Design

DoctaDave
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Re: Design

Post by DoctaDave » March 10th, 2015, 11:28 pm

bernard wrote:If you're using the Freedom Flight kit or using plastic tubing/straws to attach your wing posts, how are you attaching your plastic tubing/straws to your motor stick? I've tried using CA and of course it doesn't bond well since its plastic. I've used tape and its worked well but I would like a more secure and permanent solution, possibly one I could do without buying cement.
It says in the kit instructions to sand the sides of the straws which helps the glue to adhere to the plastic

nxtscholar
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Re: Design

Post by nxtscholar » March 11th, 2015, 4:23 am

Expanding on DoctaDave, you should be taking sandpaper and scratching the surface of these plastic tubes. The reason is that it will increase the surface area of the tubes and allows for more surface to be bonded.

I use CA instead of model cement. Works fine.

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Re: Design

Post by jander14indoor » March 11th, 2015, 4:44 am

bernard wrote:<SNIP redundant quote of my message>
I don't quite understand your descriptions because I'm not good with visualizing some things. I attached a diagram with a side view. Do you think this would be allowed, and would it benefit flight?
It SHOULD be allowed, in my opinion, because as you slide the gage up, it moves back since it is measuring the distance from LE to TE at that location.

Additional example. While almost everyone uses straight wings, there is nothing stopping you from using swept back wings (other than they provide no advantage at these speeds). If you did the PROPER way to measure chord is along the direction of flight, NOT perpendicular to the LE and TE.

Benefit, probably not at a detectable level. Drag MAY be a little lower, I don't see any other benefit and you should get almost the same benefit with a vertical trailing edge to that tiplet.

But it does look pretty.

Jeff Anderson
Livonia, MI

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Re: Design

Post by Less_Incidence » March 12th, 2015, 3:32 pm

I read through some of this thread that I missed and I too was having some similar problems with the Freedom Flight kit struggling to climb, et cetera. I discovered that the plunging roll that happens is partially due to the plane not having enough wing warp, but is also a stability problem. Even when I added up to 8mm of washin in the left wing of my plane, it would still climb about two feet, dive about three feet, then return to a normal climb. This was a problem even for low ceilings, as the plane didn't climb very well in the first place, and I couldn't get it higher than about 17'. It turns out, the tail incidence that the FF kit has was the cause of this climbing issue. Also, I was having an issue with the plane stalling on very low torque. When I reduced the incidence or moved the CG forward, the plane struggled to climb at all, but at the incidence and CG position needed for any sort of climb, the plane would have stalls in its descent.

I made two and a half major modifications to the Freedom Flight plane to fix this:

First, I added tip dihedral to the wings. Each wing has about 1" of dihedral, put in by slicing the wing spars with a razor blade just past the last wing rib before the wing's edge, cracking the balsa, and re-gluing it at the upward angle. I left the stock tip plates on (Now they're tilted inward rather than being vertical), as I think they help with stability in addition to the dihedral. This immediately solved the problem of the plane rolling hard left and diving in on launch.

Second, I constructed a new fuselage with a different tailboom. (Motor stick remained the same.) I made sure that the horizontal stab was now flat relative to the propeller thrust direction instead of having the weird upward angle that the stock FF kit has. The plane climbs much harder and much better now - I only need about .6 in-oz of torque on .094 rubber to get it up to a 22' ceiling, in comparison to my older 1.0 in-oz needed to get it anywhere above 15'. Once, I wound it hard to about 1.0 in-oz with a good piece of 5/99 Tan II in a 35' smooth-ceilinged room and it was bashing away at the ceiling for a solid 30 seconds. Probably could have climbed another 50' - I'd really like to see it in a good Cat III site. That flight time was nearly four minutes.

The new fuselage, in addition to the straightened stab, also now has about 2 1/4" of droop in the tail boom. The reason for this is that it keeps the tail out of any turbulent air coming off of the wing - the vertical separation between wing and tail is now about 4". This allows the tail to do its job a bit better - that is, provide more lift to the rear end of the plane. This both assists in keeping the plane from nosing up too hard in the climb (for low ceilings) and also solved my problem of low-torque stalling.

Right now, after my old 2:30-consistent plane got smashed in an accident involving a couple of cats, this plane is flying about 2:20 no-touch flights in a 22' gym. I'm guessing I can probably play with rubber and props and get it up to 2:40 consistently. Not exactly a national-champion time, I know, but it's still a much better flyer than any of the FF planes I saw at my regional last weekend.

I'll probably post a few pictures of my modifications in the next couple of days.

Hope this helps!
2015-16 Events: (CMHS Invitational/Southern CO Regional/CO State)
Wright Stuff: //
Chem Lab: //
Electric Vehicle: //
Bridge Building: //

Lewis-Palmer High School class of 2016

retired1
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Re: Design

Post by retired1 » March 13th, 2015, 6:29 pm

A thought-
Anyone that actually has 5/99 rubber does not need a kit.
As in any free flight event, practice and knowledgeable small changes separate the 1 min flight from the 3 min flight. It is kinda hard to badmouth the FF design because a number of people are having flights of over 3 min. It is a basic kit. Each plane has a personality.
One of our girls made her first flight today that was actually quite good on 800 winds. Moving the wing back 1/8 inch made a beautiful flight Un fortunately, it was in the rafters with several collisions and then lost a battle with the basketball net which threw it into the wall. Did not time it, but it was well over a min on 800 winds. So, the design can not be all that bad. Need to tighten up the turn and she did not have enough prop offset, so I think that it is going to be competitive with a bit more practice.

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Re: Design

Post by calgoddard » March 14th, 2015, 8:23 am

I agree with retired1.

Dave Ziegler's 2015 FFM kit is excellent. With proper building, trimming and winding, you could win any WS competition with it.

I have built, flown and coached indoor duration stick models for ten years. The Wright Stuff team I coached this year won their regionals with a custom design. It was the only airplane out of 48 teams that was not the 2015 FFM kit airplane. I'd like to think that the design differences were partly responsible for the win. However, I know for a fact that the arch rival of the school I coached flew the same time as my teams' gold medal flight in a practice flight with their 2015 FFM kit airplane.

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Re: Design

Post by Less_Incidence » March 14th, 2015, 9:47 am

Yeah, that flight with 5/99 was a complete one-off, I borrowed a piece of rubber from a local indoor flyer. It's not like I have ready access to the stuff, and I don't imagine many other wright stuff flyers would either. The plane still does nearly as well on TSS though. (Just as a clarificiation to anyone who's reading this: 5/99 is a batch of Tan II rubber from May 1999 that is considered ideal for indoor flying. The rubber that most of us use is newer Tan Super Sport.)
Initially I had my own design, but again after it got destroyed by my cats I was in an emergency situation and didn't have materials to build another one, so I ordered something I could put together quickly before regionals.
I don't have anything against the FF design in itself nor am I trying to badmouth it, I'm just describing the issues I was having with it that seemed to be common problems. Being in such a non-competitive region, my regional-gold-medal time of 2:15 beat the next best flight by more than 30 seconds, which was a stock FF kit. However, I did see one team fly over 3 minutes in a practice flight - with a stock FF kit - just before I did officials. They must have catastrophically broken something on their plane, otherwise I would've been beaten by quite a large margin.
2015-16 Events: (CMHS Invitational/Southern CO Regional/CO State)
Wright Stuff: //
Chem Lab: //
Electric Vehicle: //
Bridge Building: //

Lewis-Palmer High School class of 2016

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Re: Design

Post by Toms_42 » March 15th, 2015, 10:00 pm

Worst possible feeling... last flight after three hours of testing too... Time to whip out the backup planes I guess; regionals are in 3 days.

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(sorry for potato quality, digital zoom doesn't work too well)
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Re: Design

Post by bernard » March 15th, 2015, 11:33 pm

Toms_42 wrote:Worst possible feeling... last flight after three hours of testing too... Time to whip out the backup planes I guess; regionals are in 3 days.
[img]http://i.imgur.com/KZBMvXp.jpg?1[/img]
(sorry for potato quality, digital zoom doesn't work too well)
Oh no! How high up is it?
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Re: Design

Post by nxtscholar » March 16th, 2015, 3:34 am

Have you tried using a helium filled balloon to retrieve it?

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