If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
Thread Tools | Display Modes |
#21
|
|||
|
|||
On Fri, 23 Apr 2004 09:45:33 +1000, Mike Borgelt
wrote: On Wed, 21 Apr 2004 11:57:40 +0100, Martin Gregorie wrote: On Wed, 21 Apr 2004 10:02:05 +1000, Mike Borgelt wrote: Generally pitot and static probes/ports are much more sensitive to sideslip than are good TE probes.(Good TE probe = Irving type two hole probe ) Mike, just a quick question: My ASW-20 is fitted with a fin mounted Irving-type TE probe except that it only has a single hole in place of the usual two holes. What advantages would there be to swapping it for a two-hole version? Martin, While I have seen wind tunnel data that suggests that the suction around the rear 180 deg of the tube is constant there do seem to be variations and the two hole probe may be less sensitive to sideslip. Also: Many years ago now just after the Irving probe design became available I built one in 1/4" tube and one in 3/16" tube and a Nicks(single hole type)in 3/16" as per Oran Nicks drawings. I then flew my Mini Nimbus with a second ASI connected to probe and pitot. I checked the two instruments against each other and applied static system corrections to the readings of the normal ASI and reckoned I could get down to an error band of +/- 4%. I had had a feeling that the Nicks tube was under compensating and the test showed it to be short of suction by 20% and a little more at low speeds. The Irving probe made per Irving was within my error band and the 3/16" Irving was a little short on suction getting worse at low speeds leading me to conclude that there may be a Reynolds number effect for the low airspeeds and smaller diameter tubes. Interestingly Nicks recommended the hole 2 x tube diameters from the end and Irving said 1.5 Current Irving type tubes have settled on about 1.67 as the hole distance from the end and the holes are closer together than on the original Irving design and 6mm or 1/4" tube is used. Mike Borgelt Thanks, Mike. That's exactly what I wanted to know. -- martin@ : Martin Gregorie gregorie : Harlow, UK demon : co : Zappa fan & glider pilot uk : |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Not to sound like an F-22 cheerleader but I thought this was interesting. . . | Scott Ferrin | Military Aviation | 96 | June 5th 04 04:24 PM |
"I Want To FLY!"-(Youth) My store to raise funds for flying lessons | Curtl33 | General Aviation | 7 | January 9th 04 11:35 PM |
Cleaning a 3-way TE probe | Jack Glendening | Soaring | 37 | November 5th 03 06:45 PM |
I wish I'd never got into this... | Kevin Neave | Soaring | 32 | September 19th 03 12:18 PM |
Question of the Day | M B | Soaring | 16 | September 10th 03 07:30 AM |