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Author Topic: Eclipse MK II Dennis Adamisin  (Read 3943 times)

Offline Chuck Fabo

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Eclipse MK II Dennis Adamisin
« on: December 05, 2024, 02:03:56 PM »
Purchased the subject plan yearsssss ago … I desire to build … some questions …

What is an appropriate engine ? (plan states 3.5 Oz. tank)

Changes you would consider/recommend?

Additional thoughts?

Thanks!








« Last Edit: February 12, 2026, 10:06:58 AM by Bud Morrison »


Offline M Spencer

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Re: “Eclipse MK II”… Dennis Adamisin
« Reply #2 on: December 05, 2024, 08:58:30 PM »
Vaugely Relevant . And Mr Adamisins might appreciate Id seen their things in the mag back in the mid 70s . WITH THIS RESULT . and considered their High A/R  ' experiments ' in contemplateing these back then .
a quater century slips by , & Volia . . . .
What happens if you put a table top on it , and step on it . A normal plane . SPREAD IT OUT .  ;D  ( FLAPS are just between the Wiper & the Lower Intake . )Had to put them somewhere . Figure Tail width ( slipsteam ) for starters .

This was a result of the Adamisin Orange Crate / Eclipse , and other things . Having read em a dozen times .
Another One Id put the flaps a few bays longer & sweep the hingeline . It was done to establish a base line .

In a overhead eight it lifted you . And had superb ' fine control ' on tracking . in rounds .
A dud run & it was hopeless . Like Most THINGS .
Being stroppy , Hit FULL UP out of wingover , 50% by itself it came out clean & level . If you eased & flew it
through it was fine . Ya dinnae wanna buildem too light . This was 72 ounce for 630 Sq In .
Advised to' pull through ' on theengine cut , it overshot my landing point , BY A LAP .
Further , think it was 23 % , Lightning was 27 at a guess , Flew much grippyer .
Half Way for P A I think'd be ideal . Tripped over my 90 % ? 68 in from 78 P - 38 Drawings , for .25s .
As Certain turkies only want to pick holes in em , in their ignorance , leave em to gooble .

This is the same ,but with thicker airfoil & more flap . a big worry with the 21 inch spread , was wotiditdo on the outer .
Wingovers & rounds . on a OS 35 ! , WITH THE ELEVEN BY FOUR PROPS . notonanyother .

Had good support trundling around , good turn . A little Slack in the bellcrank to primary push rod was a major annoyance . MAKE SURE THERES NONE .

Id think , as the thin one liked the wind , but this had more grip , the middle ground would be middle ground , as the blunt other white mew was to grippy & had to be flown every inch .
Which it'd do . But hitting its own slipsteam would cut a wing loose and youd get rekitted . So I dont believe a ' High Wake ' is a good idea wiffem . Like thick blunt trailing edges .

The differance from three adjacent 1/8 wires across , to the wheels , in trim & drag , on the green one , compared to FAIRED legs & wheels was astronomical , on sucha cleanplane . NOTE .

Notta Lotta Frontal Area :

Next I will leave taiplane outers fixed , for a reason or three . The EARS / Aerodynamic counterbalances DO lighten & steady controls . Usefull when its bumpy . More even Handle Load . onna big one .
They were TOO undirectly affixxed , structurally . As fixed ends would give a counter force to control , id think it'd stabilise the rear  by needing more control force ! so a more stable load aft , in turns.



Threw these on primarilly as maybe they wouldnta been done , without those pesky Adamisins having shown the way . I believe BOTH have great potential . Electric in the Lightning would be Far Out
as it'd all fittin the early cowlings . Being sorta SCALE ' Aircraft ' inspired . Old Boy . Thanks Dennis & Dave & All . All thiose hours & money , and its all your fault .  ;D   S?P  well . . . . . . H^^




« Last Edit: December 05, 2024, 09:21:59 PM by Scientifiction . »

Offline Chuck Fabo

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Re: “Eclipse MK II”… Dennis Adamisin
« Reply #3 on: December 08, 2024, 03:45:23 PM »
Ty for the links/info!

Offline Chuck Fabo

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Re: “Eclipse MK II”… Dennis Adamisin
« Reply #4 on: March 27, 2025, 03:26:54 PM »
Hello …

@Dennis Adamisin and others … is 2.8 -2.9 Oz in the ballpark for Stab/Elevator, horn, hinges?

Also, built-up wing about 70% completed … do you have a WAG or estimate on weight for this part?

Thanks.

Kind regards, Chuck
 

Offline Gerald Arana

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Re: “Eclipse MK II”… Dennis Adamisin
« Reply #5 on: March 27, 2025, 07:31:56 PM »
Purchased the subject plan yearsssss ago … I desire to build … some questions …

What is an appropriate engine ? (plan states 3.5 Oz. tank)

Changes you would consider/recommend?

Additional thoughts?

Thanks!


Hi Chuck,

 If I were building this ship, I'd move the bulkhead back to the wing LE and make the fuse wider at the TE tapered to the stab. Depending on the wing area, I'd probably use one of my B-40's.

Cheers, Jerry

Offline M Spencer

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Re: “Eclipse MK II”… Dennis Adamisin
« Reply #6 on: March 27, 2025, 09:21:09 PM »
Yea, ya wanna look at the Fuse , hinge to hinge , as a tapered Tourque Box . TORSIONAL stiffness paramount .

the TT 36'd haul it well , perhaps . The GP 44 magnums lighter'n a FP 40 and swings a extra inch a prop . 12 Vs 11 . Ya know its there , or conversely , when it isnt , back on the 40 .


Offline Chuck Fabo

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Re: “Eclipse MK II”… Dennis Adamisin
« Reply #7 on: January 28, 2026, 07:12:56 PM »
Follow-up … about 95% completed … thanks for your input …

Offline Chuck Fabo

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Re: “Eclipse MK II”… Dennis Adamisin
« Reply #8 on: January 28, 2026, 07:14:13 PM »
Pic 2

Offline Chuck Fabo

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Re: “Eclipse MK II”… Dennis Adamisin
« Reply #9 on: January 28, 2026, 07:15:05 PM »
Pic 3

Offline Brett Buck

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Re: “Eclipse MK II”… Dennis Adamisin
« Reply #10 on: January 28, 2026, 08:17:42 PM »
Purchased the subject plan yearsssss ago … I desire to build … some questions …

What is an appropriate engine ? (plan states 3.5 Oz. tank)

Changes you would consider/recommend?

Additional thoughts?

Thanks!

    I think I held the original in my hot little hands long, long ago. I think that was the airplane where Larry Robertson and I were trying to see if his CG had to be inordinately aft (since my similar airplane using the "blended flap" required a ridiculous CG for the time). And Denny's was pretty far aft - and then he pointed out there was a rag on the nose!

    I have an opinion, having built similar models inspired by the first Eclipse, but I would prefer to hear Denny's evaluation.

    Brett

Offline Chuck Fabo

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Re: “Eclipse MK II”… Dennis Adamisin
« Reply #11 on: January 29, 2026, 06:53:31 AM »
Ty Brett …

Will use a Randy Smith Tower 40 as a starter … will seal the hinge lines … hope it performs!? 

Kind regards, Chuck

Offline Dennis Adamisin

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Re: “Eclipse MK II”… Dennis Adamisin
« Reply #12 on: January 29, 2026, 08:57:48 AM »
Chuck:
THANKS for taking on this project.  I/ve only had a few designs published, soothes my EGO on those few occasions I've seen one built!  You made an interesting mod to the top of fuselage & canopy, really changes the aesthetic.. Of course I still think thats the BEST fin/rudder shape in the history of stunt - but I might be a wee bit prejudiced about that...

When I started the high AR airplanes I was fixated on the OS 35S:  it was LIGHT dependable & readily available.  I just could not "drink the kool-aide" on the ST 46.  Seems that everybody flying those needed multiple spares to get through a major meet like the NATs.  However i wanted a comparably big looking airplane still sized to the OS 35S.  High AR offered the promise of higher lift a7 lower drag - nice to have with limited HP of the OS 35S.

MUCH later when I started flying electrics I was able to prove to myself (using battery drain numbers) that the High AR layouts DO result in less power required.  Less power required = MORE power available for maneuvers.  That's a NICE free power-up!

BTW I have had a LOT of people ask if I really used the very thick stabilizer/elevator shown on the plans.  The answer is YES, and to see who I was listening to, check out the Excitation & Imitation designed by Ted Fancher - you may have heard of him,(!!!) turns out he was pretty darned successful: as a Designer, Competitor, Columnist, and all around good-guy!

I see you plan on using a Tower 40.  I have no direct experience with that engine but understand they can run well.  Only concern I can see is that it (or any other suitable engine alternative) is heavier than the OS 35S.  Still, if you use a tongue muffler light weight prop and a plastic spinner you should be able to offset some of the weight penalty.

SEAL THE HINGELINES!  The Ecl-1 is the airplane that demonstrated to me beyond any shadow of doubt that this was FAR more important than any other factor on this  model.  Since learning this I have not built a single airplane (including the RC models I've built) without seals.  Yes I believe its that important.

Looking forward to flight reports!   

    I think I held the original in my hot little hands long, long ago. I think that was the airplane where Larry Robertson and I were trying to see if his CG had to be inordinately aft (since my similar airplane using the "blended flap" required a ridiculous CG for the time). And Denny's was pretty far aft - and then he pointed out there was a rag on the nose!

    I have an opinion, having built similar models inspired by the first Eclipse, but I would prefer to hear Denny's evaluation.

    Brett

Brett:
We still get a chuckle out of this!  And YES, I'd like to hear your opinions!

At that time, I did not intentionally seek out an aft CG location.  I WAS seeking out control ratios that limited control  deflections to a max of 30 degrees using the 4" self-neutralizing bellcrank.  This helped with the THICK surfaces at the hinge lines, the gap at the surfaces could be smaller & less disruptive.  At the time I WAS aware that thicker stab/elevators seemed to be less sensitive to CG - that it allowed a further aft CG without distress.

Biggest un-appreciated "secret" to Eclipse was its long moment arms.  The earlier high AR Orange Crate was designed by then-traditional practice of arranging the surfaces in traditional distances from each other: Nose to wing LE, then tail a normal distance from wing. However: because of the high AR wing AND high AR tail the resulting airplane was very short.  In Eclipse I in essence started with a 48" fuselage side, put the engine at one end and the stab/elevator at the other end.  The wing was located at the "best guess" to achieve balance without resorting to excess ballast at one end or the other.  The result was an 11" nose on an Classic sized airplane.  Because of the swept forward flap hingeline the popular practice of expressing tail moment as hingeline to hingeline is problematic; let's just say its LONG-er than expected.  However, I ALSO believe that the longer tail also makes CG less critical.

Ultimately I think my final CG locations are what result from trimming the airplane to fly comfortably...



Denny Adamisin
Fort Wayne, IN

As I've grown older, I've learned that pleasing everyone is impossible, but pissing everyone off is a piece of cake!

Offline M Spencer

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Re: “Eclipse MK II”… Dennis Adamisin
« Reply #13 on: January 29, 2026, 10:13:55 PM »
The Tower .40 is a FP cone , but ABC . Tower Mufflers half the weight of the OS muffler , its said . So the 11 x 4 two blade or 10 x 4 three blade .  3 1/2 ounce fuel .
If it had a pair of extra holes & a 3/4 prop extension , motor back /4 , it'd be back 3/4 .  %^@

The Big Green Thing , was just porpoiseing , with no muffler .  %^@ maybe . but it didnt . but the C G was ' Aft Max. ' one could say . SO when I threw a Super Tigre
Silent Muffler , which are not the worlds lightest muffler , and it flew way steadier . Untill it broke the 6  A  mounting bolt into the Merco . Intresting thing was it DIDNT
reduce power . on 20 % Nitro .

The Point Being - > the brain cell came up with ' HANDLE SPACING ' . So Not Panicing and trying a few , like 3 & 4 & 3 1/2 inch , to see what happens , then youll know .
Ive found long wings , with the correctish leadout position , resist yaw . So C G & trimmed unyawed , theyre pretty docile . For a Comp ship . IF you fly it .

AS IN , first flight /s  - if the wings tangental - perpendicular blah , square to flight path , youre home . But if its yawed , watch it . Sort that first . Rests less critical.

The Tower should be ace , keep the dirt out & should go forever .  H^^

Wotsi weigh , assembled , everything there .

Offline Chuck Fabo

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Re: “Eclipse MK II”… Dennis Adamisin
« Reply #14 on: February 02, 2026, 06:11:39 PM »
The weight, as is (minus finish coat), = 38.36 oz.

Plus all suggestions, I added a weight box, trim tab, and crossmembers to the top/bottom of fuse.   those long wings/stab are seemly big lever arms.

Again, thanks all for your comments!

Kind regards, chuck


Offline Brett Buck

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Re: “Eclipse MK II”… Dennis Adamisin
« Reply #15 on: February 02, 2026, 10:06:32 PM »
Brett:
We still get a chuckle out of this!  And YES, I'd like to hear your opinions!

At that time, I did not intentionally seek out an aft CG location.  I WAS seeking out control ratios that limited control  deflections to a max of 30 degrees using the 4" self-neutralizing bellcrank.  This helped with the THICK surfaces at the hinge lines, the gap at the surfaces could be smaller & less disruptive.  At the time I WAS aware that thicker stab/elevators seemed to be less sensitive to CG - that it allowed a further aft CG without distress.



    I built a very similar airplane (partially from the Orange Crate, not the fisrt Eclipse) powerred by an ST46, in particular, the "blended" flap. The reason I was checking the CG was that mine ALSO required a radically aft CG to get it to turn. I think it has next to nothing to do with the tail aorfoil or the controls- I think the issue is extreme negative pitching moment. Every airplane I ever built with that sort of airfoil had exactly the same problem. I think the massive discontinuity at the hinge line is the issue.

    My equivalent was only 6:1 , but that, and the techniques of the time, also led to extreme whip-up, just like Ted's completely independent experiment of the same thing (at about the same time). At the contest in question (Detroit early July 83), I was actually flying what amounted to a Genesis 40FSR with a conventional fuselage, ST46, 630 square inches and 44 ounces. I think that was also an ISH contest, and I recall I outscored several Canadian FAI team members, even though I was flying advanced at the time.

   Your dad gave me some great tips on flying in the wind, which kept me from getting blown out of my vertical 8!

     Brett

Offline Dennis Adamisin

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Re: “Eclipse MK II”… Dennis Adamisin
« Reply #16 on: February 03, 2026, 11:17:21 AM »
    I built a very similar airplane (partially from the Orange Crate, not the fisrt Eclipse) powerred by an ST46, in particular, the "blended" flap. The reason I was checking the CG was that mine ALSO required a radically aft CG to get it to turn. I think it has next to nothing to do with the tail aorfoil or the controls- I think the issue is extreme negative pitching moment. Every airplane I ever built with that sort of airfoil had exactly the same problem. I think the massive discontinuity at the hinge line is the issue.

    My equivalent was only 6:1 , but that, and the techniques of the time, also led to extreme whip-up, just like Ted's completely independent experiment of the same thing (at about the same time). At the contest in question (Detroit early July 83), I was actually flying what amounted to a Genesis 40FSR with a conventional fuselage, ST46, 630 square inches and 44 ounces. I think that was also an ISH contest, and I recall I outscored several Canadian FAI team members, even though I was flying advanced at the time.

   Your dad gave me some great tips on flying in the wind, which kept me from getting blown out of my vertical 8!


     Brett

Hi Brett, THANKS for getting back

I mostly agree with your assessment, except instead of pitching moment I attributed the problem with hinge moment, i.e., when blended flaps are deflected there is a big shift in the continuity causing complete separation of airflow over the flap, causing a huge hinge moment (stick force) to overcome.  The separated airflow would also result in a large low pressure zone sucking air through an unsealed hinge gap.  Sealing the gap makes a big improvement BUT the airflow is still separated and creating still-big loads. Aft CG requires less control deflection, making the root problem a bit more manageable - but the separation is still there and still a problem!

Thanks for the shout out for Dad, glad he was able to help you through.
Denny Adamisin
Fort Wayne, IN

As I've grown older, I've learned that pleasing everyone is impossible, but pissing everyone off is a piece of cake!

Offline M Spencer

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Re: “Eclipse MK II”… Dennis Adamisin
« Reply #17 on: February 04, 2026, 10:04:42 PM »
Was either you lot or Rabe ,. that said ( Or was it R. Smith ) , AFT C.G. reduces FLAP HINGE moment . from c.g. , so there . Reduces ' stick load ' .

as an aside  the little 68 inch Mewgulll 8 1/2 + A.R. TWICE in a cutoff loop , fell ion after the air fell off , turning way tight up high . bit of a pig .


The Long Stretched 8:1 green Merco one , was way better . Didnt mind wind . ( Never flew it in turbulent air though . not much . )
way to slow & it was a pig . Correct Airspeed , Like Racing Triangulars on a taut frame . AS a comparison . ( out of 10 . anyway . No Issues on this one .

============================================================================================

asdded . Mightabeen R Powell .

looking at - White Mewgull . Thick wing . rounded L E . Full Span Flaps .
As per ? ? ? ?
Can be a bit like a elevator . C G Forward . nothing much happens but bounce .
C G Aft , flying ' every inch ' its fine . BUT the Air Pushed in tight turns / Slipstream - can CATCH IT . On one wing . ( Hot Air Temp. ) disaster .

The P 38 is a thicker rounder wing than the green M G . flys more like the above . But dosnt get that awful . At All .
Next One'd be 1/2 between it & green M G wing thickness . ( Test Test ) AS ,  despite slight slack on bellcrank output , it flew pretty supported & straight .
at various fields . DESPITE what ill considered observers might relate . an ANALYSIS of intent Vs input has it near spot on . and 2.25 kilo on old OS 35s tells you whats happening .
As its hardly overpowered .

RIGHT . Flap Force Moment . = as the beeg green mewgull had 1/3 rd flap span , the inverse pitch was 1/3rd of the long ones . thereabouts . Some flights on shitty engine runs -
the center of the wing would ' hold it up ' whilst the outers - ussually inner - wobbled / stalled . AT half airspeed in v hard Sq ppullouts .
Corecct Speed - ' Hammering ' tight sq wingover pullouts , 1/2 were clean . Eased , all . Bar Bobble .
as in , these were ' clean ' as often as not .
Consecutive squares the ' groove ' and lack off ' free fall ' it didnt really occur . At All .

Whereas the ' test ' P - 38 was better here . say 50 % more relaxed / less edgey . TESTING tightest available downhill Sq Exits .

-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

These a lot of independant anaylsis of High A R  ' pitch sensitivity ' as in lift increases dramatically with small incidance increases .
A sharper L E holds the seperation point & a broad radius , it shifts with A.o.A. , forming a lifting section .

So - you could work around it - both ways - as a ' line off development .  But id assume broader L E more susceptable to gust disruption IN SPEED / Drag resultant .

The thinkings the P 38s about right . If it were lighter it wouldnt need the excess lift . but w.t.h.

THOUGHT was Mr Adamisin should try chopping his flaps ! .  S?P IF a chap had 1/3rd or 1/2 span interconectable / detachable - from the full span . ( i.e. discconect & lock outer 1/2 off flap , ea side .
ONE could have a direct comparison on a thing or two .

The short M G at full deflection - slow - DEFINATELY act as Air Brakes . The thought airflow deflected = angle opposite tangent at full deflection ( 45 / 50 deg. odd )
D#EFINATELY ' Throw ' the plane upward . Support it . Increase Lift . AT the center - where they are . As thee wing outside that is abit flustered / undecided =

LOOKING at the ' flat plate scenario ' as in . Mega Mushed the uderside is whats holding it up. Rather than airflow over .
https://www.flickr.com/photos/88160313@N03/45947475775/in/photostream/
SX288 in ' overshoot ' mode . (  W F O  get me UP )
https://www.flickr.com/photos/88160313@N03/45947718575/in/photostream/
PS 947 at lowest safe ' full drag ' Power Held .

are fairly illustrative of what Im trying to convey . IF the flaps , on both , continued to the ends off the wing , there might be a problem . In those modes of flight . IF you picture it .

A H A A

Quote
Moreover, by increasing the aspect ratio, the critical angle of attack decreases! This is a negative effect, since the aircraft may stall at a lower angle of attack!!

IF you practise . Flying overweight and or underpowered contraptions , 9 at times ) It gives you oppertunity to explore the outsides off the flight envelope . And outside the flight envelope .
As long as you keep the lines tight .
Which conjures further factors regarding control line manouvres .  Old Chap .
« Last Edit: February 05, 2026, 07:42:35 PM by M Spencer »

Offline Brett Buck

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Re: “Eclipse MK II”… Dennis Adamisin
« Reply #18 on: February 04, 2026, 11:09:06 PM »

Thanks for the shout out for Dad, glad he was able to help you through.

  I miss your dad -he was an *utterly unique* individual, and very helpful to me early on.

   BTW, the entire idea of high aspect ratio airplanes was one I figured would be great given the power limitations of the day, and it worked - as long as the conditions were reasonable. All o fmy earlier designs (including the first) were higher-than-normal.

   I (and many others) found them to be a near-catastrophe in heavy wind using the engines and prop techniques of the time. I persisted with it for quite a while, but as soon as we had unlimited power and power control, I went the other way, and I think that is much superior way to go and much more consistent overall, and far less sensitive to trim.

    Brett

Offline Dave Hull

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Re: “Eclipse MK II”… Dennis Adamisin
« Reply #19 on: February 04, 2026, 11:47:42 PM »
And would the classic Stiletto 660 be considered high aspect ratio by your reconning, Brett?

Offline Brett Buck

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Re: “Eclipse MK II”… Dennis Adamisin
« Reply #20 on: February 05, 2026, 12:04:07 AM »
And would the classic Stiletto 660 be considered high aspect ratio by your reconning, Brett?

  Not particularly.  Denny's first attempt was 7:1, as I recall. But it was a viable idea when we had very limited power.

   Brett

   


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