N941WR
Legacy Member
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So the 9, with 20hp less, costs the same as the 7. What does the 9 give back in return for that 20ph?
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The -9 is more balanced in its control harmony than the -7.
That is just one reason.
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So the 9, with 20hp less, costs the same as the 7. What does the 9 give back in return for that 20ph?
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The mission: Fly from the Midwest to Alaska and back in an airplane you built yourself.
The first considerations: What airplane, RV7 vs RV9, nose wheel vs tailwheel, c/s vs fixed, carbureted vs injected? If it weren't for Vlad, everyone would say 7 for fuel capacity, c/s for takeoff performance, injected for LOP, and tailwheel for gravel runways. But Vlad is inspiring!
Assume 180hp RV7 or 160hp RV9, no interest in aerobatics, and no interest in aftermarket fuel mods.
This thread, combined with further research here, other sites, Van's, etc., brings me to this summary, as relates to the 3000nm AK trip. Assume two airplanes built per Van's recommendations, i.e., 160hp RV9 and 180hp RV7:
1) 100 mi range advantage 7.
2) 100 ft takeoff/landing distance advantage 9.
3) Cruise speed 10+ knots advantage 7.
4) 8 mph stall speed advantage 9.
5) The prices are almost identical, subject to prop choice.
So the 9, with 20hp less, costs the same as the 7. What does the 9 give back in return for that 20ph?
Because I'm a contrarian, I really want to prefer the 9 taildragger. But this morning's math is providing a hurdle.
Allan, what engine are you using to get that TAS?
... I think there are a few things in this thread that were overlooked and consequently misrepresented. I see these numbers thrown out from Van's website for comparison purposes, and no one has mentioned (or I missed it) the fact that the RV-7 numbers on Van's site were gathered with a C/S prop, and the RV-9 numbers were with a F/P. This really changes the game as in take off and landing distances for one, as well as climb. I have a C/S on my 9 and believe me that is a real game changer. I routinely fly off a 500 ft. strip with obstacles at gross, and have yet to see that from another model. Also comparing the two aircraft at 8000' where the 7s perform there best isn't exactly apples with apples. Me 9-A cruises @ 207 tas. on 7.1 gph. @8000', when up where I usually cruise 14,500 the fuel burn drops to less than 6.5 gph. with no reduction in tas. This reduction also considerably extends the range. Another thing I really like with the 9 series is the rock solid feel at higher altitudes. I fly high (16,500) when winds favor it, and the 9 doesn't even begin to drop its tail and mooch around like models designed to fly at lower altitudes. To me, for what I do the 9s are the best I have seen! The 7s in all fairness do have some advantages, as in aero rating, will fit in a smaller hangar, easier to wash, cheaper to paint, and the #7 just sounds lucky...
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But you won?t find me ignoring the advice from Vans is it? A A pilot of an RV- 9A who is exceeding structural cruise speed, no matter how carefully and skillfully he flies, is not in control of the critical factors and is putting himself and his passengers at risk.
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207 mph TAS is not beyond the Vne of 210 mph TAS. It is close, very very close.
Even at 17.5 the -9 is still flying nose down.
207 mph TAS is not beyond the Vne of 210 mph TAS. It is close, very very close.
Allan must have some tricks up his sleeve because my O-360 powered -9 tail dragger will hit the wall right at 200 MPH / 175 knots, which is just fine by me.
His comments about flying high are right on the mark. Even at 17.5 the -9 is still flying nose down. Whereas the short wing RV's are flying nose up at those altitudes.
Tom wasn't referencing Vne. Max structural cruise speed, Vno, is something different.
The picture you posted earlier in this thread, in post #8, shows this to be false.
Tom wasn't referencing Vne. Max structural cruise speed, Vno, is something different.
The point is that those speeds are getting near the edge for the RV9. ... [/url]
Yep, they are close but not over.
It is up to the pilot to manage the speed. Even an O-235 powered -9(A) can hit those numbers going downhill.
Looks pretty level to me. Besides, the -9 seems to fly more nose down than the short wing RV's. At that altitude, it is still nose down, just not as much as at 8,500'
The PFD does not show any kind of "nose down" indication. And, "Looks pretty level to me" would seem to contradict "it is still nose down".
The two worst turbulence events I have had in my flying career (both while flying RV's at high speed cruise and bad enough to cause major head impact on the canopy even with very tight belts) were surely encounters with wake turbulence, since the air had been glassy smooth for the previous 1/2 hr and it was for the half hour after the event.
That might be because "level flight" is nose down and the EFIS is so calibrated.
The two worst turbulence events I have had in my flying career (both while flying RV's at high speed cruise and bad enough to cause major head impact on the canopy even with very tight belts) were surely encounters with wake turbulence, since the air had been glassy smooth for the previous 1/2 hr and it was for the half hour after the event.
...... then I woke up.
In reality, ive never hit clear-air non-forecasted severe turbulence before but it?s one thing that does keep me up at night. Those are the times you are glad you are operating with lots of margins. By the way, the -9 is better.
The 9 may be better at some things. The amount of margin is not one of them. Not this post, but some of the posts in this thread seem to ignore reality and are trying to operate very near the edge.
Hope the man who over stressed his 9 to 6G had it checked by a competent engineer.
Likely true with some AHRS but the Dynon AD-AHRS must be mounted within 1 degree of all three aircraft axes. (Page 5-9 of the install manual).
And then you can adjust it. Same as a steam gauge.
Question for those that hit the canopy, do you have a 4 or 5 point harness, and how close were you to the canopy, almost 14 mod?
If, by "adjust it", you mean modifying the AD-AHRS mount, that would be true. There is no adjustment otherwise. Why someone would want or need to adjust this in an EFIS is the question in my mind.
Dynon SkyView Manual said:How to Enter the In Flight Setup Menu
When airspeed is greater than zero or groundspeed is greater than 15 knots, simultaneously pressing and holding buttons 7 and 8 when on the Main Menu will open the In Flight Setup Menu. This menu gives users access to SkyView system tools which may be useful during flight such as the Flight Angle Pitch Adjust Page and the Angle of Attack Calibration Wizard.
You may also access the Setup Menu from the In Flight Setup Menu by using the ENTER FULL SCREEN SETUP MENU? option.
...Wow! Its only been about 4 hours since my last post in this thread, and
already I have nine e-mails expressing interest in the belt and harness kit or
mod I talked about. I am saving all the addresses so I can contact all the interested
parties, please keep them coming.
Thanks for your responses. Allan...
I have a lot of your great products, care to share your idea, got us wondering now, are the anchor point geometries inadequate?
It helps if you read the manual:
I have, but you have to stop spending somewhere.In the RV7 vs RV9 debate, have you considered the RV14? It perhaps gives you the best of both worlds?
Question for those that hit the canopy, do you have a 4 or 5 point harness, and how close were you to the canopy, almost 14 mod?
I have, but you have to stop spending somewhere.
I certainly understand that. I am trying to decide between the 7,9, and 14. I am leaning towards the 14, but as of yet, still undecided. It is a large commitment of time and money and I would like to be confident in my decision. And also my wife says I suffer from analysis paralysis, and yep, I believe she is right!
In my case both instances were with a 4 point harness. That is just one of the reasons I am a big advocate of 5 point harnesses in RV's
Adding the 5th point and adjusting its belt properly pretty much eliminates any vertical movement, so short of doing neg. G aerobatics, I don't see why anyone would need to add modifications to the belt system.
BTW, no one should be doing neg G without a secondary belt anyway.
In my case both instances were with a 4 point harness. That is just one of the reasons I am a big advocate of 5 point harnesses in RV's
Adding the 5th point and adjusting its belt properly pretty much eliminates any vertical movement, so short of doing neg. G aerobatics, I don't see why anyone would need to add modifications to the belt system.
BTW, no one should be doing neg G aerobaticswithout a secondary belt anyway.
I certainly understand that. I am trying to decide between the 7,9, and 14. I am leaning towards the 14, but as of yet, still undecided. It is a large commitment of time and money and I would like to be confident in my decision. And also my wife says I suffer from analysis paralysis, and yep, I believe she is right!
In the RV7 vs RV9 debate, have you considered the RV14? It perhaps gives you the best of both worlds?
Staring at the numbers, it's hard to tell what really matters. For instance, baggage. Van's lists the RV9 baggage capacity at 75# and the RV7 at 100#. How can that be, if they have the same fuselage? Perhaps it's a cg thing, assuming a smaller engine in the -9?
100# baggage limit in my RV9A with 1800# gross. CG within Van's specified limits. No realistic way to exceed the CG fore or aft.Staring at the numbers, it's hard to tell what really matters. For instance, baggage. Van's lists the RV9 baggage capacity at 75# and the RV7 at 100#. How can that be, if they have the same fuselage? Perhaps it's a cg thing, assuming a smaller engine in the -9?
100# baggage limit in my RV9A with 1800# gross. CG within Van's specified limits. No realistic way to exceed the CG fore or aft.
It is simply a c.g. thing. Been confirmed through vans multiple times and has been documented in archives here on VAF. My cg with 0320 Catto prop and 4# crush late allows 100# in all configurations.Staring at the numbers, it's hard to tell what really matters. For instance, baggage. Van's lists the RV9 baggage capacity at 75# and the RV7 at 100#. How can that be, if they have the same fuselage? Perhaps it's a cg thing, assuming a smaller engine in the -9?