Following on my Carbon H-Quad, I have now built a foam one!! (Ok, it has a bit of carbon too)

The problem with the full carbon one was weight. Yes, it was super stiff but it was around 300g heavier than my X525 frame and thus my flight times were 3+ minutes shorter, thinner carbon plate would've helped but it's fairly expensive, difficult to come by (here) and difficult to work with.

My main priority was portability, it has to fold as small as possible and I also really do prefer flying the H-frames, orientation being the major advantage but also no props in onboard video.

I had a few blocks of a hard black EPP foam and I picked one up the other day and it was really firm (no twist) AND light (100g for the whole block), suddenly... bing!... I had spare arms for the X525 so why not.

A quick drawing in CAD to check the angles and sizes and some problem-solving with mountings and construction and here it is... took about 2 hrs to make and another 2-3 to assemble. I used the carbon pivot plates cut off from the old frame and they're just cyanoed to the foam with 2 bolts right through and 2 through just the arms and plates. Flies really well with very little twist (not enough to cause the yaw problems associated with twist)!

Weight is 925g ex-battery so 78g lighter than the X525 with the same components (The carbon frame was ~1300g).

Diagonal (open): Motor to motor (open): Length (folded, max): Width (folded, max): Weight:
EPP-HFQ 690mm 490mm 435mm 160mm 925g
X525 550mm 400mm 795mm 160mm



Before attaching the motors, closed Open, no components
3 4
5 In the old box!

Views: 14560

Comment by Murray Spoelstra on April 15, 2013 at 11:33pm

Nice one! Do you have pics with the camera mounted?

Comment by Graham Dyer on April 15, 2013 at 11:52pm

@ Murray, not yet, have changed the camera mount a bit but am trying to get rid of transmitted vibrations. Will post a pic soon though.

@ Glenn, this is a firm/hard type of EPP not the soft stuff that some of the new EPP planes are made from, it's quite a bit firmer than normal density polystyrene (EPS).

I've added a brace across the top which is probably unneccessary but has cut the small amount of flex in half, will post a pic of that too shortly

Comment by Graham Dyer on April 16, 2013 at 12:38am


Comment by Hugues on April 16, 2013 at 12:10pm

Hey, nice design! How did you practically (which tool or technique) empty the EPP block in such a nicely cut rectangle hole ?

Comment by Graham Dyer on April 16, 2013 at 12:14pm

:) thanks, just a very sharp snap-off blade utility knife and a metal straight edge ruler, it looks neater than it is.

Comment by Graham Dyer on April 16, 2013 at 12:25pm

Good question, it's definately quieter so am sure the EPP absorbs some of the vibration but I haven't measured or logged yet. Will do a test tomorrow, it certainly feels better in the hand, but the EPP is very firm so it's hard to say.

Comment by Rayrquest on April 26, 2013 at 5:22pm

Is there any way we can collaborate on your design?  I'm currently attempting to develop a UAV to carry a 4 pound payload. It would be fantastic to have your machine within it.  I have a long range flyer known as the Proteus developed by Scaled Composites at 1/8 scale.  The scope is to carry the payload in the plane, launch it in flight and have the quad perform more direct task other than recon. 

Comment by Graham Dyer on April 27, 2013 at 2:45am

Absolutely, it's a fairly simple design, only the carbon plates required a bit of precision cutting. I have some of the CAD drawings for both designs but they are incomplete, pretty amateurish and were really only done to get the proportions and dimensions right, you are very welcome to them though. Let me know if you want better or higher res photos too?


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