IVAN GOODCHILD wrote:B52 - an delicate subject in the LMA. There are a number of these currently being built in the States with various power trains. Having designed large EDF models, the latest being the Concorde, may I suggest you carry out some basic design calculations first. With a wing span of 16ft the model will have a wing area of over 20 sq ft, a design loading of say 32ozs/sq ft would give an AUW of around 40lbs. The power required to fly such a model with authority would be approx 5000 watts min. In order to obtain the eflux velocity from the fans I would suggest 1kW fans as min requirement. In order to obtain the fan speeds the battery voltage needs to be high at least 8S lipo drawing 40A. With 4 EDF on each wing there is also a need to balance the weight/power distribution and spar construction for assymetrical flight as the rudder on the B52 will not pick up a wing drop past approx 20degs. Taking all these factors into account the weight of the power train and its components will be in excess of 32lbs which means that the model AUW is likely to exceed the 20kg limit. I would therefore suggest that you contact Tony Hooper who looks after the over 20kg scheme and have a chat on the project which will answer most of your queries.
Ivan,
Thanks for chiming in, since you have mentioned that there are number of other large B52s that are being built in US presently, could you please link them on here. I would like to see how those guys are building there models. Presently my main concern is construction of the wings for this model, since fuselage is already built by another modeler rest is up to me to build it and fly it.
I also would like to know what type of spars are being used and are guys making foam wings or built up wings. I am also concerned about wing flex if that is needed on the model or not and if it's needed then how guys are achieving this critical aspect of there builds. I will be looking at EDF units and how many to use once i can get airframe weight established of this model other wise it's waste of time to look into them at this time.