zoomer199

Well just got back from Maiden flight balanced out per manual. Not good. Had to land using full down elavator. Plane nosed over and fliped on touch down. No damage except for broken prop.
So I think the 3.75 cg is a better starting point and will adjust for that. Sorry I didnt follow Bishops adivice, But with others saying 5.500 was working them what do you do.

bokis

Me being others: We meassured the C.G I used for the flights on the video and it worked great for me..
Sorry to hear abot your flipover,but I really cant understand why yours should behave so totally different from mine..

zoomer199

Ya its a mystery to me also.
How much incidence does your top wing have? Mine measured out at roughly 7deg., that seems like allot to me.
What is the distance from top wing leading edge to your bottom wing leading edge(your top wing could father back than mine). It seems that might be place for a difference.
Its taken me 6 weeks to assemble this bird. I have been very careful to measure 3 times before each cut or glue.
I have had some very experienced scale builders from are club checking up on my work and they have been happy with what I have been doing. So I believe at this point I have done this build correctly.
Again its a mystery, hope others will post as they get there planes in the air. Maybe we will find a pattern to this difference. So we can implement some corrective action.

bokis

Hi again.Didn´t meassure anything when I put this one together,just assembled the wings per manual..I will try to meassure the wings as soon as possible,i guess that you need the meassurements close to the center,the way I can see it this is the only place were we can have done differently,the outher (right word?) struts can only be assembled one way...
But I remeber that I modified the center piece(the metal thing) because i had trouble to get it to fit without "bending" the upper wing..
//Bokis

Edit:Top wing center, rear, straight down in the forward cockpit,3" and center front to the top of the glasfiber cover: 3"..
If I only knew how to make a drawing...[sm=red_smile.gif]
But this may give You a hint if we are close..

FNQFLYER

Ok people, I have just got my box of Swordfish bits (there is a lot) and I got a great deal on a 3M TOC 53cc engine with it. But that is another matter. Questions to all
1/ What is the Cof G that most people consider desireable
2/ I assume all the firewalls are zero down thrust
3/ What is the angle of incidence of both the top and bottom wings.
4/ What is the angle of incidence of the tailplane

Note these readings are taken relative to a neutral thrust angle (measured with an incidence meter of the engine drive shaft.

Reasons for asking
Starting with the tailplane, any varience from neutral can cause an up or down moment input into the flight charastic (just like a fixed elevator)
With the mainplanes (wings) any incidence change from neutral will cause the same effect EXCEPT in the case of a biplane where conflicting (opposite) angles can cancel out each other

After reading all your inputs, all very helpful by the way, I will be going for zero every where (as mentioned above) and working with the 3.75 inch c of g position unless I am convinced otherwise

Also I would like thoughts on the following
Engine Saito 36 petrol
Metal geared servos
JR matchbox to match the 4 aileron servos
2.4 gig radio system probably JR / Spectrum hybrid

Lastly (truly) 3 bladed prop (any ideas where I can get one) and an appropriate scale spinner dome

Thanks guys

Ram-bro

My Feedback: (101)

well I went out to give her the old college try today. I have her balanced as per the plans, assembled the plane.....thank goodness for the removeable wing panels, fueled her up.....and she wont start. Apparently I need to rebuild the carb. Its only been sitting around for about 2 yrs. Sucks to be me.

zoomer199

Thanks Bokis this might help decifer the diffrence.Get back to you in a day or two when I can get back out to my shop.

zoomer199

I see where you are going with this. most of us built per manual using the jigs provided. Doing that gave large incidence in top wing. no one knows if this is correct or not. You may find like in my case the tail peices just dont fit good and you will have to scab them together best you can. The saddle for the tail was not level side to side on mine. Yours may be the same. Since we have no incedence # for tail or wings its just a guessing game.

ispirit99

Do you think the "tightness of the flying wire's" has anything to do with this situation? I think it was TY who mentioned that the Wire's really were ment to function to keep the wing from shifting in flight. It was also stated that there is no mention in the manual about how important the wire's are. Just a thought. Tony.

FNQFLYER

Setting incidences, assuming you do not have any other data:
Lesson 1 draw a line from the tail to the front of the engine (prop shaft).
(Assuming you have zero down or up thrust, you must check the firewall at this time to ensure that it is vertical if not adjust the engine thrust to zero).
This is the thrust line and a datum line,
Now level the aircraft to that line.
Setthe Tailplane to a zero value (that is level) and in line with the previous line drawn, this will give you a zero angle of incidencefor the tail plane
Nowset your mainplanes to zero as well keeping the aircraft level. Now theincidences and thrust line are all at the same value.

Lesson 2 To adjust for an a/c that tends to climb either adjust the mainplane by packing the the trailing edge (not practical in this case) or packing he leading edge of the tailplane.
You should be able to work out the rest from there.
In case you were wondering where these pearls come from,I am a licenced a/c engineer (mostly Boeing types) who has a couple of DH Tiger a/c restorations undermy be;lt and have assisted in the build ofan RV4 (1:1 scale) and I have used all of the aboveon those a/c and in trimming out my competition OldTimer A/c

Variations from the above (especially with the tailplane horizontal stab will cause the severe up and down pitch you lot have been having as willexcessive positive angle of incidence on the top wing.

I haven't looked into the flying wire thing yet but any movement of the top wing will cause flight degradation at least

Just some thoughts guys hope they help

ispirit99

FNQFLYER, as we say here in West Virginia, "sounds like you know your Bean's and Tater's". Good thing I'm going slow on this assembly. Looking forward to getting her to fly right. This thread has been very helpful toward that end and all of the contributions have been food for serious thought. I am enjoying the heck out of this assembly and keep watching for the next post. Ram-bro, sorry to hear things have not worked out. I think you are very close.

FNQFLYER

Ok guys, I have looked at the "book of words" that has come with this beast and I note that there is positive incidence on the tailplane (l/e nose up).  This should give a down moment so there would appear to be some problem with the mainplane incidence (probably to much) given the data presented to date
So with the above in mind level the a/c using your trusty Robart incidence meter on the tailplane and then proceed as previously advised.
I am puzzled about the method of attachment of the top main plane (seems to have lots of incidence) but will explore this further as my build actually starts and progresses.
A final note though, with the a/c leveled as indicated above the firewall should be vertical if not adjust the engine thrust line to a zero value, that should stop the rapid transition to climb that some have experienced
Trust this helps, I am watching and learning before I start my build.

Robert Bishop

HI Folks,
Have spent the last 2-days on the Swordfish -rigging and CG location.
First Cg-Taking into account the upper wing sweepback,(3.63 DEG.) 25% of Mean Aerodynamic Chord= 3.757", which when projected back to the plan center section gives a distance back from the L.E. of 4.652"

Tailplane incidence=+3 deg.
Top wing incidence=+3.5deg.
Bottom wing incidence= +4 deg
Engine downthrust=0 deg.

I think these angles are too large and this along with the balance point at 5.118" (as per manual) are responsible for the crash on take-off.

I have designed and built other scale biplanes- notably a Fairey Fantome (1/5 scale ) and a Curtiss P-6E Hawk (1/4 scale). Both have incidences much closer to zero deg.

Will re-rig the Swordfish to the following-

Tailplane incidence=0 deg.
Top wing incidence=+1.0deg.
Bottom wing incidence= +1.5 deg
Engine downthrust=0 deg.
CG- 4.652" at center section.

I also had the control throws set as per manual and feel that these throws may be too large-will cut them down.
Sorry for the confusion re the CG-hope this clears it up.

The Fantome plans are available from Jerry Bates-in case someone may be interested.
I also found a 20 mm dia carbon fiber tube for the lower wing.

Let me know what you think of my conclusions.


Bob Bishop

zoomer199

Will been flying and trouble shooting this bird all weekend. Here is a brief recap.

First flight:
CG set to manual. Very tail heavy managed to land it but flipped at end of runway. No damage.

Second flight:
Moved CG to 3.75 by adding 5lbs to nose using a tempory tray attached to standoffs of motor. I flew! but seemed nose heavy. Still need a lot of down trim to maintain level flight.
Flipped again at end of runway. no damage.

Third flight:
Removed 1lb of weight putting CG at ????. (same trim settings)...Flew much better and had a enjoyable flight,... until a rich low end condition caused the prop to cease rotation. Had to land it in the tall weeds. No damage.

Fourth flight:
Tuned motor and added more ele throw (1/4more than manual). much better. Flight felt solid in the air and very predictable. Finally had a good landing..Ya!!! Tail wheel is way to weak, to much bounce action.

I have a DL55 (0 deg down thrust) on her and she was fast. hard to slow it down for landing. However was running with no cowl

So things to change for next flights in the future:

Change tail wheel wire to 5/32. Should help bounce and nose over.
Prop down motor to 22x8 (was 22x10) or purchase smaller motor. Adding the cowl may help also slow it down.
Change wheels to 5 inchers. Should help nose over. Provided wheels look to small anyway.
Don't care for how much down is needed but it is what is at this point.
Will continue to run the temp weight tray until more reports come in. Bishop holding out for what you results are.
I am guessing that the new CG is about 4 1/4 I will get a good measurement later this week as time permits.

If one where to read all the different ESM model Threads a common them is that CG per the manuals are 1 inch back farther than needed. A friends LA 7 was same way, watched him almost dump his in do to tail heavy condition.

FNQFLYER

To Robert Bishop (and Zoomer 99)
All your data good to read however I would caution against a radical change of the wing and tailplane incidences and I would only do one at a time starting with a change in mainplane incidences starting with the top wing. My thoughts would be to reduce the top wing to 2 degrees and the bottom to 2.5 or even 3 degrees, then play with the tailplane. You can overcome the tailplane incidence (during test) withdialled in down trim.
I think the tailplaneincidence could be the cause of the nose overs (given the speeds this a/c appears to be operating at)
I personally thinkthat a 50cc engine is wayto much, the POM's are using Saito 36's or near equivalent, and with regards to weight better positioning of the radio gear, ignition system etc should take care of a lot of that problem. I will be using what are heavier scale wheels.
Are you guys flyingthe a/c with the torpedo fitted??
Just as an aside I am reading a book about Air Racing in the US during the period 1920's to 1970 called Wet Wings and Drop Tanks, and I note that Wiley Post when he was flying the Lockheed Vega reduced the mainplane incidence (for greater speed) andthen dropped the tail by shortening the tail wheel post to increase the effective incidence for take off, interesting idea thatworked well
Any way I am watching with great interest and appreciation, keep up the good work

ispirit99

I am going to use a Zenoah 38cc on mine with a Brison muffler and the torpedo. Thinking after the CG issue is settled, I would trim her out before I fly the torpedo. One less factor to weigh while trimming. I have the Dubro 5+" inflatable wheels that give her a nice stance and should work well with the shocks. I set up my tail wheel the same as someoneon this thread did. [sorry I forgot who it was but I think it was Ty ]. It's a much nicer wheel and I used the plated tail wire provided with the kit. This thread has been a big help and thanks to you "brave Test Pilots" for helping the rest of us have a better chance to really fly our Swordfish without finding out theflaw's to late.Guess I will start on my cockpit kit.

Ram-bro

My Feedback: (101)

one thing yo think about when mountiing the G38 is to ensure you have access to the spark plug. The torpedo will get in the way so maybe either a removeable torpedo or mouunt th motor at a slight angel

ispirit99

Thanks for the heads up. Do we know if the fire wall is at "zero" or set up with the correct side and down thrust? I'm also wondering how to decide how far forward or back I need to mount the torpedo so it won't effect the CG. How close are you to finishing your repairs and was itmore or less damage than you first thought. Thanks, Tony.

Ram-bro

My Feedback: (101)

dont think the torpedo will haqve that much effect on the cg as long as it is. i was more concerned with getting it mounted straight and centered. As soon as I can get a rebuild kit for my muffler.........

FNQFLYER

Ok guys after much searching (and importantly verification) here is the "standard incidences" for full size 1:1 a/c. I emphasise that these are base reference points and each a/c is modified from there to give the charastics that the "driver airframe aka pilot" desires.

Top wing 0 degrees, bottom wing +1 degree, tailplane -0.5 to + 1.5, nominal + 1.0 degrees. These were the starting figures for 2 x Tiger Moth's I assisted in rebuilding and my old Qantas mate assures me that they are the nominal settings for the Avro Cadet that Qantas apprentices rebuilt

Combine that with zero down or side thrust for the engine and a nominal C ofGthat is approx 20to 25% of the overal M.A.C. then you will have thestarting pointsrigging the a/c

It might be beneficial to get onto the Royal Navy Historical flight to find out the rigging figures for their Swordfish that they use for flying displays, after allthe model shouldn't vary much from the full sized data

fockewulf37

My Feedback: (102)

Ok Guys just adding to the onfo. Mine is ready to fly. SO i will have to bite the bullet and try it soon. Anyway I built the plane per the manual. I used the jigs they supplied. I have not put an incidence meter on the plane until tonight. Here is the way mine came out.

With the fuse set at Zero.
I have 1 degree positive on the top wing
I have 1 degree positive on the bottom wing and also 1 degree positive on the horizontal. I did not check on the motor thrust yet...

Ty

fockewulf37

My Feedback: (102)

I had to widen the piece to fit the motor. My motor is set at ZERO....

Ty

MANFRED

My Feedback: (27)

Ty, how bout some pics?

FNQFLYER

Ty, see my previous posts, but that would appear to be as good a starting point as any. My last post was quoting the data points for setting the incidences on biplanes as per my apprentice training manuals, back in the dark days when gas turbines were just a thought (well almost) to us youngsters.
As an aside I wonder how many people building these ARF's (if you can call them that) have actually built a model fron scratch or a kit. I learnt a long time ago that anything on a model (or full sized a/c) that fell to earth when released from any height was "bad" and as such my modelling has been a constant search for the lightest components I can find (well all most).
Why is that relavent here?? The fact that people are adding pounds of lead t the nose is the main one. No one has mentioned the positioning of all the moveable components (batteries, ignition units, servos etc), all of which can and should be positioned to save weight, the best C of G adjuster I have found has been the batteries. Things like nose spinners (engine spinners) can be made a bit heavier and given their position at the front of the a/c a little extra weight here goes a lot further that a lot more further back for the same net effect, metal mounts are another one, mandatory for my 4 strokes and petrol engines (more rigid and also heat soaks)
To finish off a couple of examples I will be using on this model, metal mount for the FG36 (Saito supplied and recommended), A box behind the engine mount to house the ignition system (probably will mount the engine onto the box if I can get away with it, depends on cowl clearence etc) and I will mount the radio batteries against the firewall under the fuel tank (it will be a 500ml tank). That will put allmy moveable weight forward and hopefully reduce theneed for additional weight if not eliminate it entirely.
Lastly I will move the servos forward if I deem it necessary but I will mount the 2.4 gig radio well away from all of the above
Another option is toput a radar dome on thefront but that will be extreme but never the less an option
Like I said make all weight useful and not parasitic
Just some ideas guys and I am still watching and learning.
BTB how much does Ty's cockpit weigh?? I am going to get one regardless

ispirit99

Good Luck on your test flight Ty. Hope you have perfect flying weather. While on the subject of Incidence, anyone have any thoughts on the best Digital read out Incidence meter? I don't see the small print like I use to.