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Great speeds in an RV

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partner14

Member
I was encouraged to post this on Van's Air Force's website, so here goes. After all the terrible weather last week, we needed a window of decent weather to return to Texas from SoCal. We had no idea of just how great the flight would be. Kind of wondering if anyone else has seen these kind of ground sppeds in their RV's. Flying with half throttle, 2,230rpm, climbing at 200fpm, at 15,480', and LOP, we saw . IAS = 154mph, TAS = 198mph, Ground Speed (GPS) = 266kts, or 306mph, wind speed = 110mph.
The second picture taken 72nm earlier shows 301mph, climbing 300fpm, and 8.7gph, which is almost 35mpg.
https://www.facebook.com/photo.php?fbid=3557500467608318&set=pcb.3557530554271976&type=3&__tn__=HH-R&eid=ARChiHpFgvOyTT2DTMlmONLmpDoeN3HwBZa_ebCJrFHy8PeMTFxBwMNSwxrWJ-6q6Z21bv0e_uVSabuQ[/IMG]
https://www.facebook.com/photo.php?fbid=3557507254274306&set=pcb.3557530554271976&type=3&__tn__=HH-R&eid=ARAW_P0xD4pKnYu3G6N3XZBwJrN4ed_Fm7bXWLmLn0G2U0x2nWjRUJHcOfSvgw4-6dTBN8xC4rw7aP9M[/IMG]

Don McDonald 0TX1
RV10 40636 1,100 hours and loving it.
 
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?IAS = 154mph, TAS = 198mph, Ground Speed (GPS) =306mph?


I love it. Were you nervous in the event you hit unexpected turbulence at that speed?
Cheers
 
"IAS is all that matters" when it comes to turbulence penetration speed is what I should say.
 
Turbulence

I guess I could have mentioned that the ride the entire 1044nm was as smooth as silk.... with the exception of the last 800' prior to landing in Texas.
 
I think we need a 300 mph club. My max is 260 mph but I could have been closer to 300 if I had climbed. Yeah, it was smooth in-flight but wicked on the ground.
 
My max GPS ground speed to date is 240 mph. I agree with others that your IAS is all important regarding turbulence but on everything else I LOVE the ground speeds I see in these planes. After all, it IS the number that will tell you exactly when you'll arrive at the destination. I tell my non-aviation passengers that this speed is what you would see on the speedometer if you were driving. Thay can relate and it never fails to impress.
 
Real aviators use knots and NM. :D
While the groundspeed data is reliable, a real measure of performance from the airplane is TAS. Of course PA and engine power have to be factored in.
 
I was happy with my 200kts ground speed in my 6 this week. I was down at 7k and I had to make the return trip in the afternoon. As awesome as 200kts was going, 120 on the way back SUCKED.
 
As far as flying at half throttle.... My engine (IO540) has higher compression and cold air induction, so I pay really close attention to CHT's. Sometimes the temps are fine at WOT, but a higher percentage of the time they're not. You can see the numbers, they're almost perfect.... they wouldn't be if I was WOT. Can't totally tell you why, but after 1,100 hours I have a pretty good handle on what my engine wants and needs. Also I fly by mpg. So even at lower altitudes, if I run several inches less, ususally the mileage is greater. Most pilots don't even mess with the settings, I do. If I gave it those extra 2 inches, sure let's say I pick up from 160kts to 165kts (3% increase), but my fuel burn went from 9.5 to 10.2gph (7.4% increase).
 
Guys please have a read of the article " Flying high and fast" by Ken Krueger, (Google it) makes for some sobering thoughts as a lot of pilots don't understand that VNE at Altitude is NOT based on IAS but TAS.
The Vans designs are very capable of exceeding VNE under certain conditions with fluttering.
Stay safe out there, learn something new everyday -)
 
Latech15 said:
I was happy with my 200kts ground speed in my 6 this week. I was down at 7k and I had to make the return trip in the afternoon. As awesome as 200kts was going, 120 on the way back SUCKED.
Click to expand...
Just think how badly it would suck in a Cessna...
 
partner14 said:
As far as flying at half throttle.... My engine (IO540) has higher compression and cold air induction, so I pay really close attention to CHT's. Sometimes the temps are fine at WOT, but a higher percentage of the time they're not. You can see the numbers, they're almost perfect.... they wouldn't be if I was WOT. Can't totally tell you why, but after 1,100 hours I have a pretty good handle on what my engine wants and needs. Also I fly by mpg. So even at lower altitudes, if I run several inches less, ususally the mileage is greater. Most pilots don't even mess with the settings, I do. If I gave it those extra 2 inches, sure let's say I pick up from 160kts to 165kts (3% increase), but my fuel burn went from 9.5 to 10.2gph (7.4% increase).
Click to expand...

Throttling an engine with the butterfly in the servo results in higher pumping loss than if the engine is free to breath unrestricted. In your example above, why wouldn't you shove the throttle in and grab those two inches of MP, but simply lean back to your 9.5 GPH? All else equal, the engine should produce a bit more power (with less pumping loss), and your CHTs will come down too.
 
Capt said:
Guys please have a read of the article " Flying high and fast" by Ken Krueger, (Google it) makes for some sobering thoughts as a lot of pilots don't understand that VNE at Altitude is NOT based on IAS but TAS.
The Vans designs are very capable of exceeding VNE under certain conditions with fluttering.
Stay safe out there, learn something new everyday -)
Click to expand...

His TAS was well below his Vne, so no issues. Notice he listed both IAS and TAS.
 
To the OP - thanks for sharing in a later post what engine you have. Your initial post made my heart stop. Sure, the ground speed is great because of the wind, but your IAS and TAS would be unheard-of for a normally aspirated 4 cyl Lyc. at "half throttle and 2230 RPM".

And I agree with Toobuilder - as long as you can run smoothly LOP, you should be able to open the throttle and lean the mixture to the same fuel flow, and get the same CHT, and probably go a little bit faster.
 
In response to: Throttling an engine with the butterfly in the servo results in higher pumping loss than if the engine is free to breath unrestricted. In your example above, why wouldn't you shove the throttle in and grab those two inches of MP, but simply lean back to your 9.5 GPH? All else equal, the engine should produce a bit more power (with less pumping loss), and your CHTs will come down too.

Like I said, at times while at wot the temps stay just fine, other times not so much. I continue to lean while watching the cht's, and try to find a spot where everyone is happy. If that doesn't work, pulling back the throttle a little works just fine.
Don
 
this thread should be titled "Great speeds in a Tailwind"... mother Nature helping hand and it ain't really RV related, is it?
:rolleyes:
 
partner14 said:
Like I said, at times while at wot the temps stay just fine, other times not so much. I continue to lean while watching the cht's, and try to find a spot where everyone is happy. If that doesn't work, pulling back the throttle a little works just fine.
Don
Click to expand...

Like a few other posters, I?m scratching my head here, trying to explain how any combination of throttle or mixture could result in ?unhappy? CHTs, at 15K?. Do you have a fixed timing (mag or otherwise) ignition?
 
partner14 said:
As far as flying at half throttle.... My engine (IO540) has higher compression and cold air induction, so I pay really close attention to CHT's. Sometimes the temps are fine at WOT, but a higher percentage of the time they're not. You can see the numbers, they're almost perfect.... they wouldn't be if I was WOT.
Click to expand...

Pics in post 1 don't work for me, so I'll ask...what do you mean by "fine", and "not [fine]", in degrees?
 
Really didn't think about what could happen by posting what I thought was an interesting event due to the wind. So what we have so far is we don't know **** if even some of our instruments have mph. Then I actually used the wrong title, and because the wind was responsible, it wasn't even RV related.
Then even though I was well within the green arc, some think I need remedial training.
I have dual lightspeed electronic ignition. Was told, and later confirmed, that with an RV10 if you have cold air induction and higher compression you will have heat issues. So why can't anyone just believe what a person says about their plane without trying to school them.
I will delete this post. Sorry
 
partner14 said:
Really didn't think about what could happen by posting what I thought was an interesting event due to the wind. So what we have so far is we don't know **** if even some of our instruments have mph. Then I actually used the wrong title, and because the wind was responsible, it wasn't even RV related.
Then even though I was well within the green arc, some think I need remedial training.
I have dual lightspeed electronic ignition. Was told, and later confirmed, that with an RV10 if you have cold air induction and higher compression you will have heat issues. So why can't anyone just believe what a person says about their plane without trying to school them.
I will delete this post. Sorry
Click to expand...

Welcome to the Internet. :(
 
partner14 said:
I was encouraged to post this on Van's Air Force's website, so here goes. After all the terrible weather last week, we needed a window of decent weather to return to Texas from SoCal. We had no idea of just how great the flight would be. Kind of wondering if anyone else has seen these kind of ground sppeds in their RV's. Flying with half throttle, 2,230rpm, climbing at 200fpm, at 15,480', and LOP, we saw . IAS = 154mph, TAS = 198mph, Ground Speed (GPS) = 266kts, or 306mph, wind speed = 110mph.
The second picture taken 72nm earlier shows 301mph, climbing 300fpm, and 8.7gph, which is almost 35mpg.
https://www.facebook.com/photo.php?fbid=3557500467608318&set=pcb.3557530554271976&type=3&__tn__=HH-R&eid=ARChiHpFgvOyTT2DTMlmONLmpDoeN3HwBZa_ebCJrFHy8PeMTFxBwMNSwxrWJ-6q6Z21bv0e_uVSabuQ[/IMG]
https://www.facebook.com/photo.php?fbid=3557507254274306&set=pcb.3557530554271976&type=3&__tn__=HH-R&eid=ARAW_P0xD4pKnYu3G6N3XZBwJrN4ed_Fm7bXWLmLn0G2U0x2nWjRUJHcOfSvgw4-6dTBN8xC4rw7aP9M[/IMG]

Don McDonald 0TX1
RV10 40636 1,100 hours and loving it.
Click to expand...

Great write up Don thanks for sharing. Nice work There is no need to delete your post, I think the majority of us really enjoyed and learned from it.
 
partner14 said:
Really didn't think about what could happen by posting what I thought was an interesting event due to the wind. So what we have so far is we don't know **** if even some of our instruments have mph. Then I actually used the wrong title, and because the wind was responsible, it wasn't even RV related.
Then even though I was well within the green arc, some think I need remedial training.
I have dual lightspeed electronic ignition. Was told, and later confirmed, that with an RV10 if you have cold air induction and higher compression you will have heat issues. So why can't anyone just believe what a person says about their plane without trying to school them.
I will delete this post. Sorry
Click to expand...

I found your post interesting. It is nice getting a strong tailwind especially if it is smooth. Airguy is right. Welcome to the Internet. An unfortunate byproduct of some forums.

Jim
 
N941WR said:
His TAS was well below his Vne, so no issues. Notice he listed both IAS and TAS.
Click to expand...

I never said this guy was near VNE, you missed my point! It's the misconception that some think that being in the green arc all is good at high Alt! Often not so!
 
partner14 said:
... So why can't anyone just believe what a person says about their plane without trying to school them...
Click to expand...

Probably because this forum spends a lot of time debating high CHT, running LOP, TAS/flutter, and ignition timing. These are hot button issues and you touched ALL of them in your first post. Welcome to the internet.

No offense intended, but many of us have been down this road and overcome the "problems" you are having with your bird. Most of us are here to help if you want it.
 
Flying from SEA-RDD-PHX (about 1200 miles). A cold front approaching south bound my record RV4, 150HP O320 with constant speed prop. Alt mid teens and en-route GS average over half the trip was +270 MPH. I forgot MAP and fuel flow but I was below 55% power.

My RV-4 had a no-wind no-reserve econ range was about 800 miles at 55%. Route from SEA to PHX direct is about 1100 miles total but typically flew SEA-RDD-PHX. One fuel stop was always needed. However this day I was showing over RDD enough fuel to make PHX area (no reserves). I ending up making my first fuel stop 300 miles past RDD to BIH, Bishop CA a great fuel stop, a gas pump in the sky at +4000 feet. Highly recommend it. Less descent and climb to get back en-route. I thought about adding AUX fuel after that, to make one leg trips between SEA and PHX. I never did, but then again how often to you get +80MPH tail winds.
 
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In regards to Latech15 post about 120 on the way back. I once flew the RV to SunNFun with a very nice tailwind yielding max speeds of 229 mph across the ground. On the return trip home I was 130 most all the way. I actually felt I was NEVER going to make it home. Many years ago I flew my good ol cessna 152 from South Alabama to Norfolk, Virginia to visit my son when he was in the navy. My max GS going up and coming back was 130 mph. I actually had this thought... "I can see how guys get hooked on this speed stuff!"

It's all a matter of perspective. :)
 
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partner14 said:
I have dual lightspeed electronic ignition. Was told, and later confirmed, that with an RV10 if you have cold air induction and higher compression you will have heat issues. So why can't anyone just believe what a person says about their plane without trying to school them.
Click to expand...

Because perhaps you were told wrong? Maybe you should be able to run full power without having a temperature problem? Might be something others have been through and solved, and you could, too?

An awful lot of RVs with all sorts of configurations out there flying around not having cooling problems.

But again, to start with a *basic* question...what CHTs do you see, and what do you consider to be "too high"? What does the engine manual say is allowable?

A lot of people get panicky when they see a CHT above some value which is WAAAAY below what the engine manual says is allowable. I know some guys who insist on keeping them below 380, or even 360, at all times, despite what the manual says. (THAT should open the flame wars here :) ).

So what are yours?
 
Flew into Buckeye, west of Phoenix to visit an old friend of my wifes. That evening all **** broke loose. Haboob is what they call it. Long story short... went out to airport, turned plane around. Noticed damage to rudder. Next morning flew non-stop to 0tx1, and landed with approx 9 gallons remaining. That's the fathest I've flown non-stop. (758nm, 872sm). Then after contacting the insurance company, they paid me to build a new rudder.
Don
 
I like to keep the CHT's in cruise below 400. If they creep a little iver that in a climb I don't worry too much. But the numbers you see on the AFS for #5 and #6 of 377 and 379 are numbers I'm happy with.
 
partner14 said:
I like to keep the CHT's in cruise below 400. If they creep a little iver that in a climb I don't worry too much. But the numbers you see on the AFS for #5 and #6 of 377 and 379 are numbers I'm happy with.
Click to expand...

That's fine, nothing wrong with those temps.
 
partner14 said:
I like to keep the CHT's in cruise below 400. If they creep a little iver that in a climb I don't worry too much. But the numbers you see on the AFS for #5 and #6 of 377 and 379 are numbers I'm happy with.
Click to expand...

And what do you see WOT at a comparable altitude? (ROP vs LOP is important to know, as well).
 
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