Today's Message Index:
----------------------
1. 02:57 AM - Re: cut steel parts (Jack T. Textor)
2. 03:29 AM - Re: Pietenpol-List Digest: 20 Msgs - 09/12/07 (Douwe Blumberg)
3. 03:45 AM - Re: neat tool (Gene & Tammy)
4. 03:49 AM - Re: High Speed taxi (Gene & Tammy)
5. 04:12 AM - Re: High Speed taxi ()
6. 11:39 AM - Re: power at low rpm (Tom Winter)
7. 12:50 PM - Re: Re: power at low rpm (Max Hegler)
8. 01:33 PM - Re: Re: power at low rpm (FTLovley@aol.com)
9. 02:36 PM - Re: Re: power at low rpm (Patrick Panzera)
10. 03:53 PM - Re: Re: power at low rpm (Greg Chapman)
Message 1
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Thanks to all for your thoughts. I plan to tack then have the welding
instructor at a local school finish it up.
Thanks,
Jack Textor
www.textors.com
Subject: Re: Pietenpol-List: cut steel parts
In a message dated 9/12/2007 5:20:24 PM Central Daylight Time,
eng@canadianrogers.com writes:
I believe Chuck Gantzer is using MIG to tack his
Tailwind fuselage together (for ease of use), then completing
the final
welds using a torch.
Having said that, I have also read that several production
aircraft have
used MIG welded 4130 structures.
Anyone else out there with more knowledge about this stuff?
Bill C.
That is correct, Bill. Tack weld with Mig, then finish with Oxy / Accy
is a common procedure, but keep in mind you must completely weld through
the original tack weld. Using this method there is less stress induced
into the steel tube structure.
At the Rans Factory, in Hays KS, I understand the entire fuselage is
welded up using Mig Welding. It is great for a high rate of production,
but I wouldn't recommend it to the home builder. Keep in mind these
guys do a LOT of welding, and I think that even with their expertise,
there is still some undue stress induced into the airframe.
Chuck G.
NX770CG
________________________________
See what's new at Make AOL Your Homepage.
Message 2
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| Subject: | Re: Pietenpol-List Digest: 20 Msgs - 09/12/07 |
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Message 3
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Dick, A very exciting time for you. Be careful and keep us advised.
Gene
----- Original Message -----
From: Dick Navratil
To: pietenpol-list@matronics.com
Sent: Tuesday, September 11, 2007 8:20 PM
Subject: Pietenpol-List: neat tool
I have been wrestling with my new 3 piece wing, trying to get it
correctly aligned and to put in the proper washout on the tips. Today I
stopped in Sears and found a level with a digital read out to the tenth
of a degree. It also has a laser. I was able to fine tune the wings
and the $50 was well worth it.
Also, I had final airworhyness inspection on friday and passed. I'm
hoping for first flight this weekend.
Dick N.
-------------------------------------------------------------------------
-----
9/11/2007 5:46 PM
Message 4
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| Subject: | Re: High Speed taxi |
Congratulations Chet!
Gene
.
9/12/2007 5:22 PM
Message 5
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It was just a matter of time b4 you figured it out.Sounds
fantastic;congratulations,enjoy many more flights!
________________________________
From: owner-pietenpol-list-server@matronics.com
[mailto:owner-pietenpol-list-server@matronics.com] On Behalf Of Chet's
Mail
Sent: September 12, 2007 10:37 PM
Subject: Pietenpol-List: High Speed taxi
I would like to take this time to thank Dick Navratil, Catdesign, Gene &
Tammy plus Jim Ash. As of today N920Y has flown once again. Mr. Hicks
would be proud of his little airplane and she preformed well.
After checking out every ones ideas as to my problem, I had asked a
fellow pilot to come and taxi the aircraft and give me his thoughts.
Before he was to show up I give a fellow pilot his Byannual flight
review in his A model Cessna 170. After a couple of take off and
landings and a great flight review.We started the Piet up for him to
hear run. After a couple of minutes he said it is to nice of a evening
to just stand here go do some taxi testing. So I did. After a couple of
runs down the runway, I added a little more power and every thing just
felt right. So we turned her around into the wind and added full power.
Now that is a great felling when she lifts off the runway. On down wind
the schroud around the radiatior came loose, so we had to cut the flight
short.
The biggest problem was I was just not getting up enough speed to have
good airflow over the tail.
Once again thanks to every one for your input.
Chet
Message 6
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| Subject: | re: power at low rpm |
I stole this from the physicsforum. The contributor is "Danger " [I
always use my actual name for a username], but I believe "Danger" has
got it right. The question came up here a few days ago:
(On the matter of Undersquare/oversquare)
Where they differ is in how that power is produced. As a general
rule, a 'stroker' (undersquare) makes its maximum hp/torque at lower
rpm's. An oversquare motor of equal displacement can make the same
amount, but you might have to rev it three times faster to reach the
power band.
Since we're interested in prop efficiency, we -- of course -- want
our muscle at low rpms. I.e., bigger bore, shorter stroke.
BTW, For any gearhead, mathfan, physicsforum[dot]com might be worth
signing up in.
Message 7
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| Subject: | Re: re: power at low rpm |
Tom,
I always thought a "stroker" was an engine with an increased stroke.
And an engine that had been "bored and stroked" had been bored to larger
diameter cylinders and a new crankshaft added to increase stroke.
Either or both of these treatments are meant to increase the airflow.
The result would add horsepower at the same rpm or provide the same
horsepower at a reduced rpm.
So I would think we would want bigger bore and/or longer stroke...
Not a Physicist...:)
Max
----- Original Message -----
From: Tom Winter
To: pietenpol-list@matronics.com
Sent: Thursday, September 13, 2007 1:38 PM
Subject: Pietenpol-List: re: power at low rpm
I stole this from the physicsforum. The contributor is "Danger " [I
always use my actual name for a username], but I believe "Danger" has
got it right. The question came up here a few days ago:
(On the matter of Undersquare/oversquare)
Where they differ is in how that power is produced. As a general rule,
a 'stroker' (undersquare) makes its maximum hp/torque at lower rpm's. An
oversquare motor of equal displacement can make the same amount, but you
might have to rev it three times faster to reach the power band.
Since we're interested in prop efficiency, we -- of course -- want
our muscle at low rpms. I.e., bigger bore, shorter stroke.
BTW, For any gearhead, mathfan, physicsforum[dot]com might be worth
signing up in.
Message 8
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| Subject: | Re: re: power at low rpm |
To get power at a lower RPM, we would want MORE stroke, not less...such as
the Curtiss OX-5 which is 4 inch bore by 5 inch stroke and develops its 90
horsepower at 1400 RPM...at least that's the way I see it.
Forrest Lovley
Jordan MN
**************************************
See what's new at
Message 9
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| Subject: | re: power at low rpm |
For those who think that torque is king and direct-drive is the only way to
go, I have several hundred hours in an SEL aircraft that has an engine
capable of making the same maximum torque as an O-235.
The plane is capable of hefting 10,495 gross to 26,000' with an initial
climb rate of 1,575 ft/min and cruises at 270 kts. (true) up in the flight
levels.
The prop is driven through a geared redrive that knocks the output of the
23,000 RPM turbine engine down to a manageable 1,750, operating the 105"
4-blade CS prop at 76% of mach (while doing 270 kts).
The HP rating at either the input or output of the PSRU is in the 1,000
range (actual HP is predicated on engine temperature), so for me, the 1,000
HP rating is WAY more relevant than the anemic 228 ft/lbs of torque the
engine makes at 23,000 RPM.
Torque x RPM 5250 = HP
Pat
Message 10
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| Subject: | re: power at low rpm |
Ohhhh, Pat, that's so misleading. That redrive is also a torque multiplier.
What's the torque value at the output side of that unit? Whatcha flying, a
Caravan?
For the record, 23k RPM is pretty enthusiastic and characteristic of a
modern small turbine. Many Low to Mid bypass turbines max out at just shy of
11,000 RPM and are limited to these speeds by air temp, air press and
inertial mass. Didja know that turbine inlets are designed to control 3
things? Temp, air pressure and air speed. The air speed in the inlet of a
supersonic machine can't be allowed to go transonic, the temperature should
be close to freezing and pressure shouldn't exceed 2 psi. I should be more
modest, though. These were the design rules in place for equipment back when
I was still working on them. Breaking one of those rules resulted in
compressor stalls, flaming inlets, etc.
For a conventional fire maker in an airplane, torque is indeed the key to
maintaining inertia.
The primary reasons folks avoid gear reduction in lighter aircraft with more
modest powerplants are the same as they've always been: weight and
reliability. They weigh a lot when they are properly strong enough to
support the loads represented by a 7'-12' flywheel moving at speed. And it's
easier to make a reliable gear drive for a turbine since there are no
combustion pulses being transmitted to the input end of the unit, unlike a
conventional IC engine.
And for the record, I wish I could say I had several hundred hours in the
machine you describe. It sounds interesting...and expensive. ;)
Greg Chapman
http://www.mousetrax.com
http://www.layer1wireless.com
"Don't start with me or I'll
replace you with a small and
efficient script!"
> -----Original Message-----
> From: owner-pietenpol-list-server@matronics.com [mailto:owner-
> pietenpol-list-server@matronics.com] On Behalf Of Patrick Panzera
> Sent: Thursday, September 13, 2007 4:36 PM
> To: pietenpol-list@matronics.com
> Subject: RE: Pietenpol-List: re: power at low rpm
>
> <Panzera@Experimental-Aviation.com>
>
> For those who think that torque is king and direct-drive is the only
> way to
> go, I have several hundred hours in an SEL aircraft that has an engine
> capable of making the same maximum torque as an O-235.
>
> The plane is capable of hefting 10,495 gross to 26,000' with an initial
> climb rate of 1,575 ft/min and cruises at 270 kts. (true) up in the
> flight
> levels.
>
> The prop is driven through a geared redrive that knocks the output of
> the
> 23,000 RPM turbine engine down to a manageable 1,750, operating the
> 105"
> 4-blade CS prop at 76% of mach (while doing 270 kts).
>
> The HP rating at either the input or output of the PSRU is in the 1,000
> range (actual HP is predicated on engine temperature), so for me, the
> 1,000
> HP rating is WAY more relevant than the anemic 228 ft/lbs of torque the
> engine makes at 23,000 RPM.
>
> Torque x RPM 5250 = HP
>
> Pat
>
>
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