How Strong Should a Model Plane's Spar Be to Survive Mid-Air Collisions?

AI Thread Summary
The discussion centers on building a model plane wing capable of surviving mid-air collisions, specifically using EPP foam and a carbon spar. The user seeks guidance on the necessary strength of the spar to withstand impacts from two planes traveling at 50 mph, equating this to a single plane hitting a solid object at 100 mph. It is noted that if both models are similar in size, the impact dynamics are comparable to a crash against a wall, but size discrepancies can alter the impact force experienced. The conversation emphasizes the importance of wing design, particularly for combat scenarios, to enhance durability during collisions. Understanding the impact force calculations is crucial for optimizing the spar's strength.
goony
Messages
5
Reaction score
0
Hi all I fly model planes in combat and need to build a wing that will withstand a head on impact! I am going to use epp foam to form the wing and a carbon spar
the foam will be cut at the spar line and the spar will be a H rotated 90deg so that the foam slots in either side
what I need to know is how strong do I need to make the spar

so its 2 objects both traveling at 50 mph impacting on a surface area of 1 inch
I assume that's the same as 1 object impacting an imovable object of 1 inch at 100 mph
but that's all I know as I am a rather thick so if you could tell me the answer and also explain the calculation Id really appreciate it

kind regards goony
 
Engineering news on Phys.org
please ignore the absortion of the epp foam i just need to know what the impact force would be

regards goony
 
The closer the model is to a "combat" wing, the better the chance of survival. The "classics" are getting harder to find:

http://www.zagi.com
http://www.fatlion.com/sailplanes/boomerang.html

The newer ones are still around:

http://www.combatwings.com/catalog/product_info.php?cPath=22&products_id=32&product_name=Ready%20to%20Fly%20XL%20Slope%20Glider

Link to videos (plenty of these at other web sites as well):

http://www.combatwings.com/catalog/video_electric.php

Also note that if the two models are virtually identical then a 50mph head on isn't much different than a 50mph crash into a solid wall. If one of the models is much larger, then the smaller model starts experiencing the effects approaching a 100mph crash into a solid wall.
 
Last edited by a moderator:
Hi these arnt gliders they are powerd by 30cubic inch methanol engines and we attatch a 30ft streamer to them the idea is to cut the other streamers but midair impacts are quite common and we use a straight leading edge to snag streamers if they were swept back the streamer would slide off
the wing will be 6ft span and made from EPP foam the opposition are 4ft and made from correx

goony
 
Hi all, I have a question. So from the derivation of the Isentropic process relationship PV^gamma = constant, there is a step dW = PdV, which can only be said for quasi-equilibrium (or reversible) processes. As such I believe PV^gamma = constant (and the family of equations) should not be applicable to just adiabatic processes? Ie, it should be applicable only for adiabatic + reversible = isentropic processes? However, I've seen couple of online notes/books, and...
I have an engine that uses a dry sump oiling system. The oil collection pan has three AN fittings to use for scavenging. Two of the fittings are approximately on the same level, the third is about 1/2 to 3/4 inch higher than the other two. The system ran for years with no problem using a three stage pump (one pressure and two scavenge stages). The two scavenge stages were connected at times to any two of the three AN fittings on the tank. Recently I tried an upgrade to a four stage pump...

Similar threads

Back
Top