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Grumman strength
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david(at)carneyaviation.c
Guest

Posted: Fri Apr 07, 2006 1:55 pm Post subject: Grumman strength

# Certified aircraft are required (FAR Part 23) to be dive tested

# (design dive speed) to 10% above what the manufacture sets as

# Vne.  For the Tiger that would amount to about 220 mph.  As far

# as I can determine this is and has always been based on IAS.



It's based on Equivalent Airspeed (23.335), which is essentially the same

thing as IAS for a Tiger (almost no calibration error).



# But read the article by Van's chief engineer about their "theory"

# that Vne is and should be based on TAS.



Wonder why.  In outer space, you could go VERY fast (TAS).  IAS (or EAS) would

be zero, and there wouldn't be any structural damage out there.

923te(at)cox.net
Guest

Posted: Fri Apr 07, 2006 2:59 pm Post subject: Grumman strength

Sure there would be structural damage "out there". Why do you think there 

would not be?

---

FLYaDIVE(at)aol.com
Guest

Posted: Fri Apr 07, 2006 4:59 pm Post subject: Grumman strength

In a message dated 4/7/06 6:59:59 PM Eastern Daylight Time, 923te(at)cox.net 

writes:



 	  Quote: 	
		   Sure there would be structural damage "out there". Why do you think there 

  would not be?

========================
	


HMMmmmm Good question ... I guess you are talking about doing the same test a 

dive?



Well, since there is almost NO friction S&L flight would be WAY above the 

plus 10% on Vne.  It should be already in the 1000's of MPH.  So the test would 

not be needed!  But the big question is What are you going to use for an engine 

and how are you going to get the plane out there?  Is it Out or is it Up?  



The only reason the plane is DIVED is to get GRAVITY to help increase the IAS 

above what the engine can do on its own in S&L flight.  In space, there is 

almost NO gravity to start with.



So, if you do a 60 degree bank in space would there be 2Gs?



Barry

"Chop'd Liver"

923te(at)cox.net
Guest

Posted: Fri Apr 07, 2006 7:55 pm Post subject: Grumman strength

Just put the spacecraft in a spin/tumble  that generates 100G's and see what 

happens....that is after you scrape the pilots blood and other body parts 

off of the inside walls of the craft......

---

GrummanDude

Joined: 15 Jan 2006
Posts: 926
Location: Auburn, CA

Posted: Fri Apr 07, 2006 10:36 pm Post subject: Grumman strength

In a message dated 4/7/06 12:37:38 PM, flyv35b(at)ashcreekwireless.com writes:

 	  Quote: 	
		   That would be an improvement and preclude the expense of installing the

 stainless steel wear sleeve and oversize bearing.=A0 There is plenty of room

 for a wider bearing it seems to me.

 Cliff




	


I've already designed the bracket, getting it approved is a different story.

_________________
Gary
AuCountry Aviation
Home of Team Grumman

david(at)carneyaviation.c
Guest

Posted: Sat Apr 08, 2006 3:51 am Post subject: Grumman strength

I said:



# In outer space, you could go VERY fast (TAS).  IAS (or EAS) would

# be zero, and there wouldn't be any structural damage out there.



You said:



# Sure there would be structural damage "out there".  Why do you

# think there would not be?



Well, it wouldn't come from any aerodynamic force at zero IAS, which is what

we were talking about (the thread concerns Vne).  Where do you think the

damage would come from?

flyv35b(at)ashcreekwirele
Guest

Posted: Sat Apr 08, 2006 8:29 am Post subject: Grumman strength

Actually, design dive speed (Vd) is based on design cruise speed (Vc) and is 

arrived at first and then Vne is typically 0.9Vd.  It's Vd that establishes 

the upper end of the flight envelope.  The aircraft has to be able to 

withstand the limit load of 3.8 g's (standard category) at Vd!  How 

comfortable would you feel flying a Tiger at 222mph and pulling 3.8 g's?



I have not found anyone else or anything written (yet) that substantiates 

Ken Krueger's (Van's engineer) theory about limiting Vne to TAS to preclude 

the possibility of flutter.  The FAA certainly doesn't buy into this theory.



Cliff  A&P/IA

---

gilalex(at)earthlink.net
Guest

Posted: Sat Apr 08, 2006 9:27 am Post subject: Grumman strength

 	  Quote: 	
		  

I have not found anyone else or anything written (yet) that substantiates

Ken Krueger's (Van's engineer) theory about limiting Vne to TAS to preclude

the possibility of flutter.  The FAA certainly doesn't buy into this theory.



Cliff  A&P/IA


	


Cliff... when my German sailplane was certified after being in the country 

10 years (a Mini-Nimbus), one of the modifications required was a marking 

of different redlines (Vne) on the ASI depending on altitude.



Isn't this the FAA requiring TAS to be accounted for, rather than IAS?



.. and with long, flexible wings, flutter is usually the failure mode at 

high speed.



gil in Tucson



PS  Found the manual figures...   New red marks required on the ASI for 

Certification



Alt. (ft.)       Vne (kts)



10,000        135

20,000        120

33,000         96



http://www.schempp-hirth.com/tmdocs/328-6-1427.pdf

PPS  I left the sailplane "Experimental - Exhibition and Racing" - no 

advantage to Standard airworthiness for a sailplane - only 1 US owner 

changed his AW certificate,and that Mini-Nimbus is for rent at Minden, NV.

FLYaDIVE(at)AOL.COM
Guest

Posted: Sat Apr 08, 2006 9:53 am Post subject: Grumman strength

In a message dated 4/7/06 11:55:38 PM Eastern Daylight Time, 923te(at)cox.net 

writes:



 	  Quote: 	
		   Just put the spacecraft in a spin/tumble  that generates 100G's and see 

what 
	


 	  Quote: 	
		    happens....that is after you scrape the pilots blood and other body parts 

  off of the inside walls of the craft......

===============================
	


Sorry ... You NEED GRAVITY to generate G's!

Remember everything in and on a space craft is moving at the same speed.  The 

ONLY way to stop the spacecraft movement is with use of retro rockets.  Or 

have another spacecraft push or pull it in the opposite direction. "A body in 

motion tends to remain in motion unless acted upon by an equal and opposite 

force."



Matter of fact ... Since there is NO AIR in space how do you expect the 

control services to work?  They are just along for the ride.  Replace control 

surfaces with retro rockets.



Remember how Buzz moved around in space?  He used compressed air.  I think it 

was Buzz?



See what happens when you watch too much Star Trek ... Science become 

fleeting.



Barry

GrummanDude

Joined: 15 Jan 2006
Posts: 926
Location: Auburn, CA

Posted: Sat Apr 08, 2006 10:25 am Post subject: Grumman strength

In a message dated 4/8/06 9:30:29 AM, flyv35b(at)ashcreekwireless.com writes:

 	  Quote: 	
		   I have not found anyone else or anything written (yet) that substantiates

 Ken Krueger's (Van's engineer) theory about limiting Vne to TAS to preclude

 the possibility of flutter.=A0 The FAA certainly doesn't buy into this theory.




	


The flight test engineering books from the Air Force don't do it using TAS

either.   But, what do they know.

_________________
Gary
AuCountry Aviation
Home of Team Grumman

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