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Airspeed indicator marks

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resto108
Reputable Member

Going through my 1947 GSM, (not the pitiful spiral bound thing you can buy now) and the picture of the airspeed indicator, page 114 if you have one, shows the usual Vne's and two other radial red lines. One at 88 for flaps marked "P", "the maximum safe speed for gliding with flaps down and power off", and another one at 100 marked "G". No mention of what its for or what G means. Anyone ever seen a G on an airspeed indicator or know what its for? There is no reference to it in the spiral bound GSM, nor can I find one in the Owners manual. The closest I can come is 102 mph for Vno seaplane.

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Topic starter Posted : 30/08/2021 8:45 pm
Carsten H.
(@carl)
Trusted Member

I'd seen that and wondered the same thing.

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Posted : 30/08/2021 9:13 pm
Will Ware (Webmaster ISC)
(@stinsono)
Member Admin

Look in the AFM for your specific aircraft if you still have it, it will have all that info. 

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Posted : 30/08/2021 10:18 pm
Carsten H.
(@carl)
Trusted Member

Still looking for that one. All I can come up with is the plastic bound univair operating manual which does not mention what resto108 is talking about. I had just thought it might have been a misprint. 

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Posted : 30/08/2021 11:35 pm
Will Ware (Webmaster ISC)
(@stinsono)
Member Admin

Look in the AFM. here is a link to mine https://app.box.com/s/plr1185yif3wf3kkyhrnocfl05qkhz6n

 

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Posted : 31/08/2021 2:12 am
Carsten H.
(@carl)
Trusted Member

Thanks, I bookmarked it. Still don't see any reference to  the 100 mph white arc shown in the original GSM.

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Posted : 31/08/2021 3:48 am
resto108
Reputable Member

No reference to 100mph or a G on the ASI in my 1946 Operation Limitations either.

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Topic starter Posted : 31/08/2021 12:48 pm
Carsten H.
(@carl)
Trusted Member

Took some pics from my GSM today:

IMG 20210831 135851
IMG 20210831 135931
IMG 20210831 140111

 

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Posted : 01/09/2021 5:25 am
Carsten H.
(@carl)
Trusted Member

Took some pics from my GSM today:

IMG 20210831 140111
IMG 20210831 135931
IMG 20210831 135851

 

 

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Posted : 01/09/2021 5:49 am
resto108
Reputable Member

Mine does not have that section. It has 1947 on the cover, so it only covers -0 and -1. Instead, it has this text:

IMG 0851

I contacted Univair for the drawing, since Stinson went to the trouble of putting a Stinson part number on a standard part. They probably had US Gauge manufacture them with the range marks on the face. Hopefully the drawing is available and it tells the story.

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Topic starter Posted : 01/09/2021 6:17 pm
lawheelock
Prominent Member

Guys and Gals,

This reference to two different airspeeds for flaps comes from your original operation limitations document.  If you do not have it in your aircraft records, you can find it near the end of Airworthiness in the FAA CD disc for your airplane, which if you do not have it, you can get it from the FAA site.

Here is a pasted copy of the one for my plane, a 108 .  I have seen a similar document for 108-1s and 2s.  Over the years many airspeeds have been replaced and the non Stinson A&P neglected to make sure the airspeed was properly marked.  The operations limitations document does not specifically say to mark red lines, but that is what should be done.

 

Larry Wheelock

 

image

Larry Wheelock, A&P/IAStinson 108 N584LW 180 LycTexas in Winter; Indiana in Summer

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Posted : 07/09/2021 4:31 am
resto108
Reputable Member

Well thanks for solving that mystery! The text of the GSM is backwards. P is power on flaps down, not power off flaps down. They went to all the trouble to put it in italics, too!

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Topic starter Posted : 07/09/2021 11:21 am
Will Ware (Webmaster ISC)
(@stinsono)
Member Admin
Posted by: @lawheelock

That is great @lawwheelock, I have my original AFM but I’m not sure this specific page is still in there. I will look though 

 

Here is a pasted copy of the one for my plane, a 108 .  I have seen a similar document for 108-1s and 2s.  Over the years many airspeeds have been replaced and the non Stinson A&P neglected to make sure the airspeed was properly marked.  The operations limitations document does not specifically say to mark red lines, but that is what should be done.

 

Larry Wheelock

 

image

 

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Posted : 07/09/2021 6:21 pm
Carsten H.
(@carl)
Trusted Member

This has been an interesting discussion. My A/S indicator looks very original but is missing the red radial lines and the P and G markings, and the white arc ends at 88mph. I've read an account about stress to flap hinges using flaps above the limit with full power during climb can cause. Also makes me wonder about the need for flaps at 100mph power off.

 

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Posted : 07/09/2021 7:03 pm
lawheelock
Prominent Member

The operating Limitations document is not in the flight manual.  It is a part of the original aircraft records and if you don't have it get the FAA CD and print out a copy.  You about have to use a computer with a DVD/CD drive to display and print.  Stupid smart phones don't have the capability.  P is for power on 88 mph.  G is for glide, power off 100 mph.  Helps when descending from altitude.

Larry Wheelock

This post was modified 1 month ago by lawheelock

Larry Wheelock, A&P/IAStinson 108 N584LW 180 LycTexas in Winter; Indiana in Summer

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Posted : 08/09/2021 2:57 am
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