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Ben Buckle Majestic Major help

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David H20/06/2020 13:56:36
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I bought an aged Ben Buckle Majestic Major yesterday (blimmin big innit) that came with an ASP 0.91 four-stroke – both in need of some TLC. Largely a winter project.

I see that there has been forum discussion on this remarkable looking model – with at least one person who owned one (no longer with the forum).

Majestic Major

Can anyone who has built or owned a Majestic Major please tell me what the C of G position - and any other valued info concerning control surface throw magnitudes and Tx settings?

PS. I too, like some others, am a prodigal son. I joined (and later left) this forum eons ago when living in North Wales - now returned to civilisation (no offence). Re-joined the BMFA and have registered with the CAA and passed their test so I’m kosha! A joy to return to the fold - despite spending squillions this past year on re-kitting out 😊

[How do I get the font right please?]

Frank Skilbeck20/06/2020 16:57:45
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4752 forum posts
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I've got my Dads old one, powered with a Laser 62, balances on the spar, elevator movement around 10-15mm each way and rudder as much as I can get around 25-30 mm each way. Lovely flyer, you might have to stop the 91 to get it to land as there maybe enough thrust on tickover with a 91 for it to keep flying.

David H20/06/2020 17:35:11
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Thank you kindly, Frank, for the info. Very helpful.

There is no single spar, instead there are the three 4mm diameter metal rods - two to the front (one above the other) and one to the back. I'd guess it's the front two?

Gary Spicer 124/06/2020 11:57:13
46 forum posts
3 photos

COG for Majestic Major as Frank says dont use excessive elevator throws 3/8 inch on plan = 10mmbb cog.jpg

paul d24/06/2020 13:16:39
189 forum posts
22 photos

I had a majestic major years ago, overpowered with a Irvine 61.

The cg position shown above will work.ok, as to throws, elevator very little, rudder as much as possible.

I'm currently flying a just junior which is just a smaller junior 60 and a much smaller majestic major, they all use the same set up regarding throws etc...

You will have fun with that, you'll also be surprised how little power they need to fly!

Just read Frank's post above and I totally agree with his comments, don't suppose you've got a .60 4 stroke you could put in it?

Edited By paul d on 24/06/2020 13:20:06

David H24/06/2020 16:21:02
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Thank you kindly Gary and Paul for the info.

The forward CoG position shown on Gary's drawing (above) corresponds to approx. 110mm from the leading edge, which is where the two metal bars (one above the other) that join the wing halves are located.

I've also done a bit or nerdery and calculated the Tail Volume Coefficient to be about 0.5. This corresponds to a CoG of 29% x Chord (from leading edge), which on the Maj Maj is 29% of 370mm = 110mm!! QED.

29% is half way between generic CoG limits of 25% to 33% of Chord. Sounds just like a Ben Buckle pragmatic engineering compromise i.e. in a dilemma add 'em together and divide by two!!  Perfect.

The previous owner of put a very robust tail wheel on (none at all on the original model). Given the significant lever arm of about 1.1m it made it very tail heavy. So to balance the thing out a squillion tonnes of lead were added to the front of the plane below the engine. Might explain a .91 instead of a .60.  Surprised it wasn't a 1.60 wink

Talking of the engine, gave it a clean by overnight soak in nitro and then the use of a tooth brush next day. Went from this:

ASP 0.91 FS

to this:

1.jpg

2.jpg

3.jpg

Not bad, eh. No need to use the antifreeze in the slow cooker trick. I'm well pleased. Runs quite well too - should be prefect after some carb mixture adjustment:

4.jpg

Change to a .60? Mmmmmm...maybe. I'll see how it flies first with the .97. and how much I could get a used 0.6 for and what I could sell the 0.91 for. There again, I could just keep the 0.91 as an appreciating asset and for possible use in a later model.

An 'expert' told me it's better to have excess power (not too excess) rather than inadequate power cos (he said) you just power back on the throttle. He thought the .97 in the Maj Maj would be fine - heck, the former owner of the Maj Maj evidently found the same.

Once again, guys, many thanks for your helpful contributions. yes smiley

 

Edited By David H on 24/06/2020 16:27:25

Frank Skilbeck24/06/2020 17:12:27
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4752 forum posts
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Posted by David H on 24/06/2020 16:21:02:

An 'expert' told me it's better to have excess power (not too excess) rather than inadequate power cos (he said) you just power back on the throttle. He thought the .97 in the Maj Maj would be fine - heck, the former owner of the Maj Maj evidently found the same.

Once again, guys, many thanks for your helpful contributions. yes smiley

Edited By David H on 24/06/2020 16:27:25

Possibly but I think you'll find that on the Majestic Major it will quite happily fly on tickover on a 91 FS, so you may need to cut the engine for landing. Mine flies on an old Laser 62 with a 15 x 4 prop.

Robert Welford24/06/2020 17:25:26
205 forum posts
4 photos

I have a Belair Super 96 (slightly bigger MM) to build, but it has yet to reach the top of my build list.

However, during lockdown I acquired a S/H Majestic Major. The previous owner had a Saito 82 in it and installed the elevator servo in the tail.

I've re-engined it with a Laser 70 and installed my radio gear again with an elevator servo in the tail. Surprisingly the CofG is within the range indicated on the plan.

I flew it last week for the first time. It has no downthrust and minimal right thrust and I found that it has significant pitch changes with power and requires right rudder trim. I put in a some nose weight (~500g) and it made no difference. Once trimmed at low power setting it was fine.

It is well overpowered with the Laser 70.

I have now put in 2.0 degree so I hope the power/pitch coupling will be reduced. Out of interest how much down thrust and side thrust have other MM operators used?

paul d24/06/2020 17:50:11
189 forum posts
22 photos

It's worth remembering that the j60 was originally a free flight model, short climb/ engine run to height then a circular glide back to earth. You really need to treat it's big brother sort of the same.

Not sure my major had any side/ down thrust, I just used to climb to height, cut the motor back to tickover and float around a bit until it was time to climb back up again, very relaxing ( some may well think it boring but that's fine).

David, don't worry about the cg, as long as it's somewhere near she'll be just fine although I really would consider a smaller engine.

Robert Welford24/06/2020 19:17:29
205 forum posts
4 photos

Yes Paul, I agree it's a guided freeflight model and not an F3A model. However, it would nicer to fly if there was less pitch throttle coupling. Hopefully, the addition of 2 degrees down thrust will improve things.

DCW24/06/2020 20:29:21
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98 forum posts
66 photos

Hi David.

Back in the last century, (1986), I had a Majestic Major mine balanced on the main spar. It was the first RC aircraft that I went solo with. Mine had a now vintage OS 61 four stroke with open rockers and a 12x6 prop. It made a lovely sound.

Majestic Major at Keevil

With ballast, (quite a bit), mine weighed about 8.5lb, but this was fine it was still a 'floater' on a fast tick over.

Enjoy the MM, regards David

Paul Marsh24/06/2020 20:31:54
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4072 forum posts
1225 photos

I have one with a Mk1 OS 60FS. More than enough power. A modern .91 would pull it vertical and hold it there as well as go like a rocket!

maj_major (3).jpg

maj_major (2).jpg

PatMc24/06/2020 20:50:19
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4433 forum posts
538 photos
Posted by Robert Welford on 24/06/2020 17:25:26:

I've re-engined it with a Laser 70 and installed my radio gear again with an elevator servo in the tail. Surprisingly the CofG is within the range indicated on the plan.

I flew it last week for the first time. It has no downthrust and minimal right thrust and I found that it has significant pitch changes with power and requires right rudder trim. I put in a some nose weight (~500g) and it made no difference. Once trimmed at low power setting it was fine.

You should move the cg rearwards then re-trim to reduce pitch changes caused by power changes.

Paul Marsh24/06/2020 22:31:28
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4072 forum posts
1225 photos

The model is not designed to fly fast, and overspeed would cause a pitch up. The flat bottomed wing will cause that, and even on full power, the old OS60fs will cause a slight pitch up.

Don't forget, these models were originally flown on tiny, engines, sparkies with little power, a .60 had the power of a .25 and it would fly on a modern .25 if need be.

Robert Welford24/06/2020 23:32:48
205 forum posts
4 photos

I appreciate the fact that the MM is basically an enlarged vintage free-flight model.

Nevertheless from a modest power setting from engine on to engine off it should remain vaguely in trim, but my MM doesn't hence the need for downthrust so it glides ok when power off .

 

.

 

Edited By Robert Welford on 24/06/2020 23:33:21

PatMc25/06/2020 00:01:26
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4433 forum posts
538 photos

Robert, engine on to engine off was a binary event when these models were free flight. They relied on being trimmed for one power setting but we now have throttle & elevator. If a model is pitching up unduly when power is increased it's probably nose heavy &/or over elevated. Being overpowered won't help you could try the old FF trick of fitting the prop back to front.

Denis Watkins25/06/2020 05:49:07
4544 forum posts
123 photos

Have read through the post Robert, and must comment on adding double the required I/C power to any model.

When " too large " An I/C motor is fitted to an airframe, the motor never reaches Operating Temeperature

The motor never gets hot enough to run at full power properly and tootling round at tickover and low idle and

Increases the chances of a deadstick.

You never get to use the throttle properly throughout the flight, so the flight teaches you nothing of stick technique.

As others have said, this airframe has no benefits by over powering it.

This is not " useful weight " on the front any more, a little 48 4S and a lump of lead is a lot more useful.

Market the 90 well and buy a little 4S and 2 gallon of fuel

David H25/06/2020 08:55:34
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Wow, what fab contributions. Super pics. Wonderful, and very much appreciated!. Thank you all.

I like slooooow flying. Powered gliders great. I have a 2.6m wingspan RADIAN XL. Get it up and have a loooong float around. This is my first excursion into i/c. Been all elec since when I stared in 2005. But, have lurved the sound of a purring 4-stroke.

The 0.91 in the Maj Maj is a mystery. The previous owner did a good job building and finishing the model - especially the tail wheel mod (impressive). Knew what he was doing and did it well. The amount of 'gunk' on the engine evidences it had been well used - of course it could be a second-hand unit left unclean. But, the fact is the previous owner/builder made a deliberate choice to use heavier and more pricey 0.91 power instead of a 0.60. I surmise he (or a she, maybe) had a robust reason for doing so. There lies the mystery! Why?

If I change to a 0.6 now it's hassle. Lighter engine = putting on more ballast. Smaller engine = new alloy engine mounting plate - I don't have the means to do this so I'd have to pay for one to be made. Importantly, I'd never know how the Maj Maj flies with the 0.91!!

In effect, the decision has been made for me. Give it a go with the 0.91 and see what happens - then re-assess nerd

PS. 10.6lbs is marked on the rear underside of the model. Using bathroom scales it comes out about same. 2.1lbs heavier than that of DCW (i.e. 25% heavier). I did mention earlier the tonnages of lead in the front of the model to counterbalance the tail wheel addition.

 

.

Edited By David H on 25/06/2020 09:01:57

Robert Welford25/06/2020 10:16:13
205 forum posts
4 photos
Posted by Denis Watkins on 25/06/2020 05:49:07:

Have read through the post Robert, and must comment on adding double the required I/C power to any model.

When " too large " An I/C motor is fitted to an airframe, the motor never reaches Operating Temeperature

The motor never gets hot enough to run at full power properly and tootling round at tickover and low idle and

Increases the chances of a deadstick.

You never get to use the throttle properly throughout the flight, so the flight teaches you nothing of stick technique.

As others have said, this airframe has no benefits by over powering it.

This is not " useful weight " on the front any more, a little 48 4S and a lump of lead is a lot more useful.

Market the 90 well and buy a little 4S and 2 gallon of fuel

Hi Denis,

The OP was by David H not me!

I only interjected to ask whether people with MMs built in the 2 degree down thrust as depicted on the plan. The MM I acquired did not have it and IMHO it needs it irrespective of the engine size.

I installed a Laser 70 because I have one (in fact two) and they easy to operate and "purr", but not to be used at 'full-chat'. My experience is that Laser engines are fine running all day at reduced throttle settings.

I have a Rohma (similar to Junior 60 - similar vintage) originally powered by a ED 3.46 Hunter (currently an OS 30 FS) and the power on/off trim is fine.

Robert

Denis Watkins25/06/2020 10:31:00
4544 forum posts
123 photos

Apologies Robert, I can see my mistake, should have been David

And your 70 is a different ballgame, " just " on the larger line

Davids 90 is nearer twice as powerful as the model needs to be.

I still believe you don't really get a full range of throttling experience with an overpowered vintage model.

I would still fit the correct motor size and some lead and use all of the throttle stick

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