Spiffy lokkin 170 at Alexandria

mrpibb · Post by **mrpibb** » Mon May 10, 2004 9:49 pm

Hi guys, Saturday I got my tailwheel endorsment. So today I exercised my endorsment on a little round robin from Aeroflex, Trinca, Hackettstown, Skymanor and Alexandria back to Aeroflex. There's this really spiffy lookin 170 ( Lou's ?) at Alexandria, A real nice silver with red trim, made me real jealouse cause thats the colors I want to do my 48, tried to swap airplanes but to many people around

. Lou, what brand of paint did they use? And congrat's on the new paint, looks great!
Vic

Tue May 11, 2004 12:26 am

Congrats Vic.

That was a mice little trip you took. Trinca and Hackettstown now there's some really nice airports.

mrpibb · Post by **mrpibb** » Tue May 11, 2004 2:54 am

Yea, it's a nice change from the checkout. Got to fly straight and level for more than five minutes instead of staying in the pattern doing three-point,
wheel, crosswind, soft, short , dogleg and Lindbergh landings and takeoffs ( long story)

I got to see what my repitched prop gives me in cruise, I lost about 10 mph at 2450 I would get 115 mph with my 76em53 now I get about 105 mph with It pitched to 50" so I cruise at 110mph at 2500, I was able to get 120 mph just nicking redline. The cool thing is I see about 800+ feet per min. climb, and me being close to 23 stone thats a good thing.
Vic

zero.one.victor · Post by **zero.one.victor** » Tue May 11, 2004 5:47 pm

Your cruise speeds sound a little low,but then again I run a DM76-51. Your EM76-50 should be close. I usually show about 115 at 2450 or so,or 120 or so at about 2550-ish.
You might want to check your airspeed indicator against another airplane's, and/or against a GPS on a calm day. With the GPS, make a stabilized-speed run in each of several directions,jot down your ASI & GPS readings,and average the results. You might also want to borrow a portable tach, & check the accuracy of your tach. Mine reads a bit low, but looking at the gage at an angle from the pilot's seat it's just about right on.
I hope you enjoy your ragwing as much as I have enjoyed mine!

Eric

mrpibb · Post by **mrpibb** » Tue May 11, 2004 8:48 pm

Eric, brought the gps with me on the flight but the winds aloft were a little too strong. Enroute to alexandria at 3000 ft 2500rpm I was indicating 110 mph and the gps showed a ground speed of 102mph and on the return trip the winds picked up with 110 indicated and a ground speed of 132 mph, so untill I get a calmer day and do a four point run Ill know for sure how far of my a/s indicator is. I did check with a hand held tach, my clock is about 25 rpm low. I borrowed a 76em51 prior to the repitch and was 5 mph faster indicated on all rpm settings. I really liked the speed that 53" pitch gave me, but flying out of a 1950' strip speed wasn't going to help me. Kinda wish that some one would design a propeller that you can change the pitch while in flight to optimise performance

Post by **GAHorn** » Wed May 12, 2004 2:30 am

If I bought the rights to the Beech-Roby electrically adjustable propellor and mfr'd it for the 170 and got it certified/stc'd, and offered it for the requisite $9200 ...how many orders would I get? (hypothetically speaking)
I'd settle for a ground-adjustable one. But even that would probably cost more than $5K.

Post by **Bruce Fenstermacher** » Wed May 12, 2004 1:15 pm

George I think you'd get a quite a few orders. Lets see. Buy and install/modify aircraft for 180 or larger engine for more perfomance at a price over $30000 or install a propellor on your already good engine for 1/3rd the cost yet gain a lot (not all I'm sure) of the same performance.

I admit I don't have $10000 laying around waiting for the right new prop but it would be high on my list. I'm very surprised some manufacturer like MT hasn't certified one of their electrically controlled props for the Cessna 150(0200) /172 (0300) and Cherokee 140 (Lycoming0320) market.

N1277D · Post by **N1277D** » Wed May 12, 2004 1:44 pm

A few months ago I contacted MT about an electric prop for the 170. The sales guys said sure we can do it no problem, but the MT engineering people said hold up, not a chance, the best they could do was this. They indicated they could supply a prop (~$10K) but one would have to go a field approval route and one would have to make/provide a hub adapter. They indicated a minimum of two years and $50k or so to get one certified and did not think there was enough demand for MT to go this route.

My guess is that a group would have to come in with several orders and guarantee them a return before they would STC a prop for the 170 series.

funseventy · Post by **funseventy** » Wed May 12, 2004 3:47 pm

Vic,

I would also tell you that your climb performance isn't as good as it could be. If you pull the nose up it will climb slower. Lower the nose and let the RPM's come up and the VSI will show better and with the increased speed the engine will run cooler. I set my climb speed by RPM and I like to climb at 2500 RPM with my 7649 prop. I also run 2550 for cruise and I count on 118. Just like Eric suggested about the airspeed, I would suspect the Tach as well.

Congrats on getting to play!!

Kelly

funseventy · Post by **funseventy** » Wed May 12, 2004 3:50 pm

I would be interested in signing up for the new prop and I could put money up front with some kind of agreement. I think that a prop like that would keep me from selling the 170 in the future. I would never put in a big engine because I'd rather spend the money and step up to a 180 like I used to have. But if I could keep my lovely 6 cylinder and get a little more performance, I'd sure pony up 10K.

Kelly

zero.one.victor · Post by **zero.one.victor** » Wed May 12, 2004 6:43 pm

Vic,I don't know about anybody else,but here is my take on checking indicated airspeed vs GPS groundspeed,FWIW. I would fly the speed runs down low,no more than 3,000' at the very most. I'd be more inclined to go for 1,000', or as close to sea level as practical. I would also fly around & watch how the GPS groundspeed is affected to determine as much as possible the winds-aloft direction at your altitude. I would then finally fly my stabilized speed-runs in four directions-- directly into & away from the wind, and both directions 90 degrees to it. I don't think 4 randomly chosen directions are the right way to do it,but I've talked to people who do it that way.

Eric

mrpibb · Post by **mrpibb** » Thu May 13, 2004 1:47 am

Well as time will tell I'm sure i'll get down to figureing what's what. I think my pitot system is sensitive to certain angles of attack, I checked the contour of the tube but I still have my doubts, I may snag a pitot tester from work to see if my indicator is off, however I planned at the next annual to send my a/s indidcator to be checked and have range marks reapplied. a few weeks ago we came across two cherokee 140's ( Friend of my instructor) flying formation, with permission we joined up for a few minutes ( talk about a motley bunch!!) , they were suprised we were able to keep up with them, I was indicating 125 mph and the said they showed about 130mph I think. As for climb I have been using 70 mph ( on my ASI) , but now that I have my signoff I'm going to try different speeds/angles to see what I get for climb, what are you Ragwing drivers using as climb speeds? as for aproaches It seems that 75mph (on my ASI) has been working.

zero.one.victor · Post by **zero.one.victor** » Fri May 14, 2004 5:20 am

Vic, owner's manual sez use 76 for Vx,and (at sea level) use 89 for Vy (at 10,000' Vy is down to 75). Those numbers seem to work pretty good for me.

Eric

Post by **GAHorn** » Fri May 14, 2004 3:34 pm

Vic, you are correct in that your pitot/airspeed indicating system is sensitive to angle of attack. Performance charts always stipulate which airspeed the chart is based upon. The relationship of IAS/CAS/TAS/TIAS bears this out. For example, CAS takes into consideration instrument error and pitot position error, but IAS does not. TAS is CAS corrected for pressure altitude and temperature. But notice that the Owner's Manual for the 170 is based upon a lesser-utilized TIAS, which is corrected neither for instrument error nor position error, but is corrected for altitude and temperature.
To more accurately fly the airplane than what's already certified, it would take more expensive gauges, pitot/static systems, etc. The few knots differences that exist among our airplanes would not likely be worth the expenditure to upgrade in such a way. (Even if the expense were made at the design stage of development for more accurate instrument indiating systems, it's unlikely the few knots error eliminated would be beneficially utilized by the average pilot.)
But to determine that your system is at least as accurate as it was designed is important and that's why the airspeed and altimeter calibrations are required every two years of aircraft flown IFR, and why ALL aircraft are required to have their transponder/encoders checked every two years.
The bottom line however, is that if your individual system is behaving suspiciously, then you are wise to have a shop verify the accuracy of your indicator and the integrity of your pitot/static system. (And get that altimeter calibrated while you're at it. I'll bet most of the altimeters in 170's have never been calibrated since they were first installed.)

zero.one.victor · Post by **zero.one.victor** » Fri May 14, 2004 4:51 pm

Vic,one easy thing to do is to check the attack angle of the pitot tube when in cruise flight. It should be dead-on to direction of travel-- in other words,level when in level flight. You can tape on a tuft of yarn to see if it streams at the same angle as the pitot, as it should.
I'm gonna start a new thread about props in the "pilot lounge" forum.

Eric

The International Cessna 170 Association

Spiffy lokkin 170 at Alexandria

Spiffy lokkin 170 at Alexandria

MT Propellers