Author Topic: PIG UPDATE NEW MOTOR (Read 5597 times)

Greg L Bahrman · « **on:** July 04, 2006, 12:36:36 PM »

Man, what a waste of time. Could be the scale but I doubt it. It was bought at a garage sale for $5.00 dollars so it would be easy to place the blame on it.
1. Hollowed all the top blocks
2. Bought 1/16 in. contest grade 4 lbs. balsa for sheeting the wings
3. Sheeted the fuse bottom with 1/8. The plans showed 1/4 in.
4. Sheeted the turtle deck with 3/32, not the recommended 1/8 and 1/4
5. lightening holes in the Stab and Rudder
6. Built up the elevators
7. The flaps are not even done yet.
8. Hollowed the wing tips
9. Hollowed the block between the stab and rudder fin.
10 lightening holes in the wing spar.
11. Triple cored foam wing
12. Hollowed the cowl block
13. Motor mounts are drilled with lightening holes behind the first former all the way back.

I suspect had I not done all that work it would weigh 100 lbs.

Sitting on the scale it reads 3 3/4 pounds thats 60 oz. with the ST 51 and no paint or flaps, but before we go any further I'll get another scale. But if it's more bad news my options are:
1. Stick with the ST 51
2. Go with a Saito 56
3. Go with a OS 52 4 stroke
4. The ST 60 is to wide and I would have to cut the mounting lugs to make it fit.
5. I guess I could buy a Hi-Tech PA 61 side exhaust but then I
would have to get rid of the 5 1/2 oz. tank.
6. With the 4 strokes I could go with a smaller tank
7. Last option. Have a nice 4th of July bon-fire!!!!

To say I'm upset is putting it mildly

Lee Thiel · « **Reply #1 on:** July 04, 2006, 01:04:44 PM »

One more option, send it to me?

I had one I called Porky, but it flew and handled well until a clevic opened!!! DORK

Bill Little · « **Reply #2 on:** July 04, 2006, 01:16:17 PM »

Hi Greg,

That sounds awfully high for the work you have done. I would check out a new scale!

What did you apply the CF with? and is there anymore sanding you can do??

I flew an SV 11 with a ST G51 that was at least 64 oz. It had absolutely no problems flying in all conditions. Now I would probably put a *bigger* engine in one, but that combo was good for 500 point patterns even in the wind at Norfolk (which was NASTY!).

My son helped it's eventual demise when he was moving up from beginner to Intermediate. But the Wing and Stab live on!

Bill <><

RC Storick · « **Reply #3 on:** July 04, 2006, 03:22:11 PM »

You have failed to mention what type glue and how many ounces and how it was applied to the wing? This is where fomie's usually gain their weight.

Greg L Bahrman · « **Reply #4 on:** July 04, 2006, 03:30:22 PM »

Wing Skins are put on the standard way, I think? Smeared epoxy on the foam core and scraped off with a piece of 1/16th ply a little larger than a credit card and returned to cradles to cure with weights. There was no excess epoxy anywhere. But you are right as I always felt that the wings felt a little heavier than they should have been, of course this is my first foam job, I'm used to built up wings

Larry Cunningham · « **Reply #5 on:** July 04, 2006, 04:07:43 PM »

Fly it! SV11s work well over a large range of weights..

ST .51 has plenty of power for it.

L.

"The one serious conviction that a man should
have is that nothing is to be taken too seriously." -Nicholas Murray Butler

frank carlisle · « **Reply #6 on:** July 04, 2006, 04:41:23 PM »

Greg,

Continue the build. Probably the plane is going to fly very well.

Haven'y you read any of the posts on the net? Some guys are building planes that weigh much more than what you have there.

Ron King · « **Reply #7 on:** July 04, 2006, 06:05:02 PM »

Greg,

I would try a better scale. I used a similar scale for twenty years and finally bought a decent digital unit. That's when I learned my planes were not as heavy as I thought.

The SV-11 can easily carry 64 - 66 ounces (probably more). The ST 51 is not the greatest choice, but can fly the plane okay.

Final thought for the day: Guys lie about the weight of their planes all the time.

I'm not admitting anything, but I think we tend to subtract a few ounces here and there when we are talking to each other. Kind of like women and dress sizes. One of my buddies told me he thought his plane weighed 60 ounces - I almost got a hernia lifting it. Sixty ounces my @$$.

Take care,

Ron

Jim Oliver · « **Reply #8 on:** July 04, 2006, 06:06:02 PM »

Greg,

Press on!!

One of my Tutors, with ST G51 weighs about 52 oz.
The other one, with the MVVS 51, heavy Rustoleum paint on the fuse, nose doublers and thicker stab (not to mention 1.5 oz. of nose weight) weighs 63 oz.

The only real difference I can tell is that the heavier one pulls a little harder, glides smoother and is easier to land.

Jim Oliver

Randy Powell · « **Reply #9 on:** July 05, 2006, 02:07:29 PM »

Greg,

Just go light on the paint or use iron on plastic. If you can keep the weight under 68oz or so, it will fly decently. I'd use light sheet balsa for the flaps. Perhaps rib them out. The SV-11 has a pretty thick wing and big flaps. It's a weight carrying capacity issue more than just the static weight. My new plane is about that (68oz) and is an awful pig in the air. Not because of the static weight, but because the wing just isn't designed to carry it. The thin and relatively sharp airfoil just can't take the weight. So It's going on a diet.

The new plane I'm working on is 626 square inches and the airframe ready to finish (as of yesterday) is about 24oz. Figuring 14oz for the drive train (engine, header, pipe, tank, prop and spinner - yes, I've weighed them all) will give me a 38oz pre-finish weight. I think I can keep the finish down to 12oz for an all up weight, ready to fly, of 50oz. That should be a killer.

Greg L Bahrman · « **Reply #10 on:** July 05, 2006, 02:19:09 PM »

I am mentioning this because several of you have mis-taken this plane for a SV-11 which it is not!!.....It is a Sig Magnum with a redesigned rudder. I think Bill mentioned he had a 64 oz. SV-11
Thanks for all your support. I'm still undecided about which direction to go. Still haven't got over the shock of building something that is heavier than a wheelbarrel.

Mike Clark · « **Reply #11 on:** July 05, 2006, 02:38:21 PM »

Hi Guys,

WOW Greg, I like the Magnum wing Greg. Definitly NOT STOCK! Having built several Sig Magnums and knowing what you are going through, I must ask what did your wing weigh before you slide it into the airplane? 13 or 14 ounces I would guess? Which is about 5 to 7 ounces more than a built up balsa wing.

Press on, Colors & finish should add another 4.5 ounces to the airframe which is a tollerable. 60-65 ounces is within good flying weight for this ship. Heck my first offering weigh in at 70 ounces, Ouch! And I thought I did a good job of building & Finishing.

My T&L ST51 pulled it like it was a 40 ounce ship with out any problems! 12/5 Zinger 5/22 fuel on 63' lines NO problems, well except on landing, I thought it would never land. Two complete laps while the power was off was not un common.

I got mine bolted up and will weigh her tonight, I'll post the weight.

Mike Clark

Bill Little · « **Reply #12 on:** July 05, 2006, 02:48:04 PM »

I agree with Mike, go ahead and finish her up! You just might be pleasantly surprised.

Bill <><

Mike Clark · « **Reply #13 on:** July 05, 2006, 08:36:11 PM »

Hi Greg,
Yep it is as I thought. The out of the box Sig wing will weigh about 15.6 Ounces and that is well fitted and a heavy dose of carving and sanding. I pulled an Old Mag wing from the pile and that is what it weighed. On the other hand a Mag Plus wing at 8.5 ounces seems paltry.

The Mag Plus outfitted just like your Magnum weighs in a 45.8 ounces That will leave me say 4 ounces of veil and 5 or 6 to finish with a finish projected weight at 55 to 57 ounces. The Mag Plus also has more wing and side area than the Stock version.

As i said finish her! This airplane will surprise you.

Mike Clark

frank carlisle · « **Reply #14 on:** July 06, 2006, 03:51:06 AM »

There are only two destinies for a model airplane. Hanging on a wall somewhere or in a trashbin. Everytime I build a model I understand that it may not fly well or worse yet it may crash. In either case I complete the build and each finished plane yields a little more experience and skill to use in the next build.

Greg L Bahrman · « **Reply #15 on:** July 06, 2006, 01:04:19 PM »

Quote from: Mike Clark on July 05, 2006, 08:36:11 PM

Hi Greg,
The Mag Plus outfitted just like your Magnum weighs in a 45.8 ounces That will leave me say 4 ounces of veil and 5 or 6 to finish with a finish projected weight at 55 to 57 ounces. The Mag Plus also has more wing and side area than the Stock version.

Mike Clark

Sure go ahead rub it in Mike, your making me sick!!!....Grins

Greg L Bahrman · « **Reply #16 on:** July 06, 2006, 01:07:57 PM »

Quote from: frank carlisle on July 06, 2006, 03:51:06 AM

There are only two destinies for a model airplane. Hanging on a wall somewhere or in a trashbin. Everytime I build a model I understand that it may not fly well or worse yet it may crash. In either case I complete the build and each finished plane yields a little more experience and skill to use in the next build.

Frank,
Or on the end of my lines on it's way to a 500 plus score!!!
As far as experience: foam is white, foam is HEAVY no more!!!...Grins

frank carlisle · « **Reply #17 on:** July 06, 2006, 03:36:26 PM »

On the end of the lines on it's way to a 500 plus point score is music to my ears. That's a real possibility.
Post pics of the finished model Greg, then a flight report.

And OH YEAH!!! No more stinkin' foam.

Randy Cuberly · « **Reply #18 on:** July 06, 2006, 06:12:10 PM »

Greg,
The plane looks great. Based on what you've said and what I see I have to believe that there is something seriously wrong with your "Bargin" scale.
I would come closer to believing 50 oz at this point than 60.

I have built and flown two "Magnums" in the past and one weighed 71 oz. Yeah I know that is a pig! It got heavy because I got in a hurry and wouldn't wait for a shipment of "good wood", and used balsa sheeting on the wing that could have doubled as flooring for my shop. However it actually flew very well with an ST60 in all but the very worst conditions.

The other one was configured to look like a big Nobler and called the 92 Nobler. It weighed 64 oz with a ST 51 and flew very well. Placed in a lot of local contests and actually won one or two. Probably flew a lot better than me... Later turned it into a test bed for several engines, most of which didn't work out, and didn't compare favorably to the 51.

I believe the Magnum to be a very good basic design and a credit to Mike Pratt it's designer. It will carry quite a bit of weight.

So unless, of course, you'd like to box it up and send it to me...finish it up and fly it, I think you'll be pleasantly surprised.

Randy C.

Randy Powell · « **Reply #19 on:** July 06, 2006, 06:41:21 PM »

Randy,

I think your point is well taken. I flew a high aspect ratio plane a few years ago. Very thick wing with a blunt LE and about 7.8 to 1 AR on 660 square inches (68 inch wing span). The plane actually came out pretty light at right on 62oz, but I had decided to use a Saito 56 fairly late in the process and didn't account for the rather longish nose. In the end I had to add most of 7oz to the tail to get it to balance correctly and that was with a pretty far aft CG. That along with the 1.25 oz of tip weight added put the sucker at near 70oz. And it flew great. Never noticed the weight, but then, the wing was able to carry quite a lot of payload and was just efficient as heck.

My new plane is based on a slightly enlarged USA-1 wing. At 68oz, it a pig and flies like it's dragging a trailer. The wing just isn't designed to carry this sort of weight. Opposite problem this time. It was pretty grossly tail heavy and I added most of 6oz to the nose to get it to balance and it's still suffers from touchiness due to too far aft a CG (for this plane). It will go under the knife this weekend to start finding ways to lighten the tail.

john e. holliday · « **Reply #20 on:** July 06, 2006, 08:43:41 PM »

Let me make it unanimous. As has been stated, finish the plane with paint. Forget the Mono. The Magnum is a big plane and it amazes me that enyone can get it to less than 60 ounces. Here in the land of Oz the heavier planes will punch thru the wind better. So show us the finished plane and let us know how well it flies. DOC Holliday

Greg L Bahrman · « **Reply #21 on:** July 07, 2006, 07:43:58 PM »

Hi All,
First I want to thank you all for responding in such a positive way. I will continue until Porky the Pig is done and in the air. Since I started this project I've heard all the stories about the fuse broken off behind the wing, wings folding in flight, stab folding in flight etc. etc. I have learned a lots of stuff on this project and probably will learn more as I progress to the end. I know I'm going to learn how to trim a heavy ship (if that's possible).

Well I stopped on my way home from work tonight and picked up a digital scale that reads in pounds and ounces. I just could not stand not knowing what this sucker weighs. The digital scale improved the readout it says....................3 lbs. 11 oz. so the old scale was off by 1 oz. we are at 59 oz. Well, yeah I'm a little disappointed I was hopeing the bargin scale was off. This plane has been sanded so much that I'm afraid to sand anymore or else you won't be able to even pick it up without crushing it. I will keep you all posted as to it's progress. There's not much you can do to lighten the wings that I hasn't already been done. The fuse is as light as I dare make it. So it is what it is!!!!!! Some of you have said I will have a good time flying it anyway so that is good news. I fly intermediate so if Porky the Pig is up to the task I'm also game. As soon as Pig is done I will start another. It's time to get on with it. Hey it's not so bad I just remembered I have a SV-11 somewhere up here on the shelf. I think it will be a killer ship.......Grins
Thanks Again to All of You
P.S. In my spare time I will pump iron...later

proparc · « **Reply #22 on:** July 07, 2006, 10:27:30 PM »

Hi Greg, this is Milt. If you want to be ABSOLUTELY SURE about having enough power to pull your Magnum, the Saito 56 will settle the issue! If you get one, I will help you break it in, set up the tank and help you with the prop. As I have stated in another post on the Sig Magnum; I didn't then and don't now feel that the ST 51 is the way to go on this plane,(I am talking from actual experience). Whatever you do, try to stick to true 60 class power on the Magnum. But, feel free to use whatever you feel will be appropriate FOR YOU.

Milt

Ron King · « **Reply #23 on:** July 08, 2006, 12:10:41 PM »

I still think you will be happy with this plane. I figure about 6 ounces for a reasonable finish and that will put you in the 65 - 66 ounce ballpark. The Magnum certainly has enough wing to handle this weight with no problems at all.

I would also agree with Milt - that ST 51 might not be enough for this plane. I powered my first Legacy (64 ounces) with a Saito 56, then made the mistake of switching to the ST 51. Ouch - wrong way to go for power.

I learned my lesson very fast, switched to a RO-Jett 61, then a 65, now a 76.

The plane (and the pilot) are much better and happier now.

I won't knock the four stroke engines. I didn't know how to make them work for control line when I came back to this side of the hobby. I could probably make the 56 work now - it's here in the basement - but I have moved on to piped two strokes and electrics.

Take care,

Ron

Kerry Ewart · « **Reply #24 on:** July 08, 2006, 05:43:07 PM »

A trick that a friend of mine(Joe Parisi) told me when sheeting foam wings/stabs is to give the wing skin a coat of 50/50 thined dope,Sure it will curl but at least it curls the right way.Then apply the epoxy to the wing skin not the foam core like greg said and you can cut your epoxy amount in half as well as you can thin yor epoxy as well.We have also sheeted 650 Sq planes in 1/32 balsa as skins this works fine too as you can get better balsa this way .
I have skinned a wing using this method with about 1 oz of epoxy,Do some tests and try it yourself.

Greg L Bahrman · « **Reply #25 on:** July 08, 2006, 11:00:46 PM »

Quote from: Kerry Ewart on July 08, 2006, 05:43:07 PM

We have also sheeted 650 Sq planes in 1/32 balsa as skins this works fine too as you can get better balsa this way .

I suspect my skins were close to 1/32 as I block sanded them on both sides before attaching them to the foam cores. Also blocked them after the epoxy set. I started with 1/16 sheet. Thanks for the tips.

Greg L Bahrman · « **Reply #26 on:** July 09, 2006, 04:06:19 PM »

Went to the flying field yesterday to fly with some friends etc. Took my sons P40 ARF and thought I would put in a couple of fun flights. It still needs some trimming although he doesn't care as long as it makes noise and goes in a circle he's happy. Nice to be young. As I was sitting watching the others a fellow stopped by asking if anyone would be interested in a new RO 61 side exhaust. Has it been run? NO, Do you have the original box, YES. Do you have the original receipt,YES. Price was right so it now has a new home. Left promptly and worked all day making new engine plates and modifying the cowl etc. The RO is wider and longer than the ST 51 so the fuse had to be extended about 3/16 in. You really can't tell any difference from the outside. I think this will be a step in the right direction don't you. Of course now it begs the question, can you replace the 61 with a 65 ? (same case size?) Anyone know?........... Hey I found it on the RO-Jett Web Site. The 51, 61, 65 and the 76 all have the same mount. That will lead to some sweet dreams. You think?
RED HOT DEAL !!!! Milt,
Thanks for the offer, real kind of you. I tried to fit the Saito 56 in and I would of had to cut out the existing firewall behind the motor which I was not willing to do. If I had planned from the start it would have been easy to just to move the firewall back so it cleared the carb. When I started this project I didn't have the Saito. So maybe I'll use it in my next project.
RED HOT DEAL !!!!

Tom Dugan · « **Reply #27 on:** July 09, 2006, 04:25:49 PM »

Greg,

Coming on the ROJett 60 sounds as if it was meant to be. I hope it works great. Im very anxious to hear how your Magnum flys.

I have two engines I'm considering for mine, a ST V60 or an Enya 60 worked by Scott Reise. I lean toward the Enya, always liked them.

Good luck...Thomas

Greg L Bahrman · « **Reply #28 on:** July 09, 2006, 06:05:23 PM »

Yeah Thomas,
About the RO-Jett, I gotta admit I was pretty excited especially since the motor width turned out to be close to the width or just a little wider than the ST 51...........If you use either the ST60 or the Enya 60 you have to split the fuse formers vertically and add maybe 1/8 to 3/16 in. to the width as the mounting lugs on both motors are wider than the ST 51. I don't remember the exact extra width needed but I remember there was mention of this in the plans.

Randy Powell · « **Reply #29 on:** July 09, 2006, 07:01:39 PM »

Greg,

The RO-Jett will have plenty of power. Especially running 4-2-4. Very cool.

While I was waiting for the new molded bottom block for my plane to dry, I decided that I would go ahead and fit the RO-Jett .65 I have into it. Only mods were some slight (and I mean slight) angling on the engine mounts (the RO_Jett is maybe a 1/16 wider than the OS that was in there) and relocating the needle valve exit. That's it. So when it's back in the air, it will have more power.

The original tank is 6.5oz. Should be enough. We'll see. And I have to make new gear since I barely had the ground clearance for the OS and a 11.75" prop. I put an extra inch and an eight length to the gear to accomodate what will likely be a much bigger prop. At least 12.5 inches.

Jim Oliver · « **Reply #30 on:** July 09, 2006, 08:08:00 PM »

With two Magnum kits in a holding pattern above my building board, I am very interested in what you Magnum builder/fliers are up to.

I actually got so far as to sheet the wings from one kit, only to discover that the two cores have different airfoils.

I have a borrowed Millennium wing jig to build two Magnum wings--soon, I hope.

Keep the reports flowing, please.

Jim

Ron King · « **Reply #31 on:** July 10, 2006, 06:01:52 AM »

Greg,

This is exciting news. Congrats on the new engine. It will definitely take care of your power situation.

The 65 and 76 do fit the same mounts. The 76 is 1/8 inch taller, so the exhaust would be lower in your fuselage. I use a shorter header rise to keep the pipe in the same place. (All rear exhaust on my planes.) You can file or forget this info.

Your 61 should be fine. Hot tip: This engine just LOVES the Stalker 12 x 6 three blade prop. Contact Kaz Minato to get some.

EDIT: I should mention that this prop is for non-piped motors. It specs out to about 12 x 5.5" and runs great with a muffled 61. I'm sure a Bolly has something equivalent.

Take care,

Ron

Greg L Bahrman · « **Reply #32 on:** July 10, 2006, 01:31:20 PM »

In doing the engine switch I also removed the 5 1/2 oz. metal wedge tank and will be going to a 6 oz. clunk tank. Will 6 ounces be enough fuel for this bigger engine ?

Ron King · « **Reply #33 on:** July 10, 2006, 01:54:49 PM »

Depends on the venturi size. The stock venturi from Richard is a #12 drill size. Many of us drill it out a little - some drill it out a lot. Last time I checked, Richard drills his to #5 or #6 and uses layers of pantyhose to regulate the power.

My 61 engines were drilled to #8 and I have a 5.5 ounce metal tank in my second Alouette with a rear exhaust, muffled RO-Jett 61. My bigger engines have #9 venturis and do the pattern comfortably with 6 ounce plastic tanks. I run 10 percent fuel in all my engines.

Personally, I would try it out with the stock venturi first and see if it's strong enough for you. You can always drill it out later. It's easier to drill out than to put material back in.

The above info pertains to RO-Jett engines only. Randy's PA engines come with slightly bigger venturis and he states they need more fuel to do the pattern comfortably. I'm breaking in a new PA 75 right now and will have to squeeze an 8 ounce tank into the new Mustang.

EDIT - Whatever tank you use, check the tank centerline against the needle valve. The RJ and PA engines have the needle valves higher off the motor bearers. IIRC, the RJ is 11/16" as opposed to the usual 1/2" - you should measure this and not rely on my memory.

You will probably have to shim your tank, depending on motor pads or etc.

My two cents,

Ron

proparc · « **Reply #34 on:** July 10, 2006, 09:06:41 PM »

Greg,
Rojett 61 side exhaust at a good price! Man, you are good to go!! Fast starting, great power, long life, lite weight. Kiss your weight worries good buy.

Greg L Bahrman · « **Reply #35 on:** July 12, 2006, 02:02:09 PM »

Yeah Milt,

I don't think the bigger motor eleminates the need for a light ship but it sure will be a step in the right direction. I will continue to look for any opportunities to reduce weight anywhere I think I can. It's a little late to be thinking of these things at this time as the plane is basically done. I really was not concerned about the weight until this forum pointed out the necessity to keep things light and I was already at 60 oz. and not even done yet. This only goes to show my lack of building experience and knowledge. Even at this time as I re-evaluate what has already been done I really feel that I could build another foam wing and knock a few ounces off of it. I don't think a bigger motor or more power is the total answer. As Randy said it's still important to keep the static weight down whenever possible. Although if it flys good at 68 oz. with the ST 51. It surely will fly better with a RO-Jett 61 at the same weight. In this sport our planes need to turn sharp (weight problem) and do vertical manuvers (power problem) crisp and clean and this is more a function of the power to weight ratio. I think this has all been a great learning experience for me and the next one will be better.

Greg L Bahrman · « **Reply #36 on:** July 15, 2006, 04:23:21 PM »

Quote from: Ron King on July 10, 2006, 06:01:52 AM

Greg,
Hot tip: This engine just LOVES the Stalker 12 x 6 three blade prop. Contact Kaz Minato to get some.

EDIT: I should mention that this prop is for non-piped motors. It specs out to about 12 x 5.5" and runs great with a muffled 61. I'm sure a Bolly has something equivalent.
Take care, Ron

Hey Ron,
Props got here today...They are really beautiful, these are really sweet. They are really finished nice, can't wait to give them a go. Thanks

frank carlisle · « **Reply #37 on:** July 15, 2006, 05:25:01 PM »

Greg,
This is getting to be a long thread and difficult for me to read through to get up to speed. But I made it!!
The new Ro-Jett will probably do wonders for you. And your enthusiasm level is much better than it was in your first few posts. Way to go man.
You mentioned that you figured you could build the NEXT one better. And I think that if you start a new one pretty soon after this one is done you'll have a super model.
You already know what you would do different to keep the weight down on number two. And flying number one will give you ideas on making number two not just lighter but a better flyer too. So....stick with this design at least through one more edition.

Greg L Bahrman · « **Reply #38 on:** July 15, 2006, 08:38:32 PM »

Quote from: frank carlisle on July 15, 2006, 05:25:01 PM

Greg,
The new Ro-Jett will probably do wonders for you. And your enthusiasm level is much better than it was in your first few posts. Way to go man.

Hi Frank,
Most of us are not like Sparky with his building speed and talent. Between family, health and work and my own short comings etc. it takes me almost a year to complete a decent ship and then to discover it's all been a waste of time really hurts. As it turns out those with more experience than me have said don't stop now keep on moving to completion. So as Buzz Lightyear always said "to infinity and beyond" !!!