Thread Tools
Apr 14, 2009, 02:47 PM
Onward and Upward
CatManDu's Avatar
Quote:
Originally Posted by TRC
Sorry to say this, but it flew like crap. Also had a problem with Dutch Roll.
It had a direct drive can motor in it; I retired it before the addendum came out recommending a geared motor. Tail feathers also do not have an airfoil (flat surfaces). The landing gear is just two bent wires wrapped with copper wire and soldered. Two sets of nylon straps are fastened to a plywood support underneath to hold the gear on. The cowl is a balsa build up and hollowed out, then painted.

As for flying it again, I live on a lake year round and fly my Playboy with floats almost exclusively; it's 20 feet to the water so I don't have to go far. I would have to invest in a new power system as well. She looks nice hanging in the basement with about 8 or 10 others I have retired from the eighties.

Tom
Tom,

I'm sorry you had such a hard time with your Sportster. The addendum recommends a direct drive motor. I don't know why, it shouldn't matter. Thrust is thrust, it shouldn't matter where it comes from.
The powerplant for my airplane will be direct drive with extra power, so I can throttle back and enjoy the duration of the system. If I need to climb again and again, there should be no worries. The tail , according to my plan, should be built with a diamond airfoil.
If the airplane is built true; ie; STRAIGHT, it should fly Straight. If not, then I'll have to live with it.
I hope this one will fly well, otherwise, I'll be putting it up for sale!

Randy
Last edited by CatManDu; Apr 16, 2009 at 10:36 PM.
Sign up now
to remove ads between posts
Apr 14, 2009, 03:14 PM
TRC
TRC
Registered User
I only have one problem with your post about putting it up for sale.......... I could put this one up for sale, but if it didn't fly well for me.................. ??????..... That's why it's a "Hanger Queen".

My understanding was it called for a direct drive initially and was changed to a geared. They do fly differently.

I hope you have great luck flying it. It was 20 years ago for me and things have changed.

Tom
Apr 14, 2009, 04:25 PM
Onward and Upward
CatManDu's Avatar

"Modified" 1939 Air Trails Sportster


Well,

Here goes for the left wing construction. So far, so good.

Randy
Last edited by CatManDu; Apr 16, 2009 at 10:33 PM.
Apr 14, 2009, 04:28 PM
Onward and Upward
CatManDu's Avatar

Hanger Queen


Quote:
Originally Posted by TRC
I only have one problem with your post about putting it up for sale.......... I could put this one up for sale, but if it didn't fly well for me.................. ??????..... That's why it's a "Hanger Queen".

My understanding was it called for a direct drive initially and was changed to a geared. They do fly differently.

I hope you have great luck flying it. It was 20 years ago for me and things have changed.

Tom
Tom,

I'm sorry you had so much trouble with it. I hope, with a straight build, mine will fly straight and be a joy to fly. Yours is still is a very good looking airplane.

Randy
Last edited by CatManDu; Apr 17, 2009 at 09:17 AM.
Apr 16, 2009, 10:31 PM
Onward and Upward
CatManDu's Avatar

Modified 1939 Air Trails Sportster


Well,

The left wing is just about done. I have clothes pins on some of the shear webs until they dry. Tomorrow, I'll take it off the building board and trim the wing panel to the outline.

Randy
Apr 17, 2009, 08:59 AM
Registered User
I've got a Sportster plan thats been kicking around for maybe 30 years. I think it's an old John Pond blueline print. The title is "The Air Trails Sportster, Designed by Ben Shereshaw, Wingspan 46", Originally Published in Air Trails, Enlarged by Paul Kastory".

The wing is flat bottom, looks like Clark Y. Stab has a very slight diamond airfoil. 3/16 thick at LE, 3/8 at spar and 3/32 at TE. Stab chord is 6 5/8 at fuse.

Pretty airplane. I'm enjoying the thread and build.

Jim
Apr 17, 2009, 09:06 AM
Onward and Upward
CatManDu's Avatar

Modified 1939 Air Trails Sportster


Jim,

Thanks for the reply. Yes, I do think it's one of the more graceful designs. I think it should fly well and thermal like crazy. It should have a nice gentle landing speed after the modifications I've made to it.

Randy
Last edited by CatManDu; Apr 17, 2009 at 09:19 AM.
Apr 17, 2009, 11:57 AM
How far in the ground..?
Power_Auger's Avatar
Quote:
Originally Posted by Pilatuspc12
Well,

The left wing is just about done. I have clothes pins on some of the shear webs until they dry. Tomorrow, I'll take it off the building board and trim the wing panel to the outline.

Randy
Hi Randy, I'm learning as you go along. You sorted out a misconception I had regarding the shear webbing.

With your slightly thicker constant chord wing mod, it appears as though you will not have any tip washout built in. Is that a correct assumption on my part?

I have decided to add one additional rib bay also. Thanks for the tips.

Ron
Apr 17, 2009, 12:07 PM
Onward and Upward
CatManDu's Avatar

Modified 1939 Air Trails Sportster


Quote:
Originally Posted by Power_Auger
Hi Randy, I'm learning as you go along. You sorted out a misconception I had regarding the shear webbing.

With your slightly thicker constant chord wing mod, it appears as though you will not have any tip washout built in. Is that a correct assumption on my part?

I have decided to add one additional rib bay also. Thanks for the tips.

Ron
Ron,

You're right! I hadn't planned on adding any washout at first. After the initial flight trials if it tends to tip stall, then I will induce a degree or so of washout with the reheated Monokote method!
If you maintain the original airfoil, I would build in a little ( 1 degree or so) washout as per the shim method in the instructions. The Monokote reheated twist method sometimes returns the wing back to its original shape, after time.

Randy
Apr 18, 2009, 10:35 PM
Onward and Upward
CatManDu's Avatar

Modified 1939 Air Trails Sportster


Today was a busy day. The wing center section was deficient, so a new one was envisioned and designed. The design was based on the KISS principal. Keep it simple, sort of. The idea was to make the carry through spars more carry through! The photos sort of show this. The wing will be permanently connected tomorrow. More photos to come.

Randy
Apr 19, 2009, 11:47 AM
How far in the ground..?
Power_Auger's Avatar

Carry through and Carry On.


Hi Randy,

If I'm seeing this right you eliminated the ply dihedral braces. Made up 3 rib W1's, and spaced them evenly to make the center flat wing section.
Does the sheet covering extend to rib W2 (innermost root ribs of the main wing sections) or only the W1 ribs? Regarding the angle for the dihedral, did the main wing root rib ends get the angle applied, or was the inverse applied to the outboard center flat section? The size of your rear bottom spar, is that still 3/16ths X 1/2? It appears larger in the pics.

Thanks for the documentation, pics, and patience!!

Ron
Apr 19, 2009, 12:17 PM
Registered User

Sportster


Is the pic just a fitup for the wing? I do not see the carrythru joiner for the forward spar. Surely there will be one?
Apr 20, 2009, 08:09 AM
Onward and Upward
CatManDu's Avatar

Wing Joiner on "Modified" 1939 Air Trails Sportster


I figured these photos would draw some questions!
These pictures show the preparation of the "fittting" of the angle for the W-1 center section ribs. I've made 3 of them for the modified center section. There will be 2 - 1/8 inch ply wing joiners sandwiched to the top and bottom main wing spars extending out one rib bay into the wings. I'll need to cut all 3 of the W-1 ribs and both wing root ribs to accommodate these joiners.
The aft spar, which is 3/16 X 1/2 inches, will have a joiner epoxied to the front of it as well. This will also extend out one rib bay into the wings.
After joining the wings to the center section with 5-minute epoxy, the center section will be sheeted with 1/16 inch balsa sheeting. I plan on using only 2 inches of dihedral at each wing tip instead of the 3 inches listed. Less dihedral increases lift coefficient somewhat and shouldn't reduce the dihedral effect so much for controllability. Plus, I think it will look better with a little less dihedral!
I'll post more photos for further explanation.


Randy
Apr 20, 2009, 08:17 AM
Onward and Upward
CatManDu's Avatar
Quote:
Originally Posted by Power_Auger
Hi Randy,

If I'm seeing this right you eliminated the ply dihedral braces. Made up 3 rib W1's, and spaced them evenly to make the center flat wing section.
Does the sheet covering extend to rib W2 (innermost root ribs of the main wing sections) or only the W1 ribs? Regarding the angle for the dihedral, did the main wing root rib ends get the angle applied, or was the inverse applied to the outboard center flat section? The size of your rear bottom spar, is that still 3/16ths X 1/2? It appears larger in the pics.

Thanks for the documentation, pics, and patience!!

Ron
Hi Ron,
Yes, this was done inversely because I didn't have the wing root rib dihedral angle template handy when I built the wings. All the sheeting will be butt joined. That sounds funny! Also, I changed the wing dihedral angle anyways. I hope this helps.

Randy
Apr 21, 2009, 08:18 PM
Onward and Upward
CatManDu's Avatar

Modified 1939 Air Trails Sportster


Folks, here is how the wings are connected. It took a while to do this and I had to remove the shear webbing from the wing root ribs but I think this will work.

Randy


Quick Reply
Message:

Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
1939 Air Trails Sportster wallyh Vintage & Old-Timer Designs 17 Sep 07, 2011 08:34 PM
Question Series 50 Air Trails Sportster - Electrified?? Power_Auger Vintage & Old-Timer Designs 37 Sep 16, 2005 06:45 PM
WTB: Air Trails Sportster Series 50,Midway or Cal-Aero Models kg4min Aircraft - Fuel - Airplanes (FS/W) 0 Feb 06, 2005 09:37 AM
The Swallow-1939 Air Trails E-Convert drastic00 Scratchbuilt Indoor and Micro Models 7 Jul 29, 2003 01:18 PM