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-   -   Speed Mods? (https://vansairforce.net/community/showthread.php?t=159520)

Chippster1 04-11-2018 07:45 PM

Speed Mods?
 
There seems to be a paucity of aftermarket products to make an RV-10 go faster. Is it because it is already so perfectly designed?
Does anybody know of any mods worth looking at?

Kyle Boatright 04-11-2018 08:01 PM

The Showplanes cowl should be something of an improvement.. Also, Jesse Saint sells a set of wing/fuse intersection fairings for which he claims a speed improvement. I think Sam James sells a narrower set of wheel fairings which should help.

After that, you're down to rigging and HP as fas as I know.

Veetail88 04-11-2018 08:39 PM

Totally OT, but paucity, had to look that up, good job.

Carl Froehlich 04-12-2018 07:46 AM

I built using the James Cowl, Plenum and Wheel Pants. This added time to the build but I'm happy with the performance (a couple of screen shots attached). The plane has a stock engine and prop from Van's.

James Cowl no longer offers the cowl for the RV-10, but you can still get the wheel pants. They have a smaller frontal area than the stock Van's pants but again add a little time to the build.

Don't underestimate the value of rigging. Rigging is more than just wings level and the ball in the middle.

Carl



TShort 04-12-2018 08:33 AM

I have this thread bookmarked in my RV-10 folder:

http://www.vansairforce.com/communit...ad.php?t=95952

BillL 04-12-2018 08:48 AM

Quote:

Originally Posted by Carl Froehlich (Post 1252583)
Rigging is more than just wings level and the ball in the middle.

Tell us a little more about the procedure to ensure this please. My 7 has stock M1B, Hartzell composite prop, SJ cowl, my plenum, SJ pants and is only a few mph better than the vans stock reported speed at ROP cruise. I have some tweaking to do, but a little more about exactly what you are talking about would be appreciated. I am feeling like something is not right, but don't know exactly what. I was expecting my 180 hp engine to be equal to or best the 200hp published numbers, but it falls a little short. Only 12 hrs into PH I.

I don't think it is just my little transponder post, but I am considering installing the Vans PR wheel pants.

Bob Martin 04-12-2018 10:18 AM

Quote:

Originally Posted by BillL (Post 1252607)
Tell us a little more about the procedure to ensure this please. My 7 has stock M1B, SJ cowl, my plenum, SJ pants and is only a few mph better than the vans stock reported speed at ROP cruise. I have some tweaking to do, but a little more about exactly what you are talking about would be appreciated. I am feeling like something is not right, but don't know exactly what. I was expecting my 180 hp engine to be equal to or best the 200hp published numbers, but it falls a little short. Only 12 hrs into PH I.

I don't think it is just my little transponder post, but I am considering installing the Vans PR wheel pants.

Bill,
No expert here, but....
I have seen/worked on two -6's that did not have the wings straight/perpendicular to the fuselage. When they are not the same, one needs more rudder trim and that is drag.

Carl Froehlich 04-12-2018 11:58 AM

Quote:

Originally Posted by BillL (Post 1252607)
Tell us a little more about the procedure to ensure this please. My 7 has stock M1B, SJ cowl, my plenum, SJ pants and is only a few mph better than the vans stock reported speed at ROP cruise. I have some tweaking to do, but a little more about exactly what you are talking about would be appreciated. I am feeling like something is not right, but don't know exactly what. I was expecting my 180 hp engine to be equal to or best the 200hp published numbers, but it falls a little short. Only 12 hrs into PH I.

I don't think it is just my little transponder post, but I am considering installing the Vans PR wheel pants.

You don?t mention the prop you are using. This makes a big impact.

The rigging topic itself is way too wide a subject to adequately respond. The first thing I recommend you do is get other experienced builder eyes on your plane and start looking for the obvious, then get the straight edges out and measure everything. As example, I was with a buddy visiting open hangar doors. An RV-4 owner mentioned that he was not sure his plane (flying for 15 years) was ever rigged right. The right flap hanging down a half inch from up jumped out at me, and from there all the other classic ailerons high/low mount problems. He gained 5 knots after a few simple corrections.

Wheel pant rigging is another ?hard to get just right? issue.

One item that is less obvious is the HS angle of attack. In normal cruise, is the elevator trailing edge hanging down? If so, this tells you the HS is providing too much downward force. In the 8A a 0.040? shim under the HS forward spar made a hugh difference - so be careful. In the RV-10 I needed to add a 0.063? shim to get the elevators in perfect trail for normal loads. If you are thinking of adding a shim bigger than that, time to stop and look at what else is going on.

So - call your buddies to come on by. After you fix stuff your wingtip trailing edge may by out of wack. Don?t be afraid to glass over the wingtip holes and re-drill it.

One other point. This is not a ?one and done? deal. It is an iterative process. Make it part of your 40 hour test program.

Carl

RV10inOz 04-13-2018 03:26 PM

Carl, that is way faster than Vans numbers, have you checked your TAS vs flying a GPS box to verify static error?

If the static is pretty close you have one slick machine! :eek:

Carl Froehlich 04-13-2018 04:02 PM

Quote:

Originally Posted by RV10inOz (Post 1252936)
Carl, that is way faster than Vans numbers, have you checked your TAS vs flying a GPS box to verify static error?

If the static is pretty close you have one slick machine! :eek:

My checks show TAS readout is about right. There is no magic here. The cowl/plenum setup has less cooling air coming into the engine, so less drag. The plenum uses the cooling air about as effectively as possible. I do offer that there is a trade off. I find cooling is fine for how I fly. It would not be adequate if you want to do a 100kt climb to 10K?. I climb at 130kts to keep the engine cool.

Carl


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