• This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn more.

FTFC'18 WWII Curtiss-Wright XP-55 Ascender

LitterBug

Troll Spammer
#21
Looks like you were real close to the last remaining XP-55 example on your trip. It looks like it is in a museum in south west Michigan. Going to be up in that area over Labor Day weekend, and may try to convince the fam to head over and get some pics.

Cheers!
LitterBug
 

HilldaFlyer

Well-known member
#22
That's a nice looking plan!

But that load of huckleberries looks way better! :applause:
For sure!! We made 5 quarts of jam so they would survive the four day trip back. Yummy. Your syrups were great... but, hey, when it comes to taste, I don't think there are many things on earth that match the taste huckleberries. Just a side note - local businesses were paying $55/gallon for the berries to put into their ice cream, and various other commodities.
 

HilldaFlyer

Well-known member
#23
Looks like you were real close to the last remaining XP-55 example on your trip. It looks like it is in a museum in south west Michigan. Going to be up in that area over Labor Day weekend, and may try to convince the fam to head over and get some pics.

Cheers!
LitterBug
Funny - I didn't know much about the history of the XP-55 until last night when I read up on it and added the write up to the first post. Had I known, I probably would have swung by to see the only XP-55 in existence which is on exhibit at the Air Zoo Museum in Kalamazoo Michigan - darn it, was only a 20 mile detour which would have been shorter than the interstate closure in ID Falls.
 

flitetest

Administrator
Admin
#24
Hey guys!
David!- Loved looking at the pictures from your ROADTRIP ;) It is always a blessing to be able to see into the lives of the community from a DIFFERENT perspective then just planes sometimes! ha Thanks for sharing and good luck on the building!!
Blessings,
Stefan
 

HilldaFlyer

Well-known member
#25
Just a heads up, but the shinden would not hardly fly at all without a functional canard. If you turn it off mid flight, the plane would still fly, but you would't have enough elevator authority to do much more than keep the plane level.
Hi Localfeind, On your Shinden... did the entire canard surface rotate or only a portion like a typical control surface on the trailing edge? The reason for the question is design efficiency. The real XP-55's canard (maybe I should start calling it the forward elevator) rotated. Trying to come up with a simple design to make the whole thing rotate.
 

HilldaFlyer

Well-known member
#26
Hey guys!
David!- Loved looking at the pictures from your ROADTRIP ;) It is always a blessing to be able to see into the lives of the community from a DIFFERENT perspective then just planes sometimes! ha Thanks for sharing and good luck on the building!!
Blessings,
Stefan
Glad you enjoyed it... and I hope others did too. For a second there, I was going to apologize for sidetracking my own thread, but then I realized it was MY thread. :p
 

Fluburtur

Cardboard Boy
#27
I saw a jet Rafale last year, the canards where linked by a simple wooden rod on what I would call the "aerodynamic balance point" and only rotated by a simple servo, I think this would be rather easy to do. You just need to find out where to put the pivot point.
 

Fidget

Active member
#29
I saw a jet Rafale last year, the canards where linked by a simple wooden rod on what I would call the "aerodynamic balance point" and only rotated by a simple servo, I think this would be rather easy to do. You just need to find out where to put the pivot point.
That's how Steve Shumate did the elevators for his T-38:
https://www.rcgroups.com/forums/showthread.php?306817-T-38-Talon-Park-Jet

Picture1.png

I made a DTFB version and used a BBQ skewer with a servo horn shoved over it. One could do better but it was what I knew how to do. I think Kevin Matusik uses a 3/16" dowel rod for that on his Raiden.
 

rockyboy

Skill Collector
Mentor
#30
Foey! I was gonna do an XP-55! now I have to find something even more unusual! Best of luck to you, I can't wait to see your project grow.:D
Come on in if you want - you could make one better, faster, prettier, easier to fly, etc. than everyone else - I'm sure we will all appreciate the extra ideas and friendly competition:p

Also, are you in the NVRC or one of the other clubs in the NOVA area? Fly out at Poplar Ford field?
 

rockyboy

Skill Collector
Mentor
#31
That's how Steve Shumate did the elevators for his T-38:
https://www.rcgroups.com/forums/showthread.php?306817-T-38-Talon-Park-Jet

View attachment 92692

I made a DTFB version and used a BBQ skewer with a servo horn shoved over it. One could do better but it was what I knew how to do. I think Kevin Matusik uses a 3/16" dowel rod for that on his Raiden.
Over on the FW-42 team we've been thinking the same approach for this. If the physics in my head works the way I think it does, the pivot point should be such that there is an equal amount of surface area on both sides of the rod. This way the servo takes the smallest torsion force, and the bearings in the fuselage will take up the side loading forces.
 

HilldaFlyer

Well-known member
#32
I saw a jet Rafale last year, the canards where linked by a simple wooden rod on what I would call the "aerodynamic balance point" and only rotated by a simple servo, I think this would be rather easy to do. You just need to find out where to put the pivot point.
Sounds like a great idea. Do you know the mechanism of how the dowel was "attached" to the plane... like what kind of bearing was used to hold side-shift while still allowing rotation?
 

HilldaFlyer

Well-known member
#33
Foey! I was gonna do an XP-55! now I have to find something even more unusual! Best of luck to you, I can't wait to see your project grow.:D
Come join the fun... then there will be three of us building the XP-55. Certainly a lot of room in this for more. I bet all of us could do this same model and have a great time comparing notes.

Or, if you really want a challenge, try this one... I dare you:cool:

McDonnell XF-85 Goblin

 
Last edited:

HilldaFlyer

Well-known member
#34
Last edited:

HilldaFlyer

Well-known member
#35
Over on the FW-42 team we've been thinking the same approach for this. If the physics in my head works the way I think it does, the pivot point should be such that there is an equal amount of surface area on both sides of the rod. This way the servo takes the smallest torsion force, and the bearings in the fuselage will take up the side loading forces.
Your logic is sound and I tend to agree, however, from the drawings it appears the pivot point is more towards the front of the elevator. I wonder if this will make a difference.



Screen shot from one of the videos... the pivot is almost the leading edge.
 
Last edited:

HilldaFlyer

Well-known member
#36
All of these ideas are great. I have a real bad tendency to over-engineer structures like this. I was thinking ball bearings, steel rods, locking collars and clevis pins. Ok.. back to "model" building and not space shuttle engineering.
 
#37
Over on the FW-42 team we've been thinking the same approach for this. If the physics in my head works the way I think it does, the pivot point should be such that there is an equal amount of surface area on both sides of the rod. This way the servo takes the smallest torsion force, and the bearings in the fuselage will take up the side loading forces.
Actually, you'd want the pivot point closer to 1/4 chord of the stabilizer, where the aerodynamic center is located. One way to thing about this would be to think about just pulling of the stabilizer and balancing it as if you were balancing a flying wing. If you tried to balance it at 1/2 chord, it would pitch back violently (tailheavy). Same goes for the moment transfer to the servo with an aft pivot point.

You can actually use the wing CG calculator at 25% MAC to calculate where this should be for your geometry: http://fwcg.3dzone.dk/
 

HilldaFlyer

Well-known member
#38
Actually, you'd want the pivot point closer to 1/4 chord of the stabilizer, where the aerodynamic center is located. One way to thing about this would be to think about just pulling of the stabilizer and balancing it as if you were balancing a flying wing. If you tried to balance it at 1/2 chord, it would pitch back violently (tailheavy). Same goes for the moment transfer to the servo with an aft pivot point.

You can actually use the wing CG calculator at 25% MAC to calculate where this should be for your geometry: http://fwcg.3dzone.dk/
Thanks... good information. I was going to aim for 1/3 cord, kind of like CG. But now.. maybe I'll do it right.
 

rockyboy

Skill Collector
Mentor
#40
Actually, you'd want the pivot point closer to 1/4 chord of the stabilizer, where the aerodynamic center is located. One way to thing about this would be to think about just pulling of the stabilizer and balancing it as if you were balancing a flying wing. If you tried to balance it at 1/2 chord, it would pitch back violently (tailheavy). Same goes for the moment transfer to the servo with an aft pivot point.

You can actually use the wing CG calculator at 25% MAC to calculate where this should be for your geometry: http://fwcg.3dzone.dk/
Awesome! Thank you - this makes even more sense - prevents air flow spilling off the edges from causing control surface fluttering.

Whew - you just saved me at least two crashes trying to figure out what I was doing wrong! :black_eyed: