http://www.vansairforce.com/community en Sat, 21 Nov 2009 03:13:08 GMT vBulletin 60 http://www.vansairforce.com/community/images/misc/rss.jpg http://www.vansairforce.com/community http://www.vansairforce.com/community/showthread.php?t=50772&goto=newpost Sat, 21 Nov 2009 01:46:05 GMT is anyone considered the jab 3300 for the rv-12? i know the stock answer of build it as designed, but where is the fun in that? i have had great service from jabs over the years and like the price. is anyone considered the jab 3300 for the rv-12? i know the stock answer of build it as designed, but where is the fun in that? i have had great service from jabs over the years and like the price. ]]> RV-12 titanhank http://www.vansairforce.com/community/showthread.php?t=50772 http://www.vansairforce.com/community/showthread.php?t=50771&goto=newpost Sat, 21 Nov 2009 01:33:09 GMT RV12 Drag curve

Goal: Develop an understanding of RV12 performance by estimating the RV12’s Drag curves

Disclaimer: I know enough about aerodynamics to know that I do not understand it.

Intent of this post: To start a discussion about these fundamental characteristics of the RV12.

Assumptions: Sea Level, standard day, aircraft at maximum gross weight, flaps up

Start: RV6a Drag information from the Café Foundation APR (aircraft performance report) of the RV6a. This test can be found at: http://cafefoundation.org/v2/pdf_caf...inal%20APR.pdf

From the RV6a drag graph in the report, the coordinates of the induced and parasitic drag data points were obtained. This data was then entered into Excel and curves fit. Induced drag is supposed to equal a constant divided by the square of the airspeed. Parasitic drag is supposed to equal a constant times the square of the airspeed (from Aerodynamics for Naval Aviators). My goal was to find the constants that resulted in the best fit. These are the formula of the best fit lines.

Induced Drag (pounds) = 764669.98 / CAS(mph)^2
Parasitic Drag (pounds) = 0.00594791 * CAS(mph)^2

Total Drag is the sum of the Induced and Parasitic drag values at each of the airspeeds.

Creating the RV12 Drag Curve Estimates:

Theses estimates were created following these (possibly misguided) ideas:
Began with the induced curve
1) Shifted the stall speed by 3 mph (RV6a reported stall 55 mph cas, RV12 is 52). Since both share essentially the same airfoil (RV6a 23013.5, RV12 23014) they should therefore stall at essentially the same angle of attack.
2) Adjust for different gross weights (RV6a 1650, RV12 1320). Induced drag is proportionate to weight; after all it is the backward vector component to the wing’s lift.
3) Induced Drag (pounds) = (1320/1650) * 764669.98 / [CAS(mph) + 3]^2

Then proceeded to the Parasitic curve.
1) The two aircraft have essentially the same fuselage cross-section and length. The RV12 has a longer wingspan and area. The RV6’s gear was faired while the RV12’s are not. The RV6a is flush riveted while the RV12 uses low profile rivets.
2) The RV12’s best glide speed and therefore the speed where parasitic drag and induced drag should be equal (by definition) is, according to the POH, 98 mph.
3) The coefficient for the parasitic drag curve was adjusted until the parasitic and induced drag at 98 mph were equal.
4) The resulting coefficient for the RV12 (0.00624409) is larger than the RV6a (0.00594791) and steepens the curve, indicating that the RV12 has more parasitic drag than the RV6a. The ratio of the coefficients (RV12/RV6a) is 1.04979. In other words the RV12’s parasitic drag is about 5% greater than the RV6a.
5) RV 12 Parasitic Drag (pounds) = 0.00624409 * CAS(mph)^2

From these curves the following can be determined (maybe):
1) The Total Drag curve, also known as Polar Drag, can be drawn by adding the induced drag and parasitic drag values at each of the airspeeds.
2) Carson’s speed, (optimal cruise) can be determined by finding where a line drawn from the origin will be tangent to the Polar Drag curve. By visual inspection this appears to about 129 mph
3) According to the Café papers:
Thrust Horsepower Required = AS (mph) * Drag (lbs) / 550:
Which at best glide speed (98 mph) is 21.37 THr, at minimum decent speed (min power required) (72.6 mph) is 18.47 THr, and at 135 mph is 35.82 THr.
4) Minimum decent speed is the low point on the Thrust Horsepower required curve. According to the Café papers: Sink rate can be calculated from:
Sink rate (fpm) = drag (lbs) * speed (fpm) / weight.
At the Minimum decent speed of 72.6 mph the calculated sink rate is 677 fpm producing a glide angle of 6.1 degrees.
5) Maximum range glide (best glide speed) is 98 mph (from POH). At 98 mph the sink rate calculates out to a 784 fpm glide, which results in a minimum glide angle of 5.2 degrees.
6) From the RV 12 and RV6a parasite drag curves coefficients, and knowing that the RV6a flat plate area is 2.32 sq ft (Café Report) the calculated equivalent flat plate drag area of the RV12 calculates to 2.436 sq ft. Again about a 5% difference.


The Graph:

[Tried to post without any luck.]


Assistance/corrections from someone who actually understands this stuff would be appreciated.

Can someone add the plot of the Thrust Available from the Rotax and prop used?

Regards, Dave ]]> RV-12 DaveLS http://www.vansairforce.com/community/showthread.php?t=50771 http://www.vansairforce.com/community/showthread.php?t=50726&goto=newpost Thu, 19 Nov 2009 22:47:07 GMT By far the worst day in 3 months of steady 5 8-hour days per week. Spent 8 hours trying to make one longeron and probably just have an expensive piece of scrap. The ONLY way to open the angle to 95.4 degrees was to beat on it with a LARGE hammer. Squeezing didn't work and neither did a soft mallet. That opened it but it also caused the longeron to bend up-- the wrong way, Taking out the bend resulted in a wavy upper surface. Using the recommended "metric cresent wrench" to twist the forward part resulted in more bending and a wavy inside surface-- and also variation in the 95/4 degree angle. Gave up with an approximation of the recommended shape and tried putting in the curve. Soft Mallet had NO effect. Called Van's and was told to use a 3-4 pound hammer to bend the longeron. Bending in the curve was slow and also resulted in a bend downward in the longeron. Bending it back up takes out some of the curve and-- guess what-- adds more waves. Test fitting to clecoed verticals on the fuselage side indicates a pretty poor fit and some twist that's going to put a strange curve in the fuselage side. 8 hours on one longeron and no enthusiasm to start the right one.

I see no way to make an accurate piece with a hammer, vise, and crescent wrench. I'm not real enthusiastic about proceeding to assemble the airplane with a piece this poor in place-- two of them since I don't see any way to make the right one better.

Anybody making preformed longerons? If not. there may be a partially completed kit for sale.

Wayne 120241
Emp kit completed
Wing kit completed
Fuselage kit stall because of longerons
Avionics and finish kits in hand, engine enroute ]]> RV-12 yankee-flyer http://www.vansairforce.com/community/showthread.php?t=50726 http://www.vansairforce.com/community/showthread.php?t=50650&goto=newpost Wed, 18 Nov 2009 04:48:24 GMT I posted this last night. Several said that the thread should be deleted, so I deleted it. Apparently many people didn't get to see the last post so I have been requested to re-post.

Thanks to Scott Risan, I now have sufficient information to perform a complete and competent inspection on the RV-12 as an E-LSA. Scott has been very patient throughout my e-mails over the last several weeks and has worked with me in a very professional manner.

I apologize if I have cast any shadow on the RV-12 design. That was never my intention. Van's Aircraft has done a fantastic job with the RV-12 and the kit.

As far as the RV-12 as an amateur-built aircraft, the jury is still out. To be certificated as an E-AB, the builder may need to show more detail than normally expected. I'm still working on this.
Hopefully Van's will submit the RV-12 kit to the FAA for approval on the 51% approved kit list. That would help greatly. ]]> RV-12 Mel http://www.vansairforce.com/community/showthread.php?t=50650 http://www.vansairforce.com/community/showthread.php?t=50640&goto=newpost Tue, 17 Nov 2009 23:34:12 GMT Just about to start the wings and had a quick look at the wing spars this evening - still in their bags.

Are the main spars anodized or 'clear' primed from the factory? Forum search shows up both as being possible.

Being in the UK where it rains occasionally, priming is the norm.... ]]> RV-12 aerofurb http://www.vansairforce.com/community/showthread.php?t=50640 http://www.vansairforce.com/community/showthread.php?t=50614&goto=newpost Tue, 17 Nov 2009 04:21:18 GMT What is the best way to smooth the seam in the rudder cap?. Mine has a very pronounced "v" along the seam.From what I have gathered from other posts, the resin used is polyester if the part is gelcoated. Is it better to use resin with flox or micro bubbles, or some sort of filler like bondo? If I go with the resin, do I remove all the gelcoat in the area, or just rough it?

Thanks ]]> RV-12 Mark Henderson http://www.vansairforce.com/community/showthread.php?t=50614 http://www.vansairforce.com/community/showthread.php?t=50569&goto=newpost Mon, 16 Nov 2009 02:13:05 GMT I've just installed the flap handle and associated hardware. Even with careful installation and prior measurement, the end result is that the flap handle assembly chafes against the brake lines and wire harness. The amount of "rub" is small, i.e. not much surface area against the brake lines, but still its rubbing. Any practical way to "fix" the rubbing?

Thx! ]]> RV-12 Mike Buettgenbach http://www.vansairforce.com/community/showthread.php?t=50569 http://www.vansairforce.com/community/showthread.php?t=50516&goto=newpost Sat, 14 Nov 2009 21:36:11 GMT I know I've seen a good side photo or drawing of the RV-12 emblem or badge but can't find it now. I'd like to have a couple of caps made with the logo. Anybody point me to it (drawing preferred)? Thanks!!

Wayne 120241 N143WN ]]> RV-12 yankee-flyer http://www.vansairforce.com/community/showthread.php?t=50516 http://www.vansairforce.com/community/showthread.php?t=50491&goto=newpost Fri, 13 Nov 2009 21:51:37 GMT Hi all,

Just FYI, some Rotax dealers are starting to be informed of a 10% increase in the price of Rotax engines coming sometime in 2010. I havn't gotten any more details than that.

So better smoke 'em while you got 'em, i.e. don't put off purchases of engines for too much longer....

LS ]]> RV-12 lucien http://www.vansairforce.com/community/showthread.php?t=50491 http://www.vansairforce.com/community/showthread.php?t=50484&goto=newpost Fri, 13 Nov 2009 17:42:02 GMT The CDI needle did not appear on my Dynon HSI display. The CDI needle appeared just fine on the Garmin 496 HSI display. Called Dynon this morning. To get the CDI needle to appear on the Dynon display, Dynon tech support indicated that a setting has to be changed in the 496. It may be the same... The CDI needle did not appear on my Dynon HSI display. The CDI needle appeared just fine on the Garmin 496 HSI display.

Called Dynon this morning. To get the CDI needle to appear on the Dynon display, Dynon tech support indicated that a setting has to be changed in the 496. It may be the same for the other Garmin GPS units.

In the 496 setup menu. Start at the Main Screen, Scroll down to SETUP, Scroll right to INTERFACE, Scroll down to Interface Type, Press MENU, as opposed to enter, Go to Advanced -- NMEA Output Setup -- Change it From FAST to NORMAL

Stein confirmed the change and indicated the change has been implemented. Only the early avionics kits were shipped with the incorrect parameter in the GPS. ]]> RV-12 MartySantic http://www.vansairforce.com/community/showthread.php?t=50484 http://www.vansairforce.com/community/showthread.php?t=50460&goto=newpost Thu, 12 Nov 2009 20:53:08 GMT Hi all,

I have been getting a few calls asking if, or when, a ULPower UL260i FWF package would be available for the RV-12.
www. ulpower.com

The UL260i is now rated at 97hp and the 260iS is at 107hp.

I'd like to offer a very good deal to anyone that would like to work with me in getting a FWF going for the 12. For example I would build your forward fuselage, and develop a FWF and install and test it for the cost of materials and engine. Or maybe a better solution, I am open to ideas. I would like to complete this by spring and have it tested by Sun n Fun.

I am located in Edgewater FL, midway between Daytona Beach and Cape Canaveral. Please email me at Gus@flywithgus.net

Thanks,
Gus Warren
www.flywithgus.net
North American distributors for ULPower Engines. ]]> RV-12 Fly with Gus http://www.vansairforce.com/community/showthread.php?t=50460 http://www.vansairforce.com/community/showthread.php?t=50449&goto=newpost Thu, 12 Nov 2009 17:46:26 GMT After dealing with Pro Seal on my other RV's I was not looking forward to it on my RV-12. So, when local RV tank builder, Evan Johnson, offered to build my tank he did not have to ask twice. I had Van's ship my tank direct to Evan and it was completed in no time. Evan is in Redding, CA. at O85 and can be reached at (530)351-1776.


http://i37.tinypic.com/k1xx08.jpg ]]> RV-12 pmshep http://www.vansairforce.com/community/showthread.php?t=50449 http://www.vansairforce.com/community/showthread.php?t=50447&goto=newpost Thu, 12 Nov 2009 17:19:17 GMT Are there any guidelines for setting the prop. My is set at max course (cruise). Take off rpm is 4860. Single pilot rate of climb is 1500 to 1700 fpm dual pilot is 900 fpm. At full throttle I am able to get 5300 rpm max at 3,000 ft. Should I be able to get 5500 rpm? Anybody have any ideas... Are there any guidelines for setting the prop. My is set at max course (cruise). Take off rpm is 4860. Single pilot rate of climb is 1500 to 1700 fpm dual pilot is 900 fpm. At full throttle I am able to get 5300 rpm max at 3,000 ft.

Should I be able to get 5500 rpm? Anybody have any ideas of what is optimum or is it just personal preference?

Thanks ]]> RV-12 RGaines http://www.vansairforce.com/community/showthread.php?t=50447 http://www.vansairforce.com/community/showthread.php?t=50434&goto=newpost Thu, 12 Nov 2009 12:01:48 GMT I ordered the materials from Aircraft Spruce but I am sure there are many other good sources out there so this is not an endorsement.

I also made one change to Pete's list. I doubled the Dacron Fabric from 1 to 2 yards. This is used as "peal ply" to get excess resin out of the fiberglass cloth.




PART# ORDERED
--------------------------------------------------------------------------------
01-14600 3M GLASS BUBBLES 1 LB. 1.00
01-14800 FLOCKED COTTON FIBER 1 LB. 1.00
01-00324 16 OZ MIXING CUP (PKG OF 25) 1.00
01-25800 MIXING STICKS BOX OF 500 1.00
09-00300 DACRON FAB 2.7OZ, 62 W #604 2.00
7781-60 FIBERGLASS CLOTH STAND 7781-60 2.00
01-08200 WEST SYSTEM EPOXY KIT A-2 SLOW 1.00

From Arlington where our weather has been great for flying,
Bob Kibby ]]> RV-12 Bob Kibby http://www.vansairforce.com/community/showthread.php?t=50434 http://www.vansairforce.com/community/showthread.php?t=50403&goto=newpost Wed, 11 Nov 2009 18:32:05 GMT Since we've installed the cooling shroud for the radiator, we're having a lot of problems getting the cowling to fit. We've got the radiator on in the front and it's resting against the muffler so I took it off and reinstalled the cowl but we're still having the same issues. It fits fine before we put the shroud on. Also, the cowl is now rubbing against the back of the spinner and we're noticing that the muffler is further aft on the tailpipe side and the #4 exhaust pipe is not secure in it's placement in the muffler. (it is not pulled in very tight.)
Anyone with similar problems?
Meade and George ]]> RV-12 meadeduck http://www.vansairforce.com/community/showthread.php?t=50403