Matronics Email Lists :: View topic - A question of horsepower...

Matronics Email Lists
Web Forum Interface to the Matronics Email Lists

Get Email Distribution Too! FAQ Search Memberlist Usergroups Register

Profile Log in to check your private messages Log in

A question of horsepower...

Matronics Email Lists Forum Index -> Zenith701801-List

View previous topic :: View next topic

80 horsepower or 100 hp?

80 hp

[ 0 ]

100 hp

100%

[ 3 ]

Total Votes : 3

Author Message

pdknight

Joined: 14 Aug 2008
Posts: 8

Posted: Thu Sep 04, 2008 7:33 pm Post subject: A question of horsepower...

I was just looking over the numbers on the Zenith webpage for performance with an 80hp powerplant versus a 100hp powerplant.  Using their Rotax example, the 80 hp engine will give a "dual" takeoff roll of 115 ft.  The 100 hp engine gives a takeoff of 90 ft.  Therefore, 2000 extra bucks gets you a 25 ft shorter takeoff roll, and giving an extra 100 fpm climb.

Great Plains redrives 1915cc engine advertises 85 hp on takeoff and 65 in cruise, while the 2180 gives 105 on takeoff and 70 in cruise.  The price difference is much closer than with the rotax engines, being 600 more for the 105 hp model.   It gives 18 more hp on takeoff, but only 5 more in cruise.  There is a question coming up somewhere in this rant.

From what I have heard, few people can match the factory performance estimates, even with the exact same engines.  Real world wise, what are you all seeing from your aircraft, such as with an 80hp and 100hp?  Obviously, 20 extra hp has its benefits, but 25 ft worth of benefit?  Is the extra expenditure worth that few extra hp?

I ask only because I am trying to get my powerplant decision narrowed down soon, and my experience in general aviation and prop aircraft is somewhat limited.   Thanks for the input.

graeme(at)coletoolcentre.
Guest

Posted: Thu Sep 04, 2008 8:46 pm Post subject: A question of horsepower...

If you have the extra $2000 you will not go wrong with the 100hp

115ft dual with 80 HP would have to be at sea level on a cold day.

Ask yourself

do you fly in cold weather at sea level all the time

do you fly by your self

how heavy are you and your co passenger

repeating

If you have the extra $2000 you will not go wrong with the 100hp



Graemecns



---

jetboy

Joined: 22 Jul 2006
Posts: 233

Posted: Thu Sep 04, 2008 8:53 pm Post subject: Re: A question of horsepower...

a better way to ask this question is : 



have you changed or wanted to change engines, with / from what type and why?



What you summised about the Rotax and corresponding VW choices is quite reasonable. Can't remember if it is Valley or Great Plains that have the water cooled / dual ignition option, but they state clearly its to provide an alternative to the Rotax. Of concern and you can read it in detail on one of those websites is the taper coupling used on some crankshafts, I tend to prefer the flywheel end drive for the more reliable connection.

Another issue is cooling, a 701 with 2180 VW and redrive burnt it up in under 40 hrs although that failure was put down as lean mixture and he's flying again. Another 701 here had a Corvair but replaced it with a Jabiru 2200 as the Corvair proved too heavy and thirsty for 2 up and cross country.



I have the Jabiru 2200, with a custom matched wood prop, and its a good balance for me. its not worth quoting figures, people pick on the smallest of discrepancies, basically what you get is the product of thrust minus penalty of weight. Using a redrive allows a large 2 blade prop for max efficiency, but poor air cooling (for the 701) and higher weight. Using a 2 stroke cuts the weight and reliability, in my direct experience. The direct drive Jabiru suffers due to practical limitation of 64" prop dia. for the rpm it turns, loosing 5% thrust efficiency, thats why a 582 powered 701 can climb just about the same.



While the claimed TO distances might appear the only difference, it matters not because the plane needs more distance to land in. Climb rate for me is the important factor, and of known available packages the  Rotax 914 would be my first choice, going down in price I'd consider the Jabiru 3300 then perhaps the 80 hp 912, Jabiru 2200 or one of the VW variants (but pick a good one, not sure they are all equal)



The reason I passed on the most popular 912s is it has proved harsh operating in the 701, more stressed than the 80hp, besides if I needed the extra power I'd rather supercharge or turbo the cheaper 80hp.

I could not consider this option on a Jabiru or VW, they dont stay together for long enough on their own, This reliability / longevity factor is probably more a deciding factor.

 As I have only 250 hrs on the Jabiru I cannot be certain of its future, it has not faltered in any way to date, I am well aware of many others (Rotax, VW and Jabiru) that have experienced a high 'no go' / stoppage rate.



Apologies if this answer got a bit long, just my thoughts which are constantly updating



Ralph

_________________
Ralph - CH701 / 2200a

John Bolding

Joined: 23 May 2006
Posts: 281

Posted: Fri Sep 05, 2008 3:32 am Post subject: A question of horsepower...

Ralph,  Last time I "talked" with John Lowther he was building up another 

Vair to reinstall in his 701, are you aware if he completed that 

installation or not ?



 Thanks,    John



 	  Quote: 	
		   



 What youAnother 701 here had a Corvair but replaced it with a Jabiru 2200 

 as the Corvair proved too heavy and thirsty for 2 up and cross country.



 Ralph

ricklach

Joined: 20 Jun 2006
Posts: 127
Location: Kernville, Calif.

Posted: Fri Sep 05, 2008 7:11 am Post subject: Re: A question of horsepower...

I fly the 100HP 912S and itâ€™s wonderful. I live at 6500FT with an 800FT strip and 70FT pine trees all around. More than once I believe the extra power has not only saved me but givens me that very comfortable margin of safety. If you fly into and out of long strips never go around mountains or fly at gross weight the lower horsepower is great. But for my kind of flying the extra power is wonderful. You can never have enough of a safety margin.



I also like Chris Desmondâ€™s video â€œCanyon Flyingâ€ where he dose a power on stall and has â€œ0â€ air speed and is still showing a vertical clime.



Rick

ronlee

Joined: 25 Dec 2006
Posts: 141

Posted: Fri Sep 05, 2008 10:02 am Post subject: Re: A question of horsepower...

I live and fly at altitude of 3500 feet with temps. of 100+ degrees at times. Our normal flying height is around five to six thousand feet. I have a 912uls in my 701 and can honestly say I would not be happy with any less power or torque at the prop. I have never had an overheating coolant or oil problem. I can sincerely say that I can't think of one Jabiru installation in any plane that has not been plagued by high head temps. especially on take off. Other then that they seem to be fine. About the only thing that I don't like about the 912uls is having to use high octane auto fuel or 100LL. It can be hard to find a station that sell lots of premium and that is necessary as Rotax wants fresh gas used. I usually buy my gas in an area where there are alot of high end cars as they require premium fuel and I feel I have a better chance of getting fresh fuel at at those stations. Could I get by with the 80HP? yes but it would not be as much fun. Can one ever have too much power?

Ron Lee

Tucson, AZ

_________________
Ron Lee
Tucson, Arizona

n801bh(at)netzero.com
Guest

Posted: Fri Sep 05, 2008 10:22 am Post subject: A question of horsepower...

Yup... My 801 has TOO much power. It has only tried to kill me once because of it and I won't try that trick again, The details are................. I tried a full flaps, stick all the way back, brakes locked take off at minimum weight. Plane rolled about 80 feet, rotated and climbed in a flat attitude, airspeed indicator was even showing anything so it was less then 20 mph. Got to about 50 feet agl and the thing decided to roll inverted. The flaperons were not effective because of the slow air speed passing over them but the big prop  and all the extra HPhad a tremendous torque roll happening. I reduced power, stepped on the rudder and pushed the nose over all in about 1/2 second. Another second or two and I would have crashed.  This puts a new meaning to getting on the "front" side of the power curve....  Never again will I try to get it in the air till I see at at least 30 mph on the ASI. 

  

do not archive

Ben Haas

N801BH

www.haaspowerair.com



-- "ronlee" <rlee468(at)comcast.net> wrote:

--> Zenith701801-List message posted by: "ronlee" <rlee468(at)comcast.net>



I live and fly at altitude of 3500 feet with temps. of 100+ degrees at times. Our normal flying height is around five to six thousand feet. I have a 912uls in my 701 and can honestly say I would not be happy with any less power or torque at the prop. I have never had an overheating coolant or oil problem. I can sincerely say that I can't think of one Jabiru installation in any plane that has not been plagued by high head temps. especially on take off. Other then that they seem to be fine. About the only thing that I don't like about the 912uls is having to use high octane auto fuel or 100LL. It can be hard to find a station that sell lots of premium and that is necessary as Rotax wants fresh gas used. I usually buy my gas in an area where there are alot of high end cars as they require premium fuel and I feel I have a better chance of getting fresh fuel at at those stations. Could I get by with the 80HP? yes but it would not be as much fun. Can one ever have too much power?

Ron Lee

Tucson, AZ



--------

Ron Lee

Tucson, Arizona





Read this topic online here:



http://forums.matronics.com/viewtopi================================================   --> http://www.matronics.com/Navigator?Zenith701801-List========================bsp;          - MATRON================================================;       - List Contribution Web Site sp;                       &nb===================================================

  



____________________________________________________________ 

[url=_blank]Click here for free information on nursing degrees, up to $150/hour[/url]

  [quote][b]

jetboy

Joined: 22 Jul 2006
Posts: 233

Posted: Fri Sep 05, 2008 1:22 pm Post subject: Re: A question of horsepower...

answer to John Bolding:

I contacted John Lowther when I got my custom prop made for the 2200, same type that he used, late last yr. Athough the Corvair made a very impressive photo during ground tests, (might appear on the ZAC site?) he soon found its only attribute was climbing at over 1000 fpm. He sold the engine although I thought he was getting another for someone else or a different plane, not a 701 installation. He also said the 701 started life with an HKS (never flew) then Corvair now 2200a



Ralph

_________________
Ralph - CH701 / 2200a

pdknight

Joined: 14 Aug 2008
Posts: 8

Posted: Fri Sep 05, 2008 1:37 pm Post subject: Re: A question of horsepower...

Thanks for all the constructive responses.  One of my biggest issues is that of the financial variety when it comes to engine choices.  I have been giving a lot of attention to the VW redrives.  The issue of longevity and reliability is a concern, for sure.  Great Plains is not the best when it comes to responding to emails concerning their products, which, I have to admit, had been a bit of a turn off from the company.  Culver is making a redrive, but it has only recently been released, and I don't think a lot of them are flying.  GP has been around for quite some time and has a lot of engines out.  Does this speak for the "reliability" of the engines, or are the customers willing to accept the degraded longevity and reliability, or expect it from a redrive?

John Bolding

Joined: 23 May 2006
Posts: 281

Posted: Fri Sep 05, 2008 2:46 pm Post subject: A question of horsepower...

Don't know what you mean by "recently" but the Valley Engineering (Culver) 

has been sold for a number of years and has a good reputation,  they ALSO 

make the redrive that Great Plains sells , or it was the last time I looked.

Cooling, at continued high power settings, will always be a problem on the 

VW however.

John

---

ggower_99(at)yahoo.com
Guest

Posted: Fri Sep 05, 2008 9:33 pm Post subject: A question of horsepower...

Ben,  Just imagine that myself,  makes me cold sweat!   Good you made it...   

  

 Like one time in my old V8 Pickup when a teen,  once I floored the gas in a corner downtown.  Missed 3 cars, a light post, one pedestian and a news stand for inches, before I could regain control and stop... 

  

 Saludos

 Gary Gower

 Do not archive.



--- On Fri, 9/5/08, n801bh(at)netzero.com <n801bh(at)netzero.com> wrote:



  	  Quote: 	
		  From: n801bh(at)netzero.com <n801bh(at)netzero.com>

Subject: Re: Re: A question of horsepower...

To: zenith701801-list(at)matronics.com

Date: Friday, September 5, 2008, 2:20 PM



  Yup... My 801 has TOO much power. It has only tried to kill me once because of it and I won't try that trick again, The details are.................. I tried a full flaps, stick all the way back, brakes locked take off at minimum weight. Plane rolled about 80 feet, rotated and climbed in a flat attitude, airspeed indicator was even showing anything so it was less then 20 mph. Got to about 50 feet agl and the thing decided to roll inverted. The flaperons were not effective because of the slow air speed passing over them but the big prop  and all the extra HPhad a tremendous torque roll happening. I reduced power, stepped on the rudder and pushed the nose over all in about 1/2 second. Another second or two and I would have crashed.  This puts a new meaning to getting on the "front" side of the power curve....  Never again will I try to get it in the air till I see at at least 30 mph on the ASI.

  

 do not archive

Ben Haas

N801BH

www.haaspowerair.com



-- "ronlee" <rlee468(at)comcast.net> wrote:

--> Zenith701801-List message posted by: "ronlee" <rlee468(at)comcast.net>



I live and fly at altitude of 3500 feet with temps. of 100+ degrees at times. Our normal flying height is around five to six thousand feet. I have a 912uls in my 701 and can honestly say I would not be happy with any less power or torque at the prop. I have never had an overheating coolant or oil problem. I can sincerely say that I can't think of one Jabiru installation in any plane that has not been plagued by high head temps. especially on take off. Other then that they seem to be fine. About the only thing that I don't like about the 912uls is having to use high octane auto fuel or 100LL. It can be hard to find a station that sell lots of premium and that is necessary as Rotax wants fresh gas used. I usually buy my gas in an area where  there are alot of high end cars as they require premium fuel and I feel I have a better chance of getting fresh fuel at at those stations. Could I get by with the 80HP? yes but it would not be as much fun. Can one ever have too much power?

Ron Lee

Tucson, AZ



--------

Ron Lee

Tucson, Arizona





Read this topic online here:



http://forums.matronics.com/viewtopi================================================   --> http://www.matronics.com/Navigator?Zenith701801-List========================bsp;          - MATRON================================================;       - List Contribution Web Site sp;                       &nb===================================================



____________________________________________________________ 

Click here for free information on nursing degrees, up to $150/hour

 	  Quote: 	
		  

	


	


         [quote][b]

n85ae

Joined: 14 Mar 2007
Posts: 403

Posted: Mon Sep 08, 2008 12:12 pm Post subject: Re: A question of horsepower...

I never saw any responses to Ben's post, but I for one paid attention.

My Kitfox with it's 125 hp Continental is as tame as they get for example

in a power off stall, but power on with it's high lift wing and flaperon's

it will fly at insane nose high attitudes before violently snapping into

a wing dropping stall. 



Ben's post is thought provoking because high power engines with high

lift wings make you feel pretty invincible when you fly them, but they

can get you into flight regime's that produce pretty unexpected results

when things don't do what you expect.



Thanks for the post Ben.



Jeff  

 	  Quote: 	
		  Yup... My 801 has TOO much power. It has only tried to kill me once because of it and I won't try that trick again, The details are................. I tried a full flaps, stick all the way back, brakes locked take off at minimum weight. Plane rolled about 80 feet, rotated and climbed in a flat attitude, airspeed indicator was even showing anything so it was less then 20 mph. Got to about 50 feet agl and the thing decided to roll inverted. The flaperons were not effective because of the slow air speed passing over them but the big prop  and all the extra HPhad a tremendous torque roll happening. I reduced power, stepped on the rudder and pushed the nose over all in about 1/2 second. Another second or two and I would have crashed.  This puts a new meaning to getting on the "front" side of the power curve....  Never again will I try to get it in the air till I see at at least 30 mph on the ASI.

vgstol(at)bigpond.net.au
Guest

Posted: Mon Sep 08, 2008 1:34 pm Post subject: A question of horsepower...

Really good cautions  from both Jeff and Ben.

  

 "....high power engines with high lift wings make you feel pretty  invincible when you fly them...."

                          and

 "...This puts a new meaning to getting on the "front" side of the power  curve...."

  

 I know of a couple of 701's  that have been considerably 'crunched' on take-off by this 'torque roll'  reaction .  

 An analysis of one such  incident in a Savannah is at http://www.stolspeed.com/id/31   

  

 Yes, we feel invincible in  these aircraft, but some caution is needed with such high power at  very low airspeed.  When it goes wrong it happens real quick, with  little chance to recover....

  

 JG

  

 [quote]   ---

Display posts from previous:

	Matronics Email Lists Forum Index -> Zenith701801-List	All times are GMT - 8 Hours
Page 1 of 1

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum