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bsponcil(at)belinblank.or
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 Posted: Tue Nov 07, 2006 7:54 am Post subject: RV10 vs PA-28-235 |
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I went flying with a buddy of mine last week in his 235HP Pathfinder. On our way back from a $100 pulled pork sandwich, we had the benefit of a strong tailwind and my friend noted, with some satisfaction, that we were doing 180knots over the ground. Hmmmm, I thought. An RV-10 with the same engine would almost fly as fast in a still wind. I should also point out that my friend's pathfinder has EVERY speed mod you can buy (gap seals, fancy pants, wing fairings, etc).
So the question is, given the same power and nearly identical size/weight, how come the -10 is 30-40 knots faster than the cherokee 235? Is the wing just THAT more efficient? Is it the cowl? Flush rivets? Prop? Combination of all four? Even more surprising is the fact that you seemingly don't have to pay a price for that speed advantage. The RV-10 lands shorter, takes off shorter, climbs as fast and yet has more interior space. Amazing.
-Brian
#40497
N211BD
Iowa City, IA
[quote][b]
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jdalton77(at)comcast.net
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| Posted: Tue Nov 07, 2006 8:31 am Post subject: RV10 vs PA-28-235 |
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All of the above?
Add 25HP, a more efficient wing, a lighter plane, and flush rivets and it will go way faster. Who knew? (obviously Van did)
JEFF
[quote] ---
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jesse(at)itecusa.org
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| Posted: Tue Nov 07, 2006 8:32 am Post subject: RV10 vs PA-28-235 |
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Well, I think some of the reason is just that the Cherokee is afraid of liability because it is certified, so it just won’t let itself go as fast as it could. J
I don’t know a lot about the Cherokee, but I think it is a combination of all 4 issues, the wing, the cowl, flush rivets, prop, gear leg fairings and wheel pants (make 15-18Kts difference in our tests), better engineering available now than was when the Cherokee was designed so the strength is where it needs to be. There are probably a number of other factors also.
You know, on second thought, maybe you could trick the Cherokee into thinking it was designed by Van’s and see if that would make it faster.
Ok, back to being serious. We have looked at the Cirrus SR-22 a lot. It has more power, thinner and higher aspect ratio wings, is more aerodynamic because of the compound curves available with composites, yet it is only 5-10Kts faster in cruise, and is burning a lot more fuel at that. It needs about twice the runway to takeoff and land, and doesn’t seem to climb as well. It doesn’t have even close to the same full-fuel useful load and with full fuel won’t go as far. One reason is the SR-22 is a fair bit heavier than the RV-10, both empty. I don’t know the other reasons. Also I have heard that you really badly don’t want to get into ice in the SR-22 unless you have the anti-ice system, while I know we have picked up ice on a number of occasions with the -10 and it was hard to even notice a difference (although we didn’t stay in the ice any longer than we absolutely had to, not wanting to temp God). Maybe it is that certified thing again. Don’t fully know, but the more we look, the more we can’t find any plane that is all-around as good as the -10.
Now, where did I set that turbo?
Do not archive.
Jesse Saint
I-TEC, Inc.
jesse(at)itecusa.org (jesse(at)itecusa.org)
www.itecusa.org
W: 352-465-4545
C: 352-427-0285
From: owner-rv10-list-server(at)matronics.com [mailto:owner-rv10-list-server(at)matronics.com] On Behalf Of Brian Douglas
Sent: Tuesday, November 07, 2006 10:54 AM
To: rv10-list(at)matronics.com
Subject: RV10 vs PA-28-235
I went flying with a buddy of mine last week in his 235HP Pathfinder. On our way back from a $100 pulled pork sandwich, we had the benefit of a strong tailwind and my friend noted, with some satisfaction, that we were doing 180knots over the ground. Hmmmm, I thought. An RV-10 with the same engine would almost fly as fast in a still wind. I should also point out that my friend's pathfinder has EVERY speed mod you can buy (gap seals, fancy pants, wing fairings, etc).
So the question is, given the same power and nearly identical size/weight, how come the -10 is 30-40 knots faster than the cherokee 235? Is the wing just THAT more efficient? Is it the cowl? Flush rivets? Prop? Combination of all four? Even more surprising is the fact that you seemingly don't have to pay a price for that speed advantage. The RV-10 lands shorter, takes off shorter, climbs as fast and yet has more interior space. Amazing.
-Brian
#40497
N211BD
Iowa City, IA
| Quote: | | www.aeroelectric.com |
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-- Release Date: 11/7/2006
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11/7/2006
[quote][b]
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Tim(at)MyRV10.com
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| Posted: Tue Nov 07, 2006 8:56 am Post subject: RV10 vs PA-28-235 |
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The answer is, it's probably NOT 30-40 knots faster.
It's probably a little more efficient and streamlined
as you've noticed below. The problem is, you really
need to compare the planes at identical conditions,
considering altitude, temperature, power settings,
and use TAS and don't bother with GPS Groundspeed.
If you do that, you'll probably find that the RV-10,
while maybe a little faster and more efficient, isn't
really way out there as outstandingly different than
many other high performance planes. There are some,
like the Long-EZ's and others, that may give much
more speed on the same power. The RV-10 isn't that
drastically different.
I can also tell you that while you may be able to
hit 180KTS (KNOTS) at some power setting, you'll
be hard pressed to come anywhere near that on a
cross-country cruise without being willing to pay
maybe double or MORE in fuel than the guy who gets
there about 30 minutes later on the 1000nm trip.
So yeah, while looking at his 180kt GS seemed
to have relevance to the RV-10's Airspeed, there
really isn't anything worth comparing there.
The same concepts should be noted to anyone who wants
to post their RV-10's speed numbers. On the
VAF -10 list you've probably seen the guy claiming
to be much faster than Van's, on a carb engine.
The thing is, there's not any real detail on the
calibration or accuracy of the numbers that's ever
been posted in that case....so there's no way to
tell if it's got any validity to it.
So everyone build your -10, but then fly to
CALIBRATE your readings so you get completely
accurate TAS values, and THEN post the results
at your power setting of choice, including all
Temp, DA, MP, RPM, TAS and other information. Then
you'll have some good numbers. I had to learn this
the hard way, by the way, by posting my numbers
before ever calibrating my stuff. I felt pretty
stupid after that...especially when people
were thinking the numbers were slow, but later
finding out I was actually 6.5-7.5 kts faster.
The -10 should compare very nicely with most
HP planes though.
Tim Olson - RV-10 N104CD - Flying
do not archive
Brian Douglas wrote:
| Quote: |
I went flying with a buddy of mine last week in his 235HP Pathfinder.
On our way back from a $100 pulled pork sandwich, we had the benefit of
a strong tailwind and my friend noted, with some satisfaction, that we
were doing 180knots over the ground. Hmmmm, I thought. An RV-10 with
the same engine would almost fly as fast in a still wind. I should also
point out that my friend's pathfinder has EVERY speed mod you can buy
(gap seals, fancy pants, wing fairings, etc).
So the question is, given the same power and nearly identical
size/weight, how come the -10 is 30-40 knots faster than the cherokee
235? Is the wing just THAT more efficient? Is it the cowl? Flush
rivets? Prop? Combination of all four? Even more surprising is the
fact that you seemingly don't have to pay a price for that speed
advantage. The RV-10 lands shorter, takes off shorter, climbs as fast
and yet has more interior space. Amazing.
-Brian
#40497
N211BD
Iowa City, IA
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GRANSCOTT(at)AOL.COM
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| Posted: Tue Nov 07, 2006 10:09 am Post subject: RV10 vs PA-28-235 |
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Brian I own a 67 235...there's one condition that the 235 beats the pant off of an RV 10...it will haul more weight up in the air...on average 1400lbs...but it's slower for all the items you list...the fat wing is not a true laminar flow wing...under loading it will flex to create more lift loosing it's laminar flow...the cowl is a real speed spoiler along with gear that extends into the sllip stream no matter what pant one uses the tubes are exposed into the slip stream 8-15" above the pant and are uncowled...the plane has many rivets and there is a layer of dome rivets just before the MAC that slows the wing down but allows for more flex and lift.
The wing is basically constant cord with a 2% twist further slowing the wing down but increasing lift. but for all it's hairy warts it's a real beast...is faster than a 182 and will fly about as fast as the Cherokee 6 with a 300 hp engine all the while, sipping 4-5 less gallons per hour. The plane does have a nose heavy feel and will Dutch roll given it's way. But given it's 1960's technology, they are still around whether as a 235 or 236 or the expanded versions, Cherokee 6, 6X, Lance or Toga's are still being made.
If you can find a copy of Flying, August '68 there's a very good articles one on Laminar flow and the second on the Cherokee 235.
Flush riveting and full cowling along with ram airflow will add a lot to tractor engine aircraft...to get even better numbers one needs pusher technology, seamless construction and greater airflow--less resistance...but that potentially may require better piloting techniques/skills over a T-shaped aircraft as well.
Patrick
N9284W
Piper PA 28-235 '67 curises at 130 kts, can fly for 1000 miles and will carry 4 adults with fuel and luggage, hard combination to beat in many GA aircraft.
[quote][b]
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GRANSCOTT(at)aol.com
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| Posted: Tue Nov 07, 2006 10:22 am Post subject: RV10 vs PA-28-235 |
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Tim on the same note as ground speed I've seen our 235 at over 215kts of ground speed on 22" MP and 2200 rpm (CVG to PHL area 2 plus hours on 22 gallons of gas) but I've also seen 85 kts on 2350 squared in cruise. Had a trip last week where we were 195kts ground speed on 21.5" and 2250 rpm's but on the way up we burned the fuel into the wind to visit the Lycoming factory/tour...visiting ERic Parlow and others at Williamsport.
The RV 10's numbers are really very nice numbers but Burt Rutan's designs will beat the 10 in many way's but not in seats per mile...or in ease of construction. I'm looking forward to riding in my buddy Pete's Velosity...but in the time he's spent building the V he could have built 3 RV 10's...but to each there own.
P
[quote][b]
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