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Re: extended baggage?
Posted: Mon Jan 09, 2012 6:19 am
by ak2711c
Each one I have installed has fit exactly as you discribe. I doubt my method to make it fit is Selkirk approved but I sanded a little on the outside corners where they are hitting the rivits, this allowed it to sit down in the bulkhead a little better. Then I used large area washers as spacers between the bulkhead and the ears on the baggage floor. The rear fasteners for the floor go through the washers to hold them in place. You will find that you will also have to trim quite a bit off of the rear baggage wall they give you in order to make it fit as well. Good luck.
Shawn
Re: extended baggage?
Posted: Wed Jan 11, 2012 5:19 pm
by blakelewis
In the CG discussion It seems that the Center of Lift is being overlooked. The center of lift is the fulcrum not the firewall. Loosing weight behind the firewall and in front of the Center of Lift will move the CG forward, but you will need less tail down trim. Instead if you were to toss out some baggage you have again move the CG forward but you have removed weight from behind the center of lift and now need less tail down trim.
From the observations of having a heavy tail with loss of fuel means the center of the fuel is in front of the Center of Lift.
Re: extended baggage?
Posted: Wed Jan 11, 2012 5:26 pm
by GAHorn
blakelewis wrote:In the CG discussion It seems that the Center of Lift is being overlooked. The center of lift is the fulcrum not the firewall. Loosing weight behind the firewall and in front of the Center of Lift will move the CG forward, but you will need less tail down trim. Instead if you were to toss out some baggage you have again move the CG forward but you have removed weight from behind the center of lift and now need less tail down trim.
From the observations of having a heavy tail with loss of fuel means the center of the fuel is in front of the Center of Lift.
Did you not mean to say that losing wt aft of firewall/forward of C/L ...results in AFT C/G movement, and therefore less tail-down trim?
And...if one removes wt aft of C/L (and also aft of firewall) .... results in forward C/G movement...and therefore requires more tail down trim.
Re: extended baggage?
Posted: Wed Jan 11, 2012 6:06 pm
by blakelewis
George,
I was confusing the issue with examples. This is the simplest statement that I could come up with:
Remove weight from in front of CL and tail goes down, but if the weight was removed from behind firewall, CG moved forward.
And a simpler example:
I think they call the point we measure from the Datum point, which in our case is the firewall.
Divided the plane up into three sections: Forward of Datum, Datum to C/l, and Aft of C/L.
C/L is the fulcrum; the Datum is not the fulcrum.
Slide weight aft or forward the balance changes in the direction you slide along with CG.
Remove weight from section Datum to C/L, CG goes forward, but the balance changes to the rear.
Re: extended baggage?
Posted: Wed Jan 11, 2012 9:52 pm
by GAHorn
The "datum" is merely an arbitrary point along the longitudinal axis of the airplane. It can be anywhere the engineers want to place it for a reference point. (In some aircraft, it's not even ON the airframe at all....but is some point out in space ahead of or behind the airplane. An example is the King Air 200/300 series in which the datum is actually 89.5" forward of the forward jack-point, placing it in front of the aircraft about 6 feet.) It doesn't matter. If wt shifts FWD or AFT relative to the datum, the CG also moves in that direction.
However, the effect that has on inflight pitch-trim is relative to the C/L....not the datum.
Re: extended baggage?
Posted: Fri Jan 11, 2013 12:22 am
by Abe
Back to the actual extended baggage design of Mike Petrie's. Richard, the photo you posted in '09 doesn't show the back of the baggage compartment. Do you have a photo showing it. I sure like the tie down attachments and the short sides on Mike's kit as I have an ELT mounted back there also.
Re: extended baggage?
Posted: Fri Jan 11, 2013 3:24 pm
by hilltop170
Bill-
The plane with Mike's extended baggage is in Alaska, I am in Texas. I will be in Alaska Jan 22 and can take a picture at that time if you can wait.
I fabricated my own rear panel with the first extended baggage that was installed (which was removed when Mike's ext baggage was installed). It is a two-piece panel, a top and a bottom that are independently removable. If I carry long items like pipe or lumber, I just remove the bottom.
- MLJ Aircraft extended baggage
Re: extended baggage?
Posted: Fri Jan 11, 2013 4:15 pm
by Abe
Richard,
A photo would be great and I talked to Mike yesterday and he said that his doesn't come with the back panel. Boy, sounds like January is a bit early to be heading back north.
Thanks Again...
Bill
Re: extended baggage?
Posted: Mon Oct 29, 2018 3:52 pm
by goneflying
Has anyone modified a 170A in order to make an extended baggage work? i.e. moved the cables to run like the 170B?
Re: extended baggage?
Posted: Mon Oct 29, 2018 6:40 pm
by pdb
I just put a Selkirk Aviation extended baggage kit in my 170B. It’s very nice. Their website says it fits in all 170 series planes. It’s worth a call to see if it’s an easy installation in an A model.
https://selkirk-aviation.com/extended-baggage-kits/
Re: extended baggage?
Posted: Tue Oct 30, 2018 2:19 am
by ghostflyer
When I was in Ontario last I was inspecting a 170a who had a extended baggage fitted. It wasn’t a STC but a bootleg but done very well. It had been done similar as a 170b would be done but the floor had been raised up to clear the cables and pulleys .a thin aluminium form ,square in shape had been built around the cables and pulleys that travel from the floor to the roof centrally . While this is a small obstacle when fitting goods into this area but the owner claimed he could put his golf bag in there . The sound proofing fitted on the sides of the fuselage was a black foam with a aluminum foil stuck to one surface but the damage to the sound proofing indicated that more than golf bag had been transported .
Re: extended baggage?
Posted: Mon May 08, 2023 3:57 pm
by Wyoming1
Bruce Fenstermacher wrote:Well I finally looked at this W&b problem. George I think you are confusing the issue with your aft trim statement. I know I had to read it twice.
As George and others have said the CG moves forward as fuel is burned. Below is my W&B sheet with a graph that shows a typical 2 adult front seat loading in my plane. Full fuel is indicated by the green dot, no usable fuel by the red triangle. With the simple fuel loading information given us from Cessna, drawing a line between the dot and triangle would show the CG path from full to empty. (this is not the case with aircraft with more sophisticated fuel systems).
Picture 4.jpg
Just guessing at the arm of an extended baggage area I added 20" to the 95" arm of the normal baggage area to arrive at 115". This might not be the actual arm but close enough for this. The W&B sheet below places the 20lbs max at that arm. There is no other change between the first W&B sample and the second so you can see how far just this 20lbs would shift the W&B.
Picture 5.jpg
I've attached these sheets before for all and they are also available at our members page. If you find anything wrong with them let me know. They've been given out for nearly ten years with only one small fix so I believe they're accurate.
48-170_WB.xls
170_A_or_B_Model_WB.xls
170_A_or_B_Model_WB_with_Javelin_Tank.xls
Bruce I am dealing with this issue as well now. Your documents show as no longer available? Where might I find the cg limits for a 170a? Trying to plug my info into foreflight, but it has a 'pre-canned' for and aft limit and I'm not certain they are accurate?
Re: extended baggage?
Posted: Sat May 13, 2023 4:35 am
by pdb
Re: extended baggage?
Posted: Sat May 13, 2023 12:19 pm
by Bruce Fenstermacher
Wyoming1 wrote:Bruce Fenstermacher wrote:Well I finally looked at this W&b problem. George I think you are confusing the issue with your aft trim statement. I know I had to read it twice.
As George and others have said the CG moves forward as fuel is burned. Below is my W&B sheet with a graph that shows a typical 2 adult front seat loading in my plane. Full fuel is indicated by the green dot, no usable fuel by the red triangle. With the simple fuel loading information given us from Cessna, drawing a line between the dot and triangle would show the CG path from full to empty. (this is not the case with aircraft with more sophisticated fuel systems).
Picture 4.jpg
Just guessing at the arm of an extended baggage area I added 20" to the 95" arm of the normal baggage area to arrive at 115". This might not be the actual arm but close enough for this. The W&B sheet below places the 20lbs max at that arm. There is no other change between the first W&B sample and the second so you can see how far just this 20lbs would shift the W&B.
Picture 5.jpg
I've attached these sheets before for all and they are also available at our members page. If you find anything wrong with them let me know. They've been given out for nearly ten years with only one small fix so I believe they're accurate.
48-170_WB.xls
170_A_or_B_Model_WB.xls
170_A_or_B_Model_WB_with_Javelin_Tank.xls
Bruce I am dealing with this issue as well now. Your documents show as no longer available? Where might I find the cg limits for a 170a? Trying to plug my info into foreflight, but it has a 'pre-canned' for and aft limit and I'm not certain they are accurate?
The links to the spread sheets are still good here:
viewtopic.php?f=26&t=10379
Re: extended baggage?
Posted: Tue May 16, 2023 2:25 am
by jklaerner
ghostflyer wrote:When I was in Ontario last I was inspecting a 170a who had a extended baggage fitted. It wasn’t a STC but a bootleg but done very well. It had been done similar as a 170b would be done but the floor had been raised up to clear the cables and pulleys .a thin aluminium form ,square in shape had been built around the cables and pulleys that travel from the floor to the roof centrally . While this is a small obstacle when fitting goods into this area but the owner claimed he could put his golf bag in there . The sound proofing fitted on the sides of the fuselage was a black foam with a aluminum foil stuck to one surface but the damage to the sound proofing indicated that more than golf bag had been transported .
Below is an image of a 170A up in Alaska. It was advertised for sale several months ago and the add stated an extended baggage option. When I inquired, the seller sent me a few pictures and said it was a Selkirk kit for a B model that he had field approved. As seen, there is a tunnel built around the cables. I believe the useful load was placarded as 20 pounds (same as a B model). Again the CG limit is the key when going that far back.