see if we can figure it out together.

Vic

brenthg · #8 11-28-2005, 05:14 AM

Quote:

Originally Posted by vic syracuse

Glen, there certainly seems to be something different about yours, as mine works as described. We just went to Kansas City and back, about 10 hours of flying, at altitudes up to 11K' and below freezing temps to 60 degree temps. The tunnel is OK now. We get all of the heat we need with the valves cracked about 1/8 to 1/4. Again, I have only 1 heater hose hooked up to the rear ducts from the right rear heat muff, and am blowing fresh air from the "Y" directly at the heat valves on the firewall. I am taking the air off of the right rear baffle.
I'm sorry you are having such a hard time. There must be something different between the 2 airplanes. Don't hesitate to call me and we'll see if we can figure it out together.

Vic

Hello Vic,

Had to chime in here. 331JH is my Dad's -10. Glen and I helped build this wonderful flying machine. This -10 shouldn't be any different than yours...firewall forward was assembled per the plan. The next time you have the cowl off, send us some pictures.

We are considering adding a small hinged door in the bottom of the tunnel, aft of the front seats and controlling it with a push-pull cable...similar to a cowl flap. What do you think? We're still hoping Vans will come up with a solution.

Brent

vic syracuse · #9 11-28-2005, 08:34 AM

I'll try to get some pictures this week. Where do you live. Perhaps we could meet halfway?

Vic

brenthg · #10 11-28-2005, 11:06 AM

Quote:

Originally Posted by vic syracuse

I'll try to get some pictures this week. Where do you live. Perhaps we could meet halfway?

Vic

We're in West Palm Beach at a private airport community called Wellington Aero Club (FD38). Maybe someday when it's cold up there, you'll want to fly down here where it's warm.

Brent