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Author Topic: Charles Mackey - Monster FM Feb/Mar 1961 engine offset?  (Read 3556 times)

Online Dennis Toth

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Charles Mackey - Monster FM Feb/Mar 1961 engine offset?
« on: October 28, 2020, 09:41:14 AM »
Anyone have a scanned copy of the . February/March 1961, page 17, Flying Models, “Monster” (offset engine/wing) by Charles Mackey? I am curious about his thinking with the big offset out thrust of the engine in this series of design he did. I think this is the extreme in engine offset (I think the BiSlob is close) and wondered if he gave any design insight about it's use and how it actually impacted performance.

Best,   DennisT 
« Last Edit: October 28, 2020, 06:55:42 PM by Dennis Toth »

Offline Steve_Pollock

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Re: Charles Mackey - Monster FM Feb/Mar 1961 engine offset?
« Reply #1 on: October 28, 2020, 07:16:03 PM »
Dennis, not the best copy, but readable (part 1)

Offline Steve_Pollock

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Re: Charles Mackey - Monster FM Feb/Mar 1961 engine offset?
« Reply #2 on: October 28, 2020, 07:17:06 PM »
(part 2)

Offline Steve_Pollock

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Re: Charles Mackey - Monster FM Feb/Mar 1961 engine offset?
« Reply #3 on: October 28, 2020, 07:17:34 PM »
(part 3)

Online Brett Buck

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Re: Charles Mackey - Monster FM Feb/Mar 1961 engine offset?
« Reply #4 on: October 29, 2020, 10:30:15 AM »
Anyone have a scanned copy of the . February/March 1961, page 17, Flying Models, “Monster” (offset engine/wing) by Charles Mackey? I am curious about his thinking with the big offset out thrust of the engine in this series of design he did. I think this is the extreme in engine offset (I think the BiSlob is close) and wondered if he gave any design insight about it's use and how it actually impacted performance.

   Note that this large offset is still straight through the CG, rather than causing a huge thrust line offset. So to first approximation it creates no torque in yaw. Large amounts of offset in a conventional model also causes a huge amount of yaw torque (which I contend you don't want). This one just aims the engine out to get some more line tension, it (to first approximation) doesn't create a lot of yaw torque at the same time. The approximation being that there is still a fin/rudder on it.

      So, simplistically, all it does is put some of your maybe 1 lb of thrust pulling on the lines. That is feeble compared to the 6ish lbs you would get from centrifugal force, which is why it isn't very effective. The added line tension F=thrust*sin(offset angle), figure you have 1 lb of thrust in flight, the offset angle is about 30 degrees, eyeballing it, so 8 ounces of added line tension, and 14% loss of maneuvering thrust (f=thrust*cos(offset angle)).

     So, engine offset is a feeble source of extra line tension if it goes through the CG.

      Howard keeps telling me that this sort of reasoning is simplistic, which is it, but so far I have seen nothing about thrust offset that is not pretty predictable from looking at the thrust vector.

       Brett

Online Trostle

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Re: Charles Mackey - Monster FM Feb/Mar 1961 engine offset?
« Reply #5 on: October 29, 2020, 01:30:50 PM »
Charles Mackey had two designs published with his approach to using an offset engine.  One is the Monster shown above for a Fox .29 or .35 in the Feb 62 issue of Flying Models.  The other is the smaller Red Wing, Dec 63 issue of Flying Models.  This has a span of about 34" span, weighs 8 oz, with an .049 Frog Diesel.

I saw a Monster fly at Whittier Narrows around 2000.  I do not know who was flying it.  I do remember it was windy, at least the kind of wind that most people do not like to fly in.  The model was doing a recognizable stunt pattern.  I think it was in one of the maneuvers at the top of the circle were the wind pushed the model towards the center, trailing many feet of loose lines.  It was like the airplane realized it did not belong there and immediately went out to the end of the lines with no further incidents.

There is another design with the engine offset through the CG.  This is the Charger by Jim Mayfield (a very good flier in Southern California in the 60's), in the Oct 1970 issue of American Aircraft Modeler.  This was a more conventional lay out with a profile fuselage, swept back wing and a tail.  The TD .049 was mounted inboard section of the outer wing, the thrust line apparently went through the CG.  Mayfield wrote that "as a competition machine, the ship is not quite up to form.  He wrote that since the engine and tank were close to the CG, it turned "instantly. 

A little off topic here, but a good place to mention the Strato-Liner, Feb 1957 issue of Model Airplane News by Carl Risteen.  This 32" monster had a basically typical configuration with fairly large flaps and elevators.  It had two McCoy .049 diesels, one conventionally mounted on the nose of the airplane, he other mounted on the outboard tip with 65o offset "from straight forward".  It could fly on 200 foot lines.   Article does not mention, but with 200 foot lines, lap times would be in the probable range of 20 seconds.

Interesting stuff.

Keith
« Last Edit: October 31, 2020, 10:49:07 AM by Trostle »

Online Brett Buck

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Re: Charles Mackey - Monster FM Feb/Mar 1961 engine offset?
« Reply #6 on: October 29, 2020, 03:06:41 PM »

I saw a Monster fly at Whittier Narrows around 2000.  I do not know who was flying it.  I do remember it was windy, at least the kind of wind that most people do not like to fly in.  The model was doing a recognizable stunt pattern.  I think it was in one of the maneuvers at the top of the circle were the wind pushed the model towards the center, trailing many feet of loose lines.  It was like the airplane realized it did not belong there and immediately went out to the end of the lines with no further incidents.


   Yes, exactly - - all these methods to "manufacture" line tension are geared towards quick recovery of line tension if it is lost, Rudder offset, for instance, turn the airplane right/outboard as soon as the line tension goes away, and the only thing stopping it from a hard right turn is that the lines keep it from going any further.

    The issue with most of these methods is that you can't afford to have the line tension fighting some other setting like rudder offset, because as soon as you have one adjustment fighting another they can only be balanced against each other in one steady-state condition. Change either the tension, or the velocity, and it has to maneuver to try to get to a different equilibrium yaw angle, and if these are changing frequently, it just wallows around trying to get to the right angle - and whipping up a third problem, the lines. So it hurts you when you *have not* lost line tension, just due to normal variations.

    Offset rudder or offset engine (in the conventional position) creates torques you have to oppose with line tension. Engine offset like this one (where the engine is angled AND moved to that the thrust vector still goes through the CG) is much less prone to this problem under normal circumstances - although not entirely, because you still have a rudder getting blown on by the engine.

   Brett

Online Dennis Toth

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Re: Charles Mackey - Monster FM Feb/Mar 1961 engine offset?
« Reply #7 on: October 29, 2020, 08:06:32 PM »
Thanks Steve for the post. I find this design very interesting, looks like a fun ship that will get attention. Would be interesting with retract gear. The tank looks different, has anyone tried one of these? It seems to be similar to a chicken hopper but the hopper is the front part of the tank rather than on the side. Not sure how you could incorporate uniflow into it.

Best,   DennisT
« Last Edit: October 30, 2020, 01:13:00 PM by Dennis Toth »

Online Dennis Toth

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Re: Charles Mackey - Monster FM Feb/Mar 1961 engine offset?
« Reply #8 on: October 30, 2020, 01:15:30 PM »
I think this would make a great electric ship with retracts. What package would work with this?

Best,   DennisT

Online Dennis Toth

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Re: Charles Mackey - Monster FM Feb/Mar 1961 engine offset?
« Reply #9 on: October 31, 2020, 07:20:58 AM »
Steve,
Keith mentioned the Red Wing ship that was published in the Dec-Jan issue of Flying Models I'm not sure if it was it was in 1962 or later. Both these ships are in Tom Morris's Control Line Classic book. If you have the Red Wing article and could post it would be interesting to see the different thinking between his two designs. The Red Wing used I think an 049 diesel so it could turn a good size prop an 09 glow would probably work. On the Red Wing it seems there is less sweep so the CG is a little further forward. Looking at that this it seems that you don't want to get it nose heavy as it would create a moment that would turn the ship in and defeat the purpose of the offset.

Would be a fun first crack at this design. Still think electric would be the way to go here.

Best,    DennisT

Offline Steve_Pollock

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Red Wing
« Reply #10 on: October 31, 2020, 09:19:04 AM »
Dennis, sorry -- that one is not in my collection, but I'll keep an eye out for it.  It should be in the 1964 December-January issue of FM.

Online Dennis Toth

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Re: Charles Mackey - Monster FM Feb/Mar 1961 engine offset?
« Reply #11 on: November 01, 2020, 07:42:06 AM »
Just curious, if you built this with an open or removable cowl (that could be left off) and since back of the fuse/rudder is only 1/4" sheet would the Monster be profile legal?

What I'm thinking is you might be able to get two event ships from one model.

Best,    DennisT 

Offline John Miller

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Re: Charles Mackey - Monster FM Feb/Mar 1961 engine offset?
« Reply #12 on: November 01, 2020, 11:41:45 AM »
Dennis, neat idea, but look closely at the fuse. The fuse top block is 1/4 balsa, but the fuse sides are 1/8 balsa, and the elevator pushrod runs inside the fuse.  Consider, with a 1/4"space between the fuse sides, the fuse could be a total of 1/2 inch thick, but the pushrod and horn might be a bit tight.

By looking at the width of the 1/4" elevator fairing that fits between the elevator halves at the center trailing edge, as well as the "carved to shape" bottom fuselage block, I get the impression that the fuselage section may exceed the 3/4" width at the wing trailing edge required for a profile. I fail to see any detail that sets the width of the fuselage. You, of course, could interpret this differently.


Leaving the cowl off the engine compartment would expose the mounting bolts as prescribed, but might cause changes in airfoil asymmetry, drag, and engine ``cooling.

Still, it's a neat idea.

I like your earlier idea of E-power better, but not too sure of the efficacy of retracts. To me, it appears that the single mono wheel would interfere with the bellcrank when retracted.

As I've been attracted to this design for years, even discussing to some length and detail with the designer, I've wanted to convert the drawing to CAD. I think that I'll have to move that idea up the list.

John

NOTE: I just took another look at the plans and found something related to the width of the fuselage. Above the inboard wing, there's a detail not well identified, that shows the fuselage construction and width. it is definitely too wide to be a profile. I can now see that the triangular-shaped hidden lines at the center trailing edge also relate to the fuse.

There is a possibility, looking at the 3 optional variations on the plan, the fuselages seem much narrower. though I still believe the 3/4" wide fuse may be too tight for the pushrod and horn.
« Last Edit: November 01, 2020, 12:00:58 PM by John Miller »
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Online Dennis Toth

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Re: Charles Mackey - Monster FM Feb/Mar 1961 engine offset?
« Reply #13 on: November 01, 2020, 02:18:43 PM »
John,
I see what you mean that former is a bit wide and I agree it is to wide for profile rules. Perhaps on could do a take-a-part and with a couple bolts could do a two part fuse that would drop in. Not sure if the flap center section would be considered part of the fuse or just a fixed section of the flaps if it is glued to the trailing edge. If is doesn't have a fillet and is not glued to the fuse I think it would be consider part of the wing. On the profile fuse it could it would just be a straight sides just wide enough to cover the pushrod and horn. Either way if I get around to build it i will go the electric route. Do you have a .pdf of the plans you could post?

Best,     DennisT

Offline John Miller

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Re: Charles Mackey - Monster FM Feb/Mar 1961 engine offset?
« Reply #14 on: November 01, 2020, 07:04:01 PM »
Hi Dennis, Yeah, it is a neat, kinda tricky idea to make a flying delta wing aircraft out to be a profile.

I'm sorry, I had this monster down the list, where other projects kept bumping it down the queue. When I get it done, I'll let you know though.

John
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Online Dennis Toth

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Re: Charles Mackey - Monster FM Feb/Mar 1961 engine offset?
« Reply #15 on: November 02, 2020, 10:34:01 AM »
John,
I managed to get this to a .pdf format that might be easier to work from for CAD. Also allows taking it to Kinko's and getting full size.

Best,    DennisT

Offline John Miller

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Re: Charles Mackey - Monster FM Feb/Mar 1961 engine offset?
« Reply #16 on: November 02, 2020, 02:46:30 PM »
Thanks, Dennis, I've downloaded the PDF file for use when I do the CAD plan.

I'm thinking like you are, electric power would be good for this design. Why? It would keep all that castor and fuel out of the interior of the wing.

John
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Offline Peter Nevai

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Re: Charles Mackey - Monster FM Feb/Mar 1961 engine offset?
« Reply #17 on: November 06, 2020, 05:45:45 PM »
Speaking of the Charger, My Dad upscaled the model for a OS20. I could fly that airplane like a BiSlob if I let it bleed off enough airspeed. It flew very well. Plans attached
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Offline phil c

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Re: Charles Mackey - Monster FM Feb/Mar 1961 engine offset?
« Reply #18 on: November 28, 2020, 10:26:24 AM »
Just curious, if you built this with an open or removable cowl (that could be left off) and since back of the fuse/rudder is only 1/4" sheet would the Monster be profile legal?

What I'm thinking is you might be able to get two event ships from one model.

Best,    DennisT 

People tend to get very picky about some things.  I prefer fun.

For the Monster run a 5/8in. wide strip of 1/4in balsa top and bottom and meeting at the leading edge.  Square the 1/4" at the elevator hinge line.
Voila'  a 5/in. wide .

To make it even more rules scrutiny proof, add two ribs space to be 3/8in spacing, 5/8in. wide under the center sheeting to make a "true" fuselage.  From experience, I'd put the bellcrank completely in the left panel and the control horn in a left wing mirror image position.  Having it on the right puts it right in the exhaust/leaking fuel/blowby  area.

Phil C
« Last Edit: November 28, 2020, 11:00:16 AM by phil c »
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Offline phil c

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Re: Charles Mackey - Monster FM Feb/Mar 1961 engine offset?
« Reply #19 on: November 28, 2020, 10:58:00 AM »
Hi Dennis, Yeah, it is a neat, kinda tricky idea to make a flying delta wing aircraft out to be a profile.

I'm sorry, I had this monster down the list, where other projects kept bumping it down the queue. When I get it done, I'll let you know though.

John


Heck, put a Delta Dart fuselage on it, complete with pointy nose, canopy, tail fin.
phil Cartier

Online Dennis Saydak

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Re: Charles Mackey - Monster FM Feb/Mar 1961 engine offset?
« Reply #20 on: December 23, 2020, 02:29:14 PM »
I have an annotated full size copy of the Monster plan, which contains some important information about tank construction. I don't know who wrote the notes, possibly Mr. Mackey himself?

 
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Offline PerttiMe

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Re: Charles Mackey - Monster FM Feb/Mar 1961 engine offset?
« Reply #21 on: March 27, 2021, 02:42:38 AM »
I see that a Monster plan has been submitted and posted on Outerzone: https://outerzone.co.uk/plan_details.asp?ID=12884

That one does not have the notes.
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Online Dennis Toth

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Re: Charles Mackey - Monster FM Feb/Mar 1961 engine offset?
« Reply #22 on: March 28, 2021, 07:50:21 AM »
The tank is a form of uniflow/chicken hopper. This would make a great electric project. Mackey did several other ships with this high off-set thrust line through the CG but not much is know about them. It is an interesting idea for high wind conditions.

Best,    DennisT

 
« Last Edit: March 30, 2021, 11:12:29 AM by Dennis Toth »

Online Dennis Saydak

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Re: Charles Mackey - Monster FM Feb/Mar 1961 engine offset?
« Reply #23 on: March 28, 2021, 08:40:48 AM »
I managed to build one during the Covid lockdowns. It is now covered in Polyspan & clear dope. I don't have any tin stock on hand so I haven't  attempted to make the tank yet. The tank can be removeable and it slips into the tank compartment between the motor mounts. There isn't much room inside the cowl to attach the fuel line to the NV. I expect that the fuel line will have to exit the bottom of the cowl and connect to the NV through a hole in the cowl. Here's a picture of mine "in the bones".

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Online Dennis Toth

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Re: Charles Mackey - Monster FM Feb/Mar 1961 engine offset?
« Reply #24 on: March 30, 2021, 01:23:40 PM »
Dennis,
The ship looks great. What engine do you plan to use? For the tank if you are using an ABC engine that will run in a fat 2 cycle you could consider a bladder tank. The metal one he came up with is a kinda chicken hopper with uniflow. Evidently, Mackey tried a standard stunt tank and it didn't work at all. I think it was because the back is angled the wrong way.

Please keep posting up dates. This is a very interesting ship and the idea that the thrust line is through the CG and should fly very strong in the wind.

Best,    DennisT

Online Dennis Saydak

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Re: Charles Mackey - Monster FM Feb/Mar 1961 engine offset?
« Reply #25 on: March 31, 2021, 09:36:52 AM »
I have it set up for a Fox .35 stunt. It would be virtually impossible to fit a different engine at this stage. I had the engine mounted with all four bolts on the motor mounts before gluing the mounts into the wing. That way I knew that the mounting bolts would all line up correctly after gluing them in. I live in the country and need to go into Winnipeg to obtain some sheet metal for the tank. I am avoiding that trip because of Covid.

There is an interesting article on Flying lines about problems with baffles in commercially made stunt tanks. That may have been the cause of Mackey's engine cutting out during outside maneuvers? Here's the link: http://flyinglines.org/orin.tanks.html
« Last Edit: March 31, 2021, 09:56:40 AM by Dennis Saydak »
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Online Dennis Toth

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Re: Charles Mackey - Monster FM Feb/Mar 1961 engine offset?
« Reply #26 on: March 31, 2021, 07:02:54 PM »
Dennis,
I see what they are talking about but the Mackey tank is not just a Uniflow with a baffle, it is a chicken hopper. I think the simplest would be to use a bladder (maybe a pipette tip, combat guys have them) with a regulator (maybe someone can post who sells them). Other option is to see if someone will build the Mackey tank for you.

Best,     DennisT

Offline john e. holliday

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Re: Charles Mackey - Monster FM Feb/Mar 1961 engine offset?
« Reply #27 on: March 31, 2021, 09:26:15 PM »
My self I don't use baffles in metal tanks any more after I started using uni-flo tanks.   If you can find the video of the Tulsa Glue Dobbers plastic tank in use during a stunt flight you will see why I don't use a baffle.  I think on the Monster mounting a metal tank in line wit the center rib using ehaust pressure most problems would be solved.  My opinion D>K
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Online Dennis Toth

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Re: Charles Mackey - Monster FM Feb/Mar 1961 engine offset?
« Reply #28 on: April 01, 2021, 06:30:42 AM »
The problem with the normal mounting of the tank off the motor mounts in the Monster is it kicks the rear of the tank inboard, the fuel wants to run to the top of the tank not the pickup at the rear. The Mackey tank reduces this with the chicken hopper front tank which could be adapted to be uniflow also. Aligning the tank along the rib as John suggests and maybe even kicking the rear out 1/4" as you would on a profile should work. Some internal wood work to get the tank between the mounts could do it. Or just use the pacifier bladder/regulator.

Best,   DennisT


Offline john e. holliday

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Re: Charles Mackey - Monster FM Feb/Mar 1961 engine offset?
« Reply #29 on: April 01, 2021, 12:23:58 PM »
If the fuel is running to the front of the tank, make the tank in reverse with the wide part up front with the pick up also.  A few British designs are like that in their combat planes.  In fact I had a racing plane that the pick up was at the front of the tank. D>K
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Online Dennis Toth

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Re: Charles Mackey - Monster FM Feb/Mar 1961 engine offset?
« Reply #30 on: April 02, 2021, 10:23:33 AM »
That is the idea behind the Mackey tank he just used two tanks, small in front of the large. I have used slant forward tank in speed, they call it a coffin tank with the outside wall having a break near the front that the pickup line goes in.

Best,    DennisT

 


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