PT-17 Stearman 1.0

[Mzaher]

Just curious, those of you that have built this. How much weight are you putting in the nose to get this to balance? Even with a PLA-printed radial, I've added close to 2 ounces.

 

[wilmracer]

Just curious, those of you that have built this. How much weight are you putting in the nose to get this to balance? Even with a PLA-printed radial, I've added close to 2 ounces.

That doesn't sound bad TBH. I don't recall how much weight was needed on the stock build but I haven't done a standard size with a printed radial. What is your AUW? This model has plenty of wing area and the "stock" build is pretty light. At 32oz the cube loading is on the low end of trainers and park flyers. You'd have to add close to 12oz to even push the loading into the sport category.

 

[Mzaher]

Just picked up a scale today. Guess I'm in the ballpark, AUW is 940g, just over 33oz. So I should be in good shape. Thanks for your feedback.

 

[wilmracer]

Just picked up a scale today. Guess I'm in the ballpark, AUW is 940g, just over 33oz. So I should be in good shape. Thanks for your feedback.

Thanks! That's great to hear that your AUW is right inline with what we've seen. Always good to have independent confirmation from the community. She will fly great at that weight.

 

[Yankee2003]

Thanks! That's great to hear that your AUW is right inline with what we've seen. Always good to have independent confirmation from the community. She will fly great at that weight.

I have a question on mounting the motor. The power pod slides in and can fit up against the airframe firewall. But it seems like it will have an upward thrust angle. Or am I just seeing things?
What was done, if anything to the motor thrust angle? I want to say that the thrust angle needs to be incorporated on the power pod motor mount Prior to sliding it into the fuselage. But I don’t really know.

 

[Mzaher]

I have a question on mounting the motor. The power pod slides in and can fit up against the airframe firewall. But it seems like it will have an upward thrust angle. Or am I just seeing things?
What was done, if anything to the motor thrust angle? I want to say that the thrust angle needs to be incorporated on the power pod motor mount Prior to sliding it into the fuselage. But I don’t really know.

Check to make sure your firewall is on the correct end of the power pod, mine appears to have a couple degrees right and down thrust on it. A close look at the plans, you can see a slight angle cut on one end. If by chance you cut it straight across you will only get right thrust.

 

[Yankee2003]

Check to make sure your firewall is on the correct end of the power pod, mine appears to have a couple degrees right and down thrust on it. A close look at the plans, you can see a slight angle cut on one end. If by chance you cut it straight across you will only get right thrust.

Okay. I see the arrow pointing forward. So just slide it in up against the airframe firewall and all done? No shims, Bob’s your uncle, and all that?

 

[Mzaher]

Okay. I see the arrow pointing forward. So just slide it in up against the airframe firewall and all done? No shims, Bob’s your uncle, and all that?

Correct, the "A" fold symbol faces forward and is the indicator for where to attach the firewall. This is a typical Flite Test building practice.

 

[Yankee2003]

Correct, the "A" fold symbol faces forward and is the indicator for where to attach the firewall. This is a typical Flite Test building practice.

Thank you.

 

[wilmracer]

@Yankee2003 Yeah, my experience with the larger versions indicated that you really want that down and right thrust. I was a bit over-powered on my 175% version but on the maiden flight it took all the down trim I had to get it flying level-ish and when I came off the throttle it nosed down hard. For the 200% version I'm starting with a fair amount and I'm making sure I can adjust easily.

 

[Mzaher]

Yeah... To all building to Ben's plans, don't be shy with the down trust!!! Maidened mine today and it ate up almost all my down trim. You can see in the picture there is a reasonable amount from the stock build. Y'all might want to consider trimming a little more angle to the fuselage supports for the power pod to get more down or add a millimeter to the top side of the power pod? I'll be figuring out how to get a washer in on the top side of my motor mount or even just cut a new power pod with more angle. And if that doesn't work, just make a mix, as the throttle goes up, the elevator goes down. Other than that she flew pretty nice, very responsive to the ailerons, and will be backing off the travel on those a bit for the next couple of flights. The maiden was with Flite Test's "B" motor 3s and a 10x4.5 prop.

 

[wilmracer]

Yeah... To all building to Ben's plans, don't be shy with the down trust!!! Maidened mine today and it ate up almost all my down trim. You can see in the picture there is a reasonable amount from the stock build. Y'all might want to consider trimming a little more angle to the fuselage supports for the power pod to get more down or add a millimeter to the top side of the power pod? I'll be figuring out how to get a washer in on the top side of my motor mount or even just cut a new power pod with more angle. And if that doesn't work, just make a mix, as the throttle goes up, the elevator goes down. Other than that she flew pretty nice, very responsive to the ailerons, and will be backing off the travel on those a bit for the next couple of flights. The maiden was with Flite Test's "B" motor 3s and a 10x4.5 prop.

Great to hear she's had her maiden! Congratulations! Looking forward to seeing it at FF!

 

[Yankee2003]

Yeah... To all building to Ben's plans, don't be shy with the down trust!!! Maidened mine today and it ate up almost all my down trim. You can see in the picture there is a reasonable amount from the stock build. Y'all might want to consider trimming a little more angle to the fuselage supports for the power pod to get more down or add a millimeter to the top side of the power pod? I'll be figuring out how to get a washer in on the top side of my motor mount or even just cut a new power pod with more angle. And if that doesn't work, just make a mix, as the throttle goes up, the elevator goes down. Other than that she flew pretty nice, very responsive to the ailerons, and will be backing off the travel on those a bit for the next couple of flights. The maiden was with Flite Test's "B" motor 3s and a 10x4.5 prop.

Literally just glued it in yesterday with the fake motor ring. 😒. I wonder if making it a bit nose heavy might work to counter balance the thrust angle. Shifting the CG….do either of these ideas have any merit?

 

[Mzaher]

No clue about that one Yankee, someone will probably chime in on that. I did some digging yesterday about down thrust, finding that the wing incidence angle could also be a factor. So I'm thinking that depending on how the top wing sets on the struts and cabane's could affect that angle requiring different thrust angles? And too much down thrust causes other flight characteristics problems. Guessing each build could be different. On mine I'm going to try 1, 3mm washer on top, and see what happens. From there I'll just make a throttle curve mix with the elevator. Maybe some building guru out there will come up with a jig to set the incidence angle during assembly.

 

[Yankee2003]

No clue about that one Yankee, someone will probably chime in on that. I did some digging yesterday about down thrust, finding that the wing incidence angle could also be a factor. So I'm thinking that depending on how the top wing sets on the struts and cabane's could affect that angle requiring different thrust angles? And too much down thrust causes other flight characteristics problems. Guessing each build could be different. On mine I'm going to try 1, 3mm washer on top, and see what happens. From there I'll just make a throttle curve mix with the elevator. Maybe some building guru out there will come up with a jig to set the incidence angle during assembly.

Thank brother. I am thinking…a bit nose heavy…sub trim down elevator to keep more available trim and plan on a faster, steeper, power on landing approach to maintain control.
On the bright side….it should do better inverted. Something that will help on the ribbon cutting (assuming it survives the barn door).
Depending on how close to FF I finish it, I might not chance a maiden before the meet and greet.
Maybe I could start a spare..🤔…..God help! That never entered my mind until this minute…..no….no…I won’t do it……..probably.

 

[Yankee2003]

Thank brother. I am thinking…a bit nose heavy…sub trim down elevator to keep more available trim and plan on a faster, steeper, power on landing approach to maintain control.
On the bright side….it should do better inverted. Something that will help on the ribbon cutting (assuming it survives the barn door).
Depending on how close to FF I finish it, I might not chance a maiden before the meet and greet.
Maybe I could start a spare..🤔…..God help! That never entered my mind until this minute…..no….no…I won’t do it……..probably.

Okay….just one rattle can…spray it all white and write spare on it…🤔
I can always let someone else pilot it if I have a bit of luck.

 

[wilmracer]

If you're trimmed for level flight do you notice a sudden pitching down when you cut throttle? I wouldn't expect that behavior if the issue was incidence related (but maybe someone with an aerospace degree could chime in @Mid7night ).

 

[Mzaher]

If you're trimmed for level flight do you notice a sudden pitching down when you cut throttle? I wouldn't expect that behavior if the issue was incidence related (but maybe someone with an aerospace degree could chime in @Mid7night ).

I'll have to get back to you on that. I'm a relatively new part-time pilot, this will be my third summer. So I was focused on trying to keep it out of the clouds. LOL. If the local weather holds up for tomorrow I might get to fly again, I'll pay more attention if she drops. And if one of the more experienced club pilots is there, some conversation will be had.

 

[Mid7night]

General note: Yes it probably needs a degree or two of downthrust. I have a nice hunk of lead that lives in my nose ahead of the battery. 🤣

I don’t think the motor-pod has any angle built into it. Probably worth a release-revision. (Sorry @SP0NZ ) 😜

In the meantime, put a washer or two behind the top motor-mount-screws or trim the end of the motor-pod accordingly before gluing the firewall on.

Sorry for missing that guys!

 

[Yankee2003]

General note: Yes it probably needs a degree or two of downthrust. I have a nice hunk of lead that lives in my nose ahead of the battery. 🤣

I don’t think the motor-pod has any angle built into it. Probably worth a release-revision. (Sorry @SP0NZ ) 😜

In the meantime, put a washer or two behind the top motor-mount-screws or trim the end of the motor-pod accordingly before gluing the firewall on.

Sorry for missing that guys!

Time to cut the false motor off. Should be an easy fix at this point. Thanks for the information Ben.
The plane does look great, nice design.