Thorp Air Command - T18.net

I've read that the Thorp canopy has positive pressure holding the canopy closed while in flight. This is very reassuring to passengers who are not familiar with flying in small planes and whos worst fear is to "fall out" of the plane. it is also very nice in that the canopy latch does not have to be some critial and super strong item where the whole stress of the force of the canopy is being held back by the latch.

However....

My question is how much pressure is holding it closed? Is it easily overcome if a person had to bail out with a parachute if something major went wrong doing aerobatics or something?

My thought was that in order to legally do aerobatics, one must wear a parachute. However if the canopy cannot be opened in flight, then what good would a parachute be if you can't get out of the plane?

One thing that I dont' particularly like is that the canopy doesn't seem to open very wide for entry/exit. Has anyone done anythingt to try to make this gap a couple inches wider? In order to make it just that much easier to enter/exit. This narrowness I would imagine would be far worse if a person had a parachute strapped to them and was in a panic trying to bail out ASAP!

I would hate to have to attempt to "bail out" and have the canopy continuiously trying to keep closing upon me like a jaw of a dragon trying to chew me up while I was trying to get out!

Am I making a mountain out of a mole hill or what?

Some of us would say that "yes, you are making a mountain out of a mole hill". The T-18 design is over 50 years old, & this subject has been discussed in detail many times. You seem to be really interested in re-designing the Thorp. In my personal opinion, depending on how violent the situation is and unless you're a young, really flexible guy you probably haven't got a snowball's chance in hell of getting out in time, even if you could jettison the canopy.

BTW, it is not illegal to do aerobatics without a chute if you're by yourself.

On second thought, my comments above may seem a little harsh, Tom... I don't mean them that way.

_________________
John Evens
Arvada, Colorado
T-18 N71JE (sold)
Kitfox 7 SS N27JE

Maybe an ejection seat, that would make rich feel right at home and a couple of other thorp drivers... Maybe you never know.

Lance

I don't want to re-design the plane. I've asked a few questions and I think I've prefaced most of them admitting that I'm a newbie. I have read almost every post on this forum. And after reading all of those posts. I have not read a single one that discussed bailing out of the aircraft or having the canopy open up wider. So I thought I was safe to bring the question up. I will admit that I have only just gotten through the first 16 of the archived news Letters. And there are well over 100 NL's, so forgive me if I have not yet learned and committed to memory 50+ years worth of information as yet.

As far as re-dseigning, it seems to me that the S-18 was a pretty significant design change/evolution from the original T-18, and some (me included) would argue that they were improvements or at least desireable enhancements. Are you saying that the S-18 is now perfect and no further enhancements can or could be made to make it better or more convenient? I was thinking that this forum was a place to come up with possible thoughts on enhancements etc. I'm sorry if I stepped on anyones toes for even asking if someone had thought of an idea before. I guess I never knew a perfect airplane was ever designed. I guess I know better now!

It is just that the "thickness" and "width" of at least the average American has increased considerably over the last 50+ years. I'm not too large myself, but it just seems that the canopy opening width just seems tighter than would be convenient in todays world. I suspect opening up the width more must be difficult due to the length of the rails and the shape of the fuselage that would make it difficult to have the canopy slide further aft. A couple of inches would be a pretty significant percentage and would seem would considerable aid entry/exit.

How's this for a re-design? What about a tab or some sort of latch that would hold the canopy in the full open position. At least then it wouldn't want to shut itself if you forced it open to get out. Opps!!!! There I go again changing a perfect airplane.

I am not aware of anyone making a canopy that opens wider. Maybe when you start building your Thorp and get to that stage in the process, you could incorporate it into the build. If you would redesign it, I'm sure everyone here would be interested to see how you did it.
Builders have certainly personalized their planes with very worthwhile improvements which others used in their projects. If you are the first to do a particular redesign, you get the exciting and well paid job of being the test pilot!
As far a jettisonable canopy, it might work to use a ball pin instead of bolts for the two front roller bearings on the side canopy tracks. In an emergency you would need to unlatch the canopy, pull two pins and push up on canopy. Pins would intrude on interior space and snag you in the shoulder every time you open canopy tho and you might not want one to fall out by accident in everyday use.

Bernie
N18xs

I've never owned a parachute.....prolly never will....and I would never, ever go beyond 60/20 with a passenger in the plane........that would be against the uh....rools. I once tried to open the door of a C-172 after realizing I didn't latch it properly. I began to eat wheaties after that. I spose if I had to get out of my plane, I'd have to go hammerhead and time it correctly.........but then again......without a chute!.

_________________
Fraser MacPhee
N926WM
Serial #279-1
Angel Fire, NM (KAXX)

Tom,
Please don't take comments here personally. We love our Thorps, both S and T variety. I should think that if it is important to you, you could design a way to get rid of the canopy. The mentioned mod was something I've considered. How far it will open in flight depends on pressure which is directly related to airspeed. If you muff a maneuver, you will either be in a spin, or zooming at the earth. I'm guessing the spin would allow you to open it sufficiently. That's a guess. I've only tried to open it in level flight. It doesn't open very far at 100kts. Also, consider that you are spoiling the airflow with the canopy open. Never, ever try to fly a Thorp without the canopy installed. It is just about not controllable.
Cubes

I think it would be great to have a few more inches of opening to get in and out. I doubt very much if a pilot could ever get out of a T-18 with a parachute on in uncontrolled flight. Years ago when I was getting ready to deliver my T-18 to a paint shop I thought it would be a good idea to remove the canopy from the frame, reinstall the frame and deliver the plane so there would be no masking of the plexiglass. I removed the canopy and flew (if you could call it that) the plane. It was just barely controllable at any speed!!! I made a very gentle turn of about three miles radius and managed to get it on the ground in one piece. As my old and wise fathers expression so vividly describes, it shook like a dog s------ peach sends.