Van's Air Force
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Vans Cowl Louvers
- Thread starter dvalle
- Start date
BH1166
Well Known Member
Dan, I installed on my 6a. I didn’t notice any change in what I was chasing. Didn’t hurt, cheap, no painting involved. They don’t come into sight unless you look for them. EXPERIMENT !
Louavul
Well Known Member
I added them to my RV-7, I believe they provided some cooling and prevented summer boiling fuel issues during taxi here in the high mountain of NM. If I were to do it again I'd follow Larry's installation, I really like the option of closing them off in the cold months vs speed tape.
wirejock
Well Known Member
Louver gates
I didn't plan on adjusting louvers in flight and didn't want the weight to add adjustable cowl flaps. The few I asked said they never close them unless it's very cold.
They are a few layers fiberglass and carbon fiber. They are slotted so they slide along the screws. The nutplates are in the louvers inside. If you look really close, you can see #40 index holes in the smallest hole. The process is simple. Loosen the screws. Stick a pick in the index hole and side the gate fore or aft. They will move from fully open to fully closed. Tighten the screws and they are locked in position.
I didn't plan on adjusting louvers in flight and didn't want the weight to add adjustable cowl flaps. The few I asked said they never close them unless it's very cold.
They are a few layers fiberglass and carbon fiber. They are slotted so they slide along the screws. The nutplates are in the louvers inside. If you look really close, you can see #40 index holes in the smallest hole. The process is simple. Loosen the screws. Stick a pick in the index hole and side the gate fore or aft. They will move from fully open to fully closed. Tighten the screws and they are locked in position.
I have them in my RV-9A that is in Phase 1 right now. They came with the finish kit as Vans deemed them needed with the new style nose gear. They are easy to install and not noticeable from the ground unless you look from below.
On first flight my cht’s went above 400 degrees on climb out. Lowering the nose and climbs at 110kts or higher lowered the max temps. I bet without those lower louvers cht’s would be very hard to control on climb.
On first flight my cht’s went above 400 degrees on climb out. Lowering the nose and climbs at 110kts or higher lowered the max temps. I bet without those lower louvers cht’s would be very hard to control on climb.
Thanks to all of you. I too am hesitant to install them thinking about the reduction in CHT's. I've had several planes, T210M, T210N and Baron all have cowl flaps and it's clear on hot days leaving them open reduces the CHT's. Guessing that the RV's can use a bit more opening than is provided by the cowl opening by the exhaust pipes. I'd like to say they have data but
I was planning them just like Larrys I just was concerned about cutting the openings in my perfect white cowling and what kind of a mess I would make. Looks like I'll just go for it...and slot them like Larry did
Thanks again
Dan
I was planning them just like Larrys I just was concerned about cutting the openings in my perfect white cowling and what kind of a mess I would make. Looks like I'll just go for it...and slot them like Larry did
Thanks again
Dan
Southern Pete
Well Known Member
I installed them on a 6, dropped the CHTs by 40* and the oil temp by 20*.
Easy to install, almost no draw backs.
Easy to install, almost no draw backs.
Carl Froehlich
Well Known Member
By chance did you take before and after speed data as a way to quantify the impact of increasing engine cooling drag?
Carl
Based on the before and after flight testing that was done when they were installed on the prototype RV-9A, I would say that your large temp changes are the result of other factors. There is no way installation of the louvers caused that much actual change. Not posting this to attack you personally, but I don't want anyone to be overly optimistic about the improvement the louvers can provide.
Is it possible you are talking about having installed the aftermarket cowl flaps, and not the slotted louvers?
I have them installed on my fixed pitch 180 HP RV-6A and I got the same result that was noted during the testing of the RV-9A prototype.
A slight reduction (7-9 degrees F.) of CHT's and no measurable speed difference at cruise power settings.
See above
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I know Southern Pete's aeroplane, he had higher CHTs than he really wanted on his 6A over several years since rebuilding the engine, regularly approaching 400*F even in UK conditions and 190*F + oil temperatures. After concentrating on the baffling he then installed the Avery louvres. His temps fell as mentioned. I believe there was little change in speed. He told me he thought the nose gear was choking the exit air and was surprised by the drop in temperatures.
Hi Scott
Thanks for sharing.
In all my years of experience in owning many planes, flying more, being an AP/IA and my job as an engineer...I'd agree with you without being involved with any of your work, hence the reason I was asking for input. I too wouldn't question someone posting facts on their experience. My entire career was very seriously data driven, many times, no room for error. And, for much of this, I did a LOT of flow modeling/testing which can easily relate to this, followed by actual hard testing both in the lab (usually dynos) and correlated track or field (for verification). Then the loop back to make corrections to the model....
Over the years and with the advent of good engine temp data for small aircraft, I've experienced gathering heat data on many planes, taking into account, altitude, OAT, fuel flow, etc. Unfortunately, sample size and controls were NOT adequate to publish. In my career work, I was responsible to try to assure all factors were considered for testing so as to create lab testing that would be representative when accelerated...which, at times, was very difficult.
Some of you might have read some of my articles where many times I question those that make people believe they are "experts" when it's only their opinion. I am sure, they do not have adequate hard data to prove statistically what they claim.
After 47 years of owning big bore Continental engines/cylinders, working on hundreds and reading about them nearly weekly over all those years...I have a signature line some might have seen or appreciate
Only one thing worse than a big bore Continental....2 of them!
Thanks for sharing.
In all my years of experience in owning many planes, flying more, being an AP/IA and my job as an engineer...I'd agree with you without being involved with any of your work, hence the reason I was asking for input. I too wouldn't question someone posting facts on their experience. My entire career was very seriously data driven, many times, no room for error. And, for much of this, I did a LOT of flow modeling/testing which can easily relate to this, followed by actual hard testing both in the lab (usually dynos) and correlated track or field (for verification). Then the loop back to make corrections to the model....
Over the years and with the advent of good engine temp data for small aircraft, I've experienced gathering heat data on many planes, taking into account, altitude, OAT, fuel flow, etc. Unfortunately, sample size and controls were NOT adequate to publish. In my career work, I was responsible to try to assure all factors were considered for testing so as to create lab testing that would be representative when accelerated...which, at times, was very difficult.
Some of you might have read some of my articles where many times I question those that make people believe they are "experts" when it's only their opinion. I am sure, they do not have adequate hard data to prove statistically what they claim.
After 47 years of owning big bore Continental engines/cylinders, working on hundreds and reading about them nearly weekly over all those years...I have a signature line some might have seen or appreciate
Only one thing worse than a big bore Continental....2 of them!
StephenC
Active Member
I fitted them on my 6 and they worked for me. I was having trouble with climb CHTs topping out at 438F so had to look at something. I was reasonably scientific with the way I progressed through the improvements so am confident about what I found. The louvers in my case made a 20F drop to my temperatures. The improvement that made the least improvement, that is I didn’t see any difference, was blocking all the holes in what were reasonably tight baffles. I made no changes to mixture or carb jetting. I did put a curved exit at the base of the cowl which made a good 10F difference. I now rarely see climb CHTs over 400F generally settling around 395F except on a hot day when I might get 402 or 3 . Cruise CHTs are around 330F.
Just my experience for what it’s worth.
Just my experience for what it’s worth.
BH1166
Well Known Member
You can tweak and build forever….. your plane is flying !
haha very true but it's tough to take the plane down for mods instead of just flying!
Mike Smith
Member
Which lovers?
I’m having cooling issues on my RV-6, I’m making progress with baffle mods and closing gaps in the baffles, but it’s still not enough. Which lovers (specifically) did you install? It sounds like that might put me where I need to be with cooling.
Thanks,
Mike
RV-6
O-320 with 10:1 pistons and dyno’d at 193hp
Northern California
I’m having cooling issues on my RV-6, I’m making progress with baffle mods and closing gaps in the baffles, but it’s still not enough. Which lovers (specifically) did you install? It sounds like that might put me where I need to be with cooling.
Thanks,
Mike
RV-6
O-320 with 10:1 pistons and dyno’d at 193hp
Northern California
Hello
Yes i have Louvers Installed in my RV9 Cowling, and yes it helps definitly in Clipbereichen and Cruise…… a Little bit too much in longer descends….Bit this is the smaler Problem i think
I will Show a few pictures the next das how i have it done….. whitout painting on the Cowling…..
Once I swapped to a constant speed prop ( and higher rpm) I noticed much higher chts on climb out. 420 was the norm. Cylinder 1 and 3 were higher. I cut the slot in the rear #3 baffle and that brought #3 down some, the removed the vertical deflector in front of #1 which brought #1 cht down w/o hurting #3.
I sealed up all the baffles, and contemplated the louvers. But the fall/winter temps cooled down so no issue for now. But I did fly with my nose gear cowl fairing off (exposing long ventral slot on bottom of cowl for 3 bladed prop) and noticed this extra airflow really brought temp down. Just a data point that my cooling is outlet flow dependent.
I sealed up all the baffles, and contemplated the louvers. But the fall/winter temps cooled down so no issue for now. But I did fly with my nose gear cowl fairing off (exposing long ventral slot on bottom of cowl for 3 bladed prop) and noticed this extra airflow really brought temp down. Just a data point that my cooling is outlet flow dependent.
