PA-38

Tom-D

Tom-D

Taxi to Parking
Joined
Feb 23, 2005
Messages
34,740
Display Name
Display name:
Tom-D
any one know of engine up grades for the PA 38 beyond the 125 horse 0-235?

is there one to use the 0-320?
 
"I did all of this under an STC Application but stopped when the FAA told me I had to do spin testing. I wanted to placard it 'No Spins' but that was not acceptable to them. I would of had to mount a spin chute and a quick release door for their pilot to test fly it and I didn't want to go thru all of that. So I filed a Form 337 to cover the changes and dropped the STC. I never did spin it but I'm sure it would of had a much better recovery."

http://pipertomahawk.com/320install.htm
 
zaitcev said:
"I did all of this under an STC Application but stopped when the FAA told me I had to do spin testing. I wanted to placard it 'No Spins' but that was not acceptable to them. I would of had to mount a spin chute and a quick release door for their pilot to test fly it and I didn't want to go thru all of that. So I filed a Form 337 to cover the changes and dropped the STC. I never did spin it but I'm sure it would of had a much better recovery."

http://pipertomahawk.com/320install.htm
Click to expand...

I see the aircraft got destroyed want to tell us about that?

do you still have the data file?
 
It was many years between flights in a 152 and a Tomahawk, but I don't remember the Tomahawk as being that under powered, relative to the 152.

Do Tomahawks need more power?
 
I thought the "traumahawk" was already placarded against spins.
 
JoseCuervo said:
It was many years between flights in a 152 and a Tomahawk, but I don't remember the Tomahawk as being that under powered, relative to the 152.

Do Tomahawks need more power?
Click to expand...

The plane was designed as a trainer. Unless you're at a high/hot airport, the 112 HP 0-235 is just fine for that role - it doesn't burn a lot of fuel, and the airplane performs fine. But, if you want more climb or a little more speed, you'll need more ponies under the cowling.
 
JoseCuervo said:
It was many years between flights in a 152 and a Tomahawk, but I don't remember the Tomahawk as being that under powered, relative to the 152.

Do Tomahawks need more power?
Click to expand...

Everything needs more power! :D
 
ah....the Traumahawk. I remember it well from my spin training as part of the Canadian PTS for the PPL. We only needed to do incipients; the Traumahawk showed me what full spins were like.
 
JoseCuervo said:
Do Tomahawks need more power?
Click to expand...

I think the idea is to try to make a certified RV-9 or something. It's been tried before with the Grumman Yankee, the Globe Swift and the Cessna 152. Short on gas and short on useful load. Wanna go fast? Gotta start from scratch.
 
kyleb said:
The plane was designed as a trainer. Unless you're at a high/hot airport, the 112 HP 0-235 is just fine for that role - it doesn't burn a lot of fuel, and the airplane performs fine. But, if you want more climb or a little more speed, you'll need more ponies under the cowling.
Click to expand...


As I remember, it was a bit more comfortable than a 150. Two grown men could sit side by side a bit more comfortable than a 150.
 
Dav8or said:
I think the idea is to try to make a certified RV-9 or something. It's been tried before with the Grumman Yankee, the Globe Swift and the Cessna 152. Short on gas and short on useful load. Wanna go fast? Gotta start from scratch.
Click to expand...
This isn't about going fast.
 
why is it? that every time we talk about upgrading the horse power folks here think we are trying to go faster?
Faster is a profile drag issue not horse power.
 
Tom-D said:
why is it? that every time we talk about upgrading the horse power folks here think we are trying to go faster?
Faster is a profile drag issue not horse power.
Click to expand...

Because it is about going faster. Horse power is commonly used to overcome profile drag. Either climbing faster, cruising faster, or both. Rarely do these engine swaps get a significant increase in gross weight, so it's not about hauling more and they never get much of an increase in fuel tanks, so it's not about flying farther. Bigger engine rarely ever means flying cheaper. So why, if not to go faster, would you want an O-320 in a Tomahawk?
 
Dav8or said:
So why, if not to go faster, would you want an O-320 in a Tomahawk?
Click to expand...

Well, an O-320 would be overkill in a Traumahawk. But to answer your question otherwise, takeoff and climb performance. I fly a Cessna 150 with an O-320 in it. We use it to tow gliders.

And to sort of rephrase what Tom said, it takes a SIGNIFICANT increase in horsepower to make any appreciable change in cruise speed.
 
Dav8or said:
I think the idea is to try to make a certified RV-9 or something. It's been tried before with the Grumman Yankee, the Globe Swift and the Cessna 152. Short on gas and short on useful load. Wanna go fast? Gotta start from scratch.
Click to expand...

Works well with a Swift. I wouldn't put it in the same category as a 152 or Yankee.

The one in my avatar is a 180HP Lyc IO-360

590lb useful load, older garmin gps stack and radio/tx. IFR certified. 59 gallons fuel capacity. We leave it filled to 35 gallons, there are two 12gal auxilary wing tanks if you need the extra range.

An similarly equipped RV-6 has about 15kts on the Swift, maybe a little more. It does well for a 68 year old airplane though. I think a good part of the speed discrepancy between the two aircraft is parasite drag from construction methods. A swift with flush riveted wings and a bubble canopy will pick up another 10 knots.
 
Last edited:
Greg Bockelman said:
Well, an O-320 would be overkill in a Traumahawk. But to answer your question otherwise, takeoff and climb performance. I fly a Cessna 150 with an O-320 in it. We use it to tow gliders.

And to sort of rephrase what Tom said, it takes a SIGNIFICANT increase in horsepower to make any appreciable change in cruise speed.
Click to expand...

I was asked if the 0-320 was feasible, knowing that the FAA will approve the upgrade quicker when there are other copies flying than doing the one time STC.

I was looking for some one who had completed this process and has the data to do it. The why do it issue is none of my business the customer wants it, is good enough for me.
 
Greg Bockelman said:
Well, an O-320 would be overkill in a Traumahawk. But to answer your question otherwise, takeoff and climb performance.
Click to expand...

Climb performance. As in to climb faster. Take off performance. As in to reach rotation speed faster. It is about going faster.
 
Tom-D said:
I was asked if the 0-320 was feasible, knowing that the FAA will approve the upgrade quicker when there are other copies flying than doing the one time STC.

I was looking for some one who had completed this process and has the data to do it. The why do it issue is none of my business the customer wants it, is good enough for me.
Click to expand...

Understood. Seems really dumb to do considering that with the money he will spend to have you engineer a solution, buy the new engine, test fly the plane and do battle withe the FAA, he could have just sold the Tommy and bought a used RV-9 and had a better plane in many ways.
 
Dav8or said:
Because it is about going faster. Horse power is commonly used to overcome profile drag. Either climbing faster, cruising faster, or both. Rarely do these engine swaps get a significant increase in gross weight, so it's not about hauling more and they never get much of an increase in fuel tanks, so it's not about flying farther. Bigger engine rarely ever means flying cheaper. So why, if not to go faster, would you want an O-320 in a Tomahawk?
Click to expand...

Fat ass, high altitude, short strip with high trees...
 
Henning said:
Fat ass, high altitude, short strip with high trees...
Click to expand...
Not much of that applies in this case we are at sea level, he's not fat, and has no big trees at the end of his strip. but it is short.
 
I know it doesn't not apply here but as a 172 owner with a 145 HP engine I keep thinking about how to get more power for density altitude for places I want to go. That was the first though in my head reading this.
 
Luvrv8 said:
I know it doesn't not apply here but as a 172 owner with a 145 HP engine I keep thinking about how to get more power for density altitude for places I want to go. That was the first though in my head reading this.
Click to expand...

Put a turbo on it.
 
Luvrv8 said:
I know it doesn't not apply here but as a 172 owner with a 145 HP engine I keep thinking about how to get more power for density altitude for places I want to go. That was the first though in my head reading this.
Click to expand...

There are several STC up grades for the 172 including the 220 horse franklin.
 
Tom-D said:
it's not that easy.
Click to expand...

Physically or paperwork? Physically it's simple, paperwork wise, Jack Riley seemed to have had it figured out, he put turbos on everything. Heck, there used to be a C-150 at Leadville that had a turbo.
 
It might be easier to "hotrod" the existing engine, than to install an O320.
Shouldn't be too hard to eek 125-130 hp out of the O235 that's in it.

I would think that adding an O320 would mabe increase takeoff/climb performance, but at what cost?

The Yankee we had came to us with the O320 stc. (not installed, and I now know why) When it came time for at least a top oh, I sat down and read the STC. Pretty much you suspend the engine, and re-build the airplane around it. The only GW increase is for an extra fuel tank behind the seat. So we went looking for a runout O235 with a decent top end. Guess what, the Yankee uses a rare version, and there just isn't any that are not already installed in Yankees.
The guy who bought it, wanted it because it came with the STC, and he had an O320 on the shelf. We didn't tell him that he'd have to buy a Cheetah to get the rest of the parts needed to install the STC. ;)
 
bluerooster said:
It might be easier to "hotrod" the existing engine, than to install an O320.
Shouldn't be too hard to eek 125-130 hp out of the O235 that's in it.
Click to expand...

The Sparrowhawk conversion raises the compression ratio and nets 125 hp. That conversion is STC'd on the Tomahawk.

Apparently, Tom's customer wants more...
 
Hang an LS-7 Chevy on it, apply for an STC and operate it ExR&D and let him fly it. There's a Twin Commander still flying around on Orendas like that for over 2 decades with no limitations other than the general Experimental limitations. A Tomahawk with 400hp should get out pretty short, put a Lenco 2 speed on it for reduction and now you can have 650hp for takeoff; should be airborne before the hangar door.
 
Last edited:
Henning said:
Hang an LS-7 Chevy on it, apply for an STC and operate it ExR&D and let him fly it. There's a Twin Commander still flying around on Orendas like that for over 2 decades with no limitations other than the general Experimental limitations. A Tomahawk with 400hp should get out pretty short, put a Lenco 2 speed on it for reduction and now you can have 650hp for takeoff; should be airborne before the hangar door.
Click to expand...

there ya go again, over the top of reality.
 
Years ago, I considered buying a Tomahawk and did the research. It doesn't seem there are hardly any STCs for the plane. Only the Sparrowhawk engine mod. Not even wheel pants and you would think somebody would try to make it go faster. This told me that the people that own Tommys aren't really all that passionate about them and really don't want to put any money in them. I doubt anybody has ever put an O-320 in one before. I doubt there would be anyone beyond your client that would ever want to pay for it.
 
Dav8or said:
I doubt there would be anyone beyond your client that would ever want to pay for it.
Click to expand...

I did give him a gustamate and haven't heard back.
 
You must log in or register to reply here.
Back
Top