Blade47

With winter setting in up this way I have turned to my winter project. I would like to put a T tail on my Strikemaster which has been modified with a V tail.

The V tail works well but I just can't leave anything alone

I would like to know about the shape. size, placement and most of all the aliment of the stab to the fuse or engine?

Any other information or flight stores are more than welcome as well.

Thank you ahead of time for any answers.

Cheers

BMatthews

The T tail should be the same size as the normal tail. The stab mounted to the top of the fin generates a lot of loads in the fin and fuselage. So keep the stabilizer and elevator as light as practical and beef up the fin and rear fuselage if it's lightly built now.

For example the Goldberg Sophisticated Lady has a very bad rep for breaking the fin because they tried to put the stab on top of what is pretty much the same fin as the low mounted stab Gentle Lady version.

DocYates

My Feedback: (102)

I have found that the T-tail does react a little differently than the conventional tail. When you go to take off, you want to make sure that you are ready to fly. Th T-tail is blocked a little bit by the wing as the plane rotates. if you are not up to flying speed yet, the tail loses lift for an instant and the airplane will settle back down, and then pick back up suddenly. I constantly had this happen on the VMAR Tomahawk. Once I figured out what was happening I could prevent it by making sure I was traveling a little faster than I normally would on takeoff before rotating.
The same was true on landing. When you flare, the wing will block the effectiveness of the tail and the plane is more likely to just "plop" right back down on the nose. You want you approach to be shallow, with power on, and for your flare to not be excessive. Once you got the hang of it, it was easy. It is very fun to play with and makes it a little challenging. These are just my own observations and may not reflect other's experiences.
Tommy

Blade47

Very good information ...keep it coming.

cheers

hattend

My Feedback: (20)

Pete,

Cut the horizontal stabs off flush with the side of the fuselage so you leave the stab shelf on the inside of the fuselage. Then remove the top sheeting where the vert stab will pass through and epoxy it to the shelf. Put some tri-stock down there on the shelf and you're all set. Then when you re-sheet the top around the stab put a tri-stock shelf on the side of the vertical stab so the new top sheeting will have a nice solid place to rest. The stab is then glued in two separate places and that'll be pretty strong. The back of the Strikemaster doesn't need any more buildup for strength...it's a freakin' baseball bat.

Keep the incidence the same. Use Tri-stock and dowel pins on top to help resist any twisting breakage.

I'll come up with more as the days go by...hahahaha

Don

PS: Obviously you'll have to make the vertical stab height higher so when you drop it down 2-3 inches to the shelf it'll be the same height as the stock configuration. As soon as I get home, I'll scan a drawing I made ...for some reason the work computer doesn't scan anymore since they "upgraded" me on the LAN

Blade47

Right on there Revver Brother #94 had not thought about cutting into the top of the fuse and counter sinking the fin ... good one.

Ed_Moorman

My Feedback: (1)

T tails tend to make rolls into barrels. Not very good for precision.

Getting a good, smooth control set-up without slop is also hard.

Ditto on the strength of the fin.

I have had a few t-tailed planes and right now I have a Sea Monster flying boat with a T tail. It used metal, 90 deg. angle brackets to bolt the stab on. You tend to land a seaplane flat and a little faster so I haven't noticed the blanking of the tail.

BMatthews

I've got two T tail gliders with no flying issues that differentiate from normal tails at all.

BWooster

I scratch built a .25 size t-tail with slotted flaps, on the theory that there would be no pitch up when the flaps deployed, due to downwash. (I had that problem on other airplanes during my flap stage!)

It worked great: the flaps would deploy, the plane would slow right down, and there was virtually no trim change. Unfortunately the plane was a bit heavy, there was no wash out, and an engine failure led to an early demise.

I built a full NACA 0012 airfoiled fin to hold the stab. I bolted the stab to a plywood plate on the top of the fin with nylon bolts. This also made it easy to play with the incidence.

hattend

My Feedback: (20)

Here is a rough sketch. I drew the pushrod in the way you said you were going to do it. I put a pushrod fairing on top to cover up the pushrod hole at the top.

It's really crude since I can't draw but you get the idea.

Don

Blade47

Your Reading my mind again Don! Thats just about what I am going to do for sure .. The stab half that I have will become the Fin and the length when cut to shape and counter sunk will be about 10" to the top 8" + 25% = 10" just like I had planed when I made the V tail lol.

Check out this part number for the control horn I was think of using for the elevator ..SIG Aileron Interconnect Horn ..SIGSH755. If you or anyone else has a better Idea for a control horn let me know

Cheers

hattend

My Feedback: (20)

I would use the same horn as you had in it originally but heat the control horn and rotate it parallel to the connector legs. Solder it back up and you're good to go.

I don't see how using an biplane aileron interconnect would work.

Don

LouW

I am no “T” tail guru, however I have a lot of time as a flight instructor in both Piper Tomahawks, and Beech Skippers, as well as flight test engineering experience with the Lockheed C141, and the C5A. The “T” tail configuration offers little aerodynamic benefit over a conventional tail. The vertical fin and rudder gain a little efficiently since the horizontal tail acts as a tip plate extending their effective span. The effect is not great and is easily negated by the additional structure (weight) required to support the additional flight loads.

One of the reasons to consider the “T” tail on full-scale aircraft is to move the horizontal surfaces out of the wing’s downwash, especially when large flaps are employed. This tends to minimize trim change with flap deployment. Another reason on large transport type aircraft to move the horizontal tail surfaces up is to simplify design of the rear cargo doors for drive on loading.

In the case of the Tomahawk and Skipper, Like the “V” tail on the Bananza, I expect it’s just a matter of wanting a different look (like tail fins on a 1960’s automobile).

There are some definite downsides to the “T” tail. The additional loads and required structure have already been mentioned. The takeoff behavior described is typical of the ones I have flown, but I expect that it is mostly due to the tail being out of the propwash. With a conventional tail, the propwash gives significant elevator authority even when the airplane isn’t moving. However with a “T” tail the airplane must have pretty good speed for the elevator to be effective.

The wing at high angles of attack can blanket the “T” tail. In full-scale aircraft this can result in a “deep stall” from which recovery is not possible. Such aircraft are usually certified with a mechanical stick shaker to give unmistakable warning, and a stick “pusher” to positively prevent control input enough to reach such steep angles. The Tomahawk and Skipper don’t exhibit such a deep stall, however spin recovery is a very exciting ride.

“T” tails look cool and it’s always nice to show up at the field with something out of the ordinary. For normal flying don’t expect great gains in efficiency. Some different characteristics will be seen especially during takeoff and landing. 3D type aerobatics will be most effected since the horizontal will be out of the propwash. This means hovering might not even be possible, and harriers may prove difficult to control. Regular fly through aerobatics won’t be affected as much however knife-edge might require more attention due to the additional roll induced by the high tail. Snap maneuvers probably won’t be as crisp.

The beauty of this hobby is that you can experiment with all kind of stuff for very little cost. Go for it and let us know how it worked.

Blade47

More Pros and Cons ...Good stuff ...this is what I am after..keep it up.

I am about to start the tail mods so will take pictures as it is now and show the work in progress. Using Dons above Master plan as a guide line please feel free to jump in with you suggestions for structure and material to use along the way.

I will get working dimensions to post on the fin/rudder and what i was thinking for the dimension on the stab/elevator and shape.

BWooster

I think another benefit of the T-tail is lower drag. I understand that intersecting planes have high drag (which we minimize with fairings), but T-tails have only 2 intersecting surfaces, versus four on most tail feathers. Another small advantage.

Blade47

Here you go some pics of the T tail I am working on.

ELTIGRE

theoretically the T tail stab can be smaller than the lower placed stab due to the "cleaner " air flow it is subjected to.this makes it more efficient. look at full size airliners to verify. dito on stength of the vertical fin. there have been some full size failures due to the extra loading it apparently puts on the fin. most full size plane only put it there due to issues with engines or for cargo loading/clearance.

Blade47

Work done this weekend ... starting to look like a high wing Tutor.

cheers

multiflyer

LouW mentioned the most important thing to a model flier regarding the T-tail. It is not located in the prop blast.

When we fly a regular single engine model too slow, we can blast out of trouble effectively with power. This is because the instant increased airflow from the prop wash induces significant lift at the wing root and significant control effectiveness at the tail. As we modelers got good at flying we often don’t realize how much this is helping us get out of trouble. We don’t realize how many habits regarding recovery from slow flight, stall, and aborting landings, we form that depend on that prop blast acting on the control surfaces.

This is the big difference that must be learned when prop fliers transition to jets. When a jet gets too slow, blasting the power doesn’t do a thing. Nothing improves until the aircraft actually accelerates to a higher airspeed. Blasting power on a conventional single engine prop plane gives immediate and significant effect. When 3D fliers hover, control effectiveness is purely from prop wash.

Learning to fly a T-tail is similar to learning to fly a model jet. For example, one reaction many learn as skills grow happens during landing. Over flair and balloon results in not so graceful plop onto the runway. This can be fixed by blasting a bit of power just before touching. Prop was produces a little lift at the wing root, but more importantly the blast hits the up deflected elevator and rotates the nose up a bit. This won’t happen with a T-tail.

For stall recovery, a good blast of power while centering the elevator will dig a regular plane out. The prop blast works on the horizontal tail to quickly zero out AOA terminating the stall condition. Slamming power will not yank a T-tail out of deep stall trouble.

I have a memory from a jet meet years ago. This is when jets were just getting working but wheel breaks for landing were not popular yet. Pilots were still landing using prop plane technique of slowing during final so as to arrive at touchdown at minimum speed to avoid rolling off far end of runway. I was standing near a guy landing. At about 300 feet off the end of the runway I heard him say Sh#T. Why? Everything looked fine to me?? Then his jet came in and hit some 10 feet short of the threshold tearing his gear out. Later I asked him what happened. He simply replied he could already see that far away that he had gotten “to far behind the power curve” as the saying goes. Jets (then) need a good 6+ seconds to spool up, then aircraft needs another just about as long to actually accelerate enough to make a difference at the wing and control surfaces. These days they just land hot and slam on the brakes. A T-tail needs similar consideration.

Last, it’s interesting to note that BMatthews mentions above having “two T tail gliders with no flying issues that differentiate from normal tails at all.” The glider has no motor and therefore no prop wash to play on the tail.

Multiflyer

Blade47

All Finished and waiting for spring ... I will heed your words there multifyer and keep the speed up for final... I have been flying prop jets and they have taught me to keep the speed up for final if using a high AOA ...not that one thing has to do with another ..other then speed on final.

cheers

multiflyer

Blade47,

Nice looking model. Looks like a lot of fun. What did you do the finish with? Looks great in the picture.

Multiflyer

Blade47

Why Thank you Multifyer ... the finish is all in Hanger 9 ultra-cote.. the model is a scratch built Strikemaster that was increased in size by 25% and is a very good flier.

multiflyer

How do you like the Ultracote? I have never used it but generally hear it is better than Monokote? I'm interested but couldn't find the Strikemaster anywhere. Do you know who makes or made it? Kit or plans, not ARF, I assume??

Multiflyer

hattend

My Feedback: (20)

Multiflyer,

You can get Strikemaster plans from RCM. Even though the magazine is no longer published, the plans store is still up and operating. Or, you can check the auction sites and find one of the old Midwest kits (they stopped making them in the late 80's)

OR

Get ahold of Blade47 for a set of the Super Strikemaster plans and wood list and then go to this thread

http://www.rcuniverse.com/forum/m_15...tm.htm#1538947

It'll walk you through building one plus it has a list of suppliers for the wing cores and other items.

The big one flies as well as the little one.

Don

multiflyer

Don,

Thanks for the support. Midwest is what I had forgotten. I remember those kits now and ARF version. Turns out a friend of mine has the plans. It will be a ling time before I get to this one. I'm thinking of an even bigger one, and converting to twin or 4 wing mounted engines. That would be different. I have been flying a 4 engine sport plane I designed for many years. It's getting tired and in need of replacement.

Thanks again

Multiflyer