Coug___

Suggest you consider moving the CG.

CG location and downtrust have different effect (different results).

Zor
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Any idea of where the proper CofG location is? Motor is heavier than what was recommended, but I pulled a lot of weight with the stock painted cowl.

well finaly made it back on.. got my new shop done and ready to get back to building again.

Should have read more[&:]. Went back into the instructions online and found my CofG was indeed further back than recommended. Never like adding useless weight, (ie, not control or power system related), but had to bite the bullet and scarf some lead to the firewall. Will tap the Heavy Hub to 7 X 1 at work tomorrow and hopefully be able to try again this weekend.

Was able to get a couple of flights in last evening to test the CofG and motor incidence changes. Seems more pitch stable cutting through the wind, but still has the tendency to yaw a lot. May experiment with one of my heli RATE or HH gyros for the heck of it. If I keep the snap roll in for one full revolution it has the tencency to continue for 1/2 revo more once I center the controls, so there must be some inertia there. Learning where to cancel it if I want to finish the same attitude as I started.

Inverted still requires NO down elevator or the nose will climb. Even on low rates there is enough elevator to do inverted circuits or an outside loop if I wanted, (not yet). Was able to remove the slight down elevator trim.

Exhaust adapter arrived today, so can get back at mounting the cowl, but currently sick as a dog, so will have to wait.

Had mounted the keychain cam at the paying passenger hole, but the prop blast was a bit more than the velcro mounting could take and have the raster scan from the prop. Will have to think up a better mount or location.



[youtube]http://www.youtube.com/watch?v=8E5HtWp_E1A[/youtube]

cougar 429 and all fliers,

Just remember guys that there is mass in our models and inertia.

Many maneuvers initiated also have to be teminated by contolling just as we initiate the maneuver.

If you use ailerons to establsh a banked attitude then you need opposite ailerons to stop the roll at the desired angle of bank.

Just neuralizing the control does not stop the bank. You are likely to over-roll and result in a nearly vertical bank and a great loss of altitude in the turn and then have to climb back up.

This kind of thing also applies to many maneuvers. Try to practice "smooth flying". Assure that the model is well balanced laterally as well as longitudinally. This applies to dynamic as well as static conditions. Understand the effect of CG placement and the effects of downtrust and side trust in terms of how you wish your model to perform.

If all you want is tear holes in the sky than none of this may be necessary. Just install an engine/motor that has lots more trust than the weight of the model and enjoy.

The important thing is to enjoy the hobby in your own way.

Have fun.

Zor

I understand fully the effects of mass and inertia. Just commenting this one continues further beyond anything else I have.

Most of my other A/C will stop a roll or snap as soon as I neutralize the controls, (my friends Ultimate does EXACTLY what you ask of it). I have a few other bipes in the queu, including a PICA WACO I just grabbed that needs a bit of work, so perhaps one with 4-ailerons will behave differently.

Since I have been getting more aggressive, pushing the boundaries as I work on the list of maneuvers, just found something that could have come out to bite me the next flight.

Was doing the final fitting for the cowl and went looking for a sound that has been bugging me from day one. There has always been a bit of a rattling sound coming in flight, something along the lines of a couple of pieces of wood colliding. Had mostly come to ignore it, concentrating on trying to tame the rich midrange on the Saito and thinking it had to do with the more pronounced power pulses of the 4-stroke. Last Sunday the friend I had been teaching to fly brought it to my attention again, so this time tried to find the source. Only thing I saw was a bit of play between the forward cabane attach and upper wing. Pulled it apart and was thinking of adding a bushing when I noticed the tab extremely weak. One more slight flex and it broke off! The rear was not far behind, so glad I made the effort.

Pulled the entire cabane assembly apart and will bring it to work tonight to bead blast the joint area and look into making more substantial tabs with holes that more closely fit the C/F rod I use to pin it together. Was always leery of how thin and weak those tabs were, (why, with such heavy rod they opted to use something so thin and soft?) so hopefully this will eliminate that one complaint. Now if I could only find a stronger main gear that fits the last of the buggaboos would be flushed.

Phew!

Luck was on your side in finding the weakened tab.

The instruction and build manual shows two options for the cabane. One is to attach the cabane permanently (fixed) and the other is to make it removable. The fixed cabane only has one forward and aft mounting tab (1/32" brass - yep, way thin!) while the removable option has four of the mounting tabs. When you remove the paint from the cabane (if the original builder followed the plan) you'll see that the brass tabs are soldered to the cabane wire. My guess for Sig using the thin brass tabs is to make soldering-up the cabane easier for the builder, i.e.: easier to get sufficient heat using a "hobbiest" weight soldering iron/gun.

As far as the gear, one of the two "bolt kits I have came without the main gear. I ordered a new one from TNT Landing Gear Products (http://www.tntlandinggear.com/) made from T-6 aluminum. Pricey ($45) but great quality and beefier than the stock gear.

EJWash

You're right about price! What P/N did you get?

Actually, I mailed them the main gear from my second kit back in May 2009 and they duplicated it. Now that I look at my e-mail correspondence with TNT, the gear was $35 plus $10 shipping. The Sig gear is .091" thick and the TNT gear is .121, and the Sig gear is 84 grams versus 108 grams for the TNT. So, you get a bit beefier gear going with TNT.

I did e-mail Sig before I went with TNT. The Skybolt gear was no longer available. They did suggest using the 4-Star .60 main gear, but I'd have to cut it in the middle cross-wise and widening it to fit the Skybolt's fuselage width. The Skybolt's gear is 4-1/2" wide on the flat where it mounts to the fuselage. I wasn't really wide about doing that so that's why I went with TNT. The 4-Star .60 gear $10 plus shipping from Sig. Not sure it's thickness, but if it's the same .091" stock as you (may) have on the ship now, you're right back where you are now. TNT does make replacement gear for the 4-Star, but at the same price as you'd pay for the custom Skybolt gear order.

I'll see if I can dig-up the invoice and order number.

EJWash

Well, even though I've been sick this week and spent most of the day in bed, got back to work on the 'Bolt this evening. Soldered on the new tabs, made from some very tough copper electrical hardware from my bits at work. Had to widen the troughs in the wing to accomodate the thicker material and most of the work consisted of getting the alignment correct. Now have a VERY close fit with the C/F rod and no more noticeable motion between the wing and cabanes.

Rather than the standard copper wrap I opted for stranded nichrome aircraft wire. Just as easy to solder, but much stronger. May redo some of the rather rough looking original brace joints this way later, before fitting some form of aerodynamic cover or sleeves. And that brings a question; The cabanes were a slide fit into the fuse. Were they originally to be bonded in?

Now the 90 degree adapter is installed, finished the fitting of the Fiberglass Specialties cowl. Relocated the augmenter flange further forward and finally mounted the remote fill, (glad to stop yanking and installing the fuel line with needle nose). Still have to do some fill and will double layer the area around the motor cutout, but bolted on for now and will test fly it to check any cooling issues first. Only other item is to anchor down the plastic crankcase vent line and maybe look at a rudder gyro. Just hate pulling the wings off again[:'(]!

Pics did not turn out the best. I'll try with better lighting tomorrow.

Like I mentioned, there are two options for the builder to either name the cabane fixed (bonded in place) or removable (see pics). Looks like the original builder went with the fixed cabane option.

Your cabane tab fix looks great. Can't see it going anywhere, and much thicker than the 1/32" tabs.

Still poking around for the TNT invoice, are you still interested or thinking of another avenue?

EJWash

Think of bracing the gear with wire. We'll see.

The pic of the Skybolt on the kit box shows a brace on the main gear, but it is not mentioned in the build manual nor is it depicted on the plan sheet. I included a pic of one 'Bolt with the brace. Guess it's up to the imagination on this one.

There is a piece of 3/8" balsa that is glued between the main gear between the gear that fairs-in with the bottom of the fuselage. Your 'Bolt's original builder had the option to make access holes to the gear attachment bolts to make the gear removable.

Just for idea's sake, my 1/4-scale Hostetler 'Bolt kit landing gear came with a 3/4"-wide by 1/8"-thick aluminum brace that fits beneath the main gear in an inverted 'V' and attaches to the middle of the main gear and wheel axles. The center of the brace rides on a spring to allow dampening of the gear's flex (see pic). I don't think this spring necessary for the Sig 'Bolt. A single 4-40 'J' bolt can hold the wire at the top of the 'V'. I can't see needing more than 1/8" music wire here.

EJWash

As promised, here are some better lit pics. Did the gear bracing. We'll see how it holds up and affects ground handling.

Hoping the wind will die a bit and let us go flying this evening.

VERY nice!

EJWash

Did not have a lot of luck. Could not get the motor to run right, slugging along until I had a deadstick when I dropped the throttle on final. Figured the fill valve was leaking when I tried several times to get the mixture set. Motor became VERY hot.

Pulled the cowl and ran straight to the carb, but motor kept dying after a few seconds at full throttle and on the last one it seized![&o]
High speed needle did not make as much change as I thought, but there was enough smoke to make me think it was not lean.

Pulled it apart when I got home and the con rod was pretty jammed onto the crank pin, with signs it rubbed against the rear cover[X(]. Pulled it off and could not fine anything visible, so lubed it up and worked it back and forth till it felt better. Reassembled the motor and had to do a minor adjustment on the intake rocker, but other than that could not account for this behavior. Wondering if when the motor heated up so much it prevented lube from making it down into the case.

Only real difference was the 90 degree adapter, which I sincerely hope does not strangle the flow so much I get inadequate scavenge.

On a good note, the plane tracked well and handled the dead stick perfectly.

That's a bummer.

I've only test stand run an OS FS-91 with the angle adapter installed. No problems at idle, transition to high speed or back to idle. But that's on the stand only. Hope you find a solution.

EJWash

Been doing some reading and think I may have a couple of suspects. I tried leaning out the low speed needle to deal with the rich mid range and may have leaned it out too much, (even though I did the typical trick of following any adjustments with one on high speed). Apparently when you get close the adjustments can be very tight.

The other reason is perhaps the fuel inlet may have had some crap or the O-ring could have deteriorated, clogging the carb. Will have to now check the tank and blow out the carb.

Lastly, really don't know the seizing when I had it smoking quite a lot, but some of the suggestions for cowled engines means I may have more work ahead of me directing air to the cylinder. To be honest I should have run it with the systems as they would be for flight and the cowl off, rather than the complete setup, to check function before buttoning it up. Too many changes at once on a new and unfamiliar setup usually means any problems are that much harder to trace. Comfortable on new 2-stroke installs since I have so many years experience, but my first 4-stroke has proven some tricks don't carry over. Sure hope this is not the case with my others. Think the supercharged YS-91 will remain in the box till I figure all this out, since from what I read it can be one of the hardest to set up.

Hello,
I have finally maidened my Skybolt today. I got it up, trimmed and down in one peice but it wasn't fun. I could use some help as all my flying experence ( Ten Years) is with combat planes. ie: no rudder or landing gear. It has the Saito 125 with 14x7 3 blade. Plane weighs 10 lbs. I tached the engine at start and it peaked at 9k and I backed it off to 8600. Is this in the ballpark as far as rpm's with this prop? I let the plane run the whole length of the runway to gain airspeed and in my mind it didn't seem enough but I lifted off anyway and just about lost it. Wings were dipping left and right while the plane tried to gain airspeed. once in the air it was ok. The next issue was at landing. I had a slight crosswind maybe 5 mph. I banked to line up with the runway and it seemed the tail did'nt want to come around so I gave some left rudder and the plane rolled right. Did I input to much rudder so that caused the roll? Thanks for any help.

Rick

Rick,

I can visualize what is happening only from what you wrote.

I also do not wish comments that I think you are dumb as I am sure you are not dumb,

It appears that perhaps you have ailerons-rudder mixed and in the opposite direction.

The rudder should be (and I am not saying it is not) mixed to the ailrons and not the ailerons to the rudder. It is easy to confuse that in the transmitter setup.

The rudder mix should be in the same direction as the ailerons. Ailerons to roll left with a bit of mixed left rudder. I am trying to explain your application of left rudder resulting in a bank to the right. You did not say if the 5 mph crosswind was from the right or from the left.

See if you can remove the rudder mixby the flick ofa switch. I do not know which Tx you have.

Recheck all control surfaces prior to next flight in case the rudder servo was reversed accidntally while setting up the transmitter.

I also have a 14 x 7 three bladed prop ( it is a Master Airscrew ) powered by a Saito 125. A 9000 rpm peak is just about what I got on the tachometer. Back on the rich side to 8600 is ok .

I use presently about 30% exponential on all three surfaces. Most people have a tendency to overcontrol as I observed other fliers. Be quick but gentle on the controls.

Do not be surprised if someone posts to ridicule me. I am trying to help based on what information you supplied. If others have constructive advice, so much the better.

Take your time and double check everything.

Nothing is luck. All is proper settings of the model and of the transmitter and servo responses to inputs.

Best regards de Zor

Zor,
I wasn't using mixing but had planned to learn to use the rudder. Do you normally switch it on and off as needed or keep it on all the time? How much rudder do you program in to start. How does it haveing it on affect other maneuvers?
On take off, do you let the tail come up right away or keep it down with elevator?
After a nights sleep and time to think about it I might have kept the tail down to long which kept the plane from gaining airspeed. Also I set my cg on my fingertips. I'm thinking I might be balanced to far forward. Today I'm going to put together a cg sling so to be more acurate on setting it.
Thanks for the help, its taken as intended.
Your name is interesting, is it short for something longer?

Rick

I reassembled the motor and fired it back up again on Sunday. First full throttle had it kick off the prop again, so the lawn has another Heavy Hub buried in the grass somewhere. Found the lock nut and installed a new prop, (old one had a large knick at the root) and removed the fuel button. Engine ran perfectly, which suggests to me the buttons do not tolerate vibes. Ran another full tank through it, then tore it open again to check. Good lube in the case and no binding. I now strongly suspect the overheat was a lean condition from the button leaking air and aggravated by the airflow in the cowl.

I brought some thin glass sheets home last night and will try to pattern out something that will allow the cowl to curl around when fitting over the head.

p.s. Just feel lucky that prop flew off the other way and didn't poke a hole in the side of the new pool. Wife would NOT have been happy.

I would fly it again and try using the rudder during normal flight. As far as I can tell, from my experience and reports in this and other threads, rudder input causes the GP Skybolt to roll in the same direction as the input. I wonder if you didn't just catch a gust under your wing, because that's not the way the plane usually reacts to rudder input.

In fact, using rudder to make coordinated turns has a tendency to roll the plane causing the need for opposite aileron. This is the reason that people who have actually flown the GP Skybolt often mix in opposite aileron to the rudder. Rudder is master, aileron is slave. I forget the percent on my Futaba 7c, maybe -15% or so. This will let you use rudder in coordinated turns and help a lot with knife edge flight.