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100 mph jwVampire

JamesWhom

Project Air on YouTube
#1
Hey everyone,

I'm in the process of going to the 'next level' with my foam board planes and have decided to try and smash the 100mph barrier.

Nerdnic has been quite an inspiration in doing this, especially as he has done it with some of his own designs.

Here is my set up -


NTM propdrive 3000kv 755w (what a beast!!)
TURNIGY Plush 60amp Speed Controller
TURNIGY 3000mAh 4S 40C Lipo Pack
5.5 x 4.3 E Turnigy Speed Propeller
Orange 6ch Receiver


The stuff installed in the partially completed airframe.

IMG_5672.JPG

IMG_5673.JPG

IMG_5674.JPG

So basically, I was hoping for some advice to help me do this. What do I need to reinforce (aside from the wing, done that already)? Any safety tips? Any piloting tips?

I thought that being able to brake the barrier with my own plane, the jwVampire, based on a deHaviland Vampire would be a great bit of promotion for me to release my plans for the design. It would be cool to say you can make one to go either 20mph with a small motor, but equally achieve 100mph with a beast of a power set up :)

Here is a video of someone's plane with the same motor:


I have some concerns with safety. The battery is positioned way up in the nose. If something goes wrong and this plane goes nose in, I have a feeling that there will be a sizeable explosion.

Anyway. Tell me your thoughts and advice!
 
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#2
Good luck with your project first of all, I cant see why you shouldn't be able to reach your goal,
I'm definitely too much of a novice to give any decent advice :(
Will you be altering you normal plans? I notice Nerdnics/Jayz speed wings are far more advanced than standard WINGS,
If possible wrap the battery in some dense foam? if that's a concern
Also how are you going to measure your speed?
May be unessesary but I'd want to reinforce the vertical and horizontal stabilizers but I like over engineering everything,
Metal gear servos?
And do it in stages 3s - 4s and altering props to suit so you get used to traveling at speed.
And make sure your cameras well taped down ...haha (sorry)
 
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jayz 84

Posted a thousand or more times
#3
Your vampire is a nice design. But she will need alot of work to stand up to 100mph. First thing you can do is lose some of the induced drag by closing up the undercamber wing tip and trailing edges. And build your wing with. A strong wood, carbon fiber or aluminum spar any will work. Next if you want it to last or avoid any mishaps Use metal gear servos. Next think about making your booms stronger just like your wing. Wood, carbon will do. Then just add a skewer to your horizontal stabilizer. To reduce any flex that you do not want. Ok now your power plant. Yes its very capable of pushing a plane to and past 100mph. But that will all depend on over all plane size, design and how much induced drag youll be fighting. As you can see in the video you posted the pusher jet is small and sleek making it a great design for speed. Not know how big your vampire design is i can only go by the pix and i can say i dont think it will be enough motor or prop to get you there, not saying it wont. But i think youll end up a little shy of the 100mph mark. You want your best chance at that mark with that motor. Shoot for a 80% build of your vampire with a 1800-2200 4s battery. Then i think youll be golden
 

JamesWhom

Project Air on YouTube
#4
Good luck with your project first of all, I cant see why you shouldn't be able to reach your goal,
I'm definitely too much of a novice to give any decent advice :(
Will you be altering you normal plans? I notice Nerdnics/Jayz speed wings are far more advanced than standard WINGS,
If possible wrap the battery in some dense foam? if that's a concern
Also how are you going to measure your speed?
May be unessesary but I'd want to reinforce the vertical and horizontal stabilizers but I like over engineering everything,
Metal gear servos?
And do it in stages 3s - 4s and altering props to suit so you get used to traveling at speed.
And make sure your cameras well taped down ...haha (sorry)
Thanks man, ah same here, but any advise is welcome!

I'm altering the plans in a few ways, but mostly only with the strength, so extra spars etc. I haven't used metal gear servos, but I may change them. On the Flite Test speed challenge video, I seem to remember they just used 9g servos.

I think your advice to take in stages is a really good idea. The only problem with that is the CG problems with using smaller batteries at first. I will be able to figure something out to solve that though!

Haha, yeah, I will try and make sure all cameras are properly secured. :)
 

JamesWhom

Project Air on YouTube
#5
Your vampire is a nice design. But she will need alot of work to stand up to 100mph. First thing you can do is lose some of the induced drag by closing up the undercamber wing tip and trailing edges. And build your wing with. A strong wood, carbon fiber or aluminum spar any will work. Next if you want it to last or avoid any mishaps Use metal gear servos. Next think about making your booms stronger just like your wing. Wood, carbon will do. Then just add a skewer to your horizontal stabilizer. To reduce any flex that you do not want. Ok now your power plant. Yes its very capable of pushing a plane to and past 100mph. But that will all depend on over all plane size, design and how much induced drag youll be fighting. As you can see in the video you posted the pusher jet is small and sleek making it a great design for speed. Not know how big your vampire design is i can only go by the pix and i can say i dont think it will be enough motor or prop to get you there, not saying it wont. But i think youll end up a little shy of the 100mph mark. You want your best chance at that mark with that motor. Shoot for a 80% build of your vampire with a 1800-2200 4s battery. Then i think youll be golden
Hey thanks for your advice. I'm a big fan of your work :)

Okay I will enclose the wing ends so there is no undercamber. I've already built the wings which have a nice wooden spar in them. Should be alright.

The size of the plane is pretty small. It has a 900mm wing span. Obviously it won't be as sleek as the plane in the video as you say, but the description on that video was doing well over 100 so hopefully it will be alright.

Thanks again.
 

nerdnic

nerdnic.com
Mentor
#6
I think your battery is a tad large. Your wing loading is gonna be very high and that motor will have a hard time getting up to speed on launch. You'll be fine once you're in the air but landing will be tricky. I have that same motor and it's more than capable of pushing 100 on the right set up.

Drop down to a 2200 and you'll be great. I really like the zippy compact 2200 40c 4s. For 20$ it's the best performing battery I've tested for the cost. This is the battery I use in my 800mm planes to push over 100. All the advice John gave is spot on also.
 

AkimboGlueGuns

Biplane Guy
Mentor
#7
Yup, I'll pretty much just be parroting John and Nic. Try to make something resembling an nn speedwing and I don't think you should have a problem breaking 100. Your booms will definitely need to be stronger, and you might want to use some 3/16" dowls or some bar-b-q skewers to strengthen the flat foam pieces like your stabilizers.

Good luck! I think with minimal modifications 100 mph is totally achievable.
 

JamesWhom

Project Air on YouTube
#8
I think your battery is a tad large. Your wing loading is gonna be very high and that motor will have a hard time getting up to speed on launch. You'll be fine once you're in the air but landing will be tricky. I have that same motor and it's more than capable of pushing 100 on the right set up.

Drop down to a 2200 and you'll be great. I really like the zippy compact 2200 40c 4s. For 20$ it's the best performing battery I've tested for the cost. This is the battery I use in my 800mm planes to push over 100. All the advice John gave is spot on also.
Thanks for the comment man. Yeah I get you. It does seem really heavy. I will go ahead and order a zippy compact 2200 40c 4s in the morning. Best to have as lower wing loading as possible as you say.

So grateful of you guys all being so willing to help out a noob in need haha. Thanks again.
 

JamesWhom

Project Air on YouTube
#9
Yup, I'll pretty much just be parroting John and Nic. Try to make something resembling an nn speedwing and I don't think you should have a problem breaking 100. Your booms will definitely need to be stronger, and you might want to use some 3/16" dowls or some bar-b-q skewers to strengthen the flat foam pieces like your stabilizers.

Good luck! I think with minimal modifications 100 mph is totally achievable.
Right, I will get myself some dowels and get the booms rock solid. I am in the process of gluing in some carbon spars to the tail surfaces, although I do think there will be still a degree of movement in them, meaning they still could catastrophically oscillate at a certain speed. I'll let you know how I get on. Cheers :)
 
#10
For your booms places like wickes sell 15mm x 15mm 2.4m or other sizes off 'light hardwood'
which is very light and strong, avoid pine its heavier, and there only £3 ish
 

JamesWhom

Project Air on YouTube
#12
Finished the prototype today.

Here it is with the first one:

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IMG_5741.jpg

IMG_5743.jpg

The improvements I have made, as advised, have been as follows

- Wooden spar in wing.
- Square wooden dowels in booms.
- Carbon spar in horizontal stabiliser.
- True airfoil on horizontal stabiliser.
- Airfoil smooth taper on trailing edge of wing. No 'step' on underside such as there is on an FT Spitfire etc.
- 'Filled in' undercambered wing tips with foam board.
- More streamlined canopy.
- Cut outs in intakes allow air to pass through whilst retaining strength and aesthetics.
 

Christopher14

Driftin' with the wind...
#15
I think the only problem you may have is the elevator. Too much throw and you're going to stall-spin on a snap-turn—although, the wing-chord is long enough that you may not have to worry about that, but I'm not sure, though. Your plane is a sight heavier then my racers (which come in at a wimpy 235-420g) so you may have to watch out for stall-spins anyway: short wing-chords and high wing-loadings don't play nicely! :black_eyed: lol.
Just be careful on the elevator when you turn near the ground. If you really want to figure out if it will stall-spin or not; take it up real high and try things out. I end up using high throws with like 80% expo on my racer's maiden flights.