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Aug 07, 2003, 12:48 PM
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Ralph A. D'Amelio's Avatar

T-28 Trojan


Always like this plane . I believe Dave Platt did a super detail rendition many yrs ago. I have scaled up the Guillows T-28 to 32" and 48" ws. Smaller one be nice for a 400 size outrunner
and the 48" size for an AXI 2820/10 o 8 or 10 cells .

My questions: 1)as anyone done a T-28.

2) the wing incidence on the Guillows is set at a relatively high positive AOA (3-5degrees) the horz tail is also set positive but does not appear to be the same. Should this be kept or was it done srictly for the Guillows rubber powered model

Thanks Ralph.
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Aug 08, 2003, 03:40 AM
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vintage1's Avatar
Ralph: From what I can remeber of rubber models, they area always very low wing loading, flying at quite high angles of attack and had a lot of inbuilt stability - decalage. If you are going for control you don't need that decalage for a start, and if teh wing loading goes up, so will your natural flying speed, and teh angle of incidence will need to come down.

i.e. you will be flying the wing faster at lower angle of attack. If you leave the rigging incidence positive, the model will tend to have to fly nose-down to compensate.

It will fly OK, but with higher profile drag off the fuselage, and with a slightly strange look.

I'd go for almost zero on rigging angle on the tailpane and about 1-3 on the main wing, and if possible make the main wing adjustable.
Aug 08, 2003, 04:02 AM
Big gov never Works
St. Martin's Avatar
Hi Ralph,

I posted on this thread last nite, it disapeared...

Try it again..

I built two Pica T-28's. One thing to notice is the full-size had gob's of down thrust already. This is not present in the Guillows because of the rear peg position. So they had to do it another way, with the wing & stab.

I have enlarged the Guillows for I.C. use before. 200% like yours.
I left mine stock on the stab, and reduced the pos. in the wing. put in scale down thrust. I often thought about another, now that I'm using "E". I will use the down thrust, and 0-0 on the wing & stab next time.

Steve
Aug 08, 2003, 05:34 AM
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vintage1's Avatar
Thats a curious thought. I had always reckoned that what counted with downthrust was the relationship of teh thrustline to the center of drag.

I don't see that thrustline to incidence makes a huge amount of difference, except that with the plane flying a bit nose down, it may have some effect. Not in terms of pitching teh nose down as you want as much as just dragging the whole plane down.
Aug 08, 2003, 07:23 AM
Big gov never Works
St. Martin's Avatar
I dragged out my incomplete Pica trojan. there is aprox 2deg. pos in wing, 2deg washout. Stab looks 0deg. Mtr is 2-4deg down.
And 2deg right.

I was also loking at a Gus Morfis Hellcat I built. Same set-up.
The wings pos. is negated by the wash-out. The airfoil is semi-symetrical/lifting, hence the need for down thrust for high thrtl applications. The Hell cat has sim. proportions to the Trojan, also in the use of lots of down thrust.
It' really a balancing game between incidences, thrust lines and airspeeds to accomplish a more level attitude approach to landings. This required for students, and carrier service.

Why the T-28 did not have a more conventional set-up, was visibility over the cowl, and slow flight capability on landing without excessive nose high attitude.
The down thrust also helped in aborted landings, to avoid the power on stall. (Bolter)
The guillow's T-28 flew very well a reduced thrt. But, required up elev trim at higher power.

Steve
Aug 08, 2003, 02:37 PM
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PaulBrad's Avatar
While this may not quite be what you had in mind, way back in the early days of the Ezone I had a construction article for a profile Speed 400 T-28 published. You will find the article at http://rcgroups.com/links/index.php?...t=202&id=3503. If you are willing to go with a profile scale model, this T-28 has proven to be a fun sport flyer. The new power systems could really make it go.

Paul Bradley
Aug 08, 2003, 05:03 PM
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vintage1's Avatar
If you have a computer TX, adding in down elevator and right rudder/aileron on throttle works really well.

And avoids props hanging at odd angles. I used this on teh Sperry monoplane and it tracks really well now.

Actually, its my current best flying plane, since most of teh others got busted up this last week
Aug 08, 2003, 05:16 PM
EB-66C Team Member
J Morgan's Avatar
Ralph,
Dave Rees has a rubber plan about 27" or so that you could scale to what you want. His stuff is great and flies great. His company is HiLine, small electrics.
Aug 08, 2003, 05:44 PM
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Ralph A. D'Amelio's Avatar
Wow thanks all. I thought for a moment no one was going to answer. Isn't it funny we seem to get use to instant answers and graification

I need to digest want you all said but it looks like I will build as I normally would 0-0 wing /elev and 2 down and right. As Vintage1 says I can trim electronically.

I always admired the PICA T-28 and but never got around to building one. Do they still exist as a kit and how heavy is it?
Aug 08, 2003, 05:45 PM
Registered User
Ralph A. D'Amelio's Avatar
PS I think I will play around with a 32" or 200% with my MPI 25/35 bl. Then consider a 45 " ws for winter building.
Aug 08, 2003, 05:59 PM
Big gov never Works
St. Martin's Avatar
With a .91FS, flaps, retracts(RHOM), Vortac bomb release.
Finish was glass & Perfect Paint, 11-1/2#. 1/6 scale

I'm at that point in construction on #2 that I can go electric. But, what a cost? I guess one of the Megas and MEC drive would be sufficient. Never did an E plane that big. Need more experience.
Besides I like the small stuff better..

Steve
Aug 08, 2003, 08:02 PM
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Ralph A. D'Amelio's Avatar
Sounds awesome.
Aug 09, 2003, 07:30 PM
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Bradley Profile Speed 400 T-28


I bought this plan about 3 years ago but haven't built it. Does E Zone still sell plans? I haven't been able to find the plans page recently.


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