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John Heykoop

Joined: 10 Jan 2006
Posts: 15

Posted: Sat Sep 29, 2007 9:30 am Post subject: Woodcomp scimitar blades (was Emailing: IMG_0410, IMG_04...

Carl

  

 Andy Draper said the following in a letter he wrote me on 15th  August.

  

 " The Woodcomp scimitar blades are acceptable, however there is an  issue with the diameter. The maximum diameter propeller accepted on the  Europa XS monowheel is 64" (1625mm). If you wished to fit a larger diameter  propeller, you will need to show compliance with CS-VLA925. Amongst other things  to check, the ground clearance from the propeller tip with the aircraft fully  loaded, in a level attitude and with a flat tyre must be at least 230mm."

  

 Andy therefore seems to think you do have to have a minimum of   230mm clearance with a deflated tyre. However, I agree with your interpretation  of the rules, and I think he could be persuaded that with a deflated tyre  the rules only require "positive clearance".   

  

 Regards

  

 John

  

  

 In a message dated 28/09/2007 16:26:01 GMT Standard Time,  carl.pattinson(at)btinternet.com writes:

  	  Quote: 	
		  John,



Having tracked down the VLA specs I had a look at what it    had to say about prop clearances. Unless I am very much mistaken I dont    beleive the tyre should be deflated to achieve the 230mm    clearance.



Here is the actual wording



"(a) Ground clearance.    There must be a clearance of at least 180 mm (for each aeroplane with nose    wheel landing gear) or 230 mm (for each aeroplane with tail wheel landing    gear) between each propeller and the ground with the landing gear statically    deflected and in the level, normal take-off, or taxying attitude, whichever is    most critical. In addition, for each aeroplane with conventional landing gear    struts using fluid or mechanical means for absorbing landing shocks, there    must be positive clearance between the propeller and the ground in the level    take-off attitude with the critical tyre completely deflated and the    corresponding landing gear strut bottomed."



If my interpretation is    right there have to be two checks made. You first load the aircraft up to its    maximum weight and the clearance has to be in excess of 230mm, then you    deflate the tyre and there should then be what they describe as "positive    clearance" .



Having said this my understanding is that most Classic    Europas would fail the VLA test even with the 1575 blade fitted (ie: the Warp    Drive). However the ruling is not retrospective so should not affect existing    approved installatons.

Apparently the XS monos are not similarly    affected because the XS engine mount raises the propeller by about 1.5"    (compared to the mono. Consequently the 1625mm prop can be    approved.



None of which is any help to me - it seems the Woodcomp is a    non starter.



	


 

  

     [quote][b]

pete(at)lawless.info
Guest

Posted: Sat Sep 29, 2007 10:34 am Post subject: Woodcomp scimitar blades (was Emailing: IMG_0410, IMG_04...

Carl/John  

   

The way I read that is that the sentence requiring you to deflate the tyre only applies to “for each aeroplane with conventional landing gear struts using fluid or mechanical means for absorbing landing shocks”.  Unless there are more words elsewhere in the regulation that are not in this email  

   

Pete  

   

   

--

Carl Pattinson

Joined: 26 Sep 2007
Posts: 11

Posted: Sat Sep 29, 2007 10:46 am Post subject: Re: Woodcomp scimitar blades (was Emailing: IMG_0410, IMG_04

Thanks John,



The problem is that we have a Classic Europa which is 1.5" closer to the ground and it seems that all current propellers (including the approved 1575 mm dia ones) would not pass the VLA requirements.



I am going to make some measurements tomorrow to check this is the case.



The only way it seems that we could fit the Wood-comp prop would be to upgrade the front end of the AC to the XS specs - it simply wouldn't be cost effective and probably cost more than the prop.



The only reason we are seriously considering fitting a VP prop is because of Mod 74 - there seems to be no point in doing this without incorporating Mod 52 (weight increase mod). 



The only other serious option is the air master setup which is the one favored by the PFA. The Arplast from what I hear is not particularly reliable due to their using an underpowered motor.



I was hoping that with William Mills using a Scimitar blade prop on his Classic it would be relatively straight forward but Woodcomp themselves say this particular prop is 1650mm and that they never made anything smaller. 



Carl Pattinson

G-LABS

Carl Pattinson

Joined: 26 Sep 2007
Posts: 11

Posted: Sat Sep 29, 2007 11:01 am Post subject: Re: Woodcomp scimitar blades (was Emailing: IMG_0410, IMG_04

Pete,



The wording quoted in my email is precisely as per the VLA manual. There is more on the subject further in the chapter but not relevant to the clearance issue.



None the less I am inclined to agree that this would be the official interpretation though I would be tempted to argue the case with the PFA. IMHO the actual wording is perfectly clear and logical when you think about it (ie: it allows for the possibility of a puncture). There seems to be no merit in insisting that there is at least 230mm with the tyre deflated - what would that achieve?



When I have made some measurements (which I will do tomorrow) I will know if there is any chance of putting forward a valid argument.



One further thought is that when the aircraft about to off (ie: level) the undercarriage is supporting very little load as this is taken up by the wings. In the landing configuration the prop is nowhere near the ground (ie: stick well back). I wouldn't expect the PFA to buy that argument though.

Mark Burton

Joined: 10 Jan 2006
Posts: 74

Posted: Sat Sep 29, 2007 12:12 pm Post subject: Re: Woodcomp scimitar blades (was Emailing: IMG_0410, IMG_04

Carl, 



Responding to two of your points:



I should think that the prop to ground clearance would be at a minimum on a heavy arrival when the main gear tyre and suspension is compressed and, possibly, the tail is still in the air.



The paperwork that came with my scimitar bladed SR3000 states it is 1625mm in diameter (not 1650).  Perhaps the paperwork is wrong. If it is, do I have to saw 1/2" of each tip?



Mark

Carl Pattinson

Joined: 26 Sep 2007
Posts: 11

Posted: Sat Sep 29, 2007 1:21 pm Post subject: Re: Woodcomp scimitar blades (was Emailing: IMG_0410, IMG_04

Mark,



On a mono wheel Europa if you land in a "level" attitude you are heading for trouble anyway. The ideal attitude is tail and main wheel simultaneously though tail first is acceptable. 



I emailed Andy on Friday and here is part of his reply



"The largest diameter prop that is accepted for use on a mono-wheel Europa with the Classic engine installation is 62" (1575mm).  The XS engine installation places the engine 1.5" higher and therefore a 65" (1650mm) diameter is accepted, although generally the 64" (1625mm) diameter is used.

 

On a recent check that I did on ground clearance, if the VLA requirements were adhered to, then the Classic mono would be limited to about a 56" diameter! "



I also spoke to Conrad Beale and he tells me that the standard Europa Wood-comp is 1625mm and the Scimitar Wood-Comp is 1650mm. Wood-comp say they only use one mould for each prop and that the sizes have always been the same. 



It doesn't really matter if your Scimitar prop is 1625 or 1650 because (presumably) there is more than adequate clearance with the tri-gear setup.



It would be worth knowing what the measured diameter of your prop is - hopefully its the same as the paperwork.



What concerns me is that Woodcomp says the Scimitar prop is 1650 mm (65") but your paperwork (and Williams) says it is 1600 mm (63").



If you don't believe me heres the link to Woodcomps specs.



http://www.ekmpowershop2.com/ekmps/shops/conairsports/sr3000-2-blade-wood--composite-prop-scimitar-blades-316-p.asp

Carl Pattinson

Joined: 26 Sep 2007
Posts: 11

Posted: Sat Sep 29, 2007 1:32 pm Post subject: Re: Woodcomp scimitar blades (was Emailing: IMG_0410, IMG_04

This is probably a better link to the Woodcomp specs.



http://www.conairsports.co.uk/Woodcomp%20Pricelist.pdf

Mark Burton

Joined: 10 Jan 2006
Posts: 74

Posted: Sat Sep 29, 2007 1:59 pm Post subject: Re: Woodcomp scimitar blades (was Emailing: IMG_0410, IMG_04

Carl,



The people with tape measures don't care about it being better to land tail down. If it's possible to plant the thing heavily on the mainwheel in a level attitude then that's what it has to be able to cope with (from a prop clearance point of view).



Personally, I don't believe William's prop was 63" in diameter. From memory,  he (verbally) told me: "I asked for a 63 inch prop, and that's what I believe I got". I don't know if he ever measured the diameter.



Mark

kheindl(at)msn.com
Guest

Posted: Sat Sep 29, 2007 2:17 pm Post subject: Woodcomp scimitar blades (was Emailing: IMG_0410, IMG_04...

Carl,



The Woodcomp specs are not always correct. On paper my prop is 1750, but the 

actual diameter is 1720. Also, the specified weight is less than the actual.



Karl





 	  Quote: 	
		  From: "Carl Pattinson" <carl.pattinson(at)btinternet.com>

Reply-To: europa-list(at)matronics.com

To: europa-list(at)matronics.com

Subject: Re: Woodcomp scimitar blades (was Emailing: IMG_0410, 

IMG_04...

Date: Sat, 29 Sep 2007 14:21:38 -0700




<carl.pattinson(at)btinternet.com>



Mark,



On a mono wheel Europa if you land in a "level" attitude you are heading 

for trouble anyway. The ideal attitude is tail and main wheel 

simultaneously though tail first is acceptable.



I emailed Andy on Friday and here is part of his reply



"The largest diameter prop that is accepted for use on a mono-wheel Europa 

with the Classic engine installation is 62" (1575mm).  The XS engine 

installation places the engine 1.5" higher and therefore a 65" (1650mm) 

diameter is accepted, although generally the 64" (1625mm) diameter is used.



On a recent check that I did on ground clearance, if the VLA requirements 

were adhered to, then the Classic mono would be limited to about a 56" 

diameter! "



I also spoke to Conrad Beale and he tells me that the standard Europa 

Wood-comp is 1625mm and the Scimitar Wood-Comp is 1650mm. Wood-comp say 

they only use one mould for each prop and that the sizes have always been 

the same.



It doesn't really matter if your Scimitar prop is 1625 or 1650 because 

(presumably) there is more than adequate clearance with the tri-gear setup.



It would be worth knowing what the measured diameter of your prop is - 

hopefully its the same as the paperwork.



What concerns me is that Woodcomp says the Scimitar prop is 1650 mm (65") 

but your paperwork (and Williams) says it is 1600 mm (63").



If you don't believe me heres the link to Woodcomps specs.



http://www.ekmpowershop2.com/ekmps/shops/conairsports/sr3000-2-blade-wood--composite-prop-scimitar-blades-316-p.asp





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=137162#137162






	


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ami(at)mcfadyean.freeserv
Guest

Posted: Sun Sep 30, 2007 1:21 am Post subject: Woodcomp scimitar blades (was Emailing: IMG_0410, IMG_04...

I'd be interested to hear views on the suitability of the area of the SR3000 

blades. This appears much larger than the competition (excepting the 

Rospeller)and I wonder whether it's too much for at least the 80 hp 912.

Probably perfect for 914 at high altitude!



Duncan McF.

---

Mark Burton

Joined: 10 Jan 2006
Posts: 74

Posted: Sun Sep 30, 2007 8:03 am Post subject: Re: Woodcomp scimitar blades (was Emailing: IMG_0410, IMG_04

Duncan,



I think you may be right because with my 912, the coarse limit has to be set relatively fine so that I can achieve the +ve rate of climb in fully coarse that the PFA demand but that then means that it runs out of pitch if I try to cruise using less than about 4800 RPM.



On the plus side, the prop does seem to pull very well at low speed - does that make sense?



Mark

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