AX-O's Fastback RV-4

[pierre smith]

Another one.

Outstanding, Axel. Last month, my buddy, John Brooker, in Sandersville, Ga. flew his fastback-3 as well.

Best

 

[ppilotmike]

Nicely done!

Nine years of devotion has turned out a winner.

 

[TS Flightlines]

Congrats Axel on a job well done! Enjoy the fruits of your hard work.
Tom

 

[longranger]

Congrats Axel! I hope I can get to see her before I ship out to the Midwest. If not, I'm sure we'll cross paths again someday.

BTW, glad to see you ditched the flip flops for the flight!

 

[GLPalinkas]

Big time CONGRATS Ax....
Keep us posted on phase 1 testing.

 

[AX-O]

All,
Thank you for the kind words. The plan is to continue this thread documenting issues and fixed found during phase I. Like the high temps. I have along ways before it is an optimized machine.

I would like to say thank you to everyone that has helped me along and made it possible.

But must importantly my wife deserves as much credit. She has been supportive from day one. And it would have not been possible without her.

Now back to building. Oh wait. Flying!

Like Rosie would say, get back to pounding rivets.

 

[acroflyrgirl]

Nice work AC

Great job AC. Best Selfie ever of you both. Looking forward to flying with you.

 

[sblack]

Axel I just read through your entire thread. We are all so fortunate that you took the time to document your build. This will be an important reference for years to come. Thank you thank you thank you!

 

[southtarnation]

AC - gotta know, what did she weight out at?

Congrats! Thanks for the thread and the questions you answered for me too.

I guess the other fb builders and I are pretty interested in how light you got her to come out after your efforts put in.

 

[AX-O]

status

some of you have contacted me regarding the progress of my plane. I have not been able to dedicate any time to it in almost a month. The plan is to re-engage this coming up weekend.

Prior to my time-out, I was dealing with high temp issues and started making progress. I got the CHTs to be manageable but my oil temps are still way too high.

I started with the usual suspects
1. made sure the baffles were nice and no leaks
2. made sure the plenum was sealed. I made a seal out of RTV that fits perfectly now
3. verified that the Vernatherm was working
4. put the jumper on both of my Pmags from the beginning
5. added 2 more qts of oil to run with a total of 8 qts
6. did a bunch of research to see how much heat needs to be dissipated by a stroker 340. Was unsuccessful. I think the standard vans cooler is not big enough for my particular set up.
7. calculated my air mass flow based on my intake and exit areas. On the last flight I opened up the exit area from 26 to 36 in^2. That made the biggest difference in dropping the CHTs.
8. put the wheel pants on

The next step is to replace the inlet rings sized for a 320 (22.1 in^2 total) to a custom one made by Dayton Murdock (25.1 in^2 total, a 14% increase in area). Also to make piece of metal that will smooth out the airflow exiting the cowling/firewall (i.e. like the RV-8). Will let you guys know how it goes after I get back flying.

Below are 2 pics of the belly after flight 1. The airflow patterns are crazy. I have an idea on how to fix it. Will tackle it once the temps are under control.

This is the exit area before

and after. Once the temps are working, I will start closing the exit area again.

 

[AltonD]

Axel, make sure the oil cooler inlet line is on the bottom and the outlet is on the top for a vertical mounted oil cooler.

By circumstance I will not discuss, I know my oil temps run substantially hotter when I have 8 quarts on an IO360 (might have been a tad more).

 

[AX-O]

Wanted to give you guys feedback on Phase I. DanH, I have not mapped the pressures yet. Trying to get her flying and not be completely consumed with temp monitoring.

It has been a slow process. I have been fighting temp problems and trying to find the right prop pitch. The plane currently has about 8 hours on it. There has been a lot of fly, fix, fly going on. And some major mods too.

The plane handles nice although the controls feel a little heavier than my previous airplane. The plane stalls similar to the standard 4 however, it is stalling about 2 kts faster than my previous plane. It could be a difference in IAS caused by errors or the fact that I have been flying without the aft wing root fairings until I get the flaps/ailerons where I want them. It has a lightly heavy left wing.

In a solo configuration, the elevator counter weight is about 3/4 of an inch lower than the horizontal stab. At some point in the future I will take the shim out under the horizontal stab and make another tail fairing (so much work).

Now for some mods:
I have tried 2 different oil coolers. The first one was so subpar that I did not know how hi the oil temps would go (standard vans 7 row). It was place behind #4 at a 30 degree slant.

The second oil cooler did better but temps were still too high. It is a SW 8432R 8 ROW DUAL PASS. It was also installed at a 30 deg slant behind #4. It would hold around 225 deg but not with full power because my engine would reach 2700 rpms way too soon.

Being that I did not have the space for a larger cooler I started looking for different approaches and figuring out how to clean the airflow and make it work more efficiently. The biggest limitation is that I have to place the oil cooler low due to the upper cowling. That causes the oil cooler to get blocked by the Cylinder fins. So I came up with this approach. Maximize the airflow by completely cutting the aft baffle/plenum, raising the plenum by approximately half inch and mounting the cooler at 85 deg slant behind #4.

Picture below show mod:

Figuring out how close the plenum was to the cowl. Clay layed on to of plenum then both cowlings put on the aircraft.

Aft baffle and plenum flange cut.

Inner air dam to ensure air was not being sucked out of the oil cooler as airflow went down the cylinder fins.

Molding the new plenum.

 

[Mike S]

Ahaaaaaaaa been wondering how things were going.

A thought for you--------in the photos above about cutting the cowl exit------have you thought about putting a hinge on the part you cut out, and making it into a cowl flap that can be opened for climb, closed for cruise???

A quick flight with the aft wing fairings on would let you know if the sluggish handling and heavy wing are due to flying without them...........or is this a part that is not readily removable when installed???

 

[AX-O]

Cont. Sorry Mike.

After this mod the oils temps went down and I was able to find the top of the temps in cruise (2700 rpm due to prop). CHTs stabilized at 360s and oil temp at 217 deg. Huge improvement.

and completed. I used the plenum to give the structure the strength and stability I took away by cutting the aft flanges. The small indentation on top of the plenum bump also helps with bending.

From the first flight I knew that the exit air was misbehaving (due to oil trails after the flight). The air flow is turbulent and recirculating above the exhaust turndown. The next step will be to make a metal fairing that will extend from the firewall around the bottom landing gear tube to mitigate the almost 90 deg turn the air needs to make to exit the cowl. So I was thinking..... How could I quickly and representatively be able to make a "fairing" without drilling and spending a lot of time. Some type of proof of concept. Then It came to me. Aluminum tape!!!! So in approximately 30 minutes I wrapped aluminum tape from the tube to the bottom of the firewall. I use two layers of tape at 90 deg. I don't have that great of pics. Look in between the exhaust pipes. BTW, oil on the first pic is for airflow visualization after flight.

Results: Although OATs at 8000 DA were 2 deg warmer than previous data collected, the oil temps went from stable at 217deg f to stable at 209 deg f. The crude test worked! OMG, 8 deg cooler (everything else almost constant) just because some tape. I did not even wrap tape from the top of the firewall to the tube. So that will be the next thing I attack. A nice exit fairing. I will also figure out a way to redirect the exit air so it does not exit via the landing gear fairing. I will use left over engine rubber baffles.

 

[AX-O]

Prop:

I have tried 3 different props. Each one is better than the previous one but we have not found the right one yet. Craig is making another test prop. He is changing to a narrower cord and going with a 70X78. The 340 is making good power. But it is also presenting new issues that I have not experienced with my previous plane. For example, after 2 hrs of flight time I changed the prop for more pitch. Pics below show what I found. The torque must have backed off.

I talked to Craig and he said "she is definitely talking to you. It is not bad but here is how you fix it". He sent Nicole over to grab these cone shaped washers. I forgot the name of them. Put 4 of these back to back on each bolt and also a regular washer. Kind of like take 2 of these and call me in the morning. I had to order longer bolts so I call Saber (as always, extremely great customer support).

I could not find anywhere if it is bolt : 4 cone washers : standard washer or bolt : standard washer : 4 cone washers. I decided to go with bolt : 4 cone washers : standard washer because the standard washers fit the shape of the crush plate hole better. I think that is why I originally lost the torque on the bolt. The standard washers coned and took the shape of the crush plate hole.

Prop progression
1st

2nd

3rd

I got bored

 

[AX-O]

A thought for you--------in the photos above about cutting the cowl exit------have you thought about putting a hinge on the part you cut out, and making it into a cowl flap that can be opened for climb, closed for cruise???

A quick flight with the aft wing fairings on would let you know if the sluggish handling and heavy wing are due to flying without them...........or is this a part that is not readily removable when installed???

Mike,
Cowl flap will be implemented in the future. I have been researching that in great detail. I don't want one like the one currently being sold for RVs, I want one that the entire surface moves (to include the trailing edge).

The aft wing fairings are not a quick on/off thing. In fact I have not made them yet. I am going to tuff the interface of the wing/fuse and see what is going on back there before a make them. I also have some F1 fairings that I will cut up and play with. Aerodynamically, there is a lot to be gained back there. I never said "sluggish". The plane has heavier control forces when compared to my previous RV. It could be the radius of the trailing edges or it could be the geometry on the controls/bell crank/tubes. The holes are where I drilled them, not where they came from the factory

 

[DanH]

He sent Nicole over to grab these cone shaped washers. I forgot the name of them. Put 4 of these back to back on each bolt and also a regular washer.

Ax, they're called Belleville washers, and they're installed like this, between a pair of 960 or 970 washers:

Results: Although OATs at 8000 DA were 2 deg warmer than previous data collected, the oil temps went from stable at 217deg f to stable at 209 deg f. The crude test worked! OMG, 8 deg cooler (everything else almost constant) just because some tape. I did not even wrap tape from the top of the firewall to the tube. So that will be the next thing I attack. A nice exit fairing.

So what did the CHT's do?

 

[AX-O]

Thanks Dan. Will add another washer. Although when i called saber he only added the thickness of one regular washer.

Dang it. Forgot about the CHTs. No change. They remained at the 360s.

 

[AX-O]

Respectfully requesting no thread drift. Thanks.

 

[Whitman]

Axel, it would be a shame if this thread went to 38 pages

 

[DanH]

Thanks Dan. Will add another washer. Although when i called saber he only added the thickness of one regular washer.

Not a big deal. I like a washer under the bolt head in an app like this, mostly to protect it from the edge of the hard Belleville when turning the bolt. As Bill pointed out, maybe it's not necessary. Main thing is to install the Bellevilles correctly, or they are just ballast.

Dang it. Forgot about the CHTs. No change. They remained at the 360s.

OK. Darn, wish you had gotten before-and-after air temperature and pressure at the cooler face.

 

[AX-O]

OK. Darn, wish you had gotten before-and-after air temperature and pressure at the cooler face.

Will order the rest of the stuff today. Was having issues finding the temp probe.

Nothing is permanent yet. The tape will be removed and a permanent fairing will be installed. I plan on doing before/after measurements.

I am trying to learn the plane, the electronic gadgets and appropriate set ups. Lots of stuff going on at once.

 

[rv7boy]

Belleville washers are springs

<SNIP>Main thing is to install the Bellevilles correctly, or they are just ballast.<SNIP>

Absolutely. A Belleville washer is a type of spring. Belleville washers should be specified by someone who knows their "spring constant" values and who specifies their correct orientation if used in a stacked configuration. A design engineer can get all kinds of combinations of axial forces by stacking them in "series" or "parallel" groups. I was exposed to incorrect installation of Belleville washers many years ago as a young engineer as their incorrect installation was playing havoc with a clamping device until we figured out the orientation problem.

 

[AX-O]

Just adding the link to the starter failure.

http://www.vansairforce.com/community/showthread.php?t=131528

 

[Brian Vickers]

Weight and oil door

I just scanned through your extensive documentation and am impressed with everything. What did the final weight come out to? Also, I noticed a photo of the oil door on the upper cowl, but couldn't make out the method or securing it closed. I need to come up with a better mouse trap then the original design so am looking for ideas.

Sincerely

 

[AX-O]

I just scanned through your extensive documentation and am impressed with everything. What did the final weight come out to? Also, I noticed a photo of the oil door on the upper cowl, but couldn't make out the method or securing it closed. I need to come up with a better mouse trap then the original design so am looking for ideas.

Sincerely

Empty =1,000 lbs. I put stuff that other lighter -4s may not have. Like a thicker (than vans) canopy, 2 auto pilot servos, extra battery for avionics, arm rests, leather pockets, fire ext, electric flaps, garmin 430W and so on. I also placed maintenance ease over light in order to minimize 4 letter words in the future. I am not happy with the weight but I am happy with the performance thus far. I was aiming for 975lbs. So my fix was to lose 26 lbs and my wife lost 20 lbs.


I use a pin to hold the door closed. It comes from the cockpit through the cheek in a small tube. The hinge has a spring. I had to do it that way because I have an engine plenum. My other -4 had a pin also but I could reach it from the front inlet.

 

[AX-O]

Finally... flight testing continues. I was able to log approx. 4 hrs this weekend. I installed a new Catto 2-bladed test prop (more pitch). This one got me closer to where I need to be but still not quite there yet.

Disregard the fuel flow figures on the screen captures. The FF and fuel level are not completely calibrated.

Firsts for the plane:
-WOT
-Full fuel tanks (discovered a fuel leak in the BNC center pin)
-First time landing at a different airport (Rosamond, CA)

Static rpms on the ground 2080-2100.

at 8000 ft DA and 2700 rpm, 179 KTAS

at 8000 ft DA and WOT (2840 rpm), 187 KTAS

at 11.5 msl and WOT (2800 rpm) TAS dropped off a few knots, 184 KTAS.

I think I can pick up a few more knots. My horizontal stab incidence angle is too high. I have to zero it out. I don't have my aft wing fairings on yet, and I have not installed the cowling exit fairing yet (just speed tape right now until I can tuff the area). Max torque for this engine is at 2600 rpm. Once I get the right pitch prop, that will help too.

First in-flight pic. not great but proof that she flies. Thanks Goose.

 

[AX-O]

Just adding the PMAG wire issue.
http://www.vansairforce.com/community/showthread.php?t=132705

 

[AX-O]

Still in Phase 1. slowly getting there.

Testing Google photo capability.

 

[AX-O]

Last Sunday I got to 40 hours on the aircraft. Although that is the number assigned to my aircraft for exiting of Phase 1, I have not completed all the test and I am not comfortable taking anyone along yet. So it will remain in Phase 1 until she (and I are ready).

After landing I did a mag check and one of my ignitions did not pass. The PMAG dropped cylinder 3 and 4 (OMG, how nice it is to have an engine monitor with history data). I pulled the PMAG, talked to Brad, over-nighted it to TX yesterday, and will get the fixed PMAG back tomorrow. The failure was to the coil that puts out spark to cylinder 3 and 4. They replaced the coil at no cost and they have been extremely responsive and helpful. In the process of checking the mags I found out that I got my left and right labels mixed up on the PMAG switches. The plane operated as if nothing happen while it operated on one mag.

After first flight, most people stop posting and sometimes it is difficult to understand if a change worked or not. So?..

- if you have a Superior cold air sump, calibrate the engine oil stick. It is way off. Do so by adding 3 qts for the initial reading then add 1 qt at the time and mark your stick. It is a non-linear relationship. I used a hole-puncher to mark the location at 3, 4, 5, 6 and 7 qts.

-I removed the Rod Bower's air filter. It kept coming lose. The 3 set screws on the unit were not enough to hold the unit on the fuel servo. I spoke to other folks with the same feedback. I call Don at Airflow performance and he made me a "Y" intake tube for the FM-100. That is working much better though I now have to figure out a way to add an air filter inside the cowl.

-The last configuration of oil cooler, oil cooler location, oil cooler orientation and engine plenum interface seems to be working. As the OATs go up I am starting to see CHTs going up too. So I may not be done sizing the in/exit area. For the most part the oil temp is operating at approx 135 deg warmer than OATs in flight. Now that I have a good Idea on how she is operating, I will start the cowling instrumentation (per DanH?s guidance), Cowl flap design (similar to DanH?s) and exit area clean up.

-My airspeed indicator is showing 2 to 3 kts slow depending on the airspeed being flown. So all those people that keep saying the safe air static ports don?t work?. Well, mine does fairly well. I don?t have the means to measure instrument error so the total error is being blamed on the pitot-static system/location error.

-I spoke with Nicole Catto. I am going to the 5 th prop design. They are moving to a 68 by 84. She told me that this will be the one. Fingers crossed. They are reducing the cord width and prop length to increase the takeoff rpm and increasing the prop pitch to reduce the cruising rpm to 2700. With the airspeed error taken into account, the plane is cruising at 189 KTAS. Hopefully I can see 190 straight and level after this change. If not, after the aft wing fairing and horizontal angle of incidence get worked out.

- I replaced a set of brake pad at 38 hrs. That is ridiculous. I had my other plane for over 400 hrs and replace the pads once. This aircraft rolls much easier than the previous one and I keep 40 psi on the tires vice 35 on the previous, so it taxis really fast. I am always taping the brakes. Also I have been landing long in case I have engine failure but still trying to make the first taxiway so I have been using the brakes. I always pump the brakes prior to start and prior to landing. Well I did that prior to start and my pedal went limp. Got out and saw a puddle. #$%^@ turns out the brake puck came out because my pad was so thin. Will keep a closer look at this. My previous plane ate tires for breakfast. This one may eat brake pads.

- got the heavy wing fixed by re-rigging the flap up on the light wing. One turn on the flap rod did the trick. I then lined up the light aileron to the flap position in flight configuration. Which interestingly is not the same position as it is on the ground when retracted.

-Bags of dog food facilitated cg range testing. My dogs will have food for a few months now. Kind of like those folks that prep for the end of the world.

 

[sblack]

Thanks for posting. I hope to get there 1 day....

 

[simpkinsona]

EGT

That PMAG problem explains your EGT fluctuations from another thread

-Andy

 

[MK77]

Google Photo

Totally unrelated question but how did you get the photos embedded from G Photo? I can never seem to figure it out now that they switched from Picassa.

 

[Billythekid]

Why a fastback? Looks ? Or performance? I'm a newbie so I must ask.

 

[sblack]

There is a considerable drag reduction with a fast back. The airflow behind a stock canopy on a -4 or -8 is completely separated.

Looks are in the eye of the beholder.

 

[AX-O]

All, i am respectfully requesting no thread drift. This thread is to document my work and build so others can use it. I rather not discuss items on this thread that can be easily found on VAF using the search function. That being said, some answers below.

That PMAG problem explains your EGT fluctuations from another thread

-Andy

Unfortunately that is not the case. No change after receiving the fixed PMAG.

Why a fastback? Looks ? Or performance? I'm a newbie so I must ask.

Billy, the short answer is both. I like the looks and in theory it does reduce drag. However, i wont know how much because this is the only configuration this aircraft will be in. Use the "search" function on VAF. This has been previously discussed. If you want more info, send me a PM with your phone number and i will give you a call. Good luck with you build.

The airflow behind a stock canopy on a -4 or -8 is completely separated.

I am an Aero Eng and would not personally make this statement. "Completely" is not a true statement. There is 3D flow around the canopy. Meaning the flow around the sides of the canopy also affect the flow coming off the back. Without flow/drag measurement all we can say is that the fastback is more efficient based on aerodynamic theory. We can't say by how much unless we measure it.

It does however look cool!

 

[AX-O]

Folks have been asking how it is going lately.

I took my wife (and the plane) on the first trip outside our area. My wife absolutely loves the plane and told me she is attached to it already. She is really happy with the additional room that the rocket canopy/fastback offers.

A few people got to see Dilemma for the first time at the formation clinic. All the comments/feedback were positive. I learned that I don't like the pitot tube location because it complicates tie down. My other plane had the aluminum pitot line and had more clearance.

The plane flies nice. I slightly adjusted the auto pilot gain levels on this trip. It is faster than the previous plane by exactly 20kts. it also burns 1.3 gal less per hr. I love the auto pilot options to set air speed or ROD when climbing or starting to let down from high altitude. The engine temps are doing well but it is still cold outside. We will see what will happen once we start warming up again. I got a few tricks up my sleeve for cooling. I started work on a cowl flap like the one DanH made for his plane. I am not complete but some pics shown below.

Our first away from home picture

BBQ at our friends house

The all-up flight

And the nice thing about flying with your buds, nice pics.

A few of the cowl flap. It will get a trim motor later. Right now is set with two AN3 bolts. I still have to make the torque tube and a friend is trying to figure out how to take CHT/oil temp and automatically open/close the cowl flap. It is 9 inches wide so opening up the cowl flap one inch gives me 18 additional inch^2 to the exit. A 50% increase in exit area.

 

[Gash]

Beautiful airplane Axel. Thanks for the update! Great seeing you at Madera and thanks for all the good work you did there!

 

[skylor]

Photo Bomber...

Hey, nice crop job on the fourth picture!

Skylor

 

[JoeBlank]

Nice looking bird AC! I enjoyed looking over your work at Madera.

Of course checkerboarding the cowl flap will certainly increase the flow rate/volume too...

 

[Low Pass]

Very nice project, and very nice timing on that cowl flap! Have been recently considering a similar mod myself. Appreciate you sharing those photos.... Might just borrow some of your IP.

 

[sblack]

Is paint on your radar at this point? Do you have a scheme picked out? The fastback has such nice lines. I look forward to seeing that.

 

[jchang10]

What about the exhaust fairings? Looks like you started to do something there. That is one thing i wish Van would improve: better exhaust fairings. I looked at a Lancair ES and was duly impressed by what they did. Something similar to the photo below but better. I hate how the RV-10 exhaust pipes just hang down at different angles.

 

[smokyray]

Fast-Back to the future...

Folks have been asking how it is going lately.
I took my wife (and the plane) on the first trip outside our area. My wife absolutely loves the plane and told me she is attached to it already. She is really happy with the additional room that the rocket canopy/fastback offers.

Axel,
My wife made the exact same comment after I sold my Four "The Bandit" and bought a Rocket project. Once she started flying in the HR2, all others were rubbish!
BTW, it was great meeting you during the pre-purchase on your former four...
V/R
Smokey

PS: A true mark of comfort for a wife back-seater is to check Six and see her snoozing away during rare level flight excursions...

 

[AX-O]

Hey, nice crop job on the fourth picture!

Skylor

that was George. He did a good job with that one.

Of course checkerboarding the cowl flap will certainly increase the flow rate/volume too...

Joe, i am on it. I did not realize the rate/flow would be incresed by simple checkers.

Might just borrow some of your IP.

Borrow all you want, that is why i post. That being said, that is a modified DanH cowl flap.

Is paint on your radar at this point? Do you have a scheme picked out?

It will be a while before she is ready for paint. Sorry, I share a lot about this build but the paint job is the one thing that i am not sharing until its painted.

What about the exhaust fairings? Looks like you started to do something there.............I hate how the RV-10 exhaust pipes just hang down at different angles.

There is still a lot of things i want to try on the exit area. but it is much harder now to work on the plane becase it is flying and it is no longer in my garage. So things drag on and on.

If you dont like the way your pipes look, fix them. Learn the skill set required and go for it!

PS: A true mark of comfort for a wife back-seater is to check Six and see her snoozing away during rare level flight excursions...

I turned around to check on her and she had both hands behind her head leaning back (like in a sofa watching the real house wives) looking at the airliners above us.

 

[AX-O]

Update:
Well…. The first conditional inspection is almost completed. I can’t believe she has been an airplane for a year now. I was only able to fly her for about 55 hours in the first year as there was a lot (I mean a lot) of what we call “fly-fix-fly” mods. The most significant were the numerous oil cooler and oil cooler configuration changes to include the engine plenum.

I have not found anything unexpected during the conditional inspection as I have kept a close eye on things. Taking things apart, cleaning, lubricating, etc. more than usual. The small things I added in the build process to simplify maintenance have really paid off. IT IS IMPERATIVE to think about how you will maintain the aircraft during the build process. If there is something you don’t want to open up, or crawl into or just plain do; figure out a way to overcome that issue during the build process.

I did take the time to make a few “upgrades”.
-Added a 5th harness strap for my wife.
-Painted a few interior parts.
-Reset the control stick to the right so it would be more ergonomically suited for my flying position.
-Made/installed an exit fairing at the bottom of the fuse covering the engine-mount cross-tube. This was a new concept for me. I let a friend (Brian, future RV builder) make the part and just provided guidance and requirements. It turned out very well, flight data to come at a later date. I also came up with a way to interface the new fairing with the DanH’s style cowl flap. Will post pics later.

Discovery
In the process, I discovered that the injector restrictor nozzles on the 340 were .028. Long story short, Don at Airflow Performance (the nicest, most supportive vendor I have ever talked to) is sending me .022 restrictor nozzles. That should also help with my idle issue. Fingers crossed. Will report out later.

Still to do:
-Arrive at the final rudder trim wedge size. Slowly cutting it down.
-Make aft wing root fairings.
-Reset the incidence angle on the horizontal stab.
-Motorize DanH’s style cowl flap. Brian is working on a concept to automatically open/close the cowl flap based on engine temps and also provide the capability to override the position.
-Install the right pitch/length prop. Waiting on the 4th version.

Keep pounding rivets, running wire and sanding fiberglass. See you at OSH.

 

[AX-O]

Dilemma went to the Reno for Pylon Racing School (PRS) http://www.vansairforce.com/community/showthread.php?t=139124

The exit fairing did improve the airflow out the bottom of the cowl. I left the oil on the belly for about 15 hrs and the patterns look much less undisturbed. Will try to post pics later.

Oil temps are rising at a slower rate and end up 8-9 degrees below previous conditions.

The cowl flap is also working well, lowering the oil temps with minimal impact on airspeed. The airspeed drop is almost immeasurable with a 1 inch opening (adds 16 in^2 of exit area or almost 50% increase in exit area). I still need to make this adjustable in flight. It is still only adjustable manually on the ground (2 AN-3 bolts). By the way DanH, many folks at Reno liked the concept of the cowl flap.

The next prop from Catto showed up (this one was $$$$, it has the nickel edges). Craig completely changed the prop profile. It went from a 70X76 to a 68X84. The overall blade is significantly narrower. He wanted to get my RPMs up on the ground and keep the engine around 2700 in cruise. Will see how it does.

 

[AX-O]

I have had some time to fly the new prop. Comparison of the props below. Additional feedback from my wife is that the prop looks too small everyone is a critic. Next prop is under development right now. Craig is trying a completely new blade design. The blade will be modeled similarly to a 787 wing tip. He is also going back to a 70 inch diameter. The one thing I have not done is compared the props at the same MAP. I did not have the time to collect the data prior to the OSH trip.

787 wingtip

data collected

 

[AX-O]

I got some pics of the prop today (mentioned on previous post). Should be ready in a few days. This one is 70 X81 and designed for an RPM of 2,800 WOT at 8,000 ft DA.

 

[chrisbryanolsen]

No Pics

AC,
Hey I am not seeing the pics, are they shared ?