Zor

Scroll to posting #590. It will give you a good idea of what I did.

The landing gear can break away without disturbing the flying wires.
The top wing is removable just as if no flying wires were installed.
The bottom wing comes out by removng the two fuselage nylon screws.
The flying wires can stay on the bottom wing by removing only one screw on the cabane.

Of course the flyng wires are real to take most of the stress on the wings just like in the full size Skybolt.

Regards de Zor

Zor

Addressed to all interested in building and/or flying a Skybolt.

We need peripherals ___Accessories essential to our Skybolt healthy support.

Some are a battery to feed our electric starters.
Perhaps we use a power panel fed from a 12 volts battery.
Most power panel can also charge our glow plug heater cell.
We may run an electric fuel pump.

If you are experienced and know all about this stuff, you do not have to read any further.

Many use a power panel similar to the one illustrated below.
This one is a popular Hobbico Deluxe Power Panel II . Others of different appearance have similar electrical circuitry and similar functions.

I have taken this one apart and traced its electrical circuitry. If anyone has any interest I can help.

I am using a typical 7 Ah (ampere hour) battery and its acompanying charger.
On the charger it says Hangar 9, Model HAN103, Input 117V 60 Hz. Output DC 12 V 600 ma.
It is an inexpensive charger which is NOT constant voltage or constant current output.
The 600 ma rating is likely a maximum current that should not be exceeded.

In one picture it is charging the 7 Ah battery and I am reading the charging current. It reads 119 ma. and the charger is quite hot. It is not a charger designed to supply a constant current of 600 ma. A constant current charger needs a monitoring circuit so that when the battery reaches a specific voltage the charger switches off or switches to a trickle charging rate.

i am planning to buy a higher capacity battery and mounting my field box on wheels.
This battery does not have enough capacity. With larger engines the load to run an electric starter is often quite high like in the 30 to 60 amps. The 7 Ah does not go very far for the battery to drop in voltage and current debiting ability.

CAUTION: With this power panel the glow plug feeding circuit stops to operate below about 10 volts on the battery. So if you cannot start your engine while using the panel to feed the glow plug, have a look at the meter. You may find the glow plug current has dropped to nearly nothing and your engine does not fire. ( Do not ask me how I know that. That is one reason I took this panel apart and pulled out its cicuitry).

The three other pics show the voltage at the unloaded outputs ___
for the glow plug cell charging. 12.58 volts
for the glow plug feed 12.54 volts
and for the 7 Ah battery. 12.98 volts NOTE that the battery is under charging conditions and this voltage is the effective voltage feeding the other outputs. If the charger is disconnected and the 7 Ah battery drops to, let us say 12.0 volts then the other output would follow in proportion.

The output to feed the glow plug is marked 1.2 volt on the panel but it is not what we read. We are reading the max voltage of pulses which are ajustable in width (time) to feed the glow plug with the current measured by the meter as we use to potentiometer to set that current near 3 amperes.

I have not seen yet anyone flying a Skybolt on electric power.
I better mention that I am aware of other threads discussing batteries and chargers.
If you get lost or confused in those threads and you are flying a Skybolt then simply ask your questions here in the "clubhouse". You will get clarification.

Enjoy your flying with good electrical requirements as needed.

Zor

Zor

Hi Ho or Hi Hi,

I went to the flying field this morning but did not fly.
Half a dozxen guys were there and only oneflew one flight.
He landed in the trees at the downwind side of the field..

The wind was blowing 25 mph and gusting up to 40 or more mph.
A 20 year old model, well glued and the only damage was a broken prop and a 2" long tear on the left wing top side. That plastic sheeting has little resistance to puncture or tearings.

QUESTIONS ____
If you are using two servos for the ailerons; one in each wing ___are you using a Y connector ? or are you using a mixed transmitter channels ?

If you are mixing two channels, which ones are you using ? Which channel for the right servo and which one for the left servo ?

Has anyone used the "flaperon" set up ?

You do not have to be flying a Skybolt to respond.

Any reply is much appreciated. Thanks for responding.

Zor

Cougar429

My Feedback: (3)

I set up flaperons in the Eagle 2, running one servo to the standard input of Channel # 1 and the other to Channel #6. My Futaba 8UHPS also allows the option for that second servo to be flipped to Channel #5 to run with a 5 channel receiver. Sorry, just sold the plane so cannot remember which was which. I think the RH servo was Channel #1.

Mixing took a bit of time to have both ailerons move differentially and drop the same amounts when in FLAP mode. I assigned the flaps to one of the 3-position switches for FULL UP, MID and FULL DOWN. Also tied elevator into the MID and FULL DOWN to account for trim changes. This took a few flights to dial that in.

NOTE: One thing I noticed and queried Don Edberg about was the fact that full down only had the down wing servo lift when the stick was deflected more than half way. This is normal, so if full-flap mode any banking was attended to with rudder only. This now included another mixer to up the rudder ATV in full flap in case I forgot to flip the D/R switch.

Sandmann_AU

Two channels. Only reason for this is so I can use Aileron Differential, to reduce roll coupling. I also mix a bit of rudder into my ailerons too. If not for this I'd probably still use two channels, but only because a second servo extension is cheaper than a Y adapter and all my Rx's are 7 channel. Also, I use "lost model alarms" on all my birds, they connect to the aileron servo and they behave unpredictably when used with a Y adapter & two servos.

I'm using a Spektrum DX7, so my channels are "Aileron" for port and "Aux1" for starboard.

There's no way you'd need them on a 'bolt, or any other bipe really, as the twin wings provide lots of both lift and drag. I've used them on other (mono-wing) planes and I've always found them to be somewhere between useless and dangerous. The reasons for a plane to have proper flaps are taking off on short runways with a heavily loaded plane, or landing (or flying very slowly with) a plane with a high wing loading. Reason 1 is typically void with RC models as they don't carry loads and almost always have a much higher power:weight ratio than full size aircraft. Reason 2 applies to RC planes for models such as scale warbirds so they don't fall out of the sky/tip stall etc as you're landing them. Some people try to use flaps as air brakes to slow the aircraft but this only works at larger angles (greater than 45 degrees). At normal angles all they do is provide more lift. Using flaperons in this fashion reduces the functioning of the ailerons significantly, causing more problems than it fixes.

I do have a 46 sized Harmon Rocket 3 that I've fitted a 60 2 stroke into. Because of the extra weight, stubby wings, and the difficulty in getting the engine to spin slowly enough to let the plane slow down it really needed real flaps but came without them. On a landing approach it didn't want to stop flying, and would descend to about 3' above the runway and then just float the entire length, but if I slowed down earlier so it would land properly it got very unstable and wanted to tip stall. I ended up modifying the wings to have genuine flaps which completely changed the way it lands; I now start my approach at a higher altitude, chop the engine completely as soon as the approach begins and drop the flaps at the same time. She descends now on a roughly 45 degree flight path, and I just tweak the throttle before she touches down to reduce the descent rate and induce a little flare. Landing this plane used to be a struggle, now it's a thing of beauty.

Sandmann_AU

Just a quick update on my build. Fuselage is basically complete (at least up till the point where the instructions say to go build the wings). I've gone with the idea of a twin seat, open cockpit style. I'm using the pilot from my first 'Bolt and I got him a girlfriend to sit up front. Turns out that with the twin seat design it becomes obvious that my original pilot's about the right scale but an inch too short, so I had to carve & paint a balsa torso for him so he could see over the dashboard. I'll chop up the standard canopy to make a pair of windshields.

I've also used a dual elevator coupling made by MK. This is basically a carbon fibre rod that runs across the fuselage and pokes out either side just ahead of the horizontal stab, and has 3 control horns on it. This lets me use a single elevator servo & single pushrod without to make having a clumsy Y pushrod and having uneven elevator movement. I was going to use a carbon fibre pushrod too, but it weighed about the same as a steel one so I figured I wouldn't bother. I had to stick balsa "bumps" on either side of the fuselage where the rod exits so the mounts (with the tiny little bearing races) could be mounted parallel. If you try to force them to match the plane's taper it all seizes up and gets hard to move.

The rudder's using a Dubro 2-56 size pull-pull system, as do all my planes. No particular reason other than that I like them. I've also got a dubro tail wheel mounted to the plane, but I'm not convinced that I'll use it yet. If I change my mind I can just remove it and go with the standard one.

The engine's a Saito 1.25ci 4 stroke, mounted sideways. I'm using the standard muffler with a 90 degree adapter, which will let me hide the muffler inside the cowl with just the tip exiting through the bottom of the fuselage, plus a silicon exhaust extender to keep the filth off the bottom of the plane. Chances are I'll be using a MAS 3 blade 15x7 prop with it, unless it behaves poorly when spun up in the real world.

Cougar429

My Feedback: (3)

Love the girlfriend idea.

Would like some more info or pics on the CF rod idea. Sounds like an elegant solution, (and I love those) but I come up with some questions. From my own experience I found standard, linear-orientation CF rod is great for deflection loads, but torque is a different fish. The other question is if you run the servo linkage fully embedded in the fuse and, if so, how you access it? Same type of queston regarding installing the arms to the rod withoud damaging the fibers.

Sandmann_AU

Yah, she looks happy up front... big grin on her face. Let's see how happy she looks covered in dead bugs with no goggles.

OK, I'm not 100% sure this really is carbon fibre... maybe it's nylon etc. The horns themselves are definitely some sort of plastic. All I know is it's a man made material and it's light, strong, & black. I'll include a pic from a website of the device here.

Easy question first... regarding the pushrod being encased. Yes it is, but I've done things a bit backwards to normal using a Z bend on the elevator coupling and a nylon clevis on the servo. I figure the Z bend's the bit least likely to need any attention, and I can adjust things at the servo end. The website I found this on (dedicated to pattern planes) recommends ball joints and CF pushrods all round but I think that's probably overkill. The two external pushrods will be steel 4-40 size, with adjustable clevises on one end and soldered ones on the other (same idea as the aileron linkages). However no, once it's built (at least in the skybolt) accessing the internal bits would require surgery.

OK, I just wrote a huge paragraph trying to explain how it all works, then I realised it's easier with a diagram, so I'll attach one to here. The purple shows the main shaft that runs through the fuselage, and the central control horn that's fixed in position. The red is the wedge shaped balsa "packing" & supplied thin ply plates I had to use to give it parallel mounting surfaces. The green is the actual mounts that are held in place with two small machine screws and contain a ball bearing race, the blue are the two external control horns. What's not shown is a single bolt that goes through the entire thing from one external horn to the other to hold it together.

Fitting is a matter of locating a suitable point (it has about 1/4" of adjustment in its length so that's not too critical), drilling a pair of 12mm holes (take care to get them exactly perpendicular to the centre line of the fuse), fitting the two external mounts with their tiny machine screws, fitting the main shaft (has to be done from inside the fuse, not easy once the plane's already built!), sliding the two external horns onto either end of the shaft (the shaft has a pair of "flats" on either end so there's no slop in the horns, and they can only be fitted in line with, or 180 degrees from, the central horn), then screwing the long bolt through the whole contraption to pinch it together. I've found that I can remove one external horn & mount and the whole thing will stay in place as long as I leave the other side fitted, allowing me to sand, cover etc the plane without the device disappearing into the bowels of the plane. The external horns are quite a tight fit onto the shaft and won't easily pull off - in fact I've been using a large screwdriver to lever them off rather than just tugging at them, for fear of snapping balsa etc in the removal attempt.

Finally, the thing's made by a mob called MK, and you can see it [link=http://www.centralhobbies.com/control_linkage/bellcrnk.html]here[/link]. There's another one on this page by someone called CHS but it uses a sleeve rather than ball races and so would probably create more drag.

**EDIT** Hmm I just looked more closely at the CHS ones, they appear to have ball races in them too, so scratch that. FYI I didn't order from that site, my local hobby shop managed to get it in. I have no idea what that site's service is like.

Cougar429

My Feedback: (3)

Now you have the pic up that suspiciously looks like the collective pitch rig on my students nitro heli. Will have to have a closer boo at it next time I'm over.

EJWash1

My Feedback: (3)

Sandmann,

I’m using the CHS elevator bell crank on a vintage Sig Komet pattern ship (for classic pattern ship competition). Of course I didn’t find this linkage option until after I assembled the fuselage (DOH!). I performed the required “surgery� and reinforcement.

In this case of the Komet, following the plans would have meant that the elevator and rudder pushrods would have been fighting each other for travel room as they both exit at the squared-off end of the fuselage. The CHS bell crank eliminates this problem. Like you said, it has to be mounted perpendicular to the fuselage for/aft centerline otherwise the mounting flanges pinch-in and causes binding to the rotating control horn shaft. I’m using basswood wedges as a mounting platform.

I’ve ordered from Central Hobbies at least a half-dozen times over the last couple of years. I’ve never had a problem and they shipped my orders pretty quickly. They are geared towards the pattern flying community, but there’s no reason that their “bits-and-pieces� can’t be used on any plane. More $$$, but worth the quality.

http://www.centralhobbies.com/

EJWash

Zor

Greetings to all,

Saturday (25th) was a very windy day and some fellows were at the airfield but no one was flying.
The wind was blowing 30 plus mph and gusting up to 50 mph.

Yesterday the wx cooperated and the Skybolt had a good time flying.

The trim to ailerons needed wassix clicks to the right of 26 for full trim. That was not bad.
That trim was at half throttle (cruise power).

The trim to rudder was two clcks to the right of 26 for full trim. Again not bad.

The trim for elevator was 15 up elevator of 26 of full trim.
That trimming was done at the beginning of the flight with the fuel tank nearly full and located ahead of the CG. It shows the CG is a bit too far toward the nose.

A new balance will be done. I have 4 ounces of lead in the cowling and that will be reduced to move the CG about 1/8" back. Next flight will show the results and any need for further adjustment.

Did not run out of fuel this time and had a perfect beautiful greased on landing on the runway.

No I am not the guy enjoying multiple flights initially. I want this plane to be as well balanced as possible so some linkage adjustments will be done for the ailerons and the rudder.

Moving the CG back 1/8" will show me how many clicks are needed (if any) on the next flight.
The trim on the transmitter is digital and a subtrim can set the zero of the servos. I may experiment with this subtrim. but first I favor the mechanical adjustments so that both trim and subtrim can be at zero.

I wish all can share the fun I am having. Surprised that someone can be in this hobby for such a long time ?

I regret I do not have a video camera and I would not be able to show movies anyway as I am not using third party servers. That is a subject I do not wish to discuss. I will try to get someone to take picures in the airnext time. I posted one airborne picture before but the plane was at altitude and too small.

There is always anoher day. Hey this is a hobby; there is no rush.

Wishing all the fun I am having.

Zor

P.S.: added by editing 27 Sept 2010 at 23:20 EDST
I asked gently the fellow in front of the airplane to kindly move behind the prop.
The legs seen are not mine. I was behind the prop as soon as the engine fired.
I was in front of the prop only to start the engine and take one picture.

Sandmann_AU

Hey guys...

Just had a thought while admiring my latest handiwork. When I cut out the engine cowl I took the absolute least off the end so it's longer than normal. I also haven't sanded back the nose of the fuselage so the cowl fits on properly yet. I measure the engine & mount, and compared it to the firewall to end of cowl and I need to move the cowl back about an inch to get it over the engine. It then occurred to me that maybe I could put a couple of the blocks that're intended for mounting a 2 stroke under the engine mount and move the Saito forward an inch or so, thereby reducing the amount of nose weight I'll need.

So what do you think? Will this substantially alter the geometry of the plane? Will it change things like the appropriate CG etc? Or can I do this and end up using less lead just by having a longer nose?

brenthampton79

Just a thought for you guys using the chs elevator bellcrank, you can use two hobbico cs-110 mini servo's in place of one standard servo if you would rather have dual elevator servo's and the two mini's have more torque and less weight than the one standard, thew mini's weight .6 ounces a piece and a standard futaba weighs in at 1.3 ounces. Just thought I would throw that out there for you guys I am currently using two mini servo's for a 40 size gp extra for dual aileron servo's with no issues and they work great instead of the single servo set up that the directions show. Like I said just a thought I would throw out there, I am planning on rebuilding my skybolt this winter and I plan to go this route on the elevator, and the ailerons using the cs-115 for the ailerons for the higher torque and to help keep the plane light as well

Sandmann_AU

Yeah but that either puts two minis in the rear, which is equal to 3 times as much weight at the front, or has you requiring two pushrods (extra weight), and two channels & mixing or a Y adapter. Added complexity either way really... both have advantages.

brenthampton79

true sandman I just thought I would throw it out there for people that haven't thought about that option it definately depends on if the plane builds tail heavy or nose heavy

Zor

Hi everyone,

A few comments relating to some statements read in this thread.
I will not type in the original statements but most comments below are quite easily related for anyone who has followed the thread.

Each paragraph below is one topic with possible explanations as necessary ___and are my feelings.

Weight ___It seems to me useless tomake any effortsabout saving some weight in this model. Remarks about saving a few grams here or there boil down to the fact by coparison that the ARF Skybolt is reported to weigh about 7.5 pounds while any buil kit (Great Plains) end up more like 10 to 12 lbs.
One pound is 452.8 grams and it is not possible to detect any flying difference betwee a 10 lbs and a 11 lbs Skybolt. Only 5% morre speed is needed for the plane that weigh one lbs more. I defy anyone to really judge a difference in flight behavior.

ARF versus Kit built ___There is an appreciable difference in final weight between those two. Obviously the ARFhas to be somewhat differentin its structure and is likely more delicate. I believe it is aimed at using an engine size around .61 to .90 . Most kits end up with an engine size more like 1.00 to 1.50 and even larger. One can play around with "which engine prop cobination can generate a thrust of X many lbs. X here can be the weight of the model or even more.

Flight conditons ___It is recognized that a heavier machine has "so called" wind penetration. Wehave to remember that wind penetration is mainly a matter of wing loading and not the size of the airplane. Think of a model having 12 feet wingpan ( 144 inches ) that is made so light as to weigh 2 or 3 lbs like all light foam, no covering, tiny servos, a mini brushless motor and a 1,000 mah battery. How would this fly in a 15 mph wind gusting to 20 mph. The Skybolt at 11 lbs just has a laugh at the wind..
if you like a slow flying machine that seem to fly backward in a gentle breeze, you are out of luck with a Skybolt.

Crash results ___I do not have any bad or wrong feelings about ARFs (factory built models) but I find it difficult to forget the comment of a fellow a while ago who wrote " I do not know why my model crashed. It just came down in a high speed spiral and met mother earth. When I got to it, there wa no structure left. It appeared the model was originally held together by its skin. Hundreds of small balsa pieces" Manufacturers cannot afford to pay workers waiting for glue to harden or for paint tocure.

Cost ___LHS (Local Hobby Store) are very handy to be around and particularly if they are closed like less than 20 miles (better around the corner LOL). The majority of modelers are not rich people. Go to your LHS and buy one quart of clear nitrate dope, one quart of clear butyrate, one quart of white, a pint of red, a pint of blue and one quart of thinner and you get diluted dope for $152.00 . Now go to the supplier to the full size plane refinishers and buy genuine non diluted dope exactly the same quantities and walk out with a $55.00 bill. The diluted dope from the LHS need9 coats to fill the fabric threads, You do it with 3 coats with the genuine dope. Cost ratio to finish your model is nine times cheaper not considering considerably less work.

More on cost ___Buy a couple of specialized ironing irons and finsih material. at $2.60 a foot or $7.80 a yard about 30 inches wide. or buy polyester 45 inches wide at $4.95 a yard and dope it.
You will never see a winkle and the finish will not tear in a crash. The weight difference if any is negligeable as you fly the model. One thing about dope; it smells better than Channel 5.

Construction tips ___Do anything that you enjoy doing and do it the way you like. If you do not know how to do something ask questions but write your questions in a clear precice non ambigous manner so that people will respond. Do not let the helper have to guess what you are doing or trying to do.
If your queston is not clear, a response based on guesses will be the same, jus a guess that will not help you. Be cautius of opinions that are not backed up wih reasons or experience.

Enjoy what you are doing and how you do it.

Zor

Cougar429

My Feedback: (3)

Loved the smell of dope years ago. Only thing was then I had my own shop with lots more room to work, air, etc. Only problem I found was the solvents used to destroy the nice structural blueprints I had hanging in my office there. My friend had a blueprint company and when maintenance to their machines was done every month the techie would bring his own test material. Had cutaways of the L1011, Shuttle, etc. Came in one morning to find blank sheets???????????????????

Today I have taken over the downstairs family room. Don't think we'd be able to tolerate that routine now.

Here's an example of the Covering and dope method:

Zor

Hello "Skybolt Hangar and Clubhouse" viewers,

Well ___it is a different introduction.

This morning it is reported that 27,229 viewers have visited this thread. Of course many have been visiting many times including those who haveto date posted662 posts.

Thanks to "biplanemurphy" who initiated this thread to share in particular our love and tribulations of Skybolt lovers.

While this thread focuses on Skybolts it has appeared to me that it is also a "clubhouse" as its name implies and I have felt free to discuss sideline topics hopefully beneficial to us. Of course we also have other models and I presume it is acceptable to discuss and share topics that treat generally applicable methods of building, assembling, setting up, and general handling of our model airplanes.

I like to share ideas, methods of doing something ___sometime it might not be the preference or the best but I post only things that have been proven to work and give good results. We all have our preferred way of getting the job done. Often it is affected by our spare hobby money and I belong to that group.I count every penny I spend on this hobby and have been doing it for many years.

Along that line of thinking I have often built my own tooling. Years ago I did not have the money to buy a table saw so I built one out of scrapped plywood, an old 1 HP motor and a ball bearingarbor to hold the 10" dia blade. The table top (plywood) could tilt to 45 degrees. I now am fortunate to have a manufactured one and a small vertical drill. I also have a shaft on an old GE 1/4 HP motor from an old washing machine and this shaft can hold a grinding wheel or a buffing wheell to polish things. So I can sharpen knives, chisels and whatever a grinding wheel can help.

Hobby wise, I do not have a sofisticated shop. I do my building of models in the dining room. I even do my doping in the dining room. I open the dinig room window and place a 16" fan to draw (blow) the air outdoor so fresh air from the rest of the house is constantly drawn to the dining room (other windows are open so fresh air is coming in from the kitchen and living room.

You may complain that you live in an apartment. I could do the same in an apartment. When there is a will there is a way. You say your wife would object ? Change the 40 for two 20s Hee Hee !!!

So I do not have many commercially made tools for the hobby. I do not need plastic shrinking irons because I finish my models with fabric and genuine aircraf dope as the best covering and finish (like full size older airplanes). Two high quality brushes; one 1/4" wide and the other 1/2" wide. Total cost $7.50 years ago and they still do the job.

I made my own propeller balancer.

I can weigh things down to 1/2 oz with an old postal scale; a very rare requirement. I can weigh my models with an old bathroom scale. Since I do not build models for indoor 3D flying, I do not care if my models are 10 grams heavier or 1 or 2 pounds heavier depending on model size of course. I have models that are from 17" to 72" wingspans. From 8 oz to 11 lbs.

One of my most expensve tools came from three cardboard, 8 1/2 x 11 inches from the back of writing pads. One has a corner cut off and is my tail feathers guide to make sure the fin and stabare 90 degrees to eahc other (no dihedral on tail surfaces). The two other cardboards are partly cut away on one of the long edge and can sit on top of the main wings and gives me an accurate indicaton of any warp or a good evaluation of washin or washout. I really broke the bank on this tool as you can imagine. You stand at the end of the wings and see if the upper edge of the two cardboards are parallel to each other. It is a bit like looking at a picture hanging on the wall and judge if it its edges are horizontal and vertical. Ya ___ I know your frame happens to be an oval but you can still judge if its two axis are horiz and vert. Ha Ha . . . you did not catch me offguard.

I have a small level with three separate bubbles that center at horizontal, vertical or 45 degrees. Cost was free as a piece of advertising. It is 9 inches long. The bubbles are 1/2" long and black lines are also 1/2" apart.
It just happens that the bubble moving its own length gives dead on 1 (one) degree from the horizontal.
It is being converted into an incidence meter which will have a 1/2" scale per degree. It is easy to interpolate a half inch into 1/10 th of a degree. I have not seen any commercial incidence meter with the ability to read that accurately. Yes you can call me "crazy" but that is what crazy people do.

OK stop reading before you get a headake ___LOL.

Have a great day , , , ,

Zor

10:00 AM , breakfast time.

Zor

Hello everyone,

Going to the flying field this morning to fly the Skybolt.

The control surfaces linkages have been readjusted toward the aim of having zero trim and zero subtrim in straight and level flight at half throttle. Half throttle on the transmitter stick does not mean anything like half thrust. It only mean the carb is rotated to the half way point of its rotation. Since we have two circles in the carb we do not have half the cross section of the venturi opened. We also do not (at least I do not) know the relationship of carb opening versus the actual thrust existing that is pulling the model against the air resistance.

Basically I am aiming at a cruise speed about half way between stall speed and maximum speed. Max speed obviously when the carb is fully opened andthe mixture is best for the prop in use and resulting rpm. In this case a three blades Master Airscrrew 15" dia by 7" pitch (per manufacturer of the prop).

The flight(s) today will give a clue to further touch up.

The spinner breaking problem may have been solved as I found a 2 1/2" dia aluminum spinner at a more reasonable price than $64.00 (plus 13% Harmonized tax). This one cost me $36.00 including tax.
The back plate is on the Skybolt but the cone is not. I still have to enlarge the three openings for the blades.

Zor has graduated to the 2.4 Giga band for the next ship. Skybolt still flying on the XP7202. (72 Mhz band). I bought a DX7 kit which includes transmitter, dual receiver (two antennas set up for diversity) 4 DS821 digital servos and all mounting hardware, Tx and Rx batteries, charger, wiring harness, manual.

Ican tell you that the manual for the DX7 is written in much improved English compared to the manual for the XP7202. The comparison is easy since the feature selections is nearly identical. The main difference has to do with the RF (Radio Frequency) band in use and the "binding" (receiver to transmitter) needed for the 2.4 Ghz band.

I will also, soon, be sailing.

No not in a boat but in a sailplane. Since we cannot rely on thermals or any updrafts worth talking about at our field, this saiplane has a motor for climbing.

Of course, Zor being Zor, it had to be a kit so I can glue it properly and make some changes (modifications) as I wish. A few mods are already in my mind. I found it interesting that the designer of this sailpalne is the same fellow that designed the Skybolt.

More later as I have to get to the flying field.

Enjoy your day,

Zor

P.S.: Edited upon reading to correct some spelling.

Zor

Hi ! ___

No flying yesteday because it was drizzling at the flield.

Went to the field again this morning and the wind was blowing 20 mph and gusting to 30 mph.
These are not suitable conditions to study the trimming and stability of a model.
That is of course if you wish your model to be well balanced on neutral trims at zero and subtrims also at zero.

Planning for this is now for next weekend (thanksgiving , 3 days).

I still wonder how a kit manufacturer can include in the kit a motor drawing 20 to 30 amperes and presolder in series wih that motor two switches.
One rated at5 amps 120 volts or 2 amps 250 volts, Toggle switch for the fuselage side.
The other at 3 amps 250 AC volts. Switch to be operated by a servo to turn prop ON or OFF.

Any comments from anyone ???

It seems to me illogical and I am tempted to open the switch and have an inside look.

Well I did. See attached pictures.
Everything seem rugged enough to carry up to 30 amps except for the little blade that switches the contact. I guess it become a matter of how long will this switch last carrying the high current.
Similar thoughts about thetiny toggle switch.

A picture of the Skybolt with its new aluminum spinner. I am hoping this spinner will not explode on me like the plastic ones did (two of them).

Pictures of the new kit that I will build myself. What has this to do with the Skybolt Hangar you might say? It has nothing to do with Skybolt but it is, I think and hope, part of the "clubhouse" where Skybolt owners an fliers exchange their thoughts and friendship.

This Spectra sailplane will be built the old fashioned way like the Skybolt was.
I am looking forward for the perfume of aliphatic glue and aircraft dope.
I am missing that .

I am inviting newcomers and anyone to post and let me know if they would like a log thread on its construcion.
If you would like, then place a posting here (in this thread) and let me know. If enough are interested, I would open a thread separately to cover the postings ot its progress with lots of pictures.

With best regards to all,

Zor

Zor

Since no response has been received, I will not open a thread for the construction of my Spectra sailplane.

I do realize that there is already so many "build log" threads to look at .

Zor

Zor

Hi everyone,

I went to the flying field this morning and played with the Skybolt.

No poblems starting the Saito 125 but the first three starts the engine was running backward.

I wish to understand how a four stroke can run in the opposite direction.
It did run for an apprreciable time in each case like 20 second to half a minute till I shut it down.
That sure is a fascinating subject to try to figure out.

If anyone can explain it sure would be appreciated.

I did a lot of ground taxying at different speed.and observedthe ground steering behavior.
It steers very well but it also showed me how roughthe runway really is.
Most do not care about the runway condition since they nearly all have more thrust available then the weight of their model. They do not need a take off run. Full power and some up elevator and they are airborne in one or two seconds.

The engine was responding nicely but I did not use fullpower; not even half throttle on the Xmtr stick.

On one of the fast run full power was reached and the plane took off and started a climb nosing up about30 degrees and at about the height of a single story bungalow (20 to 30 feet) the engine quit..

She nosed down and quickly hit the ground with a nose down attitude of about 30 or 40 degrees and the right wing hit first. The right wheel took most of he impact and the wheel pant cracked at the joint .

These pants are made of two halfs glued together and the original halfs were not the same length (3/16" difference) and he rear part of that joint was weak.

The inside of the pants will be fiberglassed as a repair. Both will br done although the left pant has no damage.

So I am finding out the weak points. It is nice to see the plane falling out from that height and that weel pant is the only damage.

I have a strong suspicion why the engine quit and I will look into that.
The high speed mixture needle was opend only 2 1/2 turns and I think she leaned out.

I saw three fellows taking their model home as a basket case. I felt sad about that.

Zor

Sandmann_AU

Only a guess here... I'm assuming there's a little overlap on the cam lobes... ie: the inlet valve and exhaust valves open slightly before Top Dead Centre (TDC), with the compression & power strokes swapping functions. With the engine spinning backwards that would let it suck a little fuel at the beginning of the reversed exhaust stroke, and exhaust slightly at the beginning of the reversed compression stroke, thus allowing it to idle (roughly) backwards but without enough fuel or exhaust to do anything more than an idle. It could also be explained if the camshaft timing were retarded (eg: the cam is on or more teeth "out" from where it should be). If that were the case it would also run backwards, and have less than optimum power when running forwards. It can't happen in a car's engine (unless it's already hot & has significant carbon build up) because the spark plugs wouldn't be firing at the appropriate time, but of course in a glow engine the the glow plug's always hot when starting so ignition isn't controlled.

I'd agree, that does sound like a lean condition, or possibly overheating (or both) - unlikely in your case since you have most of the cylinder poking out in the fresh air. You might also want to check fuel flow, pinched fuel lines etc, and make sure the tank's vent line to the muffler doesn't have a hole allowing tank pressure to escape. Get an assistant to hold the plane horizontal while you wind it up to full throttle, then have your assistant hold the plane vertical (still with wide open throttle) for a minute or more, to see what happens to the engine speed. IF the engine speed remains constant or even increases slightly you have plenty of fuel flow and your mixture's probably about right, if it falters and/or dies then you have either restricted fuel flow or a lean mixture. You also want to check the cam timing as I mentioned re: the engine running backwards.

Yah, it's a tough model, even for a kit build (which are always stronger than ARF's). That's the positive side of it being a heavy model, it's fairly forgiving of abuse.

My build is basically complete now, I just have things like the final sanding, trimming the angles on the control surface leading edges, hinging the ailerons etc still to do, then the covering of course. I've decided on I've cut the cowl to suit the engine & exhaust already - I ended up mounting it horizontally and used a 90 degree adapter to get the muffler mounted inside the cowl, with just the exhaust pipe sticking out the bottom of the cowl back toward the firewall. I'll have to get a small length of aluminium tube to extend the exhaust pipe, make it look like one of the "stingers" on a pitts muffler to keep the mess off the bottom of the fuselage. Not much of the engine sticks out the side of the cowl, only about 1/2 of the head at the front and the valve covers. I'll include a couple of pics.

I tried a couple of props on my Saito 125, a 15x8 2 blade, and a 15x7 3 blade. I was getting about 8850RPM with the 2 blade but only about 8200RPM with the 3 blade. I put those figures into ThrustHP and it tells me that both speed AND thrust are better with the 2 blade... figures are as follows:

2 Blade:
RPM: 8850
Speed 67.05 MPH
Load: 405000
HP: 2.005
Static Thrust: 11.22lb

3 Blade:
RPM: 8200
Speed: 54.36 MPH
Load: 531562.5
HP: 2.09
Static Thrust: 9.63lb

As you can see I'm (theoretically at least) better off with the 2 blade prop in this case. I checked out the 14x7 and 14x9 3 blade props also but got similar results. Anything smaller (eg: 13x8 3 blade) will let the engine over-spin and won't have enough diameter to direct airflow around the fuselage well. I was using the fuel I had mixed up for my other (ASP 1.20 and OS 1.60) 4 strokes, so I will have to mix some up specially for the Saito, see if bumping up the nitro and removing the castor oil will improve the running.

Oh well, I'm going overseas for a 2 week holiday tomorrow, so all this will have to wait till I get back. Looking forward to seeing it airborne.

Cougar429

My Feedback: (3)

If you stay with the same diameter 3-blade, the pitch has to be reduced to allow the engine to compensate for the extra drag.

I never had a lot of luck running 3-blades on my 2-strokes, but the Saito does not seem to mind.

Zor, good to know the plane survived. Sounds like you had the classic low-altitude, high-alpha stall condition when the engine quit. Usually ends up with nose down and one wing low. In real aircraft that takeoff zone is the most critical, since it would only allow for a straight ahead landing and dropping the nose IMMEDIATELY the power cutts off.

Had a few flights in the last week, including a couple on Saturday when we had a sort of gathering at the field. Was a bit on the windy side and I kept my maneuvers a bit tamer than normal due to that, (no "Money Shots"!). Also noticed it has been acting a bit strange lately. Think the elevator servo is on the way out and plan to change that before getting it airborne again. Skis also arrived, so better look at getting something else ready to allow the Bolt to shed its skin this winter.

On that note, wanted to ask if anyone has skeletonized the sheeting and/or tail on the Sig offering to reduce the weight aft of the CofG.

Sandmann_AU

Yah... the 2 blade's a 15x8 and the 3 blade's a 15x7. There's no 15" 3 blade with a lower pitch available. I did run a 3 blade on the OS1.60 twin cylinder with my previous Skybolt, but that was more about ground clearance than anything else. Think I have a 14xSomething 3 blade prop around the place, if I can find it I'll give that a go too. With the Saito I wanted to run a 3 blade for the scale look, but I'll happily sacrifice that for performance.

I will try flying all these props of course... you can do all the math you like, but nothing will tell you which prop "feels right" better than "the seat of your pants". I am expecting the best results from the 2 blade 15x8 though.