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How High......?

mike newall

Well Known Member
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Quick bit of fun.

Got bored on a beautiful fall afternoon and thought - Hmmmm, how high.

Still climbing at 500fpm as we got to 15,000' in a 180hp, MT c/s RV7, 2 up, after lunch :rolleyes:

As per old skydive techniques, brought speed back a couple of knots a thousand after 5k to allow for IAS etc etc. Ended up showing 90kts at 15k minus 7c truing a lot faster :D

Took some snaps, then set off back down at 170kts and 20/23 to keep things warm.

A good grin.

So - who has been higher in a stock aeroplane ?
 
My feeble memory says someone (possibly Dan C) searched for the service cieling in a 200 hp RV7 about 10 years ago. It was in the 23000 ish region but that memory could certainly be off.

I have been to 18000 myself (180 hp) a few years ago due to some awful weather on the US east coast and the bird was a bit sluggish but not terribly so.
 
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Quick bit of fun.

Got bored on a beautiful fall afternoon and thought - Hmmmm, how high.

Still climbing at 500fpm as we got to 15,000' in a 180hp, MT c/s RV7, 2 up, after lunch :rolleyes:

As per old skydive techniques, brought speed back a couple of knots a thousand after 5k to allow for IAS etc etc. Ended up showing 90kts at 15k minus 7c truing a lot faster :D

Took some snaps, then set off back down at 170kts and 20/23 to keep things warm.

A good grin.

So - who has been higher in a stock aeroplane ?

Much higher. :)

Account of Terry Jantzi's flight to 25,900' in his RV-6 back in 1999:

http://home.hiwaay.net/~sbuc/journal/high.html
 
Too many flights to remember have been at 14,500 on cross country trips. My plane loves it. I have not been higher but given the way the plane performs, I would expect it can go much higher.
 
favorite altitudes

Not exactly to your question, but in my -4 I preferred to fly it between 10 and 12 thousand feet most of the time. There really are very few spam cans at that altitude, gallons per hour around 7-8, and I like to listen to XM radio. No need to talk to ATC and I fly right over most class B airspace. YMMV

Oh, And I use oxygen. Amazing how well you feel on arrival.
Ron
 
Not exactly to your question, but in my -4 I preferred to fly it between 10 and 12 thousand feet most of the time. There really are very few spam cans at that altitude, gallons per hour around 7-8, and I like to listen to XM radio. No need to talk to ATC and I fly right over most class B airspace. YMMV

Oh, And I use oxygen. Amazing how well you feel on arrival.
Ron

I tend to fly here as well. I would like to go higher to save fuel, but my 320 just doesn't like to climb that high. By 12K, my climb is below 400 FPM and my patience runs out.

Larry
 
Redlines at various altitudes. Pick the Vne applicable to your Model.

i-wLv7VKD-M.jpg

Perfect.......

We were in by 2.4kts as we passed 10k - took a while to accelerate ;)


We have controlled airspace above 18k so may have a go at that sometime. Will need to 'borrow' a portable O2 bottle from work.
 
3 blade at 17.5k

I have some plans with a flying buddy to retest with his 2 blade Hartz but I did a quick run last week to the top of VFR (RV-7 IO-360 3-blade MT no passenger)

16k5 to 17k5 vspeed 320fps @ 110 IAS

17k5 5.9gph (LOP) 158 TAS*
17k5 6.9gph (ROP) 169 TAS*

All I can say is I am no longer worried about flying at that altitude, everything about flying the plane is still comfortable at 17K5 except perhaps the view and fixating on your Oxygen levels :p



*One direction run only
 
Why would VNE follow TAS and not IAS? IAS is what the airplane 'sees', not TAS.. What am I missing?
I am afraid you have that backwards. True airspeed is the "TRUE" speed of the air flowing across your wings taking into account air pressure and temperature. Indicated air speed is a derived speed based on mathematical formulation of "INDICATED" readings from the mechanical movement or flow of electrons in an instrument.
 
Why would VNE follow TAS and not IAS? IAS is what the airplane 'sees', not TAS.. What am I missing?

Aeroelastic flutter. It doesn't care one bit about IAS.

As for height - I routinely cruise VFR 16,500 and 17,500 on my cross-countries, and usually am still climbing 400-500 fpm when I level out there. Once I finish my IFR ticket I'll venture higher in search of the true ceiling for my plane.
 
Pilot's shouldn't have to think in terms of TAS while flying. I think that Van's should state their Vne (Redline) in terms of IAS (or CAS) as a function of altitude, up to the service ceiling of the airplane. Builders may even want to mark their airspeed indicators accordingly.

+1
This would bring RV?s markings into conformance with normal catagory aircaft.
 
Density altitude has to be very high, maybe Leadville Co., for TAS and indicated to diverge very much at low speeds like approuch speeds. Besides, by the time on on short final I'm flying by feel and attitude anyway.
 
+1
This would bring RV?s markings into conformance with normal catagory aircaft.

There is nothing stopping you from putting the red line on your airspeed indicator wherever you want it instead of where Van's suggested. But I bet you haven't done it...
 
cruising and then it all fell apart

a couple years ago.....20k and +200 kts. then I became loopy and shut off my avionics master and began staring into my black dynon screen wondering what happened..... at least I had enough sense remaining to spiral down thru the rain. but Vlad does this stuff all the time and makes me think round steam gauges may be better (or maybe Russians are a superior species?). or maybe my plane just wanted to go to Huntsville and spend the night.

track_zpsmprl7amx.png
 
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Whenever the topic of "how high have you been in your RV" comes up, I'm always reminded of what Bruce Bohannon accomplished in 2006 with his modified RV-4; ...47,500'.
 
There is nothing stopping you from putting the red line on your airspeed indicator wherever you want it instead of where Van's suggested. But I bet you haven't done it...

As a matter of fact my GRT HX EFIS has an option for inputting red line in TAS, so it automatically moves down on the IAS tape as altitude goes up. But not everyone has this option.
 
Density altitude has to be very high, maybe Leadville Co., for TAS and indicated to diverge very much at low speeds like approuch speeds. Besides, by the time on on short final I'm flying by feel and attitude anyway.

Maybe not as high as you think. I live near sea level, but only 30 minutes away are short fields at 3000?. In the summer(90 F) 65 KIAS calls for 70 KTAS. And 45 minutes away is South Lake Tahoe, where IAS and TAS differ by 10 knots in the summer.
 
As a matter of fact my GRT HX EFIS has an option for inputting red line in TAS, so it automatically moves down on the IAS tape as altitude goes up. But not everyone has this option.

But for everyone else they should live with a lower performance limit? I.e. an RV-9's redline at 15,000' is 145kts IAS. It can easily and safely exceed that at 3500', but your suggestion would arbitrarily limit it to something much slower.

I think Van's approach is correct, and fortunately there is little chance that it would change. It requires pilots to be aware of the limitations of their aircraft, but isn't that required any way?
 
Quick bit of fun.

Got bored on a beautiful fall afternoon and thought - Hmmmm, how high.

So - who has been higher in a stock aeroplane ?

Went to 45,000' in stock F-86 about 60 years ago....yea, I know that's not fair. :)

Have been up in your territory but not long, it got cold.

Another thing that's fun is a WOT climb to 10,000 from take off. Have done it in less than 9 minutes with FP Catto.
 
14,000 feet in my RV12. Not legal you say. Believe it was. 2000 feet over a 12,000 ft mountain.

I think you may be confusing the altitude limit. If you are a sport-pilot, then what you say is true. But it has nothing to do with the RV-12.

10,000' altitude is a pilot limitation, not an LSA limit.
 
Bob Turner and RV8JD, you are correct regarding IAS. I overstated what I always use. Good reminder that straight and level stall occurs at about the same IAS as altitude increases
 
Us too.

We have test flown up to class A, but not above with our little 8. The aircraft has very good handling and is comfortable to fly with a good reserve of power and climb at that D.A. and level. In one flight the D.A. was about 1,500' higher, so we think that is enough testing for this one. The only comment I think, would be a personal note. I have always like 13,000' for long C.X. flights if the winds up there are good to us. If we wanted to go to the east cost from our place in TEXAS we would want to go high as it is common to see winds at 9K to 15K 30-40 Kts. blowing mostly out of the west. But the flip side is we need to go low, down at 3,000" going west. 13,000 has worked good for me as I still have 92-94% O2 saturation up there and am close to the O2 ceiling as well. This level is not for every one and an O2 bottle if you need it is a good thing. If I remember correct most of the airliners, not all of them have a cabin pressure of 8,000' as a setting. After testing I have no reservation that our little 8 with an IO-360 and a good Prince P tip will go up to Van's service ceiling and then a little more as the book states a 100"/min. climb from that set point. As has been covered above be careful up there as thing to go fast in a hurry when you start down from up there. Plan you decent carefully and keep your speed in check. It is better to see everyone come home safe and have fun at the same time.
Yours, R.E.A. III # 80888
 
But for everyone else they should live with a lower performance limit? I.e. an RV-9's redline at 15,000' is 145kts IAS. It can easily and safely exceed that at 3500', but your suggestion would arbitrarily limit it to something much slower.
?

I think you mis-read my comment to a post. The FARs for standard catagory aitcraft require Vne in IAS; but a placard of different values as a function of altitude is allowed. Nothing changes except the presentation. Is that needed? Well, there sure seems to be a lot of confusion over this. Conforming to the usual presentation standard can?t hurt.
 
13,000 has worked good for me as I still have 92-94% O2 saturation up there and am close to the O2 ceiling as well. This level is not for every one and an O2 bottle if you need it is a good thing.
88

If you?re up there more than 30 minutes, then legally you?re over the ?O2 ceiling?.
 
ChiefPilot, if you look at the links in my post #16 of this thread, you can see how other manufacturers handle the issue. They just don't state the Vne in terms of TAS, they give it in IAS/CAS as a function of altitude.

Like Bob said, there is some confusion among RV pilots on the issue.

Hope this helps.

No, I totally get it - a chart like you provided is pretty common in sailplanes. I understood Bob's post to be that Van should publish Vne as a single IAS airspeed as many/most brand B/C/P piston singles to.

If the suggestion is to supply a chart, great - you've done just that above so we're all good...right?
 
I am afraid you have that backwards. True airspeed is the "TRUE" speed of the air flowing across your wings taking into account air pressure and temperature. Indicated air speed is a derived speed based on mathematical formulation of "INDICATED" readings from the mechanical movement or flow of electrons in an instrument.

OK.. did some more reading on the subject..

Apparently the main reason for VNE limitation is a flutter issue, and flutter is apparently caused by the speed of molecules over the surfaces, not the number of them.. So I guess that makes sense.
 
OK.. did some more reading on the subject..

Apparently the main reason for VNE limitation is a flutter issue, and flutter is apparently caused by the speed of molecules over the surfaces, not the number of them.. So I guess that makes sense.

Truth is, it?s complicated. There are exciting forces, and damping forces. There are different flutter modes: ailerons flapping, elevator flapping, trim tab flapping, entire empenage flapping, wing twisting, etc. For some modes the critical number may be some V (true airspeed). For other modes the critical parameter may be the square root of density times V (indicated airspeed). And for some other modes the critical parameter may be the product of density times V (not described by any single common parameter). Specifying Vne in terms of True airspeed tends to be the most conservative route.
 
Went to 45,000' in stock F-86 about 60 years ago....yea, I know that's not fair. :)

Have been up in your territory but not long, it got cold.

Another thing that's fun is a WOT climb to 10,000 from take off. Have done it in less than 9 minutes with FP Catto.
:rolleyes:


Brakes off to FL430 in a 767 in 8 mins was fun......

So was 9'000 fpm in an empty A330

Happy days and simple pleasures - eh :rolleyes:
 
If you?re up there more than 30 minutes, then legally you?re over the ?O2 ceiling?.

Yep, that is true, That is why I put the close in there some where. You have a good point and it is one that is not right for everyone. And I do not recommend it to anyone. And if I am VFR, I am not supposed to be there anyway. But I will be close if I have a good day and fair winds aloft.
Thanks, Yours as always, R.E.A. III # 80888
 
Interesting discussion about the VNE. But I would like to point out something else to consider while flying at this altitudes. I worked on the Solarimpulse project and we used the same avionics and autopilots as a lot of us RV pilots do. When the aircraft flew the first time above FL240, the capacitors in the autopilot-servos expanded up to the point where the servos failed. We had to replace those capacitors as the airplane had a designed cruise altitude of max. FL280.

So before you go up to those altitudes be sure you have a properly working oxygen system (the time of useful consciousness gets very small up there) and check that all your systems work at those altitudes.
 
Yup, we're good. All we are saying is that Van's should publish Vne in IAS as a function of altitude, because IAS is what pilots refer to when flying the airplane.
I am sorry but I cannot agree with this statement. Yes, it is true that, historically, pilots used an Indicated Air Speed (IAS) instrument as the only means to measure airspeed. However, there is a reason for that. That was the only instrument available to measure airspeed for a pilot in the past. Today, we no longer need to be performing mental mathematical gymnastics while flying to know what TAS is. For many of us pilots who have chosen to utilize new instrumentation in place of old traditional round dial guages, we have all manner of instrumentation to tell us the various measures of airspeed simply by looking at the instrument.

So, since aerodynamic flutter is a serious issue that is observed by knowing what true speed the air is flowing across the structure, and we pilots now have tools to always know what that true airspeed is, why would we not want to use that information rather than continue trying to understand a whole lot of calculations and conversions just so we can continue using an old system we no longer need to rely on?

I am one pilot who does NOT refer to IAS when flying the airplane. With one exception. I do rely on IAS when landing, as that IAS gives me the best information as I get closer to the stall. So because of that please don't think I am saying we should not use IAS. Just saying use the hammer on a nail. Use the screwdriver on a screw.
 
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RV8JD; said:
Note that even Cessna states Vne in IAS & CAS for their 300/400 series (derived from the Columbia 300/400). And they don't have round dials.
Arguably, I would not consider that a very strong argument for why it should be done that way. A long established company has quite a few motivations to keep doing things the same 'ol way' that have little to do with what 'is best'.

RV8JD; said:
And I will humbly suggest that is not good piloting practice. As I'm sure you're aware, all airplane performance numbers and structural speed limits (with the exception of flutter) are governed by Calibrated Airspeed (CAS), not True Airspeed (TAS). The only item where TAS comes into play is flutter.

(P.S. I'm a flutter guy, and know a little bit about the "F" word! :D
Since you are clearly interested in making sure we all understand your point, I think it only fair that I reply in kind. I was making the point that I use TAS speed where it appropriate. Like avoiding flutter. Which is why I do NOT use IAS in a regime where avoiding flutter is important. And using IAS when landing. I only mentioned landing and stall speed simply for brevity's sake. I do not just rely on IAS for stall avoidance. There is Vf, Vy, Vx, Va, etc., yep, use IAS for them.

I was hopeful that my point of using the appropriate tool for the appropriate job is what we all should be doing. Speaking of which, I also have that wonderful tool, Angle Of Attack, I use to guide me in that stall avoidance regime.

Lastly, I must end my comments with the most important point of all:
Live Long And Prosper!
 
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