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climb on RV-4

D

dan carley

Well Known Member
i'm having problems in climb, at 120mph i only get about 1500 fpm and the climb will not hold i have to keep pulling back to hold 1500. in cruise is fine 2450 about 170 moh, top speed 2800 205 mph. i've changed props with no luck. checked mag timing ok, i do have electronic ing, could that be where the problem is? i have no way of checking the electronic ing.

static run up 2090 rpm's. climb out 2200 rpms

i'm really stuck on this one???

dan carley
 
Hi Dan

I need some more information:
engine type and size
D/A of your test
Airspeed true or indicated
aircraft weight at time of test
type of instrument you are recording with.

In my -4 at Carson City with 2 up and full tanks D/A of 6500' wt. 1500 lbs.
I get 1000 fpm at 120 kts. TAS.
 
Prop type and pitch/dia might be helpful too, just to compare with other airplanes. It sounds like you have a cruise prop?
 
I posted my numbers for you in your other thread:

"My rv4 is also 160 hp. I have a Bernie Warnke wooden prop, 70" diameter x 74" pitch. It is a cruise prop so they say. My typical takeoff roll at 500 MSL shows 2100-2150 rpm. I pitch for 100-110 mph IAS and usually see 1400-1600 fpm. If I gain a bit more speed before I pull up then I will see around 2100 fpm but eventually settle back around 1600 fpm at 100-110 mph...aircraft empty weight is around 970lb, I weigh around 170 lb, and I typically take off with full fuel."

Like Dayton says, we need to know the weight of the bird at flight time. The above info is full fuel numbers. At bingo fuel my climb is around 2000 fpm, So weight makes a big difference.
 
climb

this one is a real stumper,information

rv-4 empty weight 960 lbs
lyc o320 d2b 160 hp

catto prop 3 bladed 66x 74 pitch, i did try my friends prop which is a catto 2 bladed(which worked fine on his rv4 diameter 70x72 pitch.
same results with both props.

with the 3 bladed prop static runup 2050 rpms m.p. 28 in.
climb at 120 mph, showing 2200 rpms she will settle in about 1300 fpn but will not hold as i climb.
i am at sea level here.

in cruise 2450 rpm about 160 - 170 mph with 2 in. m.p only 21 in.
full throttle 2800 rpm 209 mph 26 in. m,p

the engine has good compression all 77 or better, engine approx. 130 since over haul, there was a recall on cyl. new ons were3 put on around 60 hr ago. eci cyl.

it has 1 mag and the other one is electronic. while in climb i turn one off then on and then tried the other one. both about the same.

i don't know what else to try,
w&b is slighty aft cg

any clue??

danny
 
Dan, Your numbers don't seem out of the normal range.

As others have been saying, to get a good benchmark you need to specify all the conditions.

I'd suggest something on the lines of: Note take off weight; stabilise a climb at constant airspeed, say 100-120mph, and measure your time from 2000' to 3000' while holding attitude and airspeed as constant as possible; note the OAT or get it from the area forecast and correct the altitude for D.A.. Repeat at a few different altitudes and climb speeds. Taking a video of the panel saves a lot of note taking in flight.

Vans' put a graph of similar information for an RV-6 in their info pack at one time. I don't have a copy handy, but it would make a good basis for comparison if you can get hold of it.
 
I have an RV-8 with O-360 and a 3 blade CATTO 66x75 gen 2 prop.
I get a static 2088 RPM and climb out about 2200 RPM.
I also have less than spectacular climb, probably because the engine can not make full power at such a low RPM.
My T-18 has a Ted Hendrickson 68x68 2 blade being turned by a converted O-290G. It has a static 2360 RPM. It tops out at 2660 RPM @ 4000 MSL.
I would prefer my RV-8 CATTO combination be similar to my T-18 for take off & climb, but I can't fault the X-country performance, it's about perfect.
I'm not ready to call Craig CATTO for a prop modification, I have about 70 hours on the RV-8, and still need to work on drag reduction around the canopy, cowl and gear.
You seem to be getting very good top speed, so your power and prop pitch seem fine, I wonder if (for both of us) the blade area could be reduced a little so the engine can turn faster for static and take-off RPM, yet hopefully retain the top speed & RPM?
 
climb

the wx has been pretty much the same for tests, around 65-70 degrees, i have done similar tests at 2000 ft going from full throttle bring it back to 120 mph first it will read 2000fpm but as i hold the climb will go back down to about 1300 fpm at 120 mph.flying weight just me, tried with full tanks- to 1/4 tanks of fuel. i'm using a ems and did check it with a hand held tac. egt and cht are reading normal.

air speed gauge was checked against ipad with garmin pilot also the vsi and altimator. all were very close.


danny
 
with about 12 gallons of fuel and just myself (235lbs) i peg the vsi at 4000fpm at 80 kts indicated.I have to push over before I violate the class C airspace.
 
Michael Henning said:
with about 12 gallons of fuel and just myself (235lbs) i peg the vsi at 4000fpm at 80 kts indicated.I have to push over before I violate the class C airspace.
Click to expand...

Neat, but not exactly a fair comparison with at least 20 more hp and a constant speed prop. You're able to dedicate probably 50 hp more to the climb than the OP.
 
Dan have you gone through the exercise of determining your best climb speed? There are probably lots of threads and articles in various places on how to do it. It will be different for every airframe/engine/prop combination. Don't assume that just because Van publishes a number that you will gettin he same thing. An airplane with a cruise prop will have a higher best climb speed than one with a climb prop. I think you need to do this to know where you stand relative to other similar airplanes.
 
If you are getting over 200 mph in level flight then I think your engine is putting out full power because that's pretty respectable. Could it be that your EI timing curve is not optimal for lower rpm? Are there different curves you can try?

It sort of seems that you just have a setup that is optimal for cruise, not climb. Or your VSI is out of calibration? Try time to climb with a watch rather than the VSI....or have you done that?
 
climb

i've timed it with a watch very close. it could be the electronic ing. there instructions are very hard to follow.

danny
 
climb

i did change props we took one off my friends rv4 same as mine, with this prop he was getting close to 2000 fpm and can hold it up to almost 7000 feet, when we put it on mine still only 1500 fpm and would not hold the climb, could it be something in the ram air

danny
 
climb

both aircraft's are about the same. same engine same weight he does have pressure recovery wheel pants. other than that about the same

danny
 
climb

i would like to get a better rate of climb and have it hold up to altitude.

right now i can only get around 1400 fpm at 120 mph and i can't hold that for long maybe till 3000 ft and then it will drop off.


i have a lse plasma 3 ignition system on my left side. does any one know this system? i've heard you can time it for maximum cruise, this might be the problem. i don't think it's working property? the mp line that goes to the box had a little oil in it. i cleaned it out and installed it back and the gauge is reading 28" but my regular mp gauge is reading 30". and in flight the lse mp gauge reads a lot lower then my regular gauge. his might be a problem in advancing the electronic ing.

any one had any experience with this unit? there instructions are not very good

danny
 
Frustrating post!

Dan

With respect if you want people to help you you need to supply information they ask for. Density altitude, weight of aircraft and pilot, and actual take off weight of the aircraft. Where you say you swapped props with a friend, what static RPM did he turn compared to your aeroplane, what was the takeoff weight of his compared to yours.

I have a fp Sensenich on my 160 hour 4 and fly from 150 ft above sea level. Empty weight is 1000lbs with me on board 1170 and full fuel pushes that up to 1350 lbs. I get 2200 rpm static and climb out at 120 and get 1500 rpm like you. Again like you at 2400 Rpm I get 170mph.

So, either both our aircraft are under performing in climb or we are getting what is normal performance for a 4, assuming your takeoff weight and Da are the same as mine. If I am at gross 1550 lbs in the UK the climb will drop to 1300 fpm. Weight has a big effect!!
 
climb

steve
in previous post i did state a lot of the facts,i did not know the da that day, his aircraft is 20 lbs heaver and he's about 20 lbs heaver than me. static on both props 2040 both props had same numbers. climbs at 2200 rpms. i am at sea level. we are kinda thinking the lse plasma 3 is not advancing properly. checked and cleaned and timed the other mag,

danny
 
climb

this is my second rv, my first one would hold at least 1800 fpm to 7000 ft.
it is the same as this one, the new one really drops of the rate of climb fast, buy the time i'm at 3000 feet it's down to 900 fpm, i'm thinking the electronic is either is bad or the timing is off. my first one just had 2 mags.

danny
 
FF?

Maybe I missed it but what is your fuel flow during your full power speed runs and during your best climb? Maybe overly lean or rich.
 
Advance

Dan

Have you got a display for how much advance the plasma is putting out.

Did both engines turn the same rpm in the climb at the same airspeed?

I inTend to go do some circuits if the wind is friendly today I will try to note all my numbers for you.
 
kd7erc.jpg
[/IMG]
This was today in cruise config.
climb out to 7500 was 1200-1300fpm
 
Props

What I am trying To establish is what Rpm your aircraft and your friends did with the same prop. If the fIgures are the same at the same airspeed the engines are putting out the same power.
 
climb

both props were on my rv4 same plane just switched props.

what i'm trying to find out, could the electronic ing. be the problem. we took the regular mag off inspected and cleaned it and timed it so that mag is not the problem, we suspect the electronic on is not advancing. would that hurt the climb?

danny
 
dan carley said:
both props were on my rv4 same plane just switched props.

what i'm trying to find out, could the electronic ing. be the problem. we took the regular mag off inspected and cleaned it and timed it so that mag is not the problem, we suspect the electronic on is not advancing. would that hurt the climb?

danny
Click to expand...
Correct me if I?m wrong guys but the EI should not be advancing during high MP/power operations, takeoff, climb out etc. at takeoff power your mag and your EI will both be firing at 25 degrees BTDC. If that?s correct then not advancing won?t be your problem. The advance in your EI is for reduced power cruse economy.
 
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