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Old Classic needs upgrade to 912S 100hp

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JonathanMilbank

Joined: 14 Apr 2012
Posts: 391
Location: Aberdeen area

Posted: Sun Jul 28, 2013 1:31 am Post subject: Old Classic needs upgrade to 912S 100hp

After the very successful installation of a tricycle undercarriage, it is clear that there is much greater rolling resistance compared with the monowheel, especially on grass. The best advice is to increase horsepower by replacing my engine with a Rotax 912S.



Neville Eyre has kindly given me answers to some questions and also pointed out that the newer 912S has a larger starter motor, which won't fit into my old-style engine bearer frame. So I'm going to need to acquire a new-ish engine (few 100 hours) with the smaller starter.



How much of a "rod for my own back" will I be making by doing this? How much trouble will I have starting? Is it "wrist-slashingly" frustrating? How long before the starter might need replacing? Will an expensive battery help?



Another serious issue will be engine heat dissipation and Neville has indicated that others have created a "gob" in the cowling below the propeller, directing 1/3 of its air through the oil cooler and 2/3 through the shrouds covering the cylinders.



Please would you help me by sending pictures of such a "gob" intake and also of the additional cooling modifications inside the cowling. All suggestions for effecting this modification and any associated diagrams will be gratefully received.

dg.watts(at)talktalk.net
Guest

Posted: Sun Jul 28, 2013 2:40 am Post subject: Old Classic needs upgrade to 912S 100hp

Jonathan,



After I put 1000 hours on the 912UL in my classic, I replaced it with a 912ULS using the original classic starter plus a Skydrive Soft Start Module and their Carb Heat Kit too.



I now have over 1000 hours on this setup too and as long as the battery is in good condition it starts just fine, summer or winter.



Dave Watts

Classic Monowheel G-BXDY



On 28 Jul 2013, at 10:31, "jonathanmilbank" <jdmilbank(at)yahoo.co.uk> wrote:



 	  Quote: 	
		   

 

 Neville Eyre has kindly given me answers to some questions and also pointed out that the newer 912S has a larger starter motor, which won't fit into my old-style engine bearer frame. So I'm going to need to acquire a new-ish engine (few 100 hours) with the smaller starter.

 

 How much of a "rod for my own back" will I be making by doing this? How much trouble will I have starting? Is it "wrist-slashingly" frustrating? How long before the starter might need replacing?

 

 Another serious issue will be engine heat dissipation and Neville has indicated that others have created a "gob" in the cowling below the propeller, directing 1/3 of its air through the oil cooler and 2/3 through the shrouds covering the cylinders.

 

 Please would you help me by sending pictures of such a "gob" intake and also of the additional cooling modifications inside the cowling. All suggestions for effecting this modification and any associated diagrams will be gratefully received.

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=405476#405476

JonathanMilbank

Joined: 14 Apr 2012
Posts: 391
Location: Aberdeen area

Posted: Mon Jul 29, 2013 1:59 pm Post subject: Re: Old Classic needs upgrade to 912S 100hp

Thanks Dave and I'll take your good advice. When I do the preflight oil tank gurgling on my 80hp engine and then do it on a friend's 100hp 912S, the difference in compression is very noticeable. Hence my concern about whether the older starter motors can cope.



Anyway I've now purchased my 2nd hand replacement engine from Kevin Dilks, sight unseen. Why do I have the confidence to do this? Well, his reputation goes before him for restoring Rotax engines to near-mint condition and another friend has found him to give excellent advice on problems, free of charge and his suggestions work.



Also he was described to me as "a good chap" by no less than Neville Eyre, who did a superb job of fitting my tricycle undercarriage. Recommendations don't come higher than that!



Furthermore he's selling me a 230 hour engine which has been opened, checked carefully and every conceivable part that needed replacing was done with new components. I'm assured that when he says he's done that, you can bet your bottom dollar that he has.



Finally my experience with Rotax 4-strokes tells me that provided they're serviced and operated properly, you can place great faith in them.



I have no qualms and will be collecting the 100 horses on Wednesday.

pete(at)lawless.info
Guest

Posted: Tue Jul 30, 2013 12:11 am Post subject: Old Classic needs upgrade to 912S 100hp

Hi Jonathan



It would be very interesting to get a good comparison of performance for 80

v 100 hp in the same airframe.



If you could assemble some before and after figures for take off roll,

initial climb and a 5 minute timed climb that would be good. Also be

interesting to see how fuel economy is affected. Obviously you would be

trying to get weight, wind and temperature similar.



I was considering a similar swap last year, but could not justify the

expense for the 2 or 3 days a year when our strip seems shorter than usual.



Regards



Pete

--

JonathanMilbank

Joined: 14 Apr 2012
Posts: 391
Location: Aberdeen area

Posted: Wed Jul 31, 2013 2:07 pm Post subject: Re: Old Classic needs upgrade to 912S 100hp

Hi Pete, 



Short of going out to the runway with tape measures and stopwatches,

our comparisons are likely to be rather subjective.



Twice in the last couple of months since fitting the new undercarriage, we have experienced trying to take off on grass with half fuel, little/no headwind and a pilot plus one "fat bastard" passenger. It wasn't fun!



So the real comparison will be made after fitting the new engine and propeller blades and trying to take off again in similar circumstances.



I'll try to remember to let you know after completing the conversion, which won't be for several months.

pete(at)lawless.info
Guest

Posted: Wed Jul 31, 2013 10:37 pm Post subject: Old Classic needs upgrade to 912S 100hp

Thanks Jonathan



So sounds like you have gone trigear?  The conditions (and passenger!) you

describe are exactly when my mono feels under powered.  Mostly from my home

strip I am solo so it is not a problem.



In all cases as soon as the gear/flaps are in there is a really good rate of

climb.



Pete



--

alanb(at)dpy01.co.uk
Guest

Posted: Wed Jul 31, 2013 11:30 pm Post subject: Old Classic needs upgrade to 912S 100hp

Likewise in a 912s powered trigear.



Ok solo but with passenger, I reserve judgement on size, of a rough grass strip I aborted twice.



Not having problems with concrete or firm and well cut grass runway so current conclusion is rough grass strip and warm, calm Wx issues.



Likewise putting flaps up, acceleration on climb out is noticeable good.



Still grinning though.



Alan

On 1 Aug 2013, at 07:35, Pete Lawless <pete(at)lawless.info> wrote:



[quote] 

 

 Thanks Jonathan

 

 So sounds like you have gone trigear?  The conditions (and passenger!) you

 describe are exactly when my mono feels under powered.  Mostly from my home

 strip I am solo so it is not a problem.

 

 In all cases as soon as the gear/flaps are in there is a really good rate of

 climb.

 

 Pete

 

 --

clivesutton

Joined: 23 Jan 2013
Posts: 187
Location: KENILWORTH

Posted: Thu Aug 01, 2013 1:15 am Post subject: Re: Old Classic needs upgrade to 912S 100hp

Gents,

I follow this thread with interest.

I have a tri-gear with 912S and Warpdrive set to 19 degrees pitch.  Have been in and out of a 400m strip with no concerns at MTOW 1370 though climb rate rarely seems to be much better than 700fpm, and usually closer to 550fpm.  I'm not sure I'd ever use a 200m strip (factory performance figures) and 400m is probably the shortest I'd ever be comfortable using.  With GA takeoff safety in mind, I'm toying with developing a device that will alert the pilot if takeoff performance is below par - but before I go and spend the development time and effort, would such an instrument be of interest to anyone/what are readers thoughts on the concept?

Clive.

JonathanMilbank

Joined: 14 Apr 2012
Posts: 391
Location: Aberdeen area

Posted: Thu Aug 01, 2013 1:23 am Post subject: Re: Old Classic needs upgrade to 912S 100hp

[quote="pete(at)lawless.info"]Thanks Jonathan



So sounds like you have gone trigear?  My statement at the beginning "After the very successful installation of a tricycle undercarriage" The conditions (and passenger!) you describe are exactly when my mono feels under powered.  Mostly from my home strip I am solo so it is not a problem.



In all cases as soon as the gear/flaps are in there is a really good rate of

climb.



Pete

kingsnjan(at)westnet.com.
Guest

Posted: Thu Aug 01, 2013 2:16 am Post subject: Old Classic needs upgrade to 912S 100hp

From: "Pete Lawless" <pete(at)lawless.info>



< The conditions (and passenger!) you describe are exactly when my mono 

feels under powered.



Pete,



Could you advise if you have a fixed pitch or constant speed propeller 

please?



Thanks

Kingsley in Oz

pete(at)lawless.info
Guest

Posted: Thu Aug 01, 2013 2:34 am Post subject: Old Classic needs upgrade to 912S 100hp

Hi Kingsley



NSI CAP140 set to give 5,600 rpm static which gives 5,800 rpm at 72kts. No

constant speed unit except my finger.



Normal ground roll off our grass strip which is smooth but humped is sub 200

metres. Hot (by UK standards), humid, no wind or even worse cross wind, and

heavy (MTW 1300 lbs) it goes up to maybe 300 to 350.  I am still 50 feet

over the far hedge but I don't like it.



Pete



--

kingsnjan(at)westnet.com.
Guest

Posted: Thu Aug 01, 2013 1:40 pm Post subject: Old Classic needs upgrade to 912S 100hp

Thanks for that Pete. 



Kingsley



Do not archive



 	  Quote: 	
		   

 

 Hi Kingsley

 

 NSI CAP140 set to ............

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