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Old Jun 28, 2014, 05:34 PM
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United States, WA, Mt Vernon
Joined Jun 2014
46 Posts
Help!
Annnddd Crash! Help!

Finished this a couple weeks ago and finally had a decent day to fly.



since I had a few days to tinker with it, I got the balance set and did several test glides. Those went very well. or so I thought.

When it comes to models I love making them, when it comes to flying I am absolutely terrible at understanding how to properly trim for powered flight.

Today the wife and kids tagged along for its maiden powered flight and this was the result. Clicking the picture should load the video.



Any assistance on what went wrong and how to possibly remedy it would be great. I need to repair the firewall which was removed by the impact but that was the only damage! I am thinking it needed some more downthrust, but I could be way off track there.

Thanks and don't laugh.
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Old Jun 28, 2014, 07:42 PM
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United States, TX, Spring
Joined Jul 2010
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I saw no inclination (pun) to turn, which would convert the nose up tendency into a spiral climb (hopefully).
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Old Jun 28, 2014, 08:39 PM
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Gold Coast Australia.
Joined Jan 2005
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More downthrust and prop. on backwards might help????????????
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Old Jun 28, 2014, 10:05 PM
I'd rather be flying.....
United States, IA, Story City
Joined Oct 2013
338 Posts
If the test glides were fine, then add downthrust a bit at a time..... prop on backwards like gossie said can really help too...

If test glides are not fine, fix the glide before trying power again, IMO.

Best Regards,

Jeff
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Old Jun 28, 2014, 11:03 PM
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United States, WA, Mt Vernon
Joined Jun 2014
46 Posts
Thanks for the great suggestions guys!

I'll be repairing the firewall presently and do as you say.

Think some side thrust would be in order as well? Or shall i use the rudder for that?
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Old Jun 29, 2014, 12:22 AM
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Gold Coast Australia.
Joined Jan 2005
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Quote:
Originally Posted by MiZer1981 View Post
Thanks for the great suggestions guys!

I'll be repairing the firewall presently and do as you say.

Think some side thrust would be in order as well? Or shall i use the rudder for that?
Be careful using rudder, as it can take over.
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Old Jun 29, 2014, 08:46 AM
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Needs downthrust and right thrust and could probably stand having the prop on backwards.
I would guess about four degrees of down are in order.
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Old Jun 29, 2014, 01:11 PM
B for Bruce
BMatthews's Avatar
The 'Wack, BC, Canada
Joined Oct 2002
11,164 Posts
You've got two things going on.

The first is that the model has TOO MUCH pitch stability. You need to move the balance point back a little and reset the tail to restore the glide. You want to keep doing this in small amounts of moving the balance back and adjusting the tail incidence until when you deliberately push the model out for a test glide into the proverbial tall grass that the model has a long and fairly gentle stall. As it is now if you were to push it with a firm glide toss it would nose up to a stall fairly quick like.

All in all I'm thinking that you'll end up with the balance about 1/4 to 3/8 inch behind where it is now.

The reason you want to do this is so that the added flying speed from the engine running will not cause the nose to rise so much. By adjusting the amount of pitch stability via this balance point and tailplane setting change you'll minimize the amount of down thrust you need. But you'll still need SOME added downthrust.

For turn size you again want to set the glide first. If you can test glide it at a place with a long gentle sloping rise. The slope will extend the glide and give you more time to see what is going on. Set the glide for a nice flying speed and adjust the rudder for about an 60 to 80 foot glide circle to the right. Once set do not play with the glide settings any more for balance, tailplane incidence or rudder setting.

Instead you're going to use down and right thrust to adjust the climb to get a 50 to 60 foot right circle in the climb and adjust the downthrust to get the model to climb at an angle that sees the model flying at the roughly the same speed as it flies in the glide.

I like to set up my models with a crossed up trim so that the for a right hand circle that the right hand wing has a little washIN angle. That's right, I warp the inboard wing to have a little higher incidence angle at the tip. The rudder is then adjusted to force the model to turn to the right. A little washin, about 2 to 3 degrees worth at the tip, aids in holding the inside wing up if the model wants to try to steepen into a spiral dive. It also works well to quickly dampen out a run away, ever increasing series of stalls.

So that's about it. Move the balance back a little then adjust the tail to restore the glide. And warp in a 2 to 3 degree amount of washin on the right wing panels. Test glide on a long sloping area to get a long enough glide to let you set the rudder for an 80 foot glide circle. Using some thin washers stack to washers under the upper left screw and one each under the upper right and lower left to give you some down and right thrust. Test fly with only a few seconds worth of fuel left in the tank and the prop turned around so it's got the curved face to the rear. If the initial flights look good use more fuel for longer runs. If those look good and you want more climb then turn the prop around so it's on the right way.

The PeeWee engine runs for about 2 minutes. One way to reduce this easily without needing to measure the fuel all the time is to put a few glass or plastic beads into the tank. A nice motor run for a model like this is around 1 minute. A minute gives you enough time to get the engine started and make any last second adjustment and then launch. By the time you've done all that you should get up to around 40 to 50 seconds. And if you're wanting less it's not that long to hold it to reduce the run time in the air.
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Old Jun 29, 2014, 02:49 PM
Branjo
Joined Sep 2013
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cool plane!
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Old Jun 29, 2014, 03:51 PM
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The windy west coast of Sweden
Joined Sep 2008
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Quote:
Originally Posted by bshultz327 View Post
cool plane!
Agree !
It resembles the "Snoopy", published in M.A.N, dec/56.



/EDIT/ The plan is now uploaded (..forgot it...)
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Last edited by Gluehand; Jun 29, 2014 at 06:02 PM.
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Old Jun 29, 2014, 04:25 PM
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United States, WA, Mt Vernon
Joined Jun 2014
46 Posts
Thanks BMatthews! I grew up in chilliwack,, I should just bring the plane to you when i come see my folks next. Lol

Thanks for the compliments on the plane! I got the plan from outerzone. Called bipe buggy. Perhaps a bit ambitious for my first scratch build in 15 years.
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Old Jul 06, 2014, 09:44 PM
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United States, WA, Mt Vernon
Joined Jun 2014
46 Posts
Got the bipe repaired and fixed a couple things before trimming like suggested.

Got a good flight in, and by good I mean it did a complete bank around me but didn't gain any altitude before spying the ground and landing rather hard.

I think I added too much down thrust. Next flight it nearly hit my wife while banking and decided to call it quits on the bipe before I end up with another ex wife.

Switched to some gliders for the rest of the outting. And tried my teedee .020 powered glider with rather poor results, too much right thrust and broke the fuel tank upon landing. Went like stink tho.

Oh, and I put my pinkey into the prop at full throttle.
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Old Jul 07, 2014, 08:34 PM
B for Bruce
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The 'Wack, BC, Canada
Joined Oct 2002
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Provided you added enough washin on the right wing then you used a little too much right or maybe a little too much down. Or by the sounds of it a little too much of both. Perhaps see if you can find or make some thinner washers. Got a set of calipers to measure the ones you've used already? I'd go with some that are about 20% thinner. You're likely very close so this will be a suitable change to try.

Ideally I like my power pattern on a sport model to be the same size as the glide circle. But if you have to open it up so the power climb circle is a LITTLE bigger in diameter that's not so bad.

If the bank started out OK and got tighter that means you don't have enough washin on the inside (right) wing. Or it may be that your vertical fin is simply too big for the amount of dihedral for this design. Try some more washin twist and watch what the circle size is like and if the bank increases.
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Old Jul 07, 2014, 08:49 PM
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Joined Nov 2012
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A touch of left rudder tab will pick it up and keep it from hitting you in the back.
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Old Jul 08, 2014, 02:13 AM
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United States, WA, Mt Vernon
Joined Jun 2014
46 Posts


Here's a vid of the best flight. The advice you guys are giving def helped! I'll adjust my washer situation and washin and try again. Won't beable to fly for a couple weeks since I'm leaving to Hawaii on Sunday.

Rudder was straight on this flight.

This is my other plane. Looked promising had it flown upwards and not down with a bit less bank.





Thanks again for the advice guys.

I hope to have videos of beautiful lazy circles in a couple weeks.
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