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Yep, tunnel finally fixed. Should be an AD.

glenmthompson

Well Known Member
Well here is is, we finally did it. Proved what was causing, and found a fix. I was right all along, the fix is in preventing the heat from entering the tunnel through radiant/convective heat transfer through the firewall and belly skin.
Jim called me last night and said he had an idea of insulating the bottom with his super wombat mylar heat shield on the outside, to prevent the tunnel cooking, per my persistant whining and screaming.
So, poor Glen spent an hour degreasing the yet to be painted belly (primer for now) to allow the 18" heat shield to be applied with super duper carpet tape and my heavy duty al. duct tape.
***** Results, the tunnel on the flight we did today was just as cool as it was before we started the engine! My theory has been proven. Whew,... finally, no more screaming and IM's to tone it down.( not quite done screaming yet on this subject...read on)***********
This is what IMHO, yet more experienced than ANYBODY in this area on the RV 10, needs to be done to ALL 10's.:
.
@@@@@@ Install a stainless steel heat shield as suggested by an extremely intelligent 10 builder about ready to fly. Needs to be at least as wide as the tunnel, all the way back to the rear spar carry through. Stand it off, say, oh 1/8" or so, and add fiberfax as a further insulator.
............###Trivia here..Did you know that the abladable heat shield on the Apollo and Mercury spacecraft was mainly fiberfax? Yep.
@@@@@@ No fresh air is necessary in the tunnel after this is accomplished.
@@@@@@The firewall needs to be insulated very well ON THE ENGINE SIDE too, by the above mentioned mylar, SS shield or whatever you want,... the prevent heat introduction through the front is waht needs to be accomplished.
@@@@@@ Call Vans and tell them to [snipped by dr] pay attention to this thread. Listen...How does tis sond to you....? Insulate the inside of the tunnel and blast copius amounts of precious, drag inducing, engine life blood, fresh air, into the tunnel for cooling? Per their SB? Are they nuts? IMHO, nope, just maybe lazy, and not touching their tunnels inflight...Or possibly, some people, tired of Glen pointing out dangerous/annoying things about the RV 10.
@@@@@@ Demand Vans turn the above into an AD....Remember, this engine on N331JH has quit in me 3 times with the elec. fuel pump off due to vapor lock (read boiling fuel). And there has been at least one dead stick landing that many of us attribute to vapor lock....There have been AD's issued on certified A/C for far less. THIS IS AN UNDENIABLE, VERIFIABLE, FACTUAL, REALLY DOES CAUSE ENGINE FAILURE, NEED FOR AN AD!!!!
@@@@@@ Retrofit on flying or substantially completed 10's will be pretty easy. Say, a weekend's work.
@@@@@Scrubbing/cleaning the belly of exhaust stains will be a piece of cake with SS on the belly.
@@@@@ Further fire protection will be awarded to fragile fuel lines in the tunnel area in case of cowling fire.
.
Jim and I will be in the Vans tent at the predesignated 10:00 AM meeting time on 27 and 28 July.....Also, when you look at "The Monarch", please remember she is a flying testbed right now and, yes, we will wash it, finish interior work, and finish the Monarch's spots now that the tunnel problem has been identified and temporarily fixed.
Gawd, what a battle this has been...Good luck and if you treasure your unburned skin and fuel in a liquid state prior to the carb....., take heed.
Glen
 
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please explain

OK a lot in your post....please just the facts....are you saying you put a heat insulating material on the firewall engine side?
I am getting confused with the other heat shield....are you saying to put it on the outside on the belly in the airflow and stand it of 1/8?? :eek:

And thanks for all the work you have done.

any pictures

regards Chris 388 Melb AUS
 
yep...

Yup, you understand me correctly on both parts. The well deserved reason I have a lot of info, is due to the immense amount of mine and Jim's life that has gone into this @#$%$#@ issue.haha...And to 100% dispell the many nay sayers (Vans included BTW) to my observations and theories.
I hope this is the "hot" topic with Vans this OSH. It needs to be. This plane is sooo cool, and industry leading, "we" don't need this kind of problem out there when there are soon to be hundreds of 10's flying. Can you imagine how many potential future engine failures/scalded bodies there will be out there in a year or two? The mind wanders and does not like the possibilities.
Glen
 
PS to Brent.

Brent, can you take your comp. guru pic skills and get a pic of this before OSH? Maybe I can email one from my phone and you can post? Or anybody else with more patience than me to get the pics to take?
Glen
 
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Thank you for all of your work on this problem. Much appreciation for photos or sketches when they are available. I will try to find you on the 27th or 28th at Van's. I'll bet there will be quite a few people wanting to talk to you.
 
Glen, Great work work!!!!!!!, thanks for verifying the theory. Did the problem go away with just the mod to the belly or did you also do the firewall??? (Trying to determine whether or not to make the ff mod)

Deems
 
tempory fix??

I think what you have done is just great ......I wonder what can be done about under belly as having someting there wouldnt look the best (better than engine falure) and would cause drag with 1/8 off the belly. Did you try a shield over the rear part of the exhaust to help stop radiating onto belly.

Chris
 
Past suggestions.

Will respond to exactly what I would do personally when I have a few more minutes. I have though, explicitly said several times in the tunnel tips section about my suggested fixes, false floor, etc. If one cares to look there until I get a little bit of time to be very specific, it might be worth looking there in tunnel tips.
Glen...(breathing easier now.)
 
GREAT!!!!!!!

I also thank you for conquering this fire breathing dragon.

I will pass on the info R. E. the heat shield working.

But, now how are you going to cook breakfast on those morning flights??

Mike
 
Are any RV-10's flying with the Sam James cowling, and if so, are they having hot tunnel problems?
 
My personal opinions, and how this should be fixed. As in the final solution.

dmaib said:
Are any RV-10's flying with the Sam James cowling, and if so, are they having hot tunnel problems?
I am not aware of any SJ cowls flying in the 10, but lemme tell ya something. this tunnel is a closed area, and I believe that even without the "chin" CONCENTRATING HEAT UNDER THE TUNNEL,, there will be MORE than enough heat to fry eggs in there.
.
.
NOW FOR MY HIGHLY REQUESTED OPINION FOR IF I WERE BUILDING A 10 for myself......
**** The heat shield mentioned above IMHO would be the best, and I would try this, actually, before my previously mentioned internal false floor due to the following.....
##### The heat put into the aft seat tunnel area is immense due to the converging of the exhaust gasses out of both pipes about 5 feet aft, watching the "stains" I know this. We actually GREATLY reduced the fwd tunnel heat problem with extra cowl bottom "gills", this allowed more heat to escape the sides of the cowl, outside the chin area, away from the center, front tunnel area, but due to the converging of cooling and exhaust gasses in the vicinity of the aft tunnel area, well, this area needs great attention.
##### If one puts the "false floor" I previously thought viable, well, that will work great I am sure in the front, but will continue to burn your passengers in the back. The reason I lean now toward the "external" heat shield is due to the aft seat area. There is just NO ROOM under the elev. push tube to install a "false floor" like I proposed in the front. Therefor, one will need to keep the heat from ever getting on the inside of the bottom skin in the back seat tunnel area.
##### I hear rumblings about drag and asthetics in my SS bottom heat shield. Well, I would, I think, have a lip/edge formed in edge the SS, that allows the SS shield to step down the 1/8 to 1/4 inch one chooses ( thicker the better, 1/8 min.). I also think I would have the SS shield ceramic coated with some of that super wambat, fututistic heat reflective mirror like coatings. This can be retrofitted to ANY existing RV 10 for just a few hundred bucks, and installed on the bottom with flush pull rivits. I am open to suggestions as to how to dimple the bottom skin though, if the false floors are already installed and closed up. The dimpling seems to be the only hold up, or just use conventional rivits.
##### Now the firewall. This MUST BE INSULATED ON THE FWD SIDE!!! Jim' mylar healt blanket stuff, although arguably not the most fire resistant, does a WONDERFUL Job, and heck, if it were to ever burn in a cowling fire, there is not much mass there anyway. Weighs just ounces. Your choice obviously, but lemme tell ya something. If you are unable to put your bare feet on the firewall, ...THEN U WILL HAVE FWD TUNNEL HEAT ISSUES, no matter how you insulate the belly!!!! One thing to ponder huys... Every calorie of heat that enters (assumption for argument purposes my fellow engineers) the tunnel, be it from a leaking cabin heat valve pass through, or conducted or radiated heat through the firewall or belly, will raise the temp. in the tunnel. Up to and including the egg frying temp stage. Trust me. this has been my life the last 8 months. we have not finished the paint scheme on jim's plane due to this issue. If your spending 100K on this plane, you need to heed the above, and spend few hundred bucks on this mod. AD or not.
###### Worried about weight? Well then take off those **** heavy and expensive vetterman mufflers and install straight pipes like every other RV. Vetterman's is making them up now for Jim. He wants to get rid of that horribly heavy heat sink in his cowling that is EXTREMELY close to that sensitive fiberglass.
###### Now, for asthetics.... The dimensions ought to be about 14" wide in the front at the firewall to 8" wide in the back, carried all the way to the rear carry through spar area AT LEAST!!!!...A little further will only help aft seat heat problems! Now...nless your are one who scrubs the belly and waxes said same, every flight....well, come on, think about it. You will have actually with SS, a much easier to clean surface. Plus, if one chooses the super wombat shiny reflective heat reflecting coating, one can have a "mirror" on thieir belly! Not unlike many show cars! Sounds like a pretty cool plane to me!
@
@ BOTTOM LINE HERE ..KEEP THE HEAT ON THE OUTSIDE OF THE FIREWALL AND BELLY SKIN.............
Glen
 
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Cooking my eggs..

Mike S said:
GREAT!!!!!!!

I also thank you for conquering this fire breathing dragon.

I will pass on the info R. E. the heat shield working.

But, now how are you going to cook breakfast on those morning flights??

Mike
Well Mike, we can hook back up the cabin heat finally, and still have plenty to even cook our cake in an oven! The cabin heat works more than well enough for this.!
Glen
 
Woo Woo "AD"?

glenmthompson said:
@@@@@@ Demand Vans turn the above into an AD....Remember, this engine on N331JH has quit in me 3 times with the elec. fuel pump off due to vapor lock (read boiling fuel). And there has been at least one dead stick landing that many of us attribute to vapor lock....There have been AD's issued on certified A/C for far less. THIS IS AN UNDENIABLE, VERIFIABLE, FACTUAL, REALLY DOES CAUSE ENGINE FAILURE, NEED FOR AN AD!!!!@@@@@@

@ BOTTOM LINE HERE ..KEEP THE HEAT ON THE OUTSIDE OF THE FIREWALL AND BELLY SKIN.............GLEN
Glen your RV building and reputation are without question, but it seems you have a lot of emotion in this. Also I think the SS external sheet on the firewall and belly sound fine. It may indeed be the optimum solution.

I understand where you are coming from, but as you know these are experimental aircraft. "AD" is a dirty word to start with and does not apply to us at all. Some who don't know as much might misunderstand, so I just wanted to clarify that. I have not built or flown a RV-10, but I do have experience in with Van, heat transfer in airframes and an interest in all things RV and engineering. Your evaluation of keeping the heat OUT in the first place is a sound idea; that is what the space shuttle does with tiles.

As far as vapor lock and HOT floor......hummmm? Vapor lock is a safety issue. Glen, is HOT floor and vapor lock really related? I would say insulate all fuel lines, put a cooling shroud or and air blast on gascolater or fuel pump as needed. I am pretty sure an external SS sheet on the belly will not help fuel vapor lock, which is serious and should be addressed, but it's a separate issue, don't you think? Not sure how the SS firewall shield would improve vapor lock, but imagine it could if it also shields fuel lines from heat. Of course auto gas need not apply to RV-10's.

I think the Vapor Lock be looked at separately and seriously. Just an observation.
 
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I think the issue was that the fuel lines run through the tunnel, which is where the vapor lock is the issue. But I could be wrong... being a -7 guy myself.
 
That is hot

osxuser said:
I think the issue was that the fuel lines run through the tunnel, which is where the vapor lock is the issue. But I could be wrong... being a -7 guy myself.
Thanks, Vapor Lock does get my attention. I can see that than. From my research most vapor lock happens in the fuel mechanical pump and sometimes in the carb itself, fuel boils in the bowl. Of course lines are on the list, but I would think the ones in the engine compartment would be more critical than the tunnel? If the tunnel is that hot I would insulate and reroute the fuel lines. That is hot!
 
gmcjetpilot said:
Thanks, Vapor Lock does get my attention. I can see that than. From my research most vapor lock happens in the fuel mechanical pump and sometimes in the carb itself, fuel boils in the bowl. Of course lines are on the list, but I would think the ones in the engine compartment would be more critical than the tunnel? If the tunnel is that hot I would insulate and reroute the fuel lines. That is hot!
Ok, for the nay sayers, once again, lets rephrase..... imagine if you will, flying along. tunnel too hot to touch for even 3 seconds. Inside that tunnel are fuel lines, elec. fuel pump, fuel selector valve, FF transducer.... being cooked to oh I don't know, at least 120-140deg? Just as a guess. (Tunnel is MUCH hotter than these temps, but obviously the fuel does not have enough residence time in the tunnel to completely approach tunnel hand scalding temps.) Insulating lines will help, but like Vans says about blowing air into the tunnel, sorry, this is just a bandade for a much bigger wound. Any way, now take this super heated fuel, being sucked by the VERY HOT engine driven fuel pump, and with elec. pump off. Or God forbid elec. pump failure, or just plane failed to turn it on. Add now, line restrictions and gascolator restrictions, uphill sucking of fuel from wings, and you have, maybe several inches below atmospheric pressure worth of vacuum/suction. VAPOR LOCK HERE IS GUARANTEED! If this happens and the elec. pump is say, inop...Unles you are in the flight levels, you're gonna land off field. I guarantee it!.
Lets pose another question...Who wants to be burned, and burn their passengers virtually every flight? Ever fly in Fl or TX or AZ in the summer, with a huge radiating heater next to you?
Things that hurt people and could make planes crash are important to me and hopefully every other pilot and plane manufacturer. I have experienced 3 engine failures due to vapor lock with the elec. pump off in cruise. Once again,..................Lemme say it again..............I have experienced 3 engine failures due to vapor lock with the elec. pump off in cruise. And I am certain at least one RV 10 dead stick is attributed to this anomoly.....IMHO, an AD is justified. Vans can call it what they want, experimental people can call it what you want. Mandatory SB, ...doesnt matter.
Glen
 
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dmaib said:
Are any RV-10's flying with the Sam James cowling, and if so, are they having hot tunnel problems?

Not sure if Sammy James has any custom cowl parts for th -10 yet, but if he does, they'll work.

I happen to of had first hand experience working with Sammy James way back in the late 60's and early 70's when he was the race mechanic and test engineer for Bertram Yacht. He is a clever guy.

Sammy, if you read this, you know how many stories and lies I've told....I learned them all from you. :)

Brent
N331JH - The Monarch
 
I get it

glenmthompson said:
Ok, for the nay sayers, once again, lets rephrase..... imagine if you will, flying along. tunnel too hot to touch for even 3 seconds. Inside that tunnel are fuel lines, elec. fuel pump, fuel selector valve, FF transducer.... being cooked to oh I don't know, at least 120-140deg? Just as a guess. (Tunnel is MUCH hotter than these temps, but obviously the fuel does not have enough residence time in the tunnel to completely approach tunnel hand scalding temps.) Insulating lines will help, but like Vans says about blowing air into the tunnel, sorry, this is just a bandade for a much bigger wound. Any way, now take this super heated fuel, being sucked by the VERY HOT engine driven fuel pump, and with elec. pump off. Or God forbid elec. pump failure, or just plane failed to turn it on. Add now, line restrictions and gascolator restrictions, uphill sucking of fuel from wings, and you have, maybe several inches below atmospheric pressure worth of vacuum/suction. VAPOR LOCK HERE IS GUARANTEED! If this happens and the elec. pump is say, inop...Unles you are in the flight levels, you're gonna land off field. I guarantee it!.
Lets pose another question...Who wants to be burned, and burn their passengers virtually every flight? Ever fly in Fl or TX or AZ in the summer, with a huge radiating heater next to you?
Things that hurt people and could make planes crash are important to me and hopefully every other pilot and plane manufacturer. I have experienced 3 engine failures due to vapor lock with the elec. pump off in cruise. Once again,..................Lemme say it again..............I have experienced 3 engine failures due to vapor lock with the elec. pump off in cruise. And I am certain at least one RV 10 dead stick is attributed to this anomaly.....IMHO, an AD is justified. Vans can call it what they want, experimental people can call it what you want. Mandatory SB, ...doesn't matter.
Glen
Ok Glen thanks I get it, I did not know the fuel lines and fuel pump where there; clearly now that you explain it, the hot tunnel could contribute to vapor lock, but you don't have to be condescending about it.

You took this defensive attitude when you said your 3-blade MT prop was not slower than a hartzell a while back and chewed me a new one. I suggest that your highly modified, high HP, engine running at a higher MP, might make up some of the speed difference. I guess you owe me an apology, since it was also Van's conclusion, in a RVator article he wrote a month later, regarding the fly off he had with your plane Vs. the factory RV-10. His conclusion was your engine made the difference not the prop, which was slower than the hartzell by a significant amount. Sorry just our opinions and we are entitled.

Thanks for straightening me out about the hot tunnel, clearly you are right. I just though all those years in engineering school and study of heat transfer I could help. Sorry. I don't know how structural the tunnel is but I would cut large vent holes in it, but like I said I like your idea of keeping the heat out in the first place.

Good luck with your SS sheet solution and AD's. Van's pretty stubborn and will be pleasantly surprised if he makes your mod a standard feature. I hope your solution works and he does incorp it. You can't possibly call me names or chew me out for agreeing with you. Cheers George
 
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What fly off???

I never heard of any flyoff with the factory plane. I am also now the only one who flys Jims plane, and I have not flown off with any other 10.
Also I am on record many times in this forum, that we now have Jims plane actually faster than the factory lyc. powered plane!
And sorry Mr. George, but it gets pretty tireing to write countless times what the problem is, then have someone write here that I/we are clueless and don?t understand vapor lock, when the someone pointing their finger at us, does not have a clue as to the layout of the infamous tunnel. HHHHMMMM
Also,..... passionate about an airworthiness issue with Vans newest, most awsome plane to date???? OF COURSE!!!!!!
Glen.
 
Here you go

As far as the tunnel I have lost interest, good luck. You need to calm down. No one is pointing fingers. I believe you, there is a problem, got that and never doubted it. I made it clear that I was asking a question and did not know the routing of the fuel and pump. When someone puts "?" after a sentence, it's a question not a pointed finger.

Sounds like re-route of fuel lines and insulate the tunnel to keep the passengers from dying by combusting and catching on fire would do it; that's if your friends heat shield idea does not work as well as first thought, no offense. Geeeee, the RV-10 sounds like it sucks. Is that why you are so angry? We are just having a conversation; no need to attack me. If you don't like or agree that's fine just say you don't agree. It sounds like a workable problem to me, but again what do I know. I no longer care, but sincerily wish you the best luck. May be you should bring lawsuit against Van's, that's the ticket. He can always just raise the kit cost to pay for leagle fees. Or you could just modify your own RV-10 as you see fit and let everyone else decide how to solve the issue.

BTW: to answer you question, this fly off: (RVator flight test, "RV-10 Comparison", page 6, 5th issue 2005.)



*(N610RV posted a 198mph speed at 8280ft and 2251 lbs, -3 mph from spec, and 3.7mph to 5.1 mph slower than the factory N410RV. RV610RV used a standard Hartzell. The factory plane N410RV, uses a Hartzell BA prop. That would account for the +3 mph difference. The other plane, N64ME had a Hi-compression engine and should have been much faster. It was only 1 MPH faster than the factory RV-10 and was hindered by the 3-blade MT prop, which I (and Van) estimate cost at least 6 to 8 mph in speed verses the faster Hartzell BA prop. The customer built RV tested, N104ME was well over spec at 208.6 MPH!!!! That proves a 260HP/Hartzell BA prop RV-10 will do better than spec.)

I guess I got Vic and you mixed up, oh well. I truly regret trying to understand the problem and think I might be able to help.
 
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Keep thinking

Ok the problem is fixed but I do not want to put whatever external on the belly (I understand flying 10s need something now) so keep thinking guys and see if we can do something else there.

Aparently Vic Syracuse has also fixed the problem so am desperately trying to find out what he has done...will post.

Chris
 
Is it possible to exhange a section of the bottom skin with a stainless one built right into the airframe, then put insulation on the INSIDE and a false floor in the tunnel, also consider turning the exhaust tips down, it might help a little.
 
SS skin

I doubt that replacing a part of the skin would work, even if it was something that could be accomplished without a huge ammoount of work.

Stainless will conduct the heat into the passanger compt almost as well as aluminium-------think about cook ware-------------

The SS heat shield works beacuse of the air space between it and the fuse, and the air flow through that space.

Mike
 
Thanks Glen for finding the root cause of the heat , trying the Vans fix (unsuccessfully) and coming up with a flight proven fix.

For those non- 10 builders, the 10 uses a tall, structural tunnel running down the center of the forward fuselage to carry loads in lieu of upper longerons as on most other RVs. This is required because of the cutouts for the gullwing doors. Please don't punch this tunnel full of big holes! Not only might this compromise the integrity of the structure, it would only pass more heat into the cabin.

This tunnel contains almost the entire fuel system, brake lines, front and rear heater ducts, control rods etc. The fuel system is not easily moved to another location. Vapor lock and the potential for burns to the occupants have been documented on this forum by several RV10 fliers.

For those building 10s, serious consideration might be given to installing the fuel system components off the belly floor, a second false floor and insulation between them. Clearly, if you don't, you'll be forced to use a method similar to Glen's on the outside of the belly skin. Maybe not pretty, but proven functional and better than a dead stick landing.

Stainless has a fraction of the heat conduction of aluminum so this might help somewhat but think insulation as well.

Anyone else flying a solution, I want to hear about it.
 
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Service letter

I agree moving fuel lines is not practical. Here is the LS from vans.

http://www.myrv10.com/Plans/updates/RV10_Service_Bulletin_tunnel_temp.pdf

Here is one RV-10 builders compiled solutions on Van's site:

http://www.myrv10.com/tips/mods/HotTunnel/index.html

Apparently the brand of exhaust may have some effect (theory)? Also leaking cabin heat valves may add to the heat. If you have it insulated and cool air blowing in the insulated tunnel area I don't understand how that would not lower temp. Repeat I don't understand and make no claim to solve it, but apparently it happens and is difficult to remedy for some. Others don't have as much of an issue? The ideas above seem reasonable in addition to Glens suggestion.
 
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Hot Tunnel Fixes

Here are several photos we took of our modification to N331JH. Take note that the silver mylar insulation taped to the bottom of the fuselage is temporary and it proved our point that the exhaust running down along the centerline was the biggest heating problem in the tunnel. This is the same insulation used on the firewall, too. Glen Thompson's idea to rivet a SS sheet over this insulation is a lot easier fix for the already built -10's, and I'm sure new builders and maybe even Vans will come up with several other solutions, too.

BOTTOM OF COWL
Bottom_Cowl.jpg


BOTTOM OF FUSELAGE
Bottom_Fuselage.jpg


SIDE VIEW OF COWL VENTS
Side_Cowl.jpg
 
Thanks Brent!

Yep, since I am "stuck" down here in Rio till tomorrow AM when we will depart for MIA, then to OSH, I sure am glad Brent got those pics posted that Jim took. One can see the side gills I wrote about a while back, those are painted and faired in, as they were installed before I painted the plane for Jim.
Those "silver" somewhat larger gills on the bottom of the cowl, Jim made and I installed last week temporarily with the observerd pull rivits. One should note the uneven spacing on the rivits. There was alot of 3D going on there and I wanted the edges to be somewhat "down". BTW, Jim says he can make these gills on his CNC machine pretty easy and with any dimensions to suit your particular wants, needs, desires and necessities!
Write him @ [email protected].

Note the following please for those who have been unable/unwilling to thoroughly follow my tunnel threads before making condescending comments ( U know who U are):
########## The side gills made a SLIGHT", barely noticable difference in tunnel temps. In fact makes the fuselage side VERY hot.
######### Blowing one 2" scat tube of fresh air (Per Vans SB bandade) into the tunnel, cooled the tunnel sufficiently to touch the front, but still scald the paxs in the back.
#########Blowing 2 scat tubes (read NO CABIN HEAT NOW) cooled the front significantly, and made the back tunnel able to touch, but still VERY WARM.
Please note after this point, we have only ONE fresh air tube blowing into the tunnel!!!!!

######### The addition of the "silver" bottom gills, cooled the front tunnel significantly!...analysis......Tons of heat from engine cooling air and muffler heat leaves these gills and puts that heat out of the aft chin area and more to the sides, where we have an insulated cabin floor. As in, not below the stove, er, sorry, I mean tunnel.
######### Gills that then were added to the bottom skin in the aft tunnel area I think actually made the aft tunnel HOTTER, with the obvious entry of exhaust gasses at slower speeds.
######## NOW THE CREM DE LA CREM! We addded the above observed "insulation" to the belly, and the tunnel problem has been fixed!
We will be taking out all together, the fresh air blowing into the tunnel (remember the Vans bandade?) after OSH. Nope, tell ya what, we are gonna cover the hole before we leave for OSH tomorrow. Guaranteed not necessary now.


,
Now, to further explain my theories/observations...Listen guys, YOU MUST KEEP THE HEAT ON THE OUTSIDE OF THE PLANE!!!!! Don't like my SS suggestion? Cool, any ideas to "insulate" the bottom skin, as in, YOU MUST KEEP THE BOTTOM SKIN, AS IN THE BOTTOM SKIN, THE ONE THAT THE FUEL PUMP IS MOUNTED ON, COOL TO THE TOUCH. Sorry, but I guarantee you, if you have a hot bottom skin, you will have an RV "stove"
INSULATION INSIDE THE TUNNEL DOES NOT WORK! As in, install a " blanket" as we did last yaer, well before Vans suggested (per SB worthless bandade). Nope, nuh uh, does...not....work.....Any suggestions to such in any way, is a complete waste of time and weight. Insulate via a false floor? I think would work in an unfinished plane, but still will cause a scalding aft tunnel area problem, ...hence...My SS barrier/heat insulated heat shield recommendation.
Some kind of exterior barrier is required. period. Now, lets see some real ingenuity here! Put those RV minds to work!!!!!!!!
Glen
 
Bottom Heat Shield

Hey Glen,

Like I've been saying all along, it's always been the exhaust gas that's heated the tunnel, and maybe some additional heat from the firewall created by super-heated air in the cowl.

I believe you have the best possible re-engineered idea for the RV-10. Keep the heat out of the inside of the fuselage by fitting a heat shield to the bottom of the fuselage from the firewall to just aft of the passenger floorboards. Yeah, all you high powered aeronautical engineering types out there may have other ideas, but this is simple, common sense fly-by-the-seat-of-your-pants engineering that works. You can make it as complicated as you want, but simple works, too.

That's what NASA came up with to keep the Shuttle cool during re-entry. Makes sense, huh?

Brent - Son of N331JH
 
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We use stainless heat shields extensively in our turbo RV6A including on the belly skin aft of the exhaust pipe which only diverges from the skin by about 5 degrees. The skin does not get hot at all.

I've videotaped tufts all over our 6A in flight. The flow is highly turbulent behind the bottom cowl exit. I'm pretty certain an external heat shield would not cost any knots aft of this location. Easy to clean the belly too!
 
Sorry Brent,have to disagree...

brenthg said:
Hey Glen,

Like I've been saying all along, it's always been the exhaust gas that's heated the tunnel, and maybe some additional heat from the firewall created by super-heated air in the cowl.

I believe you have the best possible re-engineered idea for the RV-10. Keep the heat out of the inside of the fuselage by fitting a heat shield to the bottom of the fuselage from the firewall to just aft of the passenger floorboards. Yeah, all you high powered aeronautical engineering types out there may have other ideas, but this is simple, common sense fly-by-the-seat-of-your-pants engineering that works. You can make it as complicated as you want, but simple works, too.

That's what NASA came up with to keep the Shuttle cool during re-entry. Makes sense, huh?

Brent - Son of N331JH

Sorry Brent, but since the bottom cowl extra gills made a very significant difference in fwd tunnel temps, I believe you're incorrect in your assumption.
Unless you mean by exhaust gasses being the combined cooling AND combustion gasses. Engine cooling air is the major culprit. The noxious gasses only make things worse, & don't contribute significantly.
BTW, Jim is getting those straight pipes from Vettermans, and unless he turns them, oh say a foot either side of the chin, they also will make no significant difference. It all gets mixed up pretty rapidly down there.
Glen
 
Progress good

glenmthompson said:
Note the following please for those who have been unable/unwilling to thoroughly follow my tunnel threads before making condescending comments ( U know who U are):#########Blowing 2 scat tubes (read NO CABIN HEAT NOW) cooled the front significantly, and made the back tunnel able to touch, but still VERY WARM.Glen
Glen, there you go again.

I am glad you made progress.

I'll re post this link:
http://www.myrv10.com/tips/mods/HotTunnel/index.html


Don't you think the TWO huge heat muffs and the two leaky cabin heat valves on the firewall, routed through the tunnel may have something to do with the hot tunnel?

You say that this one change, removing the cabin heat SCAT and routing cool air made a large differnce in the front?

I am just saying...... Super hot air from dual heat muffs are heating the firewall valves and firewall (all metal no insulation), and super hot air is leaking past the cheap piano hinged valved dual cabin heat box's, even when they are closed. This is a big source of heat, IMHO.

Now you say you deleted the cabin heat and the back is still getting hot? Interesting.

If we could quantify the temp with temp gages it would help in analysis. "Hot enough to fry eggs" is not real scientific. I don't think the cowl exit air is that hot, but than again it can be measured.

You say venting cooling air in the tunnel does no good? May be you need a way for the cooling air to get out of the tunnel? Just saying. If you have a sealed tunnel and the pressure is higher in the tunnel than the air you THINK you are pumping there is no flow. It could be you need a cabin exit air, like a reverse belly scoop. Look at Bonanzas, they have ways for air to exit. Just saying don't kill the messenger. The exit is critical.

May be the air flow not only is stagnated in the tunnel but it's stagnated thru the cabin. I mean you are doing almost 200 MPH at 8,000 feet and you can't get enough cooling air to cool the tunnel? In engineering school and HVAC (heating ventilation and air conditioning) there are 3 qualities that define comfort: temp, humidity and circulation. I think you need some engineering.

And if it exhaust gas impinging on the belly there are ways to fix that as well, like guide vane's or vortex generator's (VG's) to excite the boundary layer to keep the exhaust off the belly. A big piece of SS would be nice to avoid.

I am not knocking your external heat blanket or shield, but how many plane have you seen like this? (No offense but the space shuttle is a differnt deal. Why don't other RV's have floors so hot to hurt the occupants? I am just asking; again don't shoot the messenger. In my experience both in engineering and airline flying the best solutions come from bringing in more ideas not isolating yourself.

Glen last, please stop with the personal comments, they're a waste of time. I'm trying to help you Glen. If I miss one of your points and you have to repeat, sorry. I assume you're open to other idea's? And if you don't agree, I assume you'll be a gentleman and just say you don't agree with out attacking, right. Thanks
 
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Been real ladies and gentlemen.

I've exhausted myself proving how to fix this problem.
BTW...ALL RV'S have hot floors that are not insulated. Bar none.(Ok, well, 6', 7's, 8', 9's, 10's.... Even Vetterman has an 8 and is interested in our studies. Says his is melting his shoes! Hmm, no other planes have heat shields on the bottom????...hmm, RV6eguy has one, Many glasairs have them. The SR 22 has them. Jim's old 6 had tons of insulation due to my melted sneakers. Maybe a doubter such as george would like to pick an RV... pretty much ANY RV except a 4, and fly with them in their plane with his bare feet placed squarely on the floor, oh say not for long, say 20 minutes, and then I'll be nice and help him a good skin graft surgeon!
Ya know, I said I would not bring myself to this, but I unfortunatelly have, yet once again. I found myself signing off once again to a "fellow" RV'r, yes, you George. And will bid farewell, yep, done with you yet once again, my mistake. First time shame on you, second time, shame on me... No need to PM me Doug, I am slapping my own wrist and signing off.
Any objective individuals who would like to continue this discussion in the PM realm, I would enjoy that immensly. Right now I am going to enjoy OSH, and sign off of my own thread. Good luck to all in fixing their RV ovens, and I hope George can find the right solution since, I am apparently clueless, and pretty much always going in the wrong direction.
Thanks to all those ( dozens and dozens) who corresponded with me on this, please continue to do so to my email, or PM... [email protected].
Dr. GMC, . Good day sir, yet once again, and for the last time. Good day sir.
(One parting request. Might you post your seniority number if you fly for my company, (we fly really shiny unpainted planes) so that I may forever put you on my do not pair with list....Airline guys will know what this means)
Glen
 
Hope it gets better for you

glenmthompson said:
I found myself signing off once again to a "fellow" RV'r, yes, you George. And will bid farewell, yep, done with you yet once again, my mistake. First time shame on you, second time, shame on me... No need to PM me Doug, I am slapping my own wrist and signing off. Good luck to all in fixing their RV ovens, and I hope George can find the right solution since, I am apparently clueless, and pretty much always going in the wrong direction. Dr. GMC, . Good day sir, yet once again, and for the last time. Good day sir. Glen
You sound like you have a personal problem with me. No one said you where clueless, that is all you Glen. In fact, in my first post, I said it sounded like a great idea. Hope your life gets better and you can be happy again. I was hoping you could teach me, but you are like a soaring eagle and obviously can't bother to fly with turkeys :D ; Clearly there's only one solution in your mind, yours. Which is fine. The solution has been found and that is that, end of discussion. Problem solved. Enjoy Oshkosh. Cheers
 
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Enough is enough

Ok gentlemen, you have subjected the forum to enough of your immature spitting contest.

Any additional posts to this thread from glenmthompson or gmcjetpilot in a similar vein will be deleted by this moderator.
 
I'll go one further, Sam (and thanks as always for your help - I was at OSH and had limited access to the web).

George M., be on notice that any posts by you from this point further in my forums that are not COMPLETELY CIVIL and within the posted rules will result in your being banned.

I'm posting it here in this public spot so you'll know it came straight from me.

The forum rules can be found at http://www.vansairforce.net/rules.htm.

No need for anybody to reply to this.

Doug Reeves (forum owner)
 
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OOps, sorry.

I must apologize to all for recent indescretions.
I also would like to say that my inbox filled up while at OSH, and it appears many have tried to PM me. My box is empty now and I would greatly enjoy sharing via PM a very promising brush/roll/spray on really cool heat barrier I found at OSH for the purposes of heat rejection, re. this thread. It is used to protect areas prone to even higher temps than we are seeing in our tunnels. Even up to 500 deg F!.
PS, ....AVG TAS to and from OSH was 204 MPH, 13.2 GPH. MPG was right at 12 NM/gal.(excluding taxi and take off fuel)..I say this to motivate yuz all as you pound rivets and fill pinholes.
I also would love to speak more with the MANY 10'rs I met @ OSH..Call me at 561-670-6095.
Glen
 
Hey Glen,

What do you think about working up a story on this and we'll put it in the 'Mod' section of VansAirForce.net - pictures and all.

All the best,
Doug
 
Second flight today in N710RV. Checked the forward tunnel area for high temps. Used the bare leg method. Stuck my bare left leg up against the tunnel wall and held it there for at least five minutes. No problem, even confirmed after landing that I still had hair on my leg (just in case my 33 month build had killed the nerves in the leg and I didn't feel the heat).

After hearing all the tunnel heat issues raised in the posts I did the following:

1. Bought a roll of engine gasket material at NAPA and cut out gaskets to install between the firewall and the heat vent boxes. (Don't remember for sure but I think this tip came from Tim Olson as 90% of the my help tips have - Thanks Tim).

2. Installed an RTV gasket around the inside of the heat vent doors after install by beading the RVT around the opening, placing a piece of wax paper over the RTV and closing the door with the cable. After setup of the RTV I removed the wax paper and re-closed the door. (Install tip from Jesse Saint - Thanks Jesse).

3. RTV'ed around the outside of each heat vent box.

4. Installed foil faced insulation on the bottom of the tunnel floor and over the inside of the firewall (used this method on my RV-6A firewall after it was built and it made a huge difference). I did not build a false floor in the tunnel, only put the insulation up to the edge of the fuel flow transducer and fuel pump.

5. Installed sound proofing foam insulation under the floor and on the sidewalls.

Hope these tips help.

By the way N710RV flies like a dream. Working on wheel pants and gear leg fairings between flights.
 
Brush on heat barrier

Glen so do tell whats the brush on heat barrier....website or any details would be great!

Chris :)

40388 Melb Aus
 
Congrats Russ!

I am soooo happy 4 U! Awsome plane huh!? For me and others, please feel the aft tunnel area next flight! If you have our problem, it will be OBVIOUSLY apparent, immediatly. ...If your aft tunnel is cool, especially if it is not insulated, well call me very confused.
Glen
PS. Thanks for the response Doug, I would love to do that mod article. Let me see first how this heat barrier coating works. It may be a God send....Lemme see!
 
Short exhaust stacks?

Glen,

Wandering around OSH and looking at the RV-10's it appears that the exhaust stacks on the Monarch are 2-3 " shorter than on other RV-10's. Seem's like this could account for why some have experienced the problem and others have not. Perhaps Van's/Vetterman made a subtle change in their production????

Deems
 
Stack length on Vetterman exhausts

Last year at the LOE flyin I recommended to Larry that a little more length on the exhaust stacks would keep the beely much cleaner, and most likely help with noise and heat. Larry sent a couple, I tired them, and as far as I know all of the subsequent exhausts are being shipped with the longer stacks. I felt I had the majority of the tunnel heat issue fixed prior to the longer stacks.

Vic
 
Info please

Vic, please give us a rundown on what you did to control the tunnel heat issue------what worked, and what didn't.

Thanks, Mike
 
Tunnel heat

Mike, I think I've posted this a number of times, so you can probably do a search and find it. But, in a nut shell:
I'm only using one of the heat ducts to the firewall from the right hand heat muff. I dump pthe heat overboard from the left heat muff. THe heat is so hot that we have found that one source of heat to the rear seats is adequate for the entire cabin. Then, I put a "y" tube in the duct off of the right rear engine baffle. One of the outlets goes to the right heat muff, and the other outlet has a duct that is pointed right at the firewall where the heat control boxes are. I insulated the firewall on the cabin side with 1/2" supersound proofing foam. I insulated the inside of the tunnel with 1/4" soundproofing foam, and stuffed some fiberglass batting in against the firewall side.
My wife reads the list, too, and on the way to OSH she was putting her hands all over the tunnel. I asked her what she was doing and she said she was trying to understand the tunnel heat issue. We don't have it.
In flight, my CHT's are 340-360, and max climb to 14000 feet on the way home yesterday showed 386 as the highest CHT.
Hope this helps.

Vic
 
Vic's plane..

Leeme tell ya boys and girls, as anal as I have been told I am, I did a once over on Vic's plane at OSH, and I must say....wow...wow...wow...nuff said. I hope alot more people get to see this shining sample of RV-10ism!
I will say too, that IMHO, the insulation inside thing is one that would not work, but if Vic insulated the inside the inside of his tunnel with as much enthusiasm and quality as the rest of his plane, I'll bet he effectively hermitically sealed the entire tunnel from the inside out!!! My hat is of to you Vic!
One question though I forgot to ask at OSH. Have you done the "hand test" on the aft tunnel area from top to bottom?
Glen
 
I really wonder if it is the insulation or...keeping airflow through the muffler heat muffs.

1. These mufflers will overheat if there is not a constant stream of air.

2. Once they get hot, they would radiate a ton of heat.

So, my theory is that those who disconect the flow from the mufflers entirely, simply allow the muffler heat muff assembly to heat soak and radiate a ton of heat.

On the other hand it sounds like those who keep air flowing through them are keeping cool.

Just a thought from a future 10 dreamer.
 
Glenn, first my SINCEREST thanks for your kind words regarding our airplane. The many long nights and lost week ends and holidays all melted into the past upon hearing all of the comments at OSH, :)
Next maybe I wasn't clear regarding the tunnel heat.... my wife was doing the hand test all over the tunnel. I've done it, too, and I assure you I feel it is fixed. I certainly haven't had any vapor lock or fuel flow issues in 300+ hours, and I've flown every where from the surface at 98 F to 18K feet. On the way back we did a sustained climb to 14000 feet. No heat issues. You mention the aft tunnel which I don't understand. That only gets hot when we turn on the aft heat, which is to be expected.
As I mentioned, I am less than 2 hours away from you. You are welcome to bring yours up, fly mine, and we can probably figure out yours.
There seem to be enough 10's flying that perhaps this Fall we could have a gathering of 10's at my place if there is enough interest.

Vic
 
Thanks

Vic, thanks for the reply---------yes, I do remember seeing your prior posts, I was asking more for all the folks out there in e-land who are looking at this issue/thread. Take a look at how many times this thread has been viewed.

Mike
 
Heat barrier info...

In the interest in keeping this important blog alive, and to follow up I have the following.............
***** Jim has a fuel leak that is taking our precious little time, so we have not experimented with the brushable heat barrier I reported I found @ OSH.
*****If yall wanna call the guy, he does ceramic, heat rejecting, corrosion, etc. coatings. His name is Tim Frater. Company name...Synergy Coatings....Neenah, Wi..............Website
WWW.coatings.LEWinc.org
.........Phone[/url] # 920-729-9939
I believe the brushable coating is called SP-303.
*****Great down to earth guys who had a tent in the Fly market. I told them to be ready for an onslought of RV'rs who wanna cool their floors/tunnels/ceramic coat...etc. Call em. I will get with Jim when we have a few minutes and do a little test of our own.
*****Thinking about this stuff, IF IT WORKS as claimed...Might be a great idea to coat the outside skin, as well as the inside skin/tunnel area.
****One thought. ... for those thinking of just possibly using this coating (if it works as advertised) on the inside of the tunnel..I want all to consider the LARGE amount of heat that will be convected/conducted up through the vertical sides of the tunnel... It appears Vic does not have this problem though, and he has only insulated the inside of his tunnel..Just food 4 thought.
Glen
 
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