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Climb numbers

RV7Guy

Well Known Member
I'm trying to get a cross section of realistic climb numbers for a dillusional friend. (He's the guy building what he believes will be the lightest RV7) He believes if his 7 is around a 1000 lbs with 180hp IO360 that he will be able to achieve 2500 to 3000 fpm. I know, I know, stop laughing.

So if you could, your plane, engine/prop, weight, AS used for climb, your field elevation and rate of climb.

Thanks in advance. Others might be interested in this as a good baseline of performance.
 
climb

I had a fixed pitch climb prop on my RV8A O-360 180hp wt 1086lbs empty and easily saw 3000fpm. I dropped to 2000fpm with the cruise prop but my cruise speeds jumped to 165 kts TAS. I would think the -7 would be similar.
 
Include altitude in your posts

Not to hijack this thread, but...

I've been going back and forth between a FP and CS prop. I really like the Catto three blade option. I really don't care about 3-5% delta in cruise (I'm going to set 75% power anyway), but I do care about climb performance, as I fly out of an airfield in Colorado that is at ~5000' I've already read all the FP vs CS rants, er I mean posts.

My only request here is that when you post your climb numbers, include altitude starting from and engine/prop combination.

Thanks,

Beer30?
 
LOL
I know a guy who thinks he is a test pilot cause he built an RV4. Claims 3500+ climb rate @ 1000 feet. I said no way, how are you determining ROC? He says easy, I lower the nose to vne and then pull up. Best I've seen is 3625. Wrong in so many ways.
 
Doing some math

I'm trying to get a cross section of realistic climb numbers for a dillusional friend. (He's the guy building what he believes will be the lightest RV7) He believes if his 7 is around a 1000 lbs with 180hp IO360 that he will be able to achieve 2500 to 3000 fpm. I know, I know, stop laughing.

So if you could, your plane, engine/prop, weight, AS used for climb, your field elevation and rate of climb.

Thanks in advance. Others might be interested in this as a good baseline of performance.

A 1000 pound airplane (not a good number for RV-7 plus fuel plus pilot) and a 3000 fpm climb requires: 1000 x 3000 / 33000 = 90.91 excess THP. My 7-A requires approximately 43 THP at speed for best L/D or 34 THP at the speed for minimum sink. The speed for minimum sink is theoretically the best rate of climb speed but due to prop issues that's rarely the case. Thus the total THP required for this fictional aircraft would be at least 125 and as much as 134. To compute BHP we need to take account of the prop. Since this is a regime where prop efficiency is low, let's use an overly optimistic 80%. That means that the BHP would need to be 156 through 168, more or less. OK, that works out. The lighter airplane would use less HP than mine.

Now lets add the pilot and the fuel, about 300 pounds. Now it is 1300 x 3000 / 33000 = 118 THP for climb. Use 34 THP for minimum sink and you have 152 which requires, at 80% prop, 190 BHP.

He's going to need to do a lot to achieve his goal. My plane won't even come close because of the Catto cruise prop.
 
VSIs often have quite a bit of error. If your friend tries a few different VSIs, he can probably find one that will indicate more than 3000 ft/mn in a stabilized climb. But, if he uses the altimeter and stop watch as his measure of climb rate he will have some difficultly in achieving his goal under standard conditions.

He may be able to get altimeter and stop watch to show more than 3000 ft/mn on cold winter days in Minnesota though, but that is largely because the barometric altitudes are closer together in cold temperatures. E.g, if it is -15 deg F at 2000 ft and you climb for 1000 ft change in barometric altitude, you have only really climbed 870 ft. So, if your altimeter and stop watch said you were climbing at 3000 ft/mn, you would really only be climbing at 2600 ft/mn. The engine makes more power when the air is cold, which helps too. But, I see you are in AZ. Tell your friend it is hopeless.

Edit - Hmm - Now I see that the bottom end of his target is 2500 ft/mn, not 3000 ft/mn. He might possibly be able to do that, if he had a prop that was optimized to give its best efficiency at low speed. Most props that RVers use are optimized for higher TAS, so the prop efficiency falls off at slow speed (the optimum twist angle in the blade varies with TAS). But if he is prepared to give up some cruise speed, he should be able to get 2500 ft/mn. But, given that he'll spend a lot more time in cruise than he will in climb, he'll probably want a prop that is optimized for cruise.
 
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Not to hijack this thread, but...

I've been going back and forth between a FP and CS prop. I really like the Catto three blade option. I really don't care about 3-5% delta in cruise (I'm going to set 75% power anyway), but I do care about climb performance, as I fly out of an airfield in Colorado that is at ~5000' I've already read all the FP vs CS rants, er I mean posts.

My only request here is that when you post your climb numbers, include altitude starting from and engine/prop combination.
he,he..........

I'd rather have a more comfortable plane, than a high climb rate. Afterall, what's the point? :D

Do you climb fast to get to efficient altitudes for long cross countries; only to feel like you're compromising the feel of comfort? :) :eek:

My plane is a "heavy weight"! 1172 lbs. But it does include leather seats, a C/S prop, the older heavy starter motor, and oxygen tank, as well as two radios, 2 axis A/P and audio panel. Yet it's more nimble than the 9's I fly with, and has a sports car feel. And it gets off the ground much sooner and higher, than all those fixed pitch planes I see. We were at a recent fly in (5637 elevation & hot); and it was very noticeable if the RV's taking off, had a fixed pitch or C/S prop. Really!!! :D

So throw in the leather, the C/S, and be much happier in the long run! :D

L.Adamson --- RV6A (flying)
 
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3000 fpm to where?

The only way to measure rate of climb is with a timer - starting at brake release and take it up to 10,000'. First guy up there is the winner!! That's how you set climb records. I have not done it with this airplane but I would guess it will make it in about 8 minutes - depending on OAT, fuel load and all the rest of the variables.
 
Measuring rate of climb

Kevin and David are both correct of course, but a Garmin handheld will give you an accurate rate of climb to 4 significant digits.
 
David, I fly out of an airport at 6800' (00V). My Catto does fine BUT all the CS prop guys outclimb me every time.

I fly out of Leadville fine but the CS RVs do better.

My rant suggestion: CS if you can.
 
David, I fly out of an airport at 6800' (00V). My Catto does fine BUT all the CS prop guys outclimb me every time.

I fly out of Leadville fine but the CS RVs do better.

My rant suggestion: CS if you can.

Absolutely no argument with that statement. I miss the MT7. It hauled butt big time on take off. But for $2200, you can not beat a Catto.
 
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More info

I should have mentioned that he is going have a WW200RV prop. He wants to set a record for 10000ft climb and reach 26,000 ft. He is only going to have a radio, transponder and AFS3500 in the panel. He is going to try to get a waiver for the 26K effort. No lighting of any type. He will not even put in anti-collision lights because of the weight. FYI, my 7 weighs 1123.

When he is done with the plane I told him we'll do a head to head flight from Chandler AZ to Big Bear CA. While he hand flying and adding miles to the trip, I'll be kicked back with the AP on and listening to tunes on the XM.
 
To each his own...

I should have mentioned that he is going have a WW200RV prop. He wants to set a record for 10000ft climb and reach 26,000 ft. He is only going to have a radio, transponder and AFS3500 in the panel. He is going to try to get a waiver for the 26K effort. No lighting of any type. He will not even put in anti-collision lights because of the weight. FYI, my 7 weighs 1123.

When he is done with the plane I told him we'll do a head to head flight from Chandler AZ to Big Bear CA. While he hand flying and adding miles to the trip, I'll be kicked back with the AP on and listening to tunes on the XM.

To each his own, but FL260 in a stubby-winged RV is not a good time. Going to Big Bear is a good time. I trust that your friend has a full understanding of the realities of high altitude, oxygen, and something really warm to wear. :rolleyes:

John Clark
RV8 N18U "Sunshine"
KSBA
 
RV Climb Peformance

Darwin,

My RV-4 has a parallel-valve IO-360 with 9:1 pistons and the older Hartzell CSP. Weight is less than 1000 lbs.

I have the RMI microencoder and my VS function is set to display a 10 sec moving average.

Stabilized at best climb of around 100 KIAS, I see 1900-2100 fpm when climbing from the KDVT field elevation of 1500 MSL to 2500 MSL.

If the goal is to modify an RV for best climb performance, the result will be something like Bruce Bohannons' Flyin' Tiger - Is your friend aware of that aircraft?

Certainly good to keep an aircraft light - what is the lightest RV-7 built so far?

Regards,
Blake
 
I'm flying a 6A with a built IO360, that was measured at 195BHP. I've got a CSP. I've seen the climb indicator reach 3000fpm a couple of times. 2000-2500 is plenty feasable, though for cooling I lower the nose. For wear and tear...and to keep the airport neighbors happy....I pull power back at ~500 AGL, to 22"MP when solo (airport elevation is 650'), and I'm slowly dialing the prop back to 2400RPM....which generally has me at ~800'AGL at that point....where if I'm staying in the pattern, I'm on crosswind and pulling MP back to 19" then 15".

The -6 with 180hp+ & CSP is a rocket. Especially solo with half tanks. I can't barely get all the power in before its time to pull it back.

I'm sure others here have similar experiences. I only have about 20 hours in the -6A....so mostly I read a lot on this forum. But these are my experiences so far. I'm very impressed with the -6A.
 
We're at 328' ASL

....and I usually see 1800 FPM solo in coolish weather. The FP Catto is set up for cruise. Two aboard, around 1500-1700 FPM at 130 MPH. 160 MPH still gets me around 1100-1250 FPM because the extra speed allows more RPM's and more power.

Regards,
 
2200fpm / 160hp

I did a bit of work trying to work out a climb polar for my -4.

The numbers I came up with were these.

The temp range across the climb was 34 to 38F.
Aircraft - RV4 - 160hp O-320 2-blade MT and dual P-mag
The prop is governed just below 2700 and drifts between about 2640 and 2670 rpm.

Empty weight - 976
Me ----------- 159
Misc ---------- 5
Tot 1140

The fuel varied, but I adjusted all the climb rates back to a gross of 1300lbs allowing for the change in weight for each climb.

I did 7 climbs in total increasing from 75 to 114 mph. Methodology was to descend below 900 ASL and try to enter a full power stable climb by 1500' and hold it until past 3000' I then used the data from approx. 2000 to 3000', as recorded by my AFS3400 for post flight analysis.

At 114 mph I had not reached the peak of the polar but it gave me a climb rate of about 2170fpm. My expectation would be that best climb would be close to 125 mph and probably marginally over 2200fpm.

What I also found out is this:
- At very high pitch angles it is quite hard (at least for me) to fly a really stable climb, for two reasons. a)the lack of a horizon, and b) pitch stability is reducing.

- The air appears never to be quite still.

Looking at HEvans numbers my data would appear to be in line with his calculations. I used 75% efficiency as perhaps being a little more realistic, and also allowing for the fact its not running up to a full 2700rpm.
 
Try to match this rate

I saw a special on the F-15 the other night. It mentioned this specially built F-15 and it's climb record:
The F-15 "Streak Eagle," broke eight time-to-climb world records between Jan. 16 and Feb. 1, 1975. In setting the last of the eight records, it reached an altitude of 98,425 feet just 3 minutes, 27.8 seconds from brake release at takeoff and "coasted" to nearly 103,000 feet before descending.

98,425 ft in 3m27s = 28,446 fpm :)
 
Not even close but we tried....

I saw a special on the F-15 the other night. It mentioned this specially built F-15 and it's climb record:
The F-15 "Streak Eagle," broke eight time-to-climb world records between Jan. 16 and Feb. 1, 1975. In setting the last of the eight records, it reached an altitude of 98,425 feet just 3 minutes, 27.8 seconds from brake release at takeoff and "coasted" to nearly 103,000 feet before descending.

98,425 ft in 3m27s = 28,446 fpm :)

The F-15's were built here in St. Louis on the north side of Lambert. The test pilots frequently used a "Viking Climb" which was vertical to about 5000' and then a roll to resume a more leisurely climb. A very cool maneuver after a minimal take off roll.

I was next behind one of these guys one day taking an MD80 to Kansas City with many empty seats and the usual minimum fuel to get there. I could tell the F/O was thinking the same thing I was, which was how 'bout a mini viking climb. The MD80 produced about 44,000 pounds of thrust and we might have weighed 120,000 lbs. (can't remember the numbers exactly, it was well over 10 years ago, but they are in the ball park) Climb procedure was V2+10 or the max deck angle of the AI and flight director, we just let it go at that deck angle and before switching over to departure the tower guy said, "now that was a mini viking climb, have a good day". There had been no mention of a mini viking climb one the radio. Seems like we were all thinking the same thing. :)

There were lots of fun days working then, back before 9/11 when those darn sneaky rats with box cutters showed up.
 
I am flying an RV-7 weighing at 1053 lbs, Yes I weighed it 3 times!! and just finished doing a climb test for TC certification. My results with an O-360 at 9-1 compression, with a hartzel BF propeller are as follows.

Field Elevation 2500 ft. Temperature 79F. Altimiter 29.83. Gross weight at 1800lbs.

The test was performed for a 3 minute climb starting at 3000 ft altitude once the climb at 110 mph was stabilized. After three minutes the plane passed through 6870 Feet. Which is only 1290 feet/min/avg. It was at gross weight mind you, and the temperature at 6900 feet was still a bomby 70f.. Far Far away from some of the numbers I have been reading.

Now, this same plane solo with lower fuel tanks feels like a rocket, and I have seen the VSI over 2500 many times.
 
The test was performed for a 3 minute climb starting at 3000 ft altitude once the climb at 110 mph was stabilized. After three minutes the plane passed through 6870 Feet. Which is only 1290 feet/min/avg. It was at gross weight mind you, and the temperature at 6900 feet was still a bomby 70f.. Far Far away from some of the numbers I have been reading.
Things are not quite as bad as they seem. The warmer than standard temperatures mean that 3000 ft barometric altitude change is more than 3000 ft of actual altitude change. 70 deg F is 21.1 deg C, or 294.3 deg K. The standard temperature at 6900 ft is 1.3 deg C, or 274.5 deg K. At 6900 ft, the temperature was 294.3/274.5 = 1.07 times standard temperature. So, assuming that the air was similarly warm over the whole altitude block, a rate of climb of 1290 ft/mn of barometric altitude was actually 1.07 * 1290 = 1380 ft/mn of actual altitude change.

And, your engine was down on power because of the warm temperature. You should have at least 5% more excess power if the temperature was standard, so the rate of climb would be at least 1.05 * 1380 = 1450 ft/mn (excess power = power available minus power required to maintain level flight).

Fly safe,
 
Point of Reference: RV-4 /4224 fmp

The current record for class C1.b time to climb to 3000 meters (9843') was set in 1999 by Bruce Bohannon in the Flyin' Tiger and is recorded at 2min 20sec (4224 fpm). It's all about horsepower and Mattituck makes it happen in the Tiger!
 
Catch a ride?

David, I fly out of an airport at 6800' (00V). My Catto does fine BUT all the CS prop guys outclimb me every time.

I fly out of Leadville fine but the CS RVs do better.

My rant suggestion: CS if you can.

Ron,

Do you fly out of Meadow Lake? If so, can I get a ride in your airplane some time? I'm in Longmont, but do get down there on occasion. Do you know what kind of climb rates you're getting. Which airplane are you flying, and with what engine?

Send me an email at [email protected]

David
 
David, I fly a -6A, O-360 that is probably 200HP, Catto three blade prop (standard pitch I think). My RPM at liftoff is 2250-2300. WAG numbers are 1000-1500 FPM on a warm day (density altitude over 8000'), but I would have to give an airspeed to go with that to be of any use.

Next time I fly I will get better numbers. You should have no issues with FP prop out of Longmont (I have been there).

My opinion is 180 HP minimum. CS prop offers significant advantages over the FP prop. If I could magically change to a CS prop at no cost I would do it.
 
Lite RV-4 Numbers

I use the following inputs for my flight planning program. I did a moderate amount of flight testing, and they seem to work out reasonably closely. The first 3 columns after altitude below cruise_alt_inputs_ft are climb numbers, the last 3 are cruise numbers at that altitude. (I don't actually go to 20,000, that's to cap the data). Engine is a 150hp 320, with C/S Prop. Field 460' MSL. Sorry about the spacing, it's the editor.

RV-4 Aircraft_type
928.0 Aircraft_Empty_Wt_lbs_including_oil
61309.0 Basic_Empty_Moment
170.0 Pilot_Wt_lbs
32.0 Fuel_gals
31.0 Usable_fuel_gal
1.0 STTO_gal_fuel
10 cruise_alt_inputs_ft
1000 1.0 0.8 0.1 130.0 9.8 2.0
5000 3.6 2.2 0.5 140.0 8.8 7.0
7000 7.0 3.8 0.8 150.0 8.4 10.0
8000 9.3 4.8 1.0 150.0 8.3 11.0
9000 12.1 6.0 1.3 150.0 8.2 12.0
10000 14.7 7.2 1.5 150.0 8.0 15.0
11000 18.7 9.7 2.1 150.0 7.9 20.0
12000 23.9 10.8 2.4 150.0 7.7 25.0
13000 29.0 12.7 2.5 150.0 7.5 30.0
20000 29.0 12.7 2.5 150.0 7.5 30.0

Alt Dist Time Fuel Cruise Burn Desc_Pt
(Ft) (nmi) (min) (gal) (ktas) (gal/hr) (nmi)
|----climb data-----| |----cruise data------|
Best Short field TO: 80MPH
Best Climb Speed: 90MPH
 
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