What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Brake Release to 10000' w/IO360 FP Prop

D

David-aviator

Well Known Member
Not to upstage Rick Galati with his 0320 RV-6A and a time to climb to 8000' (http://www.vansairforce.com/community/showthread.php?t=61723&page=5) I blasted off this morning with the Dynon timer running and 8 minutes and 8 seconds later leveled at 10 grand. Last year it took about 8 plus 20 seconds, the difference this year was no turns, it was straight out.

After take off, rpm was permitted to wind up to 2400 and then set pitch to maintain it. Initial IAS was 120 knots, at 10000' it was back to 95. WOT the whole way.

On the way up it was:

2:12 to 3000'
3:52 to 5000'
5:23 to 7000'
6:18 to 8000' (Rick 7:41)
8:08 to 10000'

Runway elevation 600' so it was a 9400' climb averaging 1165 fpm.

Max CHT 410F, OT 167F, leaned to 1300 EGT. OAT 68F at take off, 46F at 10000.

Estimated gross weight 1515 with 36.4 gallons of fuel on board, 33.7 gallons remaining after landing some 17 minutes later.

As per last year, I issue a challenge to anyone with a CS prop to do likewise just to compare numbers. :)
 
Last edited:
Well, last year I had to do an air test on one of our A330's.

Up to FL350 and back to test EGT probes.

We weighed 155 tonnes at take off. Full power takeoff - 9,000fpm up to FL200 - backed off a bit then.......

Mind you - as a spunky F/O I remember doing an empty takeoff in a 767, we went from the runway to FL430 in around 8 minutes - that was interesting.

Now the Brylcreem Boys can join in with F-14/15/16/18 etc etc tales.

Thought I would get in first.

:D
 
I will take that challenge, although it did take two more cylinders to best your time.
Gross weight 1812pounds
OAT 80.6F ground level, OAT at 10330 66F and 52F at 17,000
I0-540-C4B5 Hartzell BA two blade prop
In this year's AirVenture Cup race I averaged 1580fpm in a climb from 1290asl to 10330 asl. This information was taken from a standing start using my data log. As this was a race I was not interested in the actual best climb rate but also distance covered over the ground. My average IAS for that climb was 133.5 knots.
However my goal was not 10,000 feet but 17,000 in a quest for a bit of tail wind. I averaged 1257fpm for the total climb while maintaining over 130 knots IAS.
I did indeed find a bit of a push and ended up with an average speed of 262 statue mph, 227.8 knots, over the 400 mile race.
I think I will keep my constant speed prop:)
 
Last edited:
mike newall said:
Well, last year I had to do an air test on one of our A330's.

Up to FL350 and back to test EGT probes.

We weighed 155 tonnes at take off. Full power takeoff - 9,000fpm up to FL200 - backed off a bit then.......

Mind you - as a spunky F/O I remember doing an empty takeoff in a 767, we went from the runway to FL430 in around 8 minutes - that was interesting.

Now the Brylcreem Boys can join in with F-14/15/16/18 etc etc tales.

Thought I would get in first.

:D
Click to expand...

Brake release to FL410 in 9+15 out of KAMA on a 90F day a few weeks ago:D

I don't even time it to 10K, because it's less than a minute. :p
 
Buck,

F-15C w/220's clean, FCF...4.5 bills at the end of 12 (12K runway) at VPS. 2.52 on the speed run started at 49K (ish). Personal record. Don't know if I'd drag race a slick Block 50; but we'll have to wait for the Viper mafia to chime in...

Stopped asking for "unrestricted climbs" after the F-22 showed up...what's the point?

All retired now and happy to see 1500 FPM in the mighty RV-4...

Cheers,

Vac
 
Vac said:
Buck,

F-15C w/220's clean, FCF...4.5 bills at the end of 12 (12K runway) at VPS. 2.52 on the speed run started at 49K (ish). Personal record. Don't know if I'd drag race a slick Block 50; but we'll have to wait for the Viper mafia to chime in...

Stopped asking for "unrestricted climbs" after the F-22 showed up...what's the point?

All retired now and happy to see 1500 FPM in the mighty RV-4...

Cheers,

Vac
Click to expand...

less lingo please
 
Yea, I know, the RV time to climb is somewhat of a non event compared to Rockets and jets. But it is fun to see what they can do.

RARE BEAR holds the piston time to climb record to 3000 meters (91.9 seconds) which was set in 1972. I knew Lyle Shelton when he worked for TWA. He once told a story on a flight that the BEAR was tied down with a huge rope. When the engine was all wound up, on signal an assistant chopped the rope with an axe. I kinda doubt that story as I don't see how anyone could stand in the air blast behind that huge 12'+ prop unless he was tied down also. There was no take off roll, Shelton said he just hauled back on the stick and aimed it up.

An original Bearcat set a time to climb record to 10,000' in 1946 (94 seconds). It stood until jets and the BEAR came along.

We have a ways to go with an RV but in its league, it is no slouch. No local spam can, can touch it. :)
 
Let's make this challenge for people who actually have to pay the fuel bill out of their own pocket.
 
Last edited:
Vac said:
Buck,

F-15C w/220's clean, FCF...4.5 bills at the end of 12 (12K runway) at VPS. 2.52 on the speed run started at 49K (ish). Personal record. Don't know if I'd drag race a slick Block 50; but we'll have to wait for the Viper mafia to chime in...

Stopped asking for "unrestricted climbs" after the F-22 showed up...what's the point?

All retired now and happy to see 1500 FPM in the mighty RV-4...

Cheers,

Vac
Click to expand...

That's impressive... Took off from 19 a few weeks ago and could barely get 325 in a -400 Hornet. Although the humidity was like 9 zillion percent on a 101 degree day.
 
10000 takes a little over three minutes for my -6A. Did I mention that I launch at 7000?:p
 
N941WR said:
Let's make this challenge for people who actually have to pay the fuel bill out of their own pocket.
Click to expand...

Oh, good, we're still in the game, then... :D

Vac, I want your MOAs! And you got us beat on top speed, too... Dang.
 
gimp2x said:
less lingo please
Click to expand...

Here is a translation of what he said:
F15 C model with Pratt & Whitney F100-220 engines with no external fuel tanks. From brake release to 450 kias at the end of a 12,000 runway. Mach 2.52 on the high speed run that started at FL 49.5 (usually with a push over and descent to FL 350 (checking for mach idle lock, rudder limiter, trim and engine performance)). He’s not sure he’d win a drag race against the improved block (model) 50 F-16’s…. but they are sure fun to fight. Once the F-22 started showing up, he stopped asking for afterburner climbs…. The F-22 is the new sheriff in town so sense trying to impress the varsity team. He’s now retired with a RV grin flying his RV4.
P.S. At Elmendorf AFB in the winter (really cold) I'd see 430 KIAS at the end of a 7500' runway in a lightweight "A" model.... Oh yeah.....

Bob
Still staring at half done fuel tanks
RV8 slooooo build
N747BM reserved
 
Last edited:
Quick climbs

Bob,
Thanks...you beat me to it.

Vac,
you haven't changed a bit.
 
CLIMB TIME

In the early 90's I had the privilege to FAM on a T-38 out of Williams AFB in PHX. We were on what they called a 'Quicko" route which had us depart RWY 30, make a right turn out and cross the VOR above FL210 on our way (quickly) to FL410. I seem to remember the altimeter making a rev about every 3 seconds as we climbed out. It was very impressive for a piston pilot to see. At altitude we were supersonic for a few seconds. A non event really but fun to say we did it. Like someone said it doesn't really count if someone else is paying the fuel bill.
 
Thread Hijack at M2.5!

As the topic chosen by the originator was "Brake Release to 10000' w/IO360 FP Prop" we seem to have drifted somewhat. But, what the heck, I'll jump in too....

B-744 at 872K, 28C, Brake release to FL100 right at 8.5 min. Cinnamon roll and Starbucks achieved at 4000'/4.6 min:p

If you need verification of the load, one needs only to go to your local Wal-Mart and check the electronics aisle.

My apologies to the thread originator, and it would be great to get additional input, pics, and/or video of our RV's demonstrating their awesome capabilities!

OBTW....The video of the SU-27 is way cool. I am buying my Power Ball tix today!
 
Flight of two RV4's climbing out on a hot day, both with 200HP IO-360's. Mine was FP the other CS. As long as I kept the RPM and climb speeds up, there wasn't much difference in climb rate. But he could bomb around the pattern impressively.
 
A little off-topic, but....

...my Air Tractor weighs 3800# empty and I've flown it at 8500#, on 680 SHP.

Do you jet jocks carry twice your empty weight?

Best,
 
pierre smith said:
...my Air Tractor weighs 3800# empty and I've flown it at 8500#, on 680 SHP.

Do you jet jocks carry twice your empty weight?

Best,
Click to expand...

Pierre,
you left off.....and land on a dirt road to load?
I will always tip my hat (if we could wear them) to you ag guys! I do miss the sound of the big round engines, though.
Best to ya'!
 
pierre smith said:
...my Air Tractor weighs 3800# empty and I've flown it at 8500#, on 680 SHP.

Do you jet jocks carry twice your empty weight?

Best,
Click to expand...

Well - my empty weight is 125 tonnes - my gross weight is 233 tonnes - I can fill to the tanks full with 109 tonnes of fuel so....................

No passengers with full fuel though :cool:

It is fun though playing with a big bird at light weight and getting paid for it - way more cool than the Mil boys but way less cool than the Ag guys... :D
 
Brake Release to 10500' with O-320 CS

Saw your post right after it was posted. Having flown about 1,000 hours with Rosie when he had a 180 FP, I knew that my 160 CS could out climb at 80 KIAS and lower, we were equally matched between 80 and 100 KIAS, and that he could either pull away from or out climb me above 100 KIAS, I figured that my 1961 vintage 5,500+ Hours since new carburetor equipped O-320 160 HP with Constant Speed would not beat your climb time.

Test weight = 1,512 pounds
RV-6 N157GS 13-years since first flight 2,426+ Hobbs Hours

This morning, I departed KCCB (Los Angeles) for KRIU (Sacramento). I knew several years ago, that I could be 10 NM away and at 10,000 MSL 15-minutes after I close my hangar door. There is a mountain peak 10,064 about 10 Nm north of the airport. Cable (KCCB) is 1,444 MSL. Due to noise abatement, departures are a climbing left 270 from runway 24.

4 September 2010 0751 PDT
OAT = 22 C altimeter 29.94
0:00 brake release
1:30 3000 80 KIAS
2:00 3500 OAT = 27 C
2:45 4300
3:24 5000
4:30 6000
5:06 6500
5:41 7000 90 KIAS
6:59 8000 #4 CHT = 427 F OT = 229 F
8:32 9000
9:25 9500 CHT = 413 F OT = 244 F
10:29 10000 100 KIAS
11:29 10500
3 Gallons fuel, 1,250 EGT, 401 CHT, 245 OT, OAT = 15 C OP = 56 psi

The 180 HP out climbs the 160 HP. You win.
 
Break Release to 10,000'

There have been approximately 20 responses to David-aviators original post and the only one that addressed the question he reaised was RV6-flyer's.

As an RV-7 builder nearing completion of the project, I'd appreciate having climb data from other builders to assess my birds performance when I fly it in the next few months.
 
RV6_flyer said:
Saw your post right after it was posted. Having flown about 1,000 hours with Rosie when he had a 180 FP, I knew that my 160 CS could out climb at 80 KIAS and lower, we were equally matched between 80 and 100 KIAS, and that he could either pull away from or out climb me above 100 KIAS, I figured that my 1961 vintage 5,500+ Hours since new carburetor equipped O-320 160 HP with Constant Speed would not beat your climb time.

Test weight = 1,512 pounds
RV-6 N157GS 13-years since first flight 2,426+ Hobbs Hours

This morning, I departed KCCB (Los Angeles) for KRIU (Sacramento). I knew several years ago, that I could be 10 NM away and at 10,000 MSL 15-minutes after I close my hangar door. There is a mountain peak 10,064 about 10 Nm north of the airport. Cable (KCCB) is 1,444 MSL. Due to noise abatement, departures are a climbing left 270 from runway 24.

4 September 2010 0751 PDT
OAT = 22 C altimeter 29.94
0:00 brake release
1:30 3000 80 KIAS
2:00 3500 OAT = 27 C
2:45 4300
3:24 5000
4:30 6000
5:06 6500
5:41 7000 90 KIAS
6:59 8000 #4 CHT = 427 F OT = 229 F
8:32 9000
9:25 9500 CHT = 413 F OT = 244 F
10:29 10000 100 KIAS
11:29 10500
3 Gallons fuel, 1,250 EGT, 401 CHT, 245 OT, OAT = 15 C OP = 56 psi

The 180 HP out climbs the 160 HP. You win.
Click to expand...

Thank you, Gary.

Your old 0320 is doing just fine and I hope the 0360 will do as well when it reaches that age.

We had one other comparison with a 6 cylinder machine and he won hands down. Thanks Tom Martin.

All others pretty well confirm the old adage there's no substitute for HP (or thrust).

We still do not know if a fixed pitch prop is a liability in climb verses a constant speed unit - all else being equal. I am inclined to believe it is not.

Someone prove me wrong. :)
 
David, I fly with CS RVs (180 HP) a lot. They perform far better than my FP prop with 180 HP.

A CS prop performs better than a FP prop. I don't need numbers. I see it often in side by side climbs.
 
Quote:
Originally Posted by gimp2x
less lingo please

Here is a translation of what he said:
F15 C model with Pratt & Whitney F100-220 engines with no external fuel tanks. From brake release to 450 kias at the end of a 12,000 runway. Mach 2.52 on the high speed run that started at FL 49.5 (usually with a push over and descent to FL 350 (checking for mach idle lock, rudder limiter, trim and engine performance)). He?s not sure he?d win a drag race against the improved block (model) 50 F-16?s?. but they are sure fun to fight. Once the F-22 started showing up, he stopped asking for afterburner climbs?. The F-22 is the new sheriff in town so sense trying to impress the varsity team. He?s now retired with a RV grin flying his RV4.
P.S. At Elmendorf AFB in the winter (really cold) I'd see 430 KIAS at the end of a 7500' runway in a lightweight "A" model.... Oh yeah.....


LOL. Why does this post remind me of the scene in "Airplane" where Barbara Billingsly (Leave it to Beaver's mom) translates Kareem's "jive speak"?

Doug
Seattle area
-4, wings
 
Hi Roger..

RogerM said:
........As an RV-7 builder nearing completion of the project, I'd appreciate having climb data from other builders to assess my birds performance when I fly it in the next few months.
Click to expand...

....during transition training my students, I always show them just how good an RV-6 can climb, even at 160 MPH!...over 1000 FPM with my FP Catto three blade, full fuel and two fatties:). Don't get lulled into climbing with a very nose-high climb attitude...it mushes along with those short wings. Check the VSI to really know what your bird's doing. It's a lot more 'solid' at higher speeds, better visibility and cooler CHT's...a win-win situation.

I do the same with my -10...climbs in the 140 MPH neighborhood.

Best,
 
Ron Lee said:
David, I fly with CS RVs (180 HP) a lot. They perform far better than my FP prop with 180 HP.

A CS prop performs better than a FP prop. I don't need numbers. I see it often in side by side climbs.
Click to expand...

Here's the real skinny for what it's worth. A properly designed, high efficiency FP will always have the efficiency edge on a CS because any CS now available will not have as good an efficiency as the FP; a CS has more loss in the root and tip region. In a climb at low speed the CS will always be less efficient than a good FP, but it has the advantage that it can give rated rpm for more power, and it is excess power over what is needed for the drag that is used to climb. Both FP and CS props suffer in a climb from low mass flow due to low forward speed which keeps their efficiency to 75%-80%. If your FP prop at best climb speed turns 2400 rpm vs 2700 rpm rated, your power will be down to 89%. But if you put in a 180 for your 160, you get that back and you will actually climb better than the 160 CS at rated rpm! So, which costs more in the long run? A 160 with a CS or a 180 with an FP, and which has better all-around performance?
 
About climb speeds

pierre smith said:
....during transition training my students, I always show them just how good an RV-6 can climb, even at 160 MPH!...over 1000 FPM with my FP Catto three blade, full fuel and two fatties:). Don't get lulled into climbing with a very nose-high climb attitude...it mushes along with those short wings. Check the VSI to really know what your bird's doing. It's a lot more 'solid' at higher speeds, better visibility and cooler CHT's...a win-win situation.

I do the same with my -10...climbs in the 140 MPH neighborhood.

Best,
Click to expand...

I suspect we are drifting away from the original point of the thread, but this seemed worth a little more discussion.

For non-laminar flow winged airplanes, it is not about the aspect ratio but it is about the drag curve(s). Ellipse's analysis of prop efficiency at climb speeds and angles is good stuff. But whatever engine/prop you are using, you are first controlled by the drag curve and secondly (of perhaps equal or greater effect) by the available power. So here, as a side-benefit of the models I use, is a model of the relevant drag curves which shows where the airplane climbs best as a function of the power-required curve. To make it easy to see, I inverted the numbers so that the light blue curve shows rate of climb, ignoring the power problem that results from prop efficiency and RPM issue.

ClimbGraph.jpg

 
More Fixed Pitch Data

David-aviator said:
On the way up it was:

2:12 to 3000'
3:52 to 5000'
5:23 to 7000'
6:18 to 8000' (Rick 7:41)
8:08 to 10000'

Runway elevation 600' so it was a 9400' climb averaging 1165 fpm.

Estimated gross weight 1515 with 36.4 gallons of fuel on board, 33.7 gallons remaining after landing some 17 minutes later.

As per last year, I issue a challenge to anyone with a CS prop to do likewise just to compare numbers. :)
Click to expand...

Dave, Beat you to 7000, tied to 8000 and then I wimpered out to 10000 ft.

I went out this morning to see what I could do with my IO-360-B2B (180 HP) with a Sensenich cruise prop 72FM8S9-1-85. I tried to replicate what you did. I flew out of Washington MO, straight out on runway 15.
I had about 23 gal gas on board so was around 1426 lb. and density altitude at start was 1000 ft.
Here is the data. As you see from the green curve I started near best rate of climb airspeed but backed off as I was worried about cylinder head temps. Also I really relaxed the stick for the last 1000 ft and my times dropped off (see my airspeed quickly rising). I did no leaning so power (magenta curve) dropped steadily. Should have leaned around 5000 ft. as I went below 75% power.
Climb%2Bto%2B10000%2BMSL.jpg

Pretty good for a cruise FP prop.
 
Last edited:
Phil,

In attempting to read your data and that of H. Evan, I am wondering just what the best rate of climb speed is?

Your data indicates you were closer to that supposed speed, as I started at 120 knots (138 mph) and ended at 95 knots (109 mph). H. Evan's best rate of climb data would indicate I was way over that speed also. Yet, my 8:08 to 10,000' is not all that shabby. It bested your climb by a little, how come?

Perhaps the answer is HP. My engine at 2400 rpm created more power than your engine at 2250. The additional drag of the higher climb speed may be offset by a greater degree by the increased HP than the charts would indicate. Or could it be the theoretical drag vrs AOA data on these airplanes is totally wrong?

The issue of best rate of climb speed with a FP prop is very complex, as Pierre has reported also, and the charted speed of less than 100 mph may not be any where near what it really is.
 
Last edited:
A caution about my chart

As David-Aviator suspects, my chart is highly theoretical. It is just a visualization of known relationships. It is also set up to use 100 mph as the speed for best L/D so that it can be read in percentages. Engine and prop performance vary a great deal in the climb configuration. My chart deals with the airframe only. If you had a rocket motor or anything that had constant THP output, my chart would be pretty accurate.

Unfortunately, the chart (adjusted for my actual Vl/d says my best ROC would be at around 84 mph and the reality is about 121 to 126 mph. That is the way it works with a FP prop. You need those RPMs to get BHP which then translates at some changeable rate to THP. Fly the VSI for ROC.

All this does tell us that the relationship of best L/D to Vx and Vy is probably different for any given two airplanes and any rule of thumb for that is likely inaccurate.
 
There seems to be a lot of interest about ROC, so I thought that I would give the more math-oriented among you of a way to determine the efficiency of your propeller with some simple equations. This will let you know how much of that valuable horsepower your prop is throwing away in a climb.

W=weight,lb, S=span', T=thrust, THP=thrust horsepower, SLHP=rated sea-level HP at rated rpm, EHP=engine power at density altitude. 0.81 or 0.82 is the Oswald efficiency factor of the wingtip.

V=CASmph x 22 / 15 sinGam= ROC / (60 x V) Q=.002377 x V^2 / 2
Ai=(W x cosGam)^2 / (Q^2 x S^2 x pi x 0.81) D=Q x (Ap + Ai)
T=W x sinGam + D THP= T x V /550
EHP= SLHP x (1-6.88E-6 x dalt)^4.756 x rpm/(rated rpm)
Efficiency=THP/ 550 x EHP

Ap for a -6 is about 2.2 and a -6A is about 2.3. The -7 and -7A should be about .066 more based on their extra 11 sq. ft. of wing area, but maybe you can find better info somewhere. This is equivalent parasite drag area which has a Cd of 1.0, not true flat-plate area. As an example, let's use my plane's data. I rounded to one or two places to keep it short.

V=105 x 22 / 15=154; sinGam=1550 / (60 x 154)=0.17, Gam=9.66 deg.
Q=28.19; Ai=(1350 x 0.99)^2 / (794.4 x 24.9^2 x pi x 0.82)=1.40
D=28.19 X (1.5 +1.4)=81.6; T=1350 x 0.99 + 81.6=308.1
THP=308.1 x 154 / 550=86.3;
EHP=125 x (1 + 1000 x 6.88E-6)^4.756 x 2400 / 2800=103.7
Efficiency=86.3 / 103.7=0.832=83.2%
It usually comes out from 82% to 83.6%, which means my prop is throwing away 16% to 18% in a climb.
 
David-aviator said:
In attempting to read your data and that of H. Evan, I am wondering just what the best rate of climb speed is?
Click to expand...
I am as well. I need to go back and look at my Phase 1 test data to see how I calculated Vy of 75 kts that I have in my POH. Quick look at the CAFE report shows they listed a Vy of 87 kts but it came from the builder's POH and not tested in there flights. I do believe that Vy varies with altitude since both drag and thrust vary with altitude. At work we show min time to climb profiles and Mach changes with altitude but there we are going really fast and climbing really high.

David-aviator said:
Perhaps the answer is HP. My engine at 2400 rpm created more power than your engine at 2250. The additional drag of the higher climb speed may be offset by a greater degree by the increased HP than the charts would indicate. Or could it be the theoretical drag vrs AOA data on these airplanes is totally wrong?
Click to expand...
I do not think the answer is HP but prop. I beat your numbers to 5000 ft because I was closer to flying the best rate of climb airspeed. After that (as my speed crept up) your climb was better because your prop is a better climb prop. My Sensenich has 85" of pitch. What does yours have? Maybe some day we need to do a side by side race to see if mine beats you for max cruise speeds.
 
Last edited:
elippse said:
... But if you put in a 180 for your 160, you get that back and you will actually climb better than the 160 CS at rated rpm! So, which costs more in the long run? A 160 with a CS or a 180 with an FP, and which has better all-around performance?
Click to expand...

This is simple. 200HP with a FP! :D
 
Last edited:
Prop Efficiency - another view

While Paul's method for determining prop efficiency is good at the final calculation, I prefer direct measurement of the drag curve to a bunch of factors that may or may not be correct for a given individual airplane. Not right vs. wrong, just a preference for test data over factors wherever possible.

That is why I recommend the methods that are explained in my AirVenture 2010 presentation and in the spreadsheets, all of which you can get to from the links with my signature.

Those methods allow you to measure your airplane's drag and the speed at which it is lowest. You can do them with almost any of the RV's as currently instrumented plus a Garmin 296,296, 496, etc. If you know the CAS and drag at minimum then you can calculated it for any weight, altitude and speed. If you know the drag at a given CAS and you know the TAS at that same point, then you know the THP. Efficiency is THP/BHP. Of course, you are making assumptions about BHP as well, but that's another issue.

My workbooks do all the math for you.

On my main page you will also see an example in the right side section of how prop efficiency can be measured in a C-152. That is one airplane for which we have very, very good data because of Jack Norris and Andy Bauer who, with CAFE, did a propless test of it.

Please keep in mind that it is not always possible to separate engine performance from prop performance. Also be aware that Paul's way and my way are both measuring propulsive efficiency (one definition of it), not pure prop efficiency. That is because there are interactions between the propeller and the airplane behind it. The same prop can give different results on different airplanes because of that.
 
__________________
Just about any calculation you make about performance requires the reliance on all of the test equipment you are going to use to measure the various parameters, and the assumptions you make in their use. The equations I show are the ones that relate to ROC and give a good estimate of your prop's efficiency in a climb. Do you know exactly how much horsepower your engine has at sea-level installed in your plane with your induction and exhaust system? Not unless you have a well-calibrated torque sensor on the prop shaft and an accurate tachometer. Does your engine have exactly the same test set-up that it had at the factory, sans alternator and with stub exhausts? Just about anything you do will be an estimate, but if everyone follows the same method, at least there will be some consistency in the data that results. So I challenge those of you who have done some climb tests and recorded the data to carry out these calculations and see how your prop is doing; you'll get quite a surprise! the majority of you will find that your prop's climb efficiency will be somewhere between 60% and 75%. Go ahead , if you can handle the truth!
 
I accept the challenge

David-aviator said:
Not to upstage Rick Galati with his 0320 RV-6A and a time to climb to 8000' (http://www.vansairforce.com/community/showthread.php?t=61723&page=5) I blasted off this morning with the Dynon timer running and 8 minutes and 8 seconds later leveled at 10 grand. Last year it took about 8 plus 20 seconds, the difference this year was no turns, it was straight out.

After take off, rpm was permitted to wind up to 2400 and then set pitch to maintain it. Initial IAS was 120 knots, at 10000' it was back to 95. WOT the whole way.

On the way up it was:

2:12 to 3000'
3:52 to 5000'
5:23 to 7000'
6:18 to 8000' (Rick 7:41)
8:08 to 10000'

Runway elevation 600' so it was a 9400' climb averaging 1165 fpm.

Max CHT 410F, OT 167F, leaned to 1300 EGT. OAT 68F at take off, 46F at 10000.

Estimated gross weight 1515 with 36.4 gallons of fuel on board, 33.7 gallons remaining after landing some 17 minutes later.

As per last year, I issue a challenge to anyone with a CS prop to do likewise just to compare numbers. :)
Click to expand...

Aircraft: RV-7
Take-off weight: 1575 lbs. estimated
Engine: TMX IO-360 M1B (9:1 pistons - one Slick & one Lightspeed Ign.)
Prop: Hartzell HC-C2YR-1BF/F7497-2
OAT: 27 C AWOS 28 C EFIS
Altimeter: 30.09
Field Elevation: 2187
Density Altitude: 3900 AWOS 3970 EFIS
Wind on Ground: 060 at 11 gusts to 16
I shoved the throttle in, punched the EFIS timer, left the prop knob full in and tried to hold 2600 rpm.
Altitude Time
2187 00:00
3000 1:05
4000 1:50
5000 2:32
6000 3:16
7000 4:03
8000 4:54
9000 5:47
10,000 6:58

Once at 10,000? indicated, I rechecked the AWOS barometric setting, it was unchanged, and I recorded the EFIS density altitude.
I then set the A/P to hold altitude and track and leaned for best TAS. At 2660 RPM and 20.5? MP I was indicating 191 to 193 mph. It wasn?t rough but wasn?t exactly smooth either. Phase one gps testing proved my airspeed indicates 1 mph low at 8000? DA and 187 mph, and is 5 mph slow indicating 199 when I should show 204 mph at 8000? DA, so I should have been up around 198 TAS in reality?
My EFIS temperature probe is in the prop wash. It is located in the wing root cover under the left wing. It is accurate to within one degree of our new AWOS while on the ground but I knew at speed there should be a little induced error. The EFIS temp was indicating 15C at 193 mph EFIS TAS indicated. To test the extent of this temperature error, I tried to hold 10,000? and pulled the throttle back to idle. Not wanting to completely stop the prop, I only got the RPM down to 950 and the airspeed to 70 mph. I flew slow flight there for a few minutes to let things stabilize. The EFIS temp dropped from 15C to 14C. I repeated this 3 times, so I don?t believe there is much more than 2 degrees difference between 200 mph and setting on still on the ground.
Cylinder temps at the top of the climb where; 413, 396, 391, 400. I didn?t record EGT?s but they were in the range of 1305 to 1330. I leaned during the climb beginning at about 5000? indicated but I was not overly aggressive. I have a cowl oil cooler air scoop that feeds my oil cooler ram air and I can vary oil and CHT temps by manipulating this opening. I had it wide open on take-off and max oil temp was 214 at the top of the climb. I started closing it to reduce the lower cowl pressure and get more dp across the cylinders to aid CHT when those temps approached 400 degrees. If I did it again, I would start with it closed. I would also increase my airspeed and let the prop wind up to about 2700 to maximize hp output.
 
Un-Scientific comparison

So far here are the times the best I could compare them. No equations, just raw data (and not really apples to apples). Use it if you think it means anything to you.

Presentation1.jpg
 
Last edited:
Good show, Joe!

But I am not ready to throw in the towel just yet.

Your time to 10,000' started at 2187' above sea level, a climb of 7813'.

If my math isn't faulty, that computes to 1121 FPM.

My time to 10,000' started at 600' above sea level, a climb of 9400'.

Again, if my math isn't faulty, that computes to 1165 FPM.

We are in the same ball park but my homer may have sailed a little further than yours. :)
 
C-130 Numbers

I am no engineer but the wag I have always been told is to subtract 5 knots from your initial climb speed for every 5,000' in the climb. This made me get into my 1-1 (performance manual) and check it out.

I found that for some of the lighter weights (ok I know 130,000lbs does not sound light) the 5 knots is true, the closer you get to max gross weight the less your climb speed is reduced.

Just for the sake of discussion these are the values that I need to enter to come up with a climb speed for a C-130 (yes a prop aircraft):
Gross Weight
Pressure Altitude
Temp Dev from standard
% Power
Drag index (some planes have extra stuff that adds more drag i.e. a 105mm cannon)

Hope this helps.
 
Kilo Charlie said:
I am no engineer but the wag I have always been told is to subtract 5 knots from your initial climb speed for every 5,000' in the climb. This made me get into my 1-1 (performance manual) and check it out.

I found that for some of the lighter weights (ok I know 130,000lbs does not sound light) the 5 knots is true, the closer you get to max gross weight the less your climb speed is reduced.

Just for the sake of discussion these are the values that I need to enter to come up with a climb speed for a C-130 (yes a prop aircraft):
Gross Weight
Pressure Altitude
Temp Dev from standard
% Power
Drag index (some planes have extra stuff that adds more drag i.e. a 105mm cannon)

Hope this helps.
Click to expand...

KC,

From what we read about temps over there, it is probably too hot to build an RV, even the glass work around the canopy.

Good luck and hope you get out of there safe and sound.
 
David-aviator said:
Your time to 10,000' started at 2187' above sea level, a climb of 7813'.
If my math isn't faulty, that computes to 1121 FPM.

My time to 10,000' started at 600' above sea level, a climb of 9400'.
Again, if my math isn't faulty, that computes to 1165 FPM.

We are in the same ball park but my homer may have sailed a little further than yours. :)
Click to expand...
Not sure you can compare those rate of climbs as the ground run becomes a larger percentage of the total climb the higher altitude you start from. We are comparing a lot of different apples here so need to at least keep what we can compare as close to the same as possible.

For the 3K to 10K climb the average ROC numbers are
Dave (180 FP): ROC = 1180 fpm
Gary (160 CS): ROC = 779 fpm
Phil (180 FP): ROC = 983 fpm
Joe (200? CS): ROC = 1190 fpm
 
Absolutely Agree

David-aviator said:
Good show, Joe!

But I am not ready to throw in the towel just yet.

Your time to 10,000' started at 2187' above sea level, a climb of 7813'.

If my math isn't faulty, that computes to 1121 FPM.

My time to 10,000' started at 600' above sea level, a climb of 9400'.

Again, if my math isn't faulty, that computes to 1165 FPM.

We are in the same ball park but my homer may have sailed a little further than yours. :)
Click to expand...

I'm on your side, David! I cheated by starting higher and my math came up the same as yours. But then it was quite a bit hotter during my test, too. I'll leave it to the aerodynamicists to analyze the data. I was just out having fun, trying to add another data point. I learned a bit more about extracting maximum climb performance from the airplane and more importantly from the pilot. I kind of let the airspeed get away from me between 8 and 10,000 ft. For a true test we need to rent an airforce base runway and line everbody up side by side and have a drag race. :) Mattituck says my engine put out 195 hp in the test cell, not 200 FWIW. I'm desperately trying to think up more excuses! I guess my victory rolls afterward were unearned?
 
Caveman said:
I was just out having fun, trying to add another data point. I learned a bit more about extracting maximum climb performance from the airplane and more importantly from the pilot. I kind of let the airspeed get away from me between 8 and 10,000 ft. For a true test we need to rent an airforce base runway and line everbody up side by side and have a drag race. .....I guess my victory rolls afterward were unearned?
Click to expand...

It's all about learning and having fun.
Victory rolls are always earned when flying something you built.
 
Prop full in?

Caveman said:
Prop: Hartzell HC-C2YR-1BF/F7497-2
......left the prop knob full in and tried to hold 2600 rpm.
......I would also increase my airspeed and let the prop wind up to about 2700 to maximize hp output.
Click to expand...

i agree, getting 2700 RPM from a constant speed seems more in line with the spirit of the question raised. Sounds like you might need a governor adjustment (or even a blade stop adjustment), since at WOT, one shouldn't have to do anything other than keep the knob full in to get 2700 rpm. If you find you have to speed up to get 2700 RPM, it doesn't sound like the blades are going fine enough.

Thanks for taking the time to run the test.
 
Here's another one to throw in the mix. Jim Smith's RV-6 with 150HP and a three-blade Elippse prop averaged 916 fpm from 2000' to 10,000' at a constant 95 mph IAS which gives 8:44.
 
unofficial times

I did a test flight this afternoon to check some maintenance work I had just completed. As long as I was flying I decided to give this challenge a try.

Sky was overcast directly over the airport, so I couldn't make a straight climb, however, I did take the data off of my APRS track to see how fast I got to 10k'. My APRS tracking link is in my signature below.

Home Airport: Arlington KAWO
Airport Altitude: 144'
OAT at 144': 64F
Aircraft: RV-7, CS IO-360 with LSE / Slick ign
Fuel: 23 gal

APRS didn't pick me up until I was at 2,562' msl so that's my first data point.

ALT TIME(zulu) Elapsed Time Climb Rate

2562' 00:25:00 0 min 0 sec 0
5292 00:27:29 2 min 29 sec 1,092 fpm avg
9770 00:29:28 4 min 28 sec 1,601 fpm avg
10148 00:30:08 5 min 08 sec 1,487 fpm avg

The first climb rate (from 2500' to 5300') isn't very accurate because I was level flight during part of that time while under the overcast. Climb rate in my RV-7 is around 1,900 fpm at 0 - 3000', 1,500 fpm at 3000 - 6000', 1,200 fpm at 6000 - 8000', and 1000 fpm at 8000 - 10,000'.

I flew most of the climb at 2650 rpm, full rich. Pushed the prop up to 2700 rpm for the last 1000 feet of climb. Max CHT was 415F.

If skies are clear tomorrow, I'll do this again with the timer running instead of using APRS data.
 
LOL! This one is funny. Kinda like the anti brag. <BG> I can beat it though. 747-100 (we were the last ones to park them) Max weight at 36C out of Hong Kong. Brake release to 10K was just over 16 minutes. Timed it on a calendar. ;-)
I think it took us something over a minute and a half to leave the runway, and then we rocketed uphill, sometimes over 600 fpm. <TIC> :) In those old jets, V-R was a spot on the runway, (the end) not a speed...
ah.... good times.


jetjok said:
As the topic chosen by the originator was "Brake Release to 10000' w/IO360 FP Prop" we seem to have drifted somewhat. But, what the heck, I'll jump in too....

B-744 at 872K, 28C, Brake release to FL100 right at 8.5 min. Cinnamon roll and Starbucks achieved at 4000'/4.6 min:p

If you need verification of the load, one needs only to go to your local Wal-Mart and check the electronics aisle.

My apologies to the thread originator, and it would be great to get additional input, pics, and/or video of our RV's demonstrating their awesome capabilities!

OBTW....The video of the SU-27 is way cool. I am buying my Power Ball tix today!
Click to expand...
 
You must log in or register to reply here.
Back
Top