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Feb 01, 2015, 11:56 PM
wrong descision, wrong time
Quote:
Originally Posted by basicguy
Wind has been 15-20 all day.
Build one of these:

https://www.rcgroups.com/forums/show....php?t=1383516

I've flown one of these in 15-20 mile an hour winds. Its a lot of fun to watch it "hover" right in front of you. I've had great luck with the kfm* airfoils in very windy, turbulent air.

Its also a good easy flyer on lighter days too

Heath
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Feb 02, 2015, 07:38 AM
Laughs at un-boxing videos...
basicguy's Avatar
Hi Heath,
Am building a "one sheet glider" from Springer's plans. I took the 5x60" KF2 wing and stuck it on my smaller Oshkosh. It flew fine. Needed more speed than the airfoil wing. My Oshkosh will almost hover in a 10 mph wind.

My bigger Oshkosh needs more power. Have had a few flights with it but it had to be full throttle all the time. Am getting a 3s battery for it.

The 300 sq in kf airfoil was decidedly lighter than the Armin wing.
Mar 02, 2015, 05:08 PM
Laughs at un-boxing videos...
basicguy's Avatar
I have added ailerons to my Oshkosh 40 Sport. My first attempt had to much flex in the .032" wire linkage and it made amazing sounds in gentle dives. Since fixed.

My 60" Oshkosh is a real slow flier It has a 205 watt motor and a 3 cell battery.

It went on a diet losing 3 oz, but still weighs a pound and a half.
Sep 10, 2018, 09:52 AM
Registered User
Hello,

I managed to finish my oshkosh sport. This is my second build after the oshkosh special. Sadly, the first build crashed almost instantly (I assumed it ended up being too heavy). This second build, however, turned out better. The thing is I can't fly it.

Attempt #1: hold the plane with my hand and try to throw it while raising the throttle. The plane flew some meters (almost straight). Then, as I pulled on the elevator, the plane went up and to its left, crashing upside down.

Attempt #2: tried to take of from the ground. I might have given it too much throttle, because it went up, flew straight for about 1-2 meters, until i pulled the elevator again. This time it didn't capsize, it went up a bit, but still wanted to go to its left. I cut the throttle and it crashed into its nose, at about a 45 degree angle (on concrete).

Attempt #3: right after Attempt #2 the screws that had held the motor in place came out a bit, and I didn't manage to screw them back in tight (the holes in the plywood got damaged) and the motor was hanging down a bit (it was still in its place, only with a downward deviation). However, I did try to at least taxi the plane a bit to see if I could control it. There is a tendency to go to the left and there is some delay between the stick movement and the plane actually listening. While taxiing, the plane performed well, in the sense that when enough throttle was applied, the tail would raise above the ground almost on its own, waiting for me to pull on the elevator. During this attempt, I was increasing the throttle with very, very little increments.

So what am I doing wrong? I think during the first two attempts I was giving the plane a bit more throttle than I should have. And as a second mistake, I think that I might be pushing and pulling the sticks more violently than I should.

Thanks!
Blue
Sep 10, 2018, 02:02 PM
Foamy and Glider fanatic
Blacky's Boy's Avatar
Try limiting your elevator and aileron throw to about 60%. Also put some DR & Expo on the Aileron and Elevator. I found this worked well for me to tame planes that were notoriously "touchy"
Sep 12, 2018, 04:53 AM
Registered User
Quote:
Originally Posted by Blacky's Boy
Try limiting your elevator and aileron throw to about 60%. Also put some DR & Expo on the Aileron and Elevator. I found this worked well for me to tame planes that were notoriously "touchy"
Thanks for the tip! I'll try both to see how it behaves.

Blue
Sep 12, 2018, 08:52 PM
Registered User
elewon's Avatar
seems like you need right trim which is normal for tractor planes. Also check the CG to make sure it is not tail heavy.
BTW, too much throttle is actually good to get out of stalls or difficult situations during take off.
Sep 13, 2018, 08:21 AM
Registered User
Quote:
Originally Posted by elewon
seems like you need right trim which is normal for tractor planes. Also check the CG to make sure it is not tail heavy.
BTW, too much throttle is actually good to get out of stalls or difficult situations during take off.
Is that because of the factors described here (I'm referring to the need to right trim)?
Sep 13, 2018, 08:29 AM
RC Adddict
Wilfor's Avatar
Have you done any chuck tests with it into long grass to see how it glides ?

Do you have someone that can get it up and trimmed for you ?

Being an aileron plane you will have to fly it as it won’t self correct. Ailerons, rudder could need trimming inflight. Perhaps a little down and right angle to the motor to help compensate for motor torque ?
Sep 13, 2018, 08:56 AM
Registered User
Quote:
Originally Posted by Wilfor
Have you done any chuck tests with it into long grass to see how it glides ?

Do you have someone that can get it up and trimmed for you ?

Being an aileron plane you will have to fly it as it wonít self correct. Ailerons, rudder could need trimming inflight. Perhaps a little down and right angle to the motor to help compensate for motor torque ?
The only control surfaces are the rudder and the elevator. There are no ailerons involved. No, I haven't done any chuck tests to see how it glides, but I might do some after I fix the plywood firewall at the front. The CG was (if I remember correctly) at about 3-5cm behind the attack surface of the wing, so I guess it is not tail heavy. I need to get it up myself, at least for now, as I usually try to fly it alone.

Blue
Sep 13, 2018, 10:30 AM
Foamy and Glider fanatic
Blacky's Boy's Avatar
I learned to never underestimate the usefulness of the glide test. There is patch of high grass at my club's flying field that I use just for that purpose.
Sep 13, 2018, 10:55 AM
Registered User
How is the glide test actually performed? Do you guys simply toss your planes and hope for the best?
Sep 13, 2018, 12:38 PM
RC Adddict
Wilfor's Avatar
Sorry I assumed ailerons I read kfm in the first post and went from there.

I reread your first post and it could be as simple as to much input on your part. The UC wing will fly at a nice slow speed with very little input needed to control. If you pull back to hard it could pitch up and left like youíve described.

For the chuck test I usually just kneel so Iím say 3 feet off the ground and in front of nice soft long grass and then give it a gentle over hand toss like throwing a paper airplane. Adjust the trims until you get a decent glide with no pitching up. Youíll be amazed how far the darn thing can actually glide.
Sep 13, 2018, 12:43 PM
Foamy and Glider fanatic
Blacky's Boy's Avatar
I like to do my test glide under power with the throttle cut engaged. That way I can see how it reacts to input
Sep 13, 2018, 03:39 PM
Registered User
Quote:
Originally Posted by Wilfor
Sorry I assumed ailerons I read kfm in the first post and went from there.

I reread your first post and it could be as simple as to much input on your part. The UC wing will fly at a nice slow speed with very little input needed to control. If you pull back to hard it could pitch up and left like youíve described.

For the chuck test I usually just kneel so Iím say 3 feet off the ground and in front of nice soft long grass and then give it a gentle over hand toss like throwing a paper airplane. Adjust the trims until you get a decent glide with no pitching up. Youíll be amazed how far the darn thing can actually glide.
No problem! I actually wanted to use a kfm-3 wing, but in the end I went for the classic wing.

I assume the glide should be smooth? So the plane shouldn't dive with its nose in the grass, but rather maintain a smooth trajectory?


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